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EP-4740669-A1 - COMMUNICATION APPARATUSES AND COMMUNICATION METHODS FOR RESOURCE ASSIGNMENT FOR MULTI-PHYSICAL RANDOM ACCESS CHANNEL TRANSMISSIONS

EP4740669A1EP 4740669 A1EP4740669 A1EP 4740669A1EP-4740669-A1

Abstract

The present disclosure provides communication apparatuses and communication methods for resource assignment for multi-physical Random Access Channel (multi-PRACH) transmissions. The communication apparatuses include a communication apparatus comprising: circuitry, which in operation, determines a Random Access Channel Occasion (RO) group based on a number of physical Random Access Channel (PRACH) transmissions in a multiple PRACH transmission, and determines a preamble to be used for the RO group based on a mapping between one or more preambles and one or more RO groups, the RO group comprising one or more ROs; and a transmitter, which in operation, transmits the preamble.

Inventors

  • TRAN, Xuan Tuong
  • SUZUKI, HIDETOSHI
  • OGAWA, YOSHIHIKO
  • SIM, HONG CHENG MICHAEL
  • KANG, YANG

Assignees

  • Panasonic Intellectual Property Corporation of America

Dates

Publication Date
20260513
Application Date
20240430

Claims (15)

  1. 1 . A communication apparatus comprising: circuitry, which in operation, determines a Random Access Channel Occasion (RO) group based on a number of physical Random Access Channel (PRACH) transmissions in a multiple PRACH transmission, and determines a preamble to be used for the RO group based on a mapping between one or more preambles and one or more RO groups, the RO group comprising one or more ROs; and a transmitter, which in operation, transmits the preamble.
  2. 2. The communication apparatus of claim 1 , wherein the circuitry is configured to determine the one or more RO groups and the one or more preambles based on a number of synchronization signal blocks (SSBs) and based on an index associated with one or more multiple PRACH transmissions, each of the one or more RO groups being associated with a synchronization signal block (SSB) index of the SSBs.
  3. 3. The communication apparatus of claim 1 , wherein the mapping is applicable for a duration of time, the duration of time being a set of consecutive OFDM symbols, slots, sub-frames, frames, synchronization signal block (SSB) to Random Access Channel Occasions (SSB-to-RO) association periods, or SSB-to-RO association pattern period, and the transmitter transmits the preamble in the RO group within the duration of time.
  4. 4. The communication apparatus of claim 1 , wherein the RO group is determined from the one or more RO groups based on a synchronization signal block (SSB) index of a number of SSBs.
  5. 5. The communication apparatus of claim 1 , wherein one preamble of the one or more preambles is mapped to one RO group of the one or more RO groups.
  6. 6. The communication apparatus of claim 1 , wherein the one or more preambles is a first set of preambles, the mapping between the first set of preambles and the one or more RO groups is a first mapping and there is at least a second mapping between at least a second set of one or more preambles and the one or more RO groups, the at least second set of one or more preambles being the same or different from the first set of preambles, and each set of preambles is sequentially or cyclically mapped to the one or more RO groups in time domain.
  7. 7. The communication apparatus of claim 1 , wherein each of the one or more RO groups is mapped with a same preamble or a different preamble from one another.
  8. 8. The communication apparatus of claim 1 , wherein a total number of the one or more preambles in the mapping or a total number of the one or more RO groups in the mapping is different based on a number of synchronization signal blocks (SSBs) and an index associated with one or more multiple PRACH transmissions.
  9. 9. The communication apparatus of claim 6, wherein each set of the first set of preambles and the at least second set of preambles is assigned for each of one or more transmission reception points, or each of one or more cells, or each of one or more of sets of beams.
  10. 10. The communication apparatus of claim 1 , wherein the mapping is in a form of a first table indicating one or more sets of preambles to be used in time domain and a second table indicating a set of RO groups based on an index associated with one or more multiple PRACH transmissions and a number of SSBs, and the circuitry is configured to determine the RO group and the preamble based on the first and second tables.
  11. 1 1 . The communication apparatus of claim 1 , wherein the mapping is further between the preamble, the RO group and a SSB index.
  12. 12. The communication apparatus of claim 1 , wherein the mapping is further being between the preamble, a RO group of the one or more RO groups, and a channel state information reference signal (CSI-RS) index based on a number of CSI-RSs and an index associated with one or more multiple PRACH transmissions.
  13. 13. A base station comprising: circuitry, which in operation, determines a mapping between one or more preambles and one or more Random Access Channel Occasion (RO) groups based on an index associated with one or more multiple physical Random Access Channel (PRACH) transmissions; and a transmitter, which in operation, signals the mapping to a communication apparatus.
  14. 14. The base station of claim 13, wherein the mapping is further being between a preamble of the one or more preambles, a RO group of the one or more RO groups, and (1 ) a channel state information reference signal (CSI-RS) index based on a number of CSI-RSs and the index associated with the one or more multiple PRACH transmissions, or (2) a synchronization signal block (SSB) index based on a number of SSBs and the index associated with the one or more multiple PRACH transmissions.
  15. 15. A communication method comprising: determining a Random Access Channel Occasion (RO) group based on a number of multiple physical Random Access Channel (PRACH) transmissions in a multiple PRACH transmission; determining a preamble to be used for the RO group based on a mapping between one or more preambles and one or more RO groups, the RO group comprising one or more ROs; and transmitting the preamble in the RO group.

Description

COMMUNICATION APPARATUSES AND COMMUNICATION METHODS FOR RESOURCE ASSIGNMENT FOR MULTI-PHYSICAL RANDOM ACCESS CHANNEL TRANSMISSIONS TECHNICAL FIELD [1] The present disclosure relates to communication apparatuses and communication methods. In particular, it may relate to communication apparatuses and communication methods for resource assignment for multi-physical Random Access Channel (multi-PRACH) transmissions. BACKGROUND [2] It has been identified that Physical Random Access Channel (PRACH) is a bottleneck channel in term of coverage performance in new radio (NR). Therefore, in Release 18 of relevant 3rd Generation Partnership Project (3GPP) technical specifications (TSs), for example, in RP-213579, a new working item (Wl) for new radio (NR) coverage enhancement (CovEnh) has been approved with the objective of specifying PRACH coverage enhancements under the 3GPP physical layer working group RAN1 and RAN2. The Wl further studies multiple PRACH transmissions with a same beam for a 4-step random access channel (RACH) procedure, as well as study, and if justified, specify PRACH transmissions with different beams for 4-step RACH procedure. [3] Under Release (Rel.) 15, 16 and 17 of the technical specifications (TSs), PRACH preamble resources are partitioned to differentiate multiple features for different purposes, such as preamble for a feature of contention free random access (CFRA), preambles for a feature of 2-step RACH, preambles for a feature of 4-step RACH, and preamble for a feature combination (including reduced capability (RedCap), small data transmission, slice group, and message 3 (Msg3) repetition request)). Further, for a multi-PRACH transmission, separate preambles are needed for the different numbers of PRACH transmissions such as 2 PRACH transmissions, 4 PRACH transmissions and 8 PRACH transmissions. It is appreciated that a multi-PRACH transmission can be referred to as a multiple PRACH transmission or a number of PRACH transmissions or one PRACH attempt. [4] However, it is not specified in the Rel. 15/16/17 technical specifications how PRACH preamble resource for a multi-PRACH transmission is realized. When the existing PRACH preamble partitioning as mentioned above is used to partition separate preambles for multiple values for the number of PRACH transmissions, usage of preamble resource is not fully utilized, and the number of available preambles may be not enough for other purposes, resulting in inefficient usage of preamble resources. [5] Further, synchronization signal block to RACH occasion (SSB-to-RO) mapping as currently specified in the TSs is mainly designed for single PRACH transmission and may not work well for a multi-PRACH transmission. For example, when a RO group consists of shared ROs and a SSB-to-RO association period is configured shortly, a user equipment (UE) may not be able to determine enough shared ROs for a large number of PRACH transmissions. Hence, the UE may only be able to transmit fewer PRACHs and a base station (gNB) cannot achieve a desirable combined gain of preamble detection. The shared RO means that the RO is shared between a single PRACH transmission and a multi-PRACH transmission. [6] Thus, there is a need to provide communication apparatuses and methods for resource assignment for multi-PRACH transmissions that resolve above problems. SUMMARY [7] Non-limiting and exemplary embodiments facilitate providing communication apparatuses and methods for resource assignment for multi- PRACH transmissions. [8] According to a first embodiment of the present disclosure, there is provided a communication apparatus comprising: circuitry, which in operation, determines a Random Access Channel Occasion (RO) group based on a number of physical Random Access Channel (PRACH) transmissions in a multiple PRACH transmission, and determines a preamble to be used for the RO group based on a mapping between one or more preambles and one or more RO groups, the RO group comprising one or more ROs; and a transmitter, which in operation, transmits the preamble. [9] According to a second embodiment of the present disclosure, there is provided a base station comprising: circuitry, which in operation, determines a mapping between one or more preambles and one or more Random Access Channel Occasion (RO) groups based on an index associated with one or more multiple physical Random Access Channel (PRACH) transmissions; and a transmitter, which in operation, signals the mapping to a communication apparatus. [10] According to a third embodiment of the present disclosure, there is provided a communication method comprising: determining a Random Access Channel Occasion (RO) group based on a number of multiple physical Random Access Channel (PRACH) transmissions in a multiple PRACH transmission; determining a preamble to be used for the RO group based on a mapping between one or more preambles and one or more RO groups, the RO group comprising one or more ROs; and transmitting the pream