Approaching the MIMO Capacity with a Low-Rate Feedback Channel in V-BLAST
- PDF / 980,951 Bytes
- 10 Pages / 600 x 792 pts Page_size
- 98 Downloads / 160 Views
Approaching the MIMO Capacity with a Low-Rate Feedback Channel in V-BLAST Seong Taek Chung STAR Laboratory, Stanford University, Stanford, CA 94305-9515, USA Email: [email protected]
Angel Lozano Wireless Research Laboratory, Lucent Technologies, 791 Holmdel-Keyport Road, Holmdel, NJ 07733, USA Email: [email protected]
Howard C. Huang Wireless Research Laboratory, Lucent Technologies, 791 Holmdel-Keyport Road, Holmdel, NJ 07733, USA Email: [email protected]
Arak Sutivong Information Systems Laboratory, Stanford University, Stanford, CA 94305-9510, USA Email: [email protected]
John M. Cioffi STAR Laboratory, Stanford University, Stanford, CA 94305-9515, USA Email: cioffi@stanford.edu Received 8 December 2002; Revised 30 October 2003 This paper presents an extension of the vertical Bell Laboratories Layered Space-Time (V-BLAST) architecture in which the closedloop 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. Keywords and phrases: adaptive antennas, BLAST, interference cancellation, MIMO systems, space-time processing, discrete bit loading.
1.
INTRODUCTION
Information theory has shown that the rich-scattering wireless channel can support enormous capacities if the multipath propagation is properly exploited, using multiple transmit and receive antennas [1, 2, 3]. In order to attain the closed-loop multiple-input multiple-output (MIMO) capacity, it is necessary to signal through the channel’s eigenmodes with optimal power and rate allocation across those modes [4, 5]. Such an approach requires instantaneous chan-
nel information feedback from the receiver to the transmitter, hence a closed-loop implementation. Furthermore, a very specialized transmit structure is required to perform the eigenmode signaling. Therefore, it is challenging to incorporate the closed-loop MIMO capacity-achieving transmitreceive structures into existing systems. Open-loop schemes that eliminate the need for instantaneous channel information feedback at the transmitter have also been proposed [6, 7, 8, 9, 10, 11]. These schemes can be divided into two categories: multidimensional coding
Approachin
Data Loading...
