The sensor network is decentralized in nature due to which malicious nodes enter the network which are responsible to trigger various active and passive attacks. Due to the presence of malicious nodes in the network, the base station gets false information about the sensor nodes. Among the earlier proposed techniques distance based secure node localization technique efficient in terms of energy consumption. In this work, technique of cache node is used with the distance based technique for the secure node localization. The proposed improvement increase the network lifetime and also reduce the energy consumption. Keywords: LEACH, RFID, HARP, I. INTRODUCTIONWithin a wireless sensor network, there are numerous nodes spread across an area for monitoring the surroundings present. There is a sensor hub present within the network that comprises of sensors, actuators, memory, and a processor and facilitates communication amongst the nodes [1]. The wireless mode of communication is utilized for transmitting the data across the sensor nodes with the help of radio frequencies, infrared etc. and does not include any wired connections within it..Energy consumption can be diminished by building automation framework, all things considered by somewhere around 5% and 15% more for which are inadequately kept up and more seasoned structures [2]. To give great information resolution over the environment, better gadget integration and utilization of control systems, only an adequate number of sensors are required, beyond most wired building sensor networks can give.For sparing the energy of sensor nodes one of the clustering methodology is utilized. Through productive network organization every one of the nodes in sensor network can be partitioned into little groups is called clusters [3]. In every cluster has a cluster head and rest nodes are individual from that cluster. Clustering results in a two-level order in which cluster heads shape the higher level while part nodes frame the lower level. The clustering includes grouping nodes into clusters and choosing cluster heads periodically such that individuals from a cluster can speak with their cluster heads and these cluster heads send aggregated data received from its individuals to a base station [4]. The clustering procedure is utilized to minimize the energy consumption. By utilizing clustering, it reduces the packet collision and channel contention it increases the network throughput under high load. Clustering enhance the network lifetime of the sensor networks. Lifetime is the essential element to assessing the execution of the sensor networks [5]. The clustering approaches can't directly apply to wireless sensor networks, in light of the fact that these networks has one of a kind deployment and operational qualities. Wireless sensor networks are sent in ad hoc way they have a bigger number of nodes.Clustering algorithms for wireless sensor networks can be further separated into two principle classifications depending on cluster formation criteria and parameters ut...

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Wireless technologies have gradually become more and more involved into people's daily life. Among multicarrier transmission techniques, Orthogonal Frequency Division Multiplexing (OFDM) is the most popular one that uses parallel data streams. Compared with single carrier modulation, OFDM has many advantages as immunity to impulse interference, high spectral density, resilient to RF interference, robustness to channel fading, resistance to multipath, much lower computational complexity. In this paper, we will give an overview to OFDM technique, identify the PAPR problem and a technique for reducing PAPR (peak to average power ratio) in OFDM by changing the phase of some of the subcarriers.