A fault-tolerant protocol for energy-efficient permutation routing in wireless networks

A wireless network (WN) is a distributed system where each node is a small hand-held commodity device called a station. Wireless sensor networks have received increasing interest in recent years due to their usage in monitoring and data collection in a wide variety of environments like remote geographic locations, industrial plants, toxic locations, or even office buildings. Two of the most important issues related to a WN are their energy constraints and their potential for developing faults. A station is usually powered by a battery which cannot be recharged while on a mission. Hence, any protocol run by a WN should be energy-efficient. Moreover, it is possible that all stations deployed as part of a WN may not work perfectly. Hence, any protocol designed for a WN should work well even when some of the stations are faulty. The permutation routing problem is an abstraction of many routing problems in a wireless network. In an instance of the permutation routing problem, each of the p-stations in the network is the sender and recipient of n/p packets. The task is to route the packets to their correct destinations. We consider the permutation routing problem in a single-hop wireless network, where each station is within the transmission range of all other stations. We design a protocol for permutation routing on a WN which is both energy efficient and fault tolerant. We present both theoretical estimates and extensive simulation results to show that our protocol is efficient in terms of energy expenditure at each node even when some of the nodes are faulty. Moreover, we show that our protocol is also efficient for the unbalanced permutation routing problem when each station is the sender and recipient of an unequal number of packets.