Interactions between TCP and Channel Type Switching in WCDMA

Internet and mobile communications dominate the development of the telecommunications industry today. The main application of 3G systems will be packet transfer to the Internet access and therefore TCP is likely going to be the most dominant communication protocol. The technology challenge is to optimise TCP/IP protocols that were originally designed for reliable wired networks, over wireless environments that are characterised by high error rates and long delays. Since very little is known about the impact of radio resource management procedures on the TCP protocol this thesis is focused on TCP and its interactions with the resource allocation. In particular, the goal is to create an understanding on how the performance of TCP is influenced by the interaction of WCDMA channel type switching procedures, errors over the radio link and bearer capacity. The results show that frequent channel switches during a connection degrades the performance of TCP over WCDMA links, the connection recovers badly from continuous variations in the radio link round trip time and the number of spurious timeouts increases. Moreover, the influence of channel switching delays is particularly harmful for very low error probability radio links combined with TCP over wireless split approaches. It is also found, that the impact of frequent channel switches during a file transfer is negligible provided that an appropriate error rate target is selected. 2 (78) Prepared (also subject responsible if other) No. KI/ERA/T/BU Patricia Muñoz Garrosa T/B-01:241 Approved Checked Date Rev Reference T/BUC Göran Malmgren KES 2002-01-29 A CAR-RP 3 (78) Prepared (also subject responsible if other) No. KI/ERA/T/BU Patricia Muñoz Garrosa T/B-01:241 Approved Checked Date Rev Reference T/BUC Göran Malmgren KES 2002-01-29 A CAR-RP PREFACE This master science thesis was performed by Patricia Muñoz Garrosa, graduate student at the Polytechnical University of Madrid (Spain), and Master student at the Chalmers University of Technology in Gothenburg (Sweden). The thesis work was performed at Ericsson Radio System, Ericsson Research, in Kista (Sweden.) 4 (78) Prepared (also subject responsible if other) No. KI/ERA/T/BU Patricia Muñoz Garrosa T/B-01:241 Approved Checked Date Rev Reference T/BUC Göran Malmgren KES 2002-01-29 A CAR-RP 5 (78) Prepared (also subject responsible if other) No. KI/ERA/T/BU Patricia Muñoz Garrosa T/B-01:241 Approved Checked Date Rev Reference T/BUC Göran Malmgren KES 2002-01-29 A CAR-RP ACKNOWLEDGEMENTS First and foremost, I would like to thank my supervisor Kai-Erik Sunell for his help and encouragement throughout my work, for reading and correcting my report, and for answering all my questions. He has been an excellent guide in the art of writing a thesis. I would also like to thank all the members of Access Networks, Ericsson Research Corporate Unit for their help and support in various ways during my stay in Ericsson Radio Systems in Kista. Special thanks to Professor Arne Svensson and Johan Lassing from Chalmers University of Technology in Gothenburg (Sweden), for spending their valuable time reading and correcting the thesis. Thanks also to my Erasmus coordinator in Sweden, Leif Lundkvist, to the Chalmers International Office and to the Erasmus bureau at the Polytechnical University of Madrid, for helping me with the administrative and everyday problems during my stay in Sweden. Thanks to my friends at the Polytechnical University of Madrid, Chalmers University of Technology and the Royal Institute of Technology, for many fruitful technical discussions and all the great moments we have spent together. Most of all I would like to express my gratitude to my beloved family for being always there. And last, but not least, I would also extend my heartfelt and sincere thanks to all you who helped and supported me in various ways during these last years. 6 (78) Prepared (also subject responsible if other) No. KI/ERA/T/BU Patricia Muñoz Garrosa T/B-01:241 Approved Checked Date Rev Reference T/BUC Göran Malmgren KES 2002-01-29 A CAR-RP 7 (78) Prepared (also subject responsible if other) No. KI/ERA/T/BU Patricia Muñoz Garrosa T/B-01:241 Approved Checked Date Rev Reference T/BUC Göran Malmgren KES 2002-01-29 A CAR-RP