Iti Saha Misra

Improved Adaptive Bacteria Foraging Algorithm in Optimization of Antenna Array for Faster Convergence

This paper proposes an improved adaptive approach involving Bacterial Foraging Algorithm (BFA) to optimize both the amplitude and phase of the weights of a linear array of antennas for maximum array factor at any desired direction and nulls in specific directions. The Bacteria Foraging Algorithm is made adaptive using principle of adaptive delta modulation. To show the improvement in making the algorithm adaptive, results for both adaptive and nonadaptive algorithms are given. It is found that Adaptive Bacteria Foraging Algorithm (ABFA) is capable of improving the speed of convergence as well as the precision in the desired result.

Bandwidth and Delay Guaranteed Call Admission Control Scheme for QOS Provisioning in IEEE 802.16e Mobile WiMAX

An efficient Call Admission Control (CAC) scheme for IEEE 802.16e Mobile WiMAX that satisfies both bandwidth and delay guarantee to the admitted connections has been proposed in this paper. The proposed CAC scheme provides higher priority to Handoff connections, because it is more annoying to drop an ongoing connection than blocking a newly originated connection. Also UGS connections are given higher priority because UGS is the most common service used by the people for communication in everyday life. An analytical model is developed to evaluate the performance of the CAC scheme. The proposed CAC scheme is compared with two other existing CAC schemes proposed in literatures. Numerical results show that the proposed CAC scheme could be the better choice forAn efficient Call Admission Control (CAC) scheme for IEEE 802.16e Mobile WiMAX that satisfies both bandwidth and delay guarantAn efficient call admission control (CAC) scheme for IEEE 802.16e Mobile WiMAX that satisfies both bandwidth and delay guarantee to the admitted connections has been proposed in this paper. The proposed CAC scheme provides higher priority to handoff connections, because it is more annoying to drop an ongoing connection than blocking a newly originated connection. Also UGS connections are given higher priority because UGS is the most common service used by the people for communication in everyday life. An analytical model is developed to evaluate the performance of the CAC scheme. The proposed CAC scheme is compared with two other existing CAC schemes proposed in literatures. Numerical results show that the proposed CAC scheme could be the better choice for admission control in terms of blocking and dropping probabilities of the connections and bandwidth utilization of the system.

DESIGN, ANALYSIS AND OPTIMIZATION OF V-DIPOLE AND ITS THREE-ELEMENT YAGI-UDA ARRAY

This paper presents an optimum design technique ofan asymmetric V-dipole antenna and its a three-element Yagi-Uda array using Genetic Algorithm (GA). The optimization parameter for the V-dipole is the directivity and that for the Yagi-Uda array are the input impedance and directivity. The theoretical analysis has been done using a Moment-Method technique in a very simple step-by-step way, and subsequently the GA is applied for obtaining the optimized parameters. Comparative results are provided for 3-elements straight dipole Yagi and V-dipole Yagi array. Further, analysis for directivity with respect to included angle is given for the GA based optimization problem that gives an important aspect in the design ofV-Yagi.

Performance study of mobile WiMAX network with changing scenarios under different modulation and coding

WiMAX—the Worldwide Interoperability for Microwave Access is a promising technology for offering high-speed data, video and multimedia services over mobile platform evolving toward all IP networks. The increasing demand of WiMAX for VoIP and high-speed multimedia is due to the simplicity of installation and cost reduction compared with the traditional wired DSL cable. The challenges to service providers lie with the Quality of Service (QoS) under varying fading environment while at the same time maximizing for resource utilization. In this paper, a rigorous and comprehensive performance study of mobile WiMAX has been made with respect to adaptive modulation and coding techniques considering the variation in the speed of the mobile, path-loss, scheduling services and application type for comparing with the fixed type of modulations. The OPNET 14.5.A modeler for WiMAX platform has been used as simulator for adaptation at the physical layer of the transmission in WiMAX OFDMA structure. Observation reveals that dynamic adaptation of modulation and coding schemes based on channel condition enables better QoS while consuming low overall bandwidth of the system. Copyright

An Approach for Optimal Hierarchical Mobility, Management Network Architecture

The focus of this paper is to get the optimal hierarchical mobility management solution for next generation wireless IP-based networks. Hierarchical architectures prove advantageous in minimizing signaling overhead by limiting registration signaling locally. Our ultimate goal is to find the optimum hierarchy level, which should provide best performance in terms of networks parameters like signaling overhead, handoff latency and frequency of location updates. For this purpose an n-tiered architecture has been considered and optimality test on the number of tiers has been performed through analytical and ns-2 based simulation results. From the performance evaluation it is seen that time-bandwidth product is minimum for three-tiered network architecture leading as the optimal solution

Study of impedance and radiation properties of a concentric microstrip triangular-ring antenna and its modeling techniques using FDTD method

A concentric microstrip triangular-ring antenna structure using the log-periodic principle for increasing the impedance bandwidth of the microstrip patch antenna is described. The finite-difference time-domain (FDTD) method is applied to analyze the proposed structure. A special technique to model the slanted metallic boundaries of the triangular ring has been used in the general FDTD algorithm to avoid the staircase approximation. The method improves the accuracy of the original FDTD algorithm without increasing the complexity. The radiation patterns at different frequencies over a wide bandwidth are obtained experimentally.

A Comparative Study of Optimization Techniques in Adaptive Antenna Array Processing: The Bacteria-Foraging Algorithm and Particle-Swarm Optimization

This paper presents a comparative study between the Bacteria-Foraging (BF) and Particle-Swarm Optimization (PSO) algorithms, and their application to the antenna-array optimization problem. The performance of the Bacteria-Foraging Algorithm is studied by varying its different parameters in beamforming and null-steering problems. Null steering along with sidelobe suppression is also done for various degrees of complexity. A generic cost function is developed, the parameters of which can be controlled to meet the requirements of the particular application. The two algorithms are compared for null depth, average sidelobe level, and rate of convergence for different numbers of interference signals. The performance of these methods are compared for output noise power for the same noise inputs. Results are shown for a linear dipole antenna-array system.

Study of enhanced VoIP performance under congested wireless network scenarios

Stringent QoS maintenance in a wireless environment for VoIP communication is a major challenge. VoIP inherently generates constant bit rate traffic and is highly sensitive to network delay. However, unpredictable network congestion makes a VoIP session so degraded that its QoS goes below a tolerable limit. Accordingly, a suitable solution is needed to adapt varying network conditions satisfying minimum QoS while maintaining transparency to the end user. We have extensively studied the effect of variable voice packet payload size with changing number of voice sample frames in the payload of the RTP packets. For this, we have used OPNET Modeler 14.5.A to observe the performance in terms of MOS, End-to-end delay through extensive simulations. Results are provided with valid discussions. Based on the observation, we propose an Adaptive VoIP (AdVoIP) algorithm that may be used in any real life VoIP network for further enhancement of the performance. The adaptive algorithm may use RTCP Receiver Reports to assess the network conditions in real wireless scenarios.

Optimization technique for configuring IEEE 802.11b access point parameters to improve VoIP performance

The performance of wireless LANs is greatly affected by path loss, RF interference and other sources of signal attenuation in addition to network congestion. The primary factors involved in effective real-time communication, namely delay and loss, must be within certain controlled limits in such a scenario. In this paper, we analyze the various factors driving IEEE 802.11b access points through extensive simulations and thereafter develop an optimization technique to configure the parameters of the Access Point. We simulate our test bed scenario and apply the developed algorithm. Finally, we implement the configured parameters in our testbed to provide optimum Voice over IP (VoIP) performance. Simulation and measured results have been included.

Implementation of RSA security protocol for sensor network security: Design and network lifetime analysis

Application of Wireless sensor network (WSN) is increasing in a rapid speed. As sensor networks may interact with sensitive data and operate in hostile unattended environments, it is imperative that security concern be addressed from the beginning of the system. But sensor networks also introduce severe resource constraints due to their lack of data storage and power. Both of these represent major obstacles to the implementation of traditional computer security techniques in a wireless sensor network. There has to be some compromise between the security and the energy. Asymmetric protocol like RSA has not been implemented due to high power constrain and for memory issue. In this paper, we have shown that RSA can be implemented for sensor in an efficient manner by using optimized computation. We have simulated the protocol in NS2.34 platform. The energy requirement gives an optimistic result quite similar to symmetric protocol energy requirement for sensor.