Ultra-wideband Communication Systems Research Articles

Enhanced Ultra-Wideband Communication System with OFDM Modulation: Performance Analysis in LOS and NLOS Conditions

Ultra-wideband (UWB) communication systems, employing Orthogonal Frequency Division Multiplexing (OFDM) modulation, are renowned for their high data rates, low power consumption, and robust performance in multipath environments. However, these systems face significant challenges in varying propagation conditions, specifically under Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) scenarios. In LOS conditions, the signal travels directly from the transmitter to the receiver without obstructions, typically resulting in optimal performance characterized by high transmission efficiency, strong Signal-to-Noise Ratio (SNR), low Bit Error Rate (BER), and maximum throughput. Conversely, NLOS conditions involve obstructions and reflections that cause multipath propagation and signal degradation. This leads to reduced transmission efficiency, lower SNR, higher BER, and diminished throughput. This study examines the performance of an UWB communication system using OFDM modulation in both LOS and NLOS conditions. The performance metrics evaluated include transmission efficiency, SNR,BER, and throughput. In LOS conditions, the system demonstrates high transmission efficiency, superior SNR, minimal BER, and maximum throughput due to the unobstructed signal path. In contrast, NLOS conditions result in decreased transmission efficiency, lower SNR, increased BER, and reduced throughput due to signal attenuation and multipath effects. These findings highlight the significant impact of environmental conditions on UWB-OFDM system performance and underscore the importance of optimizing such systems for reliable communication in varied deployment scenarios.

A compact tri-notched flexible UWB antenna based on an inkjet-printable and plasma-activated silver nano ink

The rapid development of ultrawideband (UWB) communication systems has resulted in increasing performance requirements for the antenna system. In addition to a wide bandwidth, fast propagation rates and compact dimensions, flexibility, wearability or portability are also desirable for UWB antennas, as are excellent notch characteristics. Although progress has been made in the development of flexible/wearable antennas desired notch properties are still rather limited. Moreover, most presently available flexible UWB antennas are fabricated using environmentally not attractive subtractive etching-based processes. The usage of facile additive sustainably inkjet printing processes also utilizing low temperature plasma-activated conductive inks is rarely reported. In addition, the currently used tri-notched flexible UWB antenna designs have a relatively large footprint, which poses difficulties when integrated into miniaturized and compact communication devices. In this work, a silver nano ink is used to fabricate the antenna via inkjet printing and an efficient plasma sintering procedure. For the targeted UWB applications miniaturized tri-notched flexible antenna is realized on a flexible polyethylene terephthalate (PET) substrate with a compact size of 17.6 mm × 16 mm × 0.12 mm. The antenna operates in the UWB frequency band (2.9–10.61 GHz), and can shield interferences from WiMAX (3.3–3.6 GHz), WLAN (5.150–5.825 GHz) and X-uplink (7.9–8.4 GHz) bands, as well as exhibits a certain of bendability. Three nested "C" slots of different sizes were adopted to achieve notch features. The simulation and test results demonstrate that the proposed antenna can generate signal radiation in the desired UWB frequency band while retaining the desired notch properties and having acceptable SAR values on-body, making it a viable candidate for usage in flexible or wearable communication transmission devices. The research provides a facile and highly efficient method for fabricating flexible/wearable UWB antennas, that is, the effective combination of inkjet printing processing, flexible substrates, low temperature-activated conductive ink and antenna structure design.

A Hybrid Differential Detection Scheme for the Ultra-Wideband Orientational Beamforming System

Differential space-time coding methods have been investigated for ultra-wideband communication systems to avoid channel estimation. However, their performance in the line-of-sight (LOS) environment is worse than the recently proposed orientational beamforming (OBF) system under low signal-to-noise ratios (SNRs). On the other hand, the OBF system cannot work well in the non-LOS (NLOS) environment. To address these issues, a hybrid differential detection (HDD) scheme is proposed in this paper, which combines the OBF system with a proposed differential OBF (DOBF) system. First, the DOBF system with a fully differential detection scheme is proposed, whose performance is almost the same as the differential space-time block coding method. However, its detection complexity only linearly increases with the number of transmitting antennas. Then, the HDD scheme is proposed, with its decision statistic being a combination of a modified OBF decision statistic and the DOBF decision statistic. In the NLOS environment, the HDD scheme is reduced to the DOBF system. In the LOS environment, a combination coefficient is obtained by mapping an SNR-related factor through a sigmoid function. The optimal parameters for the sigmoid function are determined through simulations, with which the proposed HDD scheme can achieve overall better performance than the OBF and DOBF systems.

A planar BPF for UWB communication systems with single/multiple interference rejection bands

Abstract The design and development of a microstrip-based planar ultra-wideband (UWB) bandpass filter (BPF) with single/multiple interference rejection capability is presented. The proposed BPF structure is developed based on the broadside coupled mechanism of microstrip/coplanar waveguide (CPW). The BPF has microstrips and short-circuited CPW capacitively coupled through the substrate. The basic frequency response generated from this geometry covers the necessary UWB spectrum (3.1–10.6 GHz) and possesses appreciable characteristics due to dual transmission zeros at either passband boundary. Multiple resonators are embedded in the basic BPF structure to develop passband notches to circumvent unnecessary interferences. A low-pass filter is later integrated into geometry to extend the upper stopband. The proposed structure is compact and covers an area of only 14 × 11.4 mm2.

Feasibility of Ultra-Wideband Channels at Millimeter Wavelengths Faded by Rain in GeoSurf Satellite Constellations

We have studied the interference caused by amplitude and phase distortions induced by rain in ultra-wideband communication systems designed for using amplitude modulation in GeoSurf future satellite constellations. The results concern radio links simulated with the synthetic storm technique at Spino d’Adda (Italy), Madrid (Spain) and Tampa (Florida), which are sites located in different climatic regions. The conclusions are (a) the three sites, although in different climatic zones, are practically indistinguishable; (b) the channel signal-to-noise ratio can be increased or decreased by interference with equal probability. Channel theoretical capacity loss, even in the worst case, is very limited and rain, therefore, does not cause significant linear distortions in ultra-wideband channels at millimeter waves; therefore, these channels could be used at millimeter waves.

Adaptive Equalization for UWB communication System based on ANFIS

Ultra-wideband (UWB) communication systems cover enormous bandwidths that have strongly low-power spectral densities. At UWB communication system with high data rate, owing to multipath propagation, the spread delay in inter symbol interference (ISI) will raise the bit error rate (BER) considerably. ISI which is formed via the UWB channels can be removed by equalization, which is one of the most significant signal processing techniques. Furthermore, LMS algorithm represents a very efficient tool for determining adaptive equalizer coefficients values in communication systems, in spite of that, the LMS adaptive equalizer encounters response diminishing besides slow convergence rate. The current paper adopts an adaptive equalizer based adaptive neuron-fuzzy inference system (ANFIS). The simulation outcomes reveal that the convergence rates as well as accuracy of identification of ANFIS based algorithm are surpass the traditional LMS algorithm, moreover, simulation outcomes prove that ISI is effectively limited and the performance of the system is clearly improved.

An ultra-wideband low noise amplifier with cascaded flipped-active inductor for cognitive radio applications

Cognitive radio (CR) is an ultra-wideband communication system with a 50 MHz to 10 GHz frequency band that intelligently optimizes the use of the available frequency spectrum using dynamic spectrum monitoring. This paper proposes a differential ultra-wideband low-noise amplifier using two cascaded flipped-active inductors (CASFAI-LNA). The structure of each CASFAI consists of two transistors (gyrator-capacitor) and a common gate pMOS in its feedback path. The use of the capacitor cross-coupling method increases the transconductance of the circuit, which in addition to improving the gain and the noise figure, reduces the current consumption of the circuit. In addition, the biasing of active inductors from the feedback path reduces the power consumption of the circuit. This circuit is designed and validated in Cadence using a 0.18 μm CMOS process. The post-layout simulation results show that in the whole desired bandwidth (CR frequency range), the input matching is better than −10 dB, the maximum power gain is higher than 10.6 dB, the minimum noise figure is 2.24 dB, the stability factor is higher than 2.8, and the maximum IIP3 is −2.3 dBm. The proposed LNA consumes 6.12 mW from a 1.8 V DC supply.

Printable Silver Nano Ink for Bendable Ultrawideband Antenna with Triple-Notch Characteristics

Flexible antennas based on the printed flexible electronic technology are of great interest for important applications in wireless communication systems due to their distinctive features over traditional rigid-based antennas. The ultrawideband (UWB), notch characteristics, and bending capabilities of such antennas are crucial for flexible and wearable applications. Currently, only a few are focused on the printed flexible electronics technology with printable ink materials for UWB antenna applications. In addition, flexible UWB antennas with triple-notch characteristics and good bending performance are rarely reported. Thus, there is a need to make advances in this area. Here, we describe the application of a printable silver nanoparticle-based ink for rapidly fabricating an antenna with bendable and triple-notch characteristics designed for UWB communication systems. The ink, composed of monodisperse silver nanoparticles, isopropanol, and ethyl glycol, can easily produce favorable conductive patterns at a sintering temperature below 130 °C after inkjet printing. The antenna is designed on a flexible polyethylene terephthalate (PET) substrate and has a moderate size of 27 mm × 38 mm × 0.12 mm. It operates at a frequency range of 1.9–10.75 GHz, which covers the desired UWB frequency band. By loading a “U”-like slot and two “C”-like slots on the radiating patch, band rejections were generated at 3.2–3.8, 5.3–6.2, and 7.8–8.5 GHz, shielding the interference from world interoperability for microwave access, wireless local area networks, and X uplink bands. The bending results show that the antenna retains good UWB and triple-notch performance even after bending along the Y- or X-axis for different degrees. An antenna prototype was finally fabricated by inkjet printing of the silver nano ink on the PET substrate, exhibiting the desired notch characteristics and excellent bendability. The fabricated antenna prototype proved the feasibility of use as a flexible device at an ultrawide frequency band. The research provides a design guide for flexible antennas with notch features toward flexible and wearable electronics.

Design of double-notch UWB filter with upper stopband characteristics based on ACPW-DGS.

In this manuscript, a compact (size only 9.8mm*9.8mm) Ultra Wide Band (UWB) bandpass filter with a new structure is proposed, which can be used in the UWB wireless communication band authorized by the FCC. The top plane is composed of a pair of back-to-back microstrip lines, and the ground plane structure is based on an asymmetric coplanar waveguide-defect ground structure (ACPW-DGS). UWB is formed by the vertical electromagnetic coupling of the top plane and the ground plane. On this basis, split ring resonator (SRR) and C type resonator (CTR) are utilized to place double notch bands. A novel third order nested C-type resonator (TONCTR) is obtained by performing CTR, which can further optimize the upper stopband while ensuring double notch bands. The filter can be used for filtering within the UWB system, and it can also avoid the amateur radio band (9.2 -10.3GHz) and the X-band satellite link band (9.6-12.3GHz) on UWB communication systems. Finally, the measured results from the fabricated prototype are basically consistent with the simulation results.

A novel dual-BJT avalanche pulse generator with mixer effect

AbstractThis paper presents a novel, simple, and efficient pulse generation technique using BJTs in avalanche mode with mixer effect. The presented design is an improved version of the basic single transistor avalanche pulse generator, and it composes of two identical pulse generators that drive a common 50-Ω load resistor at the output. The output signal exhibits wider bandwidth and narrower pulsewidth, compared to the basic single transistor circuit. The presented pulse generator also provides increased power output without using any power amplifier, and can be used in ground-penetrating radar and ultra-wideband communication systems.

Comparative Study of High Speed ADCs

With the development of information technology, analog-to-digital converter (ADC) is widely used. In products such as radar, ultra wideband communication system, high-performance digital oscilloscope and so on, the speed performance of analog-to-digital converter is usually the bottleneck of the whole system performance, so the research of high-speed ADC has attracted much attention. ADC is an interface circuit that converts analog signals into digital signals that can be processed by DSP. This paper will start with the basic knowledge of ADC, explain the general working process of ADC, introduce several architectures and working principles suitable for high-speed ADC, and compare and analyze their advantages and disadvantages.

A Trajectory-Based Gesture Recognition in Smart Homes Based on the Ultrawideband Communication System

In this article, a cost-effective ultrawideband (UWB) communication system for gesture recognition in a smart home environment is proposed, which uses gesture trajectories and a deep learning model. Most previous studies of gesture recognition using the UWB technology used electromagnetic signals directly, which may bring problems, such as radar clutter, signal coupling, multipath, fading, and interference. However, instead of using UWB’s high-frequency pulse signals, the proposed method only uses gesture trajectories by data positioning. To this end, first, a data set of four gesture activities was created. Then, this data set was trained using a convolutional neural network (CNN) integrated with a squeeze-and-excitation (SE) block, namely, the SE-Conv1D model. Finally, the system was prototyped to interact with appliances in practical smart homes. The experimental data was used to demonstrate the superiority of the SE-Conv1D model in comparison with four baselines: 1) support vector machines; 2) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -nearest neighbor; 3) random forest; and 4) binarized neural networks. Experimental results show that all collected gesture activities are correctly recognized with an overall accuracy of over 95%, among which the proposed SE-Conv1D model achieves the best accuracy of 99.48%. The proposed system is a complete end-to-end sensing system specifically designed for tracking and recognizing human gestures, which is robust against interference and changes in distance or direction. In addition, the proposed system can tackle the device selection problems for smart homes, which means it is reliable for real-world applications.

Frequency Division Multiplexer With Directional Filters in Multilayer LCP Films at - and -Band

A quasi-reflectionless frequency division multiplexer (FDM) with directional filters (DFs) in multilayer liquid crystal polymer (LCP) substrates is proposed for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> - and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula> -band applications. The in-series cascaded DFs are designed at 74, 84, and 94 GHz, each of which comprises two microstrip lines in the first layer, two pairs of coupling slots in the second layer, and loop resonators in the third layer. The distance between DFs is optimized for suppressing reflection and insertion losses, and the asymmetric distribution of DFs is designed to obtain a low profile. The experimental data demonstrate a 3-dB passband of 8.3%, 8.8%, and 9.7% centered at 74, 84, and 94 GHz, respectively, for the proposed FDM, showing a good match with the simulation. The corresponding insertion loss is measured as 3.63, 3.4, and 2.72 dB at 74, 84, and 94 GHz, respectively. The proposed device may find many applications in multiband and ultrawideband communication and radar systems.

Electrically Small Circularly Polarized UWB Intraocular Antenna System for Retinal Prosthesis.

This paper presents the design of an electrically small circularly polarized (CP) 3 × 3 mm2 antenna system as an intraocular unit for retinal prosthesis application. The system is operating in ISM and ultra-wideband (UWB) bands to target high programmability of retina stimulation and recording, respectively. The electrical dimensions, including the ground plane, are λ0/41 × λ0/41 × λ0/191. Physical limitations of the antenna are discussed based on Hansen and Collin's limitations. The proposed wire patch antenna exhibits wideband characteristics by combining multiple modes of the patch antenna in the presence of an interface PCB circuit. By loading polyimide encapsulated patch with stubs, dominant TM010 mode is combined with the higher order modes TM020-TM070 to exhibit wide -10 dB impedance bandwidth of 2-11 GHz. Annular rings and shorting pins in the ground plane provide CP radiation at 2.45, 5.8, and 8 GHz with 3-dB axial-ratio bandwidth of 0.3, 0.16, and 1.2 GHz, and far-field left hand circularly polarized (LHCP) gain of -18.4, -7.6, and -4.7 dBic, respectively, in broadside direction. A biocompatible antenna system is designed using Ansys HFSS in the presence of a detailed multilayer canonical eye model. Additionally, it is examined in an anatomical HFSS head model. Near and far-field electric field distribution is studied along with peak 1-g average specific absorption rate (SAR) calculations. The proposed antenna is fabricated, and the performance, including coupled power from an external antenna, is measured in a custom made eye model including head phantom. A reasonable agreement is obtained between simulated and measured results. To generate an artificial vision, image perception capability could be improved with implantable UWB communication systems that feature particularly high data-rate and small size.

Compact Cauliflower-Shaped Antenna for Ultra-Wideband Applications

A compact coplanar waveguide (CPW) fed cauliflower-shaped antenna is presented and discussed in this paper. To extend the impedance bandwidth and to improve the impedance matching, fractal geometry having a cauliflower shape is introduced along the edges of the radiator. To validate the simulated results by experimental ones, a prototype of the designed antenna was fabricated on the RO-4350B substrate having a compact size of 0.3623λ0 × 0.41λ0 × 0.01524λ0 at 3 GHz. An Agilent 8722ES vector network was used for the reflection coefficient measurement revealing that the –10 dB bandwidth of the fabricated antenna offers an impedance bandwidth of 113% extending from 3.05 to 10.96 GHz. Besides, the antenna’s radiation patterns are measured in an anechoic chamber showing consistent radiation patterns characteristic over the entire working band. Furthermore, the proposed antenna has a peak gain of around 6 dBi and an average radiation efficiency almost over 90% across the entire operating band. Thus, the proposed antenna could be useful in many modern ultra-wideband (UWB) communication systems.

Orthogonal Delay Scale Space Modulation: A New Technique for Wideband Time-Varying Channels

Orthogonal Time Frequency Space (OTFS) modulation is a recently proposed scheme for time-varying narrowband channels in terrestrial radio-frequency communications. Underwater acoustic (UWA) and ultra-wideband (UWB) communication systems, on the other hand, confront wideband time-varying channels. Unlike narrowband channels, for which time contractions or dilations due to Doppler effect can be approximated by frequency-shifts, the Doppler effect in wideband channels results in frequency-dependent non-uniform shift of signal frequencies across the band. In this paper, we develop an OTFS-like modulation scheme -- Orthogonal Delay Scale Space (ODSS) modulation -- for handling wideband time-varying channels. We derive the ODSS transmission and reception schemes from first principles. In the process, we introduce the notion of -convolution in the delay-scale space that parallels the twisted convolution used in the time-frequency space. The preprocessing 2D transformation from the Fourier-Mellin domain to the delay-scale space in ODSS, which plays the role of inverse simplectic Fourier transform (ISFFT) in OTFS, improves the bit error rate performance compared to OTFS and Orthogonal Frequency Division Multiplexing (OFDM) in wideband time-varying channels. Furthermore, since the channel matrix is rendered near-diagonal, ODSS retains the advantage of OFDM in terms of its low-complexity receiver structure.

Design of Ultra-Wideband (UWB) Bandpass Filters Based on Interdigital Edge Coupled Lines: A Review

Since several decades ago, parallel coupled lines have found an extensive range of applications in order to design microwave circuits such us filter, impedance transformers and couplers. It gives advantages in term of low cost, easier integration with other devices and controllable performances by changing coupling coefficient between lines. This paper presents a review of parallel two and three interdigital coupled lines bandpass filters for ultra-Wideband (UWB) communication systems during previous years to achieve a fraction passband from 3.1 GHz to 10.6 GHz and then a FBW that can reach 109%. Different structures such as multiple-mode resonator, Short Circuited Stubs, Open stub, Stepped-impedance resonators and Rectangular Ring have been reportedly used to ameliorate the performances of developed filters.

Design and research of a miniaturized four notch UWB antenna

In order to effectively suppress the interference of narrow-band communication systems such as WiMAX band, international satellite band, X band and the ITU band, this paper designs a miniature ultra wideband (UWB) antenna. The improved rectangle is used as the radiation patch. The semicircular groove is dug in the upper part of the rectangle and the two corners below are cut off. The long triangle is also cut on both sides of the end of the microstrip line. The fish bone groove is well modified in the middle of the rectangular ground plate to obtain the perfect ultra wideband characteristics. By digging a semi-circular groove on the radiation patch to introduce T-shaped branches, and opening an inverted U-shaped groove in the center of the radiation patch, introducing symmetrical C-shaped open branches on both sides of the feeder line and etching U-shaped narrow gaps on the feeder line, four band notch characteristics of 3.24−3.8 GHz, 4.5−4.97 GHz, 7.24−7.76 GHz and 8.0−8.54 GHz are produced, which better suppresses the interference in the notch band, shows that the antenna can work normally in the frequency band of 3.0−13.09 GHz, and the four notch baud property of the antenna also expands the application field, which is suitable for many ultra wideband communication systems.

Ku대역과 밀리미터 대역의 광대역 무선통신 시스템을 위한 소형 슬롯 6각 구조의 패치 안테나

본 논문에서는 초광대역의 소형 슬롯 6각 구조의 패치 안테나가 12×9×0.787 ㎣ (1.64λ×1.23λ×0.107λ)로 설계되었다. 본 논문에서는 위성통신과 66.67%의 중심 주파수 비 대역폭을 가지는 미래 ㎜-Wave 어플리케이션을 위해 (30 ~ 52) ㎓의 대역보다 더 넓은 초광대역 통신을 위해 슬롯 6각 구조의 ground plane이 Ku대역 주파수(17.608 ~ 19.64) ㎓에서 동작되도록 제시했다. 안테나는 37 ㎓의 ㎜-Wave 주파수 대역을 포함하여 다양한 주파수에서 공진한다. 제안된 안테나의 최대 이득은 6.282 ㏈이다.

Sextuple band rejection functionality from a compact Koch anti-snowflake fractal UWB-MIMO antenna integrated with split-ring resonators and slots

In this article, a dual-port modified Koch Anti-snowflake fractal antenna is designed and experimentally verified for ultra-wideband performance with hexa-band suppression functionality. The designed array occupies a total area of 29.5 × 43.5 mm2. Initially, it consists of two microstrip-fed modified Koch Anti-snowflake fractal (iterated up to 3rd order) patches and a defected ground plane, aimed to achieve 144.6% fractional bandwidth (2.48–15.42 GHz) with optimum isolation characteristics (S21/S12 ≤ -17 dB). The proposed fractal geometry minimizes the patch area by 42.4% as compared to the circular configuration. Further, each fractal patch is embedded with a Z-shaped and inverted L-shaped slit to suppress the unwanted WiMAX (3.3–3.77 GHz) and INSAT (4.57–4.9 GHz) band respectively. Two SRR pairs and a G-shaped slot are loaded in each feedline of the designed array to realize notches at 6.578 GHz (super-extended C-band), 8.23 GHz (ITU-8), and 10.22 GHz (amateur radio) respectively. A pair of L-shaped slits is removed from the reduced ground to eliminate the interfering WLAN (5.18–5.82 GHz) band. Various diversity parameters for the designed array are examined and are found within their permissible levels. The experimental results of the fabricated array (without and with notch elements) present an acceptable resemblance with the simulated ones, therefore assuring the practicability of the designed array in ultrawideband communication systems.