A variable rate LDPC coded V-BLAST system

In this paper, we propose a V-BLAST system based on variable rate LDPC codes to improve the performance of a receiver when QR decomposition interference suppression combined with interference cancellation is used over independent Rayleigh fading channels. The different rate LDPC codes can be made by puncturing some rows of a given parity check matrix. The performance can be improved by assigning stronger LDPC codes in the lower layer than the upper layer, because the poor SNR of first detected data streams produces error propagation. Keeping the same overall code rates, the V-BLAST system with different rate LDPC codes has better performance (in terms of bit error rate) than with constant rate LDPC codes. The BER performance has been evaluated in independent Rayleigh fading channels through computer simulation.