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This paper deals with information discovery and aggregation in large scale wireless sensor networks applied for mission-critical applications like military reconnaissance. To support query processing based on the gathered information, an efficient and reliable information discovery mechanism is proposed for sensor networks. We extend the basic Comb-Needle Discovery Support Model [3] by including Cluster-based data aggregation mechanism, which helps minimize the communication cost. Clusterbased approach groups the sensor nodes in the sensor network. Each node of a group will send information to its Cluster Head, which then aggregates and forwards the information to the base station (Sink). We compare the performance of proposed Cluster-based Comb-Needle Model with the basic Comb-Needle Model using the parameters, namely, energy consumption and communication cost. The experimental results through Avrora Simulator on TinyOS Platform reveal that Clusterbased Comb-Needle Model for Data Aggregation helps a sensor network in conserving its energy, and thereby extending its life time.

A Mobile Ad hoc NETwork (MANET) is a self-organizing, temporary, infrastructure-free, multi-hop, dynamic topology wireless network that contains collection of cooperative autonomous freely roaming mobile nodes. The nodes communicate with each other by wireless radio links with no human intervention. Each mobile node functions as a specialized router to forward information to other mobile nodes. In order to provide efficient end-to-end communication with the network of nodes, a routing protocol is used to discover the optimal routes between the nodes. The routing protocols meant for wired networks can not be used for mobile ad hoc networks because of the mobility of nodes. Routing in ad hoc networks is nontrivial due to highly dynamic nature of the nodes. Various routing protocols have been proposed and widely evaluated for efficient routing of packets. This research paper presents an overview on classification of wide range of routing protocols for mobile ad hoc wireless networks proposed in the literature and shows the performance evaluation of the routing protocols: DSDV, AODV, FSR, LAR, OLSR, STAR and ZRP using the network simulator QualNet 4.0 to determine which protocols may perform best in large networks. To judge the merit of a routing protocol, one needs performance metrics (throughput, end-to-end delay, jitter, packet delivery ratio, routing overhead) with which to measure its suitability and performance. Our simulation experiments show that the LAR protocol achieve relatively good performance compared to other routing protocols

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