Vijay Shanker Tripathi

Bandwidth Allocation Based on Traffic Load and Interference in IEEE 802.16 Mesh Networks

This paper introduces a traffic load and interference based bandwidth allocation (TLIBA) scheme for wireless mesh network (WMN) that improves the delay and throughput performance by proper utilization of assigned bandwidth. The bandwidth is allocated based jointly on traffic load and interference. Then a suitable path is selected based upon the least routing metric (RM) value. Simulation results are presented to demonstrate the effectiveness of the proposed approach which indicates higher bandwidth utilization and throughput as compared with existing fair end-to-end bandwidth allocation (FEBA).

Dual-Band Microstrip Patch Antenna Miniaturization Using Metamaterial

A dual-band microstrip patch antenna is designed and analyzed using metamaterial artificial substrate. Metamaterial based substrate is designed using Square Split Ring Resonator (SSRR) and Wire Strip. The antenna is tuned to work at two resonating frequencies in the frequency range from 1 GHz to 4 GHz depending on the geometric specifications of SSRR, strip line, radiating patch, and feed location point. Proposed antenna provides good return loss behavior at both resonating frequencies. The obtained VSWR at both resonating frequencies is very much near to 1. Proposed antenna covers applications in mobile communication and Wi-MAX. Proposed patch antenna is compared with the conventional patch antenna, which shows the significant miniaturization as compared to conventional patch antenna.

Inverted Z and circular slot patch antenna for WLAN and WiMAX

In this paper, a compact multiband microstrip patch antenna with Z-shaped slots in the radiating patch is proposed. The antenna has a rectangular radiating patch on the top of the substrate and a ground plane on the bottom of it. A coaxial probe feeding is located along the orthogonal axis of the square patch radiator. Z-shaped slot on radiating patch gives a wider bandwidth with better return-loss. Various slots of this antenna are compared, and an optimized design is presented. Exploitation of Z-shape slot in antenna design makes the patch antenna flexible in terms of generating resonances and bandwidth as an order of the slots is increased. Several properties of the antenna such as impedance bandwidth, VSWR are presented.

Shared power allocation among subcarriers of OFDM systems

Orthogonal frequency division multiplexing (OFDM) has several properties which make it an attractive modulation scheme for high speed wireless transmission links. In this paper, a novel power sharing technique is proposed for different users to improve the system performance. The proposed technique is based on use of variable amplitude of subcarriers (VAS). Power can be increased to the users who are crossing the reference boundary (RB) and moving farther towards foot print (FP) of a cell. In this way the users having weak SNR can sustain their call even in multipath fading environment. Assuming knowledge of the instantaneous channel gain estimation for all users, we propose an OFDM dynamic adaptive subcarriers scheme to maintain optimum SNR level of the subchannels which are in deep fade. Simulation results show that the performance of the proposed algorithm is much better than that of other algorithms.

A novel sensing and primary user protection algorithm for cognitive radio network using IoT

Abstract Internet of things (IoT) is a technology which facilitates passive devices to participate in active communication. In the presented work the radio frequency identification (RFID) system is used to access information from passive primary receiver (PURx). This inspires to develop a novel sensing algorithm along with PURx protection from harmful transmissions of cognitive radio (CR) nodes in CR network. The novelty in the sensing and protection lies in the approach of accessing information from primary users. Here a CR node can detect occupancy of primary channel from both, primary transmitter (PUTx) end as well as from PURx end on the basis of relative distance. For protection of PURx a novel power control algorithm is proposed and implemented. The results indicate less energy is needed to run the network along with a notable improvement in average throughput and reduction in delay for increasing amount of CR traffic.

Performance Evaluation of Timing Estimation Technique Using Extended Cyclic Prefix for Correlation Sequence for OFDM Systems

This paper presents an analysis of symbol timing offset (STO) estimation method for orthogonal frequency division multiplexing systems. The proposed method does not require any preamble and with the use of available cyclic prefix (CP) samples we have proposed an extended CP. The extended CP is used to exploit more number of correlation products in correlation sequence so that a more accurate starting point of any symbol can be estimated. A simplified maximum likelihood estimation process for proposed timing estimation technique is given which enables us much more accurate timing estimate due to decreased error variance. The performance of the proposed method is evaluated in terms of mean square error of timing estimator against different signal to noise ratio values and in terms of error distribution of the estimators with and without the effect of carrier frequency offset in various channel scenarios such as AWGN, HIPERLAN/2A and HIPERLAN/2E. Simulation results shows that proposed method has significantly better performance compared to the CP based method for STO estimation.

Microstrip Patch Antenna Miniaturization Using Planar Metamaterial Unit Cell

A Microstrip patch antenna using planar metamaterial unit cell is designed, simulated and analyzed. The metamaterial unit cell is consisting of an interdigital capacitor and a complementary split-ring resonator (CSRR) slot. The antenna is tuned to work efficiently in the frequency range from 3 GHz – 5GHz depending on the geometric specifications of antenna and interdigital finger length. Proposed antenna provides good return loss behavior. The VSWR obtained in this band is very much near to 1. It covers many applications including mobile communication. This Antenna is compared with the conventional patch antenna, which shows the significant miniaturization as compared to conventional patch antenna.

A compact triple-band microwave filter using symmetrically placed stub-loaded open-loop resonators

ABSTRACT In this paper, symmetrically placed stub-loaded open-loop resonators with magnetic coupling are used to design compact triple-band band pass filter (BPF) with improved insertion loss at passbands. Three bands of the proposed triple-band stub-loaded open-loop resonator filter are achieved by tuning length and position of open shunt stub which is connected with open-loop resonators. A lossless transmission line model is used to calculate the resonator properties. Theoretical design procedures are verified with an example of triple-band BPF design. Three passbands at 2.85, 5.9 and 8.15 GHz are achieved with reduced insertion loss. The insertion loss measured at first, second and third passbands are 0.47, 0.77 and 1.41 dB, respectively. First passband 2.76–2.9 GHz is used for the airport surveillance radar system and weather monitoring system. Second frequency band 5.82–6.16 GHz is used for the intelligent transportation system and third band 8.1–8.7 GHz is useful for satellite communication.

Design and Analysis of Small Planar Antenna Based on CRLH Metamaterial for WSN Application

In this paper a small antenna is proposed for wireless sensor network applications in the frequency band of 5 GHz to 15 GHz. Wireless Sensor Networks (WSN) is having significant attention due to their numerous features nowadays. The most important component in sensor is its TX/RX antenna. In this design a new efficient CRLH based DNG metamaterial antenna is proposed. The design of the unit cell of these antennas is based on the composite right/left-handed (CRLH) transmission line model. Antenna1 used two patches and obtained results are compared with antenna2 with four patch. In this paper, we introduce a new method of design of CRLH metamaterial antennas to tackle the above problem using CRLH mushroom structure. The results of antenna2 show improvements over antenna1 in gain and bandwidth. By employing CRLH geometry, an overall size reduction of 65% was achieved compared to the conventional rectangular patch antenna. The proposed antenna can be easily built in a miniaturized wireless sensor network (WSN). RogersRT/Duroid 5880 is taken as substrate with thickness 1.572 mm and relative permittivity 2.2. The bandwidth of this antenna less than 10 dB is 700 MHz and the percentage of the bandwidth is 6.1%. The antenna characteristics, such as return loss and VSWR achieved by the proposed structure are plotted.

Compact circularly-polarized microstrip patch antenna on Reactive Impedance Substrates

A reduced-size wideband single-feed circularly polarized microstrip patch antenna is presented for telemetry applications in S-band around 2.4 GHz. In this paper we compare the performance of microstrip patch antenna designed over two layer conventional substrate with different relative permittivity and different height and over a Reactive Impedance Substrate with slot, both of them being constituted with the same substrate layers. In particular we optimize the feeding position and number of reactive elements upon the antenna bandwidth and axial ratio. The proposed structure consists of a slot-loaded patch antenna printed over an optimized metamaterial-inspired reactive impedance substrate (RIS). We demonstrate, step by step, the main role of each antenna element by comparing numerically the performance of various antenna configurations, antenna over a single layer substrate or dual-layer substrate, patch without slot or slot-loaded patch, antenna with or without RIS. The final optimized structure exhibits an axial-ratio bandwidth of about 15% and an impedance bandwidth better than 10%, which is much wider than the conventional printed antenna on the same materials. The return loss pattern of different microstrip patch antenna with and without RIS arrangement is also compared using HFSS simulation software.