Wireless sensor networks (WSN) usually consists of a large number of tiny sensors with limited computation capability, memory space and power resource. Many key pre-distribution techniques have been developed recently to establish pair wise keys between sensor nodes in WSN. Sensors are usually deployed for sensing data in the field. The communication of a wireless sensor network can be captured quite easily, thereby it requires security. To achieve security in wireless sensor network, key pre-distribution is essential. The key pre-distribution scheme makes use of symmetric matrices in order to establish a secret key between the sensor nodes. This scheme is known as Blom's scheme. It results in the establishment of a single key for communication between two sensor nodes. If it is captured by an adversary then the security is compromised, thus the resilience of the network is reduced. This scheme can be modified by making use of asymmetric matrices which generates two secret keys for two nodes. Thus two separate communication links are established between the nodes. If one of the communication links gets compromised by an adversary, there exists another link for secure communication between the nodes. Thus the resilience of the sensor network can be improved. Also in Blom's scheme Vandermonde matrix is used to generate private key but in this paper it is modified by using hankel matrix. The objective of this paper is to improve the resiliency of the network by generating the secret keys using asymmetric matrices.

In order to replace millimetre wave communication for extremely fast terabit wireless local and personal area network connectivity, researchers have been looking into the possibilities of the terahertz band for establishing wireless data communication at terabit rates. The IEEE 802.15 WPAN Terahertz Interest Group (IGTHz) has been created to encourage research in the terahertz bands and set standards for their use, in order to facilitate progress and advancement in this area. The specific objective of this study is to design and analyze a microstrip antenna working at 3.5 THz resonant frequency. The proposed novel antenna includes three layers: a top layer that represents the patch, a second layer that represents the substrate, and a bottom layer that represents the ground plane. It is designed using a 32 nm thin FR-4 substrate with a permittivity of 4.4. Using HFSS simulations, it was found that the proposed antenna has an overall efficiency greater than 85% within the working frequency range of 3.5 THz. Additionally, it exhibited an extremely low reflection coefficient (S11) of -43.61 dB at 3.5 THz, with an efficiency exceeding 80%. This simple and broadband antenna design could have relevance in high-speed data transmission networks.

A wireless sensor network consists of inexpensive power constrained sensors which collect data from the environment and transmit them towards the base station in a cooperative way. Reducing the energy and extending the wireless sensor networks lifetime, imposes a great confront. In this paper, the distributed Energy efficient clustering protocol was used to calculate the energy efficiency of the network. Existing DEEC was modified and developed a new protocol called MDEEC. MDEEC allows more number of data to be sent from the base station to the cluster head in a particular time interval. Compared to DEEC, MDEEC performs less delay for sending the data, thereby increasing the energy efficiency of the heterogeneous network.

This article describes about L / C / X triple band compact dipole array antenna for RADAR communication using FR-4 Substrate. The proposed antenna is designed over a range of 1.0–10.0 GHz. The objective of the paper is to achieve appreciable basic antenna parameters for ease adaptation in Monolithic Microwave Integrated Circuits (MMIC) Technology. It is able to preserve its high recital over RADAR Communication system operating at Triple band (L, C, X – band) microwave frequency range. The proposed structure resonates at L / C / X Microwave bands and thus the antenna becomes inevitability for numerous wireless applications. The antenna is fictitious on a substrate with height of 1.6 mm, length 48mm, width 60mm and a relative permittivity of 4.2. The proposed antenna yields a VSWR of about 1.74 (1.70 GHz), 1.66 (6.70 GHz), 1.26 (8.30 GHz) and gain of 2.56 dBi (1.70 GHZ), 1.78 dBi (6.70 GHz) and 3.94 dBi (8.30 GHz) under simulation. The antenna is designed and simulated using HFSS, which helps to obtain the antenna parameters such as VSWR, gain and Return loss.

Wireless sensor networks are a new class of distributed systems that are an integral part of the physical space they inhabit. Key distribution plays an important role in wireless sensor networks. In WSN, node capture attack is the most series attack. The aim of this paper is to improve the resistance against the node capture attack. So a double hash function key pre-distribution scheme is used to stop an adversary to get information of non-compromised sensor nodes from the compromised sensor nodes and the deployment model, is based on hexagonal to improve the local connectivity. The proposed scheme provides the best resilience against sensor nodes capture and the probability of links between any sensor nodes are compromised is zero after pair wise keys establishment.

The design of stacked patch antenna integrated with metamaterial for broadband applications to achieve appreciable gain, directivity and low return loss is presented in this article. It mainly focuses on optimization and easy adaptation in MMIC technology. The antenna is designed to carry out by combining two Microstrip patch antenna in a stack manner and Metamaterial is implemented by Complementary Split Ring Resonator (CSRR) technique on both side of the patch antenna and slots are introduced at four corners of the patch and adjacent to the metamaterial. The designed antenna is capable of maintaining its performance over wireless system at C band (4-8 GHz) frequency range. The substrate used is FR-4 with thickness of 0.8mm and permittivity) is 4.2. It is simulated using Advanced Design System (ADS) and it is resonated around 6 GHz. It yields a VSWR of about 1.014 (6.25 GHz), 1.022 (5.829 GHz) and 1.015 (6.522 GHz) under simulation and 1.25 (6.03 GHz), 1.119 (5.74 GHz) and 1.247 (5.36 GHz) in measurements respectively. Thus the antenna becomes a necessity for many applications in recent wireless communications such as RADAR and space applications.