Panel selection for uplink transmission in a multi-transmission-reception point (TRP) system
Apparatuses and methods are disclosed for panel selection for uplink (UL) transmission in a multi-transmission-reception point (TRP) system. A method performed by a wireless transmit/receive unit (WTRU) may include receiving, for each of a plurality of transmit/receive points (TRPs), information for measuring a first set of reference signals and spatial relation information, the spatial relation information associating each of one or more transmit beams with one or more of a second set of reference signals and with physical uplink control channel (PUCCH) resources. The method may include, for each of the plurality of TRPs, measuring a pathloss of each common reference signal among the first and second set of reference signals. The method may include selecting a transmit beam and a TRP and sending a transmission to the selected TRP. The transmit beam may be associated with an antenna panel of the WTRU.
1 . A wireless transmit receive unit (WTRU) comprising a processor and a memory, the processor and memory configured to:
receive configuration information associated with a plurality of transmit/receive points (TRPs), the configuration information comprising:
an indication of a first set of reference signals associated with pathloss measurements for a first TRP of the plurality of TRPs,
an indication of a second set of reference signals associated with pathloss measurements for a second TRP of the plurality of TRPs,
first physical uplink control channel (PUCCH) spatial relation information associated with a third set of reference signals, and
second PUCCH spatial relation information associated with a fourth set of reference signals;
determine that a first subset of reference signals are common between the first set of reference signals and the third set of reference signals;
determine that a second subset of reference signals are common between the second set of reference signals and the fourth set of reference signals;
perform measurements on the first subset of reference signals and the second subset of reference signals;
for each of the plurality of TRPs that include at least one reference signal of the first subset of reference signals or at least one reference signal of the second subset of reference signals, determine a pathloss based on the measurements on the first subset of reference signals and the second subset of reference signals;
select a TRP and an associated transmit beam based on the determined pathlosses; and
send a PUCCH transmission to the selected TRP using the selected transmit beam.
2 . The WTRU of claim 1 , wherein the first PUCCH spatial relation information is associated with the first TRP and the second PUCCH spatial relation information is associated with the second TRP.
3 . The WTRU of claim 1 , wherein the selected transmit beam is associated with an antenna panel of the WTRU.
4 . The WTRU of claim 1 , wherein the first PUCCH spatial relation information associated with the third set of reference signals corresponds to PUCCH spatial relation information for the first TRP and is associated with a first set of PUCCH resources for PUCCH transmissions to the first TRP, and the second PUCCH spatial relation information associated with the fourth set of reference signals corresponds to PUCCH spatial relation information for the second TRP and is associated with a second set of PUCCH resources for PUCCH transmissions to the second TRP.
5 . The WTRU of claim 1 , wherein the selected transmit beam corresponds to a selected antenna panel at the WTRU.
6 . The WTRU of claim 1 , wherein the TRP and associated transmit beam are associated with at least one reference signal in the first subset of reference signals that are common between the first set of reference signals and the third set of reference signals, and the TRP and associated transmit beam are selected based on the at least on reference signal having a lowest pathloss measurement of the first subset of reference signals and the second subset of reference signals.
7 . The WTRU of claim 1 , wherein the configuration information associated with the plurality of TRPs comprises a first TRP identifier associated with the first TRP and a second TRP identifier associated with the second TRP.
8 . The WTRU of claim 1 , wherein the processor and the memory are configured to use a default configuration for PUCCH transmissions to the first TRP if there are no common reference signals between the first set of reference signals and the third set of reference signals.
9 . A method comprising:
receiving configuration information associated with a plurality of transmit/receive points (TRPs), the configuration information comprising:
an indication of a first set of reference signals associated with pathloss measurements for a first TRP of the plurality of TRPs,
an indication of a second set of reference signals associated with pathloss measurements for a second TRP of the plurality of TRPs,
first physical uplink control channel (PUCCH) spatial relation information associated with a third set of reference signals, and
second PUCCH spatial relation information associated with a fourth set of reference signals;
determining that a first subset of reference signals are common between the first set of reference signals and the third set of reference signals;
determining that a second subset of reference signals are common between the second set of reference signals and the fourth set of reference signals;
performing measurements on the first subset of reference signals and the second subset of reference signals;
for each of the plurality of TRPs that include at least one reference signal of the first subset of reference signals or at least one reference signal of the second subset of reference signals, determining a pathloss based on the measurements on the first subset of reference signals and the second subset of reference signals;
selecting a TRP and an associated transmit beam based on the determined pathlosses; and
sending a PUCCH transmission to the selected TRP using the selected transmit beam.
10 . The method of claim 9 , wherein the first PUCCH spatial relation information is associated with the first TRP and the second PUCCH spatial relation information is associated with the second TRP.
11 . The method of claim 9 , wherein the selected transmit beam is associated with an antenna panel of the WTRU.
12 . The method of claim 9 , wherein the first PUCCH spatial relation information associated with the third set of reference signals corresponds to PUCCH spatial relation information for the first TRP and is associated with a first set of PUCCH resources for PUCCH transmissions to the first TRP, and the second PUCCH spatial relation information associated with the fourth set of reference signals corresponds to PUCCH spatial relation information for the second TRP and is associated with a second set of PUCCH resources for PUCCH transmissions to the second TRP.
13 . The method of claim 9 , wherein the selected transmit beam corresponds to a selected antenna panel at the WTRU.
14 . The method of claim 9 , wherein the TRP and associated transmit beam are associated with at least one reference signal in the first subset of reference signals that are common between the first set of reference signals and the third set of reference signals, and the TRP and associated transmit beam are selected based on the at least on reference signal having a lowest pathloss measurement of the first subset of reference signals and the second subset of reference signals.
15 . The method of claim 9 , wherein the configuration information associated with the plurality of TRPs comprises a first TRP identifier associated with the first TRP and a second TRP identifier associated with the second TRP.
16 . The method of claim 9 , further comprising using a default configuration for PUCCH transmissions to the first TRP if there are no common reference signals between the first set of reference signals and the third set of reference signals.