Multi-state reliability and message time delay in wireless sensor networks

Reliability is an important parameter to measure the function of a wireless sensor network (WSN). In this paper, we consider a multi-state reliability model and message time delay problems in WSNs. The message time delay between target nodes and the sink node is an important factor to measure the reliability of WSNs. By defining the expected time delay for the message transmission, we further consider the multi-state reliability as the probability that there is at least one message which can be received by the sink node within the time period ?. Furthermore, an integer programming method is used to compute the multi-state reliability. Finally, examples are used to show the effectiveness of the proposed method.