QUALCOMM Incorporated
Spatial spreading in a multi-antenna communication system

Abstract:

Spatial spreading is performed in a multi-antenna system to randomize an "effective" channel observed by a receiving entity for each transmitted data symbol block. For a MIMO system, at a transmitting entity, data is processed (e.g., encoded, interleaved, and modulated) to obtain N.sub.D data symbol blocks to be transmitted in N.sub.M transmission spans, where N.sub.D.gtoreq.1 and N.sub.M>1. The N.sub.D blocks are partitioned into N.sub.M data symbol subblocks, one subblock for each transmission span. A steering matrix is selected (e.g., in a deterministic or pseudo-random manner from among a set of L steering matrices, where L>1) for each subblock. Each data symbol subblock is spatially processed with the steering matrix selected for that subblock to obtain transmit symbols, which are further processed and transmitted via N.sub.T transmit antennas in one transmission span. The N.sub.D data symbol blocks are thus spatially processed with N.sub.M steering matrices and observe an ensemble of channels.