An Improved Spray and Wait with Probability Choice Routing for Opportunistic Networks
Opportunistic networks are sparse multi-hop ad hoc networks in which nodes exploit any pair-wise contact opportunities to share and forward messages. The main challenge for this environment is that conventional routing schemes do not work properly.  Among the existing Opportunistic Networks routing algorithms, the epidemic routing and probabilistic  routing could provide higher delivery  probability and shorter delays, but is with a large overhead, while the spay and wait routing could reduce the overhead, but is with low delivery probability and high delay.  This paper proposes the Spray and Wait with Probability Choice (SWPC) routing, where continuous encounter time is used to describe the encounter opportunity; a delivery probability function is set up to direct the different number of copies to the destination during the spray phase; and a forwarding scheme is implemented in the wait phase. Simulation results show that proposed SWPC shows prominent superiority in the delivery rate, the average delay and the communication overhead, and adapted for the frequently disconnected opportunistic network.