HFC网络中上行信道的MAC层协议性能分析

HFC(Hybrid Fiber Coaxial)作为一种主要接入网络,近年来受到了越来越深入的研究.HFC网络具有独特的树形-分支结构,其上、下行信道在频段上相互隔离,下行信道带宽较大,是一对多的广播信道,上行信道带宽较小,是多对一的共享信道.因此HFC网络的MAC(Medium Access Control)层协议设计重点,在于如何解决共享信道的接入冲突问题,以及如何提高上行信道的利用率和降低上行信道的接入延时.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.通过对MCNS(The Multimedia Cable Network System)提出的MAC层协议——DOCSISv1.0(Data-Over-Cable Service Interface Specifications version 1.0进行仿真,有力证实了本文的分析结果,对我们进一步深入研究HFC网络接入技术具有很好的指导意义.

Performance Analysis of Upstream Channel MAC Layer Protocol in HFC Networks

As a key access network,HFC( Hybrid Fiber Coaxial ) network has been deeply studied recently.HFC network has the special tree and branch topology.Its upstream and downstream channels are separate from each other in frequency band.The upstream channel is a point to multipoint broadcasting channel with a wider bandwidth,while the downstream one is a multipoint to point share medium with a narrower bandwidth.So,the most key issues in MAC protocol design of the HFC network are focused on how to resolve the collision efficiently,how to improve the bandwidth utility and how to lower the access time delay while using upstream channels.This paper theoretically analyzed the main factors that affect these performances of a MAC protocol based on most popular designs.Also we studied the performance of DOCSIS v1.0 MAC protocol through simulation.The test results approve our analysis well.This paper can give us some guidance in our further exploration of HFC access technology.