Bit-Clusters Trellis Search Based Iterative MIMO Detection Algorithm

Abstract

A bit-clusters trellis-search (BCTS) based soft-input soft-output detection algorithm is proposed for iterative Multiple-Input Multiple-Output (MIMO) receivers. Compared to the symbol nodes trellis-search (SNTS) based MIMO detection algorithm, which significantly reduces the search complexity by limiting the number of candidates in each trellis stage compared to sphere decoding algorithm, the BCTS algorithm proposed in this article further reduces the number of candidates in the trellis. In the BCTS algorithm, we replace the symbol node in SNTS algorithm with bit-cluster that represents several relative symbols whose corresponding bit is 0 or 1 while the other bits are not concerned. Because the bit-cluster number is fewer than the symbol node number, the search complexity of proposed BCTS algorithm is much less than that of the SNTS algorithm. The simulation results show, by transforming symbol nodes to bit-clusters in trellis-search detection, the performance is improved nearly 0.5 dB when the bit-error-ratio reaches 10 −4 ; the complexity analysis shows the number of partial-Euclidian-distance (PED) comparisons and PED computations are approximately three and one times fewer than that of the SNTS algorithm respectively when constellation size is beyond 16. And this tendency will be more obvious with the transmit antenna number and constellation size increasing.