System and method for enhanced multi-beam operation
A system, method and apparatus for mobile communications including sidelink transmissions is provided. A user equipment (UE) receives one or more messages comprising configuration parameters of reference signals associated with a plurality of uplink beams and a first downlink beam. The UE identifies a plurality of uplink beams associated with the first downlink beam based on a measurement of the reference signals and a corresponding ranking associated with each of the plurality of uplink beams. The UE determines a first plurality of uplink beams that satisfy maximum permissible exposure (MPE) limits and that are not subject to link failure. The UE then transmits uplink data or control information using the first uplink beam with the highest ranking.
1 . A communication method for a user equipment (UE) configured to communicate with a base station, the communication method comprising:
receiving, by the UE from the base station, downlink reference signals associated with a plurality of downlink beams comprising a first downlink beam;
transmitting, by the UE to the base station, measurement information associated with at least the first downlink beam, wherein the measurement information comprises at least one identifier of the first downlink beam;
selecting, by the UE, an uplink beam associated with the first downlink beam based on a measurement of the downlink reference signals using a beam correspondence; and
transmitting, by the UE to the base station, uplink data or control information using the uplink beam.
2 . The communication method of claim 1 , wherein the reference signals comprise at least one of:
channel state information reference signals (CSI-RSs) or
synchronization signal blocks (SSBs).
3 . The communication method of claim 1 , wherein selecting the uplink beam comprises selecting a plurality of uplink beams associated with the first downlink beam based on the measurement of the reference signals, and the communication method further comprises:
identifying a corresponding ranking associated with each of the plurality of uplink beams.
4 . The communication method of claim 3 , wherein:
the plurality of uplink beams corresponds to a first plurality of downlink beams based on the beam correspondence; and
the first plurality of downlink beams is associated with downlink precoding matrix indicators (PMIs) that have highest matching with a first downlink PMI associated with the first downlink beam.
5 . The communication method of claim 4 , further comprising:
determining the downlink PMIs based on a pre-determined codebook.
6 . The communication method of claim 4 , wherein individual rankings of the plurality of uplink beams are based on a matching between a PMI associated with a downlink beam, corresponding to the uplink beam, and the first downlink PMI associated with the first downlink beam.
7 . The communication method of claim 3 , wherein maximum permissible exposure (MPE) limits associated with individual uplink beams of the plurality of uplink beams are independent from each other.
8 . The communication method of claim 7 , wherein a MPE limit of an identified uplink beam is associated with a first maximum allowed output power reduction (P-MPR) and a first maximum uplink duty cycle.
9 . The communication method of claim 8 , further comprising:
determining whether the plurality of uplink beams is subject to link failure based on whether the plurality of uplink beams satisfy the MPE limits.
10 . The communication method of claim 9 , wherein determining whether the plurality of uplink beams is subject to link failure is based on the P-MPRs.
11 . The communication method of claim 9 , wherein determining whether the plurality of uplink beams is subject to link failure is based on maximum uplink duty cycles associated with the plurality of uplink beams.
12 . The communication method of claim 3 , further comprising:
determining a first plurality of uplink beams, of the plurality of uplink beams, that satisfy maximum permissible exposure (MPE) limits and that are not subject to link failure; and
determining a first uplink beam, of the first plurality of uplink beams, that is associated with a highest corresponding ranking.
13 . The communication method of claim 12 , wherein the first uplink beam is identified while using the first downlink beam for receiving a physical downlink control channel (PDCCH).
14 . The communication method of claim 13 , wherein using the first downlink beam comprises detecting one or more first reference signals associated with the first downlink beam.
15 . The communication method of claim 12 , further comprising:
transmitting, to the base station, an indication of switching to the first uplink beam by the UE.
16 . The communication method of claim 15 , wherein transmitting the indication includes transmitting the indication based on a medium access control (MAC) control element (CE).
17 . The communication method of claim 16 , wherein transmitting the indication based on the MAC CE includes transmitting the indication via a physical uplink shared channel.
18 . The communication method of claim 16 , wherein the MAC CE is a power headroom report (PHR).
19 . The communication method of claim 18 , wherein the PHR comprises a field with a first value indicating switching to the first uplink beam by the UE or a second value of the field indicating no uplink beam switching.
20 . The communication method of claim 1 , wherein a reference signal associated with the first downlink beam is a reference signal received with a highest power.
21 . The communication method of claim 1 , further comprising:
receiving, from the base station, a MAC CE indicating a set of downlink beams, comprising the first downlink beam for receiving downlink data.
22 . The communication method of claim 21 , further comprising:
receiving, from the base station, downlink control information comprising a transmission configuration indication (TCI) state field indicating the first downlink beam as a selected downlink beam, from the set of downlink beams, for receiving a scheduled physical downlink shared channel (PDSCH).
23 . The communication method of claim 1 , further comprising:
receiving, from the base station, a MAC CE comprising a TCI state identifier indicating the first downlink beam, as a selected downlink beam, for receiving a physical downlink control channel (PDCCH).
24 . The communication method of claim 1 , further comprising:
receiving, from the base station, one or more messages comprising configuration parameters associated with the reference signals.
25 . The communication method of claim 1 , further comprising:
receiving, from the base station, a MAC CE indicating at least one of a TCI state or downlink control information comprising a field of the TCI state indicating a Quasi-Colocation (QCL) between the reference signals.
26 . The communication method of claim 25 , wherein the reference signals include at least one of SSB or CSI-RS.
27 . The communication method of claim 1 , wherein a QCL is maintained between the reference signals.
28 . The communication method of claim 1 , further comprising:
receiving, by the UE from the base station, transmission configuration information (TCI) state configuration information for configuring quasi co-location (QCL) relationship between one or more of the downlink reference signals and one or more demodulation reference signal (DM-RS) ports of one or more downlink channels.
29 . A user equipment (UE) configured to communicate with a base station, the UE comprising:
reception circuitry configured to receive, from the base station, downlink reference signals associated with a plurality of downlink beams comprising a first downlink beam;
transmission circuitry configured to transmit, to the base station, measurement information associated with at least the first downlink beam, wherein the measurement information comprises at least one identifier of the first downlink beam; and
selection circuitry configured to select an uplink beam associated with the first downlink beam based on a measurement of the downlink reference signals using a beam correspondence, wherein,
the transmission circuitry is further configured to transmit uplink data or control information using the uplink beam.
30 . The UE of claim 29 , wherein the reception circuitry is further configured to receive, from the base station, transmission configuration information (TCI) state configuration information for configuring quasi co-location (QCL) relationship between one or more of the downlink reference signals and one or more demodulation reference signal (DM-RS) ports of one or more downlink channels.
31 . A communication method for a base station configured to communicate with a user equipment (UE), the communication method comprising:
transmitting, by the base station to the UE, downlink reference signals associated with a plurality of downlink beams comprising a first downlink beam;
receiving, by the base station from the UE, measurement information associated with at least the first downlink beam, wherein the measurement information comprises at least one identifier of the first downlink beam; and
receiving, by the base station from the UE, uplink data or control information transmitted by using an uplink beam, wherein the uplink beam is associated with the first downlink beam and is selected by the UE based on a measurement of the downlink reference signals using a beam correspondence.
32 . The communication method of claim 31 , further comprising:
transmitting, by the base station to the UE, transmission configuration information (TCI) state configuration information for configuring quasi co-location (QCL) relationship between one or more of the downlink reference signals and one or more demodulation reference signal (DM-RS) ports of one or more downlink channels.
33 . A base station configured to communicate with a user equipment (UE), the base station comprising:
transmission circuitry configured to transmit, to the UE, downlink reference signals associated with a plurality of downlink beams comprising a first downlink beam; and
reception circuitry configured to receive, from the UE, measurement information associated with at least the first downlink beam, wherein the measurement information comprises at least one identifier of the first downlink beam, wherein
the reception circuitry is further configured to receive, from the UE, uplink data or control information transmitted by using an uplink beam, wherein the uplink beam is associated with the first downlink beam and is selected by the UE based on a measurement of the downlink reference signals using a beam correspondence.
34 . The base station of claim 33 , wherein the transmission circuitry is further configured to transmit, to the UE, transmission configuration information (TCI) state configuration information for configuring quasi co-location (QCL) relationship between one or more of the downlink reference signals and one or more demodulation reference signal (DM-RS) ports of one or more downlink channels.