Wireless sensor networks are networks of large quantities of compact micro-sensors with wireless communication capability. Innovative techniques that improve energy efficiency to prolong the network lifetime are highly required. Clustering is an efficient mechanism to increase the network scalability and lifetime. There is lot of challenges, in which one is to use efficiently limited energy provided. In this paper, we propose an efficient technique in which cluster head is dynamically selected from the cluster of cluster heads within the cluster. Within the cluster multiple cluster heads are selected and after certain rounds, when energy level becomes less than or equals to normal nodes within the clusters, normal nodes will take the charge and to become cluster heads. The mastership of cluster heads rotates continuously, makes the network without halt. It will make the sensor nodes to use their energies efficiently and increase the overall network lifetime.
With rapid advances in Personal Area Networks (PAN), the last decade has witnessed a growing demand for Wireless Devices and its Applications. However fixed spectrum assignment policies from ISM bands become inefficient, because of under-utilization of licensed spectrum for all time. To overcome spectrum requirements for PAN better strategies may need to dynamically utilize radio spectrum aimed to meet higher throughput parameters, QoS requirements as well as mobility and Cognitive Radio (CR) Technology can propose solutions in this direction. Whereas numerous challenges are involved in this direction over heterogeneous parameters such as MAC layer, Routing issues, Security issues, etc. Moreover with this influence, revision may need over upper layer protocols. Finally, at dense population areas, at present new direction Cognitive Radio Personal Area Networks (CR-PAN) may recommend over smart devices without predefined infrastructure, to gain an increased traffic performance over mobility and availability through CR, where users independently determine their own spectrum operating parameters widely at threshold level.
We study the impact of heterogeneity of energy in hierarchically clustered wireless sensor networks. Heterogeneity in energy of the sensor nodes can be because of (i) differences in transmission levels of sensor nodes, (ii) differences in initial energies, or (iii) due to introduction of high energy sensor nodes within the sensor network to revitalize it [11]. Clustering protocols divide sensor nodes into groups of member nodes called clusters. Each cluster contains a cluster head. Cluster heads form an independent dominating set. We identify a potential drawback of such a scheme in heterogeneous sensor networks. In a heterogeneous sensor network, electing sensor nodes with high energy (called advanced nodes) which lie within the same transmission radius may be better than electing a single advanced node as cluster head. Cluster heads expend more energy than member nodes during each round. Therefore, election of advanced nodes as cluster heads becomes imperative for the performance of the sensor network. We propose a weighted cluster head election scheme, called Weight Based Clustering for Heterogeneous sensor Networks (WBCHN). WBCHN prolongs the stability period (time before the first node dies) through the election of high percentage of advanced sensor nodes as cluster heads.
In WSN cluster-based routing approach is a major step in the direction of energy efficiency. However, research shows that energy dissipation in a cluster-based approach predominantly occurs in two cases; first during data transmission to the base station and second during data fusion/aggregation. Eventually, this leads to sizable energy dissipation, the early death of CHs and results in lower network lifetime. Moreover, in most of the recent proposed works, it is never assured that an individual node selected as a Cluster-Head would perform all the assigned tasks without dying in the process. Thus to address these problems, a new approach is proposed in this paper, where two cluster-heads (CHs) in every cluster are selected; first cluster-head being used for data aggregation (Primary-CH) and second for data transmission (Secondary-CH), which assists in reducing the burden of a single Cluster Head. Along with the dual Cluster-Heads, another key feature adopted in this paper is the Energy Threshold values for PCH and SCH. These Energy Thresholds for different CHs calculates the minimum energy required by a node to perform all the tasks assigned to it when elected as CH. So, while electing Primary Cluster-Head (PCH) and Secondary Cluster-Head (SCH) along with other criterions energy threshold values for PCH (EPO) and energy threshold values for SCH (ESO) are also used. Any node with remaining energy less than that of energy thresholds would never be considered for Cluster-Heads. Therefore, by employing the above-mentioned criterions, this article proposes a new protocol that uses dual heads and assists in enhancing the network life of a network as compared to LEACH protocol.
This work details a new class of energy efficient and delay bounded data gathering framework viz. generalized intra cluster chaining (GICC) framework for large scale wireless sensor network. The framework extracts the advantages of both purely cluster based and purely chain based data gathering schemes for wireless sensor network without compromising with their drawbacks. Detailed analysis and simulation results reveals GICC increases the performance of any purely cluster based protocols by 60-70% and also utilizing only localized information increases the network lifetime comparable with optimal results. GICC framework also tends to decrease information loss due to in-network aggregation, delays in in-network packet forwarding and is practically applicable to all kinds of wireless sensor network.
It is necessary to authenticate users who attempt to access resources in Wireless Local Area Networks (WLANs). Extensible Authentication Protocol (EAP) is an authentication framework widely used in WLANs. We designed a noble method that uses the concept of dynamic key to eliminate the redundant use of session keys which in turn enhances encryption capabilities and reduces computation time. Extensive analysis shows that our scheme efficiently withstands all the security threats reported in RFC 4017. We also demonstrate the effectiveness of our framework to mitigate a broad range of known attacks recently reported in literature.
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