A Study on the Uplink SDMA Systems: User Scheduling, Transmit Power Control, and Receive Beamforming

ABSTRACT In this paper, we investigate the user scheduling, transmit beamforming, and receive beamforming of uplink space division multiple access (SDMA) systems where multiple users are allowed to transmit their signal to a base station (BS) using the same frequency band simultaneously. The BS performs a receive beamforming using the predetermined pseudo-random pattern and select users with a specific criterion. Especially, in this paper, we propose the threshold-based transmit power control, in which a user decrease its transmit power according if its generating interference to other users’s signal is larger than a predetermined threshold. Assuming that the TDD system is used, the channel state information (CSI) can be obtained at each user from pilot signals from the BS. Simulation results show that the proposed technique significantly outperforms the existing user scheduling algorithms. 키워드 : 다중안테나, 셀룰라 네트워크, 빔포밍, 전력 제어, 사용자 스케쥴링 Key word : MIMO, cellular networks, beamforming, power control, user schedulingJournal of the Korea Institute of Information andCommunication Engineering