Communication protocols for wireless ad-hoc and sensor networks

by Ding, Jin.

by Jin Ding, Ph.D. Washington State University May 2006 Chair: Sirisha Medidi Demand for decentralized wireless ad-hoc systems, where hosts are free to leave or join, to replace wired communication systems has seen a phenomenal growth. The protocols developed for wired systems cannot handle the new problems that come with wireless networks. This inability lays our entire communications capability open to disruption, and requires entirely new protocols. Traditional TCP (Transport Control Protocol), designed for wired networking, degrades significantly over wireless links and provides abysmal throughput. This performance degradation occurs because the TCP protocol is carefully tuned for wired networks, where most packet losses are primarily due to congestion loss. However, in wireless ad-hoc networks, packet loss could be because of several reasons such as link loss, node mobility and network misbehavior to name a few. Current techniques for improving TCP do not consider the malicious packet drop attack. Energy-efficient information dissemination is a critical operation in wireless sensor networks. Conventional protocols like flooding or gossiping have problems such as data implosion, overlap, and resource blindness. SPIN (Sensor Protocols for Information via Negotiation), proposed to handle these issues uses negotiation with meta-data descriptors and resource-adaptation. However energy-efficiency was not considered in this design. This dissertation addresses these challenges by providing two communication protocols, one that improves TCP performance over lossy links and another that provides energy-efficient data distribution. First, TCP-Manet, a reliable transport protocol over wireless ad-hoc networks is introduced. TCP-Manet determines the characteristics of the packet loss based on current connection status and reacts effectively to the packet loss. Theoretical and simulation results show that TCP-Manet provides better iv throughput performance than TCP-Reno. Next, SPIN-G, an energy-efficient data dissemination protocol is developed. SPIN-G adapts to the remaining battery power at any sensor node there by extending network lifetime. This protocol also uses the negotiation, meta-data description, and resource adaptation features of SPIN and improves on the negotiation by explicitly accounting for the battery capacity. Simulation experiments confirm that SPIN-G dissipates less energy compared to SPIN and converges (all nodes in the network get all the data) slightly slower than SPIN. v