Patent ID: 8644180
Filing Date: 2014-02-04
Classification: H04B,H04W

Abstract:
1. A method for determining attributes of communication channels of multi-user (MU)-multiple input multiple output (MIMO) users in an orthogonal frequency division multiplexing based multiple access (OFDMA) system, the method comprising: receiving from a base station, for at least one sub-band of contiguous sub-carriers, an indication of an estimate of or an upper-bound on a total number of streams that are co-scheduled by the base station on the at least one sub-band and an indication of a fraction (α) of a transmit power at the base station that is applied to streams that are scheduled for transmission to a particular user; determining one or more signal quality measures for the at least one sub-band based on at least one of the fraction or the estimate of or the upper-bound on the total number of streams that are scheduled by the base station on the at least one sub-band; determining a precoder matrix for the at least one sub-band based on at least one of the fraction or the estimate of or the upper-bound on the total number of streams that are scheduled by the base station on the at least one sub-band; and transmitting to the base station an indication of the one or more signal quality measures and an indication of the precoder matrix, wherein the signal quality measures are signal-to-interference-plus-noise ratios (SINRs), and the indication of the one or more signal quality measures is an indication of one or more channel quality indices (CQIs) that are based on the SINRs, wherein the receiving further comprises receiving an indication of a suggested or an upper-bound precoder rank, and the determining one or more signal quality measures and the recoder matrix is further based us on at least one of the fraction, the suggested or upper-bound precoder rank, or the estimate of or the upper-bound on the total number of streams that are scheduled by the base station on the at least one sub-band, and wherein at least one of the precoder matrix or the one or more SINRs are determined under the assumption that a remaining fraction of the transmit power is 1−α and is assigned to streams that are scheduled for transmission to users co-scheduled with the particular user.