A suboptimal scheduling scheme for MIMO broadcast channels with quantized SINR

This A sub-optimal scheduling scheme for a multiuser MIMO (MU-MIMO) system is considered where the main objective is to decrease the load on the feedback. In the proposed scheduling scheme Mt transmitter selects Mt most favorable users in terms of received signal-to-noise-plus-interference-ratio (SINR) at each user. To reduce feedback load in the reverse channel, we quantize the SINR values into few bits and the quantized bits are feedback to the transmitter side instead of the real values of SINR. We consider two approaches of using the threshold in determining the quantization levels in the process. In the first approach we consider a fixed threshold for all set of users where as in the second approach an adaptive threshold technique is used in which the threshold values are determined depending on the number of users. The achievable throughput using full SINR feedback and quantized SINR feedback are compared. The variation of the achieved throughput with the number of quantization bits is also presented. The comparison between the proposed quantized SINR based scheduling scheme with the full SINR feedback scheme in terms of the feedback load is also presented. Although the proposed scheme compromises on the achieved throughput but it has a remarkable advantage in terms of reduced feedback.