Summary: ExOR: Opportunistic Multi-Hop Routing for Wireless Networks
The paper proposes a new protocol ExOR providing MAC and routing functionality for over
wireless networks which provides the benefits of diversity routing on conventional radio
hardware. The protocol results in increased end-to-end throughput and better network
utilization over multi-hop wireless networks.
The basic technique proposed in the paper is to use hop-by-hop routing selection for packets.
The sender broadcasts a batch of packets to the nodes with a list of forwarding nodes in
priority. Each of the nodes who hear the transmission and are in the list buffer the batch of
packets. Next, the highest priority forwarding node broadcasts the packet along with its batch
map indicating the fragments it received and is thus able to forward. The remaining packets
are then forwarded by subsequent lower priority nodes until 90% of packets are transmitted,
the remaining are then transmitted using traditional routing.
The authors provide results of experiments performed on Roofnet. The results indicate that
the effectivenes of ExOR increases with the number of hops. With single hops, ExOR achieves
about 35% increase in throughput which is due to reduced resends when ACKs are lost in
traditional routing. With multiple hops, ExOR provides 2 to 4 times more throughput.
ExOR provides dynamism in routing at each hop which can better react to variations
ExOR enables the use of opportunistic scenarios where reception of packets is highly