未知噪声信息多径衰落信道的软判决度量生成

信道解码中的软判决技术需要利用信道噪声方差信息来产生软判决度量,而通常情况下,这一信息是未知和时变的。本文首先简要分析了信道噪声方差对软判决度量的影响,进而提出一种新的在多径衰落信道中估计时变噪声方差的方法,并利用该方法的估计结果为信道解码器生成软判决度量。将该算法应用于中国地面数字电视广播传输系统外接收机的仿真结果表明：与已有的信道噪声方差估计算法相比,本文算法具有收敛速度快、估计结果准确的优点,生成的软判决度量逼近于多径衰落信道的最优软判决度量。

Soft decision metric generation over a multipath fading channel with unknown noise information

The channel noise variance information is required by the soft decision for a channel decoder. However, such information is usually unknown and/or time varying. In this paper, the effects of channel noise variance on soft decision metric are analyzed. Then, a new channel noise variance estimation method applied to the multipath fading channel is presented to generate exact soft-decision metric for a channel decoder. Applying the proposed method to the outer receiver of Digital Terrestrial Multimedia Broadcasting（DTMB） system, simulation results indicate that the proposed method converges rapidly and the generated soft decision metric is very close to the optimal one.