一种M-FSK信号的能量度量Viterbi软译码算法性能分析

Performance Analysis of Energy Metrics for Viterbi Soft Decoding Algorithm Based on M-FSK Signal

Viterbi译码算法广泛应用于无线数字通信系统,一般采用比特对数似然信息(LLR)作为译码器的输入。针对M-FSK信号,该文提出一种采用信号解调得到的M维能量信息,直接作为译码器分支度量值,并给出了相应的Viterbi译码算法。在加性高斯白噪声(AWGN)和瑞利(Rayleigh)衰落信道下对所提算法的BER性能进行了理论推导,得到了闭合表达式。通过仿真验证了理论推导的正确性,与常规Viterbi算法相比,所提算法避免了比特LLR和分支度量值的计算,降低了算法复杂度和减少了信息损失,提高了M-FSK信号软解调Viterbi译码算法的BER性能,是一种更适用于工程实现的M-FSK信号的Viterbi译码算法。

The Viterbi decoding algorithm is widely used in the wireless digital communication system, generally using the bit Log-Likelihood Ratio （LLR） as its input. For an M-ary Frequency Shift Keying （M-FSK） signal, a corresponding Viterbi decoding algorithm by directly adopting the M-dimensions energy information of the signal demodulation as the decoder branch metrics is proposed. This paper analyzes the theoretical performance of the proposed algorithm in the AWGN and the Rayleigh fading channels, and the upper bound for closed-form expressions of the Bit Error Rate （BER） performance are derived. The validity of the theoretical derivation is demonstrated by the simulations. Compared with the existing Viterbi algorithm, the proposed scheme can avoid the computing of the bit LLR and the branch metric, also it can descend the complex of the algorithm and decrease the loss of the information, improve the BER performance in the presence of Viterbi decoding algorithm which based on the M-FSK signal soft demodulation. Thus, the proposed scheme is a Viterbi decoding algorithm that is more adaptive to the actual project based on the M-FSK＇ signal.