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由于时频相信号综合了多种信号形式的优点,可以具有良好的抗衰落性能、抗多径符号干扰性能,且易于实现。所以近年来在对流层散射数字通信系统的研究中颇受重视。但是,对于信号形式比较复杂的时频相通信系统,目前还难于写出误码率的解析表达式,而只能写出在高信噪比条件下误码率的界。通常这种界不适用于估计误码率大于10~(-4)范围内的性特,另一方面,误码率的理论计算公式一般都是在理想条件下导出的,没有考虑匹配滤波器不理想和各频率之间存在相关性等实际因素的影响。Bello等人利用计算机模拟了几种时频相通信系统在理想条件下的性能。这里利用类似的统计试验方法,模拟了几种时频相自适应通信系统的性能,以及实际系统中存在的匹配滤波器不理想和各频率之间相关性对检测性能的影响。本文首先讨论时频相自适应通信系统的数字模型,然后介绍模拟方法,最后对一些模拟结果进行了分析讨论。
As the time-frequency phase signal combines the advantages of a variety of signal forms, it can have good anti-fading performance, anti-multipath symbol interference performance, and easy to implement. In recent years, therefore, much attention has been paid to the research of tropospheric scatter digital communication system. However, it is still difficult to write an analytical expression of the bit error rate for time-frequency phase communication systems with relatively complicated signal forms, but can only write the bound of the bit error rate under high signal-to-noise conditions. Usually this kind of world is not suitable for estimating the bit error rate greater than 10 ~ (-4) range of special, on the other hand, the bit error rate of the theoretical formula are generally derived under ideal conditions, did not consider the matched filter Not ideal and the correlation between the various factors such as the actual impact. Bello et al. Used computers to simulate the performance of several time-frequency phase communication systems under ideal conditions. Similar statistical test methods are used here to simulate the performance of several kinds of time-frequency adaptive communication systems, as well as the imperfect matching filters and the influence of the correlation between different frequencies on the detection performance in practical systems. This paper first discusses the digital model of adaptive time and frequency communication system, and then introduces the simulation method. Finally, some simulation results are analyzed and discussed.