Reliability and Feedback of Multiple Hop Wireless Networks

This paper analyzes fault-tolerance over the entire design life of a class of multiple-hop wireless networks, where cooperative transmission schemes are used. The networks are subject to both node failure and random channel fading. A node lifetime distribution is modeled with an increasing failure rate, where the node power consumption level enters the parameters of the distribution. A method for assessing both link and network reliabilities projected at the networks design life is developed. Link reliability is enhanced through use of redundant nodes. The number of redundant nodes is restricted by the cooperative transmission scheme used. The link reliability is then used to establish a re-transmission control policy that minimizes an expected cost involving power, bandwidth expenditures, and packet loss. The benefit and cost of feedback in network operations are examined. The results of a simulation study under specific node processing times are presented. The study quantifies the effect of loop closure frequency, acknowledgment deadline, and nodes storage capacity on the performance of the network in terms of network lifetime, packet loss rate, and false alarm rate. The study concludes that in a network where energy is severely constrained, feedback must be applied judiciously.