Patent ID: 8284855
Filing Date: 2012-10-09
Classification: H04B,H04L,H04W

Abstract:
1. A method implemented in a base station used for a downlink multi-user (MU) multi-input multi-output (MIMO) system, comprising: receiving an indication of a quantized vector from each of a plurality of user equipments; determining the precoder; precoding data streams for the plurality of user equipments; and transmitting the precoded data to the plurality of user equipments, wherein the precoded data is expressed by equation wherein the number of the data streams is equal to or greater than the number of the user equipments, and wherein determining the precoder comprises: (a) initializing initial precoder {tilde over (G)} where {circumflex over (V)} =[{circumflex over (v)} 1 , {circumflex over (v)} 2 , . . . , {circumflex over (v)} L ] T , P is average power, L is the number of the data streams, and I is an identity matrix; (b) determining k at a k th iteration; (c) determining (k+1) where H is a channel matrix of transmission channels to the plurality of user equipments, E denotes the expectation operation, D is the set of channel over which the expectation is taken, γ=diag(T 1 H 1 g 1 , T 2 H 2 g 2 , . . . T L H L g L ), g l is the l th column of the precoder G, (d) performing (b) and (c) for a specific number of iteration, where the specific number of iteration ≧0.