Real-time Routing for Mobile Sensor/Actor Networks

With the increasing interest in the application of wireless ad hoc networks, the demand for providing QoS in such applications also grows. Particularly, in sensor and actor networks, providing certain delay bounds is crucial for the actors as they perform their actions based on the received data from sensors. The usefulness of the content from sensors is based on its timeliness. In this paper, we present Ad Hoc On Demand Delay Constrained Distance Vector Routing (AOD(2)V) which is an extension to the widely used routing protocol AODV for providing delay constrained data delivery in mobile sensor/actor networks. The admission control is based on Delay-EDD scheduling algorithm. The idea is to reserve the resources while routes are being determined in the route discovery phase of AODV. The reservation considers the service time at each node till the destination node. As long as the cumulative delay which is received at the destination is less than the desired delay bound, a positive acknowledgment is sent back to all the nodes on the path with AODV's route reply packet and the connection request is admitted. Otherwise, the connection request is rejected and the reserved resources at the intermediate nodes are released. When the data transmission starts, Earliest Deadline First (EDF) scheduling algorithm is used to determine the departure order of the packets at the intermediate nodes. The performance of AOD(2)V is validated through extensive simulations and has been shown to outperform AODV in terms of delay and data delivery ratio without introducing any major extra overhead.