Real-time performance analysis of wireless multimedia networks based on partially observed, multivariate point processes

Abstract

Third-generation (3G) wireless networks will support integrated multimedia services based on a cellular extension of a packet-switched architecture using variants of the Internet protocol (IP). Services can be categorized as real-time and delaysensitive, or non-real-time and delay-insensitive. Each call, arriving to or active within the network, carries demand for one or more services in parallel; each service type with a guaranteed quality of service (QoS). Admission of new calls to the wireless IP network (WIN) from the gateway of a wired network or from a mobile subscriber (MS) is allowed by call admission control (CAC) procedures. Roaming of the MSs among the nodes of the WIN is controlled by handoff procedures between base stations (BSs), or BS controllers (BSCs), and the MSs. Metrics such as the probabilities of call blocking and dropping, handoff transition time, processing latency of a call, throughput, and capacity are used to evaluate the performance of network control procedures. The metrics are directly related to the network resources required to provide the QoS for the integrated services. User mobility, combined with the "bursty" nature of service demands, leads to transient random behavior of the multiple packet flows for integrated services within the WIN. This paper proposes general stochastic models, based on the theory of multivariate point processes (MVPPs) and their representation as semimartingales, to describe the finitehorizon, transient behavior of the packet flows created by integrated multimedia traffic. The point process corresponding to the packet flow of each service type is decomposed into a right-continuous, pure jump process and a predictable, integrated random rate process. The approach leads to predictive models of information flows that can incorporate the measurementbased estimates of probability distributions for voice, video, data, and Internet traffic, as well as the protocol mechanisms for access, routing and switching in wired networks and for blocking, handoff and radio connectivity in the WIN. The effects of CAC and handoff control are also shown in the terms of the integrated random rates for the information flows. Performance metrics and QoS parameters of multimedia services are represented in the MVPP models. Use of the models to develop stochastic filters of the network state, based on partial or incomplete observations of packet flow dynamics, is presented.