A Fast Constrained Sphere Decoder for Ill Conditioned Communication Systems

• Published in: IEEE communications letters Vol. 14; no. 11; pp. 999 - 1001
• Main Authors: Kanaras, I, Chorti, A, Rodrigues, M R D, Darwazeh, I
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.11.2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Applied sciences; Coding, codes; Communication systems; Complexity theory; Conditioning; Constraints; Decoders; Decoding; Exact sciences and technology; Expenses; Frequency division multiplexing; Hamming distance; Hyperspheres; ill-conditioned; Information, signal and communications theory; MIMO; Optimization; Reduction; regularisation; Signal and communications theory; Signal to noise ratio; Sphere decoder; Telecommunications and information theory; Performance evaluation; regularisation; ill-conditioned; Spanning tree; Telecommunication system; Heuristic method; Decoding; Sphere decoder; Algorithm; Computational complexity; Signal to noise ratio; Large scale system
• ISSN: 1089-7798; 1558-2558
• DOI: 10.1109/LCOMM.2010.093010.100918

This letter proposes a fast constrained sphere decoder for ill conditioned communications systems that exhibits less complexity than but similar performance to the generalised sphere decoder. The operational principle is based on i) the reduction of the search space by setting the hypersphere initial radius to be equal to the distance to a semidefinite program (SDP) estimate; and ii) the introduction of a heuristic pruning rule to limit the GSD spanning tree. The new algorithm achieves significant reduction in the required computational effort at the expense of a small error penalty for large dimensional systems in low signal to noise ratio (SNR) regimes.