End-to-End Delay Measurement in Wireless Sensor Networks without Synchronization

The deployment of large scale Wireless Sensor Networks generally needs network management and measurement solutions. End-to-end delay is one of the most important metrics in assessing the network performance. Many efforts have been devoted to measuring the end-to-end delay efficiently and precisely. Unfortunately, existing approaches often require sensor nodes to be tightly time synchronized which is costly in resource limited sensor network. We propose a novel scheme that can measure the end-to-end delay for each packet to the granularity of tens of microseconds without clock synchronization. Through extensive experiments on our testbed, we examine the effectiveness of our approach. The results show that our scheme achieves high performance with low overhead. We also present observations about the network states by tracking and analyzing the end-to-end delay data.