Analysis of a traffic model for GSM/GPRS

A traffic model for GSM/GPRS, the hybrid radio resource allocation (HRRA) algorithm is evaluated. A dedicated number of GPRS channels plus idle periods between voice calls are used for GPRS data packet transfers. A simulator was developed in order to evaluate the HRRA algorithm, which provides a reasonable forecast on the voice blocking probability and on packet delay for a single cell system. Since the major issue is the correct resource allocation, results are shown for the influence of some choices and assumptions on the overall system performance. As expected, blocking probability can reach very high values if the number of dedicated channels increases too much. For the specific case of 4 carriers and traffic of 20 Erl, 4 channels dedicated to GPRS still enable an affordable blocking probability, leading to a mean packet delay of 15 s. The results can be used to illustrate the fundamental options that need to be taken by an operator, when implementing GPRS.