Communications – Muhammad Nazmul Islam, Sundar Subramanian, Junyi Li, Navid Abedini, Bilal Sadiq, Qualcomm Inc
Abstract for “Rach conveyance DL synchronization beam info for different DL-UL correspondence states
These are methods, systems, devices, and protocols for wireless communication. An UE may receive a downlink signal (DL) from a base station using one or more DL beams. The UE can identify a selected DL beacon of one or more DL be(s) to allow communications between the base station and the UE. A scheduling request message may be transmitted by the UE to the base station using either a resource or a waveform that is selected based at most in part on the selected DL beacon.
Background for “Rach conveyance DL synchronization beam info for different DL-UL correspondence states
“The following applies generally to wireless communication and, more specifically, to random access channel (RACH), conveyance of downlink information (DL) for various downlink?uplink (DL?UL) correspondence states.
Wireless communications systems are used to transmit various communication types, including voice, video, packet data and messaging. These systems can support communication with multiple users by sharing system resources (e.g. time, frequency and power). Multiple-access systems can include code division multiple acces (CDMA), time division multiple accessibility (TDMA), frequency division multipleaccess (FDMA), and orthogonal frequency division multiple access systems (OFDMA), such as a Long Term Evolution system (LTE). Wireless multiple-access communication systems may have a number base stations that support communication with multiple communication devices. These communication devices may also be known as user equipment (UE).
Wireless communication systems can operate at millimeter-wave (mmW), frequency ranges (e.g. 28 GHz, 40 GHz, 60 GHz, etc.). These frequencies can cause increased signal attenuation (e.g. path loss) which could be affected by temperature, barometric pressure and diffraction. Signal processing techniques such as beamforming can be used to combine energy coherently and overcome path losses at these frequencies. Transmissions from the UE and base station may be beamformed due to increased path loss in mmW communications systems.
Wireless communications between two wireless nodes (e.g. between a base station, UE) may use beams, or beam-formed signals to transmit and/or receive. A base station can transmit beamformed synchronization signal on downlink (DL), synchronization beams. A synchronization signal may be received by a UE on one or more DL synchronization beams. This will allow the UE to initiate a RACH procedure. Sometimes, the UE might send a message to base station as part the RACH procedure. The base station may assume the uplink beam (UL) on which the RACH message was received is representative for a DL beam that should be used by the base station in communicating with the UE. The base station assumes that DL-UL correspondence is being exchanged. For various reasons, however, the correspondence between DL channel channel and UL channel could be missing. The base station assumption could be wrong, and the DL beam chosen by it may not be the best beam to communicate with the UE.
“The techniques described herein relate to improved methods and systems, devices, and apparatuses that support RACH conveyance DL beam information for different DL-UL correspondence states. The described techniques allow a base station transmit DL signals to an UE. The DL signals can be transmitted via DL beam(s). The UE can use the DL beam of the DL beams that can be used to communicate with the base station (e.g., DL communication). For transmission of a RACH message (e.g. RACH msg1), the UE can select a resource or random access channel (RACH), waveform. The UE may choose the RACH or resource waveform based upon the DL beam. The UE can transmit to the base station the RACH message on the selected resource or the RACH waveform. The RACH message may be received by the base station on the resource or the RACHwaveform. It will identify the DL beam that the UE selected based on the resource or the RACHwaveform. For subsequent communications with UE, the base station can use the selected DL beam.
“A method for wireless communication” is described. This could include receiving a DL message from a base station on one, or more DL beacons, identifying a selected DL beam of the one or many DL beams for communications between the UE and the base station, and sending a RACH message/scheduling message/beam tracking message to the base stations using at least one resource or a waveform chosen based at most in part on the selected DLbeam.
“A wireless communication apparatus is described. The apparatus can include means to receive a DL signal on a base station’s one or more DL beacons, means to identify a selected DL beam of the one/more DL beams for communications between the base station and the UE, and means to transmit a RACH message/scheduling message/beam tracking message to the base stations using at least one resource or a waveform chosen based at most in part on the selected DL-beam.
“Another apparatus is described for wireless communication. The apparatus can include a processor and memory for electronic communication with it. Instructions may be stored in the memory. Instructions may be used to instruct the processor to send a DL signal to a base station on one, more or all DL beams. The processor will then identify a selected DL beacon of the one or many DL beams to transmit a RACH message/scheduling message/beam tracking message to the UE using at least one resource or a waveform chosen based at most in part on the selected DL-beam.
A non-transitory computer-readable medium for wireless communication has been described. Instructions may be included that allow a processor to detect a DL signal coming from a base station, to identify a selected DL beacon of the one or multiple DL signals for communications between the UE and the base station, and to transmit a RACH message/scheduling message/beam tracking message to the base stations using at least one of a resource, or a waveform chosen based at most in part on the selected DL-beam.
“In some cases of the non-transitory computer readable medium, apparatus and method described above, the waveform includes one of a scheduling request, or a RACHwaveform.”
“In some cases of the non-transitory computer readable medium, apparatus and method described above, the digital signal DL comprises either a synchronization signal, or a reference signal.”
“In some cases of the non-transitory computer readable medium, apparatus and method described above, the selected resource/waveform includes: Selecting the resource or waveform based at most in part on the index of the selected DLB beam. The selected resource or waveform is described in some of the above-described methods, apparatuses, and non-transitory computers-readable media.
“In some cases of the method, apparatus and non-transitory computers-readable medium described above transmitting the RACH/scheduling message/beam recover or beam tracking messages comprises: transmitting RACH/scheduling message/beam recuperation or beam tracking message for the entire duration of a corresponding random acces subframe. The following examples illustrate the non-transitory computerreadable medium, apparatus and method. The process of identifying the preferred DL beacon is performed.
“In some cases of the non-transitory computer readable medium, apparatus and method described above, identifying a selected DL beam involves: Identifying the DL beacon based at minimum in part on the DL signal from one or more DL beams that meet a transmit power condition. The non-transitory computer readable medium, apparatus and method described above may also include methods, features, or instructions to select the resource/RACH waveform for transmission/scheduling request/beam recovery/beam tracking message to base station. The selected DL beam is used as the basis for the RACH waveform or resource being selected.
“Some examples of the non-transitory computer readable medium, apparatus and method described above include selecting the RACH waveform by selecting a RACH preamble or a cyclic shifting, or any combination thereof, determined at least partially on the index of the selected beam. One or more DL transmit beams may not be received at the base station from one or more UL receiver beams. This could occur in some instances of the apparatus, method, and non-transitory information-readable medium. It is possible that the absent correspondence could be due to the one or two DL transmit beams with different beam directions than one or more UL receiver beams.
“Some examples of the non-transitory computer readable medium, apparatus and method described above may also include features, means or instructions for identifying correspondence that is absent by receiving information at the base station in a master or system information block.
“Some examples of the non-transitory computer readable medium and method described above may also include processes, features and means or instructions for selecting the resource. These can be based at minimum in part on identification of the missing correspondence and transmitting the RACH message/scheduling message/beam recuperation or beam tracking message (for the entire duration of a RACH Subframe) based at most in part on the absence of the correspondence. The method, apparatus and non-transitory computer readable medium may also include instructions, features, or means for selecting the resource/RACH waveform, at least partially based on the absence of correspondence.
“Some of the non-transitory computer readable media, apparatus and method described above may also include features, means or instructions for receiving the absence of correspondence in a master or system information block. The non-transitory computer readable medium and apparatus described above could also include instructions, processes, features, or means for transmitting a signal that there is no correspondence between one or more DL beams coming from the base station or one or two UL beams coming from the UE. The non-transitory computer readable medium and the method described may also include the following: processes, features and instructions to transmit the RACH message/scheduling message/beam rescue or beam tracking message from the base station during the first symbol of a first random acces subframe and the second symbol of another random access subframe. The non-transitory computer readable medium and the method described above could also include the following: processes, features, methods, or instructions to transmit the absence of correspondence in a RACH 3 message, a physical control channel (PUCCH), a physical shared channel (PUSCH), or a PUCH).
“Some of the non-transitory computer readable media, apparatus and method described above may also include features, means or instructions for receiving information about a nature or correspondence between one or more DL beams at the base station and one, or more UL beams at the UE. The nature of correspondence can correspond to any of the following: partial correspondence, full correspondence or none.
“Some examples of the non-transitory computer readable medium and method described above may also include features, means or instructions for determining whether correspondence is present. This can be done based upon the nature of the correspondence and selecting a transmission date for sending the RACH message/scheduling message/beam recuperation or beam tracking message to base station. The transmission time may include a symbol for a corresponding random-access subframe. The apparatus, method, and non-transitory computer readable medium described may also include features, means, or procedures for determining if there is partial correspondence. These can be based on an indication of the nature and choosing a transmission time to transmit the RACH message/scheduling message/beam recuperation or beam tracking message. Some examples include multiple symbols from a corresponding random-access subframe as part of the transmission time.
“Some of the non-transitory computer readable media described above may also include features, means or instructions for selecting a transmission frequency range and a transmission time. The non-transitory computer readable medium and apparatus described above may also include instructions, features, or means for selecting the resource. These can be based at minimum in part on the symbol associated with the DLS signal, as well as the indication of the nature and content of correspondence. The non-transitory computer readable medium, as well as the apparatus, may also include the following: processes, features and means or instructions for receiving the information about the nature of correspondence via a physical broadcast channel (PBCH), or an extended (ePBCH). The method, apparatus and non-transitory computers-readable medium may also include instructions, features, means or processes for receiving the information about the nature of correspondence in a MIB, a SIB, or other types.
“In some cases of the method, apparatus and non-transitory computers-readable medium described above the selected DL beam may differ from a selected UL beacon from the UE. The one or more DL beacons from the base station may not be contained within the same symbol of a synchroization subframe. In these cases, selecting the resource for the transmission of the scheduling request messages involves selecting the waveform or resource based at most in part on the symbol associated with the selected DL beam.
“In some cases of the non-transitory computer readable medium and method described above, the resource could be associated with one or several tones in a component carriers. The resource can be associated with a component carrier in some of the above-described methods, apparatuses, and non-transitory computers-readable media. The non-transitory computer readable medium, apparatus and method described above could also include features, means or instructions to select a combination of the resource or the RACH waveform in order to transmit the RACH message/scheduling message/beam recuperation or beam tracking message to base station.
“A method for wireless communication” is described. This may involve transmitting a DL message on one or several DL beacons, receiving from a UE a RACH message/scheduling message/beam recover or beam tracking message.
“A wireless communication apparatus is described. The apparatus can include means to transmit a DL signal using one or multiple DL beams, as well as means to receive, on at most one of a resource/beam recovery message/beam tracking message, a RACH message/scheduling message/beam tracking message from a UE.
“Another apparatus is described for wireless communication. The apparatus can include a processor and memory for electronic communication with it. Instructions stored in the memory may also be included. Instructions may be used to instruct the processor to transmit a DL message on one or several DL beams, to receive on at least one of a resource/beam recovery message/beam tracking message from a UE and to identify, based at minimum in part on the resource/waveform, a selected DL beacon of the one/more DL beams for communications between the base station and the UE. The selected DL beam can then be used to transmit one or multiple subsequent messages to the UE
“A non-transitory computer-readable medium for wireless communication” is described. Instructions may be included that allow a processor to transmit a DL message on one or several DL beams, to receive on least one of a resource/beam recovery message or beam tracking message from a UE and to identify, based at minimum in part on the resource/the waveform, a selected DL beacon of the one/more DL beams for communications between the base station and the UE. The selected DL beam can then be used to transmit one or multiple subsequent messages to the UE
“In some cases of the non-transitory computer readable medium and the method described above, identifying a selected DL signal consists of associating the waveform or resource with an index of that selected DL beam. In some cases, the apparatus and non-transitory computer readable medium are described as: Associating the resource/waveform with a symbol from a subframe in the DL signal.
“In some cases of the method, apparatus and non-transitory computers-readable medium described above receiving the message/scheduling message/beam recover or beam tracking messages comprises: receiving the message/scheduling message/beam recuperation or beam tracking message for the entire duration of the corresponding random access frame. Some examples of the method, apparatus and non-transitory computers-readable medium mentioned above include: Receiving the RACH/scheduling message/beam recover or beam tracking messages on a plurality UL beams.
“Some examples of the non-transitory computer readable medium and method described above may also include processes, features or means or instructions for measuring a quality RACH message/scheduling message/beam recovery message or beam tracking message received on a plurality of UL beams. The method, apparatus and non-transitory computers-readable medium may also include features, means or instructions to determine a specific UL beam for communications between the UE and the base station based at most in part on its quality.
“Some examples of the non-transitory computer readable medium and method described above include: measuring one or more reference signals received power (RSRP), received signal strength indicator(RSSI), reference signal received quality [RSRQ]), signal to noise ratios (SNR) or signal to interference plus noisy ratio (SINR). The method, apparatus and non-transitory computer readable medium described above include the following: Identification of the selected DLB beam is done based at minimum in part on the resource/waveform of the RACH/scheduling request/beam recovery/beam tracking message.
“In some cases of the non-transitory computer readable medium, apparatus and method described above, identifying a selected DL beacon consists of: identifying the selected DL bead based at minimum in part on a RACH Preamble of RACH message, a cyclic shifting of RACH message or combinations thereof. The method, apparatus and non-transitory computers-readable medium described in some cases lacks correspondence between one or several DL beams from base station and one (or more) uplink beams at base station. In these cases, the absent correspondence is associated to the one, two, or more of the DL beams with different beam directions than one or multiple UL beams.
“Some of the non-transitory computer readable media, apparatus and method described above may also include features, means or instructions to identify that correspondence is absent between one or more DL beams at the base stations and one or two uplink (UL), beams at the station.”
“Some of the non-transitory computer-readable media described above may also include features, means or instructions for receiving an indicator that there is no correspondence between the one or two DL beams at the base station and one, or more UL beacons from UE and mapping DL bes used in transmitting channel state information (CSIRSs) to UL beams to transmit sounding references signals (SRSs) or mapping ULbes used by to transmit sounding refer signals (SRSs) to DL-channel state information (CSI-RSs to transmitting channel state information (CSI-reference signals) to DL beams to send channel state information (CSI-res to CSI-s to a channel state information (CSI-line information to CSI-s to DL beams to DL beams to s to DL to CSI-state information to s to s to s to s to s to s to s to s to s to s to DL beams to DLs to s to s to s to s to s to s to s to s to s The non-transitory computer-readable media described above could also include the following: processes, features and instructions to receive an indication that there is no correspondence between the one or two DL beams at the base station and one of the UL beams at the UE, mapping UL beacons used to transmit sounding reference signals (SRSs) to DL beams which are used to transmit channel state information reference signals (CSI-RSs), or mapping UL beams to UL beams to DL beamed in UL training, or mapping UL beams to UL beams to UL beams to UL beams to UL beams to UL beams to UL beams UL beams to UL beams to UL beams to UL beams to UL beams to UL beams in UL beams to DL beams to UL beams to DL beams to UL beams to UL beams to UL beams to UL beams to UL beams to DL beams to UL beams to UL beams to UL beams to DL beams to UL beams to DL beams to UL beams to UL beams UL beams to DL beams to DL beams to DL beams to DL beams to DL beams to DL beams to UL beams to DL to DL to DL to DL to DL to DL to DL to DL to DL to DL to s used in DL to DL to DL to DL to DL to DL to DL to DL to DL to DLs used in DL to DL to DL to DL to DL to DL to DL to DL to DLs used in to DL to DL to DL to DL to DL to DL beams to DL to DL to DL to DL to DL beams to DL to DL to DL to DL beams to DL to DL to DL to DL to DL to DL to DL to DL to DL beams to DL to DL to DL be to DL to DL to DL to DL to
“In some cases of the apparatus, method, and non-transitory computer readable medium described above, the selected DL beacon from the base station might be different than a selected UL beam coming from the UE. The resource could be associated with one or several tones in a component carrier, depending on the example of the apparatus and non-transitory information-readable medium. The resource could be associated with a component carrier in some of the above-described examples of the apparatus, method, and non-transitory computing medium.
The carrier frequency may cause a greater loss of free space. Transmission in millimeter-wave (mmW) systems could also be affected by non-line of sight losses (e.g., penetration loss and oxygen absorption loss, leaf loss, and so on). These high path losses may be overcome by the base station and user equipment (UE) during initial access to detect or discover each other. The present disclosure provides improved access to mmW systems.
“Aspects disclosed are first described in the context a wireless communication system. The described techniques allow a UE (user equipment) to indicate to a base station a selected downlink beam (DL), by selecting a corresponding resource (RACH waveform) for transmission of a RACH/scheduling request/beam recovery/beam tracking message. The base station might transmit DL signal(s), on DL beam(s). The UE might select a DL beam that can be used to transmit DL signals (e.g. from the base station to UE). The UE can select a resource or a waveform (e.g. a RACH waveform, a scheduling request waveform, or a RACH message) to transmit the RACH message/scheduling message/beam recovery or beam tracking message from the base station. Selection is based upon the selected DL beam. The UE can then transmit the RACH message/scheduling message/beam recover or beam tracking message using the selected resource/or RACHwaveform to the base station. The base station then receives the RACH message/scheduling message/beam recover or beam tracking message using the selected resource/or RACHwaveform. It uses the resource/or RACHwaveform to identify the selected beam. The UE can select a resource (e.g. channel) that corresponds with the timing feature of the DL signals (e.g. symbol). The selected DL beam may be used by the base station for communications between the base station and the UE (e.g. for future DL communications). A resource can be a time resource or a frequency resource in some cases.
“Aspects are further illustrated and described by reference to apparatus diagrams and system diagrams and flowcharts that pertain to RACH conveyance DL synchronization beam info for different DL-UL correspondence states. In some cases, correspondence could refer to reciprocity.
“FIG. “FIG. 1 illustrates a wireless communication system 100 according to various aspects of this disclosure. Wireless communications system 100 comprises base stations 105 and UEs 115 as well as a core network 130. The wireless communications system 100 could be either an LTE (or LTE Advanced) network in some cases.
“Base stations 105 can wirelessly communicate with UEs 115 using one or more base station antennas. Each base station 105 can provide coverage in a specific geographic area 110. The wireless communications system 100 shows communication links 125. These may include UL transmissions between a UE 115 and a base stations 105 or DL transmissions between a UE 115 and a UE 115. UEs 115 can be distributed throughout wireless communications system 100. Each UE 115 could be mobile or stationary. A UE 115 can also be called a mobile station or subscriber station. Each UE 115 could be stationary or mobile. A UE 115 could also refer to a cellular phone or a personal digital assistant (PDA), a wireless device, a wireless communication device and a handheld computer, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a client, a client, or some other suitable terminology.
“Base stations may communicate with each other and the core network 130. Base stations 105, for example, may communicate with the core network 130 via backhaul links 132, (e.g. S1, etc.). Base stations 105 can communicate over backhaul link 134 (e.g. X2, etc.). Either directly or indirectly (e.g. through core network 130). Base stations 105 can perform radio configuration and scheduling to communicate with UEs 115. They may also operate under the control a base station controller (not illustrated). Base stations 105 can be macro cells, small cell, hot spots or other types depending on the situation. Base stations 105 can also be called eNodeBs (eNBs 105).
“During an initial access procedure (also referred to as a RACH procedure), UE 115 can transmit a RACH preamble from a base station 105. This could be called RACH message 1. The RACH preamble could be randomly chosen from 64 predetermined sequences. This could allow the base station 105 distinguish between multiple UEs 115 trying access the system simultaneously. The base station 105 might respond by sending a random access request (RAR), also known as RACH message 2, which provides an UL resource grant and a timing advance. It may also provide a temporary mobile radio network temporary identification (C-RNTI). If the UE 115 is previously connected to the same wireless network, the UE 115 could transmit a radio resource control (RRC), connection request or RACH message 3. Radio resource control (RRC), connection requests may indicate why the UE 115 connects to the network (e.g. emergency, signaling or data exchange). The base station 105 might respond to the connection request by sending a RACH message 4 to the UE 115. This message may contain a contention resolution message or RACH message 4. It may also provide a new CRNTI. The UE 115 can proceed with RRC setup if the UE 115 is able to receive a contention resolution message that contains the correct identification. The UE 115 can continue with RRC setup if it does not receive a contention message (e.g. if there is a problem with another UE 115).
“Wireless communication network 100 may operate in an ultrahigh frequency (UHF), frequency region that uses frequency bands ranging from 700 MHz up to 2600MHz (2.6GHz), though in some cases WLAN networks can use frequencies as high at 4GHz. The decimeter band may also be called this region, as its wavelengths are approximately one to one meter long. UHF waves can propagate mostly by line-of-sight, but may be blocked by buildings or other environmental features. The waves can penetrate walls enough to provide service to UEs 115 indoors. Transmission of UHF waves has a shorter range and smaller antennas than transmission using the higher frequencies (and longer waves), portion of the spectrum. Wireless communication system 100 can also use extremely high frequency (EHF), portions of the spectrum in certain cases (e.g. 30 GHz to 300GHz). This area may also be called the millimeter spectrum, as it has wavelengths that range from one millimeter up to one centimeter long. EHF antennas can be smaller and less spaced than UHF antennas. This may allow for the use of an antenna array within a UE 115 in certain cases (e.g. for directional beamforming). EHF transmissions can be subject to greater atmospheric attenuation, and may have a shorter range than UHF transmissions.
“Specifically, wireless communication system 100 can operate in mmW frequency bands (e.g. 28 GHz, 40 GHz, 60 GHz etc.). These frequencies can cause increased signal attenuation (e.g. path loss) which can be affected by temperature, barometric pressure and diffraction. Signal processing techniques, such as beamforming, can be used to combine signal energy coherently and eliminate path loss in certain beam directions. A device such as a UE 115 may choose a beam direction to communicate with a network. This is done by choosing the strongest beam among a variety of signals transmitted from a base station 105. One example is that the signals could be DL synchronization signal (e.g. primary or secondary synchronizations signals) or DL references signals (e.g. channel state information reference signs (CSI-RS),) transmitted from base station 105 during discovery. For example, the discovery procedure can be cell-specific and directed in incremental directions within the coverage area 110 at the base station 105. In certain cases, the discovery procedure can be used to identify and select beams to be used in beamformed transmissions between a UE 115 and base station 105.
“Base station antennas can sometimes be found within an antenna array. An antenna tower, or one or more base station antennas, may have multiple antenna arrays. Antennas and antenna arrays that are associated with base station 105 can be found in different geographic locations. An antenna array or multiple antennas may be used by a base station 105 to perform beamforming operations in order to transmit directional information with a UE 115.
“Wireless communication 100 could include or be multicarrier mmW wireless communications system. A number of aspects of wireless communication systems 100 could include a UE 115 or a base station 105 that can be configured to support RACH conveyances of DL synchronization beam data for different DL-UL correspondence states. The base station 105 might transmit DL signal(s), on DL beam(s). The UE 115 could select a DL beam that can be used to transmit DL signals (e.g. from base station 105 to UE 115). The UE 115 can select a resource or a RACH waveform to transmit the RACH message from the base station 105. Selections are based on the selected DL beacon. The UE 115 can then transmit the RACH message from the base station 105 by using the selected resource or RACH waveform. The base station 105 then receives the RACH message using the selected resource or RACH waveform. It uses the resource and/or the RACH waveforms to identify the selected DL beacon. The UE 115 can select a resource (e.g. channel) that corresponds with the timing feature of the DL synchronization signals (e.g. symbol). The selected DL beam may be used by the base station 105 for communications between the UE 115 and the base station 105 (e.g. for future DL communications).
“FIG. 2. This is an example of a process flow 200 to transmit DL synchronization beam data for different DL-UL correspondence states. Process flow 200 could implement aspects of wireless communications system 100 as shown in FIG. 1. Process flow 200 could include a UE 115a and a basestation 105a. These may be examples of the corresponding devices in FIG. 1. Base station 105a could be a mmW station or a serving station for UE 115a.”
“At 205 base station 105-a might transmit information about correspondence related to DL beams at base station side. In certain aspects, base station 105 may indicate correspondence with UE 115.a. One example is that a bit could be used to transmit the correspondence indication. Base station 105-a could implicitly indicate correspondence in other aspects. UE 115 may be able to deduce whether correspondence exists at base station 105a by mapping DL beams to RACH resources. One example is that if the RACH resources and the DL beams are configured using TDD, then this could indicate that base station 105a might have correspondence.
“Base station 105-a might include the indications of correspondence in a master data block (MIB), or a system information blocks (SIB), transmitted to UE 115.a. The base station might transmit the MIB via a physical broadcast channel (PBCH) and the SIB may be transmitted over an extended PBCH. The indication could be based on a preamble. One preamble may indicate no correspondence. A second preamble may indicate partial correspondence. A third preamble may indicate full correspondence. UE 115a can determine whether there is complete correspondence, partial correspondence or none. If UE 115a finds that there is no correspondence, UE 115a can select a UL beam to communicate with base station 105 -a that is different than the DL beam used at base station 105 -a.
“Also, or alternatively, UE 115a at 205 may transmit information about correspondence associated with UL beams on the UE side. UE 115 may, for example, transmit a nature and type of correspondence between one or two receive DL synchronization beacons at UE and one (or more) transmit uplink beams (UL) at UE. This could include the indication of correspondence via RACH messages (e.g. RACH msg 1, RACH msg 3, or over a physical control channel (PUCCH), or a physical downlink shared channel (PUSCH). Base station 105 may be able to receive correspondence from the UE side. Based on this indication, base station 105 may map beams used for transmitting channel state information reference signal (CSI-RSs), to beams used for transmitting sounding reference signal (SRSs) or vice-versa. Base station 105-a can also determine to map beams used for DL beam training to beams utilized in UL beam training, or vice versa, based on the indication.
“At 210 base station 105 may transmit (and receive UE 115-0) a DL sync signal to UE115-a. The DL synchronization signals may be a beamformed signal that is transmitted from base station 105a using DL synchronization beam(s). The DL synchronization signals may be associated with an indicator and/or a symbol for a subframe. A transmit power condition may also be associated with the DL synchronization signals.
“Base station 105a transmits a number of DL synchronization signal during a synchronization frame in some aspects. Each DL synchronization signals may be transmitted using a symbol in the synchronization subframe. For example, DL synchronization sign 1 may be transmitted using symbol 1, while Dl synchronization symbol 2 may be transmitted using symbol 2, etc
“At 215, UE 115 -a may identify a select DL beam from the DL synchronization beams for use in communications between base station 105 -a and UE 115 -a. UE 115 may identify the preferred DL beam by identifying a signal strength or quality of the DL synchronization signals (e.g. high received signal strength, low interference level). UE 115a may, in certain aspects, identify the selected DL beam using a transmit strength condition of the DL synchronization signals on the DL synchronization beams (e.g., a transmit force above a threshold).
“At 220, the UE 115 a may select a resource or RACH waveform to transmit the RACH message from base station 105 -a. The selected DL signal may determine the resource or RACH waveform. The RACH and/or resource waveforms may be associated with component carriers and/or with component carriers.
“At 225, UE 115 -a can transmit a RACH message from base station 105 -a. The RACH message can be transmitted using the RACH resource selected and/or RACH waveform. The RACH message can be transmitted for the entire duration of a random access subframe. For example, it may be transmitted at each symbol in the random access subsection. The RACH message can be transmitted for the entire duration of the corresponding random access slot, subframe or occasion. These terms can be used to describe a time period during which the gNB sweeps a portion or all of its receive beams in order to receive RACH messages. In certain aspects, UE 115 a may choose a RACH waveform to transmit the RACH message. Based on the selected beam, the RACH waveform can be chosen. It may include a RACH preamble or a cyclic shifting, among other things. In certain aspects, UE 115a may transmit the RACH message using a number of UL beams.
“At 230 base station 105a may identify the selected beam. Base station 105 may be able to identify the selected beam DL beam using the RACH waveform and/or resource used in the RACH message transmission. Base station 105 may, in certain aspects, identify the selected DLB beam by associating RACH waveform and resource with an index of the selected beam. Base station 105-a can identify the selected DL beacon in certain aspects by associating RACH waveform and resource with a symbol of a subframe for the DL synchronization signals of the selected DL beam.
Base station 105-a might identify the selected DL beam based upon the RACH waveform in the RACH message. Base station 105-a, for example, may identify the selected beam based on RACH preamble, the RACH message’s cyclic shift, and other factors.
“At 235 base station 105 -a may transmit additional messages to UE 115 -a using the selected DL beacon. The selected DL beam may be preferred in some cases. Base station 105 may also use the RACH message from UE 115 to determine a selected UL beacon for communications between UE 115 and base station 105. Base station 105-a might measure the quality of the RACH message received on a plurality UL beams, and then determine the selected UL beacon based on that measurement. The quality of RACH messages can be measured by measuring the reference signal received power (RSRP), the received signal strength indicator(RSSI), and the reference signal received quality quality (RSRQ).
“UE 115-a can measure the RSRP of a received message transmitted on a synchronization block (e.g. where a combination or more synchronization signals is transmitted in a particular direction) to determine the best signal. UE 115 -a may not be able to identify the strongest port associated to a symbol. UE 115 -a may indicate or transmit a preferred DL beam to basestation 105-a using other spreading codes (e.g. orthogonal cover code (OCCs). Base station 105a may transmit additional reference signals, such as a beam signal (BRS), mobility signal (MRS), and others. Inside symbols used to synchronize signals 205 and UE 115 may identify the best transmission port (e.g. best downlink transmission beam ID). UE 115a could therefore return the best downlink transmission beam identification by using different spreading codes.
Base station 105 may not have beam correspondence. Base station 105 can request UE 115 to transmit RACH in all symbols within the RACH slot. Base station 105 may then determine the best uplink reception beam by analyzing the quality of the received RACH signals. Base station 105 may establish an association between a transmit/receive beam channel or downlink signal and a subset RACH resources. This association may then be used to determine the downlink transmission beam, such as for sending Msg. UE 115 may choose the RACH resource subset or the RACH preamble indices subset based on downlink measurements of received signals. A preamble index can include a preamble sequence and an OCC index in these cases. OCC support is also possible. OCC indices can be used to indicate a subset or preambles in some cases.
“In certain aspects, there may not be correspondence between the DL synchronization beams at base station 105a and UL beams at UE 115a. In some cases, the selected DL beam might differ from the selected UL beam. Some aspects of the disclosure could allow partial or complete beam correspondence between the DL transmit beams and UL receive beams. Partial correspondence may allow the RACH message to be transmitted at 225 over a transmission time that has a center symbol that corresponds to either the symbol associated to the best DL synchronization beacon or the best received signal strength. Similar to the above, UE115-a can determine the RACH preamble for the RACH message transmitted at 225 using the best Dsynchronization beam. UE115-a could determine the subcarrier area used for transmission of RACH message at 215 based upon the best DL sync beam. This could be applicable to frequency division duplexing systems (FDD), where partial beam correspondence may not exist between the DL/UL. There may be a variation in the amount of partial beam correspondence from one situation to another. Some examples may show absent correspondence as a result of different channel propagation characteristics (e.g. different transmit power levels, different angles of departure and/or arrival etc
“In certain cases, correspondence might be present at base station 105a. The base station 105 may transmit different DL synchronization signal at different times and the base stations 105-a and UE 115 may simultaneously receive the RACH resources through a digital receiver subsystem. This may avoid analog beam constraints. A base station 105 may ask that the UE 115a map DL synchronization signal to RACH resources or waveforms. A RACH detector may be used to analyze each receive beam path at the base station 105.
The beam correspondence between the DL transmit beams and UL receive beams may be supported by aspects of the disclosure. If correspondence exists, the RACH message transmitted to 225 could be transmitted at a transmission time that corresponds with the best DL synchronization beacon or the symbol corresponding the best DL synchronization beacon.
“FIG. 3. This is an illustration of a system 300 that supports wireless communications and supports RACH conveyance information for various DL -UL correspondence states. System 300 could be one example of the wireless communication system 100 described in FIG. 1. System 300 could be a wireless communication system that uses mmW. System 300 could include a UE 115b and a basestation 105-b. These devices may be similar to the ones in FIGS. 1. and 2. System 300 is a general illustration of a discovery procedure in which UE 115b discovers base station 105b based upon DL synchronization signals transmitted via DL synchronization beams.
“Base station 105-b could be a mmW station that transmits beamformed transmissions to UE 115b. Base stations 105-b can transmit beamformed transmissions or directional transmissions directed towards UE 115.
“For instance, base station 105b may transmit DL synchronization signals on DL synchronization beams 305. Base station 105b may transmit DL synchronization signal (e.g. for random access) in a beamformed fashion and swept through the angular area (e.g. in azimuth or elevation). Each DL synchronization beam 305 can be transmitted in a beam sweeping operation, in different directions, to cover the area covered by base station 105b. For example, DL synchronization beacon 305a can be transmitted in a first direction. DL synchronization beacon 305b may be transmitted with a beam sweeping operation in a second direction. DL synchronization be 305b may be transmitted with a third direction. DL synchronization be 305c may be transmitted with a fourth direction. System 300 may show four DL synchro beams 305. However, it should be understood that there could be fewer or more DL sync beams 305. The DL synchronization beams 305 can be transmitted at different beam widths and at different elevation angles. In certain aspects, DL synchronization beacons 305 can be associated with a beam indicator, such as an indicator identifying the beam.
In some cases, DL synchronization beacons 305 can be transmitted at different symbol periods within a synchronization subframe. DL synchronization beacon 305a can be transmitted in a first symbol time (e.g. symbol 0), DL synchronization beacon 305b may be transmitted in a second symbol time (e.g. symbol 1), DL synchronization be 305b may be transmitted in a third symbol phase (e.g. symbol 2), DL synchronization be 305c may be transmitted within a fourth symbol interval (e.g. symbol 3). Additional DL synchroization beams 305 can be transmitted during additional symbol periods in the synchronization subframe.
“Generally, the beam sweeping operation supports basestation 105-b in determining which direction UE 115 b is located (e.g. after receiving response messages for UE 115 b). This allows transmission of RACH message 2 via base station 105 -b. The beam sweeping operation also improves communication when correspondence is not held between DL channels and UL channels. UE 115b may select the frequency area and/or waveform configuration (e.g. resource and/or RACH) to transmit the random access signal (e.g. RACH message, RACH msg1, RACH msg3, RACH msg3) based upon the index of the preferred or best DL synchronization signal from the DL synchronization beam 305. UE 115-1a may transmit the preferred or best DL beam by using an identification or index in a RACH msg1. Base station 105-a can find the appropriate UL beam during the random access period by receiving the random signal in a sweeping fashion. Base station 105b may identify the UE 115 -a selected DL beam using the resource and/or RACH wavesforms used (e.g. the frequency region and/or configuration used) that contain the RACH message (e.g. RACH msg1 and RACH msg3).
“UEs located within the coverage area 105-b can receive the DL synchronization signal on DL synchronization beams 305. The UE 115b can identify the best DL synchronization signal (e.g. strongest received signal strength, highest channel quality, etc.). ), and identify it as the selected DL beam. UE 115-b can then choose a resource or RACH waveform to transmit the RACH message based upon the selected DL beacon, such as the preferred DL beam. One example is that the RACH message resource and/or RACH waveform used to transmit the RACH message could correspond with the symbol of the selected DLB beam. Another example is that the RACH message could include an index or identification of the preferred beam.
“Although 16 DL beams are possible, this is a non-limiting example. UE 115b could use four bits to transmit the DL beam information from base station 105b. UE 115 b may have four subcarrier areas (e.g. resources) and four RACH waveforms. UE 115b can transmit four bits using one of the four RACH waveforms, and one of four subcarriers. UE 115b could choose to send the RACH message from base station 105b using a combination of the resource waveform and the RACHwaveform.
“In certain aspects, system 300 may allow UE 115 to select a combination from a RACH waveform or the resource used for its RACH messaging transmission based on one of several combinations of an index of a DL synchronization beacon or a symbol in the DL synchronization subsection. UE 115b can transmit random access signals (e.g. RACH message or RACH msg1 and RACH msg3) throughout the duration of the random acces subframe, and/or during a part of that random access subframe.
“Base station 105-b can determine the selected DL beam for UE 115 based on the frequency region and/or RACH waveform which contain the message 1 random access signal. Base station 105b can determine the best UL receiver beam by measuring the quality at different uplink receiver beams. Signal quality can be defined as RSRP, RSSI or RSRQ.
“UE 115-b could select the best DL synchronization signals and the frequency region for RACH and/or RACH waveforms based on the index the best DL synchronization signals. UE 115b may choose a DL synchronization beacon 305 that meets a transmit power condition. UE 115b may choose a RACH preamble or cyclic shift partly based on the index for a DL synchronization beacon 305.
“The absence or inconsistency of correspondence could indicate that the best DL beam beam and the best UL beam may not be the same.”
“UE 115-b can select a combination RACH and the resource used to transmit it based on a symbol in the DL synchronization underframe if base station 105 -b transmits multiple beams using multiple antenna port symbols within each symbol. The resource can be used to denote component carriers and/or component carriers.
“Even though the example is described in FIG. While the example in FIG. 3 is for transmitting RACH messages in a RACH Subframe, it can also be used to transmit a scheduling request message or beam recovery message within a RACH Subframe. UE 115 might find that the best synchronization beacon was transmitted during a particular symbol. In these cases, UE 115 could transmit a scheduling request, beam recovery message or beam tracking message in a frequency area that corresponds with the symbol. A different resource (or resource block in a RACHsubframe) may contain the frequency region. This means that a portion of a RACH Subframe’s resources may be used for RACH message transmissions. A second portion of a RACH Subframe might be used for scheduling request message transmissions. Finally, a third portion may be used for beam recovery and beam tracking message transmissions.
“UE 115b” may be able to receive an indication about the subcarrier area for a scheduling request message or beam recovery message transmission via RRC signaling. There may be eight (8) subcarrier regions in some cases. UE 115b may also be able to receive the desired cyclic shifting for the scheduling request message or the beam recovery/beam tracking message transmission via RRC signaling. UE 115b might use twelve (12) different cyclic shiftings to generate a sequence of the scheduling request message transmission, beam recovery, or beam tracking message message transmission. There may be more available cyclic shifting options for scheduling request message transmissions or beam recovery and beam tracking message transmissions than there are available cyclic shifts to transmit a RACH message transmission. This is because UE 115b may correct a timing error before transmitting the scheduling request message transmission. The transmission of the scheduling request message or the beam recovery, or beam tracking message, may be spread across two (2) symbols, which could provide additional degrees (e.g. 192 degrees in each symbol pair).
“FIGS. 4A and 4B show examples of a beam subframe mapping configuration 400 for RACH conveyance DL synchronization beam info for various DL?UL correspondence states. Configuration 400 could implement aspects of wireless communication network 100, process flow 200, and/or system 300 if FIGS. 1. through 3. In certain aspects, configuration 400 may be implemented using a base station 105 or a UE 115. Refer to FIGS. 1. through 3.
“With reference to FIG. “With reference to FIG. Base station 105 can transmit DL synchronization signal (e.g. for random access) in a beamformed fashion and swept through the angular coverage area (e.g. in azimuth or elevation). Each DL synchronization beam 405 may be transmitted in a beam sweeping operation in various directions in order to cover the area covered by base station 105. For example, DL synchronization beacon 405-a can be transmitted in a single direction. DL synchronization beacon 405-b, on the other hand, may be transmitted with a beam sweeping operation in a different direction to cover the coverage area of base station 105. In certain aspects, DL synchronization beacons 405 can be associated with a beam indicator, such as an indicator identifying the beam.
“In certain aspects, DL synchronization beacons 405 can also be transmitted during different symbol times of a synchronization -frame 410. The synchronization subframes 410 can be associated with a time feature (e.g. symbols) along the horizontal axis and a frequency feature (e.g. frequencies or tones) along the vertical. For example, DL synchronization beacon 405-a can be transmitted in a first symbol period (e.g. symbol 0), DL synchronization beacon 405b may be transmitted in a second symbol time (e.g. symbol 1), and so forth until DL synchronization be 405-h is transmitted in an eighth symbol period.
“In certain aspects, each DL synchronization signals transmitted on a DL synchronization beacon 405 may be transmitted at any frequency during the symbol. For example, DL synchronization beacon 405-a can be transmitted on frequency 0-7 during symbol 0. DL synchronization beacon 405-b could be transmitted on frequency 0-7 during symbol 1.
“Base station 105 can sweep DL synchronization beams 405, in eight directions, during eight symbols of synchronization subframe 410.”
“With reference to FIG. 4B: UEs 115 located within the coverage area 105 can receive the DL synchronization signal on DL synchronization beams 405 The UE 115 can identify the best DL synchronization signal (e.g. strongest received signal strength, highest channel quality, etc.). ), and this is the selected DL beam. FIG. 4B, the UE 115 identified the DL synchronization signal transmitted by DL synchronization beam 405-b as the selected DL beacon. As you can see, DL synchronization beacon 405-b was transmitted during symbol 2.
“UE 115 may select a resource for transmission of RACH message based upon the selected DL beam. One example is that the symbol of the selected DL bee may be used as the resource for transmitting the RACH message. UE 115 could choose the second resource 420 (e.g. frequency or tone 1) to transmit the RACH message. UE 115 could choose to use the second resource 420 in order to indicate the DL synchronization beam transmitted by the second symbol as the selected DL beam. As mentioned above, UE 115 could also choose a RACH waveform in order to transmit the RACH message.
“UE 115 might find that the best synchronization beam was transmitted during a second symbol. UE 115 could transmit a RACH message at the second frequency for all time slots (e.g. during all symbols in the RACH subframe 415). Base station 105 might find the best DL transmit beam in the used frequency region (e.g. second resource 420) from the random access signal (e.g. RACH message). Due to DL-UL power difference differences, some RACH message transmission times units might be longer than the synchronization time units in certain cases.
“Base station 105 could sweep the same eight directions in the RACH subframe 405. Base station 105 could configure one or more antenna arrays in order to receive the RACH message using the same sweeping pattern used to transmit the DL synchronization signals on the DL synchronization beams 405.
“The above example with reference to FIG. 4. may be applicable to cases where there is no correspondence at base station 105 regarding the selected DL beam. The example could also be applicable to cases where there is no correspondence between base station 105, UE 115. UE 115 might identify a way to transmit using the selected DL beacon based on a linkgain associated with transmissions from UE 115. In certain cases, UE 115 might determine its link gain based upon synchronization signals from base station 105. UE 115 can transmit the RACH message within a single RACH frame if it has sufficient link gain to meet a link budget. UE 115, however, may transmit the RACH message to multiple RACH subframes if UE 115 doesn’t have enough link gain to meet a link budget.
“The example is described in reference to FIGS. While 4A and 4B are intended for transmitting RACH messages in RACH 415, the example can also be used to transmit a scheduling request message or beam recovery message in RACH 415. UE 115 might find that the best synchronization beacon was transmitted during the second symbol. In these cases, UE 115 could transmit a scheduling request, beam recovery message or beam tracking message in a different frequency region for all times slots. The second frequency area may be located in a different resource (or block) in RACH 415. This means that a portion of RACH 415 resources may be used for RACH message transmissions. A second portion of RACH 415 resources may be used for scheduling request message transmissions. Finally, a third portion may be used for beam recovery and beam tracking message transmissions.
“FIGS. 5A and 5B show an example beam-subframe mapping configuration 500 to enable RACH conveyance DL synchronization beam data for different DL-UL correspondence states. Configuration 500 could implement aspects of wireless communication 100, process flow 200, and/or system 300. 1. through 3. In certain aspects, configuration 500 can be implemented using a base station 105 or a UE 115. Refer to FIGS. 1 through 3.
“With reference to FIG. “With reference to FIG. Base station 105 may transmit DL synchronization signal (e.g. for random access) in a beamformed fashion and swept through the angular coverage area (e.g. in azimuth or elevation). Each DL synchronization beacon 505 can be transmitted in a beam sweeping operation in a different direction to cover the area covered by base station 105. For example, DL synchronization beacon 505-a can be transmitted in a single direction. DL synchronization beacon 505-b, on the other hand, may be transmitted with a beam sweeping operation in a different direction to cover the coverage area of base station 105. In certain aspects, DL synchronization beacons 505 could be associated with a beam indicator, such as an indicator identifying which beam.
“In certain aspects, DL synchronization beacons 505 can also be transmitted during different symbol times of a synchronization frame 510. The synchronization subframe510 can be associated with a time feature (e.g. symbols) along the horizontal axis and a frequency feature (e.g. frequencies or tones) along the vertical. FIG. FIG. 5A shows base station 105 with four antenna arrays. Base station 105 can sweep four directions for each symbol. Antenna ports 0-3 could be grouped in subgroup 510 to transmit DL synchronization beacons 505a through 505d during the first symbol (e.g. symbol 0) within the synchronization subframe 510. Antenna ports 0-3 can be grouped in subgroup 515 to transmit DL synchronization beacons 505?e through 505?h during the second symbol (e.g. symbol 1) of synchronization subframe 510. Base station 105 can sweep eight directions in two symbols of synchronization subframe510.
“In certain aspects, each DL synchronization signals transmitted on a DL synchronization beacon 505 may be transmitted at any frequency during the symbol. DL synchronization beacon 505-a can be transmitted on any frequency or tone 0-7 during symbol 0. DL synchronization beacon 505-b can be transmitted on any frequency or tone 0-7 during symbol 1. The DL synchronization beacons 505 that are transmitted during a symbol might not be transmitted on overlapping frequencies in certain aspects.
“Base station 105 can sweep DL synchronization beams 505 in eight directions during eight symbols within the synchronization subframe 510.”
“With reference to FIG. 5B: UEs 115 in the coverage area of basestation 105 can receive the DL synchronization signal on DL synchronization beams 5005. The UE 115 can identify the best DL synchronization signal (e.g. strongest received signal strength, highest channel quality, etc.). ), and this is the selected DL beam. FIG. 5B shows an example. FIG. 5B shows that the UE 115 identified the DL synchronization signal received on DL synchronization beam 5005-a as the selected DL beacon. As noted, DL synchronization beacon 505-a was transmitted during symbol 1 (e.g. symbol 0).
“UE 115 may select a resource for transmission of RACH message based upon the selected DL beam. One example is that the symbol of the selected DL bee may be used as the resource for transmitting the RACH message. UE 115 could choose the first resource 520 (e.g. frequency or tone 0), as the resource to transmit the RACH message. UE 115 could choose to transmit the RACH message to the first resource 520 in order to indicate the DL synchronization beam transmitted by the first symbol.
“UE 115 might find that the best synchronization beam was transmitted in the first symbol. UE 115 could transmit a RACH message during the first frequency area for all time slots (e.g. all symbols in the RACH subframe 555). Base station 105 might determine the best UL received beam by measuring how the signal is received during different times slots (e.g. during different symbols). Base station 105 might find the best course of DL beam in certain aspects by measuring the quality of the received signal during different time slots (e.g. during different symbols).
“Base station 105 could sweep the same eight directions in the RACH subframe 515.” Base station 105 could configure one or more antenna arrays in order to receive the RACH message using the same sweeping pattern used to transmit the DL synchronization signals on the DL synchronization beams 505 during the synchronization subframe 510.
“FIGS. 6A and 6B show examples of a beam subframe mapping configuration 600 for RACH conveyance DL synchronization beam info for different DL-UL correspondence state. Configuration 600 could implement aspects of wireless communication network 100, process flow 200, and/or system 300, if FIGS. 1. through 3. Some aspects of configuration 600 can be implemented by a basestation 105 or a UE 115 in certain cases, as described with reference to FIGS. 1. through 3.
“With reference to FIG. “With reference to FIG. Base station 105 may transmit DL synchronization signal (e.g. for random access) in a beamformed fashion and swept through the angular coverage area (e.g. in azimuth or elevation). Each DL synchronization beam 605 can be transmitted in a beam sweeping operation in various directions to cover base station 105’s coverage area. DL synchronization beacon 605-a, for example, may be transmitted in a single direction. DL synchronization beacon 605-b, on the other hand, may be transmitted with a beam sweeping operation in a different direction to cover the coverage area of base station 105. In certain aspects, DL synchronization beacons 605 could be associated with a beam indicator (e.g. an indicator identifying which beam).
“In certain aspects, DL synchronization beacons 605 can also be transmitted during different symbol times of a synchronization frame 610. The synchronization subframe610 can be associated with a time feature (e.g. symbols) along the horizontal axis and a frequency feature (e.g. frequencies or tones) along the vertical. DL synchronization beacon 605-a can be transmitted in a first symbol period (e.g. symbol 0), DL synchronization beacon 605b may be transmitted in a second symbol period, e.g. symbol 1, and so on, until DL synchronization be 605-h is transmitted in an eighth symbol period.
Summary for “Rach conveyance DL synchronization beam info for different DL-UL correspondence states
“The following applies generally to wireless communication and, more specifically, to random access channel (RACH), conveyance of downlink information (DL) for various downlink?uplink (DL?UL) correspondence states.
Wireless communications systems are used to transmit various communication types, including voice, video, packet data and messaging. These systems can support communication with multiple users by sharing system resources (e.g. time, frequency and power). Multiple-access systems can include code division multiple acces (CDMA), time division multiple accessibility (TDMA), frequency division multipleaccess (FDMA), and orthogonal frequency division multiple access systems (OFDMA), such as a Long Term Evolution system (LTE). Wireless multiple-access communication systems may have a number base stations that support communication with multiple communication devices. These communication devices may also be known as user equipment (UE).
Wireless communication systems can operate at millimeter-wave (mmW), frequency ranges (e.g. 28 GHz, 40 GHz, 60 GHz, etc.). These frequencies can cause increased signal attenuation (e.g. path loss) which could be affected by temperature, barometric pressure and diffraction. Signal processing techniques such as beamforming can be used to combine energy coherently and overcome path losses at these frequencies. Transmissions from the UE and base station may be beamformed due to increased path loss in mmW communications systems.
Wireless communications between two wireless nodes (e.g. between a base station, UE) may use beams, or beam-formed signals to transmit and/or receive. A base station can transmit beamformed synchronization signal on downlink (DL), synchronization beams. A synchronization signal may be received by a UE on one or more DL synchronization beams. This will allow the UE to initiate a RACH procedure. Sometimes, the UE might send a message to base station as part the RACH procedure. The base station may assume the uplink beam (UL) on which the RACH message was received is representative for a DL beam that should be used by the base station in communicating with the UE. The base station assumes that DL-UL correspondence is being exchanged. For various reasons, however, the correspondence between DL channel channel and UL channel could be missing. The base station assumption could be wrong, and the DL beam chosen by it may not be the best beam to communicate with the UE.
“The techniques described herein relate to improved methods and systems, devices, and apparatuses that support RACH conveyance DL beam information for different DL-UL correspondence states. The described techniques allow a base station transmit DL signals to an UE. The DL signals can be transmitted via DL beam(s). The UE can use the DL beam of the DL beams that can be used to communicate with the base station (e.g., DL communication). For transmission of a RACH message (e.g. RACH msg1), the UE can select a resource or random access channel (RACH), waveform. The UE may choose the RACH or resource waveform based upon the DL beam. The UE can transmit to the base station the RACH message on the selected resource or the RACH waveform. The RACH message may be received by the base station on the resource or the RACHwaveform. It will identify the DL beam that the UE selected based on the resource or the RACHwaveform. For subsequent communications with UE, the base station can use the selected DL beam.
“A method for wireless communication” is described. This could include receiving a DL message from a base station on one, or more DL beacons, identifying a selected DL beam of the one or many DL beams for communications between the UE and the base station, and sending a RACH message/scheduling message/beam tracking message to the base stations using at least one resource or a waveform chosen based at most in part on the selected DLbeam.
“A wireless communication apparatus is described. The apparatus can include means to receive a DL signal on a base station’s one or more DL beacons, means to identify a selected DL beam of the one/more DL beams for communications between the base station and the UE, and means to transmit a RACH message/scheduling message/beam tracking message to the base stations using at least one resource or a waveform chosen based at most in part on the selected DL-beam.
“Another apparatus is described for wireless communication. The apparatus can include a processor and memory for electronic communication with it. Instructions may be stored in the memory. Instructions may be used to instruct the processor to send a DL signal to a base station on one, more or all DL beams. The processor will then identify a selected DL beacon of the one or many DL beams to transmit a RACH message/scheduling message/beam tracking message to the UE using at least one resource or a waveform chosen based at most in part on the selected DL-beam.
A non-transitory computer-readable medium for wireless communication has been described. Instructions may be included that allow a processor to detect a DL signal coming from a base station, to identify a selected DL beacon of the one or multiple DL signals for communications between the UE and the base station, and to transmit a RACH message/scheduling message/beam tracking message to the base stations using at least one of a resource, or a waveform chosen based at most in part on the selected DL-beam.
“In some cases of the non-transitory computer readable medium, apparatus and method described above, the waveform includes one of a scheduling request, or a RACHwaveform.”
“In some cases of the non-transitory computer readable medium, apparatus and method described above, the digital signal DL comprises either a synchronization signal, or a reference signal.”
“In some cases of the non-transitory computer readable medium, apparatus and method described above, the selected resource/waveform includes: Selecting the resource or waveform based at most in part on the index of the selected DLB beam. The selected resource or waveform is described in some of the above-described methods, apparatuses, and non-transitory computers-readable media.
“In some cases of the method, apparatus and non-transitory computers-readable medium described above transmitting the RACH/scheduling message/beam recover or beam tracking messages comprises: transmitting RACH/scheduling message/beam recuperation or beam tracking message for the entire duration of a corresponding random acces subframe. The following examples illustrate the non-transitory computerreadable medium, apparatus and method. The process of identifying the preferred DL beacon is performed.
“In some cases of the non-transitory computer readable medium, apparatus and method described above, identifying a selected DL beam involves: Identifying the DL beacon based at minimum in part on the DL signal from one or more DL beams that meet a transmit power condition. The non-transitory computer readable medium, apparatus and method described above may also include methods, features, or instructions to select the resource/RACH waveform for transmission/scheduling request/beam recovery/beam tracking message to base station. The selected DL beam is used as the basis for the RACH waveform or resource being selected.
“Some examples of the non-transitory computer readable medium, apparatus and method described above include selecting the RACH waveform by selecting a RACH preamble or a cyclic shifting, or any combination thereof, determined at least partially on the index of the selected beam. One or more DL transmit beams may not be received at the base station from one or more UL receiver beams. This could occur in some instances of the apparatus, method, and non-transitory information-readable medium. It is possible that the absent correspondence could be due to the one or two DL transmit beams with different beam directions than one or more UL receiver beams.
“Some examples of the non-transitory computer readable medium, apparatus and method described above may also include features, means or instructions for identifying correspondence that is absent by receiving information at the base station in a master or system information block.
“Some examples of the non-transitory computer readable medium and method described above may also include processes, features and means or instructions for selecting the resource. These can be based at minimum in part on identification of the missing correspondence and transmitting the RACH message/scheduling message/beam recuperation or beam tracking message (for the entire duration of a RACH Subframe) based at most in part on the absence of the correspondence. The method, apparatus and non-transitory computer readable medium may also include instructions, features, or means for selecting the resource/RACH waveform, at least partially based on the absence of correspondence.
“Some of the non-transitory computer readable media, apparatus and method described above may also include features, means or instructions for receiving the absence of correspondence in a master or system information block. The non-transitory computer readable medium and apparatus described above could also include instructions, processes, features, or means for transmitting a signal that there is no correspondence between one or more DL beams coming from the base station or one or two UL beams coming from the UE. The non-transitory computer readable medium and the method described may also include the following: processes, features and instructions to transmit the RACH message/scheduling message/beam rescue or beam tracking message from the base station during the first symbol of a first random acces subframe and the second symbol of another random access subframe. The non-transitory computer readable medium and the method described above could also include the following: processes, features, methods, or instructions to transmit the absence of correspondence in a RACH 3 message, a physical control channel (PUCCH), a physical shared channel (PUSCH), or a PUCH).
“Some of the non-transitory computer readable media, apparatus and method described above may also include features, means or instructions for receiving information about a nature or correspondence between one or more DL beams at the base station and one, or more UL beams at the UE. The nature of correspondence can correspond to any of the following: partial correspondence, full correspondence or none.
“Some examples of the non-transitory computer readable medium and method described above may also include features, means or instructions for determining whether correspondence is present. This can be done based upon the nature of the correspondence and selecting a transmission date for sending the RACH message/scheduling message/beam recuperation or beam tracking message to base station. The transmission time may include a symbol for a corresponding random-access subframe. The apparatus, method, and non-transitory computer readable medium described may also include features, means, or procedures for determining if there is partial correspondence. These can be based on an indication of the nature and choosing a transmission time to transmit the RACH message/scheduling message/beam recuperation or beam tracking message. Some examples include multiple symbols from a corresponding random-access subframe as part of the transmission time.
“Some of the non-transitory computer readable media described above may also include features, means or instructions for selecting a transmission frequency range and a transmission time. The non-transitory computer readable medium and apparatus described above may also include instructions, features, or means for selecting the resource. These can be based at minimum in part on the symbol associated with the DLS signal, as well as the indication of the nature and content of correspondence. The non-transitory computer readable medium, as well as the apparatus, may also include the following: processes, features and means or instructions for receiving the information about the nature of correspondence via a physical broadcast channel (PBCH), or an extended (ePBCH). The method, apparatus and non-transitory computers-readable medium may also include instructions, features, means or processes for receiving the information about the nature of correspondence in a MIB, a SIB, or other types.
“In some cases of the method, apparatus and non-transitory computers-readable medium described above the selected DL beam may differ from a selected UL beacon from the UE. The one or more DL beacons from the base station may not be contained within the same symbol of a synchroization subframe. In these cases, selecting the resource for the transmission of the scheduling request messages involves selecting the waveform or resource based at most in part on the symbol associated with the selected DL beam.
“In some cases of the non-transitory computer readable medium and method described above, the resource could be associated with one or several tones in a component carriers. The resource can be associated with a component carrier in some of the above-described methods, apparatuses, and non-transitory computers-readable media. The non-transitory computer readable medium, apparatus and method described above could also include features, means or instructions to select a combination of the resource or the RACH waveform in order to transmit the RACH message/scheduling message/beam recuperation or beam tracking message to base station.
“A method for wireless communication” is described. This may involve transmitting a DL message on one or several DL beacons, receiving from a UE a RACH message/scheduling message/beam recover or beam tracking message.
“A wireless communication apparatus is described. The apparatus can include means to transmit a DL signal using one or multiple DL beams, as well as means to receive, on at most one of a resource/beam recovery message/beam tracking message, a RACH message/scheduling message/beam tracking message from a UE.
“Another apparatus is described for wireless communication. The apparatus can include a processor and memory for electronic communication with it. Instructions stored in the memory may also be included. Instructions may be used to instruct the processor to transmit a DL message on one or several DL beams, to receive on at least one of a resource/beam recovery message/beam tracking message from a UE and to identify, based at minimum in part on the resource/waveform, a selected DL beacon of the one/more DL beams for communications between the base station and the UE. The selected DL beam can then be used to transmit one or multiple subsequent messages to the UE
“A non-transitory computer-readable medium for wireless communication” is described. Instructions may be included that allow a processor to transmit a DL message on one or several DL beams, to receive on least one of a resource/beam recovery message or beam tracking message from a UE and to identify, based at minimum in part on the resource/the waveform, a selected DL beacon of the one/more DL beams for communications between the base station and the UE. The selected DL beam can then be used to transmit one or multiple subsequent messages to the UE
“In some cases of the non-transitory computer readable medium and the method described above, identifying a selected DL signal consists of associating the waveform or resource with an index of that selected DL beam. In some cases, the apparatus and non-transitory computer readable medium are described as: Associating the resource/waveform with a symbol from a subframe in the DL signal.
“In some cases of the method, apparatus and non-transitory computers-readable medium described above receiving the message/scheduling message/beam recover or beam tracking messages comprises: receiving the message/scheduling message/beam recuperation or beam tracking message for the entire duration of the corresponding random access frame. Some examples of the method, apparatus and non-transitory computers-readable medium mentioned above include: Receiving the RACH/scheduling message/beam recover or beam tracking messages on a plurality UL beams.
“Some examples of the non-transitory computer readable medium and method described above may also include processes, features or means or instructions for measuring a quality RACH message/scheduling message/beam recovery message or beam tracking message received on a plurality of UL beams. The method, apparatus and non-transitory computers-readable medium may also include features, means or instructions to determine a specific UL beam for communications between the UE and the base station based at most in part on its quality.
“Some examples of the non-transitory computer readable medium and method described above include: measuring one or more reference signals received power (RSRP), received signal strength indicator(RSSI), reference signal received quality [RSRQ]), signal to noise ratios (SNR) or signal to interference plus noisy ratio (SINR). The method, apparatus and non-transitory computer readable medium described above include the following: Identification of the selected DLB beam is done based at minimum in part on the resource/waveform of the RACH/scheduling request/beam recovery/beam tracking message.
“In some cases of the non-transitory computer readable medium, apparatus and method described above, identifying a selected DL beacon consists of: identifying the selected DL bead based at minimum in part on a RACH Preamble of RACH message, a cyclic shifting of RACH message or combinations thereof. The method, apparatus and non-transitory computers-readable medium described in some cases lacks correspondence between one or several DL beams from base station and one (or more) uplink beams at base station. In these cases, the absent correspondence is associated to the one, two, or more of the DL beams with different beam directions than one or multiple UL beams.
“Some of the non-transitory computer readable media, apparatus and method described above may also include features, means or instructions to identify that correspondence is absent between one or more DL beams at the base stations and one or two uplink (UL), beams at the station.”
“Some of the non-transitory computer-readable media described above may also include features, means or instructions for receiving an indicator that there is no correspondence between the one or two DL beams at the base station and one, or more UL beacons from UE and mapping DL bes used in transmitting channel state information (CSIRSs) to UL beams to transmit sounding references signals (SRSs) or mapping ULbes used by to transmit sounding refer signals (SRSs) to DL-channel state information (CSI-RSs to transmitting channel state information (CSI-reference signals) to DL beams to send channel state information (CSI-res to CSI-s to a channel state information (CSI-line information to CSI-s to DL beams to DL beams to s to DL to CSI-state information to s to s to s to s to s to s to s to s to s to s to DL beams to DLs to s to s to s to s to s to s to s to s to s The non-transitory computer-readable media described above could also include the following: processes, features and instructions to receive an indication that there is no correspondence between the one or two DL beams at the base station and one of the UL beams at the UE, mapping UL beacons used to transmit sounding reference signals (SRSs) to DL beams which are used to transmit channel state information reference signals (CSI-RSs), or mapping UL beams to UL beams to DL beamed in UL training, or mapping UL beams to UL beams to UL beams to UL beams to UL beams to UL beams to UL beams UL beams to UL beams to UL beams to UL beams to UL beams to UL beams in UL beams to DL beams to UL beams to DL beams to UL beams to UL beams to UL beams to UL beams to UL beams to DL beams to UL beams to UL beams to UL beams to DL beams to UL beams to DL beams to UL beams to UL beams UL beams to DL beams to DL beams to DL beams to DL beams to DL beams to DL beams to UL beams to DL to DL to DL to DL to DL to DL to DL to DL to DL to DL to s used in DL to DL to DL to DL to DL to DL to DL to DL to DL to DLs used in DL to DL to DL to DL to DL to DL to DL to DL to DLs used in to DL to DL to DL to DL to DL to DL beams to DL to DL to DL to DL to DL beams to DL to DL to DL to DL beams to DL to DL to DL to DL to DL to DL to DL to DL to DL beams to DL to DL to DL be to DL to DL to DL to DL to
“In some cases of the apparatus, method, and non-transitory computer readable medium described above, the selected DL beacon from the base station might be different than a selected UL beam coming from the UE. The resource could be associated with one or several tones in a component carrier, depending on the example of the apparatus and non-transitory information-readable medium. The resource could be associated with a component carrier in some of the above-described examples of the apparatus, method, and non-transitory computing medium.
The carrier frequency may cause a greater loss of free space. Transmission in millimeter-wave (mmW) systems could also be affected by non-line of sight losses (e.g., penetration loss and oxygen absorption loss, leaf loss, and so on). These high path losses may be overcome by the base station and user equipment (UE) during initial access to detect or discover each other. The present disclosure provides improved access to mmW systems.
“Aspects disclosed are first described in the context a wireless communication system. The described techniques allow a UE (user equipment) to indicate to a base station a selected downlink beam (DL), by selecting a corresponding resource (RACH waveform) for transmission of a RACH/scheduling request/beam recovery/beam tracking message. The base station might transmit DL signal(s), on DL beam(s). The UE might select a DL beam that can be used to transmit DL signals (e.g. from the base station to UE). The UE can select a resource or a waveform (e.g. a RACH waveform, a scheduling request waveform, or a RACH message) to transmit the RACH message/scheduling message/beam recovery or beam tracking message from the base station. Selection is based upon the selected DL beam. The UE can then transmit the RACH message/scheduling message/beam recover or beam tracking message using the selected resource/or RACHwaveform to the base station. The base station then receives the RACH message/scheduling message/beam recover or beam tracking message using the selected resource/or RACHwaveform. It uses the resource/or RACHwaveform to identify the selected beam. The UE can select a resource (e.g. channel) that corresponds with the timing feature of the DL signals (e.g. symbol). The selected DL beam may be used by the base station for communications between the base station and the UE (e.g. for future DL communications). A resource can be a time resource or a frequency resource in some cases.
“Aspects are further illustrated and described by reference to apparatus diagrams and system diagrams and flowcharts that pertain to RACH conveyance DL synchronization beam info for different DL-UL correspondence states. In some cases, correspondence could refer to reciprocity.
“FIG. “FIG. 1 illustrates a wireless communication system 100 according to various aspects of this disclosure. Wireless communications system 100 comprises base stations 105 and UEs 115 as well as a core network 130. The wireless communications system 100 could be either an LTE (or LTE Advanced) network in some cases.
“Base stations 105 can wirelessly communicate with UEs 115 using one or more base station antennas. Each base station 105 can provide coverage in a specific geographic area 110. The wireless communications system 100 shows communication links 125. These may include UL transmissions between a UE 115 and a base stations 105 or DL transmissions between a UE 115 and a UE 115. UEs 115 can be distributed throughout wireless communications system 100. Each UE 115 could be mobile or stationary. A UE 115 can also be called a mobile station or subscriber station. Each UE 115 could be stationary or mobile. A UE 115 could also refer to a cellular phone or a personal digital assistant (PDA), a wireless device, a wireless communication device and a handheld computer, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a client, a client, or some other suitable terminology.
“Base stations may communicate with each other and the core network 130. Base stations 105, for example, may communicate with the core network 130 via backhaul links 132, (e.g. S1, etc.). Base stations 105 can communicate over backhaul link 134 (e.g. X2, etc.). Either directly or indirectly (e.g. through core network 130). Base stations 105 can perform radio configuration and scheduling to communicate with UEs 115. They may also operate under the control a base station controller (not illustrated). Base stations 105 can be macro cells, small cell, hot spots or other types depending on the situation. Base stations 105 can also be called eNodeBs (eNBs 105).
“During an initial access procedure (also referred to as a RACH procedure), UE 115 can transmit a RACH preamble from a base station 105. This could be called RACH message 1. The RACH preamble could be randomly chosen from 64 predetermined sequences. This could allow the base station 105 distinguish between multiple UEs 115 trying access the system simultaneously. The base station 105 might respond by sending a random access request (RAR), also known as RACH message 2, which provides an UL resource grant and a timing advance. It may also provide a temporary mobile radio network temporary identification (C-RNTI). If the UE 115 is previously connected to the same wireless network, the UE 115 could transmit a radio resource control (RRC), connection request or RACH message 3. Radio resource control (RRC), connection requests may indicate why the UE 115 connects to the network (e.g. emergency, signaling or data exchange). The base station 105 might respond to the connection request by sending a RACH message 4 to the UE 115. This message may contain a contention resolution message or RACH message 4. It may also provide a new CRNTI. The UE 115 can proceed with RRC setup if the UE 115 is able to receive a contention resolution message that contains the correct identification. The UE 115 can continue with RRC setup if it does not receive a contention message (e.g. if there is a problem with another UE 115).
“Wireless communication network 100 may operate in an ultrahigh frequency (UHF), frequency region that uses frequency bands ranging from 700 MHz up to 2600MHz (2.6GHz), though in some cases WLAN networks can use frequencies as high at 4GHz. The decimeter band may also be called this region, as its wavelengths are approximately one to one meter long. UHF waves can propagate mostly by line-of-sight, but may be blocked by buildings or other environmental features. The waves can penetrate walls enough to provide service to UEs 115 indoors. Transmission of UHF waves has a shorter range and smaller antennas than transmission using the higher frequencies (and longer waves), portion of the spectrum. Wireless communication system 100 can also use extremely high frequency (EHF), portions of the spectrum in certain cases (e.g. 30 GHz to 300GHz). This area may also be called the millimeter spectrum, as it has wavelengths that range from one millimeter up to one centimeter long. EHF antennas can be smaller and less spaced than UHF antennas. This may allow for the use of an antenna array within a UE 115 in certain cases (e.g. for directional beamforming). EHF transmissions can be subject to greater atmospheric attenuation, and may have a shorter range than UHF transmissions.
“Specifically, wireless communication system 100 can operate in mmW frequency bands (e.g. 28 GHz, 40 GHz, 60 GHz etc.). These frequencies can cause increased signal attenuation (e.g. path loss) which can be affected by temperature, barometric pressure and diffraction. Signal processing techniques, such as beamforming, can be used to combine signal energy coherently and eliminate path loss in certain beam directions. A device such as a UE 115 may choose a beam direction to communicate with a network. This is done by choosing the strongest beam among a variety of signals transmitted from a base station 105. One example is that the signals could be DL synchronization signal (e.g. primary or secondary synchronizations signals) or DL references signals (e.g. channel state information reference signs (CSI-RS),) transmitted from base station 105 during discovery. For example, the discovery procedure can be cell-specific and directed in incremental directions within the coverage area 110 at the base station 105. In certain cases, the discovery procedure can be used to identify and select beams to be used in beamformed transmissions between a UE 115 and base station 105.
“Base station antennas can sometimes be found within an antenna array. An antenna tower, or one or more base station antennas, may have multiple antenna arrays. Antennas and antenna arrays that are associated with base station 105 can be found in different geographic locations. An antenna array or multiple antennas may be used by a base station 105 to perform beamforming operations in order to transmit directional information with a UE 115.
“Wireless communication 100 could include or be multicarrier mmW wireless communications system. A number of aspects of wireless communication systems 100 could include a UE 115 or a base station 105 that can be configured to support RACH conveyances of DL synchronization beam data for different DL-UL correspondence states. The base station 105 might transmit DL signal(s), on DL beam(s). The UE 115 could select a DL beam that can be used to transmit DL signals (e.g. from base station 105 to UE 115). The UE 115 can select a resource or a RACH waveform to transmit the RACH message from the base station 105. Selections are based on the selected DL beacon. The UE 115 can then transmit the RACH message from the base station 105 by using the selected resource or RACH waveform. The base station 105 then receives the RACH message using the selected resource or RACH waveform. It uses the resource and/or the RACH waveforms to identify the selected DL beacon. The UE 115 can select a resource (e.g. channel) that corresponds with the timing feature of the DL synchronization signals (e.g. symbol). The selected DL beam may be used by the base station 105 for communications between the UE 115 and the base station 105 (e.g. for future DL communications).
“FIG. 2. This is an example of a process flow 200 to transmit DL synchronization beam data for different DL-UL correspondence states. Process flow 200 could implement aspects of wireless communications system 100 as shown in FIG. 1. Process flow 200 could include a UE 115a and a basestation 105a. These may be examples of the corresponding devices in FIG. 1. Base station 105a could be a mmW station or a serving station for UE 115a.”
“At 205 base station 105-a might transmit information about correspondence related to DL beams at base station side. In certain aspects, base station 105 may indicate correspondence with UE 115.a. One example is that a bit could be used to transmit the correspondence indication. Base station 105-a could implicitly indicate correspondence in other aspects. UE 115 may be able to deduce whether correspondence exists at base station 105a by mapping DL beams to RACH resources. One example is that if the RACH resources and the DL beams are configured using TDD, then this could indicate that base station 105a might have correspondence.
“Base station 105-a might include the indications of correspondence in a master data block (MIB), or a system information blocks (SIB), transmitted to UE 115.a. The base station might transmit the MIB via a physical broadcast channel (PBCH) and the SIB may be transmitted over an extended PBCH. The indication could be based on a preamble. One preamble may indicate no correspondence. A second preamble may indicate partial correspondence. A third preamble may indicate full correspondence. UE 115a can determine whether there is complete correspondence, partial correspondence or none. If UE 115a finds that there is no correspondence, UE 115a can select a UL beam to communicate with base station 105 -a that is different than the DL beam used at base station 105 -a.
“Also, or alternatively, UE 115a at 205 may transmit information about correspondence associated with UL beams on the UE side. UE 115 may, for example, transmit a nature and type of correspondence between one or two receive DL synchronization beacons at UE and one (or more) transmit uplink beams (UL) at UE. This could include the indication of correspondence via RACH messages (e.g. RACH msg 1, RACH msg 3, or over a physical control channel (PUCCH), or a physical downlink shared channel (PUSCH). Base station 105 may be able to receive correspondence from the UE side. Based on this indication, base station 105 may map beams used for transmitting channel state information reference signal (CSI-RSs), to beams used for transmitting sounding reference signal (SRSs) or vice-versa. Base station 105-a can also determine to map beams used for DL beam training to beams utilized in UL beam training, or vice versa, based on the indication.
“At 210 base station 105 may transmit (and receive UE 115-0) a DL sync signal to UE115-a. The DL synchronization signals may be a beamformed signal that is transmitted from base station 105a using DL synchronization beam(s). The DL synchronization signals may be associated with an indicator and/or a symbol for a subframe. A transmit power condition may also be associated with the DL synchronization signals.
“Base station 105a transmits a number of DL synchronization signal during a synchronization frame in some aspects. Each DL synchronization signals may be transmitted using a symbol in the synchronization subframe. For example, DL synchronization sign 1 may be transmitted using symbol 1, while Dl synchronization symbol 2 may be transmitted using symbol 2, etc
“At 215, UE 115 -a may identify a select DL beam from the DL synchronization beams for use in communications between base station 105 -a and UE 115 -a. UE 115 may identify the preferred DL beam by identifying a signal strength or quality of the DL synchronization signals (e.g. high received signal strength, low interference level). UE 115a may, in certain aspects, identify the selected DL beam using a transmit strength condition of the DL synchronization signals on the DL synchronization beams (e.g., a transmit force above a threshold).
“At 220, the UE 115 a may select a resource or RACH waveform to transmit the RACH message from base station 105 -a. The selected DL signal may determine the resource or RACH waveform. The RACH and/or resource waveforms may be associated with component carriers and/or with component carriers.
“At 225, UE 115 -a can transmit a RACH message from base station 105 -a. The RACH message can be transmitted using the RACH resource selected and/or RACH waveform. The RACH message can be transmitted for the entire duration of a random access subframe. For example, it may be transmitted at each symbol in the random access subsection. The RACH message can be transmitted for the entire duration of the corresponding random access slot, subframe or occasion. These terms can be used to describe a time period during which the gNB sweeps a portion or all of its receive beams in order to receive RACH messages. In certain aspects, UE 115 a may choose a RACH waveform to transmit the RACH message. Based on the selected beam, the RACH waveform can be chosen. It may include a RACH preamble or a cyclic shifting, among other things. In certain aspects, UE 115a may transmit the RACH message using a number of UL beams.
“At 230 base station 105a may identify the selected beam. Base station 105 may be able to identify the selected beam DL beam using the RACH waveform and/or resource used in the RACH message transmission. Base station 105 may, in certain aspects, identify the selected DLB beam by associating RACH waveform and resource with an index of the selected beam. Base station 105-a can identify the selected DL beacon in certain aspects by associating RACH waveform and resource with a symbol of a subframe for the DL synchronization signals of the selected DL beam.
Base station 105-a might identify the selected DL beam based upon the RACH waveform in the RACH message. Base station 105-a, for example, may identify the selected beam based on RACH preamble, the RACH message’s cyclic shift, and other factors.
“At 235 base station 105 -a may transmit additional messages to UE 115 -a using the selected DL beacon. The selected DL beam may be preferred in some cases. Base station 105 may also use the RACH message from UE 115 to determine a selected UL beacon for communications between UE 115 and base station 105. Base station 105-a might measure the quality of the RACH message received on a plurality UL beams, and then determine the selected UL beacon based on that measurement. The quality of RACH messages can be measured by measuring the reference signal received power (RSRP), the received signal strength indicator(RSSI), and the reference signal received quality quality (RSRQ).
“UE 115-a can measure the RSRP of a received message transmitted on a synchronization block (e.g. where a combination or more synchronization signals is transmitted in a particular direction) to determine the best signal. UE 115 -a may not be able to identify the strongest port associated to a symbol. UE 115 -a may indicate or transmit a preferred DL beam to basestation 105-a using other spreading codes (e.g. orthogonal cover code (OCCs). Base station 105a may transmit additional reference signals, such as a beam signal (BRS), mobility signal (MRS), and others. Inside symbols used to synchronize signals 205 and UE 115 may identify the best transmission port (e.g. best downlink transmission beam ID). UE 115a could therefore return the best downlink transmission beam identification by using different spreading codes.
Base station 105 may not have beam correspondence. Base station 105 can request UE 115 to transmit RACH in all symbols within the RACH slot. Base station 105 may then determine the best uplink reception beam by analyzing the quality of the received RACH signals. Base station 105 may establish an association between a transmit/receive beam channel or downlink signal and a subset RACH resources. This association may then be used to determine the downlink transmission beam, such as for sending Msg. UE 115 may choose the RACH resource subset or the RACH preamble indices subset based on downlink measurements of received signals. A preamble index can include a preamble sequence and an OCC index in these cases. OCC support is also possible. OCC indices can be used to indicate a subset or preambles in some cases.
“In certain aspects, there may not be correspondence between the DL synchronization beams at base station 105a and UL beams at UE 115a. In some cases, the selected DL beam might differ from the selected UL beam. Some aspects of the disclosure could allow partial or complete beam correspondence between the DL transmit beams and UL receive beams. Partial correspondence may allow the RACH message to be transmitted at 225 over a transmission time that has a center symbol that corresponds to either the symbol associated to the best DL synchronization beacon or the best received signal strength. Similar to the above, UE115-a can determine the RACH preamble for the RACH message transmitted at 225 using the best Dsynchronization beam. UE115-a could determine the subcarrier area used for transmission of RACH message at 215 based upon the best DL sync beam. This could be applicable to frequency division duplexing systems (FDD), where partial beam correspondence may not exist between the DL/UL. There may be a variation in the amount of partial beam correspondence from one situation to another. Some examples may show absent correspondence as a result of different channel propagation characteristics (e.g. different transmit power levels, different angles of departure and/or arrival etc
“In certain cases, correspondence might be present at base station 105a. The base station 105 may transmit different DL synchronization signal at different times and the base stations 105-a and UE 115 may simultaneously receive the RACH resources through a digital receiver subsystem. This may avoid analog beam constraints. A base station 105 may ask that the UE 115a map DL synchronization signal to RACH resources or waveforms. A RACH detector may be used to analyze each receive beam path at the base station 105.
The beam correspondence between the DL transmit beams and UL receive beams may be supported by aspects of the disclosure. If correspondence exists, the RACH message transmitted to 225 could be transmitted at a transmission time that corresponds with the best DL synchronization beacon or the symbol corresponding the best DL synchronization beacon.
“FIG. 3. This is an illustration of a system 300 that supports wireless communications and supports RACH conveyance information for various DL -UL correspondence states. System 300 could be one example of the wireless communication system 100 described in FIG. 1. System 300 could be a wireless communication system that uses mmW. System 300 could include a UE 115b and a basestation 105-b. These devices may be similar to the ones in FIGS. 1. and 2. System 300 is a general illustration of a discovery procedure in which UE 115b discovers base station 105b based upon DL synchronization signals transmitted via DL synchronization beams.
“Base station 105-b could be a mmW station that transmits beamformed transmissions to UE 115b. Base stations 105-b can transmit beamformed transmissions or directional transmissions directed towards UE 115.
“For instance, base station 105b may transmit DL synchronization signals on DL synchronization beams 305. Base station 105b may transmit DL synchronization signal (e.g. for random access) in a beamformed fashion and swept through the angular area (e.g. in azimuth or elevation). Each DL synchronization beam 305 can be transmitted in a beam sweeping operation, in different directions, to cover the area covered by base station 105b. For example, DL synchronization beacon 305a can be transmitted in a first direction. DL synchronization beacon 305b may be transmitted with a beam sweeping operation in a second direction. DL synchronization be 305b may be transmitted with a third direction. DL synchronization be 305c may be transmitted with a fourth direction. System 300 may show four DL synchro beams 305. However, it should be understood that there could be fewer or more DL sync beams 305. The DL synchronization beams 305 can be transmitted at different beam widths and at different elevation angles. In certain aspects, DL synchronization beacons 305 can be associated with a beam indicator, such as an indicator identifying the beam.
In some cases, DL synchronization beacons 305 can be transmitted at different symbol periods within a synchronization subframe. DL synchronization beacon 305a can be transmitted in a first symbol time (e.g. symbol 0), DL synchronization beacon 305b may be transmitted in a second symbol time (e.g. symbol 1), DL synchronization be 305b may be transmitted in a third symbol phase (e.g. symbol 2), DL synchronization be 305c may be transmitted within a fourth symbol interval (e.g. symbol 3). Additional DL synchroization beams 305 can be transmitted during additional symbol periods in the synchronization subframe.
“Generally, the beam sweeping operation supports basestation 105-b in determining which direction UE 115 b is located (e.g. after receiving response messages for UE 115 b). This allows transmission of RACH message 2 via base station 105 -b. The beam sweeping operation also improves communication when correspondence is not held between DL channels and UL channels. UE 115b may select the frequency area and/or waveform configuration (e.g. resource and/or RACH) to transmit the random access signal (e.g. RACH message, RACH msg1, RACH msg3, RACH msg3) based upon the index of the preferred or best DL synchronization signal from the DL synchronization beam 305. UE 115-1a may transmit the preferred or best DL beam by using an identification or index in a RACH msg1. Base station 105-a can find the appropriate UL beam during the random access period by receiving the random signal in a sweeping fashion. Base station 105b may identify the UE 115 -a selected DL beam using the resource and/or RACH wavesforms used (e.g. the frequency region and/or configuration used) that contain the RACH message (e.g. RACH msg1 and RACH msg3).
“UEs located within the coverage area 105-b can receive the DL synchronization signal on DL synchronization beams 305. The UE 115b can identify the best DL synchronization signal (e.g. strongest received signal strength, highest channel quality, etc.). ), and identify it as the selected DL beam. UE 115-b can then choose a resource or RACH waveform to transmit the RACH message based upon the selected DL beacon, such as the preferred DL beam. One example is that the RACH message resource and/or RACH waveform used to transmit the RACH message could correspond with the symbol of the selected DLB beam. Another example is that the RACH message could include an index or identification of the preferred beam.
“Although 16 DL beams are possible, this is a non-limiting example. UE 115b could use four bits to transmit the DL beam information from base station 105b. UE 115 b may have four subcarrier areas (e.g. resources) and four RACH waveforms. UE 115b can transmit four bits using one of the four RACH waveforms, and one of four subcarriers. UE 115b could choose to send the RACH message from base station 105b using a combination of the resource waveform and the RACHwaveform.
“In certain aspects, system 300 may allow UE 115 to select a combination from a RACH waveform or the resource used for its RACH messaging transmission based on one of several combinations of an index of a DL synchronization beacon or a symbol in the DL synchronization subsection. UE 115b can transmit random access signals (e.g. RACH message or RACH msg1 and RACH msg3) throughout the duration of the random acces subframe, and/or during a part of that random access subframe.
“Base station 105-b can determine the selected DL beam for UE 115 based on the frequency region and/or RACH waveform which contain the message 1 random access signal. Base station 105b can determine the best UL receiver beam by measuring the quality at different uplink receiver beams. Signal quality can be defined as RSRP, RSSI or RSRQ.
“UE 115-b could select the best DL synchronization signals and the frequency region for RACH and/or RACH waveforms based on the index the best DL synchronization signals. UE 115b may choose a DL synchronization beacon 305 that meets a transmit power condition. UE 115b may choose a RACH preamble or cyclic shift partly based on the index for a DL synchronization beacon 305.
“The absence or inconsistency of correspondence could indicate that the best DL beam beam and the best UL beam may not be the same.”
“UE 115-b can select a combination RACH and the resource used to transmit it based on a symbol in the DL synchronization underframe if base station 105 -b transmits multiple beams using multiple antenna port symbols within each symbol. The resource can be used to denote component carriers and/or component carriers.
“Even though the example is described in FIG. While the example in FIG. 3 is for transmitting RACH messages in a RACH Subframe, it can also be used to transmit a scheduling request message or beam recovery message within a RACH Subframe. UE 115 might find that the best synchronization beacon was transmitted during a particular symbol. In these cases, UE 115 could transmit a scheduling request, beam recovery message or beam tracking message in a frequency area that corresponds with the symbol. A different resource (or resource block in a RACHsubframe) may contain the frequency region. This means that a portion of a RACH Subframe’s resources may be used for RACH message transmissions. A second portion of a RACH Subframe might be used for scheduling request message transmissions. Finally, a third portion may be used for beam recovery and beam tracking message transmissions.
“UE 115b” may be able to receive an indication about the subcarrier area for a scheduling request message or beam recovery message transmission via RRC signaling. There may be eight (8) subcarrier regions in some cases. UE 115b may also be able to receive the desired cyclic shifting for the scheduling request message or the beam recovery/beam tracking message transmission via RRC signaling. UE 115b might use twelve (12) different cyclic shiftings to generate a sequence of the scheduling request message transmission, beam recovery, or beam tracking message message transmission. There may be more available cyclic shifting options for scheduling request message transmissions or beam recovery and beam tracking message transmissions than there are available cyclic shifts to transmit a RACH message transmission. This is because UE 115b may correct a timing error before transmitting the scheduling request message transmission. The transmission of the scheduling request message or the beam recovery, or beam tracking message, may be spread across two (2) symbols, which could provide additional degrees (e.g. 192 degrees in each symbol pair).
“FIGS. 4A and 4B show examples of a beam subframe mapping configuration 400 for RACH conveyance DL synchronization beam info for various DL?UL correspondence states. Configuration 400 could implement aspects of wireless communication network 100, process flow 200, and/or system 300 if FIGS. 1. through 3. In certain aspects, configuration 400 may be implemented using a base station 105 or a UE 115. Refer to FIGS. 1. through 3.
“With reference to FIG. “With reference to FIG. Base station 105 can transmit DL synchronization signal (e.g. for random access) in a beamformed fashion and swept through the angular coverage area (e.g. in azimuth or elevation). Each DL synchronization beam 405 may be transmitted in a beam sweeping operation in various directions in order to cover the area covered by base station 105. For example, DL synchronization beacon 405-a can be transmitted in a single direction. DL synchronization beacon 405-b, on the other hand, may be transmitted with a beam sweeping operation in a different direction to cover the coverage area of base station 105. In certain aspects, DL synchronization beacons 405 can be associated with a beam indicator, such as an indicator identifying the beam.
“In certain aspects, DL synchronization beacons 405 can also be transmitted during different symbol times of a synchronization -frame 410. The synchronization subframes 410 can be associated with a time feature (e.g. symbols) along the horizontal axis and a frequency feature (e.g. frequencies or tones) along the vertical. For example, DL synchronization beacon 405-a can be transmitted in a first symbol period (e.g. symbol 0), DL synchronization beacon 405b may be transmitted in a second symbol time (e.g. symbol 1), and so forth until DL synchronization be 405-h is transmitted in an eighth symbol period.
“In certain aspects, each DL synchronization signals transmitted on a DL synchronization beacon 405 may be transmitted at any frequency during the symbol. For example, DL synchronization beacon 405-a can be transmitted on frequency 0-7 during symbol 0. DL synchronization beacon 405-b could be transmitted on frequency 0-7 during symbol 1.
“Base station 105 can sweep DL synchronization beams 405, in eight directions, during eight symbols of synchronization subframe 410.”
“With reference to FIG. 4B: UEs 115 located within the coverage area 105 can receive the DL synchronization signal on DL synchronization beams 405 The UE 115 can identify the best DL synchronization signal (e.g. strongest received signal strength, highest channel quality, etc.). ), and this is the selected DL beam. FIG. 4B, the UE 115 identified the DL synchronization signal transmitted by DL synchronization beam 405-b as the selected DL beacon. As you can see, DL synchronization beacon 405-b was transmitted during symbol 2.
“UE 115 may select a resource for transmission of RACH message based upon the selected DL beam. One example is that the symbol of the selected DL bee may be used as the resource for transmitting the RACH message. UE 115 could choose the second resource 420 (e.g. frequency or tone 1) to transmit the RACH message. UE 115 could choose to use the second resource 420 in order to indicate the DL synchronization beam transmitted by the second symbol as the selected DL beam. As mentioned above, UE 115 could also choose a RACH waveform in order to transmit the RACH message.
“UE 115 might find that the best synchronization beam was transmitted during a second symbol. UE 115 could transmit a RACH message at the second frequency for all time slots (e.g. during all symbols in the RACH subframe 415). Base station 105 might find the best DL transmit beam in the used frequency region (e.g. second resource 420) from the random access signal (e.g. RACH message). Due to DL-UL power difference differences, some RACH message transmission times units might be longer than the synchronization time units in certain cases.
“Base station 105 could sweep the same eight directions in the RACH subframe 405. Base station 105 could configure one or more antenna arrays in order to receive the RACH message using the same sweeping pattern used to transmit the DL synchronization signals on the DL synchronization beams 405.
“The above example with reference to FIG. 4. may be applicable to cases where there is no correspondence at base station 105 regarding the selected DL beam. The example could also be applicable to cases where there is no correspondence between base station 105, UE 115. UE 115 might identify a way to transmit using the selected DL beacon based on a linkgain associated with transmissions from UE 115. In certain cases, UE 115 might determine its link gain based upon synchronization signals from base station 105. UE 115 can transmit the RACH message within a single RACH frame if it has sufficient link gain to meet a link budget. UE 115, however, may transmit the RACH message to multiple RACH subframes if UE 115 doesn’t have enough link gain to meet a link budget.
“The example is described in reference to FIGS. While 4A and 4B are intended for transmitting RACH messages in RACH 415, the example can also be used to transmit a scheduling request message or beam recovery message in RACH 415. UE 115 might find that the best synchronization beacon was transmitted during the second symbol. In these cases, UE 115 could transmit a scheduling request, beam recovery message or beam tracking message in a different frequency region for all times slots. The second frequency area may be located in a different resource (or block) in RACH 415. This means that a portion of RACH 415 resources may be used for RACH message transmissions. A second portion of RACH 415 resources may be used for scheduling request message transmissions. Finally, a third portion may be used for beam recovery and beam tracking message transmissions.
“FIGS. 5A and 5B show an example beam-subframe mapping configuration 500 to enable RACH conveyance DL synchronization beam data for different DL-UL correspondence states. Configuration 500 could implement aspects of wireless communication 100, process flow 200, and/or system 300. 1. through 3. In certain aspects, configuration 500 can be implemented using a base station 105 or a UE 115. Refer to FIGS. 1 through 3.
“With reference to FIG. “With reference to FIG. Base station 105 may transmit DL synchronization signal (e.g. for random access) in a beamformed fashion and swept through the angular coverage area (e.g. in azimuth or elevation). Each DL synchronization beacon 505 can be transmitted in a beam sweeping operation in a different direction to cover the area covered by base station 105. For example, DL synchronization beacon 505-a can be transmitted in a single direction. DL synchronization beacon 505-b, on the other hand, may be transmitted with a beam sweeping operation in a different direction to cover the coverage area of base station 105. In certain aspects, DL synchronization beacons 505 could be associated with a beam indicator, such as an indicator identifying which beam.
“In certain aspects, DL synchronization beacons 505 can also be transmitted during different symbol times of a synchronization frame 510. The synchronization subframe510 can be associated with a time feature (e.g. symbols) along the horizontal axis and a frequency feature (e.g. frequencies or tones) along the vertical. FIG. FIG. 5A shows base station 105 with four antenna arrays. Base station 105 can sweep four directions for each symbol. Antenna ports 0-3 could be grouped in subgroup 510 to transmit DL synchronization beacons 505a through 505d during the first symbol (e.g. symbol 0) within the synchronization subframe 510. Antenna ports 0-3 can be grouped in subgroup 515 to transmit DL synchronization beacons 505?e through 505?h during the second symbol (e.g. symbol 1) of synchronization subframe 510. Base station 105 can sweep eight directions in two symbols of synchronization subframe510.
“In certain aspects, each DL synchronization signals transmitted on a DL synchronization beacon 505 may be transmitted at any frequency during the symbol. DL synchronization beacon 505-a can be transmitted on any frequency or tone 0-7 during symbol 0. DL synchronization beacon 505-b can be transmitted on any frequency or tone 0-7 during symbol 1. The DL synchronization beacons 505 that are transmitted during a symbol might not be transmitted on overlapping frequencies in certain aspects.
“Base station 105 can sweep DL synchronization beams 505 in eight directions during eight symbols within the synchronization subframe 510.”
“With reference to FIG. 5B: UEs 115 in the coverage area of basestation 105 can receive the DL synchronization signal on DL synchronization beams 5005. The UE 115 can identify the best DL synchronization signal (e.g. strongest received signal strength, highest channel quality, etc.). ), and this is the selected DL beam. FIG. 5B shows an example. FIG. 5B shows that the UE 115 identified the DL synchronization signal received on DL synchronization beam 5005-a as the selected DL beacon. As noted, DL synchronization beacon 505-a was transmitted during symbol 1 (e.g. symbol 0).
“UE 115 may select a resource for transmission of RACH message based upon the selected DL beam. One example is that the symbol of the selected DL bee may be used as the resource for transmitting the RACH message. UE 115 could choose the first resource 520 (e.g. frequency or tone 0), as the resource to transmit the RACH message. UE 115 could choose to transmit the RACH message to the first resource 520 in order to indicate the DL synchronization beam transmitted by the first symbol.
“UE 115 might find that the best synchronization beam was transmitted in the first symbol. UE 115 could transmit a RACH message during the first frequency area for all time slots (e.g. all symbols in the RACH subframe 555). Base station 105 might determine the best UL received beam by measuring how the signal is received during different times slots (e.g. during different symbols). Base station 105 might find the best course of DL beam in certain aspects by measuring the quality of the received signal during different time slots (e.g. during different symbols).
“Base station 105 could sweep the same eight directions in the RACH subframe 515.” Base station 105 could configure one or more antenna arrays in order to receive the RACH message using the same sweeping pattern used to transmit the DL synchronization signals on the DL synchronization beams 505 during the synchronization subframe 510.
“FIGS. 6A and 6B show examples of a beam subframe mapping configuration 600 for RACH conveyance DL synchronization beam info for different DL-UL correspondence state. Configuration 600 could implement aspects of wireless communication network 100, process flow 200, and/or system 300, if FIGS. 1. through 3. Some aspects of configuration 600 can be implemented by a basestation 105 or a UE 115 in certain cases, as described with reference to FIGS. 1. through 3.
“With reference to FIG. “With reference to FIG. Base station 105 may transmit DL synchronization signal (e.g. for random access) in a beamformed fashion and swept through the angular coverage area (e.g. in azimuth or elevation). Each DL synchronization beam 605 can be transmitted in a beam sweeping operation in various directions to cover base station 105’s coverage area. DL synchronization beacon 605-a, for example, may be transmitted in a single direction. DL synchronization beacon 605-b, on the other hand, may be transmitted with a beam sweeping operation in a different direction to cover the coverage area of base station 105. In certain aspects, DL synchronization beacons 605 could be associated with a beam indicator (e.g. an indicator identifying which beam).
“In certain aspects, DL synchronization beacons 605 can also be transmitted during different symbol times of a synchronization frame 610. The synchronization subframe610 can be associated with a time feature (e.g. symbols) along the horizontal axis and a frequency feature (e.g. frequencies or tones) along the vertical. DL synchronization beacon 605-a can be transmitted in a first symbol period (e.g. symbol 0), DL synchronization beacon 605b may be transmitted in a second symbol period, e.g. symbol 1, and so on, until DL synchronization be 605-h is transmitted in an eighth symbol period.
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