GPSR, or Greedy Perimeter Stateless Routing, is a routing protocol typically used in wireless networks, especially in environments where network topology changes frequently, like in mobile ad hoc networks (MANETs). The main aim of GPSR is to efficiently guide data packets from the source to the destination using geographic positions of the devices involved.
Here’s how GPSR works at a basic level:
Greedy Forwarding: Initially, the protocol tries to forward packets using greedy forwarding. This means it will always try to send data to the neighboring device that is geographically closest to the destination. The idea is simple—by always moving closer to the destination, the data is likely to get there faster.
Perimeter Routing: There are situations where greedy forwarding might fail, particularly when packets are stuck in a “local minimum” or void—where there’s no neighbor closer to the destination than the current node. In such scenarios, GPSR shifts to perimeter routing. This involves navigating around the perimeter of the void using a method called the “right-hand rule,” essentially skirting the obstacle until the packet can resume greedy forwarding.
Statelessness: Unlike other routing protocols that maintain state information about the entire network, GPSR only relies on information about immediate neighbors. This statelessness significantly reduces the memory and processing power needed on each device.
GPSR is advantageous due to its scalability and efficiency in dynamic network scenarios. It adapts well to frequently changing network topologies, minimizes overhead, and utilizes geographic information to make efficient routing decisions. However, the protocol assumes that devices know their own location and that routing is based on static geographic positions, which might not be suitable for every application or environment.