Analysis of cellular CDMA systems with adaptive modulation scheme

number: 
1764
English
Degree: 
Author: 
Faris Abdul-Razzaq Ajeel
Supervisor: 
Dr. Raad Sami Fyath
year: 
2006
Abstract:

Wireless communications start to make large steps in developments especially through the last decade along with the large growth in digital integrated circuit “IC” fabrication and radio frequency circuitry. Digital switching techniques simplify the use of wireless communication networks. The multiple access techniques like FDMA, TDMA and CDMA play a major role in the growth of wireless communication and wireless systems. The work in this thesis is based on CDMA as a multiple access technique between the different users. This technique is useful to propose a digital wireless system design that is flexible and may upgraded later based on the basic system design but only with slight changes. The average bit error rate (BER) and bits per symbol (BPS) performance of CDMA system adopting adaptive modulation scheme (AMS) are evaluated in the forward link. The evaluation is carried out on the level of the cell based on the estimation of the received signal-to-noise ratio (SNR) by the mobile station located at arbitrary cell position, and after the mobile station sent information back to the base station about the environment state. The base station transceiver can select the modulation mode that is the most suitable to the current channel state. The base station then sends information again to the mobile station using the selected modulation scheme. Several case studies are presented to check the system compatibility and to reduce the problems that may occur leading the way for future system hardware construction. MATLAB simulation results are presented for AMSCDMA system incorporating BPSK, 4QAM, 16QAM, and 64QAM modulation schemes.