The Research Of Wireless Sensor Networks Clustering And Node Sleeping-scheduling

Wireless sensor network (WSN) is a new technology which includes the sensor, computer network, and micro electro-mechanical technology. The energy of sensors is limited, thus how to use energy effectively to maximize network lifetime is the principal question. Furthermore, building trust among sensors to represent malicious behavior is a problem that calls for immediate solution. This paper analyzes the design objective of WSNs routing protocols and several typical protocols. The routing protocols and sleeping schedules are studied from two aspects of clustering and trust. The main work includes as follows.1. In terms of extending the network lifetime, a LCDC algorithm is presented. Firstly, the process of clustering in LEACH is recognized and decomposed. It is pointed out that the prime reason in the delay of clustering time is the asymmetry of cluster density. Then, the cluster density are adjusted adaptively by cluster division and mergence according to the threshold of intra-cluster nodes number so as to prevent the cluster density that is not too high or too low. By-election of cluster head (CH) is proposed to handle the accidental nodes hardware failures. The network level power control is also proposed. J-Sim simulations demonstrate the proposed method could prolong network lifetime.2. In terms of sleeping schedule based on trust management, a game model of time slot assignment with trust incentives is presented. Firstly, the nonzero-sum game between CH and malicious node (MN) is analyzed according to the utility matrix. It is pointed out that Nash equilibrium (NE) could be the punishment for preventing the MN from deviation of lucrative strategy. Then, the necessary and sufficient condition for the Nash reversion to be a subgame perfect NE is proved. The single round NE exerts the punishment to the deviant of corporate strategy so as to engender cooperative effect in indefinitely repeated game. Simulations prove the decision could increase the network gains and constrain the malicious behavior.3. In terms of utilizing sleeping schedule to collect trust feedbacks for trust management, the GTFC algorithm is presented. Firstly, the sleeping scheduling of TDMA is analyzed. It is pointed out that insufficient trust feedbacks is caused by the stringent asynchronous awakening. Then sleeping scheduling is adjusted to increase the quantity of feedback collection according to gamma distribution based k coverage so as to prevent the blind zone of trust feedback collection because of asynchronous awakening. Simulations prove the algorithm could increase the quantity of the trust feedback and energy efficiency.