MANETs

Mobile ad hoc networks (MANETs) are self-configuring, infrastructure-less networks of mobile devices connected by wireless links. Each node in a MANET participates in routing by forwarding data for other nodes, acting as both host and router. Because nodes are mobile, the network topology changes frequently and unpredictably. There is no fixed infrastructure such as access points or base stations; nodes rely on multihop wireless communication to relay packets.

Key characteristics include dynamic topology, decentralized management, power-constrained devices, wireless bandwidth limits, and cooperative routing. Security is a particular challenge due to the open wireless medium and lack of centralized control.

Routing in MANETs is typically achieved through multi-hop paths and can be categorized into proactive (table-driven) protocols like DSDV and OLSR, reactive (on-demand) protocols like AODV and DSR, and hybrid approaches like ZRP. These protocols balance overhead and rapid route discovery against mobility.

Applications include military communications, disaster response and emergency networks, temporary or remote deployments, sensor networks, and vehicle-to-vehicle or vehicular networks.

Challenges include scalability to large networks, energy efficiency, interference and wireless contention, quality of service, reliable routing under mobility, IP addressing and naming, and security threats such as spoofing and route manipulation. Security measures encompass encryption, authentication, secure routing, and trust management, often with cross-layer design.

Performance is evaluated using metrics such as packet delivery ratio, end-to-end delay, throughput, routing overhead, and energy consumption. Simulation and emulation tools commonly used include ns-2/ns-3, QualNet, and OMNeT++, along with mobility models reflecting realistic movement patterns.

Research continues to improve scalability, reliability, security, and interoperability with emerging network paradigms and applications.