Local Area Network Applications Research Articles

A 170 MHz to 330 MHz Wideband 90 nm CMOS RC–CR Phase Shifter with Integrated On-Line Amplitude Locked Loop Calibration for Hartley Image Rejection Transceiver

A 160 MHz bandwidth 90° active RC–CR phase shifter with integrated on-line amplitude locked loop (ALL) calibration targeted to 802.11ac 5 GHz wireless local area network (WLAN) applications is presented in this paper. The quadrature phase shifter is a key component for transceivers employing the Hartley image rejection architecture. The passive RC–CR phase shifter generates the required two quadrature outputs with an accurate 90° phase shift over the required bandwidth but lack the required accuracy in amplitude matching. A 90 nm CMOS microelectronic implementation of an RC–CR phase shifter is proposed with active resistors that are adjusted by an integrated on-line ALL calibration system to maintain matching amplitudes of the quadrature outputs over the required bandwidth. The on-line ALL calibration system employs peak detectors, comparators, digital logic control, and charge pump to incrementally adjust the active resistors while converging to matched amplitudes similar to the operation of phase-locked loop with a phase-frequency detector and charge pump. The resulting 90 nm implementation supports − 40db to − 70db image rejection ratios (IMMRs) over the IF 170 MHz to 330 MHz bandwidth. The 90 nm CMOS implementation is fully functional considering process variations based on 200 Monte Carlo simulations.

An Improved Comparator Based on Current Reuse and a New Frequency Compensation Technique used in an OTA for Pipeline ADCs

In this paper, a comparator and an operational amplifier considered as essential components, constituting a 10-bit 50-MHz pipeline Analog-to-Digital Converter for Wireless Local Area Network (WLAN) applications, are described and designed. All post-layout and Monte-Carlo simulations, using a 0.35[Formula: see text][Formula: see text]m CMOS AMS process technology with [Formula: see text][Formula: see text]V supply voltage and an input common-mode range of [Formula: see text][Formula: see text]V, are achieved. An improved clocked comparator with a dynamic latch, based on a switched capacitor network, using the current reuse technique for slew rate enhancement and positive feedback for offset voltage compensation, is presented. The operational amplifier, consisting of a fully differential folded cascode operational transconductance amplifier, providing high-gain and good stability, is exhibited. A new frequency compensation technique, based on active resistors, is used to improve amplifier phase-margin. The Monte-Carlo performance results of the designed clocked comparator provide an offset voltage of [Formula: see text][Formula: see text]mV with [Formula: see text][Formula: see text]mV 3[Formula: see text] deviation, a slew rate of [Formula: see text]V/ns with [Formula: see text]V/ns 3[Formula: see text] deviation, and a propagation delay of [Formula: see text][Formula: see text]ns with [Formula: see text][Formula: see text]ns 3[Formula: see text] deviation. Monte-Carlo performance results of the designed operational amplifier provide a phase-margin of [Formula: see text], and a high-gain of [Formula: see text]dB with [Formula: see text] and [Formula: see text]dB 3[Formula: see text], respectively, by using [Formula: see text] load capacitance.

Three‐port circularly polarized MIMO antenna for WLAN application with pattern and polarization diversity

AbstractIn this article, a three‐port circularly polarized (CP) multiple‐input multiple‐output (MIMO) antenna for wireless local area network (WLAN) application with pattern and polarization diversity is proposed. The proposed MIMO antenna system comprises of a broadside CP antenna element with a T‐shaped slot and two endfire CP antenna elements. Good impedance bandwidth of 16.9% and 5.5% are achieved by the broadside CP antenna and endfire CP antenna, respectively, and their corresponding axial ratio (AR) bandwidth is 7% and 10.47%. The isolation between the different antenna elements is better than 20 dB, and the polarization purity for all CP antenna is more than 25 dB along with the maximum radiation.

A New Metasurface Structure for Bandwidth Improvement of Antenna Array

In this paper, the design of an antenna array with enhanced bandwidth is presented. The antenna array includes 16 elements (4 x 4) based on RT5880 with height of 1.575 mm, dielectric constant of 2.2 and loss tangent of 0.0009 and it is yielded at the central frequency of 5.8 GHz for Wireless Local Area Network (WLAN) applications. In addition, in order to enhance bandwidth for antenna, the paper proposes a new metasurface. The metasurface, which is a lattice of 3 x 3 cells, is printed on a substrate of FR4 (h = 1.6 mm, ɛr = 4.4, and tanδ = 0.02) and it acts as an artificial magnetic conductor reflector. The final prototype with an overall dimension of 123 x 120 x 3.315 mm3 was fabricated and measured. The antenna witnesses an impedance bandwidth of 5.1-7.5 GHz at -10 dB (41%) and a peak gain of 17.65 dBi for measurement. The simulation results are confirmed by measurement ones to verify the performance of the proposed antenna.

A Low Profile Dual-Band High Gain Directional Antenna for Anti-Interference WLAN Station Applications

This paper presents a low-profile dual-band antenna with directional radiation characteristics for wireless local area network (WLAN) applications. The proposed directional antenna is composed of a coupling microstrip line, two F-shaped strips, two rectangular strips, and a defected ground plane. The measured impedance bandwidth of the proposed antenna is 180 MHz (2.33–2.51 GHz) and 830 MHz (5.09–5.92 GHz), which can cover Institute of Electrical and Electronic Engineers (IEEE) 802.11 a/b/g frequency bands. The dual-band antenna exhibits a desirable directional radiation patterns in the vertical and horizontal planes with the peak gain of 6.55 dBi in the lower frequency band and 8.1 dBi in the higher frequency band. The measured antenna efficiency is 70% at 2.4 GHz and 84.5% at 5.5 GHz. The proposed dual-band WLAN station antenna is designed on a FR4 substrate with overall dimensions of 69 mm × 50 mm × 1.6 mm.

Compact omnidirectional dual‐band dipole antenna with reduced ground plane effect

AbstractIn this letter, a compact omnidirectional dual‐band antenna is designed for wireless local area network applications. The proposed antenna is printed on the two sides of an FR4 substrate that the total dimension is 12 × 46 × 0.5 mm3. A dipole antenna is used to cover the lower operating band (2.45 GHz), while a capacitances‐loaded patch generates a higher resonance (5.5 GHz). This antenna has a good impedance matching in the operation band, and the gain is 2.28 and 4.42 dBi in the lower and upper bands, respectively. To address the problem that the performance will drastically decline when the antenna is located on a ground, a quarter wavelength spiral line is employed to decrease the negative effect of the ground. Two proposed dipole antennas, placed on a horizontal ground as a MIMO antenna system, are analyzed with different configurations. The results reveal that the proposed method can effectively reduce the ground plane effect and improve the diversity performance, which has huge potential applications in MIMO system.

A Single-Layer Low-Profile Circularly Polarized Filtering Patch Antenna

A single-layer low-profile circularly polarized (CP) filtering patch antenna is investigated for wireless local area network (WLAN) applications. The CP antenna mainly consists of a feeding loop, four L-shaped radiating patches, and a square ground plane. To integrate the filtering function, four thin microstrip stubs and four shorting pins are introduced to the patches, and two U-shaped slots are etched in the feeding loop. These parasitic elements can realize the bandpass filtering function without requiring an external filter. In addition, these elements are skillfully added into the CP antenna, without increasing either the antenna footprint or profile. To verify the design, a prototype operating at 2.4 GHz WLAN band is fabricated and tested. The measured results show that the prototype has a low profile of 0.02λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , a passband bandwidth (|S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB and axial ratio (AR) <; 3 dB) of 4.1%, and a peak gain of 8.3 dBic. Moreover, the prototype also shows a sharp roll-off rate near the passband edge and a good out-of-band suppression level of more than 20 dB in the stopbands.

Concurrent Dual-Band Inverter-Based Low Noise Amplifier (LNA) for WLAN Applications

low noise amplifier (LNA); concurrent; dual-band; inverter-basedIn this paper, a two-stage concurrent dual-band low noise amplifier (DB-LNA) operating at 2.4/5.2-GHz is presented for Wireless Local Area Network (WLAN) applications. The current-reused structure using resistive shunt-shunt feedback is employed to reduce power dissipation and achieve a wide frequency band from DC to-5.5-GHz in the inverter-based LNA. The second inverter-based stage is employed to increase the gain and obtain a flat gain over the frequency band. An LC network is also inserted at the proposed circuit output to shape the dual-band frequency response. The proposed concurrent DB-LNA is designed by RF-TSMC 0.18-µm CMOS technology, which consumes 10.8 mW from a power supply of 1.5 V. The simulation results show that the proposed DB-LNA achieves a direct power gain (S 21 ) of 13.7/14.1 dB, a noise figure (NF) of 4.2/4.6 dB, and an input return loss (S 11 ) of −12.9/−14.6 dBm at the 2.4/5.2-GHz bands.

X-band CMOS VCO for 5 GHz Wireless LAN

The implementation of a low phase noise voltage controlled oscillator (VCO) is important for the signal integrity of wireless communication terminal. A low phase noise wideband VCO for a wireless local area network (WLAN) application is presented in this paper. A 6-bit coarse tune capacitor bank (capbank) and a fine tune varactor are used in the VCO to cover the target band. The simulated oscillation frequency tuning range is from 8.6 to 11.6 GHz. The proposed VCO is desgned using 65 nm CMOS technology with a high quality (Q) factor bondwire inductor. The VCO is biased with 1.8 V VDD and shows 9.7 mA current consumption. The VCO exhibits a phase noise of –122.77 and -111.14 dBc/Hz at 1 MHz offset from 8.6 and 11.6 GHz carrier frequency, respectively. The calculated figure of merit(FOM) is -189 dBC/Hz at 1 MHz offset from 8.6 GHz carrier. The simulated results show that the proposed VCO performance satisfies the required specification of WLAN standard.

Design and analysis of 4 × 4 MIMO antenna with DGS for WLAN applications

AbstractIn this paper, a low profile 4 × 4 multiple input and multiple output (MIMO) antenna is proposed and designed for wireless local area network (WLAN) application using a square split-ring resonator. Initially, a single square-patch antenna is designed with square-shaped split-ring slot. Subsequently, the two-element MIMO antenna is designed and it is extended to four-element MIMO antenna. Finally, the defected ground structure (DGS) is implemented in order to enhance antenna performance. The antenna elements are placed opposite to each other. The mutual coupling between the antennas elements is reduced by DGS. The proposed single, two and four-element antennas operate at 5.8 GHz for WLAN. The overall performance is measured in terms of S parameter, radiation pattern, and envelope correlation coefficient. The simulated results are verified through measurements. The simulated and measured results demonstrate that the proposed 4 × 4 MIMO antenna is the most suitable for WLAN applications.

Dual-Band Flexible Antenna for WLAN/WiMAX Applications

Aim: This paper presents the development of Co-Planar Waveguide (CPW) fed dualband, compact, and flexible antenna. The antenna is designed on flexible substrate jeans; so, it is suitable for wearable applications. Objective: The proposed antenna generates dual-band at 3.36GHz –3.61GHz and at 5.01 GHz – 5.18 GHz. The antenna has a compact size of 40×30 mm2. The antenna consists of a rectangular patch having a slot which is responsible for the first band and slot in the ground plane which is responsible for the second band. Methods: By optimizing the dimensions, the antenna gives dual-band at 3.5 GHz and 5.1 GHz with impedance bandwidth of 250 MHz and 170 MHz, respectively. The performance of the antenna such as gain and radiation pattern over the operating band has been also discussed. Conclusion: This proposed antenna with the first band at 3.5GHz is suitable for Wi-MAX (Worldwide Interoperability for Microwave Access) and second band at 5.1GHz is suitable for Higher Wireless Local Area Network applications (WLAN).

A Software-Defined Networking Solution for Transparent Session and Service Continuity in Dynamic Multi-Access Edge Computing

Multi-Access Edge Computing (MEC) will allow implementing low-latency services that have been unfeasible so far. The European Telecommunications Standards Institute (ETSI) and the 3rd Generation Partnership Project (3GPP) are working towards the standardization of MEC in 5G networks and the corresponding solutions for routing user traffic to applications in local area networks. Nevertheless, there are neither practical implementations for dynamically relocating applications from the core to a MEC host nor from one MEC host to another ensuring service continuity. In this paper we propose a solution based on Software-Defined Networking (SDN) to create a new instance of the IP anchor point to dynamically redirect User Equipment (UE) traffic to a new physical location (e.g. an edge infrastructure). We also present a novel approach that leverages SDN to replicate the previous context of the connection in the new instance of the IP anchor point, thus guaranteeing Session and Service Continuity (SSC), and compare it with alternative state replication strategies. This approach can be used to implement edge services in 4G or 5G networks.

Performance enhancement of circularly polarized patch antenna using slotted circular EBG-based metasurface

Abstract A 3 × 3 slotted circular Electromagnetic Band gap based Metasurface (SCEBG-MS) has been presented in this article, which enhances the performance of a circularly polarized (CP) patch antenna by improving its impedance bandwidth, axial ratio bandwidth and gain. The proposed antenna is having a low profile of 0.065 λ o (λ o is the free-space wavelength at center frequency of 6.16 GHz) with ground size selection of 30 × 30 mm. The prototype antenna achieves a measured −10 dB impedance bandwidth of 37% (5.02–7.30 GHz) and measured 3-dB axial ratio bandwidth of 5.9% (5.24–5.56 GHz). Furthermore, the antenna yields a good peak gain of 6.6 dBic in the CP bandwidth which makes it a promising candidate for Wireless Local Area Network (WLAN) applications. Experimental results obtained from the fabricated prototype closely matched with the simulated results.

A Low-Profile Half-Mode Annular Microstrip Antenna With Pattern Diversity

A low-profile microstrip antenna with pattern diversity is proposed in this letter. By setting the inner boundary of an annular microstrip patch as short-circuit, a half-mode annular ring antenna is obtained, whose two resonant modes, i.e., TM11 and TM01 modes, with different radiation patterns can degenerate. Besides, the shorting boundary also contributes a low coupling between the antenna and the other circuits in the center of the annular ring. The antenna is designed based on characteristic equations of the cavity model and also verified by characteristic mode analysis. The final prototype has three ports, representing two orthogonal broadside patterns and a conical pattern. All the ports can cover the 5.8 GHz Industrial, Scientific, and Medical (ISM) band. Isolations between all the ports are higher than 15 dB, and the envelope correlation coefficients are lower than 0.08, which ensure an excellent diversity performance. Numerical and experimental results agree well and prove the function of the proposed design. Due to the simple topology and the competitive performance, the proposed antenna will be a suitable candidate for ISM applications in a wireless local area network.

A multi-slotted antenna for LTE/5G Sub-6 GHz wireless communication applications

AbstractThis paper presents a low-profile multi-slotted patch antenna for long term evolution (LTE) and fifth-generation (5G) communication applications. The studied antenna comprised of a stepped patch and a ground plane. To attain the required operating band, three slots have been inserted within the patch. The insertion of the slots enhances the capacitive effect and helps the prototype antenna to achieve an operating band ranging from 3.15 to 5.55 GHz (S11 ≤−10 dB), covering the N77/N78/N79 for sub-6 GHz 5G wireless communications and LTE bands of 22/42/43/46. The wideband antenna presented in this paper offers omnidirectional stable radiation patterns, good gains, and efficiency with a compact size which make this design an ideal contender for wireless fidelity (WiFi), wireless local area network (WLAN), LTE, and sub-6 GHz 5G communication applications.

A miniaturized high gain dipole array antenna for 2.4/5 GHz wireless local area network applications

AbstractA miniaturized high gain dipole array antenna for 2.4/5 GHz wireless local area network (WLAN) applications (2.4‐2.5/5.15‐5.85 GHz) is proposed in this paper. The proposed antenna is composed of a 1 × 3 dipole array, a U‐shaped branch, and a double‐layer feedline. Dual‐band operation is realized by using a double‐branch dipole. The peak gain of the proposed dipole array antenna is improved due to the in‐phase current distributions on dipole elements. A U‐shaped branch is added to further enhance the peak gain in the lower band. For miniaturization, the half‐cutting method is applied. One prototype of the proposed miniaturized antenna with a size of 168 × 10.5 × 0.6 mm3 is manufactured and measured. As a result, the proposed antenna provides the operating bands of 2.30 to 2.59 GHz and 5.10 to 6.73 GHz (voltage standing wave ratio ≤ 2), fully covering 2.4/5 GHz WLAN band. Over the lower/higher band, the peak gain and efficiency are higher than 4.2/5 dBi and 58%/49%, respectively. Furthermore, good omnidirectional radiation characteristic in the horizontal plane is achieved.

Mutual Coupling Reduction in Microstrip Antennas using Defected Ground Structure

A Multiple Input Multiple Output (MIMO) antenna with high isolation is proposed in this paper. The proposed antenna includes two sets of four elements (2 x 2) and it is yielded at the central frequency of 5.5 GHz for Wireless Local Area Network (WLAN) applications. Based on RT5880 with height of 1.575 mm, the overall size of MIMO antenna is 140 x 76 x 1.575 mm3. To get high isolation between antenna elements, a Defected Ground Structure (DGS) is integrated on ground plane. Besides, the MIMO antenna witnesses a large bandwidth of 9.1% and an efficiency of 90% while the pick gain is 8.5 dBi. The measurement results are compared to simulation ones to verify the performance of the proposed antenna.

Split labeling diversity for wireless half-duplex relay assisted cooperative communication systems

Labeling diversity (LD) is a well-known technique proposed for multi-antenna Wireless local area network (WLAN) applications . In this paper, we propose LD for three-terminal cooperative communication schemes i.e., Decode and Forward (DF) and Coded-cooperative (CC) schemes with each terminal using a single antenna for transmission. The Boosted space-time codeword is jointly constructed by source and a relay node in two phases and joint iterative detection and decoding are used at the destination node. This technique shows that the gains from LD can be further enhanced when used in cooperative communication schemes. Numerical analysis reveal that the proposed schemes DF and CC provide full diversity gains, over non-cooperative schemes, later scheme being the most successful one, under identical conditions using less number of antennas at each communication node and with reduced receiver complexity.

A miniaturized electromagnetically coupled patch antenna design using eroded ground plane

AbstractA novel electromagnetically coupled circular patch antenna (CPA) with an eroded ground plane is proposed for the wireless local area network (WLAN) application. First, a simple CPA is designed for 2.4‐GHz WLAN band. At this frequency, the physical size of the CPA is large. Therefore, a CPA is designed at a higher frequency with much lesser dimensions, and some portion of the ground plane is eroded to observe the percentage of resonant frequency reduction. In order to avail the WLAN services at 2.4 GHz, a CPA is optimally designed at 5.76 GHz based on the same proportionality technique with an eroded ground plane. This miniaturized antenna resonates at 2.4 GHz frequency with excellent reflection and radiation characteristics. The simulation software ANSYS high‐frequency structure simulator is considered for the design of the proposed CPA. The CPA is physically fabricated and its characteristics are validated with the simulation result. It is also compared with some of the antennas available in the literature for the WLAN application. The comparative study shows that the proposed CPA is a miniaturized one with attractive performance parameters.

High-gain low-profile rectangular microstrip patch antenna with Yagi elements

ABSTRACT This paper presents a novel high gain rectangular microstrip patch antenna (RMSA) with vertically placed Yagi elements. The antenna is fed by a coaxial probe to excite TM01 fundamental waves at 2.4GHz, which is suitable for wireless local area network (WLAN) applications. In order to increase the antenna gain, Yagi elements are placed in groups of 5, on each side of the substrate in order to serveas directors for the radiating slots as well as the ground reflections. The proposed antenna offers 1.3dB gain improvement and %3 .1 impedance bandwidth increase in comparison to the plain rectangular microstrip antenna with the same specifications. The advantage of this antenna is to provide an easy and cost effective solution to increase microstrip antenna gain, particularly in 8-10dB range, without disruptingits planar structure.