Two-step random access
A UE is provided with a dedicated preamble for use in a two-step random access procedure, as well as dedicated, contention-free PUSCH transmission resources for the PUSCH part of msgA. In one embodiment, the base station transmits a partial PUSCH msgA configuration to the UE using dedicated RRC signaling. In another embodiment, the base station transmits a resource index to the UE indicative of a dedicated PUSCH resource for a msgA transmission via dedicated RRC signaling.
1. A method implemented by a user equipment (UE) of performing two-step, contention-free random access, the method comprising:
receiving a partial Physical Uplink Shared Channel (PUSCH) resource configuration for a Message A (msgA) transmission including a dynamic part of the PUSCH resource configuration for the msgA transmission, the partial PUSCH resource configuration being less than a complete msgA PUSCH resource configuration, the dynamic part of the PUSCH resource configuration comprising a demodulation reference signal (DMRS) configuration;
transmitting, to a base station, the preamble of msgA; and
transmitting, to the base station, the PUSCH message of msgA using PUSCH resources indicated by the dynamic part of the PUSCH resource configuration.
2. The method of claim 1 , wherein the dynamic part of the PUSCH resource configuration comprises one of:
a time domain resource allocation; or
a frequency domain resource allocation.
3. The method of claim 2 , wherein the time domain resource allocation is indicated by an offset relative to one of:
a random access preamble configuration; or
a contention based random access configuration.
4. The method of claim 1 , wherein the time domain resource allocation comprises multiple PUSCH occasions.
5. The method of claim 1 , wherein the dynamic part of the PUSCH resource configuration comprises a modulation and coding scheme (MCS) configuration.
6. A method implemented by a base station of supporting two-step, contention-free random access, the method comprising:
transmitting, to a user equipment (UE), a partial Physical Uplink Shared Channel (PUSCH) resource configuration for a Message A (msgA) transmission including a dynamic part of the PUSCH resource configuration for the msgA transmission, the partial PUSCH resource configuration being less than a complete msgA PUSCH resource configuration, the dynamic part of the PUSCH resource configuration comprising a demodulation reference signal (DMRS) configuration;
receiving, from the UE, the preamble of msgA; and
receiving, from the UE, the PUSCH message of msgA using PUSCH resources indicated by the dynamic part of the PUSCH resource configuration.
7. The method of claim 6 , wherein the dynamic part of the PUSCH resource configuration comprises one of:
a time domain resource allocation; or
a frequency domain resource allocation.
8. The method of claim 7 , wherein the time domain resource allocation is indicated by an offset relative to a random access preamble configuration.
9. The method of claim 6 , wherein the time domain resource allocation comprises multiple PUSCH occasions.
10. The method of claim 7 , wherein the frequency domain resource allocation is indicated by an offset relative to a random access preamble configuration.
11. A user equipment (UE) configured to perform two- step, contention-free random access, the UE comprising:
communication circuitry configured for communication with a base station over a wireless communication channel; and
processing circuitry configured to, in conjunction with the communication circuitry:
receive a partial Physical Uplink Shared Channel (PUSCH) resource configuration for a Message A (msgA) transmission a dynamic part of the PUSCH resource configuration for the msgA transmission, the partial PUSCH resource configuration being less than a complete msgA PUSCH resource configuration, the dynamic part of the PUSCH resource configuration comprising a demodulation reference signal (DMRS) configuration;
transmit, to a base station, the preamble of msgA; and
transmit, to the base station, the PUSCH message of msgA using PUSCH resources indicated by the dynamic part of the PUSCH resource configuration.
12. The UE according to claim 11 , wherein the dynamic part of the PUSCH resource configuration comprises one of:
a time domain resource allocation; or
a frequency domain resource allocation.
13. A base station configured to support two-step, contention-free random access, the base station comprising:
communication circuitry configured for communication with a user equipment (UE) over a wireless communication channel; and
processing circuitry configured to, in conjunction with the communication circuitry:
transmit, to a user equipment (UE) a partial Physical Uplink Shared Channel (PUSCH) resource configuration for a Message A (msgA) transmission including a dynamic part of the PUSCH resource configuration for the msgA transmission, the partial PUSCH resource configuration being less than a complete msgA PUSCH resource configuration, the dynamic part of the PUSCH resource configuration comprising a demodulation reference signal (DMRS) configuration;
receive, from the UE, the preamble of msgA; and
receive, from the UE, the PUSCH message of msgA according to the PUSCH resource configuration.
14. The base station according to claim 13 , wherein the dynamic part of the PUSCH resource configuration comprises one of:
a time domain resource allocation; or
a frequency domain resource allocation.