无线局域网媒体接入控制层的性能研究

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1、河南科技大学 硕士学位论文 无线局域网媒体接入控制层的性能研究 姓名：聂世群 申请学位级别：硕士 专业：计算机应用技术 指导教师：刘伟 20080501 摘 要 I 论文题目：无线局域网媒体接入控制的性能研究 论文题目：无线局域网媒体接入控制的性能研究 专 业：计算机应用技术 专 业：计算机应用技术 研 究 生：聂世群 研 究 生：聂世群 指导教师：刘伟 指导教师：刘伟 摘 要 摘 要 无线局域网(WLAN)作为其中一种无线接入网络，凭借移动灵活、保密性 强、架设与维护容易等优点，越来越引起研究者和消费群体的关注。以 IEEE 802.11 为标准的无线局域网已经在全球范围内得到接受和广泛应用

2、.传统的 IEEE 802.11 主要是为了能很好地支持数据业务的传输，但随着无线局域网系统中多媒 体业务应用需求的迅速增长，在无线局域网中实现对音频、视频等多媒体业务的 服务质量(QoS)保证的需求已成为亟需解决的问题。媒体接入控制(MAC)层的信 道接入技术是提供服务质量保证的重要环节，因此研究无线局域网 MAC 层接入 技术具有重要的意义。MAC 层接入方式主要有竞争接入和集中控制接入两种。 本文主要研究竞争接入方式，即分布式协调功能(DCF)和增强分布式协调功能 (EDCA)。本文在分析 IEEE802.11 协议和 IEEE802.11e 协议的基础上，分别在不 同业务环境下，对比分

3、析了分布式协调功能机制和增强分布式协调功能机制。仿 真结果验证了饱和条件下增强分布式协调功能机制对业务的区分能力，提高了高 优先级业务的吞吐量和媒体接入延迟性能；还研究了调整竞争窗口和仲裁帧间隔 对无线局域网的吞吐量和媒体接入延迟性能的影响，仿真结果表明参数仲裁帧间 隔能够改变业务的媒体接入延迟，竞争窗口能够影响系统的整体性能。另外，对 饱和业务条件下增强分布式协调功能机制的性能分析模型进行了改进，新模型能 够更准确的反映网络状况，其中重点分析了增加传输机遇(TXOP)后系统的饱和 吞吐量。最后通过仿真验证，在饱和业务条件下，随着传输机遇的增加高优先级 业务的吞吐量提高了，而低优先级业务的吞吐

4、量降低了。 关 键 词：关 键 词：无线局域网，媒体接入控制，服务质量，增强分布式协调功能 论文类型：论文类型：应用研究 摘要 II Subject: Study on performance of media access control in wireless LANs Specialty: Computer Application Technology Name: Nie shiqun Supervisor: Liu wei ABSTRACT Wireless local area networks (WLANs) have caught considerable attention i

5、n recent years for its advantages, such as flexible mobility, high secrecy, convenient installation and maintenance. As a kind of standard, the IEEE 802.11 WLAN has been accepted and employed around the world. The original IEEE 802.11 standard was basically built to support data applications. But, w

6、ith the demand of multimedia applications in WLANs increasing quickly, it has become an obvious question needed to solve that WLANs needs to support real-time multimedia service, such as voice and video, under better quality of service (QoS) guarantee. Since the medium access technology implemented

7、in medium access control (MAC) sublayer is very important to QoS guarantee, the study of medium access technology in wireless local networks is of very important significance. There are two main kinds of medium access functions, including contention access function and center controlled scheduling f

8、unction. As to this paper, our major study is the contention access function, and that is the distributed coordination function (DCF) and enhanced distributed channel access (EDCA) of WLAN. Based on analyzing the IEEE 802.11 standard and 802.11e standard, we contrasted and analyzed the distributed c

9、oordination function (DCF) and enhanced distributed channel access (EDCA) with different environments of service. Our simulations have verified that the service differentiating capabilities of the EDCA mechanism works under saturated traffic conditions, and it improves the system performance of the

10、throughput and media access delay; we also studied the influence to the throughput and media access delay of WLAN by tuning contention window size and arbitration inter-frame space. The result of simulations shows that arbitration inter- frame space can change media access delay of the traffic, cont

11、ention window can affect the overall system performance. In addition, we have improved analysis model for EDCA under saturated traffic conditions. The model improved can response network conditions more accurately. Furthermore, we focused on the analysis of the 摘要 III system saturated throughput tha

12、t increased TXOP. Finally, simulation results show that under the condition of saturated traffic, the throughput of higher priority traffic is improved, but the throughput of lower priority traffic is reduced, when TXOP is increased. KEY WORDS: wireless local network, media access control, quality o

13、f service, EDCA Dissertation Type: Applicatiopn research 附录 缩略语词汇表缩略语词汇表 IEEE Institute of Electrical and Electronics Engineers 电气和电子工程师协会 WLAN Wireless Local Network 无线局域网 IP International Protocol 国际互联网络通讯协议 QoS Quality of Service 服务质量 MAC Medium Access Control 媒体接入控制 DCF Distributed Control Funct

14、ion 分布式控制功能 CSMA/CA Carrier Sense Multiple Access with Collision Avoidance 带冲突避免的载波侦听多路接入 PCF Point Control Function 点协调功能 HCF Hybrid Control Function 复合控制功能 EDCA Enhanced Distributed Channel Access 增强的分布式信道接入 HCCA HCF Controlled Channel Access 复合的控制信道接入 DSSS Direct Sequence Spread Spectrum 直接序列扩频 O

15、FDM Orthogonal Frequency Division Multiplexing 正交频分复用 MIMO Multiple Input Multiple Output 多输入多输出 VOIP Voice of IP 互联网协议电话 RSVP Resource reservation Protocol 资源预留协议 PLCP Physical Layer Convergence Procedure 物理层汇聚子层 PMD Physical Medium Dependent 物理媒介依赖 LLC Logical Link Control 逻辑链路控制 MSDU MAC Service Data Unit 媒体接入服务数据单元 STA Station