Beam indication for IAB
An apparatus and system for beam indication in an integrated access backhaul (IAB) are described. A parent IAB distributed unit (DU) (IAB-DU) provides abeam restriction for restricting beams that a Mobile-Termination (MT) of a child IAB (IAB-MT) are not to use, an early physical downlink shared channel (PDSCH) beam indication or physical uplink shared channel (PUSCH) beam indication, or an explicit beam indication for transmission of an IAB-MT-specific PDSCH or PUSCH by an IAB-DU collocated with the IAB-MT. Radio resource control (RRC) signaling, a Medium Access Control (MAC) control element (CE), or downlink control information (DCI) contains the beam information.
1 . An apparatus for an integrated access backhaul (IAB), the apparatus comprising:
processing circuitry to configure the IAB to:
receive, from a parent IAB distributed unit (DU) (IAB-DU), a configuration comprising a beam restriction and an early physical downlink shared channel (PDSCH) beam indication and an early physical uplink shared channel (PUSCH) beam indication for transmission using Spatial Division Multiplexing (SDM) by a Mobile-Termination (MT) of the IAB (IAB-MT) of an IAB-MT-specific PDSCH and an IAB-MT-specific PUSCH, respectively, the beam restriction indicating a set of beams not to be used for the transmission, the early PDSCH and PUSCH beam indication indicating a beam to be used for the transmission;
transmit, via at least one beam other than the set of beams, at least one of: the IAB-MT-specific PDSCH to a child device or the IAB-MT-specific PUSCH to the parent IAB-DU; and
decode a radio resource control (RRC) MinSchedulingOffsetPreference-MT information element (IE) that contains a minSchedulingOffsetPreference-MT parameter, the minSchedulingOffsetPreference-MT parameter including preferred K0 and K2 parameters for each of a plurality of subcarrier spacings (SCS), the early PDSCH and PUSCH beam indication provided for power saving by enabling larger slot offsets for the preferred K0 and K2 parameters for each SCS than corresponding preferred K0 and K2 parameters for each SCS in a minSchedulingOffsetPreference-r16 parameter; and
a memory configured to store the beam restriction, early PDSCH beam indication, and early PUSCH beam indication.
2 . The apparatus of claim 1 , wherein the processing circuitry is configured to decode a RRC PDSCH-config information element IE that contains Transmission Configuration Indicator (TCI) states that indicate the set of beams not to be used.
3 . The apparatus of claim 1 , wherein the processing circuitry is configured to decode a Medium Access Control (MAC) control element (CE) from the parent IAB-DU that contains Transmission Configuration Indicator (TCI) states that indicate the set of beams not to be used.
4 . The apparatus of claim 3 , wherein the MAC CE contains a logical channel identifier (LCID) field having reserved LCIDs 35-46 that contain the TCI states.
5 . The apparatus of claim 3 , wherein a Ti field in the MAC CE is set to:
a first value to indicate that a TCI state with TCI-StateId-Restrict i is restricted, and
a second value to indicate that the TCI state with TCI-StateId-Restrict i is de-restricted.
6 . The apparatus of claim 1 , wherein the processing circuitry is configured to decode an IAB-MT-specific physical downlink control channel (PDCCH) having downlink control information (DCI) containing Transmission Configuration Indicator (TCI) states that indicate the set of beams not to be used.
7 . The apparatus of claim 6 , wherein the DCI contains a TCI-restrict field to restrict a Medium Access Control (MAC) control element (CE) restricted TCI state for the IAB-MT-specific PDSCH.
8 . The apparatus of claim 1 , wherein:
K0 is an L1 delay offset parameter between downlink control information (DCI) in a physical downlink control channel (PDCCH) and a PDSCH scheduled by the PDCCH, and
K2 is an L1 delay offset parameter between an uplink (UL) assignment in the PDCCH and a PUSCH scheduled by the PDCCH.
9 . The apparatus of claim 1 , wherein:
the processing circuitry is configured to decode a RRC PDSCH-TimeDomainResourceAllocation IE and a PUSCH-TimeDomainResourceAllocation IE,
the PDSCH-TimeDomainResourceAllocation IE includes a K0-MT parameter that indicates a K0 value for the IAB-MT,
the PUSCH-TimeDomainResourceAllocation IE includes a K2-MT parameter that indicates a K2 value for the IAB-MT,
K0 is an L1 delay offset parameter between downlink control information (DCI) in a physical downlink control channel (PDCCH) and a PDSCH scheduled by the PDCCH, and
K2 is an L1 delay offset parameter between an uplink (UL) assignment in the PDCCH and a PUSCH scheduled by the PDCCH.
10 . The apparatus of claim 1 , wherein:
the processing circuitry is configured to decode RRC maxK0-SchedulingOffset-MT and maxK2-SchedulingOffset-MT parameters for the IAB-MT,
the maxK0-SchedulingOffset-MT and maxK2-SchedulingOffset-MT parameters providing maximum K0 and K2 values for the IAB-MT,
K0 is an L1 delay offset parameter between downlink control information (DCI) in a physical downlink control channel (PDCCH) and a PDSCH scheduled by the PDCCH, and
K2 is an L1 delay offset parameter between an uplink (UL) assignment in the PDCCH and a PUSCH scheduled by the PDCCH.
11 . The apparatus of claim 1 , wherein the processing circuitry is configured to decode an explicit beam indication to a collocated IAB-DU collocated with the IAB-MT to indicate a beam for the collocated IAB-DU to use in communication with a child of the collocated IAB-DU.
12 . The apparatus of claim 11 , wherein the processing circuitry is configured to decode, as the explicit beam indication, a RRC TCI-State-DU IE containing Transmission Configuration Indicator (TCI) state information specific to the collocated IAB-DU.
13 . The apparatus of claim 11 , wherein the processing circuitry is configured to decode, as the explicit beam indication, an IAB-DU-specific PDSCH Medium Access Control (MAC) control element (CE) that contains Transmission Configuration Indicator (TCI) states as the set of beams for the IAB-MT-specific PDSCH.
14 . The apparatus of claim 13 , wherein a Ti field in the IAB-DU-specific PDSCH MAC CE is set to:
a first value to indicate that a TCI state with TCI-StateId-Restrict i is activated, and
a second value to indicate that the TCI state with TCI-StateId-Restrict i is de-activated.
15 . The apparatus of claim 11 , wherein the processing circuitry is configured to decode an IAB-MT-specific physical downlink control channel (PDCCH) having downlink control information (DCI), the DCI containing a Transmission Configuration Indicator (TCI)-DU field to identify one of a plurality of candidate TCI states of an IAB-DU-specific PDSCH Medium Access Control (MAC) control element (CE) as the explicit beam indication.
16 . The apparatus of claim 15 , wherein an indicated TCI is selected from candidate TCI-DU states in a PDSCH slot of the collocated IAB-DU.
17 . An apparatus for an integrated access backhaul (IAB), the apparatus comprising:
processing circuitry to configure the IAB to:
receive, for transmission to a Mobile-Termination (MT) of a child IAB (IAB-MT), a configuration comprising a beam restriction and an early physical downlink shared channel (PDSCH) beam indication and an early physical uplink shared channel (PUSCH) beam indication for transmission by the IAB-MT of an IAB-MT-specific PDSCH and an IAB-MT-specific PUSCH, respectively, using Spatial Division Multiplexing (SDM), the beam restriction indicating beams not to be used for the transmission, the early PDSCH and PUSCH beam indication indicating a beam to be used for the transmission; and
decode a radio resource control (RRC) MinSchedulingOffsetPreference-MT information element (IE) that contains a minSchedulingOffsetPreference-MT parameter, the minSchedulingOffsetPreference-MT parameter including preferred K0 and K2 parameters for each of a plurality of subcarrier spacings (SCS), the early PDSCH and PUSCH beam indication provided for power saving by enabling larger slot offsets for the preferred K0 and K2 parameters for each SCS than corresponding preferred K0 and K2 parameters for each SCS in a minSchedulingOffsetPreference-r16 parameter; and
a memory configured to store the beam restriction, early PDSCH beam indication, and early PUSCH beam indication.
18 . The apparatus of claim 17 , wherein to indicate the beams not to be used, the processing circuitry is configured to encode, for transmission to the IAB-MT, at least one of:
RRC PDSCH-config IE that contains Transmission Configuration Indicator (TCI) state,
a Medium Access Control (MAC) control element (CE) that contains TCI states having a first value to indicate restriction of an associated beam and a second value to indicate de-restriction of the associated beam, or
an IAB-MT-specific physical downlink control channel (PDCCH) having downlink control information (DCI) containing a TCI-restrict field to restrict an associated TCI state.
19 . A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors of an integrated access backhaul (IAB), the one or more processors to configure the IAB to, when the instructions are executed:
receive, from a parent IAB distributed unit (DU) (IAB-DU), a configuration comprising a beam restriction and an early physical downlink shared channel (PDSCH) beam indication and an early physical uplink shared channel (PUSCH) beam indication for transmission using Spatial Division Multiplexing (SDM) by a Mobile-Termination (MT) of the IAB (IAB-MT) of an IAB-MT-specific PDSCH and an IAB-MT-specific PUSCH, respectively, the beam restriction indicating a set of beams not to be used for the transmission, the early PDSCH and PUSCH beam indication indicating a beam to be used for the transmission;
decode a radio resource control (RRC) MinSchedulingOffsetPreference-MT information element (IE) that contains a minSchedulingOffsetPreference-MT parameter, the minSchedulingOffsetPreference-MT parameter including preferred K0 and K2 parameters for each of a plurality of subcarrier spacings (SCS), the early PDSCH and PUSCH beam indication provided for power saving by enabling larger slot offsets for the preferred K0 and K2 parameters for each SCS than corresponding preferred K0 and K2 parameters for each SCS in a minSchedulingOffsetPreference-r16 parameter; and
transmit, via at least one beam other than the set of beams, at least one of: the IAB-MT-specific PDSCH to a child device or the IAB-MT-specific PUSCH to the parent IAB-DU.
20 . The non-transitory computer-readable storage medium of claim 19 , wherein to indicate the beams not to be used, when executed the instructions further configure the one or more processors to decode, from the parent IAB-DU, at least one of:
a RRC PDSCH-config IE that contains Transmission Configuration Indicator (TCI) state,
a Medium Access Control (MAC) control element (CE) that contains TCI states having a first value to indicate restriction of an associated beam and a second value to indicate de-restriction of the associated beam, or
an IAB-MT-specific physical downlink control channel (PDCCH) having downlink control information (DCI) containing a TCI-restrict field to restrict an associated TCI state.