Optimizing the Use of Random Access Channels in GSM-GPRS

The random access channels and traffic channels are utilized, respectively, for call establishment and information transmission in the uplink direction (from mobile to base station) of the Global System for Mobile communications (GSM) networks. A call is either rejected or blocked depending on its inability to succeed either in the random access channels or in the traffic channels. The optimum number of random access slots is directly proportional to the average call arrival rate, being independent of the average channel holding time and the number of traffic channels. The number of slots occupied by a given call can be changed dynamically in the newly developed General Packet Radio Service (GPRS) systems. A complete analysis is executed for the traffic channel utilization and call blocking probability with the exact number of random access slots that provide almost zero call rejection probability. The overall call success probability is derived considering call rejection and call blocking probabilities.