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EP-4736562-A1 - DETERMINATION OF RACH OCCASION GROUPS

EP4736562A1EP 4736562 A1EP4736562 A1EP 4736562A1EP-4736562-A1

Abstract

Various aspects of the present disclosure relate to determination of RACH occasion (RO) groups. In an aspect, a user equipment determines a set of RO groups from a plurality of ROs in at least one synchronization signal and physical broadcast channel (PBCH) block (SSB) to RO association pattern period. The plurality of ROs are associated with a same SSB or a same set of SSBs. Each RO of the plurality of ROs is associated with a frequency index and a time index. By allocating a RO with two indexes, i.e., a frequency index and a time index, the user equipment may easily determine the RO groups that can be used for the transmission of physical random access channel (PRACH) repetitions. In this way, the RO determination rules may be enhanced.

Inventors

  • ZHANG, YUANTAO
  • MA, Ruixiang
  • YAN, Zhi

Assignees

  • Lenovo (Beijing) Limited

Dates

Publication Date
20260506
Application Date
20230630

Claims (20)

  1. A user equipment comprising: a processor; and a transceiver coupled to the processor, wherein the processor is configured to: determine a set of random access channel occasion (RO) groups from a plurality of ROs in at least one synchronization signal and physical broadcast channel (PBCH) block (SSB) to RO association pattern period, wherein the plurality of ROs are associated with a same SSB or a same set of SSBs, and wherein each RO of the plurality of ROs is associated with a frequency index and a time index.
  2. The user equipment of claim 1, wherein the frequency index of a RO is determined based on a frequency position of the RO in at least one RO that is multiplexed in a frequency domain in a same time occasion, and wherein the time index of a RO is determined based on a time position of the RO in a set of ROs that have a same frequency index.
  3. The user equipment of claim 1, wherein the processor is further configured to: determine that a set of ROs with a same frequency index in the plurality of ROs are valid or invalid, wherein the set of RO groups are determined from valid ROs in the plurality of ROs.
  4. The user equipment of claim 3, wherein: the set of ROs are valid for a physical random access channel (PRACH) repetition in the case that a following condition is met: the number of ROs in the set of ROs is the same as the number of ROs in the plurality of ROs having a lowest frequency index; or the set of ROs are invalid for the PRACH repetitions in the case that the condition is not met.
  5. The user equipment of claim 3, wherein determining that a set of ROs in the plurality of ROs are valid or invalid comprises: determining at least one RO group for a configured number of PRACH repetitions from the set of ROs, determining that the set of ROs are valid for PRACH repetitions in the case that a following condition is met: the number of RO groups in the at least one RO group is the same as the number of RO groups associated with a lowest frequency index for the configured number of PRACH repetitions; or determining that the set of ROs are invalid for the PRACH repetitions in the case that the condition is not met.
  6. The user equipment of claim 3, wherein: the set of ROs are valid for PRACH repetitions for a configured number of PRACH repetitions in the case that a following condition is met: the number of ROs in the set of ROs is equal to or larger than the configured number; or the set of ROs are invalid for the PRACH repetitions for the configured number of PRACH repetitions in the case that the condition is not met.
  7. The user equipment of claim 3, wherein: the set of ROs are valid for PRACH repetitions for a configured number of PRACH repetitions in the case that a following condition is met: a RO group can be determined from the set of ROs for the configured number of PRACH repetitions; and the set of ROs are invalid for the PRACH repetitions for the configured number of PRACH repetitions in the case that the condition is not met.
  8. The user equipment of any of claims 3-7, wherein: the frequency index associated with the set of ROs is an invalid frequency index for PRACH repetitions in the case that a following condition is met: the set of ROs are invalid for PRACH repetitions; or the frequency index associated with the set of ROs is a valid frequency index for the PRACH repetitions in the case that the condition is not met.
  9. The user equipment of any of claims 1-8, wherein the number of at least one SSB to RO association pattern periods is determined such that the number is a minimum integer fulfilling one of the following: at least one RO group of a lowest frequency index in the at least one SSB to RO association pattern periods can be determined for a maximum configured number of PRACH repetitions; at least one RO group of any valid frequency index in the at least one SSB to RO association pattern periods can be determined for a maximum configured number of PRACH repetitions; at least one RO group of a lowest frequency index in the at least one SSB to RO association pattern periods can be determined for each configured number of PRACH repetitions; or at least one RO group of any valid frequency index in the at least one SSB to RO association pattern periods can be determined for each configured number of PRACH repetitions.
  10. The user equipment of claim 1, wherein RO groups among the set of RO groups are indexed by: indexing RO groups in a first subset of RO groups among the set of RO groups with a lowest frequency index; and indexing RO groups in a second subset of RO groups among the set of RO groups with a second lowest frequency index after the indexing of the RO groups in the first subset of RO groups is completed.
  11. The user equipment of claim 1, wherein ROs in a RO group in the set of RO groups are associated with the same frequency index.
  12. The user equipment of claim 1, wherein ROs in a RO group in the set of RO groups are determined at least based on a configured frequency index offset.
  13. The user equipment of claim 1, wherein the set of RO groups are determined for a configured number of PRACH repetitions.
  14. The user equipment of claim 13, wherein the set of RO groups are determined based on at least one set of ROs, wherein a set of ROs among the at least one set of ROs are determined based on a maximum configured number for PRACH repetitions and the number of ROs, among the plurality of ROs, with a same valid frequency index.
  15. The user equipment of claim 14, wherein: in the case that the configured number is a first configured number, the set of ROs comprise a first set of ROs; and in the case that the configured number is a second configured number, the set of ROs comprise a second set of ROs which are the same as the first set of ROs.
  16. The user equipment of claim 13, wherein the set of RO groups are determined based on at least one set of ROs, wherein a set of ROs among the at least one set of ROs are determined based on the configured number and the number of ROs, among the plurality of ROs, with a same valid frequency index.
  17. The user equipment of claim 16, wherein: in the case that the configured number is a first configured number, the set of ROs comprise a first set of ROs; and in the case that the configured number is a second configured number, the set of ROs comprise a second set of ROs different from the first set of ROs.
  18. A base station comprising: a processor; and a transceiver coupled to the processor, wherein the processor is configured to: determine a set of random access channel occasion (RO) groups from a plurality of ROs in at least one synchronization signal and physical broadcast channel (PBCH) block (SSB) to RO association pattern period, wherein the plurality of ROs are associated with a same SSB or a same set of SSBs, and wherein each RO of the plurality of ROs is associated with a frequency index and a time index.
  19. A method performed by a user equipment, the method comprising: determining a set of random access channel occasion (RO) groups from a plurality of ROs in at least one synchronization signal and physical broadcast channel (PBCH) block (SSB) to RO association pattern period, wherein the plurality of ROs are associated with a same SSB or a same set of SSBs, and wherein each RO of the plurality of ROs is associated with a frequency index and a time index.
  20. A method performed by a base station, the method comprising: determining a set of random access channel occasion (RO) groups from a plurality of ROs in at least one synchronization signal and physical broadcast channel (PBCH) block (SSB) to RO association pattern period, wherein the plurality of ROs are associated with a same SSB or a same set of SSBs, and wherein each RO of the plurality of ROs is associated with a frequency index and a time index.

Description

DETERMINATION OF RACH OCCASION GROUPS TECHNICAL FIELD The present disclosure relates to wireless communications, and more specifically to determination of random access channel occasion (RO) groups. BACKGROUND A wireless communications system may include one or multiple network communication devices, such as base stations, which may be otherwise known as an eNodeB (eNB) , a next-generation NodeB (gNB) , or other suitable terminology. Each network communication devices, such as a base station may support wireless communications for one or multiple user communication devices, which may be otherwise known as user equipment (UE) , or other suitable terminology. The wireless communications system may support wireless communications with one or multiple user communication devices by utilizing resources of the wireless communication system (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers) . Additionally, the wireless communications system may support wireless communications across various radio access technologies including third generation (3G) radio access technology, fourth generation (4G) radio access technology, fifth generation (5G) radio access technology, among other suitable radio access technologies beyond 5G (e.g., sixth generation (6G) ) . In 5G new radio (NR) systems, the random-access procedure is utilized for various purposes. For example, the random-access procedure may be utilized by a UE in initial access to find a cell to camp on; or utilized by a radio resource control (RRC) IDLE/INACTIVE UE to switch to a RRC Connected mode to start data transmission/reception; or utilized by a RRC Connected UE to re-establish the lost uplink (UL) synchronization, etc. Enhancements on the random-access procedure are still needed. SUMMARY The present disclosure relates to methods, apparatuses, and systems that support determining RO groups. In a first aspect of the solution, a user equipment determines a set of RO groups from a plurality of ROs in at least one synchronization signal and physical broadcast channel (PBCH) block (SSB) to RO association pattern period. The plurality of ROs are associated with a same SSB or a same set of SSBs. Each RO of the plurality of ROs is associated with a frequency index and a time index. By allocating a RO with two indexes, i.e., a frequency index and a time index, the user equipment may easily determine the RO groups that can be used for the transmission of physical random access channel (PRACH) repetitions. In this way, the RO determination rules may be enhanced. In some implementations of the method and apparatuses described herein, the frequency index of a RO may be determined based on a frequency position of the RO in at least one RO that is multiplexed in a frequency domain in a same time occasion. The time index of a RO may be determined based on a time position of the RO in a set of ROs that have a same frequency index. Some implementations of the method and apparatuses described herein may further include determining that a set of ROs with a same frequency index in the plurality of ROs are valid or invalid. The set of RO groups may be determined from valid ROs in the plurality of ROs. In some implementations of the method and apparatuses described herein, the set of ROs may be valid for a physical random access channel (PRACH) repetition in the case that a following condition is met: the number of ROs in the set of ROs is the same as the number of ROs in the plurality of ROs having a lowest frequency index. The set of ROs may be invalid for the PRACH repetitions in the case that the condition is not met. In some implementations of the method and apparatuses described herein, determining that a set of ROs in the plurality of ROs are valid or invalid may comprise: determining at least one RO group for a configured number of PRACH repetitions from the set of ROs; determining that the set of ROs are valid for PRACH repetitions in the case that a following condition is met: the number of RO groups in the at least one RO group is the same as the number of RO groups associated with a lowest frequency index for the configured number of PRACH repetitions; or determining that the set of ROs are invalid for the PRACH repetitions in the case that the condition is not met. In some implementations of the method and apparatuses described herein, the set of ROs may be valid for PRACH repetitions for a configured number of PRACH repetitions in the case that a following condition is met: the number of ROs in the set of ROs is equal to or larger than the configured number. The set of ROs may be invalid for the PRACH repetitions for the configured number of PRACH repetitions in the case that the condition is not met. In some implementations of the method and apparatuses described herein, the set of ROs may be valid for PRACH repetitions for a configured number of PRACH repetitions in the case that a followi