Adaptive Signaling and Feedback for Multi-User Multiple input Multiple output (MU-MIMO)
Embodiments recognize that Multi-User Multiple Input Multiple Output (MU-MIMO) performance can be greatly enhanced if additional parameters are provided to the User Equipment (UE) during link adaptation and/or data demodulation. Recognizing the overhead that such signaling entails, embodiments provide MU-MIMO enhancement solutions that identify and signal only those parameters that can result in a large gain improvement when known at the UE. In an embodiment, the signaling rate of information can be adapted to channel and deployment conditions. In another embodiment, different parameters, which can vary according to different time scales, are signaled at different rates to the UE.
1 . An Access Point (AP), comprising:
a memory that stores instructions; and
processor circuitry configured, by executing the instructions, to:
determine parameters of a Multi-User Multiple Input Multiple Output (MU-MIMO) data transmission;
determine an MU-MIMO parameter set for a potential member of the MU-MIMO data transmission based on the determined parameters of the MU-MIMO data transmission; and
signal the MU-MIMO parameter set to the potential member for a link adaptation phase with the potential member.
2 . The AP of claim 1 , wherein the parameters of the MU-MIMO data transmission include a total transmission rank, a per member rank constraint, or a power allocation of data streams of the MU-MIMO data transmission.
3 . The AP of claim 1 , wherein the processor circuitry is further configured to select the MU-MIMO parameter set from among a plurality of MU-MIMO parameter sets.
4 . The AP of claim 1 , wherein the MU-MIMO parameter set indicates whether an MU-MIMO specific Channel Quality Indicator (CQI) computation is to be used by the potential member during the link adaptation phase.
5 . The AP of claim 4 , wherein the MU-MIMO parameter set indicates that the MU-MIMO specific CQI computation is to be used by the potential member during the link adaptation phase, and wherein the MU-MIMO parameter set further indicates a CQI computation method for the MU-MIMO specific CQI computation.
6 . The AP of claim 1 , wherein the MU-MIMO parameter set indicates whether an MU-MIMO specific Precoding Matrix Indicator (PMI) computation is to be used by the potential member during the link adaptation phase.
7 . The AP of claim 6 , wherein the MU-MIMO parameter set indicates that the MU-MIMO specific PMI computation is to be used by the potential member during the link adaptation phase, and wherein the MU-MIMO parameter set further indicates a PMI computation method for the MU-MIMO specific PMI computation.
8 . The AP of claim 1 , wherein the MU-MIMO parameter set indicates a total transmission rank, a rank for the potential member, or a power allocation of data streams of the MU-MIMO data transmission.
9 . The AP of claim 1 , wherein the MU-MIMO parameter set indicates a precoder codebook subset restriction for Precoding Matrix Indicator (PMI) computation by the potential member during the link adaptation phase.
10 . The AP of claim 1 , wherein the processor circuitry is further configured to signal an index corresponding to the MU-MIMO parameter set to the potential member.
11 . The AP of claim 1 , wherein the processor circuitry is further configured to:
identify a member group for the MU-MIMO data transmission; and
if the potential member belongs to the identified member group, signal to the potential member, during the MU-MIMO data transmission, an antenna port associated with a reference signal or a modulation scheme of another member of the identified member group.
12 . The AP of claim 11 , wherein the processor circuitry is further configured to:
pre-configure the potential member with a plurality of dynamic indication parameter sets; and
signal to the potential member an index corresponding to a selected dynamic indication parameter set of the plurality of dynamic indication parameter sets, wherein the selected dynamic indication parameter set includes the antenna port associated with the reference signal or the modulation scheme of the other member of the identified member group.
13 . A method performed by an Access Point (AP), comprising:
determining parameters of a Multi-User Multiple Input Multiple Output (MU-MIMO) data transmission;
determining an MU-MIMO parameter set for a potential member of the MU-MIMO data transmission based on the determined parameters of the MU-MIMO data transmission; and
signaling the MU-MIMO parameter set to the potential member for a link adaptation phase with the potential member.
14 . The method of claim 13 , wherein the parameters of the MU-MIMO data transmission include a total transmission rank, a per member rank constraint, or a power allocation of data streams of the MU-MIMO data transmission.
15 . The method of claim 13 , wherein the MU-MIMO parameter set indicates:
whether an MU-MIMO specific Channel Quality Indicator (COI) computation is to be used by the potential member during the link adaptation phase;
if the MU-MIMO specific CQI computation is to be used by the potential member, a CQI computation method for the MU-MIMO specific CQI computation;
whether an MU-MIMO specific Precoding Matrix Indicator (PMI) computation is to be used by the potential member during the link adaptation phase; and
if the MU-MIMO specific PMI computation is to be used by the potential member, a PMI computation method for the MU-MIMO specific PMI computation.
16 . The method of claim 13 , wherein the MU-MIMO parameter set indicates a total transmission rank, a rank for the potential member, a power allocation of data streams of the MU-MIMO data transmission, or a precoder codebook subset restriction for Precoding Matrix Indicator (PMI) computation by the potential member during the link adaptation phase.
17 . The method of claim 13 , further comprising:
identifying a member group for the MU-MIMO data transmission; and
if the potential member belongs to the identified member group,
signaling to the potential member, during the MU-MIMO data transmission, an antenna port associated with a reference signal or a modulation scheme of another member of the identified member group.
18 . A User Equipment (UE), comprising:
a memory that stores instructions; and
processor circuitry configured, by executing the instructions, to:
receive a Multi-User Multiple Input Multiple Output (MU-MIMO) parameter set associated with a MU-MIMO data transmission;
compute a Channel Quality Indicator (CQI) and a Precoding Matrix Indicator (PMI) in accordance with the MU-MIMO parameter set; and
signal the CQI and PMI to a network entity.
19 . The UE of claim 18 , wherein the processor circuitry is further configured to:
compute the CQI in accordance with an MU-MIMO specific COI computation method indicated by the MU-MIMO parameter set.
20 . The UE of claim 18 , wherein the processor circuitry is further configured to:
compute the PMI in accordance with an MU-MIMO specific PMI computation method or a precoder codebook subset restriction indicated by the MU-MIMO parameter set.
21 . The UE of claim 18 , wherein the processor circuitry is further configured to:
receive, during the MU-MIMO data transmission, an antenna port associated with a reference signal or a modulation scheme of a member of the MU-MIMO data transmission; and
use the antenna port or the modulation scheme to estimate intra-cell interference due to the member in the MU-MIMO data transmission.