Methods for selecting precoding vectors for multi-point MIMO (multiple-input-multiple-output) communications and related wireless terminals and radio network nodes

摘要

A wireless terminal may receive multiple-input-multiple-output (MIMO) downlink communications from a wireless communication network including a plurality of base station sector antenna arrays using a codebook of precoding vectors. MIMO downlink communications may be received from the wireless communication. When receiving the MIMO downlink communications as multi-point MIMO downlink communications from first and second base station sector antenna arrays of the plurality of base station sector antenna arrays, a precoding vector may be selected for the multi-point MIMO downlink communications from only a subset of the precoding vectors of the codebook.

主权项

1. A method of operating a wireless terminal in a wireless communication network providing multiple-input-multiple-output (MIMO) downlink communications from a plurality of base station sector antenna arrays using a codebook of precoding vectors, the method comprising:
receiving MIMO downlink communications from the wireless communication network; when receiving the MIMO downlink communications as multi-point MIMO downlink communications from first and second base station sector antenna arrays of the plurality of base station sector antenna arrays, selecting a precoding vector for the multi-point MIMO downlink communications from a subset of the precoding vectors of the codebook, wherein selecting the precoding vector for the multi-point MIMO downlink communication comprises selecting a first precoding vector from the subset of the precoding vectors of the codebook based on a first downlink channel between the wireless terminal and the first base station sector antenna array and selecting a second precoding vector from the subset of the precoding vectors of the codebook based on a second downlink channel between the wireless terminal and the second base station sector antenna array; and transmitting respective first and second identifications of the respective first and second precoding vectors selected for the multipoint MIMO downlink communication; wherein selection of precoding vectors is restricted to the subset of the precoding vectors when receiving the MIMO downlink communications as multi-point MIMO downlink communications; wherein the codebook includes Rank 1 precoding vectors supporting one layer of MIMO downlink data transmission from a base station sector antenna array and Rank 2 precoding vectors supporting two layers of downlink data transmission from a base station sector antenna array, and wherein the subset of the precoding vectors includes the Rank 1 precoding vectors and excludes the Rank 2 precoding vectors, wherein selection of precoding vectors is restricted to the Rank 1 precoding vectors when receiving the MIMO downlink communications as multi-point MIMO downlink communications.