Handover Strategies in GSM System

Master's Thesis , 2011 , 49 Pages , Grade: Merit

Computer Science - Internet, New Technologies

GSM is one of the greatest wireless technologies in the world because of the benefits it provides to its users in saving time and its ability in speeding signals. Unfortunately, under the GSM system, the signal interference which users might experience when moving from one coverage area to another presents a real problem. The main objective of this project was to investigate and simultaneously resolve the problem of the GSM handover system. This project is explaining the mechanism of the signal transmits and handover from one antenna to another taken into consideration that transmission may vary according to the type of the handover.

The project attempted then to introduce and compare between all these different types of handover, and decide the ideal type for reserving the signal from any cut or interference. The location of the MS is really the core in tackling the signal interference problem under the system. Therefore, the optimal timing and distance between handover facilities was calculated to solve the problem. The focus of this project is on vertical handover and specially the time before vertical handover. Later on, the project also showed the calculations concerning timing and distance between antennas (or coverage areas) by taking into account the velocity of the mobile node movement. In short, the focus of this project is to investigate the GSM signal interference problem, find the solutions to these problems through the calculation of the ideal timing and distance between antennas and then apply these calculated results in constructing GSM handover facilities.

This project is attempting to provide GSM users with the smoothest and the most secure signal connection when travelling between coverage areas. Matlab program will be used in order to calculate both time and distance of vertical handover. All the results were listed to prove the manual calculations. A conclusion ended the project summing up the main findings of the study and some suggestions for further studies were offered.

It is to be mentioned here that the previous works specifically the one that is concerning about calculating the time and distance of TBVH were the foundation of this project. Unlike other researches who used the OPEN modeller, this project is using Matlab software to calculate the time and distance of TBVH. As a matter of fact, the present study gave a pseudo code in Matlab for predicting the position of vertical handover.

Table of Contents

Abstract

List of Figures

List of Tables

Abbreviations

Acknowledgment

Chapter 1
1. Introduction
1.1 History of GSM
1.2 Overview of GSM handover
1.2.1 Between calls
1.2.2 During a call
1.3 The connection establishment in WLAN and the scanning concept
1.3.1 Discovery
1.3.2 Authentication
1.3.3 Association, Disassociation and Re-association
1.3.4 Confidentiality
1.3.5 The AP discovery and association
1.3.5.1 Passive scanning
1.3.5.2 Active scanning

Chapter 2
2. Literature review
2.1 Definition of the handover process
2.2 Types of handover technique
2.3 Reasons of handover failure
2.4 The differences between hard, soft and softer handoffs
2.5 SYNC handovers and asynchronous handover
2.6 Emergency handovers
2.7 Vertical and horizontal handover
2.8 “Multilayer Handover” Strategy, “Ping pong effect” and “take-back”
2.9 Handover decisions in GSM
2.10 GSM handover solutions
2.11 Mathematical calculations and modulations

Chapter 3
3. The focus- calculate the optimal timing and distance for GSM vertical handover
3.1 Time Before Vertical Handover (TBVH)
3.1.1 Time Before Vertical Handover (for outdoor environments)
3.1.2 Time Before Vertical Handover (for indoor environments) - Mobile node movement from a normal BS to BBS

Chapter 4
4. The Simulation and Result for the TBVH
4.1 Why Matlab program
4.2 Modulation
4.3 Decision algorithm

Chapter 5
5. Conclusion and Future work

References

• College: ( Middlesex University in London )
• Course: MSc in Telecommunication Engineering
• Grade: Merit
• Author: Rand Raheem (Author)
• Publication Year: 2011
• Pages: 49
• Catalog Number: V200825
• ISBN (eBook): 9783656270188
• ISBN (Book): 9783656270812
• Language: English
• Tags: handover, strategies, system