K- Fault Tolerant in Mobile Adhoc Network under Cost Constraint Mrs. Sugandha Singh Dr. Navin Rajpal Professor & Head, Computer Science and Engineering Professor, Information Technology, USIT Jodhpur Institute of Engineering and Technology, JIET Guru Gobind Singh Indraprastha University, Jodhpur, INDIA Delhi, INDIA sugandha06@gmail.com navin_rajpal@yahoo.com Dr. Ashok Kale Sharma Dean, Young Men Christian Association University YMCA, University Faridabad, INDIA ashokkale2@rediffmail.com ABSTRACT— A network topology is K-FT topology if it can endure K number of link failures. however to find a reliable hardware topology for a set of nodes keeping the total cost of the links within a predefined budget, is a challenging task, especially when the topology is subjective to constraints that the topological network can tolerate K link failures keeping total cost of network within budget. This problem has been addressed in this paper where in a novel algorithm is proposed that uses N X N matrix to represent the cost between the participating nodes, and uses K-FT topology to tackle the fault tolerant problem of Mobile Adhoc Networks. Intention is to achieve optimal resource utilization and fairness among competing end to end flows. A network topology is said to be K-FT if and only if every pair of node is reachable from all other nodes for K link failures. The algorithm has been tested for wide range of node sets and the result obtained there of suggest that the proposed algorithm finds better solutions in comparison to Genetic Algorithm. Index Terms: Link failure, Fault tolerance, K-FT topology, Mobile Adhoc network. I. INTRODUCTION An important design constraint for any reliable mobile adhoc network for distributed computing is that the network must remain connected even on failure of one or more links. Usually the design of network layout is subject to the cost constraints as well as the reliability requirements to cope with the fault occurred in the network. Compared with wired networks where flows only contend at the router that performs flow scheduling, the unique characteristics of multi-hop wireless networks show that flows also compete for shared channel if they are within the interference ranges of each other. This presents the problem of designing a topology-aware resource allocation algorithm that is both optimal with respect to resource utilization and fair across contending multi-hop flows. Resource allocation in such networks needs to address both fairness and overall network performance. Pricing is a prospective direction to regulate behaviors of individual nodes while providing incentives for cooperation. Some pricing strategies for resource allocation have been developed by taking account of factors like multiple transmission rates and energy consumption of nodes [1]. Multi-rate transmission capability is commonly seen in most wireless products nowadays, while energy is one of the most important resources in portable so system takes into account energy consumptions in the transmitter side, the receiver side, and those that are non-transmitters and non-receivers but are interfered by these activities. So necessity is to more accurately reflect the real energy constraint in a wireless network. Due to the decentralized and self-organizing nature of ad hoc networks, the quest for a fully distributed and adaptive algorithm further exacerbates the problem. This paper concentrates on two constraints that is cost and fault tolerance, to obtain an outline of a Mobile Adhoc Network with a possible minimum cost. For simplicity it has been assumed; that all the links have the same reliability. Though in reality this range is in between 0 and 1 (0<r ij <1) where r ij is the reliability of the link between node i and node j. In this paper, an algorithm for designing a Mobile Adhoc Network with possible minimum cost has been developed. Through simulation it has been shown that the proposed algorithm can efficiently find out an optimal solution for the above defined problem. The paper is organized as follows. Section II defines related work, Section III illustrates the problem. An overview of the genetic algorithm is given in section IV. Section V includes the proposed algorithm henceforth stated as Algorithm-ANS. The comparative results of the genetic algorithm and Algorithm-ANS on three sets of synthetic data is given in section VI. Section VII concludes the paper. II. RELATED WORK In previous work, fair packet scheduling mechanism have been proposed [1], [2], [3] and shown to perform effectively in providing fair shares among single-hop flows in wireless ad hoc networks, and in balancing the trade-off between fairness and resource utilization. A number of approaches to topological network optimization have been developed [4], [5], [6] & [7] are considered the topological optimization of communication networks subject to reliability constraints. In [8] the author presents a decomposition approach to the problem in which considering the reliability constraint the total network cost is minimized. Unfortunately, there exist fundamental 368 ___________________________________ 978-1- 4244 -8679-3/ 11/$26.00 ©2011 IEEE