Patent ID: 8243582
Filing Date: 2012-08-14
Classification: H04B

Abstract:
1. A method for feeding back channel state information of downlink (DL) channels from a mobile station (MS) to one or multiple base stations (BSs) in a cell of a wireless IEEE 802.16m network for closed-loop precoding, wherein the DL channels are correlated, comprising: storing an identical codebook at the BS and each MS, wherein the codebook includes a set codewords {V}, such that the codebooks shared between the BSs and the set of MSs; determining, at a particular MS, a covariance matrix on a particular subcarrier j of a particular DL channel as where E is expected value operator, H indicates a conjugate transpose, the matrix P j is full-rank, z is inter-cell interference, and n is additive white Gaussian noise (AWGN), and wherein a long term channel covariance matrix is where H ij is a correlated channel matrix for an i th OFDM symbol and j th subcarrier; quantizing the covariance matrix R; and feeding back the quantized covariance matrix R from the MS to the BS.