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In a communication system, security and reliability have an important impact on the quality of services. In this paper, we investigate power and subcarrier allocation of a transmitter over the downlink of an OFDMA system with security considerations among users in the presence of a jammer. This paper considers the interaction between the jammer and the transmitter as a zero-sum game where the objective function is the transmitter's secrecy sum-rate. In order to allocate available resources, we solve the optimization problem of each player to characterize their optimal strategies. Considering the intractability of the closed form Nash equilibrium for general power regime, we show the existence of pure Nash equilibrium point for low total power regimes of the transmitter and the jammer and attain an expression for each regime. Finally, we examine the jamming power effect on the secrecy sum-rate and acquire lower and upper bounds of this rate using simulations.

This paper mainly discusses about the maximum light absorption by nano-grating structure assisted metal-semiconductor-metal-photodetectors (MSM-PDs). The nano-grating structure assisted MSM-PDs are suitable candidate for various applications, such as faster optical fibre communications, high-speed chip-to-chip interconnects, sensor networks and high-speed sampling. For this modelling, finite difference time domain (FDTD) simulation tool is used to simulate and calculate the light absorption enhancement factor (LAEF) of nano-structured MSM-PDs. In this research, various nano-grating shapes are used, such as, hyperbolic, trapezoidal, triangular and rectangular. Based on simulation results, we have compared the LAEF of nano-grating shape dependent MSM-PDs. In a particular case of simulation, rectangular shaped nano-grating structure MSM-PDs achieved about 12-times higher LAEF than the conventional MSM-PDs.

Metaheuristics are high level strategies for exploring the search space by using different methods to solve global optimization problems. In this paper, Football Game Algorithm has been proposed as a new metaheuristic algorithm based on the simulation of football players' behavior during a game for finding best positions to score a goal under supervision of the team coach. Simulation of humans' intelligences who are working together as a team to reach a specific goal instead of simulating the intelligence of various animal swarms in the nature is the most important distinction of the proposed algorithm to other existing algorithms that also introduces a new approach for making balance between diversification and intensification. Football Game Algorithm is a nature inspired, population base algorithm with ability in finding multiple global optimums. We have studied general football game tactics and idealized its characteristics to formulate Football Game Algorithm. We have then compared the proposed algorithm with other metaheuristics, including standard and modified particle swarm optimization and bat algorithm. The result of comparison studies show that the proposed Algorithm outperforms other algorithms and also has more robust performance. Finally, we have discussed and concluded by pointing out special attributes of the Football Game Algorithm.

A novel plasmonics-based metal-semiconductor-metal photodetector is introduced which dramatically modifies the light transmission spectra when the sub-wavelength central slit is not bare. FDTD method has been utilized to simulate the behavior of the device with significant responsivity.

In this paper we consider the attitude synchronization task for rigid body networks. The configurations of such systems evolve on SO(3), which is a nonlinear manifold and needs a special treatment for fulfilling this task. We propose two robust adaptive algorithms to handle the effects of unmodeled dynamics and unknown inertia matrices of agents. Our first approach is based on σ-modification method which “trap” the trajectories of the system in to a small neighborhood around the origin. In the second algorithm, the effects of external disturbances are removed using a discontinuous function. We use Lyapunov methods to prove the main results of this paper. Simulation results show the effectiveness of our proposed methods.

Nano-structured metal-semiconductor-metal photodetectors (MSM-PDs) are enable to assist in future high-speed communication devices achieving high responsivity-bandwidth characteristics. Finite difference time-domain (FDTD) method is used to calculate the light absorption enhancement of nano-grating assisted MSM-PDs near the design wavelength by varying detector's geometrical parameters in comparison with a conventional device. The substrate containing apertures and the nano-gratings are optimized in thickness to trigger extraordinary optical transmission. Besides, it demonstrates how the coupling condition satisfies the oscillating charge densities evolution to the surface plasmon polaritons under illumination of polarized light. The simulation results confirm that the light absorption enhancement of nano-grating assisted MSM-PDs is ∼13.5-times better than the conventional MSM-PDs.

We use finite difference time-domain (FDTD) method to calculate the light absorption enhancement of nano-grating assisted metal-semiconductor-metal photo-detectors (MSM-PDs). The simulated results show that the light absorption enhancement of nano-grating assisted MSM-PD is ∼9-times better than conventional MSM-PD.

Finite difference time-domain (FDTD) method is used to calculate the light absorption enhancement of nano-grating assisted metal-semiconductor-metal photo-detectors (MSM-PDs). Simulated results show that the light absorption of plasmonics-based MSM-PDs is ∼12-times better than conventional MSM-PDs.