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Unformatted text preview: IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 54, NO. 1, JANUARY 2005 307 Contact-Extended Zone-Based Transactions Routing for Energy-Constrained Wireless Ad Hoc Networks Ahmed Helmy , Member, IEEE Abstract In future wireless ad hoc networks, transactions are expected to become one of the primary types of flows. Transac- tions require only a small number of packets to complete. Hence, providing optimal (shortest path) routes to such transactions consumes more energy than the actual data transfer. Conventional shortest path routing protocols are, thus, unsuitable for routing transactions. In this paper, we present a novel architecture, called TRANSFER, for transactions routing in large-scale wireless ad hoc networks. In our approach, we aim to reduce the total energy consumption by transactions as opposed to finding shortest path routes. Our architecture uses a hybrid approach, in which each mobile node obtains information about nodes in its proximity (zone), up to hops away, using a proactive link-state protocol. Beyond the proximity, we introduce the novel notion of contacts that act as shortcuts to reduce the degrees of separation between the source of the transaction and the destination. We propose an efficient on-demand protocol for contact selection that does not assume knowledge of location information. Contacts are used during transactions and queries to discover valid routes in an en- ergy-efficient manner. Extensive simulations are used to evaluate the performance of our protocol in terms of energy consumption and success rate. We compare our architecture to flooding, dy- namic source routing (DSR), zone-routing protocol (ZRP), and two power-aware schemes. Our results show substantial power savings for our contact-based protocol, especially for large ad hoc networks. Index Terms networks, contact-based architecture, energy efficiency, network simulation, routing protocol. I. INTRODUCTION A D HOC wireless networks are expected to have a sig- nificant impact and have the potential for many applica- tions. Many such applications are envisioned to include a large number of small transactions, such as text messaging, paging, resource discovery, query resolution, and sensing. In such appli- cations, only a few packets are required to complete the transac- tion. Nodes in ad hoc networks are power constrained with com- munication being a major power consumer. Also, mobility cre- ates a dynamic environment in which routes frequently become invalid. Hence, it becomes very inefficient to discover optimal routes for small transactions, since the cost of such discovery is quite high, often exceeding that of the actual data transfer. Conventional routing protocols strive to provide shortest path routes. For example, in some cases, a routing protocol may use flooding to explore all possible routes, then chooses the op- Manuscript received March 15, 2003; revised September 2, 2003, May 2, 2004, August 13, 2004, and September 17, 2004. This work was supported in2004, August 13, 2004, and September 17, 2004....
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This note was uploaded on 05/27/2011 for the course CIS 4930 taught by Professor Staff during the Spring '08 term at University of Florida.

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