First of all I want to thank my advisors for introducing me to the topic and leading me through the thesis with lots of discussions that were helpful to refine and improve my ideas. Especially I would like to thank the advisors for helping me to get the two invention disclosures done, so the ideas could be patented fast enough so I can disclose my work.

I want to thank the Siemens CT IC 2 department for offering me the topic and sup-porting me so well and also for taking me as a colleague. Thanks to my colleague Khan Muddassir for the excellent teamwork, which was a great profit for both of us.

Also thanks to the OpenWRT developer Imre Kaloz for his nightlong explanations on how to flash a bootloader on the NP18A device.

Also thanks to Sudiadi from the Compex support desk for the modification files to the buildroot, so I could create own OpenWRT images for the Compex WP18. I also want to thank Eva Hund for the correction work on my master thesis. Last but not least I want to thank my parents for countless helping hands during the time of the master thesis and my brother for the donation of his notebook. Thanks also to all the unnamed helpers who made this master thesis possible.

- 3 -

Table of Contents

Table of  Contents  

1.  Introduction  7

1.1.  Network Coding.  7

1.1.1.  Principle.  7

1.1.2.  Linear Coding.  11

1.1.3.  Deterministic Coding.  12

1.1.4.  Decentralized network coding.  12

1.1.5.  Random Coding.  13

1.2.  Peer-to-Peer Swarming.  13

1.2.1.  Microsoft Avalanche.  13

1.2.2.  Codetorrent.  14

1.3.  Haggle.  14

1.4.  COPE.  18

1.4.1.  Opportunistic Listening.  19

1.4.2.  Opportunistic Coding.  20

1.4.3.  Opportunistic Routing.  22

1.4.4.  Pseudo Broadcast.  23

1.4.5.  Realization of the Cope principle.  23

1.4.6.  Performance Bottlenecks for TCP.  25

2.  Implementations  27

2.1.  MIT Reference Implementation.  27

2.1.1.  CLICK.  27

2.1.2.  Roofnet.  30

2.1.3.  Madwifi-stripped.  32

2.1.4.  COPE elements.  32

2.2.  OpenWRT.  33

2.2.1.  Stable Branch / White Russian.  33

2.2.2.  “Bleeding Edge / Kamikaze.  33

2.2.3.  Buildroot Environment.  33

2.2.4.  Packages.  34

2.2.5.  Image Deploying / Flashing.  36

- 4 -

Table of Contents

3.  Measurements  38

3.1.  Layout of the experiments.  38

3.1.1.  Retransmissions.  39

3.1.2.  Bandwidth.  39

3.1.3.  Memory leak.  39

3.2.  Measurement results.  39

3.2.1.  Throughput without coding.  40

3.2.2.  Throughput with coding.  40

3.2.3.  Analysis.  41

3.3.  Conclusion of the experiments.  41

4.  Resilience through redundancy  43

4.1.  Zaib Quality of Service.  43

4.1.1.  Problems Addressed.  43

4.1.2.  Improvements.  44

4.1.3.  Complete solution.  44

4.1.4.  Example.  48

4.1.5.  Simulation / Analysis.  49

4.2.  Adaptive Preventive Redundancy.  49

4.2.1.  Problems addressed.  49

4.2.2.  Improvements.  50

4.2.3.  Complete solution.  51

4.2.4.  Example.  52

4.2.5.  Advantages against Reed-Solomon Coding.  53

4.3.  Outlook.  53

Appendix A  Current QoS implementation  54

Appendix B  Porting Cope  56

B.1  Native Implementation.  56

B.2  Roofnet/Click on OpenWRT.  56

B.2.1  Berlinroofnet.  57

B.2.2  MIT Roofnet Package.  58

- 5 -

Table of Contents

B.2.3  Patching COPE Reference Implementation.  58

B.2.4  Modifications on Cope.  58

B.2.5  OpenWRT development.  59

B.3  Modifications on Cope to run on broadcom.  62

Appendix C  Cope packet handling  63

C.1  Alice sending.  63

C.2  Router.  65

C.3  Alice receiving.  69

C.4  Bob.  70

Appendix D  Click configuration File  72

Appendix E  Measurement results  81

Index  of Figures  87

Index  of Tables  88

Bibliography   89

Affidavit   92

- 6 -