Multi-Stream Beamforming And Its Application To D-STTD With Sub Group Beamforming In HSDPA Environments

Abstract

In this paper, we apply the multi-stream beamforming (MSB) concept to double space time transmit diversity (DSTTD) with sub-group beamforming (SGB). Since four transmit antennas are divided into two pairs, each pair is beamformed independently with each beamforming matrix obtained from each sub-channel matrix. Since each beamforming matrix concerns only two transmit antennas, the amount of feedback is reduced remarkably compared to that of original MSB system. We compare the single user throughput of D-STTD and D-STTD with SGB in HSDPA environments. We can note that application of MSB concept to D-STTD enhance throughput further with small amount of feedback.