A study and analysis of fading in GSM mobile channel

Dissertant

Salim, Ala Adnan

Thesis advisor

al-Samari, Ayid Khalaf

University

University of Technology

Faculty

-

Department

Department of Electrical Engineering

University Country

Iraq

Degree

Master

Degree Date

2013

English Abstract

The wireless communication system has witnessed a huge growth in different daily life applications in comparison with other communication systems.

As more demands on wireless systems are increasing every day, system designers are forced to raise the bar and come up with more sophisticated designs that provide stable performance in a hostile wireless environment.

In addition, the design must be studied carefully in order to avoid any negative effect on the quality of service.

One of the most important phenomenon that affect the transmitted signal in a wireless channel is a multipath fading.

This thesis studies the effect of multipath propagation fading on the GMSK modulation, which is widely used in the mobile communication systems Such as GSM.

Computer simulations were carried out for multiple mathematical models in an attempt to describe the channel (such as Rayleigh channel, Rician channel, .....etc) behavior statistically Computer simulations were also performed to estimate the improvement in GMSK performance when a diversity combining receiver is used, the simulations are performed for the MRC and the EGC combining techniques at different types of channel.

In this domain the results show a significant improvement in the performance as the diversity order is increased and low bit error rates are achieved at low signal to noise ratio compared to a single channel receiver.

The performance of GMSK is compared to the performances of the BPSK and the QPSK at a range of average signal to noise ratio from (0dB to 30 dB) in such fading channels, the results show that the GMSK has closer performance to the QPSK rather than to the BPSK.

The results show a variation in the communication system performance expressed in terms of the average bit error rate (BER) versus the average of signal to noise ratio (SNR) at different channel models.

For Rayleigh channel and with the use of a single channel receiver simulations show that GMSK was unable to pass the (10-3) bit error rate barrier which is still acceptable in mobile applications but with the use of MRC and EGC techniques the system started to achieve lower bit error rates as the diversity order reached (6) the system was able to achieve average BER (10-7) at (12dB) for MRC and at (15dB) for EGC For the Rician channel when GMSK is evaluated as a single channel receiver results showed that the performance depends on the (K) factor which represents the ratio of the Line of site component to the other multipath components , as the K factor is increased the system performance is improved, the system was able to achieve average BER of (10-4) at (25dB) for K = 10, when MRC diversity combining technique is used on the case study of K =2 curve the system was able to achieve average BER of (10-7) for less than (15dB) at diversity order of (6), compared to (10-2) at (15dB) for a single channel receiver with the same value of K.

For the Hoyt channel GMSK was unable to pass the (10-3) bit error rate barrier as a single channel receiver but the system achieved (10-7) at average signal to noise ratio of (15dB) for an MRC receiver with diversity order of (6).

For Nakagami when the parameter ) m) is increased the system performance gets better as a single channel receiver, the worst case scenario was for m = 0.5 as the system was unable to pass an average BER of (10-1) at (30dB) but when using M^C the system was able to achieve average BER of (10-7) at (22dB) for diversity order of (6).

Main Subjects

Telecommunications Engineering

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-417352