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Using DS-CDMA to Realize Bi--direction Communications in CATV Network 直接使用码分多址序列实现双方向通信有线电视网络 Abstract：In this paper， a new scheme using DS-CDMA to realize Bi—Direction communications in CATV network is addressed． As a colusion，we can find that this is an economical realization of access network，having good performances compared with some other schemes． 文摘:在这篇文章中,一个新的计划在有线电视使用码分多址实现双向通信网络解决。作为一个解决方案,我们可以发现这是一个经济的实现访问网络,与其他方案相比具有良好的性能。 Introduction 1.介绍 With the development of modern communications, the access network technology is showing its great importance day by day. 随着现代通信的发展,接入网技术正显示出其重视。 The access network technology can be divided into four categories：advanced cotton cable technology， FITL system，CATV network and WLL system． 接入网技术可分为四类:先进的棉花电缆技术,光纤环路系统、有线电视网络和系统广泛分布有线电视网络。 The popularly distributed CATV network，for its relatively low price and good broad band transport characteristics， may be the most prospective media to realize multi-service communications including voice， data and moving picture． 因其相对较低的价格和良好的宽带运输特点,可能是最准媒体实现多业务通信包括语音,数据和移动图像。 In this paper，a new scheme using DS—CDMA to realize Bi-Direction communications in CATV network is addressed． 在本文使用码分多址的新方案在有线电视网络实现双向通信地址。 As a colusion，we can find that this is economical and with good performances compared with some other schemes． 作为一个解决方案,我们可以发现这是经济和与其他方案相比具有良好的性能。 2．Existing CATV Network 2.现有的有线电视网络 The CATV network is a hierarchical and single-direction system，as we can see from Fig．1， composed of three parts： front end part，transportation part and user distribution part. In the tranportation lines，there are many equipments such as amplifiers， branches and distributors． 有线电视网络层次和发展性系统,从图1中我们可以看到,由三部分组成:前端部分,运输和用户分配部分。交通运输线路,有很多设备如放大器、分支机构和分销商。 3.Bi-direction System Design 3.双向系统设计 In order to make Bi—direction communication available， we divide the whole bandwidth into twos：0—50 MHz as the upward passway and 50-400 MHz as the downward passway． It is also needed to change the e