中文摘要：

提出了一种适用于所有M-QAM软判决解映射的简化算法，并将其扩展到不对称的二维QAM解映射中，如DTMB中的32-QAM。并以32-QAM为例，用计算机仿真比较了不同算法的编码系统误码率和解码时间等性能。结果表明，在降低M-QAM软判决解映射的判决复杂度时，该简化算法没有损失信噪比，性能良好，适用于DTMB系统。

英文摘要：

A new simplified soft-output demapping algorithm for M-QAM is proposed in this paper, and the method is expanded to unsymmetric 2-D QAM demapping such as 32-QAM in DTMB. Then taking 32-QAM for example, the performances of DTMB system with different algorithms are simulated, such as bit error rate and decoding time. The results show that the simplified algorithm decreases the soft-output demapping complexity without the loss of signal-to-noise ratio and has acceptable performance for DTMB system.