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| Iterative Carrier Recovery Based on Soft Decision Metrics of LDPC Decoding |
| Bao Jian-rong①; Zhan Ya-feng②; Lu Jian-hua①② |
| ①Department of Electronic Engineering, Tsinghua University, Beijing 100084, China; ②Tsinghua Space Center, Tsinghua University, Beijing 100084, China |
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Abstract It is difficult to recovery carrier at rather low SNR (≤2 dB). An iterative carrier recovery via soft decision metrics of LDPC decoding is proposed. By maximizing the sum of the absolute value of the soft decision metrics of LDPC decoding with search window aided simplex algorithm, it can obtain accurate carrier estimate which will be compensated. Meanwhile, it can be combined with the Costas loop with LDPC decoding feedback to eliminate the residual carrier offsets. Simulation results indicate that it can overcome the problems of phase ambiguity, cycle slip and so on, and the performance of the QPSK system with it under carrier offsets is just within 0.1 dB of the ideal performance at the cost of some more computation complexity.
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Received: 14 October 2008
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2009, Vol. 31 
