Research On Latency And MAC Protocol For The Wireless Sensor Networks

As an emerging technology, wireless sensor network(WSN) is widely studied andithasencounteredmanychallenges,ofwhichhowtoallocatethespectrumwithinnodesis a quite important one to resolve the problems to improve the network performanceof the wireless sensor networks. Meanwhile, as the development of the cognitive radiotechnology, in order to mitigate the limited spectrum resources, the cognitive radiosensor network has become a new research direction in the wireless communicationarea. And the research of the cognitive radio MAC protocol is a hot topic in this feld.This thesis gives a theoretical model of the latency for the message dissemination inlarge-scale wireless sensor network and proposes a cluster-based MAC protocol for thecognitive radio sensor network.This thesis frst studies the message dissemination in large-scale wireless sen-sor network. Because of the sensor node’s active/dormant schedule and the unreliablelinks,themessagedisseminationinlarge-scalesensornetworksmeetquiteagreatchal-lenge. To better study about the message dissemination, we provide a theoretical mod-el of the latency for the message dissemination, which provides the lower and upperbounds on the latency. With the help of the model, we can evaluate the performanceof any solutions to the dissemination in large scale sensor networks. Using the boundsof the theoretical model, we also propose the NANC algorithm to achieve better gainson latency. Our simulation shows that the NANC can perform well and is much closerto the lower bound of the theoretical model.Then this thesis proposes a cluster-based CRSN MAC protocol (KoN-MAC) forthe multi-hop cognitive radio wireless sensor networks. We frst design a mediumaccess scheme for nodes in every cluster to supply a contention free communication, whichisspecifedforthemulti-hopandmulti-channelWSN.Then,wedesignachannel-sensing scheme to lower the energy consumed in transmitting a packet, which is basedon the fact that the CR sensor nodes will consume higher energy if CR sensor nodessense more channels. Our proposed scheme makes CR sensor nodes just sense few-er channels to get the available channels. We model and analysis mathematically ourscheme, and evaluate the performance using NS-2. The evaluation shows that our pro-posed KoN-MAC can achieve better energy gains as well as higher throughput, lessdelay and lower packet loss.