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US-12621871-B2 - Efficient RACH behavior

US12621871B2US 12621871 B2US12621871 B2US 12621871B2US-12621871-B2

Abstract

Apparatuses, methods, and systems are disclosed for efficient RACH behavior. One method performed by a UE includes transmitting a first PRACH preamble to a base unit to start a RACH procedure and receiving a RAR (Msg2) from the base unit during a random access response window. The method includes transmitting a second PRACH preamble in response to being unable to transmit a RACH Msg3 within an indicated transmission opportunity. The UE may obtain multiple transmission opportunities for transmitting a RACH message such as RACH Msg1 or RACH Msg3 or monitor for multiple RACH Msg2 where transmission opportunity data are conveyed via a RACH Order, an RAR, or DCI for the RACH message. An apparatus or system may perform steps of the method.

Inventors

  • Alexander Johann Maria Golitschek Edler von Elbwart
  • Prateek Basu Mallick
  • Joachim Loehr
  • Hyejung Jung
  • Vijay Nangia

Assignees

  • LENOVO (SINGAPORE) PTE. LTD.

Dates

Publication Date
20260505
Application Date
20230915

Claims (20)

  1. 1 . A user equipment (UE) for wireless communication, comprising: at least one memory; and at least one processor coupled with the memory and configured to cause the UE to: transmit a first physical random-access channel (PRACH) preamble during a random access (RACH) procedure; receive a random access response message during a random access response window; determine a plurality of transmission opportunities for transmitting a RACH message 3 (Msg3) during the random access response window based on the random access response message, wherein the random access response message indicates a quantity of transmission opportunities in which the UE is allowed to transmit the RACH Msg3 and a number of copies of the RACH Msg3 the UE is to transmit; perform a clear channel assessment (CCA) prior to each of the plurality of transmission opportunities; transmit multiple copies of the RACH Msg3 based on the number of copies of the RACH Msg3 indicated by the random access response message using at least an earliest available transmission opportunity of the plurality of transmission opportunities based on the CCA; and terminate the RACH Msg3 transmission before the indicated number of copies of the RACH Msg3 are transmitted in response to receiving a RACH message 4 (Msg4) or an acknowledgement for RACH Msg3.
  2. 2 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to transmit the RACH Msg3 in at least two of the plurality of transmission opportunities based on the CCA.
  3. 3 . The UE of claim 1 , wherein the plurality of transmission opportunities corresponds to a predetermined number of RACH Msg3 transmissions, and wherein the random access response message indicates the predetermined number.
  4. 4 . The UE of claim 1 , wherein the plurality of transmission opportunities corresponds to a predetermined number of RACH Msg3 transmissions, and wherein broadcast system information indicates the predetermined number.
  5. 5 . The UE of claim 1 , wherein the plurality of transmission opportunities comprises two or more consecutive slots.
  6. 6 . The UE of claim 1 , wherein the plurality of transmission opportunities are distributed according to a slot pattern indicated in the random access response message.
  7. 7 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to restart the RACH procedure in response to being unable to transmit the RACH Msg3 during the plurality of transmission opportunities.
  8. 8 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to apply a same RACH Msg3 physical uplink shared channel (PUSCH) time and frequency allocation for the plurality of transmission opportunities.
  9. 9 . The UE of claim 1 , wherein the plurality of transmission opportunities corresponds to a predetermined number of RACH Msg3 transmissions, and wherein the at least one processor is configured to cause the UE to receive downlink control information (DCI) indicating the predetermined number.
  10. 10 . A method performed by a user equipment (UE), the method comprising: transmitting a first physical random-access channel (PRACH) preamble during a random access (RACH) procedure; receiving a random access response message during a random access response window; determining a plurality of transmission opportunities for transmitting a RACH message 3 (Msg3) during the random access response window based on the random access response message, wherein the random access response message indicates a quantity of transmission opportunities in which the UE is allowed to transmit the RACH Msg3 and a number of copies of the RACH Msg3 the UE is to transmit; performing a clear channel assessment (CCA) prior to each of the plurality of transmission opportunities; transmitting multiple copies of the RACH Msg3 based on the number of copies of the RACH Msg3 indicated by the random access response message using at least an earliest available transmission opportunity of the plurality of transmission opportunities based on the CCA; and terminating the RACH Msg3 transmission before the indicated number of copies of the RACH Msg3 are transmitted in response to receiving a RACH message 4 (Msg4) or an acknowledgement for RACH Msg3.
  11. 11 . The method of claim 10 , further comprising transmitting copies of the RACH Msg3 in at least two of the plurality of transmission opportunities based on the CCA.
  12. 12 . A base station for wireless communication, comprising: at least one memory; and at least one processor coupled with the at least one memory and configured to cause the base station to: receive, from a user equipment (UE), a first physical random-access channel (PRACH) preamble during a random access (RACH) procedure; transmit a random access response message during a random access response window, wherein the random access response message indicates a quantity of transmission opportunities in which the UE is allowed to transmit the RACH message 3 (Msg3) and a number of copies of the RACH Msg3 the UE is to transmit; allocate a plurality of transmission opportunities for transmission of the RACH Msg3 during the random access response window; receive one or more copies of the RACH Msg3 during at least one of the plurality of transmission opportunities; and transmit a RACH message 4 (Msg4) or an acknowledgement for RACH Msg3 in response to receiving the one or more copies of the RACH Msg3 and before receiving the indicated number of copies of the RACH Msg3, wherein the RACH Msg4 or the acknowledgement for RACH Msg3 indicates to terminate a transmission of additional copies of the RACH Msg3.
  13. 13 . The base station of claim 12 , wherein the at least one processor is configured to cause the base station to receive the RACH Msg3 in at least two of the plurality of transmission opportunities.
  14. 14 . The base station of claim 12 , wherein the plurality of transmission opportunities comprises two or more consecutive slots.
  15. 15 . The base station of claim 12 , wherein the plurality of transmission opportunities are distributed according to a slot pattern indicated in the random access response message.
  16. 16 . The base station of claim 12 , wherein the at least one processor is configured to cause the base station to allocate a same RACH Msg3 physical uplink shared channel (PUSCH) time and frequency allocation for the plurality of transmission opportunities.
  17. 17 . A method performed by a base station, the method comprising: receiving, from a user equipment (UE), a first physical random-access channel (PRACH) preamble during a random access (RACH) procedure; transmitting a random access response message during a random access response window, wherein the random access response message indicates a quantity of transmission opportunities in which the UE is allowed to transmit the RACH message 3 (Msg3) and a number of copies of the RACH Msg3 the UE is to transmit; indicating a plurality of transmission opportunities for transmission of the RACH Msg3 during the random access response window; receiving one or more copies of the RACH Msg3 during at least one of the plurality of transmission opportunities; and transmitting a RACH message 4 (Msg4) or an acknowledgement for RACH Msg3 in response to receiving the one or more copies of the RACH Msg3 and before receiving the indicated number of copies of the RACH Msg3, wherein the RACH Msg4 or the acknowledgement for RACH Msg3 indicates to terminate a transmission of additional copies of the RACH Msg3.
  18. 18 . The method of claim 17 , wherein the plurality of transmission opportunities comprises two or more consecutive slots.
  19. 19 . The method of claim 17 , wherein the plurality of transmission opportunities are distributed according to a slot pattern indicated in the random access response message.
  20. 20 . The method of claim 17 , further comprising allocating a same RACH Msg3 physical uplink shared channel (PUSCH) time and frequency allocation for the plurality of transmission opportunities.

Description

FIELD The subject matter disclosed herein relates generally to wireless communications and more particularly relates to an efficient RACH behavior, such as for NR-U. BACKGROUND The following abbreviations are herewith defined, at least some of which are referred to within the following description: Third Generation Partnership Project (“3GPP”), Fifth Generation Core Network (“5CG”), Fifth Generation System (“5GS”), Access and Mobility Management Function (“AMF”), Positive-Acknowledgment (“ACK”), Access Stratum (“AS”), Automatic Repeat Request (“ARQ”), Autonomous UpLink (“AUL”), Backoff Indicator (“BI”), Base Station (“BS”), Binary Phase Shift Keying (“BPSK”), Bandwidth Part (“BWP”), Cell Radio Network Temporary Identifier (“C-RNTI”), Clear Channel Assessment (“CCA”), Cyclic Prefix (“CP”), Cyclical Redundancy Check (“CRC”), Channel State Information (“CSI”), Common Search Space (“CSS”), Connection Mode (“CM”, this is a NAS state in 5GS), Contention Based Random Access (“CBRA”), Contention Free Random Access (“CFRA”), Control Plane (“CP”), Core Network (“CN”), Data Radio Bearer (“DRB”), Discrete Fourier Transform Spread (“DFTS”), Downlink Control Information (“DCI”), Downlink (“DL”), Downlink Pilot Time Slot (“DwPTS”), Discontinuous Transmission (“DTX”), Dual Connectivity (“DC”), Dual Registration mode (“DR mode”), Enhanced Clear Channel Assessment (“eCCA”), Enhanced Licensed Assisted Access (“eLAA”), Enhanced Mobile Broadband (“eMBB”), Evolved Node-B (“eNB”), Evolved Packet Core (“EPC”), Evolved Packet System (“EPS”), EPS Mobility Management (“EMM”) (this is a NAS state in EPS), Evolved UMTS Terrestrial Radio Access (“E-UTRA”), European Telecommunications Standards Institute (“ETSI”), Frame Based Equipment (“FBE”), Frequency Division Duplex (“FDD”), Frequency Division Multiple Access (“FDMA”), Frequency Division Orthogonal Cover Code (“FD-OCC”), Guard Period (“GP”), Globally Unique Temporary UE Identifier (“GUTI”), Hybrid Automatic Repeat Request (“HARQ”), Internet-of-Things (“IoT”), International Mobile Subscriber Identity (“IMSI”), Licensed Assisted Access (“LAA”), Load Based Equipment (“LBE”), Listen-Before-Talk (“LBT”), Long Term Evolution (“LTE”), Multiple Access (“MA”), Medium Access Control (“MAC”), Mobility Management Entity (“MME”), Modulation Coding Scheme (“MCS”), Machine Type Communication (“MTC”), Multiple Input Multiple Output (“MIMO”), Multi User Shared Access (“MUSA”), Narrowband (“NB”), Negative-Acknowledgment (“NACK”) or (“NAK”), New Generation Node B (“gNB”), New Generation Radio Access Network (“NG-RAN”, a RAN used for 5GS networks), New Radio (“NR”), New Radio in Unlicensed Spectrum (“NR-U”), Non-Access Stratum (“NAS”), Non-Orthogonal Multiple Access (“NOMA”), Normal Uplink (“NUL”), Operation and Maintenance System (“OAM”), Orthogonal Frequency Division Multiplexing (“OFDM”), Packet Data Unit (“PDU”)(used in connection with ‘PDU Session’), Packet Switched (“PS”, e.g., Packet Switched domain or Packet Switched service), Primary Cell (“PCell”), Physical (“PHY”), Physical Broadcast Channel (“PBCH”), Physical Downlink Control Channel (“PDCCH”), Physical Downlink Shared Channel (“PDSCH”), Pattern Division Multiple Access (“PDMA”), Physical Hybrid ARQ Indicator Channel (“PHICH”), Physical Random Access Channel (“PRACH”), Physical Resource Block (“PRB”), Physical Uplink Control Channel (“PUCCH”), Physical Uplink Shared Channel (“PUSCH”), Public Land Mobile Network (“PLMN”), Quality of Service (“QoS”), Quadrature Phase Shift Keying (“QPSK”), Radio Access Network (“RAN”), Radio Access Technology (“RAT”), Radio Resource Control (“RRC”), Random Access Procedure (“RACH”), Random Access Response (“RAR”), Radio Network Temporary Identifier (“RNTI”), Random Access Radio Network Temporary Identifier (“RA-RNTI”), Reference Signal (“RS”), Registration Area (“RA”) (similar to tacking area list used in LTE/EPC), Registration Management (“RA”, refers to NAS layer procedures and states), Remaining Minimum System Information (“RMSI”), Resource Spread Multiple Access (“RSMA”), Round Trip Time (“RTT”), Receive (“RX”), Sparse Code Multiple Access (“SCMA”), Scheduling Request (“SR”), Single Carrier (“SC”), Single Carrier Frequency Division Multiple Access (“SC-FDMA”), Secondary Cell (“SCell”), Shared Channel (“SCH”), Session Management Function (“SMF”), Signal-to-Interference-Plus-Noise Ratio (“SINR”), Single Network Slice Selection Assistance Information (“S-NSSAI”), Single Registration mode (“SR mode”), System Frame Number (“SFN”), System Information Block (“SIB”), Synchronization Signal (“SS”), Supplementary Uplink (“SUL”), Tracking Area (“TA”), Technical Specification (“TS”), Transport Block (“TB”), Transport Block Size (“TB S”), Time-Division Duplex (“TDD”), Time Division Multiplex (“TDM”), Time Division Orthogonal Cover Code (“TD-OCC”), Transmission Time Interval (“TTI”), Transmit (“TX”), Unified Data Management (“UDM”), Uplink Control Information (“UCI”), User Entity/Equipment (Mobile Terminal) (“UE”), Upli