Pre-Reply Probe and Route Request Tail: Approaches for Calculation of Intra-Flow Contention in Multihop Wireless Networks

Several applications have been envisioned for multihop wireless networks that require different qualities of service from the network. In order to support such applications, the network must control the admission of flows. To make an admission decision for a new flow, the expected bandwidth consumption of the flow must be correctly determined. Due to the shared nature of the wireless medium, nodes along a multihop path contend among themselves for access to the medium. This leads to intra-flow contention; contention between packets of the same flow forwarded by different hops along a multihop path, resulting in an increase in the actual bandwidth consumption of the flow to a multiple of its single hop bandwidth requirement. Determining the amount of intra-flow contention is non-trivial since interfering nodes may not be able to communicate directly if they are outside each other's transmission range. In this paper we examine methods to determine the extent of intra-flow contention along multihop paths in both reactive and proactive routing environments. The highlight of the solutions is that carrier-sensing data is used to deduce information about carrier-sensing neighbors, and no high power transmissions are necessary. Analytical and simulation results show that our methods estimate intra-flow contention with low error, while significantly reducing overhead, energy consumption and latency as compared to previous approaches. Kimaya Sanzgiri is a PhD candidate in the Department of Computer Science at the University of California, Santa Barbara. She is working with Prof. Elizabeth Belding-Royer in the Mobility Management and Networking (MOMENT) Laboratory. Kimaya received her B.E. (Hons.) in Computer Science from the Birla Institute of Technology and Science (BITS), Pilani, India in 1999. Her research interests are in the area of wireless networking, specifically mobility, quality of service support and security. See for more details. Ian D. Chakeres is an Ph.D. student in the Department of Electrical and Computer Engineering at the University of California, Santa Barbara. He is working with Prof. Elizabeth M. Belding-Royer in the Mobile Management and Networking (MOMENT) Laboratory. He completed his B.S. and M.S. in Electrical and Computer Engineering at Ohio State University in 1998 and 1999. He is also a co-chair of the IETF MANET working group. Ian's research interests include wireless communication and mobile networking, specifically routing protocols, MAC protocols, cross-layer coordination and quality of services in mobile wireless networks. See for further details. Elizabeth M. Belding-Royer is an Assistant Professor in the Department of Computer Science at the University of California, Santa Barbara. She completed her Ph.D. in Electrical and Computer Engineering at UC Santa Barbara in 2000. Elizabeth's research focuses on mobile networking, specifically routing protocols, multimedia, monitoring, and advanced service support. Elizabeth is the author of numerous papers related to ad hoc networking and has served on many program committees for networking conferences. Elizabeth is the TPC Co-Chair of ACM MobiCom 2005 and IEEE SECON 2005, and is currently on the editorial board for the Elsevier Science Ad hoc Networks Journal. Elizabeth is the recipient of an NSF CAREER award, and a 2002 Technology Review 100 award, awarded to the world's top young investigators. She is a member of the IEEE, IEEE Communications Society, ACM, and ACM SIGMOBILE. See for further details.