Leeladhar Malviya

A 2 × 2 Dual - Band MIMO Antenna with Polarization Diversity for Wireless Applications

A compact 2×2 dual-band MIMO antenna is proposed with polarization diversity technique for present wireless applications. The proposed design combines the horizontally and vertically polarized radiating elements. The effect of mutual coupling between radiating elements is reduced by partially stepped ground (PSG) and by the orthogonal placement of antenna elements. The whole configuration is designed over a substrate of size 70 × 70 mm 2 . The measured frequency bands extend from 2.408 to 2.776 GHz and 4.96 to 5.64 GHz frequencies with SWR < 2. The measured isolation is more than 21 dB between adjacent and diagonal ports. The measured peak gains at 2.54 GHz, and 5.26 GHz resonant frequencies are 3.98 dBi and 4.13 dBi, respectively. The designed MIMO covers LTE bands (7/38/41), WLAN bands (2.4/5.2 GHz), and WiMAX band (2.5/5.5 GHz). The diversity performances in terms of peak gain, ECC, and MEG have also been reported.

Circularly Polarized 2×2 MIMO Antenna for WLAN Applications

A 2 × 2 circularly polarized (CP) MIMO antenna is proposed to resonate at 5.8 GHz IEEE 802.11 WLAN band for non-line of sight (NLOS) communication. The proposed design achieves circular polarization with two optimized 90◦ apart rectangular slots etched at the center of a truncated rectangular patch. The proposed MIMO covers 5.49–6.024 GHz frequency band. The achieved isolation between two ports is more than 33 dB. The gain at the 5.8 GHz resonant frequency is 5.34 dBi. The diversity performance in terms of gain, ECC, and MEG has been reported.

Simulation Based Comparison of Different Modulation Schemes for Mobile WiMAX Using TCP and its Variants

Adaptive modulation enables a WiMAX system to optimize the throughput based on propagation conditions. IEEE 802.16 (WiMAX) system support BPSK, QPSK, 16-QAM and 64-QAM and the access scheme is OFDM. This paper presents the performance of different variants of transmission control protocols with different modulation schemes when density of mobile nodes changes.

Low Magnitude Edge Detection Algorithm

Edge detection are very important in the digital world to find the information about an object like range, boundaries, level,, hidden and missing fields or edges etc. There are very few approaches and algorithms to show the finer details of an object. The proposed edge detection technique explores the hidden edges in a very simpler manner.

MIMO antennas with diversity and mutual coupling reduction techniques: a review

Multiple input multiple output (MIMO) antenna is at core of the presently available wireless technologies. The design of MIMO antennas over a limited space requires various approaches of mutual coupling reduction, otherwise gain, efficiency, diversity gain, and radiation patterns will be severely affected. Various techniques have been reported in literature to control this degrading factor and to improve the performance of the MIMO antennas. In this review paper, we have carried out an extensive thorough investigation of diversity and mutual coupling (correlation) reduction techniques in compact MIMO antennas.

Four Element Planar MIMO Antenna Design for Long-Term Evolution Operation

ABSTRACT Four element (2 × 2) planar multi-input multi-output (MIMO) antenna design is proposed for long-term evolution applications for operating bands 1 and 4. The design combines 180° phase reversed and phase rotated antenna elements. Presented design integrates the effect of pattern and space diversity techniques for common return-losses and isolations at different (or between) ports. The fabricated antenna utilizes the space of 68 × 98 mm2 on low cost FR-4 dielectric substrate. The proposed design with VSWR of <2 exhibits −10 dB impedance bandwidth in the range of 1.66–2.17 GHz. More than 10 dB of isolation among all the radiating elements of MIMO is recorded in simulation and measured cases. The measured peak gain in considered frequency spectrum is better than 2.5 dBi. The diversity performance explores the effect of peak gain, envelope correlation coefficient (ECC), mean effective gain, and directivity on the presented design.

Proximity coupled MIMO antenna for WLAN/WiMAX applications

MIMO is the key to the wireless communication to solve the multipath propagation related issues for 4G technologies. A proximity coupled compact MIMO antenna is proposed for WLAN/WiMAX applications. The overall size of the proposed MIMO on the low cost FR-4 dielectric substrate is 39.63 × 82.15 mm2. The measured result shows more than 10 dB of in-band isolation, envelope correlation coefficient of 0.1, and gain of more than 2.75 dBi in the whole band.

Design of a compact MIMO antenna with polarization diversity technique for wireless communication

The present wireless communication with MIMO antennas, takes the advantages of high data rate and high capacity and requires dual polarization for the coverage of vertically and horizontally polarized signals. A G shaped polarization diversity MIMO antenna with ground modification techniques and perfect boundary conditions is proposed to resonate at 2.47 GHz for wireless communication. It covers 2.39-2.7126 GHz of common frequency spectrum for WLAN, WIMAX, and LTE bands. The size of the FR4 substrate used for MIMO antenna is 0.58λ × 0.29λ mm2. The proposed design shows less than -23 dB of mutual coupling, peak gain of more than 2.5 dB for each antenna, and common bandwidth of 32.26% respectively.

Pattern diversity based MIMO antenna for low mutual coupling

A highly isolated MIMO antenna is proposed with ground modification and pattern diversity techniques to resonate at 3.4 GHz frequency. It covers WLAN, WIMAX, LTE-FDD 22 band, and LTE-TDD 42/43 bands. The designed antenna achieves exact complementary radiation patterns, which confirms to the pattern diversity. The measured result shows 48.4 dB of isolation, and 3.66 dB of gain at resonant.

Mobile Adhoc Network under the Adaptive TCP Variants Techniques for Maximization of Throughput

is an adhoc network which is set up by wireless mobile computers (or nodes) which moves randomly in the places that have no network infrastructure or hard to reach location. Since the nodes communicate with each other to gather network information. They cooperate by forwarding data packets to other nodes in the network. In wireless adhoc networks, cooperation between nodes takes place so that they route each others packet till it reaches destination. Hence they are exposes to a wide range of security attacks. Also because the vulnerability of routing protocols, the wireless ad- hoc networks have to face several security risks. One of these attacks is the Blackhole Attack against network integrity which absorbs all data packets in the network. Since the data packets do not reach the destination node due to Blackhole attack. As a result data loss will occur. In this paper, we simulated the Black hole attack in various wireless ad-hoc network scenarios: with Blackhole attack and without Blackhole attack and comparison of existing TCP variants: TCP, FullTCP, Reno, Reno/Asym, New Reno, New Reno/Asym, Asym, Sack, Fack and Vegas. The impact of Blackhole attack on the performance of MANET is evaluated on the basis of those two scenarios. The measurements were taken to analyze network performance are Throughput, Packet Delivery Ratio and Total Dropped Packet. The simulation was done by using network simulator (NS-2.34). Keywordsad-hoc network (MANET), TCP variants, routing protocol, network security, Blackhole attack, NS-2.