Ultra-wideband Radio Systems Research Articles

Tightly Coupled Array Antennas for Ultra-Wideband Wireless Systems

Tightly coupled array (TCA) antenna has become a hot topic of research recently, due to its potential of enabling one single antenna array to operate over an extremely wide frequency range. Such an array antenna is promising for applications in numerous wideband/multi-band and multi-function wireless systems such as wideband high-resolution radars, 5G mobile communications, satellite communications, global navigation satellite systems, sensors, wireless power transmission, Internet of Things, and so on. Many papers on this topic have been published by researchers internationally. This paper provides a detailed review of the recent development on TCA that utilizes the capacitive coupling. The basic principles and the historical evolution of the TCAs are introduced first. Then, recent development in the analysis and design of TCAs, such as equivalent circuit analysis, bandwidth limitation analysis, array elements, feed structures, substrates/superstrates loading, and so on, are explained and discussed. The performances of the state-of-the-art TCAs are presented and a comparison amongst some TCAs reported recently is summarized and discussed. To illustrate the practical designs of TCA, one case study is provided, and the detailed design procedures of the TCA are explained so as to demonstrate the TCA design methodology. Simulated results including the VSWR at different angles of scanning, patterns, and antenna gain are shown and discussed. A conclusion and future work are given in the end.

Symmetrical Couple F-Shaped Notches with High Rejection C-Band of UWB Patch Antenna

The ultra-wideband (UWB) antenna is developed to cover a broad bandwidth. ‎The UWB radio systems are interfered ‎by the ‎same ‎spectrum ‎that shared with the local bands. In this paper, two F-shaped slots on a hexagonal patch UWB antenna are demonstrated ‎‎ to realize a high band rejection. The symmetrical couple F-slots is ‎notched on the hexagonal UWB ‎ ‎patch antenna to avoid the interference ‎and ‎‎enhance the notching results at C-band. The demonstrated ‎antenna employs a coplanar waveguide ‎(CPW) technique to meet a fractional bandwidth of 126%. The proposed method validates ‎several ‎‎reconfigurations of the F-slot location on the demonstrated design. Six steps ‎parametric study are considered to test the slots location. The results of the proposed antenna with slots are introduced based on analytical, simulation, and ‎measurement. The total design size ‎‎28 mm × 43 mm × 1.6 ‎mm is simulated by ‎using CST Microwave Studio. The two F-slots are achieved the antenna gain of -6 dB, ‎return loss of -1.2 ‎dB, and ‎VSWR of 15.2 at the rejected band of 4 GHz. The ‎measurement results are compared with the simulation results between the three ‎prototypes. The current ‎distribution on the design is discussed at 2.88 GHz and 4 GHz frequencies. The radiation patterns illustrate ‎omnidirectional of H-plane and bidirectional of E-plane. This paper validates the slots locations to enhance the notches performance and reduce the interference.

A Novel Complex-Coefficient In-Band Interference Suppression Algorithm for Cognitive Ultra-Wide Band Wireless Sensors Networks.

With the rapid development of wireless communication systems and electronic techniques, the limited frequency spectrum resources are shared with various wireless devices, leading to a crowded and challenging coexistence circumstance. Cognitive radio (CR) and ultra-wide band (UWB), as sophisticated wireless techniques, have been considered as significant solutions to solve the harmonious coexistence issues. UWB wireless sensors can share the spectrum with primary user (PU) systems without harmful interference. The in-band interference of UWB systems should be considered because such interference can severely affect the transmissions of UWB wireless systems. In order to solve the in-band interference issues for UWB wireless sensor networks (WSN), a novel in-band narrow band interferences (NBIs) elimination scheme is proposed in this paper. The proposed narrow band interferences suppression scheme is based on a novel complex-coefficient adaptive notch filter unit with a single constrained zero-pole pair. Moreover, in order to reduce the computation complexity of the proposed scheme, an adaptive complex-coefficient iterative method based on two-order Taylor series is designed. To cope with multiple narrow band interferences, a linear cascaded high order adaptive filter and a cyclic cascaded high order matrix adaptive filter (CCHOMAF) interference suppression algorithm based on the basic adaptive notch filter unit are also presented. The theoretical analysis and numerical simulation results indicate that the proposed CCHOMAF algorithm can achieve better performance in terms of average bit error rate for UWB WSNs. The proposed in-band NBIs elimination scheme can significantly improve the reception performance of low-cost and low-power UWB wireless systems.

On the Variance-Based Detection for Impulse Radio UWB Systems

A variance detection (VD)-based impulse radio ultra-wideband (IR-UWB) system has the potential of mitigating narrowband interference (NBI), even in multipath environments. However, as a highly nonlinear system, which involves fourth-order multiplications, comprehensive analysis and evaluations of its performances have not been seen so far. In this paper, we address the issues by developing a log-normal random distribution model for the VD-based IR-UWB receiver and deriving the analytical bit-error-rate formulas for the system in both additive white Gaussian noise and CM1 multipath channels with and without NBIs for the first time. Furthermore, through both theoretical analysis and simulations, we show that the presented VD-based receivers can outperform the conventional energy-detection-based and the fourth-order detection-based receivers and have a stronger inherent ability to mitigate destructive performance degradation caused by strong NBIs. This makes the VD-based IR-UWB system a good candidate as a non-coherent IR-UWB receiver for low power and low complexity applications.

Performance Evaluation of High Data Rate M-OAM UWB Physical Layer for Intelligent Transportation Systems

In this paper, a high data rate modulation scheme for impulse radio ultra-wideband (IR-UWB) communication system using orthogonal waveforms is presented. The proposed M-state Orthogonal Amplitude Modulation (M-OAM) is evaluated under additive White Gaussian noise and indoor multipath channels IEEE.802.15. The simulation results show that the proposed system performance, in term of bit error rate (BER), is of the same order as that of the traditional UWB modulation. In addition, the M-OAM modulations provide a high data rate for short range wireless applications. Nevertheless, the multipath effect reduces the quality of transmission. Thus, the performances of three receiver architectures, that employ different pulse combining schemes, are investigated. Namely, a conventional matched filter receiver, a RAKE receiver and a minimum mean square error equalizer are considered. This study shows that the proposed M-OAM communication system offers good performances in term of quality of services, channel capacity and BER.

Ultra-Wideband Bandpass Filter using Microstrip-Coplanar Waveguide (CPW) Structure

In this paper, an ultra-wideband (UWB) bandpass filter (BPF) using Microstrip-coplanar waveguide structure (CPW) is presented. This filter consists of a microstrip line (on top), dielectric substrate (middle) and coplanar waveguide (on conductive ground). The proposed filter has been simulated and measured for UWB bandpass filter. The measured results demonstrate the UWB properties from 1.24 to 11.76 GHz (-10 dB bandwidth) and the potential to be wider. This paper also introduced another filter structure which works as a dual-band ultra-wideband (UWB) bandpass filter. The dual-band operation was implemented by integrating a stub in the coupled conductors. The resonance of the stub introduces a narrow rejection band in the UWB passband which then results in a dual band filtering. Such a dual-band UWB bandpass filter is strongly required in a practical system in order to avoid the interference between the UWB radio systems and existing radio systems. The rejection band can be easily designed to some specific frequency band by tuning the length of the stub. The measured results demonstrate the ultrawideband properties from 1.0800 GHz to 5.5157 GHz (-10 dB bandwidth) and rejected performance 5.5157 GHz to 5.6157 GHz (-10 dB bandwidth). General Terms Scattering Parameters, Insertion loss , Reflection loss.

Implementation of DSTFCs in MIMO MB-IR-UWB System

This paper implements differential space-time-frequency codes (DSTFCS) to multipleinput multiple-output (MIMO), multi-band impulse radio ultra-wideband (MB-IR-UWB) system. Four scenarios of the system operating mode have been put forward and combination of DSTFCs and the system has been studied in this paper. Through simulation, a comparison of BER performance among different scenarios and channel statements is analyzed. In addition, considered inter-symbol interference (ISI), the simulation on system with ISI and without ISI is given. Finally the conclusion that scenario 3 is more suitable to the proposed MIMO MB-IR-UWB system for it being less sensitive to ISI has been drawn.

A Novel Linear Array Antenna Based on UWB Slot Antenna

This paper introduces the novel Ultra-Wide Band (UWB) antennas for UWB applications. We used two different structures, the first is fed by micro-strip line and the second is a compact coplanar waveguide fed planar slot antenna. These designs are a small on planar antenna. The substrate used is FR4 that have the characteristics following: Permittivity εr = 4.4 Impulse Radio Ultra Wide Band systems (IR-UWB). The frequency central is 5.6 GHz and shows good characteristics for IR-UWB. The radiation pattern and gain are simulated and we compared between the different results we have obtained.

ASIC Implementation of Highly Reliable IR-UWB Transceiver for Industrial Automation

AbstractAn in-depth treatment of impulse an radio ultra-wideband (IR-UWB) wireless system is provided reviewing theoretical background, proceeding with detailed implementation procedure, and finally giving simulation and test results. This is the first research and prototyping work to be published in the field of IR-UWB that operates in the 6–8 GHz band. The aim of this work is to implement an IR-UWB wireless system for industrial automation that is robust and reliable. To achieve this, an analogue bandwidth of 250 MHz and digital baseband processing at the clock frequency 499.2 MHz were realized in a 250 nm

Multimedia sensor networks based on ultrawideband chaotic radio pulses

The requirements to transceivers, which are intended for multimedia data transmission in wireless sensor networks, and existing system characteristics are discussed. Ultrawideband wireless systems based on direct chaotic data transmission are analyzed to reveal the prospects of their application to multimedia sensor networks. The results obtained during experimental studies into video data-flow transfer, which are performed in the point-to-point mode with the use of radio relaying and through-wall transmission, are presented.

Band‐pass filter‐like antenna validation in an ultra‐wideband in‐car wireless channel

Ultra-wideband (UWB) is a very attractive technology for innovative in-car wireless communications requiring high data rates. A designated antenna, which presents a reflection coefficient (S11) matched band comparable to the band-pass filter (BPF) normally required at the transducers, plays a positive contribution in this in-car application and was validated for the scenario. The inherited BPF-like response of the antenna relaxes the specification of the front-end BPF components of the transceivers. The in-car propagation channel was modelled and used to validate the BPF-like antenna. For the modelling, a comprehensive set of well-defined measurements (using a standard antenna) were used to set-up the in-car channel simulator and simulated results were used to validate the BPF-like antenna. In addition, the performance of the UWB radio system is studied and the probability of errors over the communication channel compared using the standard and the BPF-like antenna by predictions.

Experimental Analysis of UWB Signal Performance in a Constrained Environment for Railway Application

In the railway application, in order to establish the communication between wagons, some technologies are proposed such as the ZigBee and HTN (Hybrid Networking Technology). However, these techniques have some limitations such as: the low data rate, non-secured transmission and interferences. The Ultra Wide Band (UWB) technology presents a good alternative and a good candidate for this application. In recent years, UWB communication systems have received significant attention from both the industry and the academia. In February 2002, the Federal Communications Commission (FCC) allocated 7500 MHz of spectrum (from 3.1 GHz to 10.6 GHz) for use by UWB devices. This ruling has helped to create new standardization efforts, like IEEE 802.15.3a, which focus on developing high speed wireless communication systems. The application of the UWB radio technique in the transport is a more recent topic that is thoroughly researched considering several factors including the nature of the transport propagation environment; the use of adequate transmitting/receiving duty cycle (LDC); the number of devices using UWB technology, the types and levels of interferences. Regulation bodies have considered these railway applications. Impulse Radio Ultra Wideband (IR-UWB) systems have been studied for their inherent advantages of coexistence with narrowband systems with high data rate over short distances with sufficiently small amount of transmitted power. The UWB systems are highly susceptible to interference between the coexisting narrowband systems because of very low transmission power. This paper considers the use of the UWB radio technology for railway application. In this paper, we evaluate the communication performance in constrained environment for the railway application.

A ML-Based Framework for Joint TOA/AOA Estimation of UWB Pulses in Dense Multipath Environments

We present a joint estimator of the time of arrival (TOA) and angle of arrival (AOA) for impulse radio ultrawideband (UWB) systems in which an antenna array is employed at the receiver. The proposed method consists of two steps: 1) preliminary estimation of the TOA and the average power delay profile (APDP) using energy-based threshold crossing and log-domain least-squares fitting, respectively; and 2) joint TOA refinement and AOA estimation by local 2-D maximization of a log-likelihood function (LLF) that employs the preliminary estimates from the first step. The derivation of the LLF relies on an original formulation in which the superposition of images from secondary paths is modeled as a Gaussian random process, whose second-order statistical properties are characterized by a wideband space-time correlation function. In addition to the APDP, this function incorporates a special gating mechanism to represent the onset of the secondary paths, thereby leading to a novel form of the LLF. Closed-form expressions for the Cramer-Rao bound on the variance of the TOA and AOA estimators are also derived, which formally take into account pulse overlap through this gating mechanism. In simulation experiments based on multipath UWB channel models featuring both diffuse and directional image fields, our approach exhibits superior performance to that of a competing scheme from the recent literature.

Super multi-channel recording systems with UWB wireless transmitter for BMI.

In order to realize a low-invasive and high accuracy Brain-Machine Interface (BMI) system for clinical applications, a super multi-channel recording system was developed in which 4096 channels of Electrocorticogram (ECoG) signal can be amplified and transmitted to outside the body by using an Ultra Wide Band (UWB) wireless system. Also, a high density, flexible electrode array made by using a Parylene-C substrate was developed that is composed of units of 32-ch recording arrays. We have succeeded in an evaluation test of UWB wireless transmitting using a body phantom system.

The Simulation of DS-UWB RAKE Receiver over the Multipath Channel

Ultra-Wideband (UWB) wireless communication is a new potential communication technology currently in its field. It becomes very popular in the world since it’s high performance, low radicalization and low cost. Currently UWB wireless system, we can call it Impulse Radio technology too, be invented in 20 century 1960s. But it was only used in military affairs field, bailout searching, radar location and so on. After civil using, it usually is used in indoor wireless LAN .In this paper, the development and application of UWB are introduced, the characteristic and limitation of UWB are simply analyzed. According to the simulating depending on Multipath channel, it shows increasing SNR about 1.5dB to the base of primary power district or increasing SNR about 1dB to primary power district and minor power district, we can get whole performance of RAKE receiver in perfect channel.

Planar Finger-Shaped Antenna used in Ultra-Wideband Wireless Systems

Recently, extensive requirements have developed for ultra-wideband (UWB) technology that provides high activity and small size for use in small communication systems, remote sensing, and radar applications. Thus, we concentrated with high-resolution radar UWB antenna to cover Federal Communication Commission’s (FCC) standard UWB range (3.1-10.6 GHz). The proposed ideal-size and low-cost finger-shaped patch antenna of 24 mm x 19 mm printed on 40 mm x 35 mm rectangular Taconic TLY-5 material was designed and established through experiments and simulations. Results show that the two cut notches of 1.5 mm x 2 mm at the bottom corners of the patch can increase the bandwidth. To increase the radiation area and achieve more resonance frequencies, two cut slots at the top edge of the patch were designed in depth of 10 mm. Four parameters were considered in the analysis of the proposed antenna design, namely the feeder width, number of slots, number of notches, and feed gap space. The simulated and measured results of the main antenna parameters make the design suitable in applications of UWB wireless systems.

Planar Finger-Shaped Antenna used in Ultra-Wideband Wireless Systems

Recently, extensive requirements have developed for ultra-wideband (UWB) technology that provides high activity and small size for use in small communication systems, remote sensing, and radar applications. Thus, we concentrated with high-resolution radar UWB antenna to cover Federal Communication Commission’s (FCC) standard UWB range (3.1-10.6 GHz). The proposed ideal-size and low-cost finger-shaped patch antenna of 24 mm x 19 mm printed on 40 mm x 35 mm rectangular Taconic TLY-5 material was designed and established through experiments and simulations. Results show that the two cut notches of 1.5 mm x 2 mm at the bottom corners of the patch can increase the bandwidth. To increase the radiation area and achieve more resonance frequencies, two cut slots at the top edge of the patch were designed in depth of 10 mm. Four parameters were considered in the analysis of the proposed antenna design, namely the feeder width, number of slots, number of notches, and feed gap space. The simulated and measured results of the main antenna parameters make the design suitable in applications of UWB wireless systems.

Joint Estimation of TOA and DOA in IR‐UWB System Using Sparse Representation Framework

This paper addresses the problem of joint time of arrival (TOA) and direction of arrival (DOA) estimation in impulse radio ultra-wideband systems with a two-antenna receiver and links the joint estimation of TOA and DOA to the sparse representation framework. Exploiting this link, an orthogonal matching pursuit algorithm is used for TOA estimation in the two antennas, and then the DOA parameters are estimated via the difference in the TOAs between the two antennas. The proposed algorithm can work well with a single measurement vector and can pair TOA and DOA parameters. Furthermore, it has better parameter-estimation performance than traditional propagator methods, such as, estimation of signal parameters via rotational invariance techniques algorithms matrix pencil algorithms, and other new joint-estimation schemes, with one single snapshot. The simulation results verify the usefulness of the proposed algorithm.

Spectral line suppression capabilities of spectral line free convolutional codes in UWB over fiber systems

ABSTRACTThe topic of spectral line suppression is of major importance when designing impulse radio ultrawideband (IR‐UWB) systems. The presence of spectral lines in the power spectral density (PSD) may limit the maximum transmission power to comply with UWB regulations, thus, affecting the system performance. Although previous works have shown the advantages of IR‐UWB over fiber (UWBoF) implementations, the topic of spectral line suppression in PSD in such systems has not been entirely addressed. This letter proposes a simple IR‐UWBoF system using spectral line free (SLF) convolutional codes to address this topic. Experimental results show that the proposed system offers improved PSD characteristics compared to conventional IR‐UWBoF implementations. Furthermore, it is demonstrated that the proposed system is able to deliver SLF IR‐UWB signals over single‐mode fibers up to 30 km. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1712–1715, 2014

Time Reversal Based Timing Acquisition for Ultra-Wideband Wireless Communications: Numerical and Experimental Study

A novel timing acquisition method is proposed for ultra-wideband (UWB) wireless communications in dense multipath environments. This method is based on the time reversal technique that employs the temporally reversed channel probing waveforms rather than initial source pulses as the carrier to send the timing preambles. The temporally reversed channel probing waveforms are obtained by simply flipping the channel probing waveforms along the time axis. With the proposed method, the UWB system does not require complicated algorithms to estimate the physical channel at both transmitters and receivers and is capable of recovering the starting time of the transmitted symbols quickly with a very small number of training preamble bits. This is because the focusing properties of the time reversal technology greatly compress the time delay spread of the received preamble pulses and enhance the received pulse energy. A single-input-single-output pulsed UWB radio system is presented to demonstrate the proposed method. Both numerical and experimental results illustrate that the time reversal based timing acquisition method not only speeds up the timing acquisition, but also improves the accuracy of the timing acquisition.