Search Results (341)

With the rapid development of wireless communication, Wireless Local Area Networks (WLANs) are widely deployed in high-density environments. Ensuring fast handovers and optimal AP selection during device roaming is critical for maintaining network throughput and user experience. However, frequent mobility, high access density, and dynamic channel fluctuations complicate throughput prediction. To address this, we propose a method combining the Snow-Melting Optimizer (SMO) with decision tree regression models to optimize feature selection and model transmission opportunities (TXOP) and AP throughput. Experimental results show that the Extreme Gradient Boosting (XGBoost) model performs best, achieving high prediction accuracy for TXOP (MSE = 1.3746, R² = 0.9842) and AP throughput (MAE = 2.5071, R² = 0.9896). This approach effectively captures the nonlinear relationships between throughput and network factors in dense WLAN scenarios, demonstrating its potential for real-world applications. Full article

We propose a multiple-input multiple-output (MIMO) multi-band antenna for the WiFi-6E band. The planar size of the proposed antenna is 40 × 7.6 mm², and it is built on a FR4 substrate with a thickness of 0.8 mm. By utilizing a 3 × 3.8 mm² L-shaped parasitic element, additional resonant modes are introduced through coupling and resonance. The operating frequency bands are WLAN 2.4 GHz (2.4–2.8 GHz) and Wi-Fi 6E (5.06–7.13 GHz). The average antenna gain is 4.2 dBi, with an envelope correlation coefficient (ECC) less than 0.020 and a radiation efficiency between 70% and 92%. Full article

In this paper, a compact multi-split-ring resonator-based antenna is presented for wireless applications. The proposed antenna integrates multiple resonators to achieve multiband operation, where each resonator corresponds to a specific frequency band. A theoretical analysis is conducted to model the equivalent circuit of the proposed antenna, followed by an analytical study to calculate the resonant frequency of each resonator. By integrating these resonators, the proposed antenna achieves a compact size of 23 × 24 × 1.6 mm³ (0.19 × 0.2 × 0.01λ³), resulting in a size reduction of 81.6% compared to a conventional patch antenna, while maintaining gain, improving bandwidth, and providing excellent impedance matching. The proposed antenna covers the 2.4–2.8 GHz (14.55%), 3.25–3.75 GHz (14.28%) and 4.5–7.84 GHz (54.13%) frequency bands, providing acceptable gains of 1.5 dBi, 2 dBi and 3.2 dBi, respectively. The antenna was designed with CST, its performance was verified with HFSS simulations and it was validated with an equivalent circuit in ADS. Finally, the antenna was fabricated to confirm the accuracy and reliability of the simulation results, and it was found that the measurements agreed well with the simulations. This multiband functionality, combined with a compact form factor and simple feed line, makes the antenna cost-effective, easy to manufacture and suitable for various wireless communication applications, including 5G sub-6 GHz mid-band (2.5/3.5/5/5 GHz), RFID (2.45/5.8 GHz), WiMAX (2.4/3.5/5.8 GHz), Wi-Fi 5/6/6E (2.4/5/6 GHz) and WLAN (5.2/5.8 GHz). Full article

With the rapid development of Wi-Fi 6/6E and dual-band wireless systems, there is an increasing demand for compact antennas with balanced high-gain performance across both 2.4 GHz and 5 GHz bands. However, most existing dual-band metasurface antennas face challenges in uneven gain distribution between lower/higher-frequency bands and structural miniaturization. This paper proposes a high-gain dual-band metasurface antenna based on an artificial magnetic conductor (AMC) array, which has a significant advantage in miniaturization and improving antenna performance. Two types of dual-band AMC structures are applied to design the metasurface antenna. The optimal antenna with dual-slot AMC array operates in the 2.42–2.48 GHz and 5.16–5.53 GHz frequency bands, with a 25% size reduction compared to the reference dual-band U-slot antenna. Meanwhile, high gains of 7.65 dBi and 8 dBi are achieved at 2.4 GHz and 5 GHz frequency bands, respectively. Experimental results verify stable radiation gains across the operation bands, where the total efficiency remains above 90%, agreeing well with the simulation results. This research provides an effective strategy for high-gain and dual-band metasurface antennas, offering a promising solution for integrated modern wireless systems such as Wi-Fi 6, Bluetooth, and MIMO technology. Full article

Wireless Local Area Networks (WLANs), particularly Wi-Fi, serve as the backbone of modern connectivity, supporting billions of devices globally and forming a critical component in Internet of Things (IoT) ecosystems. However, the increasing ubiquity of WLANs also presents an expanding attack surface for adversaries—especially Advanced Persistent Threats (APTs), which operate with high levels of sophistication, resources, and long-term strategic objectives. This paper provides a holistic security analysis of WLANs under the lens of APT threat models, categorizing APT actors by capability tiers and examining their ability to compromise WLANs through logical attack surfaces. The study identifies and explores three primary attack surfaces: Radio Access Control interfaces, compromised insider nodes, and ISP gateway-level exposures. A series of empirical experiments—ranging from traffic analysis of ISP-controlled routers to offline password attack modeling—evaluate the current resilience of WLANs and highlight specific vulnerabilities such as credential reuse, firmware-based leakage, and protocol downgrade attacks. Furthermore, the paper demonstrates how APT resources significantly accelerate attacks through formal models of computational scaling. It also incorporates threat modeling frameworks, including STRIDE and MITRE ATT&CK, to contextualize risks and map adversary tactics. Based on these insights, this paper offers practical recommendations for enhancing WLAN resilience through improved authentication mechanisms, network segmentation, AI-based anomaly detection, and open firmware adoption. The findings underscore that while current WLAN implementations offer basic protections, they remain highly susceptible to well-resourced adversaries, necessitating a shift toward more robust, context-aware security architectures. Full article

This paper presents the design analysis of a low-power wideband single-ended CMOS low-noise amplifier (LNA). The proposed topology is based on a modified current- reuse circuit, in which two-stage common-source (CS) amplifiers consume the same DC current and are isolated from each other by large MIMCAPs, which results in good performance with low power consumption. The proposed circuit achieves a bandwidth of 2.5 GHz, suitable for several wireless communication standards such as GSM, WLAN, and Bluetooth. In the first stage, a current-reuse circuit with shunt feedback is used to satisfy input impedance matching and signal amplification with minimal noise injection. A common source (CS) with a source follower circuit forms the second stage to improve the noise figure (NF), harmonic distortion, and output impedance matching. The proposed LNA is designed in 65 nm CMOS technology and covers a frequency range of 0.17–2.68 GHz. The proposed LNA achieves a maximum gain of 17.24 dB, a minimum NF of 2.67 dB, a maximum IIP3 of −14.9 dBm, and input and output return losses of less than −10 dB. The power consumption of the proposed LNA is 3.52 mW from a 1 V power supply, and the core area is 0.3 mm². Full article

The increasing deployment of IEEE 802.11ax (Wi-Fi 6) networks necessitates an accurate assessment of radiofrequency electromagnetic field (RF-EMF) exposure under realistic usage scenarios. This study investigates the duty cycle (DC) and corresponding exposure levels of Wi-Fi 6 in controlled laboratory conditions, focusing on bandwidth variations, multi-user scenarios, and application types. DC measurements reveal significant variability across internet services, with FTP upload exhibiting the highest mean DC (94.3%) under 20 MHz bandwidth, while YouTube 4K video streaming showed bursts with a maximum DC of 89.2%. Under poor radio conditions, DC increased by up to 5× for certain applications, emphasizing the influence of degraded signal-to-noise ratio (SNR) on retransmissions and modulation. Weighted exposure results indicate a reduction in average electric-field strength by up to 10× when incorporating DC, with maximum weighted exposure at 4.2 V/m (6.9% of ICNIRP limits) during multi-user scenarios. These findings highlight the critical role of realistic DC assessments in refining exposure evaluations, ensuring regulatory compliance, and advancing the understanding of Wi-Fi 6’s EMF exposure implications. Full article

This paper presents a simple design of a two-element antenna with circularly polarized (CP) reconfigurability for multiple-input multiple-output wireless local-area network (WLAN) applications. A MIMO element consists of a reconfigurable feeding network, a CP source, and a 2 × 2 unit-cell metasurface (MS). By controlling the ON/OFF state of PIN diodes, the proposed MIMO system can operate in either right-hand CP (RHCP) or left-hand CP (LHCP) for all ports, or either RHCP or LHCP for each port. For all operating modes, the proposed antenna exhibits good performance with a matching performance of less than –10 dB, an axial ratio of lower than 3 dB, as well as an inter-port isolation of better than 24 dB at 2.45 GHz. Additionally, the MIMO diversity performance is also satisfied by the proposed antenna. Compared to related works, the proposed antenna has advantages of high gain and compact size, as well as a simple switching mechanism with a small number of PIN diodes. Full article

This paper presents a novel multi-layer, dual-band antenna array designed for WLAN and X-band applications, incorporating several innovative features. The design employs a pentagon-shaped radiating element with parasitic strips to enable dual-band operation. A dual-transformed feed network with chamfered feed strip corners minimizes radiation distortion and cross-polarization while introducing orthogonal phase shifts to achieve circular polarization (CP) at the X-band. A Fabry–Pérot structure, strategically placed above the array, enhances gain in the WLAN band. The antenna demonstrates an impedance bandwidth of 1.8 GHz (S₁₁ < −10 dB) at the WLAN band, with 36% fractional bandwidth, and 4.3 GHz at the X-band, with 43% fractional bandwidth. Measured peak gains are 7 dBi for the WLAN band and 6.8 dBi for the X-band, with favourable S₁₁ levels, omni-directional radiation patterns, and consistent gain across both bands. Circular polarization is achieved within 8.5–10.4 GHz. Experimental results confirm the array’s significant advancements in multi-band performance, making it highly suitable for diverse wireless communication applications. Full article

The Enhanced 911 (E911) mandate of the Federal Communications Commission (FCC) drives the evolution of indoor three-dimensional (3D) location/positioning services for emergency calls. Many indoor localization systems exploit location-dependent wireless signaling signatures, often called fingerprints, and machine learning techniques for position estimation. In particular, received signal strength indicators (RSSIs) and Channel State Information (CSI) in Wireless Local Area Networks (WLANs or Wi-Fi) have gained popularity and have been addressed in the literature. While RSSI signatures are easy to collect, the fluctuation of wireless signals resulting from environmental uncertainties leads to considerable variations in RSSIs, which poses a challenge to accurate localization on a single floor, not to mention multi-floor or even three-dimensional (3D) indoor localization. Considering recent E911 mandate attention to vertical location accuracy, this study aimed to investigate CSI from Wi-Fi signals to produce baseline Z-axis location data, which has not been thoroughly addressed. To that end, we utilized CSI measurements and two representative machine learning methods, an artificial neural network (ANN) and convolutional neural network (CNN), to estimate both 3D and vertical-axis positioning feasibility to achieve E911 accuracy compliance. Full article

This paper presents a hybrid dielectric resonator antenna (HDRA) for circularly polarized (CP) radiation at 5 GHz, designed for WLAN applications. The antenna features a single probe feed that excites a combination of a circular ring patch and a cylindrical dielectric resonator (DR) element, achieving stable gain across a wide bandwidth. The parametric analysis and vector E-field distribution of the proposed antenna presents the optimization, and it is evidence of CP radiation, respectively. The hybrid DRA has a reflection loss (RL) bandwidth of 485 MHz, from 4740 to 5225 MHz, and an axial ratio (AR) bandwidth of 150 MHz, ranging from 4950 to 5100 MHz. It achieves a peak gain of 7.03 dBic at 5 GHz, making it suitable for missile tracking, data link communications, and IEEE 802.11n WLAN systems. Measurements of a prototype in an anechoic chamber show a close match with simulation results. Full article

In this paper, based on bionics, a flexible multi-band antenna is designed to mimic the structure of a spider’s web, which supports various communication standards such as 4G, 5G, and GPS. The antenna lays out multiple loop branches in a limited space to achieve wideband operations from 1.31 GHz to 2 GHz (42.4%), from 3.4 GHz to 4 GHz (16.2%), and from 5.1 GHz to 5.78 GHz (12.5%). The antenna selects 40 × 50 × 0.1 mm³ polyimide as the dielectric substrate and trapezoidal coplanar waveguide feed. A simulation and experimental analyses demonstrate that the antenna exhibits consistent performance when subjected to different bending scenarios. The design scheme utilizing a flexible dielectric substrate streamlines the integration process, offering a promising avenue for deployment in smart wireless devices. The results of the consistent tests and simulations demonstrate that the device meets the requisite standards for wireless communication. Full article

This paper presents a novel double-sided structure multi-band antenna that cleverly combines a Koch snowflake structure with a hexagonal fractal structure; the front of the antenna features a right semicircle minus a half-order Koch snowflake structure, while the back of the antenna showcases a left semicircle minus half of a hexagonal fractal snowflake structure, which are combined together to form a complete circle. The antenna can cover common communication bands such as fourth to fifth generation (5G) commercial bands, ISM, WLAN, and Bluetooth. The structure of the radiator portion of the antenna is designed by iteratively scaling a basic arc shape multiple times based on a certain scale factor, and after simulation and comparison, three iterations can achieve the best antenna performance, and the antenna uses a microstrip line transmission to broaden the antenna bandwidth. The antenna covers three effective frequency bands: 2.38–2.90 GHz (20.3%), 3.35–3.85 GHz (14.1%), and 5.06–5.80 GHz (13.5%). The antenna dielectric sheet is made of RF-35 from Taconic, which has the advantages of high strength, complete surface inertness, and a long service life, with a dielectric constant of 3.5 and actual dimensions of 50 mm × 54 mm × 0.76 mm. The antenna is fractal-iterated in small dimensions, and the approximation of the frequency bands is accomplished by comparing the ratios of each iteration with the current vector map. The antenna was simulated by HFSS software (Version 21). and measured in an electromagnetic anechoic chamber, and the test results were consistent with the simulation results. Full article

The proliferation of IoT using heterogeneous wireless technologies within the unlicensed spectrum has intensified cross-technology interference (CTI) in wireless local area networks (WLANs). As WLANs increasingly adopt time-triggered transmission methods to support real-time services, this interference affects throughput, packet loss, and latency. This paper presents a CTI-aware rate adaptation framework designed to mitigate interference in WLANs without direct coordination with heterogeneous wireless devices. The framework includes a CTI identification model and CTI-aware rate selection algorithms. Leveraging short-time Fourier transform, the identification model captures the time–frequency–power characteristics of CTI signals, enabling the estimation of the average power of various heterogeneous wireless technologies employed by interfering devices. The rate selection algorithms predict CTI occurrence times and adjust the transmission rate accordingly, enhancing the performance of existing explicit and implicit interference mitigation methods. Experimental results demonstrated that the lightweight CTI identification model accurately estimated the average power of each type with an error margin of ±1.414 dBm, achieving this in under 1 ms on the target hardware. Additionally, applying the proposed framework to explicit interference mitigation enhanced goodput by 20.67%, reduced packet error rate by 2.38%, and decreased the probability of packets exceeding 1 ms latency by 0.932% compared to conventional methods. Full article

To address the severe spectrum shortage in mobile networks, the 3rd Generation Partnership Project (3GPP) standardized Long Term Evolution (LTE)-License Assisted Access (LAA) technology. The LTE-LAA system ensures efficient coexistence with other existing unlicensed systems by incorporating listen-before-talk functionality and conducting random backoff operations similar to those in the IEEE 802.11 distributed coordination function. In this paper, we propose an analytical model to calculate the throughput of each system in a scenario where a single LTE-LAA system shares an unlicensed channel with multiple wireless local area network (WLAN) systems. The LTE-LAA system is utilized for supplementary downlink transmission from the LTE-LAA eNodeB (eNB) to LTE-LAA devices. Our proposed analytical model uses a Markov chain to represent the random backoff operations of the LTE-LAA eNB and WLAN nodes under non-saturated traffic conditions and to calculate the impact of the clear channel assessment (CCA) performed by the LTE-LAA eNB. Through numerical results, we demonstrate how the throughput of both the LTE-LAA and WLAN systems is determined by the contention window size and CCA threshold of the LTE-LAA eNB. Full article