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.