This dissertation gives theoretical analysis of the main factors that affect these performances of a mac protocol , based on most popular designs . this dissertation presents a new technology that based on aloha and s - cdma and theoretically analyzed the character of hfc system which use the new technology , such as the 本文结合当前hfc网络中主要mac层协议的设计思想从本质上分析了影响协议性能的关键因素，结合上行信道的利用率和数据传输延时这两方面的性能从理论上分析了hfc网络上行信道的传输机制，并对分析结果进行了仿真。
Presently , the apon system adopts tdma as the access mode on the uplink . it requires not too much in terms of optical performance , but it requires more complex electronic equipment ( e . g . , complex synchronized timing , ranging and delay control technolgies ) to avoid the collision of uplink information packets 目前apon系统在上行信道中采用时分多址的接入方式，它对光性能方面的要求不高，但它要求更复杂的电子设备，如要求复杂的同步定时、测距和延时控制技术，以避免上行信息分组产生碰撞。
In this paper , after introduction of the code division multiple access ( cdma ) and orthogonal multicarrier ( mc ) technique , the system model of mc - cdma is analyzed and the bit error rate ( ber ) performance in downlink and uplink channel is shown in awgn channel by computer simulation 本文在码分多址技术和正交多载波技术原理基础上，分析了高斯白噪声信道中多载波码分多址( mc - cdma )系统的数学模型，并且使用不同的扩展码对下行信道和上行信道误码率性能分别作了计算机仿真分析。
3 . we propose a new spreading sequence design scheme . in the uplink , using golay sequence , cinew sequence or zadoff - chu sequence , in the downlink , using wh sequence as the spreading sequence , we can control the papr of mc - cdma below 7db and ber below le - 3 ( snr = 20db ) 提出mc - cdma中扩频序列的新型设计方案，在上行信道，采用golay序列， cinew序列或zadoff - chu序列，在下行信道，采用wh序列作为扩频序列可以控制mc - cdma峰平比在7db以内，在信噪比为20db时，系统误码率小于1e - 3 。
Chapter 2 systemically demonstrates the parts of the system described in this paper , introduces the working principles of system ' s top and bottom communication channels , discusses the modularization design method in the master station software development . in the end of this chapter , the main function of the system is briefly introduced 第2章系统地阐述了电力远程监测管理系统的构成，介绍了系统上行信道、下行信道的工作原理，论述了主站软件的模块化设计思想、简要介绍了系统的主要功能。
In the hfc network , the uplink channel is applied a spectrum of 5 to 42mhz . although such a spectrum is of good attenuation characteristics , one fact is that other services also share the same spectrum , making the noise introduction a serious concern . also the noise will gradually accumulate , thus severely affecting the transmission performance of cablemodem 在hfc网络中，上行信道采用5 ~ 42mhz的频带，虽然这一频带具有良好的衰减特性，但是因为其他服务也采用这一频带，所以引入噪声成了一个严重的问题，并且这个噪声将逐步积累，严重地影响cablemodem的传输性能。
We designed a wireless asymmetric physical layer link model with a direct sequence spread spectrum system as a transmitted reference . uplink and downlink are both one - way links connected by an ip tunneling . uplink is consisted with the narrowband radio data link of the warfighter information networks ( win ) 研究了无线非对称链路，提出了一种用参考法直接序列扩频( dsss )实现的无线非对称数据传输的物理层链路模型：利用现有战斗员信息网电台的窄带数据链作为上行信道，通过ip隧道技术保证单向链路的连通性。
