ABSTRACT
This chapter provides an overview of feedback techniques for multiple-input-multiple-output (MIMO) communication channels. Wireless innovations are improving bandwidth efficiency and reducing the deleterious effects of fading in wireless communication channels. Multiple antennas offer high capacity, enhanced resistance to interference, and reductions in fading thanks to diversity when arrays are used at both transmitter and receiver in a MIMO configuration. The chapter describes the problem of channel quantization and reviews related work. It introduces the notion of limited feedback MIMO communication. The chapter discusses two approaches to limiting feedback: direct channel quantization and quantized signal adaptation. It describes various algorithms for quantized signal adaptation for narrowband channels. The chapter examines their performance in some practical correlated channels. It explains the extension to broadband MIMO-Orthogonal Frequency Division Multiplexing channels. The chapter also discusses per-tone quantization and interpolation for exploiting the correlation of adjacent subcarriers.
