Transmitting a control signal scheduling a discovery signal in sidelink
Certain aspects of the present disclosure provide techniques for determining a relay capability configuration for using a control signal to schedule a physical sidelink shared channel (PSSCH) that carries information to organize sidelink connections. The control signal allows user equipments (UEs) to organize a sidelink network absent base station configurations or vendor configurations. For example, the control signal may schedule a discovery signal (DS) associated with a sidelink synchronization signal block (S-SSB). The control signal may be referred to as DS-physical sidelink control channel (DS-PSCCH), different from a normal PSCCH. The DS-PSCCH may have distinct structure and content to allow UEs to organize sidelink networks.
1 . A method for wireless communications by a first user equipment (UE), comprising:
transmitting a sidelink synchronization signal block (S-SSB) for discovery by at least a second UE; and
transmitting a control signal associated with the S-SSB to schedule a physical sidelink shared channel (PSSCH) that conveys system information (SI) for the second UE, wherein the control signal comprises a physical sidelink control channel (PSCCH), and wherein the PSCCH occupies a fixed resource location with respect to the S-SSB.
2 . The method of claim 1 , wherein the PSSCH conveys remaining minimum system information (RMSI) as a discovery signal (DS).
3 . The method of claim 1 , wherein the PSCCH indicates that the PSSCH carries the DS via a demodulation reference signal (DMRS) pattern.
4 . The method of claim 1 , wherein the S-SSB provides information on whether the PSCCH has been transmitted with the S-SSB.
5 . The method of claim 1 , wherein a bit in a master information block (MIB) provides information on whether the PSCCH has been transmitted with the S-SSB.
6 . The method of claim 1 , wherein the PSCCH is aligned in the time domain with the S-SSB and occupies a fixed number of resource blocks (RBs) in the frequency domain.
7 . The method of claim 1 , wherein the DS is aligned in the frequency domain with the S-SSB and occupies a fixed number of symbols in the time domain.
8 . The method of claim 7 , wherein the DS occupies:
a fixed number of resource blocks (RBs) in the frequency domain; or
a remaining portion of unlicensed band that is not occupied by the S-SSB.
9 . The method of claim 1 , wherein:
the S-SSB occupies at least first time and frequency resources in a first time occasion; and
the PSCCH occupies the first time and frequency resources in a second time occasion.
10 . The method of claim 1 , wherein the S-SSB comprises a master information block (MIB) providing the fixed resource location of the PSCCH with respect to the S-SSB.
11 . The method of claim 10 , wherein the MIB indicates a predefined set of resource blocks (RBs) used for transmitting the PSCCH.
12 . The method of claim 1 , wherein the PSCCH provides frequency domain resource allocation (FDRA) when the PSSCH is aligned with the PSCCH in time, wherein the FDRA indicates a starting resource block and a length of resource blocks of the PSSCH with respect to the PSCCH's location.
13 . The method of claim 1 , wherein the PSCCH provides time domain resource allocation (TDRA) when the PSSCH is aligned with the PSCCH in frequency, wherein the TDRA indicates a starting slot and a duration of occupied slots of the PSSCH with respect to the PSCCH's location.
14 . The method of claim 1 , wherein the PSCCH provides both frequency domain resource allocation (FDRA) and time domain resource allocation (TDRA) when the PSCCH does not align with the PSSCH.
15 . The method of claim 1 , wherein the PSCCH comprises at least one of: identify information of the second UE, services provided by the second UE, destination information, or groupcast information.
16 . A method for wireless communications by a second user equipment (UE), comprising:
receiving a sidelink synchronization signal block (S-SSB) transmitted by a first UE;
receiving a control signal associated with the S-SSB to schedule a physical sidelink shared channel (PSSCH) that conveys system information (SI) for the second UE, wherein the control signal comprises a physical sidelink control channel (PSCCH), and wherein the PSCCH occupies a fixed resource location with respect to the S-SSB; and
receiving the PSSCH from the first UE according to the control signal.
17 . The method of claim 16 , wherein the PSSCH conveys remaining minimum system information (RMSI) as a discovery signal (DS).
18 . The method of claim 16 , wherein the PSCCH indicates that the PSSCH carries the DS via a demodulation reference signal (DMRS) pattern.
19 . The method of claim 16 , wherein the S-SSB provides information on whether the PSCCH has been transmitted with the S-SSB.
20 . The method of claim 16 , wherein a bit in a master information block (MIB) provides information on whether the PSCCH has been transmitted with the S-SSB.
21 . The method of claim 16 , wherein the PSCCH is aligned in the time domain with the S-SSB and occupies a fixed number of resource blocks (RBs) in the frequency domain.
22 . The method of claim 16 , wherein the DS is aligned in the frequency domain with the S-SSB and occupies a fixed number of symbols in the time domain.
23 . The method of claim 22 , wherein the DS occupies:
a fixed number of resource blocks (RBs) in the frequency domain; or
a remaining portion of unlicensed band that is not occupied by the S-SSB.
24 . An apparatus for wireless communication at a first user equipment, comprising:
at least one processor; and
memory coupled to the at least one processor, the memory including code executable by the at least one processor to cause the apparatus to:
transmit a sidelink synchronization signal block (S-SSB) for discovery by at least a second UE; and
transmit a control signal associated with the S-SSB to schedule a physical sidelink shared channel (PSSCH) that conveys system information (SI) for the second UE, wherein the control signal comprises a physical sidelink control channel (PSCCH), and wherein the PSCCH occupies a fixed resource location with respect to the S-SSB.
25 . The apparatus of claim 24 , wherein the PSSCH conveys remaining minimum system information (RMSI) as a discovery signal (DS).
26 . An apparatus for wireless communication at a second user equipment, comprising:
at least one processor; and
memory coupled to the at least one processor, the memory including code executable by the at least one processor to cause the apparatus to:
receive a sidelink synchronization signal block (S-SSB) transmitted by a first UE;
receive a control signal associated with the S-SSB to schedule a physical sidelink shared channel (PSSCH) that conveys system information (SI) for the second UE, wherein the control signal comprises a physical sidelink control channel (PSCCH), and wherein the PSCCH occupies a fixed resource location with respect to the S-SSB; and
receive the PSSCH from the first UE according to the control signal.