Opportunistic data forwarding has drawn much attention in the research community of multihop wireless networking, with most research conducted for stationary wireless networks. One of the reasons why opportunistic data forwarding has not been widely utilized in mobile ad hoc networks (MANETs) is the lack of an efficient lightweight proactive routing scheme with strong source routing capability.
In this paper, we propose a lightweight proactive source routing (PSR) protocol. A lightweight proactive source routing (PSR) protocol to facilitate opportunistic data forwarding in MANETs PSR, each node maintains a breadth-first search spanning tree of the network rooted at it. This information is periodically exchanged among neighboring nodes for updated network topology information. Thus, PSR allows a node to have full-path information to all other nodes in the network, although the communication cost is only linear to the number of the nodes.
This allows it to support both source routing and conventional IP forwarding.Our tests using computer simulation in Network Simulator 2 (ns-2) indicate that the overhead in PSR is only a fraction of the overhead of these baseline protocols, and PSR yields similar or better data transportation performance than these baseline protocols. PSR A Lightweight Proactive Source Routing Protocol For Mobile Ad Hoc Networks
Every incoming packet is sent out on every other link by every router. Super simple to implement, but generates lots of redundant packets. Interesting to note that all routes are discovered, including the optimal one, so this is robust and high performance (best path is found without being known ahead of time). Some means of controlling the expansion of packets is needed. It could try to ensure that each router only floods any given packet once. Could try to be a little more selective about what is forwarded and where. The station initiating a packet stores the distance of the destination in the submitted packet (or the largest distance in the network). Each node reduces the counter by one, and resubmits the packet to all the adjacent nodes (but not to the node from where it received the packet). Packets with counter 0 are discarded. The destination node doesn’t resubmit the packet.
We proposed in this paper uses tree-based routing as in PFA and WRP. To make our PSR more suitable for the MANETs, we adopt a combined route update strategy that takes advantage of both “event-driven” and “timer-driven” approaches.
Specifically, nodes would hold their broadcast after receiving a route update for a period of time. If more updates have been received in this window, all updates are consolidated before triggering one broadcast. The period of the update cycle is an important parameter in PSR. Furthermore, we go an extra mile to reduce its routing overhead.
First, we interleave fulldump and differential updates to strike the balance between efficient and robust network operation. Second, we package affected links into forests to avoid duplicating nodes in the data structure. Finally, to further reduce the size of differential update messages, each node tries to minimize the alteration of the routing tree that it maintains as the network changes its structure