Research Of On-demand Monitoring Technology For Wireless Sensor Networks

Passive monitoring is a technology that tries to capture network packets of awireless sensor network by deploying a few sniffers. The captured packets can beanalyzed to recover transmission delay and other network performance indicators,which are used for designing better protocols for wireless sensor networks.The accuracy of network delay and other performance indicators highly relies onwhether enough packets have been captured during passive monitoring. If too manypackets are lost, the performance indicators may be quite different with ground truth.In this paper, we try to enhance the passive monitoring technology to achieve the mostcaptured packets with a given number of sniffers.We show that current passive monitoring technologies have not done enough onsniffer placement and channel assignment. First, the sniffer placement mechanismonly achieves node level covering. The difference of transmission demands amongsensor nodes has not been taken into account. Thus, packet level covering has notbeen achieved. Second, sniffers change their channels only between two long timewindows. The channel switch mechanism fails to cover transmissions that com fromdifferent channels in a short while.We propose the on-demand passive monitoring technology, which is anenhancement of current passive monitoring technologies, withnew sniffer placementand channel assignment mechanisms. The so called on-demand passive monitoringconsists of two processes. First, we try to sense transmission demands, which are alsomonitoring demands. Second, sniffer placement and channel assignment are doneaccording to the sensed demands.Specifically, we propose the following two mechanisms of the on-demandpassive monitoring technology.First, we propose the on-demand sniffer placement mechanism. To sensemonitoring demands of different nodes, we deploy a part of sniffers with a node levelcover algorithm. Then we deploy more sniffers for nodes with lots of demands or notwell covered previously. In this way, we achieve packet level cover in snifferplacement..Second, we propose the on-demand channel assignment mechanism. In this mechanism, sniffer channels are assigned with respect to the previously senseddemands that come from captured packets. In this way, sniffer can be reused onmultiple channels.Simulations show that compared with current passive monitoring technologies,the on-demand passive monitoring we propose achieves higher packet capture rates.Thus, on-demand passive monitoring can accurately recover transmission delay andother performance indicators.