Wireless LAN Systems Research Articles

Radio Resource Allocation Using Multi-AP Coordination Considering Requirements for Video Transmission in Wireless LAN system

Radio Resource Allocation Using Multi-AP Coordination Considering Requirements for Video Transmission in Wireless LAN system

Communication Systems: an Overview of Past, Present and Futuristic Outlook

In contemporary times, communication systems have become the major drivers of globalization and trade facilitation. From its simple beginning to the more recent 5G and 6G technologies which are at various stages of development and applications, capable of entrenching the era of the Internet of Things (IoT), advancing Machine-to Machine (M-2-M) integration, and further revolutionizing the speed of seamless communication between smart devices. Significant advancements have also been achieved in the area of auxiliary technology interfaces incorporated into mobile communication systems such as the wireless LAN (Wi-Fi), Bluetooth, Infra-Red (IR), and sundry communication systems operating at the higher frequency bands of the electromagnetic spectrum. Against this backdrop, this work reviewed some communication systems highlighting their technology and developmental trends. Furthermore, it attempts to accurately forecast the probable direction of future advancements in communication systems, based on a painstaking trend and pattern analysis of the technological improvements of Bluetooth, Radar, and Wi-Fi technologies and some other communication systems in the past decade.

MODELING OF A DIGITAL COMMUNICATION SYSTEM WITH INTERFERENCE-RESISTANT CODING OVER DELAYED MULTIPATH CHANNELS FOR A FIXED WIRELESS ACCESS SYSTEM


 
 
 In this study, an analysis of the performance of a digital communication system was conducted to improve the efficiency of the communication channel. The system was de- signed and evaluated in the MatLab/Simulink environment, specifically for the transmission of binary data in a multipath channel with static fading. One of the main advantages of this system is its ability to provide high noise immunity, even in the presence of noise, interference, and signal delays. The performance of the system was investigated in terms of bit error rate (BER) over both an additive white Gaussian noise (AWGN) channel and a multipath Rayleigh fading channel. The study also considered the impact of inter-symbol interference (ISI) and explored different parameters for a static channel, resembling a wireless LAN system based on IEEE 802.11 (as defined by Rec ITU-R M.1225). This study uses a solution to suppress inter-symbol interference using cascading coding (convolutional turbo codes with Reed Solo- mon code), Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT), amplifiers at the transmitter side and normalizer at the receiver side, by regulating the amplification ratios of transmitter and receiver sides. Modeling of a digital communication system for a wide-band fixed wireless LAN system (for Indoor office and Outdoor to indoor systems) has been performed. The modeling outcomes show that the applied method provides a good per- formance improvement in channels with ISI with static fading.
 The application of cascading coding (turbo code together with RS code), amplifiers, and FFT on the transmitter side, and IFFT on the receiver side will eliminate the effects of inter-symbol interference on digital signals in a multipath channel with static fading (as defined by Rec. ITU-R M.1225 for internal and external transmission systems) for wireless fixed systems.
 
 

Orthogonally crossed triangular monopole antenna for octave band frequencies

ABSTRACT This paper proposes an orthogonally positioned inverted triangular monopole antenna over a compact plane reflector with stable radiation pattern for octave band of frequencies. Two triangles are placed crossed and orthogonal to each other to obtain nearly uniform omni-direction radiation pattern. The antenna is placed over a square reflector exhibits 73% bandwidth at (4.5 GHz). The measured impedance bandwidth and radiation pattern of the antenna match well with Finite Element Method (FEM) and Method of Moments (MOM) analysis of the structure. The antenna is novel in its orthogonal design and the triangles fed differently with compact reflector. The designed octave band planar antenna (3.0–6.5 GHz) has applications in Wireless LAN and intelligent transportation systems (ITS). The compact antenna design with uniform radiation pattern is used as radiator inside a room and cabinets for RF isolation measurements.

Wireless Networks Encryption by Simulation of Attacks

Wireless LANs widespread use is attributable to a combination of factors, including simple construction, employee convenience, connection selection convenience, and the ability to support continual movement from residences to large corporate networks. For organizations, however, the availability of wireless LAN means an increased danger of cyberattacks and challenges, according to IT professionals and security specialists. This paper examines many of the security concerns and vulnerabilities associated with the IEEE 802.11 Wireless LAN encryption standard, as well as typical cyber threats and attacks affecting wireless LAN systems in homes and organizations, and provides general perception of weaknesses for home and business users.

A High-Speed Channel Assignment Algorithm for Dense IEEE 802.11 Systems via Coherent Ising Machine

This letter reports on an ultra-fast and accurate channel assignment approach using a coherent Ising machine (CIM) for dense wireless LAN (WLAN) systems. CIM is a laser-based high-speed hardware approach for solving Ising problems using optoelectronic features. We formulate the total-throughput maximization problem for large-scale centralized WLAN systems as a combinatorial optimization problem. Subsequently, the problem is converted into an Ising problem to be optimized via a CIM. Simulation results reveal that the CIM can improve the total throughput performance and give results in a very short time (millisecond order).

Coordinated Scheduling of 802.11ax Wireless LAN Systems Using Hierarchical Clustering

Coordinated Scheduling of 802.11ax Wireless LAN Systems Using Hierarchical Clustering

Experimental Validation of Link Quality Prediction Using Exact Self-Status of Mobility Robots in Wireless LAN Systems

Autonomous mobility machines, such as self-driving cars, transportation robots, and automated construction machines, are promising to support or enrich human lives. To further improve such machines, they will be connected to the network via wireless links to be managed, monitored, or remotely operated. The autonomous mobility machines must have self-status based on their positioning system to safely conduct their operations without colliding with other objects. The self-status is not only essential for machine operation but also it is valuable for wireless link quality management. This paper presents self-status-based wireless link quality prediction and evaluates its performance by using a prototype mobility robot combined with a wireless LAN system. The developed robot has functions to measure the throughput and receive signal strength indication and obtain self-status details such as location, direction, and odometry data. Prediction performance is evaluated in offline processing by using the dataset gathered in an indoor experiment. The experiments clarified that, in the 5.6 GHz band, link quality prediction using self-status of the robot forecasted the throughput several seconds into the future, and the prediction accuracies were investigated as dependent on time window size of the target throughput, bandwidth, and frequency gap.

A Novel Drone's Height Control Algorithm for Throughput Optimization in Disaster Resilient Network

In recent years, unmanned aerial vehicle (Unmanned Aircraft Vehicles) networks using unmanned aerial vehicles called UAVs have been studied as one of the means for constructing temporary wireless communication networks in the event of a disaster. In this paper, we investigate a drone network using a rotor UAV called a drone that can be hovered and easy to construct a network. On the other hand, it is expected that the distribution of communication terminals on the ground will be uneven because people concentrate in specific places such as evacuation centers in the actual disaster area. Traffic concentrates on specific drones covering the area where terrestrial terminals are dense, then throughput per terminal decreases. In order to solve this problem, we propose a method to control the height of drone according to the traffic and to select the transmission method by link adaptation, well-known in wireless LAN and cellular systems. By computer simulation, the average throughputs per ground terminal for the heights of the drones are shown quantitatively, and the effectiveness of the proposed method is clarified.

A Reactive Reporting Scheme for Distributed Sensing in Multi-Band Wireless LAN System

A Reactive Reporting Scheme for Distributed Sensing in Multi-Band Wireless LAN System

Signal Detection Method for Interference From Inverter Microwave Ovens in WLAN Systems

Inverter microwave ovens (inv. MWOs) are day-to-day appliances that can severely interfere with 2.4 GHz wireless LAN (WLAN) devices. However, interference is avoidable by using a signal detection method that recognizes MWO signals. In our previous work, we have proposed a specialized detection method that recognizes characteristic power levels of leakage signals from inv. MWOs, which drastically vary depending on the switching of the inverter. Using experimental MWO data obtained in a shielded room, we also demonstrated that the proposed method correctly detects inv. MWO signals with robustness against different products, different receiving environments, and the presence of other signals. In this paper, we begin with a discussion of the influence of MWO interference, and then review process and evaluation of the proposed method, along with new additional analysis. By simplifying the process, we also provide a test chip implementation for method realization and real-time signal detection to enhance the reliability of WLAN systems. Finally, we use the test chip to show that it is also possible to detect jammer signals.

Tri-band MIMO Antenna for WLAN, WiMAX and Defence System & Radio Astronomy Applications

In this paper, an efficacious and impermeable undeviating MIMO consist of 70 x 50 x 0.4 mm3 is used for WLAN, defence system & radio astronomy and WiMAX applications. To keep in order abandoning the reactive connection between the antennas, a neutralizing line is connected between the two symmetrical radiating elements. Another technique to reducing isolation (mutual coupling) between the antennas, four small slits of small size are etched onto to the ground plane. This has resulted in the proposed antenna giving a good bandwidth at the three resonant frequencies of (3.2–3.7 GHz) for Wireless LAN, (5.1–5.6 GHz) WiMAX and (6.7–7.5 GHz) defence system & radio astronomy applications with |S11|< -10 dB and mutual coupling |S12|< -20 dB for the entire operating band. The simulation results and measured results demonstrate that tri-band MIMO antenna is more acceptable for the design in portable device applications.

Joint Estimation of Carrier and Sampling Frequency Offsets Using OFDM WLAN Preamble

In this paper, the problem of joint estimation of carrier and sampling frequency offsets is considered, for IEEE 802.11ac-based OFDM wireless LAN systems, based on the guard interval and two long symbols (GI2L) in the preamble of a packet. The measurement model of the GI2L is developed, in the presence of both carrier and sampling frequency offsets. One method based on the GI2L is proposed and compared with some existing relevant methods based on long symbol/data symbols. An improved performance, measured by estimation error and bit error rate, is achieved by this method, at a similar computational load.

無線LANシステムのオフィス環境複数フロア間での伝搬損失および伝搬チャネルに関する検討(学生・若手発表および一般)

無線LANシステムのオフィス環境複数フロア間での伝搬損失および伝搬チャネルに関する検討(学生・若手発表および一般)

5-2 光無線LANによるATMバックボーンの構築

5-2 光無線LANによるATMバックボーンの構築

21-3 大規模数値シミュレーションに基づくデュアルバンド無線LAN システムの屋内伝搬チャネル推定(第21部門 無線・光伝送)

21-3 大規模数値シミュレーションに基づくデュアルバンド無線LAN システムの屋内伝搬チャネル推定(第21部門 無線・光伝送)

On the packet allocation of multi-band aggregation wireless networks

The use of heterogeneous networks with multiple radio access technologies (RATs) is a system concept that both academia and industry are studying. In such system, integrated use of available multiple RATs is essential to achieve beyond additive throughput and connectivity gains using multi-dimensional diversity. This paper considers an aggregation module called opportunistic multi-MAC aggregation (OMMA). It resides between the IP layer and the air interface protocol stacks, common to all RATs in the device. We present a theoretical framework for such system while considering a special case of multi-RAT systems, i.e., a multi-band wireless LAN (WLAN) system. An optimal packet distribution approach is derived which minimizes the average packet latency (the sum of queueing delay and serving delay) over multiple bands. It supports multiple user terminals with different QoS classes simultaneously. We further propose a packet scheduling algorithm, OMMA Leaky Bucket, which minimizes the packet end-to-end delay, i.e., the sum of average packet latency and average packet reordering delay. We also describe the system architecture of the proposed OMMA system, which is applicable for the general case of the multi-RAT devices. It includes functional description, discovery and association processes, and dynamic RAT update management. We finally present simulation results for a multi-band WLAN system. It shows the performance gains of the proposed OMMA Leaky Bucket scheme in comparison to other existing packet scheduling mechanisms.

遠隔操作型自律航行船開発に向けた画像伝送特性

Most of remotely controlled system for ship use a satellite communication system to send and receive operational commands. However, the satellite communication system has lots of problems such as slow traffic and delay. In order to attenuate these problems, a long-range Wireless LAN system has been applied instead of the satellite communication system. Experimental results to investigate characteristics of image transmission in wireless LAN at the sea are shown.

IEEE 802.11ah: A Long Range 802.11 WLAN at Sub 1 GHz

IEEE 802.11ah is an emerging Wireless LAN (WLAN) standard that defines a WLAN system operating at sub 1 GHz license-exempt bands. Thanks to the favorable propagation characteristics of the low frequency spectra, 802.11ah can provide much improved transmission range compared with the conventional 802.11 WLANs operating at 2.4 GHz and 5 GHz bands. 802.11ah can be used for various purposes including large scale sensor networks, extended range hotspot, and outdoor Wi-Fi for cellular traffic offloading, whereas the available bandwidth is relatively narrow. In this paper, we give a technical overview of 802.11ah Physical (PHY) layer and Medium Access Control (MAC) layer. For the 802.11ah PHY, which is designed based on the down-clocked operation of IEEE 802.11ac’s PHY layer, we describe its channelization and transmission modes. Besides, 802.11ah MAC layer has adopted some enhancements to fulfill the expected system requirements.These enhancements include the improvement of power saving features, support of large number of stations, efficient medium access mechanisms and throughput enhancements by greater compactness of various frame formats. Through the numerical analysis, we evaluate the transmission range for indoor and outdoor environments and the theoretical throughput with newly defined channel access mechanisms.

Parasitic effect compensation of defected ground structure and its application to design of bandpass filter

This study demonstrates the parasitic effect observed in the passband of a bandpass filter (BPF) using a defected ground structure (DGS). This parasitic effect has been compensated by employing step discontinuity in the microstrip feed line. By implementing this technique, the performance of a pseudocombline BPF of 5 GHz operating frequency and a fractional bandwidth of around 15% together with a DGS cell is improved. The filter provides less than −1 dB insertion loss in the operating frequency and a stop band attenuation of about −20 dB on average. When the final BPF structure is simulated, fabricated, and measured, good agreement is observed between the simulated and measured results. The BPF proposed is applicable in the wireless LAN and RADAR systems.