Research Of Passive Measurement In CDMA2000 Core Network

With a substantial growth of 3G user population and traffic volumes carried by 3G network, the problems such as decline in the quality of service, network security issues and so on, will inevitably increase. Therefore, it is compelling for 3G operators to understand and analyse network in-deep in order to discover problems, optimize network configuration and find potential risks may exsist. Network Measurement is one of the most important methods to understand and analyse network.Passive measurement has advantages of few side effects, accurate and comprehensive measurement results and so on. In this thesis we studied related technologies of passive measurement in CDMA2000 core network and measured an operating network. Our works include:Firstly, we proposed an architechture of passive measurement in CDMA2000 core network. After analyzing the protocol stack of interfaces of CDMA2000 core network, we selected the appropriate passive measurement point, and proposed a passive measurement system for CDMA2000 core network.Secondly, PPP de-encapsalation is the key technology of passive measurement in CDMA2000 core network. Against low performance of existing serial PPP de-encapsalation, we presented an idea of multi-bytes (N-bytes) parallel PPP de-encapsalation which takes full advantage of parallelly processing capability of hardware. We implemented 2-Bytes and 4-Bytes software-based and 16-Bytes FPGA-based algorithms. Experiments proved that 4-Bytes software algorithm compared to traditional serial algorithm improves the performance of 50%. The traffic reduction system was implemented based on FPGA algorithms. The N-Bytes algorithms are used not only to reduce traffic in CDMA2000, but also to improve the performance of PPP broadband access severs (eg PPPoE BAS, PDSN) and PPP terminals (eg PC, CDMA modern, CDMA phone).At last, we implemented measurements of round-trip-time, channel rate and packet loss rate in a passive way, measured an operating CDMA2000 network in a province of North China. Measurement results included packet length, TCP option statistics, application protocol statistics, round-trip-time, channel rate and packet loss rate. Some important conclusions were obtaind through the analysis of these results.