Maximum-Likelihood Priority-First Search Decodable Codes for Combined Channel Estimation and Error Correction

• Published in: IEEE transactions on information theory Vol. 55; no. 9; pp. 4191 - 4203
• Main Authors: Chia-Lung Wu, Po-Ning Chen, Han, Y.S., Ming-Hsin Kuo
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Applied sciences; Channel coding; Channel estimation; Channels; Codes; Coding; Coding, codes; Complexity; Computational modeling; Computer simulation; Construction; Counting circuits; Decoding; Detection, estimation, filtering, equalization, prediction; Error correction; Error correction codes; Estimating techniques; Exact sciences and technology; Fading; fading channels; frequency-selective fading; Information theory; Information, signal and communications theory; Maximum likelihood decoding; Maximum likelihood estimation; Maximum likelihood method; MIMO; multipath channels; Searching; sequential decoding; Signal and communications theory; Signal, noise; Simulation; System performance; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Fading channels; Performance evaluation; Estimation error; Parameter estimation; Channel coding; Sequential decoding; Multipath channels; Search algorithm; Maximum likelihood decoding; Selective fading; Frequency selection; Simulation; frequency-selective fading; Channel estimation; Algorithm complexity; Simulated annealing; Recursive method; Metric; Error correction; Maximum likelihood; Computer codes
• ISSN: 0018-9448; 1557-9654
• DOI: 10.1109/TIT.2009.2025548

The coding technique that combines channel estimation and error correction has received attention recently, and has been regarded as a promising approach to counter the effects of multipath fading. It has been shown by simulation that a proper code design that jointly considers channel estimation can improve the system performance subject to a fixed code rate as compared to a conventional system which performs channel estimation and error correction separately. Nevertheless, the major obstacle that prevents the practice of such coding technique is that the existing codes are mostly searched by computers, and subsequently exhibit no apparent structure for efficient decoding. Hence, the operation-intensive exhaustive search becomes the only decoding option, and the decoding complexity increases dramatically with codeword length. In this paper, a systematic construction is derived for a class of structured codes that support joint channel estimation and error correction. It is confirmed by simulation that these codes have comparable performance to the best simulated-annealing-based computer-searched codes. Moreover, the systematically constructed codes can now be maximum-likelihoodly decoded with respect to the unknown-channel criterion in terms of a newly derived recursive metric for use by the priority-first search decoding algorithm. Thus, the decoding complexity is significantly reduced as compared with that of an exhaustive decoder.