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1、中国移动GPRS无线优化课题交流会,Solution Center GTSS China Motorola,1. GPRS业务模型分析,Motorola USTM View of User Services,USTM considers service activity from the GPRS/UMTS users point of view: (USTM stands for Unified Simple Traffic Models),User Application,Telecommunications Network,User Application,Application Lev
2、el Service Activity,At this level the application service behaviour is relatively network implementation independent. However, as the traffic is transported over the network, traffic behaviour within the network will depend on the network implementation and configuration,Example: Application Protoco
3、ls Interaction,As the application interacts with different protocols in the network implementation, application traffic becomes packets.,Application,Application,UMTS Network,UTRAN,Core Network,Internet,TCP/IP,Packet Activity,Application-level Activity,Packet behaviour may be different in different p
4、rotocol layers, and parts of the network, i.e:,UTRAN UMTS Core Network External Packet Data Network,TCP & IP packets RLC SDU Radio frames,Layered Traffic Modelling Approach,The traffic characteristics of a service can be very complex. It is often described by a layered service workload model data ap
5、plication model in USTM. The following is a view of the FTP service:,Session,Burst (File),Packet,t,t,t,Definition of A Session,A service session is a logical entity. Independent of transmission direction. It is basically described as the period where a user is actively using the service. During an a
6、ctive service session, the network must maintain connectivity between the users in that session.,Service Definition of Session Telephony: Telephone call duration WWW: Web browsing session (difficult to determine finish) FTP: Period downloading from single server Email (download): From connecting to
7、email server to disconnection,Sessions are described by: Session Duration (D) Session Inter-arrival time (I),D,I,t,Definition of A Burst,Service Example of Burst Telephony: Active talk spurt WWW: HTTP objects in a WWW page download FTP: Transfer of a file between server client Email (download): A fi
8、le containing single email with MIME encoded attachments SMS: One text message,Bursts described by: Burst Size/Duration () Inter-burst time (T),T,t,The Burst represents a block of real traffic that the application sends/receives. The Burst is the activity that the bearer channels in the network see.
9、 For many services, a burst equates to the transfer of a file or message. The burst is uni-directional (uplink and downlink bursts are different).,Note: Burst duration may be driven by data size/link speed/load,More Examples of Burst,Telephony:,Speech bursts,Uplink,Downlink,WWW:,File bursts,Uplink,D
10、ownlink,Page Downloads,SMS MO:,Message Burst,Uplink,Speech samples encoded into speech frames. Whilst originator is talking, speech frame activity generates the speech burst.,Complex WWW pages may contain multiple objects located on different servers. Downloading an object is an HTTP request/respons
11、e transaction.,Unidirectional transmission of the SMS packet.,A complete View Example: WWW Traffic Model,S,A,WWW Application Summary:,Session,Objects,t,D,I,t,Bursts,t,UL,DL,Burst,Packet,T,D - Session duration I - Session inter-arrival time - Burst duration T - Inter-burst time S - Packet size A - Pa
12、cket inter-arrival time,PDP Contexts,PDP Contexts vs. Sessions in USTM,A service session needs a connection across the IP networks to operate. Thus a service session needs a PDP context over UMTS for its duration. However, a PDP context may exist before and after a particular service session. More t
13、han one service session can use a single PDP context. Different services sessions may share a single PDP context. PDP contexts may change states (active, standby). This is transparent to the service.,Service A sessions,Service B sessions,PDP Contexts,t,Data Collection points,RAN,Core,PDN,Gb,MDTT,PC,
14、tcpdump/windump Tcptrace/Etherreal Netsense,Gi,Gb Consultant,RadCom,Gb Link Analysis,End-to-End Analysis,Performance Benchmarking,End User (Data and RF Stats),K1205,Gb Snoop,GDS,Scripts,BOT,Gi Link Analysis,tcpdump,Windump,Tcptrace,Etherreal,Netsense,TCP Analyzer,TEMS,用户数据流与协议栈,用户数据(IP包)从终端出发跨过GPRS承
15、载到达因特网, 途中进行了大量的协议封装和解封装, 传输完成后, 在GGSN还原成原来的用户数据(IP包), 从GGSN经Gi接口进入因特网, 我们选择Gi接口作为用户数据流的侦听和分析点.,Gi接口用户数据的封装,WAP数据从GGSN出发封装到GRE隧道协议中去WAP网关, WAP网关作为代理访问服务站点 WWW服务,电子邮件服务以及其它因特网服务经过TCP/UDP封装后, 直接进入因特网去服务站点,因特网,GGSN,Wap GW,GRE,TCP/UDP,www server,Other Apps,Mail service,协议栈与分析内容,封装后的应用层报文和实际传输的数据, 如FTP Data,应用层报文(控制消息等), 如FTP Control,在应用层只能看到“应用消息”, 它被封装到传输层和网络层与数据一起被传输, 在应用层的话务量分析没有意义.应用层做会话分析, 传输层做连接分析和话务分析.,分析内容,分析内容,Case Study in 2003 from a European Network,Detailed Analysis General Total Figures,Total Figures All Sessions +10kByte Se
