VoWLAN的QoS优化和漫游切换研究
摘要
近年来,随着网络电话(VoIP)技术的快速发展,用户要求体验无线连接性所带来的便利,无线网络电话(VoWLAN)应运而生。VoWLAN将价格低廉的VoIP技术与灵活的无线技术相结合,成为传统蜂窝电话以及有线VoIP电话的强有力竞争对手。但是在实际应用中,VoWLAN技术还存在两个主要障碍：服务质量(QoS)和漫游切换问题。为此,本文从以下两个方面展开了研究：
针对VoWLAN的QoS问题,分析了具体的VoWLAN网络对QoS的要求,研究了经典的VoWLAN的QoS优化方案EDCF(增强的分布式协调功能)机制和AEDCF(自适应EDCF)机制,了解了各种机制的优点和不足。在此基础上,提出一种新的基于EDCF的改进算法NEDCF,利用冲突率因子和网络阈值来划分网络状态,各网络状态采用不同的竞争窗口(CW)参数调整机制及相关退避算法。最后对NEDCF进行了仿真模拟,结果表明,NEDCF能有效改善延迟、丢包和抖动,提高了VoWLAN的服务质量。
针对VoWLAN的漫游切换问题,分析了VoWLAN漫游过程,研究了经典的VoWLAN的漫游切换优化方案802.11f机制、802.11r机制、Mobile IP机制和Mobile SIP机制,比较了各种机制的优缺点。针对现有漫游切换方案时延过长的问题,提出了一种改进的漫游时延优化方案FROAM,除了将802.11r和Mobile SIP机制有机结合外,增加一个漫游模式判断服务器,使得可以分别处理子网间漫游和域间漫游,并把域问漫游中的SIP协议信令控制过程提前到链路切换之前,减少了漫游切换时间,提高了漫游切换性能。
Recently,with the fast development of VoIP,users want to experience connectivity brought by the wireless,so VoWLAN appears. The low price VoIP technology and the flexible wireless technology are conbined by VoWLAN,it becomes a strong rival with traditional cellular phones and cable VoIP phones. However, in practical applications, there are two major obstacles in VoWLAN:quality of service and roaming switch.Therefore,this paper expands the research following the two aspects as below:
To solve the problem of VoWLAN QoS, the paper has analysed QoS of the specific VoWLAN network,studied classical optimum schemes EDCF and AEDCF mechanism for VoWLAN QoS, learnt the strengths and weaknesses of the mechanisms. On this basis, this paper proposes a new algorithm NEDCF which is based on the improvement of the EDCF, NEDCF uses network conflict rate and threshold to divide network state,then makes different network state with different CW and retreated algorithm. At last,there are simulations for NEDCF, simulations show that NEDCF algorithm can improve the delay, packet loss and jitter effectively, thus improving the performance of VoWLAN.
To solve the problem of VoWLAN roaming switch,the paper has analysed the VoWLAN roaming process,studied classical optimum schemes 802.11 f, 802.11r, Mobile IP and Mobile SIP mechanism for VoWLAN roaming switch, learnt the strengths and weaknesses of the mechanisms. For the question of long time roaming switch,this paper proposes a improved mechanism FROAM, which combines 802.11r and Mobile SIP,and adds a roaming mode judging server. FROAM can handle subnetwork interconnection roaming and domain roaming respectively. Furthermore, FROAM makes SIP signaling control process ahead of the link switch process. Thus froam can reduce the delay greatly and improve the performance of VoWLAN roaming switch.
针对VoWLAN的QoS问题,分析了具体的VoWLAN网络对QoS的要求,研究了经典的VoWLAN的QoS优化方案EDCF(增强的分布式协调功能)机制和AEDCF(自适应EDCF)机制,了解了各种机制的优点和不足。在此基础上,提出一种新的基于EDCF的改进算法NEDCF,利用冲突率因子和网络阈值来划分网络状态,各网络状态采用不同的竞争窗口(CW)参数调整机制及相关退避算法。最后对NEDCF进行了仿真模拟,结果表明,NEDCF能有效改善延迟、丢包和抖动,提高了VoWLAN的服务质量。
针对VoWLAN的漫游切换问题,分析了VoWLAN漫游过程,研究了经典的VoWLAN的漫游切换优化方案802.11f机制、802.11r机制、Mobile IP机制和Mobile SIP机制,比较了各种机制的优缺点。针对现有漫游切换方案时延过长的问题,提出了一种改进的漫游时延优化方案FROAM,除了将802.11r和Mobile SIP机制有机结合外,增加一个漫游模式判断服务器,使得可以分别处理子网间漫游和域间漫游,并把域问漫游中的SIP协议信令控制过程提前到链路切换之前,减少了漫游切换时间,提高了漫游切换性能。
Recently,with the fast development of VoIP,users want to experience connectivity brought by the wireless,so VoWLAN appears. The low price VoIP technology and the flexible wireless technology are conbined by VoWLAN,it becomes a strong rival with traditional cellular phones and cable VoIP phones. However, in practical applications, there are two major obstacles in VoWLAN:quality of service and roaming switch.Therefore,this paper expands the research following the two aspects as below:
To solve the problem of VoWLAN QoS, the paper has analysed QoS of the specific VoWLAN network,studied classical optimum schemes EDCF and AEDCF mechanism for VoWLAN QoS, learnt the strengths and weaknesses of the mechanisms. On this basis, this paper proposes a new algorithm NEDCF which is based on the improvement of the EDCF, NEDCF uses network conflict rate and threshold to divide network state,then makes different network state with different CW and retreated algorithm. At last,there are simulations for NEDCF, simulations show that NEDCF algorithm can improve the delay, packet loss and jitter effectively, thus improving the performance of VoWLAN.
To solve the problem of VoWLAN roaming switch,the paper has analysed the VoWLAN roaming process,studied classical optimum schemes 802.11 f, 802.11r, Mobile IP and Mobile SIP mechanism for VoWLAN roaming switch, learnt the strengths and weaknesses of the mechanisms. For the question of long time roaming switch,this paper proposes a improved mechanism FROAM, which combines 802.11r and Mobile SIP,and adds a roaming mode judging server. FROAM can handle subnetwork interconnection roaming and domain roaming respectively. Furthermore, FROAM makes SIP signaling control process ahead of the link switch process. Thus froam can reduce the delay greatly and improve the performance of VoWLAN roaming switch.
引文
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[5]Howon Lee. Capacity Improvement and Analysis of VoIP Service in a Cognitive Radio System. IEEE Transactions on Vehicular Technology,2010.1646-1651
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[11]龙昭华.一种保障VoIP QoS的集成模型及其改进策略研究.计算机科学,2004,31(9)：50-54
[12]Hongqiang Zhai, Yuguang Fang. Performance of Wireless LANs Based on IEEE 802.11 MAC Protocols. IEEE International Symposium on Personal Indoor and Mobile Radio Communication Proceedings,2003.2586-2590
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[38]刘浩.基于RTP/RTCP协议的IP视频系统设计与实现.计算机应用研究,2002,19(10)：140-143
[39]刘坚.基于MPEG-4和RTP的视频监控系统的研究：[硕士学位论文].上海：上海交通大学.2005
[40]杜忠燕.SIP的VoWLAN通信平台设计与实现.计算机应用,2010,2：312-315
[41]乔荔VoWLAN企业级应用模式及解决方案.中兴通讯技术,2007,13(6)：51-53
[42]周雪莉.无线局域网上VoIP传输的性能分析与仿真研究：[硕士学位论文].南京：东南大学,2004
[43]杨丹.无线局域网VoIP传输性能分析与研究：[硕士学位论文].南京：东南大学,2007
[44]王少华VoWLAN技术：现状及挑战.数字通信世界,2008,3：54-57
[45]Jie Li, Qi-Fan Cui.The QoS Research of VoIP over WLAN. IEEE Network,2006(3)：1782-1785
[46]万东辉.基于区分服务和变速率编码的VoIP QoS研究：[硕士学位论文].苏州：苏州大学,2005
[47]周婷.无线局域网的VoIP QoS研究：[硕士学位论文].长沙：中南大学,2007
[48]严少虎.IEEE802.11 DCF发送过程的能耗分析.电子与信息学报,2004,26(7)：1107-1113
[49]熊旭辉,余胜生.支持QoS的IEEE802.11的分布协调功能(DCF)算法.小型微型计算机系统,2003,24(12)：2128-2131
[50]G. Bianchi.Performance Analysis of the IEEE 802.11 Distributed Coordination Function. IEEE JSAC.2000,3:535-547
[51]Yang Xiao. Performance Analysis of Priority Schemes for IEEE802.11 and IEEE802. 11e Wireless LANs. IEEE Transactions on Wireless Communications, 2005.1506-1515
[52]I. Aad, and C. Castellucca. Differentiation Mechanisms for IEEE802.11. IEEE INFOCOM, Anchorage, AK,2001.103-106
[53]Y. Xiao. IEEE 802. 11e:QoS provisioning at the MAC layer. IEEE Wireless Communications'04,2004.72-79
[54]Qing Ni, Performance Analysis and Enhancements for IEEE 802. 11e Wireless Networks. IEEE Network,2005,19(4):21-27
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[2]熊婉VoWLAN:实现语音与数据的彻底融合.中国数据通信,2004,6(7)：17-19
[3]David Geer. The Future of Mobile VoIP in the Enterprise. IEEE Computer Society,2009.15-18
[4]何成勇.VoWLAN技术中若干问题探讨.电信快报：网络与通信,2007,12：27-29
[5]Howon Lee. Capacity Improvement and Analysis of VoIP Service in a Cognitive Radio System. IEEE Transactions on Vehicular Technology,2010.1646-1651
[6]龙国栋.基于SIP的VoWLAN漫游时延优化技术研究：[硕士学位论文].长沙：国防科学技术大学,2008
[7]QoS Manager技术白皮书.http://www.huawei.com/cn/products/datacomm/pdf/ view. do?f=265
[8]孟庆红.QoS技术在IP网络中的应用浅谈.通信与信息技术,2006,6：52-58
[9]刘宴兵.无线网络接入算法及QoS分析研究：[硕士学位论文].成都：电子科技大学,2007
[10]王正要.基于无线局域网络VoIP的QoS机制研究：[硕士学位论文].南京：南京邮电大学,2009
[11]龙昭华.一种保障VoIP QoS的集成模型及其改进策略研究.计算机科学,2004,31(9)：50-54
[12]Hongqiang Zhai, Yuguang Fang. Performance of Wireless LANs Based on IEEE 802.11 MAC Protocols. IEEE International Symposium on Personal Indoor and Mobile Radio Communication Proceedings,2003.2586-2590
[13]HuaZhu. MingLi. A Survey of Quality of Service in IEEE 802.11 Networks. IEEE Wireless Communications,2004.6-14
[14]S. Mangold. IEEE 802. 11e Wireless LAN for Quality of Service. European Wireless,2002.167-172
[15]Lamia Romdhani. Adaptive EDCF: Enhanced Service Differentiation for IEEE802.11 Wireless Ad Hoc Networks. IEEE 2003.2956-2961
[16]刘春.基于IP的WLAN快速移动性分析.广西通信技术,2005,3：24-27
[17]O'Hara, Petrick. IEEE 802.11F Inter Access Point Protocol (IAPP). IEEE 802.11 Handbook:A Designer's Companion,2005.217-219
[18]周克琴,李小光.无线局域网的IAPP协议.广东通信技术,2005,25(7)：42-46
[19]李浩.IEEE 802.11无线局域网标准研究.计算机应用研究,2009,5：1616-1620
[20]Hassan Ahmed, Hossam Hassanein. A Performance Study of Roaming in Wireless Local Area Networks Based on IEEE 802. 11r. IEEE 24th Biennial Symposium on Communications,2008.1754-1758
[21]焦燕鸿,侯自强.Mobile SIP与Mobile IP的比较研究.中国通信学会信息通信网络技术委员会2003年年会论文集,2003：N0.101
[22]刘乃安.无线局域网(WLAN)原理、技术与应用.西安：西安电子科技大学出版社,2004.60-63
[23]熊桂喜,王小虎.计算机网络(第3版).北京：清华大学出版社,2000.22-25
[24]汪广洪.IEEE 802.11无线局域网MAC层性能及服务质量研究：[硕士学位论文].天津：天津大学,2004
[25]Inwhee Joe. Reservation CSMA/CA for Multimedia Traffic over Mobile Ad-hoc Networks. IEEE International Conference on Communications,2000.1714-1718
[26]于桦.浅谈IEEE802在现代局域网中的应用.长春大学学报,1999,9(6)：22-23
[27]陈同姓.基于IEEE802.11无线局域网的研究.中国新技术新产品,2010,14：41-42
[28]朱海毅VoIP基本原理.信息技术,2003,27(5)：83-84
[29]Mousa ALAkhras. Voice over IP (VoIP).Communications, Computers and Applications,2008.1-4
[30]于波.VoIP技术原理及展望.电子元器件应用,2006,8(6)：42-44
[31]祝丽丽.VoIP在无线局域网上的应用.广西通信技术,2007,2：14-16
[32]何志斌.基于SSL VPN的SIP网络电话的研究：[硕士学位论文].长沙：中南大学,2008
[33]Schulzrinne H, Rosenberg J.The Session Initiation Protocol:Internet Centric Signaling. IEEE Communication Magazine,2000.134-141
[34]张智江,张云勇.SIP协议及其应用.北京：电子工业出版社,2005
[35]J. Rosenberg. SIP:Session Initiation Protocol. Internet Engineering Task Force, RFC3261,2007
[36]孔令旭,梁福元VoIP技术与网络通讯.信息技术与信息化,2010,1：32-35
[37]杨仁忠,孙国滨.基于IEEE 802.11无线局域网的VoIP技术综述.计算机工程,2005,31(4)：1-3
[38]刘浩.基于RTP/RTCP协议的IP视频系统设计与实现.计算机应用研究,2002,19(10)：140-143
[39]刘坚.基于MPEG-4和RTP的视频监控系统的研究：[硕士学位论文].上海：上海交通大学.2005
[40]杜忠燕.SIP的VoWLAN通信平台设计与实现.计算机应用,2010,2：312-315
[41]乔荔VoWLAN企业级应用模式及解决方案.中兴通讯技术,2007,13(6)：51-53
[42]周雪莉.无线局域网上VoIP传输的性能分析与仿真研究：[硕士学位论文].南京：东南大学,2004
[43]杨丹.无线局域网VoIP传输性能分析与研究：[硕士学位论文].南京：东南大学,2007
[44]王少华VoWLAN技术：现状及挑战.数字通信世界,2008,3：54-57
[45]Jie Li, Qi-Fan Cui.The QoS Research of VoIP over WLAN. IEEE Network,2006(3)：1782-1785
[46]万东辉.基于区分服务和变速率编码的VoIP QoS研究：[硕士学位论文].苏州：苏州大学,2005
[47]周婷.无线局域网的VoIP QoS研究：[硕士学位论文].长沙：中南大学,2007
[48]严少虎.IEEE802.11 DCF发送过程的能耗分析.电子与信息学报,2004,26(7)：1107-1113
[49]熊旭辉,余胜生.支持QoS的IEEE802.11的分布协调功能(DCF)算法.小型微型计算机系统,2003,24(12)：2128-2131
[50]G. Bianchi.Performance Analysis of the IEEE 802.11 Distributed Coordination Function. IEEE JSAC.2000,3:535-547
[51]Yang Xiao. Performance Analysis of Priority Schemes for IEEE802.11 and IEEE802. 11e Wireless LANs. IEEE Transactions on Wireless Communications, 2005.1506-1515
[52]I. Aad, and C. Castellucca. Differentiation Mechanisms for IEEE802.11. IEEE INFOCOM, Anchorage, AK,2001.103-106
[53]Y. Xiao. IEEE 802. 11e:QoS provisioning at the MAC layer. IEEE Wireless Communications'04,2004.72-79
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