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.
