Patent Document ID: 10063300
Application ID: 15312019
Patent Status: 1

Claim One:
1. A method for computing precoder matrix indicators (PMIs) in a wireless communication system, the wireless communication system including a base station (eNB) which is operable to communicate with one or more user equipments (UEs) and a set of multiple transmit antennas associated with the eNB that are partitioned into multiple transmit antenna subsets with one of the subsets designated as a reference subset, wherein the UEs are operable to compute multiple PMIs for the respective multiple subsets and to report the multiple PMIs to the eNB for the eNB to use in precoding, the method comprising: computing a PMI for a given subset based on or using the PMI for the reference subset, wherein a channel H is a frequency response of a radio link between the transmit antennas associated with the eNB and receiver antennas associated with the UEs, partitioning an array of transmit antennas into N transmit antenna subsets causes partitioning of the channel into N subchannels, and H n is a channel estimate of the n -th antenna subset, wherein the method further involves: A) Computing a PMI p 1 , of the reference subset (n=1); B) Performing the following for each of (non-reference) antenna subsets n=2,. .. ,N: (i) Generating a composite channel matrix G n ; (ii) Generating composite precoder candidates V p ; and (iii) Finding a PMI p n , wherein A) computing the PMI p 1 , of the reference subset (n=1) is performed according to the following equation, p 1 = arg ⁢ ⁢ max p ∈ { 1 , … , N p } ⁢ { tr ⁡ ( [ H 1 ⁢ V p ] H ⁡ [ H 1 ⁢ V p ] ) } wherein (i) generating the composite channel matrix G n is performed according to the following equation, 
 G n =[H 1 H n ] wherein (ii) generating composite precoder candidates V p is performed according to the following equation, and V p = [ W p 1 W p ] , p =1,. .. ,Np and W p is a codeword of a PMI codebook wherein (iii) finding the PMI p n is performed according to the following equation, p n = arg ⁢ ⁢ max p ∈ { 1 , … , N p } ⁢ { tr ⁡ ( [ G n ⁢ V p ] H ⁡ [ G n ⁢ V p ] ) } , H denotes conjugate transpose.