Jong-Myoung Kim

In designing the wireless sensor networks, the energy is the most important consideration because the lifetime of the sensor node is limited by the battery of it. To overcome this demerit many research have been done. The clustering is the one of the representative approaches. In the clustering, the cluster heads gather data from nodes, aggregate it and send the information to the base station. In this way, the sensor nodes can reduce communication overheads that may be generated if each sensor node reports sensed data to the base station independently. LEACH is one of the most famous clustering mechanisms. It elects a cluster head based on probability model. This approach may reduce the network lifetime because LEACH does not consider the distribution of sensor nodes and the energy remains of each node. However, using the location and the energy information in the clustering can generate big overheads. In this paper we introduce CHEF - cluster head election mechanism using fuzzy logic. By using fuzzy logic, collecting and calculating overheads can be reduced and finally the lifetime of the sensor networks can be prolonged. To prove efficiency of CHEF, we simulated CHEF compared with LEACH using the matlab. Our simulation results show that CHEF is about 22.7% more efficient than LEACH.

Wireless sensor networks (WSNs) consist of small sensor nodes with constrained energy, memory and computation capabilities. They are often deployed in the unattended and hostile environment. Therefore sensor nodes are vulnerable to attacks such as node capture and collusion attack by adversaries. To protect the whole network, cryptographic techniques are necessary that pairwise key establishment is the essential procedure. It enables that sensor nodes can communicate to each other securely. However, it is impractical to use traditional key management techniques such as public key cryptography and key distribution center (KDC) because of the resource constraints of sensor nodes. This paper proposes a key distribution scheme, based on exclusion-based systems (EBSs) and t-degree bivariate polynomials. It is an energy-efficient dynamic key management scheme which performs localized rekeying to minimize overhead.