EURASIP Journal on Applied Signal Processing 
Volume 2004 (2004), Issue 5, Pages 762-771
doi:10.1155/S1110865704312035

Approaching the MIMO Capacity with a Low-Rate Feedback Channel in V-BLAST

Seong Taek Chung,1 Angel Lozano,2 Howard C. Huang,2 Arak Sutivong,3 and John M. Cioffi1

 1STAR Laboratory, Stanford University, Stanford, 94305-9515, CA, USA
2Wireless Research Laboratory, Lucent Technologies, 791 Holmdel-Keyport Road, Holmdel 07733, NJ, USA
3Information Systems Laboratory, Stanford University, Stanford, 94305-9510, CA, USA
Received 8 December 2002; Revised 30 October 2003

Abstract

This paper presents an extension of the vertical Bell Laboratories Layered Space-Time (V-BLAST) architecture in which the closed-loop multiple-input multiple-output (MIMO) capacity can be approached with conventional scalar coding, optimum successive decoding (OSD), and independent rate assignments for each transmit antenna. This theoretical framework is used as a basis for the proposed algorithms whereby rate and power information for each transmit antenna is acquired via a low-rate feedback channel. We propose the successive quantization with power control (SQPC) and successive rate and power quantization (SRPQ) algorithms. In SQPC, rate quantization is performed with continuous power control. This performs better than simply quantizing the rates without power control. A more practical implementation of SQPC is SRPQ, in which both rate and power levels are quantized. The performance loss due to power quantization is insignificant when 4–5 bits are used per antenna. Both SQPC and SRPQ show an average total rate close to the closed-loop MIMO capacity if a capacity-approaching scalar code is used per antenna.