Uplink scheduling in multi-cell MU-MIMO systems with ZF post-processing and diversity combining

Abstract

This paper considers the selection of users and corresponding uplink decoding in multi-user multiple-input multiple-output (MU-MIMO) multi-cell systems, applicable to future wireless networks with centralized processing at the wireless controller (WC). Two-layer decoding is proposed. First, for all active mobile stations (MSs) the spatial streams are decoupled at the pre-assigned base stations (BSs) by using a zero-forcing (ZF) type algorithm. Second, for MSs with strong signals, hard-decision decoding is performed at the BSs; while for other MSs, especially those at the edge of the cells, soft decisions from multiple BSs are passed to the WC, where maximum ratio combining (MRC) is performed. When deploying MRC, two strategies are considered to deal with the inter-cell interference (ICI). Assuming access at the WC to hard-decoded user data, or the lack of it, MRC with successive interference cancellation (SIC) and conventional MRC are investigated, respectively. Simulation results are provided to demonstrate the potential of the technique developed in terms of total system sum rate performance.