Transmitter Centric Scheduling in Multi-Cell MIMO Uplink System

This paper considers the multi-user MIMO collaborative spatial multiplexing uplink scheduling scheme in multi-cell time-division duplexing system. An transmitter centric (TC) beamforming and scheduling scheme has been proposed to reduce the inter-cell interference opportunistically. Most previous works in the area of mimo beamforming and scheduling are aiming at improve the signal to interference plus noise power ratio at receiver directly. These receiver centric (RC) schemes requires interference covariance at receiver. However, in multi-user system, the uplink interference at base station (BS) is fluctuant and can´t be acquired for scheduling due to the dynamics of the scheduled user set in other cells. It makes the uplink scheduling problem challenging. Our proposed TC scheme considers the pollution which is defined as the sum power of user signal arriving at other BSs. User selects the transmit beamforming vector with highest signal to pollution plus noise ratio (SPR) and informs its home BS. To enhance the signal and suppress the pollution, a scheduling criterion is derived based on SPR metric with awareness of intra-cell interference. The proposed scheduling scheme is compared with conventional RC and single-user TC spatial multiplexing in the scenarios with various antenna configurations, BS and user numbers. The simulation result shows that our proposed TC scheme can better reduce the pollution and significantly improve the system capacity.