COUPON: Cooperatively building sensing maps in mobile opportunistic networks

With the popularity and advancements of smartphones, mobile users can sense the city using variety of sensors opportunistically, and forward the sensory data to the monitoring center for building sensing maps through intermittent connections with short-range communications. In order to build sensing maps satisfying specific sensing quality with low delay and energy consumption, we design COUPON, a novel cooperative sensing and data forwarding framework. We first notice that cooperative sensing scheme can eliminate sampling redundancy and hence save energy. Then we design two cooperative forwarding schemes by leveraging data fusion: Epidemic Routing with Fusion (ERF) and Binary Spray-and-Wait with Fusion (BSWF). Different from previous work assuming that all packets are propagated individually, we consider that packets are spatial-temporal correlated in the forwarding process, and derive the dissemination law of correlated packets. We theoretically prove that our cooperative forwarding schemes can achieve better tradeoff between delivery delay and transmission overhead. We evaluate our proposed framework and schemes with real mobile traces. Extensive simulations demonstrate that the cooperative sensing scheme can reduce the number of samplings by 93% compared with the non-cooperative scheme, ERF can reduce the transmission overhead by 78% compared with Epidemic Routing (ER), BSWF can increase the delivery ratio by 16%, and reduce the delivery delay and transmission overhead by 5% and 32% respectively, compared with Binary Spray-and-Wait (BSW).