Energy-efficient Cover In Broadcasting And Sleep-scheduling Algorithm Of Wireless Sensor Network

Wireless sensor network can be widely used in the military and civil application; it is a hot research spot. For the node's battery is limited, energy-saving drawns a lot of attention from the academic. Reducing the energy consumption in the RF module is the key to save energy. In the transmitting mode, RF module energy consumption is the highest, while in sleep mode, it consumes least energy. So reducing redundant communication and scheduling the redundant nodes to sleep can reduce energy consumption. Broadcasting is frequently used in the sensor network, its application includs data inquery, time synchronization, route etc., broadcasting communication is a important part of the total communication. Because nodes are distributed with large density, so large redundant broadcasting exists. For the same reason, only little portion of the total nodes is needed to keep active to monitor an area. So reducing redundant broadcasting and keeping the redundant nodes sleeping can reduce energy. Then how to reduce redundant broadcasting and finding redundant nodes is the key problem, it comes down to energy-efficient coverage problem. It includes two sub problems. 1. energy-efficient coverage in broadcasting: How to cover all the nodes with least nodes that if these nodes join broadcasting, then all the nodes can receive the broadcasting message. This is a minimum set cover problem that how to find a minimum CDS (connected dominating set) of total nodes. 2. energy-efficient coverage in sleep-scheduling: How to cover all the sensing area with least nodes that no blind-point exists and connectivity is kept. It is minimum-area cover problem; its key point is coverage and connectivity. The two minimum cover problem are NP-HARD all. So we can calculate the near-optimum solution with heuristic algorithm. Based on the upper analysis, we mainly analyse the CDS algorithm and redundant nodes judging algorithm, and its implementation in the broadcasting and sleep-scheduling. This thesis is supported by NSFC project: wireless multimedia technology based on the media property (60202005). The inovations of this theis are shown below: 1. Proposing a CDS parrel-alogorithm based on multi-point coverage and applying it in the broadcasting: Comparing with the congeneric algorithm, it reduce the computation complexity form ο( ?3) to ο( ?2), the mark ? denotes the maximum degree in the network. It reduces the size of the CDS and redundant broadcasting traffic. 2. Proposing a CDS serial-alogorithm based on serial maximum-independent-set coverage and applying it in the broadcasting: Comparing with the serial algorith, it can build a CDS with upper-limit. Comparing with the congeneric algorithm, it reduces the computation complexity form ο( n?)or ο( nlogn)to ο(n) , the mark n denotes the total number of the nodes in the network. The CDS size and communication complexity precedeant the congeneric algorithm a little. 3. Proposing a redundant nodes judging alogorithm based on local-perimeter coverage and applying it in the sleep-scheduling: Comparing with the congeneric algorithm, it reduce the communication overhead and computation complexity, and this algorithm need no location information. We design a sleeping-schedule algorithm, it balance the energy consumption in the network by including the existing energy in the random timeout timer.