International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.2, Issue.6, Nov-Dec. 2012 pp-4122-4127 ISSN: 2249-6645 www.ijmer.com 4122 | Page M.Chithik Raja Department of Information Technology Salalah College of Technology Sultanate of OMAN ABSTRACT:Many routing protocols have been proposed to facilitate data transport from sensor nodes to a base station; few of these protocols have been formally verified or operationally deployed however. The Minimum Cost Forwarding (MCF) routing protocol in MAC layer, has been proposed. The application of MCF is restricted to networks possessing a single sink node and multiple source nodes. However, it offers several potential advantages for sensor nodes with limited resources. The MCF protocol is the subject of the current study with a view to its implementation in a prototype sensor network. The first phase of the work, and the subject of this paper, is the formal evaluation of the MCF protocol to increase confidence in its correctness and study its ability to handle node failure and other errors. As a result of formal verification using a model checking tool, UPPAAL, we confirm the soundness of the protocol during its initialization and operational phases and we have identified significant weaknesses in the published protocol concerning equal-cost minimum cost paths and node failure. In particular, we identify a flaw in the previously suggested periodic initialization broadcast to reestablish a minimum cost field. Here we present these results and offer improvements to overcome some deficiencies. It is expected that model checking may usefully be applied in the study of other WSN protocols. I. INTRODUCTION Sensor networks have been researched and deployed for decades; their wireless extension, however, has witnessed a tremendous upsurge in recent years. This is mainly attributed to the unprecedented operating conditions of wireless sensor networks (WSNs). As of today, a major problem in deploying WSNs is their dependence on limited battery power. A main design criterion is to extend the lifetime of the network without jeopardizing reliable and efficient communications from sensor nodes to other nodes as well as data sinks. A prominent example of today’s non -optimized WSN deployment experiences is that the start-up alone costs the network a third of its battery power [1][2]. Optimizing every facet of the communication protocols is therefore vital and imperative. Such stringent design requirements can be met by a plethora of approaches, e.g. using cross-layer design paradigms, collaborative protocols, etc. This has led to copious novel distributed signal processing algorithms, energy-efficient medium access control and fault-tolerant routing protocols, self-organizing and self-healing sensor network mechanisms, reliable data aggregation algorithms, etc. These solutions stipulated first commercial activities as well as standardization approaches, including WOSA [3], KNX [4], IEEE 802.15.4 [5], IETF 6LowPan [6], IETF ROLL [7], etc. Wireless sensor networks (WSN) consist of small self contained devices with computational, sensing and wireless communication capabilities. When deployed, they allow flexible, powerful, tether-less, automated data monitoring and/or control systems to be created. A sensor network comprises a set of sensor nodes and one or more base stations. The sensors generate, process and forward data via intermediate nodes to the base stations. Anticipated applications include environmental hazard monitoring, forest fire detection, machine instrumentation, etc. SensorNetworking has received considerable attention in recent years and many routing protocols have been proposed to facilitate data transport over such networks. Our current work[4] is based on the Minimum Cost Forwarding (MCF) network routing protocol in MAC layer with the view to its implementation in a prototype sensor network. The first phase of the work, and the subject of this paper, is the formal evaluation of the MCF protocol to increase confidence in its correctness and study its ability to handle node failure and other errors in MAC Protocol. MCF is considered particularly appropriate for sensor networks possessing limited resources since it does not require the storage of routing tables at sensor nodes, it establishes optimal routing paths with few message exchanges and it is scalable and simple to implement. The MCF protocol adopts a so-called flat model in which nodes have equal status except for a single base station, i.e. there is no hierarchy amongst the nodes. All message traffic generated at sensor nodes is routed towards a base station by forwarding along minimum cost paths comprising one or more sensor nodes. The minimal cost path field is established during an initialization phase after which message traffic may commence. We describe in this paper how the MCF routing protocol may be formally modeled as a set of timed automata. The models are amenable to a formal analysis to verify that they possess some well-defined properties. Our aim is to investigate if MCF can successfully establish a minimum cost field and that data generated periodically at sensor nodes is communicated to a base station. Additionally we study the problems of node failure and equal-cost paths which compromise the effectiveness of MCF. Our focus is not merely to restatethe MCF protocol but to present a formal verification of its behavior and to identify some of its operational difficulties. The remainder of this paper is organized as follows. In Section II, we describe the operation of the Minimum Cost Forwarding protocol. We present the algorithms used to establish a minimum cost field over a group of sensor nodes and to forward frames generated in sensor nodes to a base station. The Minimum Cost Forwarding Using MAC Protocol for Wireless Sensor Networks