GPRS数据传输优化策略的研究和实现
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摘要
本文的目的是建立一个在GPRS通讯网络中的数据压缩模型。GPRS网络中无线信道的带宽是整个通信系统中最宝贵的资源。然而,由于层次性互联网传输协议框架中各层协议的封装,协议报头变得越来越大,且越来越复杂,相当一部分无线带宽用来传送控制信息(即协议报头),而这些控制信息对终端用户有太多的冗余信息,这样导致了无线信道带宽的利用率较低。
本文首先对当前数据压缩理论和国内外研究现状进行了较为深入的分析,采用3GPP的数据压缩模型来构造数据压缩系统。3GPP的数据压缩模型主要通过IP数据报头复用和RTP报头压缩达到缩减数据量的目的。IP数据报头复用技术使得同一IP Flow的IP数据包共享IP数据报头部分,构造数据大包,可以有效降低IP数据报头数据所占的比重。RTP报头压缩提取关键的时间戳信息和序列号信息,构造只有三个字节的RTP报头,可以有效降低通信数据量。
本文的主要贡献是在IS RackServer平台上面构造一个在GPRS网络中能够稳定运营的通信数据压缩系统,着重描述了数据压缩系统的解决方案和实现过程。本文接着描述了系统的总体设计、具体实现和实验结果。本系统首先利用开源PF_RING模块构造大容量数据包的收发平台,使得Linux操作系统可以收发大容量的数据包,PF_RING模块直接在网卡上面捕获数据包并且根据数据包的类型转发到相应的处理模块。针对原始的IP数据包,本系统首先进行IP报头复用处理然后再进行RTP报头压缩处理最后转发到目的地。针对已经压缩好的IP数据包,本系统首先进行RTP报头解压缩处理然后进行IP报头解复用处理,最后转发到MGW。实验结果表明本系统可以节约30%的通信带宽,并且可以稳定可靠地运行。
This thesis intends to build robust solution for GPRS network to save the bandwidth, which is the most precious resource in telecommunication network. Most of GPRS data is carried by RTP/UDP/IP packets which include long header field. The encapsulation process of the hierarchical transmission protocols wastes a substantial part of the wireless bandwidth for the transmission of control information (header) that does not have any specific function for the management of wireless channel itself.
Based on the data compression theory and the current research result, this thesis adopts the 3GPP bandwidth saving model to develop a solid data compression system for GPRS network. 3GPP bandwidth saving model uses IP header multiplex and RTP header compression to reduce the traffic data. IP header multiplex will merge the IP packets which have the same source IP. address and the same destination IP address into a larger IP packet. This method can notably reduce the IP header information. RTP header compression uses the key RTP timestamp data and RTP sequence number data to build a compressed RTP header which only consumes 3 bytes.
This thesis describes the development of the bandwidth saving system. The thesis demonstrates the high level design and the module design of bandwidth saving system and finally describes the test result. The system uses PF_RING open source module to build the data packet transportation platform to capture high load data traffic. PF_RING will capture the data packets at the network interface card directly and dispatch the packets to handling module according data packet type. For the raw IP packets, the system will do the IP header multiplex and RTP header compression. For the multiplexed IP packets, the system will deconstruct the IP packets and do RTP header decompression to rebuild the raw IP packet. It is shown in the test result that the traffic data can reduce by 30% and this system has a reliable performance.
本文首先对当前数据压缩理论和国内外研究现状进行了较为深入的分析,采用3GPP的数据压缩模型来构造数据压缩系统。3GPP的数据压缩模型主要通过IP数据报头复用和RTP报头压缩达到缩减数据量的目的。IP数据报头复用技术使得同一IP Flow的IP数据包共享IP数据报头部分,构造数据大包,可以有效降低IP数据报头数据所占的比重。RTP报头压缩提取关键的时间戳信息和序列号信息,构造只有三个字节的RTP报头,可以有效降低通信数据量。
本文的主要贡献是在IS RackServer平台上面构造一个在GPRS网络中能够稳定运营的通信数据压缩系统,着重描述了数据压缩系统的解决方案和实现过程。本文接着描述了系统的总体设计、具体实现和实验结果。本系统首先利用开源PF_RING模块构造大容量数据包的收发平台,使得Linux操作系统可以收发大容量的数据包,PF_RING模块直接在网卡上面捕获数据包并且根据数据包的类型转发到相应的处理模块。针对原始的IP数据包,本系统首先进行IP报头复用处理然后再进行RTP报头压缩处理最后转发到目的地。针对已经压缩好的IP数据包,本系统首先进行RTP报头解压缩处理然后进行IP报头解复用处理,最后转发到MGW。实验结果表明本系统可以节约30%的通信带宽,并且可以稳定可靠地运行。
This thesis intends to build robust solution for GPRS network to save the bandwidth, which is the most precious resource in telecommunication network. Most of GPRS data is carried by RTP/UDP/IP packets which include long header field. The encapsulation process of the hierarchical transmission protocols wastes a substantial part of the wireless bandwidth for the transmission of control information (header) that does not have any specific function for the management of wireless channel itself.
Based on the data compression theory and the current research result, this thesis adopts the 3GPP bandwidth saving model to develop a solid data compression system for GPRS network. 3GPP bandwidth saving model uses IP header multiplex and RTP header compression to reduce the traffic data. IP header multiplex will merge the IP packets which have the same source IP. address and the same destination IP address into a larger IP packet. This method can notably reduce the IP header information. RTP header compression uses the key RTP timestamp data and RTP sequence number data to build a compressed RTP header which only consumes 3 bytes.
This thesis describes the development of the bandwidth saving system. The thesis demonstrates the high level design and the module design of bandwidth saving system and finally describes the test result. The system uses PF_RING open source module to build the data packet transportation platform to capture high load data traffic. PF_RING will capture the data packets at the network interface card directly and dispatch the packets to handling module according data packet type. For the raw IP packets, the system will do the IP header multiplex and RTP header compression. For the multiplexed IP packets, the system will deconstruct the IP packets and do RTP header decompression to rebuild the raw IP packet. It is shown in the test result that the traffic data can reduce by 30% and this system has a reliable performance.
引文
铩颷1]蒋文怡,李红君,GPRS通用分组无线业务,人民邮电出版社 2001
[2]韩斌杰,《GPRS原理及其网络优化》,机械工业出版社,2003.
[3]通用分组无线业务(GPRS)的技术实现和业务应用的研究,信息产业部电信传输研究所, 1996.6
[4]钟章队,GPRS通用分组无线技术,北京,人民邮电出版社,2000
[5]GSM 04.60(Phase2+);General Packet Radio Service(GPRS);Mobile station(MS)-Base Station System(BSS)interface;Radio Link Control/Medium Access Control(RLC/MAC) protocol
[6]3GP PTS 23.060:General Packet Radio Service(GPRS)Service description
[7]赵长奎 GSM数字移动通信应用系统,国防工业出版社,2001
[8]杨筱凡,曹鹏,蔡斌,黄载禄.GPRS骨干网内移动终端间路由的优化方案.通信学报. 2003(24),5:72-78
[9]计算机网络(第四版)S.Tanenbaum清华大学出版社,2004
[10]C.Perkins.IP Mobility Support.RFC 3220.January 2002
[11]551 Charles E.Perkins.Mobile IPv6 for 3G Telephony.presentations in China IPv6 Workshop 2001.May,2001
[12]V Jacobson,“Compressing TCP/IP Headers for Low-speed Serial Links, Request for Comments 1144,”February 1990
[13]徐士良《计算机常用算法》清华大学出版社,2003
[14]算法设计John Kleinberg,Eva Tardos清华大学出版社,2004
[15]Mika Isosaari Bandwidth Saving Solutions in Nb Interface for IP Traffic Ericsson Internal material
[16]L-E.Jonsson,Robust Header Compression(ROHC):Requiremonts and Assumptions for O-byte IP/UDP/RTP Compression,RFC3243,April 2002
[17]Carsten Borman,Robust Header Compression(ROHC)-A step towards all IP wireless networks,TZI,2001
[18]3GP PTS29.414 Technical Specification Group Core Network and Terminals; Core network Nb data transport and transport signaling
[19]M.Degermark,Requirements for robust IP/UDP/RTP header compression, RFC3096,July 2001
[20]3rd Generation Partnership Project,“Radio Access Bearer Support Enhancements”2002.
[2]韩斌杰,《GPRS原理及其网络优化》,机械工业出版社,2003.
[3]通用分组无线业务(GPRS)的技术实现和业务应用的研究,信息产业部电信传输研究所, 1996.6
[4]钟章队,GPRS通用分组无线技术,北京,人民邮电出版社,2000
[5]GSM 04.60(Phase2+);General Packet Radio Service(GPRS);Mobile station(MS)-Base Station System(BSS)interface;Radio Link Control/Medium Access Control(RLC/MAC) protocol
[6]3GP PTS 23.060:General Packet Radio Service(GPRS)Service description
[7]赵长奎 GSM数字移动通信应用系统,国防工业出版社,2001
[8]杨筱凡,曹鹏,蔡斌,黄载禄.GPRS骨干网内移动终端间路由的优化方案.通信学报. 2003(24),5:72-78
[9]计算机网络(第四版)S.Tanenbaum清华大学出版社,2004
[10]C.Perkins.IP Mobility Support.RFC 3220.January 2002
[11]551 Charles E.Perkins.Mobile IPv6 for 3G Telephony.presentations in China IPv6 Workshop 2001.May,2001
[12]V Jacobson,“Compressing TCP/IP Headers for Low-speed Serial Links, Request for Comments 1144,”February 1990
[13]徐士良《计算机常用算法》清华大学出版社,2003
[14]算法设计John Kleinberg,Eva Tardos清华大学出版社,2004
[15]Mika Isosaari Bandwidth Saving Solutions in Nb Interface for IP Traffic Ericsson Internal material
[16]L-E.Jonsson,Robust Header Compression(ROHC):Requiremonts and Assumptions for O-byte IP/UDP/RTP Compression,RFC3243,April 2002
[17]Carsten Borman,Robust Header Compression(ROHC)-A step towards all IP wireless networks,TZI,2001
[18]3GP PTS29.414 Technical Specification Group Core Network and Terminals; Core network Nb data transport and transport signaling
[19]M.Degermark,Requirements for robust IP/UDP/RTP header compression, RFC3096,July 2001
[20]3rd Generation Partnership Project,“Radio Access Bearer Support Enhancements”2002.