Causal Order Protocol Based on Virtual Synchronous Group Membership in Wireless Sensor Networks

Abstract

Many distributed applications require cooperating to fuse their data in those WSNs in real time. Some of these WSNs allow interacting with publishers and subscribers (P/S) sensors. But, there exist little research works on development of causal ordering based on virtual synchronous group membership of these P/S systems, one of mandatory properties for this kind of application fields. In this paper, we propose a novel approach based on gossip protocols and virtual synchronous group membership, guaranteeing the causal message ordering in those WSNs. In the proposed protocol, a broker gossips about FLUSH including the whole set of vectors to subscribers for virtual synchronous group membership. The protocol does not end based on the acknowledgement of FLUSH, but on the maximum gossip rounds of gossip disseminations. Therefore, this protocol is appropriate for sensor networks configured with active and passive sensors in real time synchronization. Its features might result in very low cost communication overhead between brokers and subscribers with flexible consistency by cooperating to fuse their data. Simulation results show that our gossip-style dissemination protocol outperforms the previous one in terms of virtual synchronous group membership.