Code Designs for MIMO Broadcast Channels

Recent information-theoretical results show the optimality of dirty-paper coding (DPC) in achieving the capacity of the Gaussian multiple-input multiple-output (MIMO) broadcast channel (BC). This paper presents the first practical limit approaching DPC-based design for the MIMO BC. We start with Cover´s simplest two-user Gaussian BC and present a code design that operates 1.44 dB away from the capacity region boundary at a transmission rate of 1.0 bit per sample (b/s). Then we consider the non-degraded two-user MIMO fading BC with two transmit antennas. For this setup, the performance loss of our code design is 3.7 dB and 2.45 dB from the sum-rate capacity when the transmission rate for each user is 1.0 b/s and 2.0 b/s, respectively