Unlicensed National Information Infrastructure Band Research Articles

A Metamaterial Loaded Microstrip Patch Antenna for Lower 5G U-NII Spectrum

In this study, we have proposed a metamaterial loaded microstrip patch antenna for the sub-6 GHz range to operate in the Unlicensed National Information Infrastructure (U-NII) band. The Proposed Microstrip Patch Antenna (PMPA) has a U-shaped patch and an array of Complementary Split Ring Resonators (CSRR) in the ground plane. By adding a slot in the middle, the rectangular patch becomes a U-shaped one which is responsible for the enhancement of antenna bandwidth and gain. Our antenna provides a bandwidth of 392 MHz which is about 2.7 times larger compared to that of a Conventional Microstrip Patch Antenna (CMPA) of the same dimension. The maximum gain of our antenna is found 6.56 dB which is around 2 dB higher than that of the conventional one (4.72 dB). Due to the addition of the CSRR array in the ground plane, an improved impedance matching of 50 ohms has been achieved. The operating frequency range of the PMPA is from 5.525 to 5.917 GHz which can be used for 5G applications such as Wi-fi, Wi-Max, and IoT devices in the U-NII band.

Harmonious Cross-Technology Coexistence With Heterogeneous Traffic in Unlicensed Bands: Analysis and Approximations

The dramatic growth in demand for mobile data has prompted mobile network operators (MNOs) to explore spectrum sharing in unlicensed bands. MNOs have been allowed recently to operate their LTE services over the 5 GHz Unlicensed National Information Infrastructure (U-NII) bands, currently occupied by Wi-Fi. The unlicensed LTE operation has been standardized by 3GPP under the name Licensed Assisted Access (LAA). Unlicensed 5G New radio (NR) operation over the U-NII bands, a.k.a., NR-Unlicensed (NR-U), is also being explored. To support applications with diverse Quality-of-Service (QoS) requirements, LAA, NR-U, and Wi-Fi technologies offer multiple priority classes with different contention parameters for accessing an unlicensed channel. How these different classes affect the interplay between coexisting MNOs and Wi-Fi systems is still a relatively under-explored topic. In this paper, we develop a simple yet efficient framework for fair coexistence between LTE MNOs and Wi-Fi systems, each with multiple priority classes. We derive approximated closed-form solutions for the probability of successful transmission (PST), average contention delay, and average throughput when coexisting LAA and Wi-Fi devices serve traffic with different priority classes. LTE and Wi-Fi operators can fit our solutions to estimate the performance of both systems in offline or online fashions, and use them to further optimize their system throughput and latency. Our results reveal that PSTs computed with our approximate models are within 5% difference with those obtained via close-to-real simulation under dense network deployments and high traffic loads.

CPW fed rectangular rings-based patch antenna with DGS for WLAN/UNII applications

AbstractThe spectral congestion in existing Industrial, Scientific, and Medical (ISM) Wireless Local Area Network (WLAN) bands has led to the emergence of new ISM bands (Unlicensed National Information Infrastructure (UNII)) from 5.150 to 5.710 GHz. In this paper, a simple uniplanar, high gain, microstrip antenna is designed, fabricated, and tested for existing WLAN and new UNII standards. The proposed antenna provides dualband operation by joining two rectangular rings and cutting Defected Ground Structure in the Coplanar Wave Guide (CPW) feed. The experimental and simulation results show good return loss characteristics and stable radiation pattern over the desired frequency bands ranging from 2.20 to 2.65 GHz (WLAN band) at a lower frequency and from 5.0 to 5.45 GHz (UNII-1/UNII-2 bands). The measured peak gains are 5.5 and 4.9 dBi at 2.45 GHz (WLAN band) and 5.15 GHz (UNII band), respectively.

LWA in 5G: State-of-the-Art Architecture, Opportunities, and Research Challenges

To cater to the exponential increase in wireless data demands under limited availability of licensed spectrum, the Federal Communications Commission has released extra bandwidth of 295 MHz in the 5 GHz unlicensed national information infrastructure bands for wireless communications. This free, unlicensed band has drawn considerable attention from academia and cellular operators worldwide. Several standards are being developed for flexible integration, aggregation, and interworking of this unlicensed band with licensed networks or spectrum. Of many candidate approaches, in this article, we introduce LTE WLAN aggregation (LWA). LWA, capable of leveraging the LTE and WLAN spectra simultaneously, has emerged as a prominent solution to increase network capacity and enhanced end users' quality of experience. Further, we present latest advances in this exciting technology by reviewing the state-of-the-art LWA architecture, and identify several opportunities and open challenges related to LWA design for future research.

Design and development of a stacked complementary microstrip antenna with a “π”-shaped DGS for UWB, UNII, WLAN, WiMAX, and Radio Astronomy wireless applications

The proposed research paper presents the design, development, and experimental testing of a broadband stacked complementary microstrip antenna for ultra-wideband (UWB) (5.28–5.85 GHz), Unlicensed National Information Infrastructure band (UNII) (5.25–5.825 GHz), wireless local area networks (WLAN, IEEE802.11a, 5.15–5.35 GHz), and IEEE 802.11b (5.75–5.85 GHz), Worldwide Interoperability for Microwave Access band (5.25–5.85 GHz), and Radio Astronomy band (6.6–6.75 GHz) wireless applications. The main aim of this paper is to obtain an UWB behavior from the combined effect of two resonances exhibited by the driven and parasitic patches of a stacked complementary antenna geometry. Circularly polarized radiations are also emitted by the antenna by the addition of an orthogonal stub to its feed line. The proposed three-layered antenna structure (without air gap) is fabricated on commercially available glass-reinforced epoxy laminate, FR4 substrate. The topmost layer of FR4 has a square-shaped patch parasitic patch printed over it; this patch has a square slot etched out from it. The middle layer of the antenna has a square-shaped driven patch of approximately the same dimensions as that of the slot in parasitic patch. The antenna is fed using aperture-coupled feeding mechanism. Therefore the lowermost layer of FR4 has a ground plane on its top with a “π”-shaped slot etched from it and a feed line with an orthogonal stub at its bottom forming a “T”-shaped geometry. The antenna is fed by the electromagnetic coupling between the antenna layers .The proposed antenna has a compact structure with overall volumetric dimensions of 4.7 × 3.82 × 0.483 cm3. The antenna design and simulations are carried out using CSTMWSV'10 with perfect boundary (electric and magnetic) estimations. This designed antenna shows an UWB behavior from 5.14 to 5.85 GHz with an impedance bandwidth of 710 MHZ and a fractional bandwidth of 12.62% at the center frequency of band at 5.5 GHz. The radiating antenna also possesses a good gain of 4.59 dBi at the central frequency of 5.50 GHz and a 1 dB axial ratio bandwidth of 820 MHz from 5.16 to 5.98 GHz. The validation of results is done by fabrication and experimental testing of the antenna using a vector network analyzer and placing the antenna in an anechoic chamber for gain measurements. The measured results show close matching with the simulated ones and this makes the antenna well suited for the proposed wireless applications of interest, specifically in small handheld wireless communication devices.

Compact frequency selective surface with dual band response for WLAN applications

ABSTRACTIn this article, the authors propose the use of conducting patches with slots to design frequency selective surfaces (FSS) with dual bandstop for wireless LAN (WLAN) applications. The simulated results were obtained with the computer program Ansoft Designer™. A prototype of the designed FSS was built and its transmission characteristics were measured. Excellent agreement between simulated and measured results was obtained. The FSS was useful for rejecting signals from industrial, scientific, and medical and unlicensed national information infrastructure bands and it presented angular stability. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:265–268, 2015

Inverted‐E shaped monopole on high‐permittivity substrate for application in industrial, scientific, medical, high‐performance radio local area network, unlicensed National information infrastructure, and worldwide interoperability for microwave access

In this study, the simulation and measured results of coplanar waveguide (CPW)-fed inverted-E shaped monopole for application in industrial, scientific, medical (ISM), high-performance radio local area network (HIPERLAN), unlicensed National information infrastructure (UNII), and worldwide interoperability for microwave access (WiMAX) bands are presented. The CPW-fed inverted-E shaped monopole is fabricated on a high-permittivity substrate. The lower band is associated with the longer strips of the inverted-E shaped monopole whereas the higher band is associated with the middle and shorter strips of the inverted-E shaped monopole. The proposed antenna has good agreement between the measured and the simulation results. The proposed antenna has a 10 dB return loss with bandwidth 644 MHz (2033-2677 MHz) in the lower band and 1913 MHz (4815-6728 MHz) in the higher band. The proposed dual-band CPW-fed inverted-E shaped monopole covered the ISM, HIPERLAN, UNII and WiMAX bands.

Low-Power Sub-Harmonic Direct-Conversion Receiver With Tunable RF LNA and Wideband LO Generator at U-NII Bands

A low-power tunable-band sub-harmonic direct-conversion receiver covering the whole Unlicensed National Information Infrastructure band is demonstrated using 0.18-μm CMOS technology. The RF band is selected by tuning varactors at the loads of the two-stage low-noise amplifier, while a wideband octet- phase generator is applied at the local oscillator (LO) port. The band tuning of both an LC tank and a transformer and the de- sign of an optimal transformer turn ratio are fully discussed in this paper. Vertical-NPN bipolar junction transistors in a standard CMOS process are used at the mixer switching core for excellent 1/f noise performance. As a result, the receiver achieves a 48/50 voltage gain and 4.5/4.8-dB noise figure with a 1/f noise corner of 70 kHz when the RF band is tuned to 5.2/5.8 GHz, respectively. The dc current consumption of the RF front-end (including the LO buffer) is 8.5 mA at a 1.8-V supply.

Dual Band Hybrid Dielectric Resonator Antenna for Application in ISM and UNII Band

There are many commercial applications, such as mobile radio and wireless communications that use microstrip antennas. Microstrip antennas however have limitations in size, bandwidth, and efficiency. On the other hand, the dielectric resonator (DR) antenna is attractive due to its small-size, high radiation efficient, and ease of excitation.[1-3] Three dielectric properties of materials must be considered for DR antenna used: a high permittivity, a high quality factor, and a near zero temperature coefficient of resonant frequency. The size of the DR antenna decreases with increasing the permittivity of the dielectric resonator. The quality factor is representative of the antenna losses. Typically there are radiation, conduction, dielectric, and surface wave losses. Therefore the total quality factor is influenced by these losses. The DR antenna offers very high radiation efficiency due to its low dielectric loss and it has no metallic loss. A near zero temperature coefficient of resonant frequency are for high temperature stability. In traditionally, the DR with relatively small permittivity around 10 is chosen for DR antenna to enhance the radiation capability.[4-10] However, low profile DR antenna with relatively low resonant frequency can be achieved by using high permittivity. Recently, dual band antenna has been implemented for applications in WLAN (wireless local area network, 2.4–2.484 GHz), ISM (Industrial, Scientific, Medical) and Bluetooth at low band. Additionally, the dual band antenna can be applied at high band, such as HIPERLAN (high-performance radio local area network, 5.15–5.35 GHz) and Unlicensed National Information Infrastructure (UNNI) applied. In this paper, we present the design of a dual band hybrid antenna consists of a rectangular slot and a circular disk high permittivity dielectric resonator for operating at the ISM band and UNNI band. Details of the proposed antenna and experimental results are present. The characteristics of dual band hybrid antenna, such as return loss, input impedance, radiation pattern, and gain, have been measured and discussed.

Compact bandpass filters in coplanar strip lines

The authors describe a compact bandpass filter design implemented in asymmetric coplanar strip lines. For initial demonstration, it was built on print circuit boards using modified two-pole Butterworth bandpass filter topology. The novel filter design does not use bonding wires, vias or any interconnecting structure. It is not based on quarter wavelength sections either. It uses the creation of an electrode pattern on the coplanar strip electrodes to emulate an equivalent circuit. The pattern is fine-tuned using full-wave simulations. Bandpass filters for 2.4 GHz ISM (Industrial, Scientific and Medical) and 5.15–5.85 GHz UNII (Unlicensed National Information Infrastructure) bands were designed, fabricated and measured. Measurement responses agree well with full-wave simulation results. The electrode pattern can be scaled for different centre frequency and improved with fine-tuning procedure. For chip-level implementation, the filter size can be greatly reduced because of much smaller minimum electrode width.

A 1.8-V 2.4/5.15-GHz dual-band LCVCO in 0.18-/spl mu/m CMOS technology

A dual band, fully integrated, low phase-noise and low-power LC voltage-controlled oscillator (VCO) operating at the 2.4-GHz industrial scientific and medical band and 5.15-GHz unlicensed national information infrastructure band has been demonstrated in an 0.18-/spl mu/m CMOS process. At 1.8-V power supply voltage, the power dissipation is only 5.4mW for a 2.4-GHz band and 8mW for a 5.15-GHz band. The proposed VCO features phase-noise of -135dBc/Hz at 3-MHz offset frequency away from the carrier frequency of 2.74GHz and -126dBc/Hz at 3-MHz offset frequency away from 5.49GHz. The oscillator is tuned from 2.2 to 2.85GHz in the low band (2.4-GHz band) and from 4.4 to 5.7GHz in the high band (5.15-GHz band).