Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 450 Challenged Networking An Experimental Study of new Protocols and Architectures ERIK NORDSTRÖM ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 UPPSALA ISBN 978-91-554-7239-9 2008 urn:nbn:se:uu:diva-9002 !"#$" % & '$ (() '$*'# + + + , - . , / 0 , ((), 1 /. , + . , , 2#(, 33 , , 45/ 6")!6'!##2!"$6!6, 7 . + 4 . , - 4 . . + . . , 4 . . . . , 8 , 7 . + + , 7 + . , 5 . + . . + . . , 8 + 9 : , 4 + . . , - + . . , . !! + + 4 -% ;/ - , . + + '( . 9 !:, 7 + < ,, . + , 7 , 8 . = , 4 , ; . . , 7 , 7 . . ., 1 . /. 7 /. - /. 8 /. - , ! " # " $ % &&'" " (')*+) " > / 0 (() 4/ '3#'!3'2 45/ 6")!6'!##2!"$6!6 * *** !6(( 9 *?? ,,? @ A * *** !6((: If I have seen further it is by standing on the shoulders of giants. Sir Isaac Newton Preface Five years make a long time. It is certainly ample time to ponder on the reasons for pursuing a Ph.D., and for engaging in research. Many such reasons that are now obvious to me were not clear at the beginning of my journey – they have emerged gradually during the course of it. One of the reasons for engaging in research, which I believe in, is to con- tribute to a common pool of knowledge. There is a famous saying that we are standing on the shoulders of giants1. Furthering our knowledge is a collabora- tive process that consists of incremental steps. This process is how we in the long run affect the evolution of our society and, by extension, our world. Some thinkers of course produce more disruptive research than others. However, whether research is disruptive or not, often only time can tell. In either case, if research is not accessible, interesting, understandable, and educational for people, it might as well never have existed to begin with. Informing others of your research, especially those that are not professionals, I have learnt can be highly motivational and constructive for your work – but it is also a major challenge. Fortunately, this thesis is all about challenges. Thus, a goal has been to make this thesis accessible (at least in parts) also to people not necessarily familiar with computer networking. Whether I have succeeded or not is up to the reader to decide. This goal, however, does not imply that this thesis is free from technical jargon and intricate details. So beware! Often friends and family have asked me about my research. Equally often I have tried to avoid giving an answer. One reason for this unwillingness to explain is simply that I prefer not to talk about work when I am not working. Another reason is that I quickly learned that it was hard to explain in limited time (e.g., imagine doing it at a party before a person looses interest), or that it was obvious that the person was just being polite by asking – and in fact could not care less. The people that actually do want to know: here is your chance! Keep on reading. During five years many things can change – not only in terms of research, but also in life in general. This life I quickly learnt can suffer if you are sucked too deeply into what you are doing. I therefore decided early on that I would honor the life outside of work, and at the same time to embrace some of the perks of being a doctoral candidate in my area. These perks include free plan- 1This metaphor is attributed Bernard of Chartres, but was made famous by Sir Isaac Newton. v ning of time (which can both be a blessing and a curse), working in an environ- ment where you meet and interact with people of many different backgrounds, and last but not least the opportunity to travel to many interesting countries and places. These perks have not only been good for me as a researcher; they have also made me a better and more enlightened person. To have had the fortune to do all these things, such as enjoying perks and engaging in interesting research, has been a privilege. This privilege would not have been possible without the support of many people. My gratitude goes to all of these people, which I will here try to list without forgetting someone. My gratitude first and foremost goes to my closest family: my parents Jan- Eric and Eva, and my sister Jenny. They have not always understood what I have been doing in my research, but have always supported me in my decision to pursue it. When life has been difficult, in work or otherwise, they have always been there to pick me up. My closest family, and my other relatives, have my everlasting love and gratitude. My friends outside of work have been my retreat and safe haven from ev- erything work related. They are too numerous to list here, and if I tried I would be afraid to forget somebody. You know who you are! I am grateful for having such diverse friends that do everything but researching challenged network- ing. They have given me broader perspectives, which undoubtedly have made me better in many ways, including in my research. My colleagues in the Communications Research (CoRe) group have been instrumental to my success as a Ph.D. candidate. These are: Richard Gold, my partner-in-crime and friend. Endless have our discussions been – sometimes heated, often challenging, always insightful. I am grateful for these insights, for the patience shown when listening to my complaints at times of low moti- vation, and for reminding me not to take work too seriously when I shouldn’t. Olof Rensfelt, whose research seems to be only one hobby of many that he excels in. Apart from his research, I especially appreciate his beer making skills and excellent cooking, which can always be enjoyed through a level of hospitality challenged only by his wife Agnes. Henrik Lundgren, who during my first year was my close collaborator and co-author on many of my papers. He is a friend that was a familiar face in Paris during my visit there. Chris- tian Rohner who has been a loyal work companion, and has always been able to put up with my sometimes strong opinions on how to do things. Christian Tschudin, who after he left the group has acted as my external supervisor. His refreshing ideas and unchallenged technical skills have been an inspiration. David Lundberg and Mattis Fjällström, who I have had the privilege working with early on in my studies. The rest of the colleagues in the CoRe group have always inspired and supported; Lars-Åke Larzon, Arnold Pears, Oskar Wibling, Ioana Rodhe, Fredrik Bjurefors, Thabotharan Kathiravelu, and Laura Feeney. Numerous are also the students, research assistants, alumni people, and visitors that I have been fortunate enough to have met and interacted with. All of these people have my gratitude. vi I am also thankful to my colleagues at the Thomson research lab in Paris, where I did an internship (2006-2007). Christophe Diot, who was kind enough to host me, and whose open mind (often spoken in a refreshingly direct man- ner) gave me fresh inspiration during the final years of my Ph.D. studies. My gratitude also goes to all of the others in the lab that made my stay in Paris a rememberable one: Amogh, Vivek, Andy, Augustin x 2, Laurent, Vincent, Letizia, Haakon, Ming, Abderrahmen, Theodoros, Anna-Kaisa, Fer- nando, Marianna, and others. Last, but not least, my supervisor and mentor Per Gunningberg. He has always believed in me, supported me, and given me the freedom that every researcher wants – but perhaps not always takes advantage of to the fullest. I owe him much, and for this he has my deepest gratitude and greatest respect. vii List of Included Papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. I Henrik Lundgren, David Lundberg, Johan Nielsen, Erik Nord- ström and Christian Tschudin, “A Large-scale Testbed for Re- producible Ad hoc Protocol Evaluations”. In Proceedings of The Third Annual IEEE Wireless Commmunications & Networking Conference (WCNC), March 2002. II Henrik Lundgren, Erik Nordström and Christian Tschudin, “Coping with Communication Gray Zones in IEEE 802.11b based Ad hoc Networks”. In Proceedings of The Fifth ACM International Workshop on Wireless Mobile Multimedia (WoWMoM), September 2002. III Erik Nordström, Per Gunningberg and Christian Tschudin, “Ro- bust and Flexible Internet Connectivity for Mobile Ad hoc Net- works”. An extended version of the paper: “Comparison of For- warding Strategies in Internet Connected MANETs”, published in ACM SIGMOBILE Mobile Computing and Communications Review (MC2R), Volume 8, Issue 4, Pages 72-76, October 2004. IV Christian Tschudin, Per Gunningberg, Henrik Lundgren and Erik Nordström, “Lessons from Experimental MANET Research”.In Elsevier Journal on Ad hoc Networks, Volume 3, Issue 2, Pages 221-233, March 2005. V Erik Nordström, Per Gunnningberg and Henrik Lundgren, “A Testbed and Methodology for Experimental Evaluation of Mobile Ad hoc Networks”. In Proceedings of The First International Con- ference on Testbeds and Research Infrastructures for the Devel- opment of Networks and Communities (TRIDENTCOM), Febru- ary 2005. VI Erik Nordström, Per Gunningberg, Christian Rohner and