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
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
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
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
4. The Simulation and Result for the TBVH
4.1 Why Matlab program
4.2 Modulation
4.3 Decision algorithm
5. Conclusion and Future work
Objectives and Research Themes
The primary objective of this dissertation is to investigate and resolve the challenges associated with signal interference and connection stability during handovers in GSM systems. The study focuses on calculating the optimal timing and distance for vertical handover (VHO) between different access networks to ensure a seamless and secure connection for mobile users.
- Analysis of various GSM handover mechanisms and their associated failure points.
- Distinction and comparison between horizontal and vertical handover strategies.
- Mathematical modeling of "Time Before Vertical Handover" (TBVH) for both indoor and outdoor environments.
- Implementation of a Matlab-based simulation to validate the proposed mathematical calculations.
- Development of a decision algorithm to predict the next position of a mobile node for handover execution.
Excerpt from the Book
3.1.1 Time Before Vertical Handover (for outdoor environments)
This scenario is concerned with the mobile node in an outdoor setting but under the WLAN coverage, moving in the direction of the BS boundary with a velocity v as the following figure shows: The considered networks are UMTS (or GSM) and WLAN where any other networks can be used. Here, a circular coverage cell has been suggested with a radius R instead of the hexogen cell. The above figure shows the inner dotted circle with a radius r; both represent the handover threshold when the mobile node is expected to have a vertical handover. Moreover, x is the angle made by the MN when moving towards the BBS. D is the distance between the MN and the BBS. Z is the point on the threshold circle when the MN expects to have a vertical handover. Applying Pythagoras theorem, the following equation will be used to calculate z.
Summary of Chapters
1. Introduction: Provides a foundational overview of GSM technology, the necessity of handover for maintaining mobile connectivity, and an introduction to connection establishment concepts in WLANs.
2. Literature review: Examines existing research regarding handover definitions, techniques (hard, soft, softer), reasons for failure, and provides a comparative analysis of horizontal and vertical handovers.
3. The focus- calculate the optimal timing and distance for GSM vertical handover: Focuses on the mathematical derivation of optimal timing and distance for vertical handovers, specifically modeling indoor and outdoor movement scenarios.
4. The Simulation and Result for the TBVH: Details the Matlab-based implementation of the proposed TBVH model, providing simulation results, flow charts, and a decision algorithm for vertical handover.
5. Conclusion and Future work: Summarizes the study’s findings regarding handover optimization and suggests future research directions, including the use of C++ and MySQL for enhanced security and complexity.
Keywords
GSM, Handover, Handoff, Vertical Handover, VHO, Wireless Networks, Signal Interference, Matlab, TBVH, Time Before Vertical Handover, Connection Establishment, WLAN, QoS, Mobile Node, Simulation
Frequently Asked Questions
What is the core focus of this research?
The research primarily investigates the signal interference problems in GSM systems during handovers and proposes a mathematical model to calculate the optimal time and distance for vertical handovers (VHO).
What are the main research themes?
Key themes include the comparative analysis of handover types (horizontal vs. vertical), the mathematical modeling of "Time Before Vertical Handover" (TBVH), and the implementation of simulation software to validate handover decision algorithms.
What is the main goal of this work?
The goal is to provide GSM users with a more reliable and secure signal connection by minimizing handover failures through precise timing and distance calculations.
What methodology is applied?
The researcher uses mathematical modeling based on Pythagoras' theorem to derive TBVH equations and validates these findings through numerical simulations in the Matlab environment.
What is covered in the main body of the dissertation?
The main body covers the literature review of handover techniques, the detailed mathematical derivation for outdoor and indoor scenarios, and the creation of Matlab pseudo-code for predictive handover algorithms.
What are the characterizing keywords?
Significant keywords include GSM, Handover, Vertical Handover (VHO), Matlab, Signal Interference, and TBVH.
How does the model handle indoor versus outdoor environments?
The dissertation derives distinct equations for both environments, accounting for factors like topological constraints in indoor settings and circular coverage thresholds in outdoor settings.
What role does Matlab play in this study?
Matlab is used to perform high-speed numerical calculations, visualize the relationship between distance and handover timing, and test the proposed decision algorithms.
What is the "Ping pong effect" mentioned in the study?
It describes an undesirable scenario where a mobile node performs multiple unnecessary handovers between base stations due to signal fluctuations, which the study seeks to mitigate.
- Quote paper
- Rand Raheem (Author), 2011, Handover Strategies in GSM System, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/200825
