A performance analysis of wireless sensor networks

Wireless Sensor Networks (WSNs) are expected to be the next technology to have a huge impact on society. WSNs consist of a large number of tiny sensors which integrate sensing, processing and wireless communication capabilities. Research on all aspects of WSN has been gaining momentum very rapidly in the last few years. An important issue is the choice of MAC protocol for WSN. The proposed MAC protocols may be divided into two major categories: contention and scheduling based. Contention based protocols consume more energy than scheduling based protocols because of retransmission of messages caused by collisions. However, scheduling based protocols, i.e. TDMA requires a large amount of resources because each customer is assigned a timeslot. In order to save both resources and energy, a TDMA media access protocol with slot reuse had been proposed in this work, we consider modeling of such a wireless sensor network. It is assumed that the nodes have two modes of operation, active and sleep modes. We model the sensor network as a Jackson network with node breakdowns. We determine the joint distribution of the queue lengths in the sensor network. From this result, we derive the probability distribution of the number of active nodes and blocking probability of node activation. Then, we present the mean packet delay, average sleep period of a node as well as the network throughput. The model also captures reduction in the traffic load due to elimination of redundant information in the collected data. Finally, we discuss how the derived results may be used in the design of sensor networks