EXIT chart analysis of turbo-BLAST receivers in Rayleigh fading channels

Turbo-BLAST is an advanced space-time layered architecture developed to approach the capacity limit of multiple-input multiple-output (MIMO) systems. Various multiuser detection (MUD) techniques have been explored in conjunction with turbo-BLAST to combat cochannel interference (CCI) and improve significantly the performance of MIMO systems in a multicell structure (Dai, H. et al., IEEE Trans. Wireless Commun.. vol.3. p.442-53, 2004). We study the extrinsic information transfer (EXIT) functions of several such turbo-BLAST receivers. We show that the EXIT functions, which work primarily for AWGN channels, are not accurate in giving quantitative performance estimates in a fading environment. A method that copes with this problem and yields reasonably accurate estimates of convergence rate and bit-error-rate is proposed. The performance of different turbo-BLAST receivers is compared in both single-cell and multicell scenarios.