A Near-Capacity GDFE-Like Precoder with Reduced Feedback Overhead for MIMO Broadcast Channel

Downlink multi user multiple input multiple output (MU-MIMO) systems are of increasing importance in current and upcoming wireless applications. The improvement in data rates offered by such systems depends on the design of precoding schemes for the broadcast channel (BC) which is their theoretical generalization. A precoding scheme based on generalized decision feedback equalizer (GDFE) is known to achieve MIMO BC capacity. However, GDFE precoder suffers from huge computational complexity and feedback overhead that renders it unsuitable for practical systems. While the computational complexity has been dealt elsewhere, the feedback overhead issue has not yet been resolved. Thus in this paper we propose an algorithm to significantly reduce the feedback requirements of GDFE and show that the performance loss is minimal. We do this by first presenting a variant of the conventional GDFE algorithm, which we prove has the same theoretical performance.