Joint Spatial-Frequency Opportunistic Multiuser Diversity for VBLAST OFDMA

For OFDMA system, the greedy subcarrier and bit loading can be adopted to exploit the multiuser diversity in frequency domain for the independent fading of different users and achieve higher cell throughput without considering the user fairness. Meanwhile in MIMO scenario, different UE experience independent spatial fading for different location, and thus the different antenna at the base station (BS) can be allocated to different UEs to exploit the spatial multiuser diversity gain. In this paper, the joint spatial-frequency opportunistic multiuser scheduling is proposed for VBLAST OFDMA downlink to obtain the spatial-frequency multiuser diversity and better throughput performance. As only partial CSI is available at the transmitter, the SNR of the post-detection of every transmit antennas are feedback, the total power of BS is divided into every antenna of every subcarrier uniformly. The simulation results shows that the proposed algorithm is better than that of frequency domain greedy algorithm by 20%