【作者】 黄建平；

【导师】 汪晓宁；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2009， 硕士

【摘要】 频带拥挤是现代民用通信中比较严重的问题。在跳频通信中,通过实现多用户共享频带来解决频带拥挤问题。但随着网络容量增大,远近效应越来越严重。在跳频通信中,为了满足网络性能要求,必须解决多址干扰问题。跳频通信系统本身又是一个自干扰系统,系统中各用户之间的干扰比较突出。如果相互干扰的概率为500跳中碰撞一次,则比特差错概率BER为10^-3。将造成大量信息丢失,影响通信质量甚至造成通信中断。跳频通信中有许多方法克服多址干扰。途径之一是研究设计一种尽可能低的汉明互相关性的工程实用码型,途径之二是运用一些消除或减弱干扰的跳频技术,改善系统性能,这就包括自适应跳频技术,差分跳频技术等。本文试图结合这两种途径,以期获得系统更好的抗多址干扰性能。首先选择一类无碰撞区（No-Hit-Zone简称NHZ）跳频码,该类NHZ跳频码仅在序列特定相互位移处出现周期碰撞频点,而其它位移处不会发生频率碰撞。然后,针对该类跳频码的特点,将自适应跳频思想与之相结合,建立基于一类NHZ跳频序列的自适应跳频系统,目的是最大限度地改善系统抗多址干扰的能力。本文利用Simulink搭建该自适应跳频通信系统仿真平台。MATLAB语言编写用户自定义模块,作为该自适应跳频通信系统的仿真工具。对该异步NHZ跳频序列的自适应跳频系统与采用NHZ跳频序列的常规跳频系统,分别在最差情况与一般情况下,进行了仿真研究。仿真结果表明,所提出的基于一类NHZ跳频序列自适应跳频系统通过替换该无碰撞区跳频序列中周期碰撞的频点,不论是在坏信道数还是误码率上,都较常规无碰撞区跳频系统有了一定的改善,提高了系统抗多址干扰的能力,改善了系统的整体误码率性能。更多还原

【Abstract】 Band congestion problem is the serious problem in the modern civilian communications.In the frequency-hopping communication,it solves the overcrowding problem that the realization of multi-user shared frequency band. However,with network capacity increasing,near-far effect is more and more serious.In order to meet network performance requirements,it must deal with the issue of multiple access interference in the frequency -hopping communication.It is a self-interference system for Frequency-hopping communication system and interference between the users is more serious.If it happens one collision for 500 jumps,the bit error probability（BER） is 10^-3.It affects the quality of communication and even disrupts the communication for a large amount of information lossing.In the frequency-hopping communications,in order to overcome the multiple access interference（MAI）,there has been a number of ways.One way is to research and design practical hopping code with a hamming cross-correlation as low as possible.Other way is to improve the system by technology of eliminate or reduce interference,which includes Adaptive Frequency Hopping（AFH）, Correlated Hopping Enhanced Spread Spectrum（CHESS） and so on.This thesis combines of these two ways to improve the performance of anti-MAI.First of all,a No-Hit-Zone（NHZ） hopping code with a low cross-correlation is choosed that only occurrs the frequency collision at a particular displacement of cycle and will not collisions in other displacement of cycle.Then, according to the characteristics of No-Hit-Zone（NHZ） hopping code,we propose the No-Hit-Zone hopping communication system depends on the adaptive frequency hopping thinking.A new adaptive frequency hopping communication system using for NHZ hopping code was studied.The purpose is to do the best to reduce the multiple access interference of system. In this thesis,the author builds the adaptive frequency hopping communication system simulation platform with SIMULINK tool.In the user-defined modules of the adaptive frequency hopping communication system simulation platform,Matlab language is used as the programming tool.In the worse case and normal case,the author does a simulation study with the asynchronous adaptive frequency hopping communication system using for NHZ hopping code and the asynchronous non-adaption frequency hopping communication system using for NHZ hopping code.Simulation results prove that the system that substitutes the period hit frequency of the No-Hit-Zone（NHZ） hopping sequences is better than traditional system.Both in the number of bad channels or the bit error rate,it decreases the Multi-Access interference and improves the integral bit error rate performance of the system.更多还原