Definition:
Definition:
A routing protocol in an Ad hoc network determines the path for data packets from source to destination without fixed infrastructure.
Key Issues and Challenges:
Key Issues and Challenges:
One. Dynamically Changing Topology: Nodes move freely causing frequent link changes. Routes become invalid quickly. Protocol must handle rapid topology updates efficiently.
Two. Bandwidth Constraint: Wireless links have limited and shared bandwidth. Control packets for routing consume useful bandwidth. Protocol must minimize overhead.
Three. Error-Prone Shared Broadcast Radio Channel: Wireless signals face interference, fading, hidden terminal problem. Packet loss is higher than wired networks.
Four. Hidden Terminal Problem: Node A and C cannot hear each other but both send to B, causing collision. CSMA/CA with RTS/CTS partially solves this.
Five. Energy Constrained Operation: Nodes run on batteries. Routing protocol must be energy-aware. Minimize transmissions to extend network lifetime.
Six. Limited Physical Security: Ad hoc networks are more vulnerable to attacks (eavesdropping, spoofing, DoS). Secure routing is difficult without infrastructure.
Seven. Scalability: As number of nodes increases, routing table size, control overhead, and convergence time also increase. Protocol must scale well.
Eight. Uni-directional Links: Due to different transmission power levels, some links may be one-way. Most routing protocols assume bidirectional links.
Nine. QoS Support: Hard to guarantee Quality of Service (delay, bandwidth, reliability) due to dynamic topology and shared medium.
Ten. Interoperability: Multiple nodes from different vendors need to communicate. Standard protocols must be followed.