Impact of closed-loop power control on SDMA/TDMA system performance

Power control is an important system requirement in SDMA (space division multiple access) to compensate for inequality of signal quality among near-end and far-end terminals. This paper presents a closed-loop power control scheme in an SDMA system to achieve the optimal power allocation and beam pattern for both uplink and downlink in the entire network. The performance of the proposed scheme is evaluated by computer simulation in terms of blocking rate and forced termination rate of a TDD-SDMA/TDMA system in a multi-cell wireless system, and it is also compared with an open-loop power control scheme. The numerical results show that the system with the closed-loop power control has significantly better performance than that with the open-loop power control. Our investigation indicates the closed-loop power control scheme has a large impact on SDMA/TDMA system performance, where the remarkable improvement in system capacity can be achieved.