Mitigating Performance Degradation in Congested Sensor Networks

Data generated in wireless sensor networks may not all be alike: some data may be more important than others and hence may have different delivery requirements. In this paper, we address differentiated data delivery in the presence of congestion in wireless sensor networks. We propose a class of algorithms that enforce differentiated routing based on the congested areas of a network and data priority. The basic protocol, called congestion-aware routing (CAR), discovers the congested zone of the network that exists between high-priority data sources and the data sink and, using simple forwarding rules, dedicates this portion of the network to forwarding primarily high-priority traffic. Since CAR requires some overhead for establishing the high-priority routing zone, it is unsuitable for highly mobile data sources. To accommodate these, we define MAC-enhanced CAR (MCAR), which includes MAC-layer enhancements and a protocol for forming high-priority paths on the fly for each burst of data. MCAR effectively handles the mobility of high-priority data sources, at the expense of degrading the performance of low-priority traffic. We present extensive simulation results for CAR and MCAR, and an implementation of MCAR on a 48-node testbed.     

Comprehensive review for energy efficient hierarchical routing protocols on wireless sensor networks

Wireless Networks - In recent years, wireless sensor networks (WSNs) have played a major role in applications such as tracking and monitoring in remote environments. Designing energy efficient...     

Two-dimensional analytical modeling of fully depleted DMG SOI MOSFET and evidence for diminished SCEs

A two-dimensional (2-D) analytical model for the surface potential variation along the channel in fully depleted dual-material gate silicon-on-insulator MOSFETs is developed to investigate the short-channel effects (SCEs). Our model includes the effects of the source/drain and body doping concentrations, the lengths of the gate metals and their work functions, applied drain and substrate biases, the thickness of the gate and buried oxide and also the silicon thin film. We demonstrate that the surface potential in the channel region exhibits a step function that ensures the screening of the drain potential variation by the gate near the drain resulting in suppressed SCEs like the hot-carrier effect and drain-induced barrier-lowering (DIBL). The model is extended to find an expression for the threshold voltage in the submicrometer regime, which predicts a desirable "rollup" in the threshold voltage with decreasing channel lengths. The accuracy of the results obtained using our analytical model is verified using 2-D numerical simulations.     

A Hybrid Fractal Metamaterial Inspired Multiband Antenna for Wireless Applications

Wireless Personal Communications - In this paper a multiband (hepta-band) antenna loaded with hybrid fractal structures and metamaterial cell (SRR/CSRR) is proposed to cover the wireless...     

Analytical modeling for 3D potential distribution of rectangular gate (RecG) gate-all-around (GAA) MOSFET in subthreshold and strong inversion regions

In this paper, we have introduced an analytical subthreshold and strong inversion 3D potential model for rectangular gate (RecG) gate-all-around (GAA) MOSFET. The subthreshold and strong inversion potential distribution in channel region of a RecG MOSFET is obtained respectively by solving 3D Laplace and 3D Poisson equations. The assumed parabolic potential distribution along the z-axis in channel direction is appropriately matched with 3D device simulator after consideration of z-depended characteristic length in subthreshold region. For accurate estimation of short channel effects (SCE), the electrostatics near source and drain is corrected. The precise gate-to-gate potential distribution is obtained after consideration of higher order term in assumed parabolic potential profile. The model compares well with numerical data obtained from the 3D ATLAS as a device simulator and deckbuild as an interactive runtime of Silvaco Inc.     

Implication of molecular orientation on charge transport and gas sensing characteristics of cobalt–phthalocyanine thin films

Charge transport and gas sensing characteristics of cobalt phthalocyanine films deposited along (ATB) and perpendicular (PTB) to the natural twin boundaries of (0 0 1) LaAlO₃ substrate have been investigated. The charge carrier mobility of ATB films (∼5 cm² V⁻¹ s⁻¹) is five orders of magnitude higher compared to that of PTB films (∼7 × 10⁻⁵ cm² V⁻¹ s⁻¹), suggesting that twin boundaries acts like a template for ordering of molecules. The ATB films on exposure to ammonia showed a reversible increase of resistance, with fast response and recovery. In contrast PTB films showed same sensitivity, but exhibits base resistance drift along with sluggish response.     

Optical orthogonal codes-new bounds and an optimal construction

A technique for constructing optimal OOCs (optical orthogonal codes) is presented. It provides the only known family of optimal (with respect to family size) OOCs having λ=2. The parameters (n ,ω,λ) are respectively (p^2m-1, p^m+1,2), where p is any prime and the family size is p^m-2. Three distinct upper bounds on the size of an OOC are presented that, for many values of the parameter set (n,ω,λ), improve upon the tightest previously known bound     

A study of protean systems—Redundancy optimization in consecutive-k-out-of-n:F systems

A Protean system is a system that is subject to changes from time to time. A consecutive-k-out-of-n:F system that has a fluctuation of demand on the system performance, may be classed under Protean systems. The changing demand may be handled by improving the system performance using some extra resources. In this paper, the extra resources considered are in the form of i.i.d. components. These components are allocated with the objective of maximising the system reliability. There are three methods developed in this paper. The first method is developed by formulating the problem mathematically. The second method involves enumeration of all possible allocations of a given number of i.i.d. components. The third method is a heuristic, based on component reliability importance. The accuracy of the heuristic is established by comparing it with the second method. These two methods are compared using computer programs developed by one of the authors.     

Steganalysis of Network Packet Length Based Data Hiding

Recently, data hiding by modifying network parameters like packet header, payload, and packet length has become popular among researchers. Different algorithms have been proposed during the last few years which have altered the network packets in different ways to embed the data bits. Some of these algorithms modify the network packet length for embedding. Although most of the packet length based embedding schemes try to imitate the normal network traffic distribution, they have altered the statistical distribution of network packet lengths during embedding. These statistical anomalies can be exploited to detect such schemes. In this paper, a second order detection scheme for packet length based steganography has been proposed. A comprehensive set of experiments have been carried out to show that the proposed detection scheme can detect network packet length based steganography with a considerably high accuracy.     

Coordinated control of TCSC and UPFC to aid damping oscillations in the power system

A valid damping of oscillations is an upcoming extensive challenge while maintaining the stability of the power system. This oscillation generally occurs due to the fluctuation raised, when two systems are interconnected. This paper addresses the oscillation occurred in the power system as the main challenge, which thus performs an effective simulation in 68-bus system. Here, it promotes a sufficient CC with two FACTS devices such as TCSC and UPFC, which are connected with PSS. Further, it adopts firefly algorithm to enable the CC among the FACTS devices. To the next of the simulation, this paper compares the performance of the FF- CC with conventional optimisations include GSO, PSO, GA and ABC algorithms to enable CC. Further, it provides a detailed analysis of the impact of PSS and loading effects on CC. As a result, the performance of FF-CC hands over the stable power system with powerful damping of oscillations, after comparing it with the existing methods.

Abbreviations: ABC, Artificial Bee Colony; ICA, Imperialist Competitive Algorithm; AVR, Automatic Voltage Regulators; NETS, New England test system; BFOA, Bacteria Foraging Optimization Algorithm; NYPS, New York power system; BSO, Bacterial Swarm Optimization; PSO, Particle Swarm Optimization; CC, Coordinated Control; PSS, Power System Stabilizers; COA, Chaotic Optimization Algorithm; STATCOM, Static Synchronous Compensator; CS, Cuckoo Search; SSSC, Static Synchronous Series Compensator; FACTS, Flexible Alternating Current Transmission System; SVC, Static Var Compensator; GA, Genetic Algorithm; TCSC, Thyristor Controlled Series Capacitor; GSO, Gravitational Search Algorithm; UPFC, Unified Power Flow Controller