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本文分析计算了在有同频道干扰和延时扩展多径干扰的快衰落信道中采用差分检波后分集合并的角调制系统的误码率特性。利用求留数的方法由合并输出的特征涵数导出其概率密度函数,进而得到一类统一的误码率公式。结果表明,分集合并技术不仅是一种有效的抗衰落措施,而且对抗同频道干扰和随机FM噪声干扰都非常有效。尤其当采用L-重分集时,由随机FM噪声引起的残留误码率被减小到无分集单一支路时的L次幂。但是合并接收不足以克服延时扩展多径干扰的影响。特别在大时延和强干扰的情况下,要有效克服延时多径所引起的码间干扰,还应配合使用纠错编码和自适应均衡等技术。
This paper analyzes and calculates the bit error rate (BER) characteristics of differential modulation and post-diversity diversity in fast fading channels with co-channel interference and delay spread multipath interference. By using the method of Bayesian number, the probability density function is derived from the characteristic culverts output by the merger, and then a uniform type of error rate formula is obtained. The results show that diversity combining technique is not only an effective anti-fading measure, but also is very effective against both co-channel interference and random FM noise interference. Especially when L-re-diversity is used, the residual error rate caused by random FM noise is reduced to the L-power of the unoccupied single branch. However, the combined reception is not enough to overcome the effect of delay spread multipath interference. Especially in the case of large delay and strong interference, it is necessary to effectively overcome the intersymbol interference caused by delayed multipath and should also use technologies such as error correction coding and adaptive equalization.