Method and apparatus for random access procedure
Embodiments of the present disclosure provide methods and apparatuses for random access procedure. A method at a user equipment (UE) comprises selecting a synchronization signal and physical broadcast channel block (SSB) with a signal measured metric satisfying a criterion. The method further comprises transmitting a first message including a random access channel (RACH) preamble on a RACH occasion and data on an uplink shared channel (USCH) to a base station. The RACH preamble and the RACH occasion are selected based on a mapping of the SSB to the RACH preamble and the RACH occasion. The method further comprises receiving a second message from the base station as a response to the first message.
1. A method at a user equipment (UE), comprising:
selecting a synchronization signal and physical broadcast channel block (SSB) with a signal measured metric satisfying a criterion;
transmitting a first message including a random access channel (RACH) preamble on a RACH occasion and data on an uplink shared channel (USCH) to a base station, wherein the RACH preamble and the RACH occasion are selected based on a mapping of the SSB to the RACH preamble and the RACH occasion; and
receiving a second message from the base station as a response to the first message,
wherein the second message is a multiplexed response comprising a respective response to the first message of the UE, and another response to at least one other UE,
wherein a Radio Network Temporary Identifier (RNTI) for the second message is one of:
a common RNTI of the UE and the at least one other UE;
a UE-specific RNTI with a higher priority between the UE and the at least one other UE;
a UE-specific RNTI randomly selected from UE specific RNTI of the UE and at least one other's UE's UE specific RNTI; and
a UE-specific RNTI determined based on a measurement on uplink signals from the UE and the at least one other UE or a measurement by the UE and the at least one other UE on downlink signals.
2. The method according to claim 1 , wherein the data comprises information indicating at least one SSB with the signal measured metric satisfying the criterion.
3. The method according to claim 2 , wherein the at least one SSB indicated by the first message includes one or more SSBs that are associated with the RACH occasion.
4. The method according to claim 2 , wherein the at least one SSB indicated by the first message includes the SSBs in a set of SSBs with the signal measured metric satisfying the criterion except the SSB indicated by the RACH preamble and the RACH occasion.
5. The method according to claim 1 , wherein the at least one SSB is indicated by a list sorted by the signal measured metric or a bitmap.
6. The method according to claim 1 , wherein the RACH is a physical random access channel (PRACH), the USCH is a physical uplink shared channel (PUSCH) and the signal measured metric is reference signal received power (RSRP), or reference signal received quality (RSRQ), or signal-to-interference-plus-noise ratio (SINR) measured based on a downlink signal.
7. The method according to claim 1 , wherein the criterion is that the signal measured metric larger than or no less than a threshold.
8. The method according to claim 1 , wherein the UE and the at least one other UE:
have a same determined MCS are multiplexed in the second message;
have a certain common SSB with a signal measured metric satisfying the criterion are multiplexed in the second message;
transmit RACH preambles mapped to a same SSB are multiplexed in the second message; and/or
have a same downlink preferred beam are multiplexed in the second message.
9. The method according to claim 1 , wherein a beam for the second message is one of:
a common downlink beam of the UE and the at least one other UE;
a beam covering at least one of the UE's preferred beam and the at least one other UE's preferred beam;
a preferred beam of a UE with a higher priority between the UE and the at least one other UE; and
a beam randomly selected from the UE's preferred beam and the at least one other UE's preferred beam.
10. The method according to claim 1 , wherein a radio network temporary identifier (RNTI) for the second message is one of:
a common RNTI of the UE and the at least one other UE;
a UE-specific RNTI with a higher priority between the UE and the at least one other UE;
a UE-specific RNTI randomly selected from the UE's UE specific RNTI and the at least one other UE's UE specific RNTI; and
a UE-specific RNTI determined based on a measurement on uplink signals from the UE and the at least one other UE or a measurement by the UE and the at least one other UE on downlink signals.
11. The method according to claim 10 , wherein
the common RNTI is computed based on a same RACH occasion when the at least one other UE and the UE having the first message transmitted on the same RACH occasion, or
the common RNTI is a group RNTI defined for the UE and the at least one other UE; or
the common RNTI is indicated in respective first message from the UE and the at least one other UE.
12. A method at a base station, comprising:
receiving a first message including a random access channel (RACH) preamble on a RACH occasion and data on an uplink shared channel (USCH) from a user equipment (UE), wherein the RACH preamble or the RACH occasion indicates an SSB selected by the UE based on a mapping of the SSB to the RACH preamble and the RACH occasion; wherein the selected SSB has a signal measured metric satisfying a criterion; and
transmitting a second message as a response to the first message to the UE, wherein the second message is a multiplexed response comprising a respective response to the first message of the UE, and another response to at least one other UE,
wherein a Radio Network Temporary Identifier (RNTI) for the second message is one of:
a common RNTI of the UE and the at least one other UE;
a UE-specific RNTI with a higher priority between the UE and the at least one other UE;
a UE-specific RNTI randomly selected from UE specific RNTI of the UE and at least one other's UE's UE specific RNTI; and
a UE-specific RNTI determined based on a measurement on uplink signals from the UE and the at least one other UE or a measurement by the UE and the at least one other UE on downlink signals.
13. The method according to claim 12 , wherein the data comprises information indicating at least one SSB with the signal measured metric satisfying the criterion, the method further comprises: selecting a downlink beam for transmitting the second message to the UE based on the indication in the data.
14. A method at a base station, comprising:
receiving a first message including a random access channel (RACH) preamble on a RACH occasion and data on an uplink shared channel (USCH) from a user equipment (UE); and
transmitting a second message as respective response to respective first message of the UE, wherein the second message is a multiplexed response comprising the respective response to the first message of the UE, and another response to at least one other UE,
wherein a radio network temporary identifier (RNTI) for the second message is one of
a common RNTI of the UE and the at least one other UE;
a UE specific RNTI of a UE with a higher priority between the UE and the at least one other UE;
a UE specific RNTI randomly selected from the UE's UE specific RNTI and the at least one other UE's UE specific RNTI; and
a UE specific RNTI determined based on a measurement on uplink signals from the UE and the at least one other UE or a measurement by the UE and the at least one other UE on downlink signals.
15. The method according to claim 14 , wherein
the common RNTI is computed based on a same RACH occasion when the at least one other UE and the UE having the first message transmitted on the same RACH occasion, or
the common RNTI is a group RNTI defined for the UE and the at least one other UE; or
the common RNTI is indicated in respective first message from the UE and the at least one other UE.
16. An apparatus at a user equipment (UE), comprising:
a processor; and
a memory coupled to the processor, said memory containing instructions executable by said processor, whereby said apparatus is operative to:
select a synchronization signal and physical broadcast channel block (SSB) with a signal measured metric satisfying a criterion;
transmit a first message including a random access channel (RACH) preamble on a RACH occasion and data on an uplink shared channel (USCH) to a base station, wherein the RACH preamble and the RACH occasion are selected based on a mapping of the SSB to the RACH preamble and the RACH occasion; and
receive a second message as a response to the first message from the base station, wherein the second message is a multiplexed response comprising a respective response to the first message of the UE, and another response to at least one other UE,
wherein a Radio Network Temporary Identifier (RNTI) for the second message is one of:
a common RNTI of the UE and the at least one other UE;
a UE-specific RNTI with a higher priority between the UE and the at least one other UE;
a UE-specific RNTI randomly selected from UE specific RNTI of the UE and at least one other's UE's UE specific RNTI; and
a UE-specific RNTI determined based on a measurement on uplink signals from the UE and the at least one other UE or a measurement by the UE and the at least one other UE on downlink signals.
17. An apparatus at a base station, comprising:
a processor; and
a memory coupled to the processor, said memory containing instructions executable by said processor, whereby said apparatus is operative to:
receive a first message including a random access channel (RACH) preamble on a RACH occasion and data on an uplink shared channel (USCH) from a user equipment (UE), wherein the RACH preamble or the RACH occasion indicates an SSB selected by the UE based on a mapping of the SSB to the RACH preamble and the RACH occasion;
wherein the selected SSB has a signal measured metric satisfying a criterion; and
transmit a second message as a response to the first message to the UE, wherein the second message is a multiplexed response comprising a respective response to the first message of the UE, and another response to at least one other UE,
wherein a Radio Network Temporary Identifier (RNTI) for the second message is one of:
a common RNTI of the UE and the at least one other UE;
a UE-specific RNTI with a higher priority between the UE and the at least one other UE;
a UE-specific RNTI randomly selected from UE specific RNTI of the UE and at least one other's UE's UE specific RNTI; and
a UE-specific RNTI determined based on a measurement on uplink signals from the UE and the at least one other UE or a measurement by the UE and the at least one other UE on downlink signals.
18. The apparatus according to claim 17 , wherein the data comprises information indicating at least one SSB with the signal measured metric satisfying the criterion, and the apparatus is further operative to select a downlink beam for transmitting the second message to the UE based on the indication in the data.
19. An apparatus at a base station, comprising:
a processor; and
a memory coupled to the processor, said memory containing instructions executable by said processor, whereby said apparatus is operative to:
receive a first message including a random access channel (RACH) preamble on a RACH occasion and data on an uplink shared channel (USCH) from a user equipment (UE); and
transmit a second message as respective response to respective first message of the UE, wherein the second message is a multiplexed response comprising the respective response to the first message of the UE, and another response to at least one other UE,
wherein a radio network temporary identifier (RNTI) for the second message is one of
a common RNTI of the UE and the at least one other UE;
a UE specific RNTI of a UE with a higher priority between the UE and the at least one other UE;
a UE specific RNTI randomly selected from the UE's UE specific RNTI and the at least one other UE's UE specific RNTI; and
a UE specific RNTI determined based on a measurement on uplink signals from the UE and the at least one other UE or a measurement by the UE and the at least one other UE on downlink signals.