Title :
Improved K-Best Sphere Detection for Uncoded and Coded MIMO Systems
Author :
Han, Shuangshuang ; Cui, Tao ; Tellambura, Chintha
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of Alberta, Edmonton, AB, Canada
fDate :
10/1/2012 12:00:00 AM
Abstract :
The conventional K-best sphere decoder (KSD) keeps the best K nodes at each level of the search tree. In addition to retaining the best K nodes, we also consider all the nodes whose costs are within a certain margin of the cost of the Kth best node. The resulting algorithm is called improved K-best sphere decoder (IKSD). Three IKSD variants are considered in this letter, which are fixed threshold, normalized threshold and adaptive threshold IKSD. The proposed IKSD requires a smaller K (indicating lower complexity) while still achieving a better and near optimal performance compared to the conventional KSD. These gains are confirmed by the simulation results. For example, for the fixed threshold IKSD in a 4 x 4 16-QAM multiple-input multiple-output (MIMO) system, with K=2, it achieves the same performance as the conventional KSD (K=16), yielding about 80% complexity savings. For coded MIMO systems, the IKSD is also extended as a list sphere decoder for joint iterative detection and decoding.
Keywords :
MIMO communication; adaptive codes; adaptive decoding; iterative decoding; quadrature amplitude modulation; 16-QAM multiple-input multiple-output system; K-best sphere decoder; adaptive threshold IKSD; coded MIMO system; fixed threshold IKSD; improved K-best sphere detection; iterative decoding; iterative detection; near optimal performance; normalized threshold IKSD; uncoded MIMO system; Complexity theory; Decoding; Indexes; Iterative decoding; MIMO; Signal to noise ratio; Wireless communication; MIMO; ML; sphere decoder; tree search; wireless communications;
Journal_Title :
Wireless Communications Letters, IEEE
DOI :
10.1109/WCL.2012.070312.120472