BibTeX
@MISC{_mimospatial,
author = {},
title = {MIMO Spatial Multiplexing Systems with Limited Feedback},
year = {}
}
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Abstract
Abstract — This paper investigates the problem of transmit beamforming in MIMO spatial multiplexing (SM) systems with finite-rate feedback channel. Assuming a fixed number of spatial channels and equal power allocation, we propose a new design criterion for designing the codebook of beamforming matrices that is based on minimizing the capacity loss resulting from the limited rate in the feedback channel. Using the criterion, we develop an iterative design algorithm that converges to an optimum codebook. Under the i.i.d. channel and high SNR assumption, the effect on channel capacity of the finite-bit representation of beamforming matrix is analyzed. Central to this analysis is the complex multivariate beta distribution and tractable approximations to the Voronoi regions associated with the code points. Furthermore, to compensate for the degradation due to the equal power allocation assumption, we propose a multimode SM transmission strategy wherein the number of data streams is determined based on the average SNR. This approach is shown to allow for effective utilization of the feedback bits. I.
Keyphrases
mimo spatial multiplexing system limited feedback capacity loss optimum codebook spatial channel high snr assumption data stream new design criterion complex multivariate beta distribution feedback channel finite-rate feedback channel equal power allocation assumption multimode sm transmission strategy equal power allocation iterative design algorithm fixed number mimo spatial multiplexing effective utilization average snr limited rate channel capacity finite-bit representation code point voronoi region tractable approximation transmit beamforming
