宽带网络的未来DOCSIS2.0--HFC宽带接入网的未来标准

目前，HFC宽带接入网络在全球已经有了很大发展，特别在北美和欧洲已经占有相当份额的市场。HFC宽带接入网的主要标准DOCSIS在现行的1.0和1.1版本的基础上又推出了DOCSIS2.0版本。针对DOCSIS2.0与DOCSIS1.0/1.1的区别，进行了深入的分析，着重介绍了DOCSIS2.0的优势和特点，并对它们未来的市场前景进行了分析预测。     

一种基于固定TDMA的无冲突动态时隙分配算法

本文提出了一种适用于Adhoc网络的动态时隙分配TDMA算法——IP-TDMA算法,该算法以一种新颖的方式在固定TDMA的基础上叠加了优先级竞争机制,既有最差性能保障,又有较高信道利用率。通过采用一种特殊的帧结构,P-TDMA算法还可以避免信令分组的碰撞,是一种有效而又可靠的广播动态时隙分配TDMA算法。仿真结果表明,无论在吞吐量还是迟延方面,P-TDMA算法都比固定TDMA表现出更好的性能。     

Two-level protection and guarantee for multimedia traffic in IEEE 802.11e distributed WLANs

In order to support multimedia applications such as voice and video over the wireless medium, a contention-based channel access function, called Enhanced Distributed Channel Access (EDCA), has been developed in the emerging standard IEEE 802.11e. In the EDCA, differentiated channel access is provided for different traffic classes. In this paper, we propose a two-level protection and guarantee mechanism for voice and video traffic in the EDCA-based distributed wireless LANs. In the first-level protection, the existing voice and video flows are protected from the new and other existing voice and video flows via a distributed admission control with tried-and-known and early-protection enhancements. In the second-level protection, the voice and video flows are protected from the best-effort data traffic by adopting frame-based and limit-based data control mechanisms. Performance evaluations are conducted in terms of throughput, delay, transmission limit, number of collisions, and throughput square relative difference. Extensive simulation results demonstrate that the proposed two-level protection and guarantee mechanism is very effective in terms of the protection and guarantee of existing voice and video flows as well as the utilization of the channel capacity. An early version of this paper was presented at IEEE INFOCOM 2004.     

基于SDL的无线传感器网络MAC协议的设计与实现

文章首先介绍了无线传感器网络目前采用的典型的MAC协议,并利用SDL语言设计了基于无线信道随机竞争方式的无线传感器网络MAC层协议。协议的实现证明用SDL语言进行通信协议设计可以保证协议的逻辑正确性,并且可以有效地缩短协议开发周期。     

基于IEEE802.16e的头压缩的设计与实现

介绍了IEEE802.16e协议中MACCS子层的头压缩机制,并结合MACCS子层的特点,提出了一种IEEE802.16e协议栈开发中MACCS子层头压缩模块的实现方案。通过对已有头压缩算法的研究分析,并结合IEEE802.16e协议的特性提出了一种适合宽带无线通信系统的头压缩算法。     

APON中MAC协议的研究现状

以高度概括来观察MAC协议,分别从APON承载的业务、带宽分配的对象、承载请求信息的通道和动态带宽分配算法等几个方面介绍了当前MAC协议研究的进展。最后,提出了一个有待研究的新问题。     

无线MESH网络中的多信道MAC协议概述

分析了无线mesh网络多信道应用的必要性;介绍了多信道应用的现状,列出了几种典型的多信道协议;对各种多信道协议进行了分析,总结了其优缺点;提出对多信道未来改进方向的看法.     

MAC层的多媒体同步研究

以往的协议主要针对有线环境,要求数据无差错实时地传输,而在无线环境下,满足该要求的代价非常大。首先介绍多媒体同步的概念,以及要求,指出在未来无线通信环境中,进行MAC层同步的必要性;然后提出协议,通过仿真分析,结果表明新协议能够较好地满足未来移动通信的需要。     

A fuzzy logic cooperative MAC for MANET

In both wireless local area networks（WLAN） and mobile ad hoc networks（MANET）, the 1EEE 802.11e medium access control （MAC） protocol is proposed for an effective quality of service （QoS） solution. A number of studies have been done to enhance the performance of 802.11e in MANET by independently adjusting contention window （CW） size of each access category （AC） in every node. However, without the cooperation between the high priority flows and lower priority flows, the QoS goal of high priority flows cannot achieve effectively. In this article, a fuzzy logic based cooperative MAC protocol （FLCMAC） is proposed to cooperate amongst network flows and dynamically adjust access probability of each low priority flow affecting the high priority flows to satisfy their QoS requirement. The simulation results indicate that compared to the enhanced distributed channel access （EDCA） scheme of 802.11e, the FLCMAC consistently excels, in terms of throughput and delay under moderate and heavy background traffic both in single-hop and multi-hop scenarios.