IEEE 802.11b Ad Hoc Networks: Performance Measurements

In this paper we investigate the performance of IEEE 802.11b ad hoc networks by means of an experimental study. An extensive literature, based on simulation studies, there exists on the performance of IEEE 802.11 ad hoc networks. Our analysis reveals several aspects that are usually neglected in previous simulation studies. Firstly, since different transmission rates are used for control and data frames, different transmission ranges and carrier-sensing ranges may exist at the same time in the network. In addition, the transmission ranges are in practice much shorter than usually assumed in simulation analysis, not constant but highly variable (even in the same session) and depends on several factors. Finally, the results presented in this paper indicate that for correctly understanding the behavior of an 802.11b network operating in ad hoc mode, several different ranges must be considered. In addition to the transmission range, the physical carrier sensing range is very important. The transmission range is highly dependent on the data rate and is up to 100 m, while the physical carrier sensing range is almost independent from the data rate and is approximately 200 m. Furthermore, even though stations are outside from their respective physical carrier sensing range, they may still interfere if their distance is lower than 350 m.Giuseppe Anastasi received the Laurea degree in Electronics Engineering and the Ph.D. degree in Computer Engineering both from the University of Pisa, Italy, in 1990 and 1995, respectively. He is currently an associate professor of Computer Engineering at the Department of Information Engineering of the University of Pisa. His research interests include architectures and protocols for mobile computing, energy management, QoS in mobile networks, and ad hoc networks. He was a co-editor of the book Advanced Lectures in Networking (LNCS 2497, Springer, 2002), and published more than 50 papers, both in international journals and conference proceedings, in the area of computer networking. He served in the TPC of several international conferences including IFIP Networking 2002 and IEEE PerCom 2003. He is a member of the IEEE Computer Society.Eleonora Borgia received the Laurea degree in Computer Engineering from the University of Pisa, Italy, in 2002. She is currently working toward her Ph.D. degree at the IIT Institute of the Italian National Research Council (CNR). Her research interests are in the area of the wireless and mobile networks with particular attention to MAC protocols and routing algorithms for ad hoc networks.Marco Conti received the Laurea degree in Computer Science from the University of Pisa, Italy, in 1987. In 1987 he joined the Italian National Research Council (CNR). He is currently a senior researcher at CNR-IIT. His research interests include Internet architecture and protocols, wireless networks and ad hoc networking, mobile computing, and QoS in packet switching networks. He co-authored the book Metropolitan Area Networks (Springer, London, 1997), and published in journal and conference proceedings more than 100 research papers related to design, modeling, and performance evaluation of computer-network architectures and protocols. He served as the technical program committee chair of the IFIP-TC6 conferences Networking 2002 and PWC 2003, and technical program committee co-chair of ACM WoWMoM 2002. He is serving as technical program committee co-chair of the IEEE Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM 2005). He served as guest editor for the Cluster Computing Journal (special issue on Mobile Ad Hoc Networking), IEEE Transactions on Computers (special issue on Quality of Service issues in Internet Web Services), and ACM/Kluwer Mobile Networks & Applications Journal (special issue on Mobile Ad hoc Networks). He is member of IFIP WGs 6.2, 6.3 and 6.8.Enrico Gregori received the Laurea in electronic engineering from the University of Pisa in 1980. He joined CNUCE, an institute of the Italian National Research Council (CNR) in 1981. He is currently a CNR research director. In 1986 he held a visiting position in the IBM research center in Zurich working on network software engineering and on heterogeneous networking. He has contributed to several national and international projects on computer networking. He has authored more than 100 papers in the area of computer networks and has published in international journals and conference proceedings and is co-author of the book Metropolitan Area Networks (Springer, London, 1997). He was the General Chair of the IFIP TC6 conferences: Networking2002 and PWC2003 (Personal Wireless Communications). He served as guest editor for the Networking2002 journal special issues on: Performance Evaluation, Cluster Computing and ACM/Kluwer Wireless Networks Journals. He is a member of the board of directors of the Create-Net association, an association with several Universities and research centres that is fostering research on networking at European level. He is on the editorial board of the Cluster Computing, of the Computer Networks and of the Wireless Networks Journals. His current research interests include: Wireless access to Internet, Wireless LANs, Quality of service in packet-switching networks, Energy saving protocols, Evolution of TCP/IP protocols.