On Optimum Power Allocation for the V-BLAST

Abstract

A unified analytical framework for optimum power allocation in the unordered V-BLAST algorithm and its comparative performance analysis are presented. Compact closed-form approximations for the optimum power allocation are derived, based on average total and block error rates. The choice of the criterion has little impact on the power allocation and, overall, the optimum strategy is to allocate more power to lower step transmitters and less to higher ones. High-SNR approximations for optimized average block and total error rates are given. The SNR gain of optimization is rigorously defined and studied using analytical tools, including lower and upper bounds, high and low SNR approximations. The gain is upper bounded by the number of transmitters, for any modulation format and type of fading channel. While the average optimization is less complex than the instantaneous one, its performance is almost as good at high SNR. A measure of robustness of the optimized algorithm is introduced and evaluated. The optimized algorithm is shown to be robust to perturbations in individual and total transmit powers. Based on the algorithm robustness, a pre-set power allocation is suggested as a low-complexity alternative to the other optimization strategies, which exhibits only a minor loss in performance over the practical SNR range.

Accepted by IEEE Transactions on Communications, Apr. 2007

References in corpus (1)

• Symbol Error Rates of Maximum-Likelihood Detector: Convex/Concave Behavior and Applications

Cited by in corpus (6)

• Error Rates of the Maximum-Likelihood Detector for Arbitrary Constellations: Convex/Concave Behavior and Applications
• On Outage and Error Rate Analysis of the Ordered V-BLAST
• Optimum Power and Rate Allocation for Coded V-BLAST: Average Optimization
• On Convexity of Error Rates in Digital Communications
• Error Rates of Capacity-Achieving Codes Are Convex
• Bit Error Rate is Convex at High SNR