R. Badlishah Ahmad

Electronically reconfigurable beam steering antenna using embedded RF PIN based parasitic arrays (ERPPA)

In this paper, an electronically reconflgurable beam steering antenna using embedded RF PIN switches based parasitic array (ERPPA) is proposed for modern wireless communication systems that operate at 5.8GHz frequency. In the proposed antenna, a single driven element is fed by a coaxial probe, while each of the two parasitic elements is integrated with an RF PIN switches that embedded inside the substrate. In the conventional reconflgurable antennas, the RF PIN switches are mounted on narrow slots created on the top or bottom layer of the radiator/parasitic elements, which could lead to the dimensional changes of the antenna and degrade the performance in terms of beam steering and return loss. However, this research proposes an exclusive solution where the RF PIN diodes at parasitic elements are embedded inside the substrate thus no additional slots have to be created to mount the SMCs on the antenna. In this regard, the proposed antenna is highly competent to eliminate the intermodulation efiect generated by the RF PIN diodes and the other passive elements associated with the PIN diodes. In this research, extensive investigations revealed that the parasitic element dimension and the selection of RF PIN switches signiflcantly in∞uence

Characteristic region based image steganography using Speeded-Up Robust Features technique

Steganography is the art and science of invisible communication. It is employed in different useful applications, like, safe circulation of secret data and Medical Imaging Systems. For most of the current steganography techniques, information hiding modifies almost all the cover components, which may negatively affect the visual quality of the image and increase the possibility of losing data after the possible attacks. This paper presents a new region based steganography technique, which hides data in the robust regions of the image. First, the Speeded-Up Robust Features (SURF) is used to find the most robust regions in the image. Then, the data embedding is achieved in a content-based manner by modifying the wavelet transform coefficients of those robust regions. Experimental results show the proposed algorithm allows hiding data invisibly with an accurate retrieval in the presence of lossy compression or noise. Moreover, the visual quality of the embedded image is high.

Mitigation of multiple access interference using two-dimensional modified double weight codes for optical code division multiple access systems

We proposed newly two-dimensional (2- D ) spectral amplitude coding optical code division multiple access (OCDMA) scheme using modified double weight (MDW) code capable of suppressing phase-induced intensity noise (PIIN). The architecture of the spectral/spatial MDW OCDMA system with the property of multi-access interference cancellation is presented. The proposed code exhibits good cross-correlation property. At the optimized data transmission rate of 0.745 Gbps, 2-D MDW, M = 63, N = 3, reaches maximum cardinality of 200% increases compared to 2- D perfect difference code, M = 57, N = 3. The performance is severely deteriorated if the data rate further increases above 0.745 Gbps. The proposed code meets the optical transmission requirements at 10−9 bit error rate error floor, with lowest effective transmitted power ( P sr), −17.5  dBm, in comparison to the others through minimizing interference noise that result in PIIN suppression. The proposed system reaches optimum requirements performance in terms of cardinality, data transmission rate, and low effective transmitted power.

Longitudinal, Lateral and Transverse Axes of Forearm Muscles Influence the Crosstalk in the Mechanomyographic Signals during Isometric Wrist Postures

Problem Statement In mechanomyography (MMG), crosstalk refers to the contamination of the signal from the muscle of interest by the signal from another muscle or muscle group that is in close proximity. Purpose The aim of the present study was two-fold: i) to quantify the level of crosstalk in the mechanomyographic (MMG) signals from the longitudinal (Lo), lateral (La) and transverse (Tr) axes of the extensor digitorum (ED), extensor carpi ulnaris (ECU) and flexor carpi ulnaris (FCU) muscles during isometric wrist flexion (WF) and extension (WE), radial (RD) and ulnar (UD) deviations; and ii) to analyze whether the three-directional MMG signals influence the level of crosstalk between the muscle groups during these wrist postures. Methods Twenty, healthy right-handed men (mean ± SD: age = 26.7±3.83 y; height = 174.47±6.3 cm; mass = 72.79±14.36 kg) participated in this study. During each wrist posture, the MMG signals propagated through the axes of the muscles were detected using three separate tri-axial accelerometers. The x-axis, y-axis, and z-axis of the sensor were placed in the Lo, La, and Tr directions with respect to muscle fibers. The peak cross-correlations were used to quantify the proportion of crosstalk between the different muscle groups. Results The average level of crosstalk in the MMG signals generated by the muscle groups ranged from: 34.28–69.69% for the Lo axis, 27.32–52.55% for the La axis and 11.38–25.55% for the Tr axis for all participants and their wrist postures. The Tr axes between the muscle groups showed significantly smaller crosstalk values for all wrist postures [F (2, 38) = 14–63, p<0.05, η 2 = 0.416–0.769]. Significance The results may be applied in the field of human movement research, especially for the examination of muscle mechanics during various types of the wrist postures.

Extending wireless sensor network lifetime with base station repositioning

In wireless sensor networks, the major source of a sensor node failure is battery exhaustion and replacing this energy source in the field is usually not practical. Therefore, the use of energy efficient infrastructure, such as repositioning the base station in a clustered wireless sensor network, is able to prolong the lifetime of the network and improve the overall network data. In this paper, we proposed an energy-efficient protocol for the repositioning of mobile base station using particle swarm optimization (PSO) in wireless sensor networks. Simulation results demonstrate that the proposed protocol can improve the network lifetime, data delivery and energy consumption compared to existing energy-efficient protocols developed for this network.

Coverage Extension and Balancing the Transmitted Power of the Moving Relay Node at LTE-A Cellular Network

The poor capacity at cell boundaries is not enough to meet the growing demand and stringent design which required high capacity and throughput irrespective of users location in the cellular network. In this paper, we propose new schemes for an optimum fixed relay node (RN) placement in LTE-A cellular network to enhance throughput and coverage extension at cell edge region. The proposed approach mitigates interferences between all nodes and ensures optimum utilization with the optimization of transmitted power. Moreover, we proposed a new algorithm to balance the transmitted power of moving relay node (MR) over cell size and providing required SNR and throughput at the users inside vehicle along with reducing the transmitted power consumption by MR. The numerical analysis along with the simulation results indicates that an improvement in capacity for users is 40% increment at downlink transmission from cell capacity. Furthermore, the results revealed that there is saving nearly 75% from transmitted power in MR after using proposed balancing algorithm. ATDI simulator was used to verify the numerical results, which deals with real digital cartographic and standard formats for terrain.

Cross-talk in mechanomyographic signals from the forearm muscles during sub-maximal to maximal isometric grip force.

Purpose This study aimed: i) to examine the relationship between the magnitude of cross-talk in mechanomyographic (MMG) signals generated by the extensor digitorum (ED), extensor carpi ulnaris (ECU), and flexor carpi ulnaris (FCU) muscles with the sub-maximal to maximal isometric grip force, and with the anthropometric parameters of the forearm, and ii) to quantify the distribution of the cross-talk in the MMG signal to determine if it appears due to the signal component of intramuscular pressure waves produced by the muscle fibers geometrical changes or due to the limb tremor. Methods Twenty, right-handed healthy men (mean ± SD: age  = 26.7±3.83 y; height  = 174.47±6.3 cm; mass  = 72.79±14.36 kg) performed isometric muscle actions in 20% increment from 20% to 100% of the maximum voluntary isometric contraction (MVIC). During each muscle action, MMG signals generated by each muscle were detected using three separate accelerometers. The peak cross-correlations were used to quantify the cross-talk between two muscles. Results The magnitude of cross-talk in the MMG signals among the muscle groups ranged from, R2x, y = 2.45–62.28%. Linear regression analysis showed that the magnitude of cross-talk increased linearly (r2 = 0.857–0.90) with the levels of grip force for all the muscle groups. The amount of cross-talk showed weak positive and negative correlations (r2 = 0.016–0.216) with the circumference and length of the forearm respectively, between the muscles at 100% MVIC. The cross-talk values significantly differed among the MMG signals due to: limb tremor (MMGTF), slow firing motor unit fibers (MMGSF) and fast firing motor unit fibers (MMGFF) between the muscles at 100% MVIC (p<0.05, η 2 = 0.47–0.80). Significance The results of this study may be used to improve our understanding of the mechanics of the forearm muscles during different levels of the grip force.

Energy consumption optimization with Ichi Taguchi method for Wireless Sensor Networks

Wireless Sensor Networks (WSN) consists of sensor nodes for monitoring and reporting sensible changes on a field to a specific server. One of the applications of WSN is large area monitoring, where sensor nodes are placed in far fields with limited power sources. Due to the adhered reason, the energy consumption of sensor nodes is considered as one of the major challenge in WSN. Many factor in WSN contributes to energy consumption such as Medium Access Control protocol (MAC), the network topology, and routing protocol. With the variety of factors that affects the energy consumption in WSN; the challenge of optimizing WSN networks toward a low energy consumption is becoming a hard problem. In the literature many efforts are paid for designing, implementing, and improving protocols in terms of power consumption. However, few efforts are paid for optimizing the existing protocols and other network parameters toward a green technology. This paper focuses in WSN infrastructure and protocols optimization by introducing the Ichi Taguchi (Taguchi) optimization method. Taguchi method is used to predict the best design parameters to achieve optimal performance parameters. Moreover, Taguchi method is used to optimize the energy consumed by sensor nodes against network protocols and network topology design parameters. A simulation experiments are curried out on the discrete event simulator OMNET++ for the purposes of this research paper. The obtained results show the impact of the network protocols toward the energy consumption. Furthermore, a proposed network topology and protocols set is introduced, and compared against the existing once.

Prolonging lifetime of wireless sensor networks with mobile base station using particle swarm optimization

Wireless sensor networks are a family of networks in wireless communication system and have the potential to become significant subsystem of engineering applications. In view of the fact that the sensor nodes in wireless sensor networks are typically irreplaceable, this type of network should operate with minimum possible energy in order to improve overall energy efficiency. Therefore, the protocols and algorithms developed for sensor networks must incorporate energy consumption as the highest priority optimization goal. Since the base station in sensor networks is usually a node with high processing power, high storage capacity and the battery used can be rechargeable, the base station can be utilized to collect data from each sensor node in the sensing area by moving closer to the transmitting node. In this paper, we proposed an energy-efficient protocol for the movement of mobile base station using particle swarm optimization (PSO) method in wireless sensor networks. Simulation results demonstrate that the proposed protocol can improve the network lifetime, data delivery and energy consumption compared to existing energy-efficient protocols developed for this network.

A Ground-Plane-Truncated, Broadly Steerable Yagi–Uda Patch Array Antenna

A low-profile, broadly steerable, and reconfigurable array antenna with parasitic patches is proposed and investigated in this work. For patch-type antenna arrays, improvement of the beam-scanning range using parasitic patches is very limited. The typically achieved scanning range is between -30° and +30° from the broadside. Increasing the number of parasitic elements generally will only provide a mere 3 °-5 ° improvement in terms of the beam-scanning range. In this work, the scanning range is improved by approximately 57% via a novel approach combining the additional parasitic elements and ground plane reduction techniques. Numerical and experimental results have validated that the array is capable of producing five different beam patterns directed towards -50°, -30°, 0°, +30°, and +50° steerable at the xz-plane using an optimized switching method and careful switch location selection on the parasitic elements.