Real-Time Routing Protocol Based on Expect Grids for Mobile Sinks in Wireless Sensor Networks

Real-time data delivery is the most important requirement for mission-critical applications in wireless sensor networks. Since a mobile sink is requested for applications and for energy efficiency in WSNs, an Expect Area-based Real-time Routing protocol (EAR2) is proposed to support real-time routing to the mobile sink. EAR2 is based on an Expect Area (EA) of the mobile sink and exploit flooding of real-time data within EA. However, flooding within EA makes sensor nodes in EA consume much energy. Flooding time within EA may also be difficult to measure and change widely according to time and environment. Thus, to avoid the flooding problems in EAR2, we propose a new real-time routing protocol based on grids for a mobile sink. In addition to EA of a mobile sink, the proposed protocol considers Expect Grids (EGs) of the mobile sink, which are included in EA. Instead of flooding within EA, the proposed protocol exploits multicasting to EGs and one-hop forwarding in a EG because in comparison with flooding, multicasting saves much energy and one-hop forwarding time is easy to measure and changes narrowly according to time and environment. Simulation results show that the proposed protocol is superior to other protocols.