Institute of Electrical & Electronic Engineers
In this paper, MIMO extensions to the existing HSUPA system are presented and evaluated. Three candidate MIMO enhancement architectures are proposed that differ with respect to the principles of code word mapping onto the two spatial streams for rank-2 transmission. The evaluation demonstrates MIMO throughput gains relative to SIMO ranging between 30% and 40%. The MIMO architecture with independent transmission of two code words over the two spatial channels is demonstrated to be the most effective because of its ability independently to adapt the data rate on each spatial channel to the instantaneous channel conditions. The gains are realized at high RoT values, indicating isolated small cells with low UE densities as the likely deployment scenario for HSUPA MIMO.