Performance analysis of slotted aloha based general packet radio service system for voice and data integrated transmission

Abstract

General packet radio service (GPRS) is designed for transmitting packet data and take its radio resource from the pool of channels unused by global system for mobile (GSM) voice services. Two basic types of channels called random access channel (RACH) and traffic channels (TCH) are used in the uplink direction of the GSM. In this thesis the impact of RACH slots on probability of success, channel utilization and aggregate traffic is analyzed in the first portion and then an analytical model is developed in choosing the appropriate data and voice channel sharing techniques. In the first portion, the impact of RACH slots in a slotted ALOHA based GSM access network is analyzed for different traffic cases. The relation between the probability of success and the number of RACH slots per time unit is evaluated. The traffic channel utilization rate for varying channel holding time and the access throughput for different RACH slots are described. For different probability of success, the total network load is evaluated for the same new packet generation rate. The optimized relation between the total access load and the new arrival rate for different RACH slots is presented which can be utilized in the design of access part of the GSM network to overcome the RACH congestion. In the later part the impact of traffic in a GPRS network is analyzed for different sharing techniques. Blocking probability, throughput, average delay and utilization is calculated for these cases. Then a comparative study and impact of traffic and data channel is performed in different sharing cases. In this thesis it is proposed to design the network in such a way so that it can provide the option to dynamically change the sharing strategy from one to another. The network will allocate the fixed number of data channel according to the need. Comparison with the simulation result is shown in the later section. Then the convergence of fixed and complete sharing into partial sharing is shown. So, the partial sharing is the ultimate solution.