Abstract:
This thesis work is concerned with the performance analysis of slotted Aloha based
various generations cellular access networks such as GSM (2G), GPRS (2G+) and
WCDMA (3G). Slotted Aloha is the most primary and simplest protocol for uplink
access technique. In this work computer simulation. is carried. out to study the
channel behavior of a slotted Aloha based random access channel employing
diffcrcnt performancc optimization schcmes to improve the stability, carrier sensing
capability, collision detection techniques and capacity etc. of such a system. The
combined effcCt of capture and retransmission algorithm on the stability and all
various quality parameters, such as system throughput, maximum allowable new and
gross traFfic, access delay, rejection probability etc. have been formulatcd in this
work. Optimum values of different system parameters for a slotted Aloha based
random access scheme have been determined .Various performance improvement
techniques are also analyzed to find the optimum QoS parameters by maintaining a
stable radio access system. Different network parameters are also evaluated for both
finite and infinite users cases. The impact of the number of RACH (Random Access
Channel) slots has been analyzed on the performance of the GSM systems both in a
low-capture and in no-capture environment. It has also been found that the
performance in a low-capture environment is better than no-capture environment for
both the GSM and GPRS standards. Further stable operation of random access
procedure are also analyzed in a multi service based 3G WCDMA system. Suitable
and appropriate power control schemes, power ramping, ramping steps, capture
environment, signature choice procedures are chosen for different traffic classes to
enhance the system performance. Various values of RACH (Random Access
Channel) parameters are used for real and non-real time services to optimize the
utilization of radio resource as well as to keep the system stable and appropriate
RACH parameters are evaluated and the mechanism of controlling access load has
been discussed considering finite and infinite users.
