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Báo cáo hóa học: " Minimum decoding trellis length and truncation depth of wrap-around Viterbi algorithm for TBCC in mobile WiMAX"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Minimum decoding trellis length and truncation depth of wrap-around Viterbi algorithm for TBCC in mobile WiMAX | Liu and Tsai EURASIP Journal on Wireless Communications and Networking 2011 2011 111 EURASIP Journal on . http jwcn.eurasipjournals.eom content 2011 1 111 Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access Minimum decoding trellis length and truncation depth of wrap-around Viterbi algorithm for TBCC in mobile WiMAX Yu-Sun Liu and Yao-Yu Tsai Abstract The performance of the wrap-around Viterbi decoding algorithm with finite truncation depth and fixed decoding trellis length is investigated for tail-biting convolutional codes in the mobile WiMAX standard. Upper bounds on the error probabilities induced by finite truncation depth and the uncertainty of the initial state are derived for the AWGN channel. The truncation depth and the decoding trellis length that yield negligible performance loss are obtained for all transmission rates over the Rayleigh channel using computer simulations. The results show that the circular decoding algorithm with an appropriately chosen truncation depth and a decoding trellis just a fraction longer than the original received code words can achieve almost the same performance as the optimal maximum likelihood decoding algorithm in mobile WiMAX. A rule of thumb for the values of the truncation depth and the trellis tail length is also proposed. Keywords WiMAX tail-biting convolutional codes circular decoding 1 Introduction The IEEE 802.16 defines the wireless metropolitan area network MAN technology that is commonly referred to as WiMAX. The IEEE 802.16 includes two sets of standards IEEE 802.16-2004 802.16d 1 for fixed WiMAX and IEEE 802.16-2005 802.16e 2 for mobile WiMAX. In mobile WiMAX tail-biting convolutional codes TBCCs 3 are designated as the mandatory error-correcting codes. In the WiMAX transmitters data bursts are divided into data blocks and each data block is separately encoded by a TBCC encoder. The circular decoding algorithm 4-6 in which the wraparound Viterbi algorithm traverses on the .