Handover Strategies in GSM System

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

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.