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Performance modeling of the contention-based reservation protocol in the general packet radio service (GPRS)/enhanced GPRS (EGPRS) under bursty traffic is of practical use in system design. Instead of using discrete event simulation, we construct an analytical model based on stochastic Petri net formalism to investigate GPRS uplink performance efficiently. The model is built to capture the major features of a realistic system, taking into account factors such as the traffic profile, the system's capture capability, the contention persistence, the multislot capability, and the use of the access queue and the round-robin virtual serving queue. As shown in numerical results, these factors have different impacts on the performance measures, such as link-control-layer frame-blocking probability, frame delay, system throughput, and packet-channel utilization. To avoid modeling and computational complexity in a GPRS/EGPRS system model that supports several mobile terminals, we make first-order approximations and use an iterative fixed-point scheme. Comparisons with discrete event simulations are conducted and show promising agreement with the proposed analytical-numerical model. We then use the model to investigate GPRS packet-data performance under different parameter settings and present numerical results, providing insights into network design and optimization.
Date of Publication: Nov. 2003