WLAN Coverage Research Articles

Preliminary study: Readiness of WLAN Infrastructure at Malaysian Higher Education Institutes to support Smart Campus Initiative

Smart campus initiative enables higher education to enhance services, decision-making, and campus sustainability. The initiatives are being actively implemented globally by higher education, including in Malaysia. The recent COVID-19 pandemic has underscored the need for the education sector to explore a digital revolution. The adaptation of digital technologies has improved many aspects, including the teaching and learning experiences and administration tasks, which results in more efficient task handling. This study investigates the readiness of the WLAN infrastructure at Malaysian Public Higher Education Institutes (HEIs) in implementing smart campus initiatives and measures readiness based on the availability of WLAN Infrastructure, WLAN logical architecture and WLAN populated coverage area. This study administered a questionnaire to 19 respondents, all of whom are IT personnel from Malaysian public HEIs to gather preliminary data on the readiness of WLAN infrastructure at Malaysian Public HEI to support the adaptation of smart campus initiatives in their teaching and learning activities. This study is a preliminary study concerning the readiness of WLAN infrastructure at Malaysian Public HEI in adapting smart campus initiatives. The findings show that, even though WLAN service is available at all Malaysian Public HEI, it is essential to enhance the adopted logical architecture and WLAN coverage to prepare HEI to become smart campuses. The findings of this study can provide the fundamental guidelines for the Ministry of Higher Education in determining the baseline of WLAN infrastructure required by Malaysian HEI to support smart campus initiatives.

Design and characteristic analysis of uniplanar multiband frequency selective surface for GSM, LTE, WLAN, ISM, WiMAX and X‐band applications

AbstractThe uniplanar compact, affordable, and unique slot‐based multiband frequency selective surface (FSS) of periodic cell size 0.14λc × 0.14λc (λc is wavelength at the initial stopband resonance) is presented in this article. The quadband FSS is analyzed using full‐wave simulation, circuit simulation (ECM), and experimental measurement where good agreement is attained. The FSS offers polarization independence with steady responses for all angular variations in the TE plane and up to 45° in the TM plane. The FSS offers dual stopbands at 2.75–4.15 and 9.45–12.48 GHz and dual passbands at 0.001–0.8 and 4.74–5.6 GHz that includes spectrum coverage of GSM, LTE, WLAN, ISM, WiMAX, and most part of X‐band communication.

Fabrication and optimization of bi-quad antenna and energy-efficient balanced RF power amplifier for 5G-LTE multi-carrier applications

Wireless technology is presently one of the most actively researched fields of digital communication systems. Wireless communication technologies are insufficient without an understanding of antenna design and operation. A wide range of radio frequency equipment, including microwave antennas, microwave ovens, cordless telephones, and medical devices, utilize the 2.4 GHz band. In this article, a parabolic mesh dish was used to build and improve a bi-quad antenna with a central working frequency of 2.445 GHz. The bi-quad antenna was put in a parabolic mesh dish to optimize wave propagation. The findings show that the antenna obtained a signal strength range of 70% to 80%, increasing the directivity of WLAN coverage. The bi-quad antenna feed was placed in the center of a mesh dish, which assists in focusing radio waves onto the antenna. The bi-quad antenna outperformed the omnidirectional antenna, which had a signal strength of 56%. The results of each antenna test were separately simulated in MATLAB. The combined impact of bi-quad and parabolic was then duplicated using mathematical models, resulting in a unique waveform propagation pattern known as para-quad, which improved performance. A balanced RF power amplifier was conceived and built in this study. A 2.620 - 2.690GHz frequency range on a large signal Si-LDMOS transistor model achieves 53% PAE, 41dBm power output, and 14 dB gain at the P1dB saturation point.

A High-Gain Microstrip Magnetic Dipole Antenna Utilizing Slot-Loaded High-Order Mode for WLAN Applications

A novel microstrip magnetic dipole (MMD) antenna is proposed to produce a high broadside gain utilizing slot-loaded high-order mode. Conventionally, MMD antennas yield patch currents in opposite directions when resonating in high-order modes. Radiations of these currents are out of phase and neutralize in the broadside direction, resulting in a low broadside gain. This work presents a method to reverse the out-of-phase currents by loading slots. An in-depth analysis is conducted to show the mechanism and effect of the slots. The proposed method is applied to a high-gain MMD antenna design for further gain enhancement. The improved antenna produces a large impedance bandwidth of 17.8% (5.1–6.1 GHz). A maximum broadside gain of 14.8 dBi is achieved within this bandwidth. The proposed antenna is promising for extending signal coverage of WLAN 5.5 GHz applications.

Distributed LoRa based CO2 monitoring network – A standalone open source system for contagion prevention by controlled ventilation

In the face of a global pandemic, such as that caused by the SARS-CoV-2 virus, the prevention of new infections is essential to stop the spread and ultimately return to normality. In addition to wearing masks and maintaining safe distances, regular ventilation in enclosed spaces where several people are gathered has proven to be an effective protective measure as advised by the World Health Organization. Additionally, as has been shown in a recent study of other airborne viruses, there is a strong correlation between the CO2level and aerosol content in a confined space under the assumption humans are the only CO2source. This can be exploited by means of a low-cost infrared CO2sensor to indirectly monitor the aerosol content and to provide targeted ventilation if predefined thresholds are exceeded. The distributed CO2monitoring network presented in this paper extends that idea and provides an inexpensive, comprehensive and modular monitoring network based on readily available components and 3D printing. By using a long-range communication link (LoRa) to centrally collect the real-time CO2concentration in a multitude of rooms, this network is particularly suitable for larger building complexes such as kindergartens, schools and universities without requiring partial or even full WLAN coverage.

Flexible Wearable Composite Antennas for Global Wireless Communication Systems.

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.

Offshore telemedicine emergency service: a 1-year experience

AimOffshore wind energy is a fast growing market. Accordingly, a correspondingly large number of employees are working at the wind farms. Owing to the harsh operating conditions, accidents and medical emergencies occur there. The care of these patients poses special challenges. The aim of the investigation was to determine whether telemedical emergency care is technically possible on the North Sea, far away from any medical care.Subject and methodsWe were able to establish a raw data supported telemedical integration with a rescue service monitor for transmission of ECG, blood pressure, saturation and other vital parameters to a telemedicine centre. As a first step, a satellite connection was set up on a supply ship for the transmission, which was then made available for data transfer via WLAN.ResultsIn this project, we were able to show in tests as well as in actual patient care that telemedical support of rescue service personnel on site using raw data transmission is also possible offshore on a supply ship. In this project, defined areas with WLAN coverage were necessary in which the transmission worked in 100% of cases.ConclusionThe care of emergencies in the area of offshore wind farms is an increasing problem, which can be sensibly treated with telemedical support. Technical possibilities can also be created on site in the North Sea. The further expansion of a communication network, for example, with LTE or 5G, is necessary to enable telemedical care independent of supply ships.

Proposed APs Distribution Optimization Algorithm: Indoor Coverage Solution

Recently, Wireless systems for indoor environments have become very important and popular. With increasing the need for mobile devices like laptops, tabs and smartphones, the optimization of WLAN coverage became very necessary to provide efficient communication with less cost. This optimization is verified by decreasing number of WiFi Access Point coverage. A multi objectives algorithm is proposed in this paper to optimize WiFi coverage in indoor environment using MatLab software. The proposed algorithm employs (BPSO) to determine the optimal number and locations for WiFi APs distribution based on predefined received power thresholds value. it has been found that the proposed algorithm is flexible using weighted multi-fitness functions. In addition, conducting site survey in real environment verifies the reliability of the proposed algorithm. Applying APD-CS algorithm in the adopted real environment increase the coverage by 64.6% and the average received power 7 dBm at Pth equal to-55 dBm.

WLAN Bandwidth-Based Handoff from WLAN to Cellular Network Assisted by Ad hoc Relaying

Loosely coupled interworking WLAN/cellular system has attracted a lot of attention recently, since the WLAN bandwidth is not restricted by the cellular network. In this kind of systems, a handoff from the WLAN to the cellular network is considered as a new call and therefore incurs a significant delay. Hence, the mobile station (MS) has to accomplish the handoff ahead of losing the WLAN coverage. In many cases the MS enters a region with a low bit rate before completing the handoff. This paper tries to aid the handoff by allocating the requested WLAN bandwidth to maintain the MS link with the serving access point as much as possible. In the case of WLAN bandwidth shortage, the handoff is assisted by using MS’s as ad hoc relay stations (RS’s) to extend the WLAN coverage. In a low-density WLAN, usually the handoff is accomplished by the aid of WLAN bandwidth. In contrast, in a high-density WLAN, the chance of finding a proper RS is high while the amount of available WLAN bandwidth is low. As a result, generally the handoff is accomplished by the assistance of potential RS’s. Both analytical and simulation results are provided to validate the effectiveness of the proposed method in terms of decreasing the call dropping probability.

Vertical Handoff from WLAN to Cellular Network Based on Relay Environment

Seamless handoff in loosely coupled WLAN/cellular systems is still a challenging issue. Since the cellular network overlaps the WLAN during a handoff from a cellular network to a WLAN, this type of handoff is less complicated. Thus, all the attempts go toward the handoff from the WLAN to the cellular network. In the cellular network, this handoff is considered as a new call. Therefore, it has a significant delay which makes it inappropriate for the real-time services. The worst case occurs when a mobile station (MS) exits a building surrounding the WLAN. In such a case, there might not be enough time for the handoff to be completed due to the abrupt loss of the received signal strength indication. In this paper, the proposed solution uses MSs as relay stations (RSs) and the existing frequency channels dedicated to the RSs to provide the required WLAN coverage during the handoff process. The suggested solution is analyzed using a simple proposed analytical model. Both the analytic and simulation results confirm that the suggested method improves the handoff dropping probability.

WLAN bandwidth support for relay-based upward handover in WLAN/cellular systems

Handover from WLAN to a cellular network in loosely coupled WLAN/Cellular systems is considered as a new call and therefore is not given any priority in the cellular network. Hence, it induces a remarkable delay that makes loosely coupled WLAN/Cellular systems inappropriate for online services. Due to this fact, during a handover from a WLAN to a cellular network, a mobile station (MS) may be trapped in a low bit rate region before completing the handover. This paper suggests using relay stations (RS's) during a handover to extend WLAN coverage until the handover is completed. When RS’s are not available, especially in sparse hotspots, allocating a large amount of the WLAN bandwidth to the MS can assist the handover process. In contrast, in a dense hotspot, the probability of finding an appropriate RS is high. Thus, the handover could be completed by using the potential RS's inside the WLAN coverage. It is confirmed, by analytical modeling and simulation, that the proposed method can reduce the call dropping probability and improve the handover performance.

Adaptive informant factor-based optimised channel allocation in large-scale mesh networks

The demand for expanded WLAN coverage is increasing more than ever, due to increasing number of computing and communications devices which are equipped with an integrated IEEE 802.11 WLAN interface - including smart-phones, notebook PCs and multimedia components. As wireless mesh networks (WMN) collect and relay the traffic generated by many clients, there have been several research efforts to improve the network capacity. One of the strategies is through the coordinated use of multiple channels and multiple radios. Thus, the channel assignment to a mesh node becomes an important research issue. Therefore, in this paper AIF-based optimised channel allocation is proposed, which acquires the information of channel of a network and then processes it to optimise the RF channel allocation. The proposed AIF-OCA functions for each period when some interference is detected via AIF. The arrangement of Relay Nodes (RN) and RF channels with IEEE 802.11s/u standard is considered in the proposed model. To validate the performance of the proposed model, it is compared with several existing techniques in WMN environment.

A Study on Minimization of 3G/4G Handover Failure

One of the better thought-provoking features of Fourth Generation networks is their assimilation with Third Generation networks. It supports seamless End to-End services. At present extensively deployed Third Generation and Fourth Generation networks provide enabling interoperability. The particular mechanisms have Inter RAT idle mode reselection. Inter RAT dedicated mode reselection is used for Packet Switching services. The WLAN coverage on one hand contribute an further coverage in the low signal strength sector. We achieved the channel scanning with in the WLAN coverage area. To decrease the handover failure by reason of scanning delay.

Geometrical Characterization of Offloading through Wireless LANs

The offloading of cellular traffic through WLAN APs (wireless local area network access points) distributed in a homogeneous Poisson process (HPP) is theoretically evaluated. The probability $P_w$ that a user can use WLAN and the expected number of vertical handovers $N_h$ are evaluated as the basic performance metrics of WLAN AP coverage. Explicit formulas are derived for the metrics, and the fundamental relationships between the metrics and many parameters such as the shape of each WLAN coverage region $D_1,D_2,\ldots$ are described. These metrics depend on the size and perimeter length of $D_i$ but do not depend on their other shape parameters for a convex $D_i$ . In addition, it is proven that a disk-shaped $D_i$ minimizes $N_h$ for a fixed WLAN coverage size and that $P_w$ is often insensitive to the perimeter length of $D_i$ . It is also proven that the $P_w$ of a user at a random location is equal to that moving along a random straight line or a random bounded curve. One hundred empirical location data sets of WLAN APs in Japan, Korea, and the US were used to confirm the theoretical results. Although these locations do not follow an HPP, many theoretical results are shown to be valid. For example, $N_h$ is minimized by a disk-shaped $D_i$ . Simultaneously, we find that $P_w$ slightly increases when a slender $D_i$ is used for highly clustered AP locations.

PERFORMANSI WLAN KANTOR PUSAT PEMERINTAH KABUPATEN BADUNFG

WLAN has been implemented widely, including in public area and government office. Badung Regency office has got benefit from the technology in applying its e- government services. However the WLAN performance in term of its QoS has not been evaluated after its installation. Then its delay, packet loss, throughput, and jitter were measured using Ekahau Heatmapper, Axence Nettols, Wi-Fi Analyzer, and Ubiquiti Unifi. The WLAN coverage area was calculated and analyzed. Generally, the performance is good. However there are areas in all 12 buildings in the offices that are needed more access points.

Performansi WLAN Kantor Pusat Pemerintahan Kabupaten Badung

WLAN has been implemented widely, including in public area and government office. Badung Regency office has got benefit from the technology in applying its e- government services. However the WLAN performance in term of its QoS has not been evaluated after its installation. Then its delay, packet loss, throughput, and jitter were measured using Ekahau Heatmapper, Axence Nettols, Wi-Fi Analyzer, and Ubiquiti Unifi. The WLAN coverage area was calculated and analyzed. Generally, the performance is good. However there are areas in all 12 buildings in the offices that are needed more access points.

PEOPLE’S PPRESENCE EFFECT ON WLAN-BASED IPS’ ACCURACY

In order to enable Location Based Service (LBS) closed environment, many technologies have been investigated to replace the Global Positioning System (GPS) in the localization process in indoor environments. WLAN is considered as the most suitable and powerful technology for Indoor Positioning System (IPS) due to its widespread coverage and low cost. Although WLAN Received Signal Strength Indicator (RSS) fingerprinting can be considered as the most accurate IPS method, this accuracy can be weakened due to WLAN RSS fluctuation. WLAN RSS fluctuates due to the multipath being influenced by obstacles presence. People presence under WLAN coverage can be considered as one of the main obstacles which can affect the WLAN-IPS accuracy. This research presents experimental results demonstrating that people’s presence between access point (AP) and mobile device (MD) reduces the received signal strength by -2dBm to -5dBm. This reduction in RSS can lead to distance error greater than or equal to 2m. Hence, any accurate IPS must consider the presence of people in the indoor environment.

Theoretical aspects of designing a wireless communication network with broadband access to the main network infrastructure

The problem of designing wireless communication networks when the use of traditional cable technologies is inappropriate for data exchange between the computer networks is discussed. A link between network segments built with Wi-Fi on the basis of broadband-access WiMAX is proposed. Features of theoretical calculation of Wi-Fi networks with broadband access in relation to the main network infrastructure are considered. An expanded algorithm for designing Wi-Fi that increases the precision of computation of the coverage area of Wi-Fi access points and the geometry of wireless transport links on the basis of radio-signal propagation in planar and spatial projections (2D and 3D). An algorithm is given for determining the geometry of the base station and WiMAX subscriber units with the resulting Fresnel zones being identified. The proposed algorithm is tested by an example of designing a communication network for a group of interconnected Wi-Fi access points providing extended WLAN coverage for mobile devices in an enclosed indoor large and elevated area. The obtained results show that use of the algorithms that have been developed for designing wireless networks of the given class is effective.

Smart WLAN Discovery for Power Saving of Dual‐Mode Terminals

Dual‐mode terminals (DMTs) equipped with cellular and WLAN interfaces have become popular in recent years. Users of DMTs can enjoy high‐speed WLAN Internet access and wide area Internet access to cellular networks. However, a DMT may consume power inefficiently when discovering a WLAN with inherently limited service coverage. In this letter, we propose to use smart WLAN discovery (SWD) to minimize the power consumption required for WLAN discovery. To minimize the power consumption of a DMT, an SWD DMT activates its WLAN interface only when the DMT transfers data within the WLAN coverage area. The simulation results of SWD show an improved power‐saving performance compared to previous WLAN discovery schemes.

Performance Analysis of Ubiquitous Wireless Connectivity in a 3G/IEEE 802. 11 Integrated Network

UMTS networks promise to offer always on, ubiquitous connectivity with relatively low data rates for moderate to high mobility users in macro cell environments. On the other hand, IEEE 802.11 (WLAN) offers much higher data rates, comparable to 3G and other wireless local area networks, to users with low mobility characteristics in smaller cell environments. Where UMTS/WLAN networks overlap, a dual-mode UMTS/WLAN terminal could access high bandwidth data services where WLAN coverage is offered and use UMTS services elsewhere. This leads to fundamental questions on how UMTS and WLAN can be integrated, It were build two different scenarios, one for loose coupling scheme and the other one for open coupling scheme. In loose coupling scheme both billing and authentication is common for UMTS and WLAN networks while in case of open coupling scheme only billing is common for WLAN and UMTS where as they use there own separate authentication servers. The OPNET simulated results reveal that the loose coupling architecture performance is better than the open coupling architecture for all the applied applications and measurement parameters during the Mobility between WLAN and UMTS.