Wireless Sensor Networks (WSN) has gained interest in many applications and it becomes important to improve its performance. Antennas and communication performance are most important issues of WSN. In this paper, an adaptive concentric circular array (CCA) is proposed to improve the link between the sink and sensor nodes. This technique is applied to the new High – Altitude Platform (HAP) Wireless Sensor Network (WSN). The proposed array technique is applied for two coverage scenarios; a wider coverage cell of 30 km radius and a smaller cell of 8 km radius. The feasibility of the link is discussed where it shows the possibility of communications between the HAP sink station and sensor nodes located on the ground. The proposed CCA array is optimized using a modified Dolph-Chebyshev feeding function. A comparison with conventional antenna models in literature shows that the link performance in terms of bit energy to noise power spectral density ratio can be improved by up to 11.37 dB for cells of 8 km radius and 16.8 dB in the case of 30 km radius cells that make the link at 2.4 GHz feasible and realizable compared to using conventional antenna techniques.

The rise of the Internet accelerates the creation of various large-scale online social networks. The online social networks have brought considerable attention as an important medium for the information diffusion model, which can be described the relationships and activities among human beings. The online social networks’ relationships in the real world are too big to present with useful information to identify the criminal or cyber attacks. The methodology for information security analysis was proposed with the complementary of Cluster Algorithm and Social Network Analysis, which presented anomaly and cyber attack patterns in online social networks and visualized the influencing nodes of such anomaly and cyber attacks. The closet vertices of influencing nodes could not avoid from the harmfulness in social networking. The new proposed information security analysis methodology and results were significance analysis and could be applied as a guide for further investigate of social network behavior to improve the security model and notify the risk, computer viruses or cyber attacks for online social networks in advance.

The purpose of paper is to compute reliability of Digital Tele-Protection System employing Digital Microwave Radio Link. In this paper, the whole Tele-Protection system is divided into six subsystems. The first subsystem is digital relaying equipment. Second subsystem is the tale-protection signaling equipment where the timing to sample line power currents is synchronized. Both relaying and Tele-Protection signaling equipments, are now assemble three-phase current data, sampled at 600 Hz for 50 Hz EHV systems and some control data into a 90 bit frame format at a transmission rate of 54 Kb/s. A frame consists of a frame synchronization field and some information fields including a cycle’s redundancy check field. The third subsystem, Tele-Protection signed multiplexing equipment generates a super frame by multiplexing the seven, 54 Kb/s Tele-Protection signals into a 1.544 Mb/s stage using multi-point sampling technique to minimize the delay time variation and send them to the subsystem four, which is radio equipment, from here the data is transmitted with the help of the channel (subsystem 5) to the repeater station (subsystem 6). The subsystem six is used to remove the noise and to improve the power of the data. In this paper, we have taken standby digital relaying equipment and that can be online through an imperfect switching device. Also parallel redundant Tele-Protection signaling equipment is taken to improve system’s overall performance.

Rapid technological advances and innovations in the area of autonomous systems push the researchers towards autonomous networked systems with emphasis on Wireless Multimedia Sensor Networks (WMSNs). In WMSN event-driven applications, it is critical to report the detected events in the area, resulting in sudden bursts of traffic due to occurrence of spatially-correlated or multiple events, causing loss of data. Also, nodes have very limited power due to hardware constraints. Packet losses and retransmissions resulting from congestion, cost precious energy and shorten the lifetime of sensor nodes. Till now, in WMSNs, Congestion control techniques are based on detection of congestion and recovery, but they cannot eliminate or prevent the occurrence of congestion. Collision is a symptom of congestion in the wireless channel and can result in a time-variant channel capacity. The method in the proposed algorithm is that the routing algorithms do not precalculate the routes and the next step is chosen dynamically. Decisions are made based on the congestion degree on neighbor nodes; each node sees its own queue backlog and neighbor's queue backlog and chooses its own degree and route based on the queue backlogs obtained from its neighbors. If there is two or more data with the same condition in the backpressure routing, we use service differentiation to prioritize packets. The results obtained from simulation test done by NS-2 simulator indicate that the proposed model is more innovative and presents better performance in compare with CCF and PCCP protocols.

Optical Burst Switching (OBS) is the future of optical internet which provides a promising architecture to efficiently utilize WDM and to fulfill today’s Internet traffic demands. Since this area is yet to mature there is a darn need to study its various protocols. Network simulator is an important tool for researchers and academicians to simulate and model the actual network at a reduced cost compared to the real test-bed experimentation. In this paper various OBS simulators are comparatively surveyed, while highlighting their merits and demerits.

Advancement in software, hardware and communication technologies have led to the development of design and implementation of different types of networks that are deployed in various environments. One such network that has gained a lot of interest in the last few decades is the Vehicular Ad-Hoc Network (VANET). VANET has become an active area of research, development and standardization because it has remarkable potential to improve vehicle and road safety, traffic management, and also provide comfort to both drivers and passengers. Roadside units (RSUs) are a vital component of Vehicular ad hoc network (VANET). Mainly, the density and location of RSUs decides the success of a VANET. But, the sky-high deployment costs of the RSUs make it impossible to deploy a large number of RSUs on the specific area or road. Thus, there rises a need to optimally deploy a restricted number of RSUs in a given region in order to achieve maximum performance. This paper presents a new TDB based RSUs deployment algorithm with a goal of attaining high efficiency and cover maximum area. Matlab platform is used to assess the performance of the proposed algorithm using several performance metrics.

Audio communications in IP based networks have been revolutionized by the introduction of VoIP applications. High cost-efficiency has made VoIP to be the communication means in today’s world; and this trend is anticipated to be continued on an ongoing basis. The performance of VoIP significantly depends on the efficiency of the audio codecs used in any communication scenario which make the study on the performance issues of audio codecs in VoIP applications worth investigating. IPv6 is the new version of IP, which will gradually replace the current IPv4 as the transition from IPv4 to IPv6 is already in place. This demands the scrutiny of the audio codecs being used in IPv4 to be tested for their compatibility in IPv6 in terms of desired performance. This paper presents the study on the performance of selected audio codecs that are widely used in VoIPv4. G.711, G.729A and G.723.1 codecs were chosen for the study in VoIPv6 based scenarios presented in this paper. The selected audio codecs were applied in IPv6 based voice communication network scenarios to determine their performance efficiency by observing various QoS parameters. The study was done by means of simulation using OPNET.

All the proposed Hill cipher modifications have been restricted to the use of dynamic keys only. In this paper, we propose an extension of Hill cipher modification based on eigenvalues HCM-EE, called HCM-EXDKS. The proposed extension generating dynamic encryption key matrix by exponentiation that is made efficiently with the help of eigenvalues, HCM-EXDKS introduces a new class of dynamic keys together with dynamically changing key size. Security of HCM-EXDKS is provided by the use of a large number of dynamic keys with variable size. The proposed extension is more effective in the encryption quality of RGB images than HCM-EE and Hill cipher-known modifications in the case of images with large single colour areas and slightly more effective otherwise. HCM-EXDKS almost has the same encryption time as HCM-EE, and HCM-HMAC. HCM-EXDKS is two times faster than HCM-H, having the best encryption quality among Hill cipher modifications compared versus HCM-EXDKS.