Research On The Key Technologies Of Quality Of Service In WCDMA Core Networks

mobile communication network. The mobile communication system based on circuit exchange will become an all-IP network consisting of IP core cable network and radio access network. WCDMA is a main standard for the 3G. With the maturity of the radio access technology and the extension of multimedia real-time services, it has been an emphasis to research the QoS mechanism in WCDMA core network for the network designers and service providers.This dissertation centers on"key technology of QoS in the WCDMA core network " In view of the characteristic that the main elements of the WCDMA core network's PS domain all are based on network processor hardware platform, in order to realize DIFFSERV model of WCDMA core network QoS, the dissertation has researched on the network processor parallelism, the network processor programming model, the buffer management algorithm of network processor, the packet scheduling algorithm of network processor, packet classification algorithm of network processor in detail.This dissertation has outlined the advance history of WCDMA network in the introduction. Hardware system structures of GGSN and SGSN have been analyzed which are WCDMA core network nodes. Then the dissertation draw a conclusion that the network processor technology is the key of realization of the core network QoS, simultaneously, the dissertation has summarized the up to date work of WCDMA core network QoS and the network processor research.This dissertation has carried on the thorough analysis of WCDMA core network QoS, through the comparison of traditional DIFFSERV model and INTSERV model, the dissertation has drawn the conclusion that DIFFSERV model is the best model of realization of WCDMA core network QoS.Base on the research of network processor IXP2400's hardware architecture and the hardware parallel characteristic, the programming model which includes Pool of Threads POTs model and Hyper Task Chaining model has been studied thoroughly. By the method of folding, Distribute cache, AISR Array, Inter-Thread-Signaling, we resolve the question of Mutual Exclusion and Packet Ordering that are the difficulties in parallel program.In view of the demand of WCDMA core network DIFFSERV model realization process, the two kind of programming models can be reasonable and flexible map to different QoS control module.Buffer management algorithm, packet scheduling algorithm, packet classification are the key algorithm of network QoS control, currently, the research of these algorithms limit on general processor platform and simulation environment. In order to realize WCDMA core network QoS, It must consider the WCDMA core network PS domain characteristic and the network processor hardware platform characteristic, then present new practical feasible algorithms. This dissertation has carried on some beneficial attempts and the exploration in this direction.Queue management of network processor divides into the buffer management and packet scheduling and separately carries on the discussion. Because of traditional RED drop algorithm is sensitive to parameter, a kind of auto-adapted buffer management algorithm PAFD is proposed in the paper, this algorithm has consider fairness and throughput, it use the smooth buffer taking rate function to adjust parameter, the experiment has proved this algorithm had the smooth flow curve, it has obtained a better tradeoff between fairness and the network throughout. Considering the core network multi-services situation, multi- services support model of PAFD is also provided and realized in the chapter, too.Because of tradition packet-scheduling algorithm does not consider the CPU process cycle, a new packet-scheduling algorithm PWFQ is presented and realized on the ixp2400. This algorithm considers CPU taking rates and the bandwidth taking rates. In order to realize on the network processor platform, the algorithm adapts the compute method of system virtual time, the new compute method enhances the efficiency of the algorithm running on the network processor platform.Although the GPS packet-scheduling algorithm has the very good fairness, its realization is too complex for ixp2400, because the IXP2400 code space is too small to realize the algorithm. In order to get the high code function ratio and obtain high transmits speed, this dissertation also proposed a new packet scheduling algorithm UOWRR which has optimized for the demand of WCDMA core network QoS control. It based on WRR algorithm. UOWRR can satisfy the delay requirements for conversational and stream class, and guarantee the bandwidth for interactive and background class using priority and queue dividing mechanism. This algorithm is especially suitable for the network processor platform.On the fact that the network processor is sensitive to memory visit and high-speed parallelism characteristic, the paper proposed a multi-dimensional packet classification algorithm CBNP. This algorithm base on the dimension compression, and parallel carries on Tuple space to search, it effectively reduced the memory access and the storage space and provided a better time and space complexity.The dissertation has also designed a practice DIFFSERV model scheme for WCDMA core network QoS control. The scheme integrates the entire algorithm that is discussed in the paper and gets ideal effect in practice.