scholarly journals Joint Timing and Frequency Synchronization Using Convolutional Neural Network in WLAN Systems

2021 ◽  
Vol 12 (6) ◽  
pp. 531-537
Author(s):  
Eui-Soo Lee Et.al
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Frequency Offset ◽  
Area Network ◽  
Ofdm Systems ◽  
Frequency Offsets

In wireless communication systems, the performance of the receiver is very sensitive to time and frequency offsets. In particular, orthogonal frequency division multiplexing (OFDM) systems are highly vulnerable to those offsets due to inter-carrier interference (ICI) and inter-symbol interference (ISI). To solve this problem, wireless local area network (WLAN) systems transmit a preamble for synchronization. In this paper, we propose a joint time and frequency offsets estimation technique based on convolutional neural network (CNN) for WLAN systems. In the proposed technique, the correlation between the received signal and the transmitted preamble is performed first. Then the frequency offset is coarsely compensated by several hypothesized offsets. The compensated signals are inputted to the proposed CNN and the CNN predicts the time and frequency offsets. The estimation performance is examined through computer simulation. According to the results, the proposed time offset estimator shows 3 dB to 6 dB performance gain, and the frequency offset estimator shows much lower root mean square error (RMSE) performance than the conventional technique at low SNRs

scholarly journals Performance analysis of IEEE 802.11ac based WLAN in wireless communication systems

2019 ◽  
Vol 9 (2) ◽  
pp. 1131 ◽  
Author(s):  
A. Z. Yonis
Keyword(s):  
Communication Systems ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Multiple Input Multiple Output ◽  
Local Area ◽  
Area Network ◽  
Data Rates ◽  
Input Multiple Output ◽  
Ieee 802.11Ac ◽  
5 Ghz

<p><span lang="EN-US">IEEE 802.11ac based wireless local area network (WLAN) is emerging WiFi standard at 5 GHz, it is new gigabit-per-second standard providing premium services. IEEE 802.11ac accomplishes its crude speed increment by pushing on three distinct measurements firstly is more channel holding, expanded from a maximum of 80 MHz up to 160 MHz modes. Secondly, the denser modulation, now using 256-QAM, it has the ability to increase the data rates up to 7 Gbps using an 8×8 multiple input multiple output (MIMO). Finally, it provides high resolution for both narrow and medium bandwidth channels. This work presents a study to improve the performance of IEEE 802.11ac based WLAN system.</span></p>

Fractal-based triangular bandpass filter with a notched band for interference rejection in wideband applications

Circuit World ◽  
2019 ◽  
Vol 45 (3) ◽  
pp. 141-147 ◽  
Author(s):  
Karthie S. ◽  
Salivahanan S.
Keyword(s):  
Communication Systems ◽  
Bandpass Filter ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Low Cost ◽  
Area Network ◽  
Interference Rejection ◽  
Content Type ◽  
Notched Band ◽  
Low Cost Substrate

Purpose This paper aims to present the design of a novel triangular-shaped wideband microstrip bandpass filter implemented on a low-cost substrate with a notched band for interference rejection. Design/methodology/approach The conventional dual-stub filter is embedded with simple fractal-based triangular-circular geometries through various iterations to reject wireless local area network (WLAN) signals with a notched band at 5.8 GHz. Findings The filter covers a wide frequency band from 3.1 to 8.8 GHz and has a fractional bandwidth of 98 per cent with the lower passband of 57.5 per cent and upper passband of 31.6 per cent separated by a notched band at 5.8 GHz. The proposed wideband prototype bandpass filter is fabricated in FR-4 substrate using PCB technology and the simulation results are validated with measurement results which include insertion loss, return loss and group delay. The fabricated filter has a sharp rejection of 28.3 dB at 5.8 GHz. Measured results show good agreement with simulated responses. The performance of the fractal-based wideband filter is compared with other wideband bandpass filters. Originality/value In the proposed work, a fractal-based wideband bandpass filter with a notched band is reported. The conventional dual-stub filter is deployed with triangular-circular geometry to design a wideband filter with a notched band to suppress interference signals at WLAN frequency. The proposed wideband filter exhibits smaller size and better interference rejection compared to other wideband bandpass filter designs implemented on low-cost substrate reported in the literature. The aforementioned wideband filter finds application in wideband wireless communication systems.

A Wireless Local Area Network Channel Estimation Scheme

2013 ◽  
Vol 443 ◽  
pp. 462-467
Author(s):  
Xiang Bin Gao
Keyword(s):  
Channel Estimation ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area ◽  
Area Network ◽  
Ofdm Systems ◽  
Network Systems ◽  
Ieee 802.11A ◽  
Estimation Scheme ◽  
Network Channel

In this paper, a robust channel estimation scheme is proposed for the OFDM based wireless local area network systems. The proposed channel estimation scheme has been done targeting the IEEE 802.11a standard [, but it can be extended to other packet-based OFDM systems. A robust channel estimation scheme is proposed for the OFDM-based wireless local area network systems. Performance evaluation shows that the WLAN system with the proposed channel estimation scheme is with practical system performance under harsh fading channel.

scholarly journals Design of A Dual-Wide Band BPF Utilizing Parallel Coupled Microstrip Lines and A Centered Arrow-Shaped Resonator

2020 ◽  
Vol 23 (2) ◽  
pp. 153-158
Author(s):  
Ahmed Lateef Khudaraham ◽  
Dhirgham Kamal Naji
Keyword(s):  
Communication Systems ◽  
Satellite Communication ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Wide Band ◽  
Local Area ◽  
Area Network ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Strip Lines

This paper presents a dual wide-band band pass filter (DWB-BPF) by using two parallel, symmetrical micro-strip lines loaded by a centered resonator, consisting of a T- and a triangle-shaped geometry, attached at the lower and upper ends, respectively. The filter reveals good performance and both the passbands can be independently controlled by adjusting specific parts of the filter. The proposed BPF is simulated by using CST microwave studio package and the simulated result is verified experimentally with good agreement between the two results.  The fabricated prototype BPF demonstrates two passbands located at 2.3 GHz and 6.35 GHz center frequencies with 39% and 23.6% of 3-dB fractional bandwidth (FBW), respectively and a good insertion and return losses. The designed BPF can be targeted for wireless local area network (WLAN), WIFI and satellite communication systems.

The Effectiveness of Wi-Fi-Network Technology on Campuses and Residences for an Improved Learning Experience and Engagement

Mousaion ◽  
2021 ◽  
Vol 39 (1) ◽  
Author(s):  
Kenneth Nwanua Ohei ◽  
Roelien Brink
Keyword(s):  
Higher Education ◽  
Communication Systems ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area ◽  
Easy Access ◽  
Area Network ◽  
Effective Learning ◽  
Information And Communication ◽  
Improved Learning

The information and communication technology revolution is broadly recognised for its fundamental role in the effective operation of higher education institutions. There is a need to understand the way in which wireless local area networks at universities are viewed by registered users, the people that develop, implement and maintain these networks, and those planning on adopting these networks. The study’s objective is to unravel the usefulness of these networks in a higher education environment to promote effective learning engagements at campuses of the University of Johannesburg in South Africa. Universities provide Wi-Fi network initiatives on campuses to create an effective learning environment, and wireless local area network connections at universities mean that Wi-Fi-enabled devices can be leveraged for educational purposes. The provision of Wi-Fi-enabled computers, mobile devices and electronic gadgets has revolutionised the realm and methods of communication, which is channelled towards improving and enhancing internet coverage on campuses and at student residences. This study explores the effectiveness of Wi-Fi networks and hotspots on campuses and at student residences to improve students’ learning engagement. The study used mixed-research methods, including a document analysis to gather information from information and communication systems and a survey to gather responses from the respondents. The findings suggest that Wi-Fi availability at universities is perceived as useful and effective since students benefit from a range of improved learning experiences, easy access to educational content, enhanced performance, and quality and education delivery.

scholarly journals Flexible Wearable Composite Antennas for Global Wireless Communication Systems

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6083
Author(s):  
Rui Zhang ◽  
Jingwen Liu ◽  
Yangyang Wang ◽  
Zhongbao Luo ◽  
Binzhen Zhang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Wireless Communication ◽  
Loss Tangent ◽  
Communication Systems ◽  
Large Scale ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Wireless Body Area Network ◽  
Wireless Communication Systems ◽  
Area Network

Although wearable antennas have made great progress in recent years, how to design high-performance antennas suitable for most wireless communication systems has always been the direction of RF workers. In this paper, a new approach for the design and manufacture of a compact, low-profile, broadband, omni-directional and conformal antenna is presented, including the use of a customized flexible dielectric substrate with high permittivity and low loss tangent to realize the compact sensing antenna. Poly-di-methyl-siloxane (PDMS) is doped a certain proportion of aluminum trioxide (Al2O3) and Poly-tetra-fluoro-ethylene (PTFE) to investigate the effect of dielectric constant and loss tangent. Through a large number of comparative experiments, data on different doping ratios show that the new doped materials are flexible enough to increase dielectric constant, reduce loss tangent and significantly improve the load resistance capacity. The antenna is configured with a multisection microstrip stepped impedance resonator structure (SIR) to expand the bandwidth. The measured reflection return loss (S11) showed an operating frequency band from 0.99 to 9.41 GHz, with a band ratio of 146%. The antenna covers two important frequency bands, 1.71–2.484 GHz (personal communication system and wireless body area network (WBAN) systems) and 5.15–5.825 GHz (wireless local area network-WLAN)]. It also passed the SAR test for human safety. Therefore, the proposed antenna offers a good chance for full coverage of WLAN and large-scale development of wearable products. It also has potential applications in communication systems, wireless energy acquisition systems and other wireless systems.

scholarly journals Hexagonal Printed Monopole Antenna with Triple Stop Bands for UWB Application

2019 ◽  
Vol 38 (2) ◽  
pp. 335-340 ◽  
Author(s):  
Muhammad Irfan Khattak ◽  
Muhammad Irshad Khan ◽  
Zaka Ullah ◽  
Gulzar Ahmad ◽  
Amad Khan
Keyword(s):  
Electromagnetic Interference ◽  
Communication Systems ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Monopole Antenna ◽  
Ultra Wideband ◽  
Area Network ◽  
International Telecommunication Union ◽  
Printed Monopole Antenna ◽  
Printed Monopole

Inherently UWB (Ultra Wideband) communication systems comes with interference problem with some if the existing narrowband communication systems. These bands are stopped with the help of band-stop filter in order to reduce electromagnetic interference However, the complexity and limitations are increased due to these filters, hence this solution is turned down in those applications where design complications and complexity is of concern. Introducing various slots of specific shapes and exact dimensions however, have solved this issue for the researchers around the world. This paper presents a hexagonal PMA (Printed Monopole Antenna) with triple stop bands. The antenna is used for UWB application. The antenna is stopped the WiMAX (Worldwide Interoperability for Microwave Access), WLAN (Wireless Local Area Network) and ITU (International Telecommunication Union) bands. The antenna dimensions are 30x28x16 mm3. FR4 is used between ground and radiating patch with relative permittivity of 4.4. The VSWR (Voltage Standing Wave Ratio) is less than 2 between 3-11 GHz except WiMAX (3.1-3.7 GHz), WLAN (5.1-5.8 GHz) and the ITU frequency band (7.95-8.4 GHz). The antenna is design in CST software.

Tunable dual-band resonators for communication systems

2010 ◽  
Vol 2 (3-4) ◽  
pp. 245-253 ◽  
Author(s):  
David Girbau ◽  
Antonio Lázaro ◽  
Albert Pérez ◽  
Esther Martínez ◽  
Lluís Pradell ◽  
...  
Keyword(s):  
Communication Systems ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area ◽  
Dual Band ◽  
Area Network ◽  
Resonator Design ◽  
Depth Analysis ◽  
Stepped Impedance Resonator ◽  
Constant Section

This paper proposes the design of tunable dual-band resonators for multi-band multi-standard systems. The main objective is to provide frequency tunability in the second resonance while maintaining the first resonance fixed. To this end, two tunable resonators are proposed: the capacitive-loaded stepped-impedance resonator and the capacitive-loaded hole resonator. The work is divided into two main parts. In the first part, an in-depth analysis of the capacitive-loaded stepped-impedance resonator (SIR) structure is done; it provides analytical closed-form design equations that ease the resonator design in contrast to the several approaches available in the literature to date. The analysis is also particularized to the case of the capacitive-loaded constant-section resonator and extended to the capacitive-loaded hole resonator. In addition, a study of the quality factor in capacitively tuned SIRs is also provided. In the second part, resonators are integrated in three dual-band tunable filters, one based on the capacitive-loaded constant-section resonator, another one on the capacitive-loaded SIR, and finally on the capacitive-loaded hole resonator. Two of these filters demonstrate operation in wireless local-area network frequency bands, with a fixed first band at 2.45 GHz and a second band which can be tuned between 5.75 and 5.25 GHz.

scholarly journals Wireless LAN-Based CSI Monitoring System for Object Detection

Electronics ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 290 ◽  
Author(s):  
Tomoki Murakami ◽  
Masahiko Miyazaki ◽  
Shigemi Ishida ◽  
Akira Fukuda
Keyword(s):  
Object Detection ◽  
Monitoring System ◽  
Wireless Lan ◽  
Orthogonal Frequency Division Multiplexing ◽  
Wireless Local Area Network ◽  
Environmental Changes ◽  
Local Area Network ◽  
Detection Accuracy ◽  
Target Area ◽  
Area Network

Sensing services for the detection of humans and animals by analyzing the environmental changes of wireless local area network (WLAN) signals have attracted attention in recent years. In object detection using WLAN signals, a widely known technique is the use of time changes in received signal strength indicators that are easily measured between WLAN devices. Utilizing channel response, including power and phase values per subcarrier on multiple input multiple output (MIMO), the orthogonal frequency division multiplexing transmission was researched as channel state information (CSI) to further improve detection accuracy. This paper describes a WLAN-based CSI monitoring system that efficiently acquires the CSI of multiple links in a target area where multiple CSI measuring stations are distributed. In the system, a novel CSI monitoring station captures wireless packets sent within the area and extracts CSI by analyzing the packets on the sounding protocol, specified by IEEE 802.11ac. The paper also describes the system configuration and shows that indoor experimental measurements confirmed the system’s feasibility.

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