NetSwap - Seamless Roaming Between Wireless Networks

This project is concerned with the research and development of a solution which would help mobile nodes to roam between different types of wireless network seamlessly.

The two wireless network protocols that are of interest in this project are 802.11b (WiFi), a wireless local area network which is increasingly being used in homes and offices, and GPRS, a wireless wide area network which works as a data extension to the GSM mobile phone network.

The project commences by researching current wireless network technologies and solutions. Subsequently the problem is discussed in further detail and a new software based solution, which would decrease network swapping errors, is proposed and documented.

The new solution, NetSwap, is implemented in network simulation software and tested against results from previous tests with encouraging results.

Dissertation:

"Seamless Roaming Between Wireless Networks", J. Saunders, Final Year Dissertation undertaken in fulfilment of the requirements for the BSc (Honours) Degree in Computer Science for the University of Portsmouth UK. May 2004
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Papers:

"Seamless Roaming between GPRS and WiFi Networks" M. Adda and J. Saunders. for presentation at the 1st Thailand Computer Science conference, Thailand, 16-17 December 2004
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"A simple implementation to roaming between GPRS and WiFi Networks" M. Adda, J. Saunders, A. Peart. PP 81-87, ISBN 84-933971-1-3, IADAT International Conference on Telecommunications and Computer Networks, Spain , December 1-3, 2004
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Contents

Acknowledgements
1. Introduction
1.1 Background
1.2 The Problem
2. Network Technology Research
2.1 Ethernet
2.1.1 Ethernet Background
2.1.2 Ethernet Frames
2.1.3 Ethernet Speeds
2.2 WiFi 802.11a/b
2.2.1 WiFi Background
2.2.2 WiFi Technology/Infrastructure
2.2.3 WiFi Frames
2.2.4 WiFi Speeds
2.3 GPRS (General Packet Radio Service)
2.3.1 GPRS Background
2.3.2 GPRS Technology/Infrastructure
2.3.3 GPRS Frames
2.3.4 GPRS Speeds
3. Current Solutions
3.1 Mobile IP
3.1.1 Mobile IP Detail
3.1.2 Problems with Mobile IP
3.2 Occasionally Connected Computing (OCC)
3.2.1 Problems with OOC
3.3 DSP Silicon Methods
3.3.1 System on Chip (SoC)
3.3.2 Software Defined Radio (SDR)
3.3.3 Problems with DSP Silicon Methods
4. Analysis and Design
4.1 Brief
4.1.1 The NetSwap Driver
4.1.2 The NetSwap Gateway
4.2 Class Diagrams
4.3 Sequence Diagrams
4.3.1 Simple Scenario
4.3.2 If things go wrong
4.4 Pseudo Code
5. Implementation
5.1 Physical Hardware Simulation
5.2 Physical Hardware Implementation
5.2.1 Software Used
5.2.2 Equipment Setup - Architecture
5.2.3 Simulating the effect of ?Roaming?
5.2.4 Application Configuration
5.2.5 Recording Findings
5.3 Software Simulation of the NetSwap Idea
5.3.1 OPNET
5.3.2 QualNet
5.3.3 OMNeT++
5.3.4 NS-2
5.4 NS-2 Implementation
5.4.1 Getting to know NS-2
5.4.2 Configuration
5.4.3 First NS-2 Tcl Script
5.4.4 Recreating problem in NS-2
5.4.5 Creating the NetSwap Agents
5.5 Problems and Restrictions of NS-2
5.5.1 Timer
5.5.2 Addressing Scheme
5.5.3 GPRS Patch
6. Testing and Evaluation
6.1 Physical Testing
6.1.1 Task Manager Network Monitor
6.1.2 CuteFTP
6.1.3 Streaming Audio using Microsoft Media Player
6.1.4 Ping
6.2 NS-2 Testing
6.2.1 FTP, before NetSwap implementation
6.2.2 FTP, after NetSwap implementation
6.3 Comparison of NS-2 & Physical Results
6.3.1 FTP Comparisons
6.3.2 Media Player Comparisons
6.3.3 Ping Comparisons
7. Conclusion and Future Work
7.1 Future Work
7.1.1 Real Hardware Implementation of NetSwap
7.1.2 Error Detection
7.1.3 Old IP address fallback
7.1.4 Changing of the return IP address
7.1.5 Multiple Users
8. Evaluation against the requirements
Bibliography
Glossary of Terms
Glossary of Symbols
Appendix A - Packet Headers
IP Header
TCP Header
ICMP Header
Ethernet Header & Trailer
802.11 Wireless Header & Trailer
RLC Downlink Header
Appendix B - OSI Layers
Appendix C ? NetSwap Classes
Appendix D ? Results
Appendix E ? Main NS-2 NetSwap Code
Appendix F ? NS-2 NetSwap Tcl Script