Improved V-BLAST symbol detection using short block codes

We present a new iterative symbol detection and decoding scheme for coded V-BLAST architectures (ISDD-BLAST). In this scheme, V-BLAST blocks are spatially encoded using a short block code. Using a Tanner graph representation of the code´s parity-check matrix, as each symbol is detected, the detector is able to determine when an error has occurred. The detector then uses a modified bit-flipping algorithm to flip the least reliable bit, then greedily returns to the symbol changed, and continue with the detection sequence. When the greedy algorithm is permitted to reach up to a maximum of 1000 symbol detections, an 8times8, 8-PSK V-BLAST system using the proposed detection scheme shows an E_b=N₀ gain of about 7dB over an equivalently uncoded system. As ISDD-BLAST greedily searches for symbols until such time as a codeword is found, its average complexity at mid to high SNR values is only slightly greater than the original V-BLAST.