A Near-Capacity Linear Precoder for the MIMO Broadcast Channel

Dirty-paper coding (DPC) is a well-known construction capable of achieving the ultimate capacity limit of the MIMO broadcast channel (MIMO-BC). One recently proposed DPC scheme is based on Voronoi codes, minimum mean-square error generalised decision-feedback equaliser (MMSE-GDFE), dither and lattice decoding. Building on this approach, in this paper we introduce a linear pre-coder for the MIMO-BC, which, although sub-optimal compared to the original DPC construction, may be regarded as a valuable option for practical applications because of its simplicity and its close-to-capacity achievable rates. We provide a theoretical analysis as well as numerical results which show the achievable rates of our linear pre-processing scheme compared to the DPC construction and to another recently proposed linear technique for throughput maximisation, based on gradient nulling.