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With the increasing use of hand held wireless devices (tablet computers, cell phones, mobile Internet devices, PDAs etc.) and recent advancement in wireless communication technology, Mobile Ad hoc NETwork (MANET) is gaining more importance in commercial, military, public and private sectors. MANET is wireless local area network model which operates in the absence of any centralized infrastructure such as base stations or access points (Toh, 2001; Chlamtac, Conti, & Liu, 2003). It is basically a temporary infrastructureless network formed by a set of autonomous mobile nodes connected through wireless communication technology where the topology of the network changes dynamically due to which nodes in the network rapidly set up paths among themselves to transmit data. In order to provide the valid communication between two mobile nodes beyond their direct transmission range in MANETs, the intermediate nodes are used to forward the packets in multi-hop fashion as shown in Figure 1. Each node also functions as a router in MANETs.
MANETs have several salient characteristics as described below (Murthy & Manoj, 2004; Ilyas, 2010):
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Dynamic network topology
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Automated reconfiguration
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Multi-hop radio relaying
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Autonomous and infrastructureless
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Device heterogeneity
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Network scalability
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Self-creation, self-organization and self-administration
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Distributed and cooperative nature of operation
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Device size limitation
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Ease of deployment
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Minimum bandwidth usage
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Minimum human intervention to configure the network
However, before MANETs become a commonplace, following technical challenges must be overcome:
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Limited wireless transmissions range
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Unreliability of wireless links between nodes
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Very limited transmission range
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Broadcast nature of wireless medium
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Packet loss due to errors in the transmission
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Time varying wireless link characteristics
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Routing overhead
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Quality of service
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Mobility-Induced route changes
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Mobility-Induced packet losses
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Frequent network partitions
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Resource constraints
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Bandwidth and slower data transfer rate
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Fluctuating link bandwidth of wireless links
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Ease of snooping on wireless transmissions (Security Issue)
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Weaker in security due to lack of centralized management facility
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Limited physical security