Ultra-wideband Systems Research Articles

A combining technique based on channel shortening equalisation for ultra wideband cooperative systems

This paper presents a novel combining technique based on the channel shortening approach for cooperative diversity in the context of time hopping ultra wideband (TH-UWB) systems. Since UWB channel has very long impulse response, TH-UWB performances are affected by inter-symbol interference (ISI). Therefore, the use of the rake diversity combining is very effective, but it increases the receiver complexity due to its large number of correlations. The idea is to introduce a channel shortening equaliser (CSE) before the rake reception in first and second time slots at the relay and destination, respectively. The decode and forward (DF) is used as a relay protocol to retransmit signals and the relay is supposed equipped with multiple antennas and antenna selection criterion is used to exploit the diversity. Numerical results show that significant improvement in the BER is obtained by our proposed structure comparing to cases where the relay is equipped with a single antenna and multiple antennas (full diversity).

Two-Dimensional $Z$-Complementary Array Code Sets Based on Matrices of Generating Polynomials

The unprecedented elevation of wireless technologies produces the ever-increasing requirement for higher-dimensional array sets with preferable correlation properties and more flexible parameters. In this paper, we investigate new two-dimensional $Z$ -complementary array code sets (2D-ZCACSs) with unimodular arrays, which are more preferable in ultra wideband communication system to improve its performance than 2D mutually orthogonal complementary array set. We first introduce a new idea of 2D $Z$ -paraunitary (2D-ZPU) matrices by extending our previous concept of 1D-ZPU matrices. Then, we show that there exists an equivalence between a 2D-ZCACS and 2D-ZPU matrix when the former is expressed as a matrix with 2D generating polynomial entries. In the 2D generating matrix, each column corresponds to a 2D $Z$ -complementary array code and two distinct columns correspond to 2D $Z$ -complementary array mates. Finally, we propose a new construction method of unimodular 2D-ZCACSs with the aid of higher-dimensional $z$ -transforms and the theory of ZPU matrices.

Enhancing the Bitrate and Power Spectral Density of PPM TH-IR UWB Signals using a Sub-Slot Technique

Increasing the receiver’s bitrate and suppressing the spectral line are issues of major interest in the design of compliant Time-Hopping Impulse Radio (TH-IR) Ultra-Wide Band (UWB) systems. Suppression of spectral lines has been commonly addressed by randomizing the position of each pulse to make the period as large as possible. Our analysis suggests that this influences the overall shape of a signal’s Power Spectral Density (PSD) in a way that is useful for spectral line suppression or diminishing the PSD maximum peak power. A method for utilizing the system to generate a Dynamic-Location Pulse-Position Modulated (DLPPM) signal for transmission across a UWB communications channel is presented, and an analytical derivation of the PSD of a proposed DLPPM signal TH-IR UWB is introduced. Our proposed method can be applied without affecting the users of other concurrent applications. The theoretical model for DPLM TH-IR is compared with the PSD for conventional DPLM TH-IR. The results show that spectral estimation methods based on Fast Fourier Transform (FFT) significantly overestimate the continuous part of the PSD for small and medium signal lengths, which has implications for assessing interference margins by means of simulation. Another purpose of this paper is to improve a predesigned system by increasing the receiver’s bitrate. This will be achieved by using the bits that control the sub-slot technique as information and designing a receiver capable of detecting them. The bitrate is effectively doubled. Finally, the proposed system for DPLM TH-IR has been built inside Simulink/MATLAB to test its results via a conventional DPLM TH-IR system.

A FPGA implementation of GMM MUD algorithm for space formation aircraft communication system

Space formation aircraft communication system needs to meet strong anti-interference ability, low power consumption and high transmission rate performance. Ultra-wideband (UWB) has high data transfer rate, low device complexity, high interference resistance and confidentiality. Therefore, UWB technology is used in space formation aircraft communication system, which is direct sequence ultra-wideband (DS-UWB) space formation aircraft communication system. This paper, we put forward a multi-user detection (MUD) algorithm based on Gaussian Mixture Model (GMM) in DS-UWB communication system and its field-programmable gate array (FPGA) implementation. We adopt a way which based on MATLAB and FPGA platform, and results show that MUD algorithm based on GMM has better bit error rate (BER) performance compared to classical multi-user detection algorithm.

ULTRAWIDEBAND ANTENNA IN WIRELESS COMMUNICATION: A REVIEW AND CURRENT STATE OF THE ART

Ultrawideband (UWB) systems offer a unique solution to attain high-speed short-range wireless communication and high precision location applications. Designing an UWB antenna with optimal characteristics is a major challenge because it needs to cover broader bandwidth, stable gain, good time-domain characteristics, and impedance matching over operational bandwidth. From the last decade, UWB technology is one of the key components of the research area and a lot of UWB antennas are designed and developed. The proposed paper highlights the promising applications and design challenges associated with the UWB antenna. It narrates the implications in developing planar UWB antenna and fine-tuning its parameters. The challenges, future perspective and wide range of UWB antenna applications are also discussed in this paper to make it useful for further research

Compact reconfigurable triple notch ultra-wideband bandpass filter for cognitive radio system

This paper introduces a compact ultra-wideband (UWB) bandpass filter (BPF) with two switchable external notch structures which avoids the interference between the UWB communication with worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN) systems, suitable for cognitive radio (CR) applications. The first external notch structure is modified C-shaped structure which generates a sharp rejection at 3.5 GHz to avoid interference with WiMAX system and second external notch structure is back to back T-shaped structure which creates sharp rejection notch bands at 5.2 GHz and 5.8 GHz frequencies for WLAN systems. The filter reconfiguration is achieved by varying the conductance of microstrip line. The response of the proposed structure shows sharp rejections at one WiMAX and two WLAN bands. The bandpass filter covers frequency of UWB system from 3.1 to 10.7 GHz having very low passband insertion loss. The proposed UWB BPF is designed, simulated, fabricated and tested to validate the results. A good agreement is achieved between simulation and experimental results.

Compact reconfigurable triple notch ultra-wideband bandpass filter for cognitive radio system

This paper introduces a compact ultra-wideband (UWB) bandpass filter (BPF) with two switchable external notch structures which avoids the interference between the UWB communication with worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN) systems, suitable for cognitive radio (CR) applications. The first external notch structure is modified C-shaped structure which generates a sharp rejection at 3.5 GHz to avoid interference with WiMAX system and second external notch structure is back to back T-shaped structure which creates sharp rejection notch bands at 5.2 GHz and 5.8 GHz frequencies for WLAN systems. The filter reconfiguration is achieved by varying the conductance of microstrip line. The response of the proposed structure shows sharp rejections at one WiMAX and two WLAN bands. The bandpass filter covers frequency of UWB system from 3.1 to 10.7 GHz having very low passband insertion loss. The proposed UWB BPF is designed, simulated, fabricated and tested to validate the results. A good agreement is achieved between simulation and experimental results.

A 3D Ray Launching Time-Frequency Channel Modeling Approach for UWB Ranging Applications

Ultrawideband (UWB) has the ability to achieve decimetre level of ranging accuracy, hence, its wider usage nowadays in the field of positioning. In spite of the attractiveness of UWB, its performance is strongly dependent on the propagation channel. In this paper, an analysis of the the UWB channel for ranging applications using an inhouse developed 3D Ray launching (3D RL) algorithm is presented. A parametric study has been performed considering variations of cuboid size resolution of the simulation mesh, in order to analyze convergence impact on estimation accuracy, focusing on Radio frequency (RF) power levels as well as time domain characterization. The RF power results have been used to model the path-loss, small scale fading, and the power delay profile so as to obtain the statistics of the multipath channel as well as time of flight (TOF) estimation values. The results show that the 3D RL is a valuable tool to test UWB systems for ranging applications with a mean accuracy of up to 10 cm in multipath conditions considering complex scatterer distributions within the complete volume of the scenarios under test.

Design of Notched Rounded Bowtie Antenna for Ultra-Wideband Communication Systems

In this paper, a modified bowtie antenna structure is proposed for Ultra-Wideband communication systems. This antenna is obtained by rounding and notching the edges of antenna arms. Antenna parameters for the designed structure are examined according to the restrictions specified by Federal Communications Commission. Thus, Return Loss (S11), Voltage Standing Wave Ratio (VSWR), gain, radiation pattern and impedance are observed in the 3.1 GHz - 10.6 GHz frequency range. Additionally, the effect of arm length and dielectric material on antenna performance are interpreted in the same range.According to obtained results, the proposed structure satisfies the bandwidth requirements for Ultra-Wideband systems. Gain and impedance variations are also in acceptable limits for Ultra-Wideband applications. The proposed antenna is analyzed through CST Microwave Studio program.

Performance of the Connection Budget of a Wireless Communication Network in Ultra Wideband Systems

Performance of the Connection Budget of a Wireless Communication Network in Ultra Wideband Systems

Impact of Body Wearable Sensor Positions on UWB Ranging

In recent years, Ultrawideband (UWB) has become a very popular technology for time of flight (TOF) based localization and tracking applications but its human body interactions have not been studied yet extensively. Most UWB systems already proposed for pedestrian ranging have only been individually evaluated for a particular wearable sensor position. It is observed that wearable sensors mounted on or close to the human body can raise line-of-sight (LOS), quasi-line-of-sight (QLOS), and non-line-of-sight (NLOS) scenarios leading to significant ranging errors depending on the relative heading angle (RHA) between the pedestrian, wearable sensor, and anchors. In this paper, it is presented that not only does the ranging error depend on the RHA, but on the position of the wearable sensors on the pedestrian. Seven wearable sensor locations namely, fore-head, hand, chest, wrist, arm, thigh and ankle are evaluated and a fair comparison is made through extensive measurements and experiments in a multipath environment. Using the direction in which the pedestrian is facing, the RHA between the pedestrian, wearable sensor, and anchors is computed. For each wearable sensor location, an UWB ranging error model with respect to the human body shadowing effect is proposed. A final conclusion is drawn that among the aforementioned wearable locations, the fore-head provides the best range estimate because it is able to set low mean range errors of about 20 cm in multipath conditions. The fore-head’s performance is followed by the hand, wrist, ankle, arm, thigh, and chest in that order.

Uwb Bpf using Quad Section Stepped Impedance Resonator

Ultra wide band (UWB) frequency range is from 3.1 to 10.6 GHz with a bandwidth of 7.5 GHz. UWB bandpass filter(BPF) is an essential component of any UWB communication system. Design of UWB BPF with extremely high bandwidth is a challenge task. In this paper a simple method is developed for the design of UWB BPF. A quad section stepped impedance resonator (QSSIR) is used as the basic element of the filter. QSSIR has four impedance sections connected in cascade. Ultra wide bandwidth is realized by appropriately selecting impedance ratio and electrical length ratio of the SIR. Two transmission zeros are introduced in the insertion loss response by folding the QSSIR. Designed filter has bandwidth extending from 3.73 to 9.93 GHz with a fractional band width (FBW) of 91% and center frequency 6.83 GHz. There are five transmission poles in the obtained frequency response. Simulation is performed using ANSOFT HFSS. Designed filter was fabricated using FR4 substrate. Test results are found to be in good agreement with simulations. Proposed filter has a simple planar structure. Fabrication is easy. It can be used in UWB systems as band pass filter

Static and Dynamic Evaluation of an UWB Localization System for Industrial Applications

Many applications in the context of Industry 4.0 require precise localization. However, indoor localization remains an open problem, especially in complex environments such as industrial environments. In recent years, we have seen the emergence of Ultra WideBand (UWB) localization systems. The aim of this article is to evaluate the performance of a UWB system to estimate the position of a person moving in an indoor environment. To do so, we implemented an experimental protocol to evaluate the accuracy of the UWB system both statically and dynamically. The UWB system is compared to a ground truth obtained by a motion capture system with a millimetric accuracy.

A 2.99 dB NF 15.6 dB Gain 3-10GHz Ultra-wideband low-noise amplifier for UWB systems in 65 nm CMOS

A low noise figure (NF) and high power gain (S21) 3–10 GHz ultra-wideband (UWB) low noise amplifier (LNA) in 65 nm CMOS technology is proposed for UWB system which has a high figure of merit. A shunt–shunt resistive feedback technique is used to achieve wideband input impedance matching. A differential current-reused structure is used to achieve high common noise suppression and low power consumption. The implemented LNA achieves a high and flat aS21 of 15.6 ± 1.07 dB with an input return loss (S11) which is better than − 8.7 dB and a low NF of 2.99 ± 0.18 dB at frequencies of 3–10 GHz. The measured input third-order intermodulation point (IIP3) is − 5.7 dBm at 6 GHz.

103 nm Ultra-Wideband Hybrid Raman/SOA Transmission Over 3 × 100 km SSMF

We report on the ultra-wideband (UWB) transmission of a 103 nm signal over 3 × 100 km of standard single mode fiber (SSMF), a widely-deployed fiber in terrestrial transmission networks. In such UWB systems, nonlinear effects such as stimulated Raman scattering (SRS) must be taken into account in the system design. We characterize the SRS impact in high power regime for this UWB spectrum. We study the evolution of SRS over the bandwidth when tilting the input spectrum to counter the inter-band power transition. We transmit 254 probabilistically constellation shaped (PCS)-64QAM channels over 300 km of SSMF and demonstrate a 107-Tb/s transmission throughput over a continuous 103 nm optical bandwidth using backward Raman pumping and SOA technology.

Novel EBG Structure BPF for UWB system

This paper discuses about application of Electro Magnetic Band-gap structure(EBG) application in design of microstrip band bass filter(BPF) in ultra wide band(UWB) frequency. Here to obtain improved pass-band region and good out of band region a single Electro Magnetic Band-gap structure (EBG) cell is used. The simulation of the filter is done using advanced design system software (ADS), the obtained result is satisfactory .in addition to the performance of the filter the size of overall filter is reduced in size which can be used in many compact handheld devices. [19],[20],[21]

Avoidance of narrowband interference in UWB wireless sensor device using square low technology

Impulse radio ultra-wideband system has been adopted in wireless sensor networks research due to its high performance in conditions of active influence of various noises and interferences, the presence of reflections, etc. In this paper, this system represents a transmitter based on the controller STM32 and a receiver implemented using blocks of analog and digital processing based on FPGA. This paper focuses on a realisation of an additional device that can provide the avoidance of narrowband interference in ultra-wideband wireless sensor network system to improve a value of bit error rate. For this purpose, a real device with using square low technique has been developed. According to the results of experiments this approach enables to improve a dependence of the bit error rate on the signal-to-noise ratio.

An Extensible Positioning System for Locating Mobile Robots in Unfamiliar Environments.

In this paper, an extensible positioning system for mobile robots is proposed. The system includes a stereo camera module, inertial measurement unit (IMU) and an ultra-wideband (UWB) network which includes five anchors, one of which is with the unknown position. The anchors in the positioning system are without requirements of communication between UWB anchors and without requirements of clock synchronization of the anchors. By locating the mobile robot using the original system, and then estimating the position of a new anchor using the ranging between the mobile robot and the new anchor, the system can be extended after adding the new anchor into the original system. In an unfamiliar environment (such as fire and other rescue sites), it is able to locate the mobile robot after extending itself. To add the new anchor into the positioning system, a recursive least squares (RLS) approach is used to estimate the position of the new anchor. A maximum correntropy Kalman filter (MCKF) which is based on the maximum correntropy criterion (MCC) is used to fuse data from the UWB network and IMU. The initial attitude of the mobile robot relative to the navigation frame is calculated though comparing position vectors given by a visual simultaneous localization and mapping (SLAM) system and the UWB system respectively. As shown in the experiment section, the root mean square error (RMSE) of the positioning result given by the proposed positioning system with all anchors is 0.130 m. In the unfamiliar environment, the RMSE is 0.131 m which is close to the RMSE (0.137 m) given by the original system with a difference of 0.006 m. Besides, the RMSE based on Euler distance of the new anchor is 0.061 m.

Closed-Form Analysis of Various Diversity Techniques for Multiband OFDM UWB System Over Log-Normal Fading Channels

In this paper, we investigate the effect of multipath fading on the combined signal-to-noise ratio (SNR) in conjunction with multiband orthogonal frequency division multiplexing ultra-wideband system with different diversity schemes such as maximal ratio combining, equal gain combining and selection combining. In particular, we derived the probability density function of the combiner output SNR followed by performance measures, average combined SNR, outage probability and average bit error rate, in the case of L-fold log-normal fading channels. The derived mathematical expressions are illustrated by applying the method to some selected numerical examples of interest showing the impact of fading variance as-well-as a number of diversity paths, which is combined, on the performance metrics of combiner output for above diversity techniques. The results show that the number of diversity paths significantly improve the effect of multipath fading on derived performance measures.

Electromagnetic modeling of an active integrated antenna with a MESFET device using MoM-GEC method for UWB applications

This paper presents electromagnetic modeling of an active integrated antenna (AIA) with a MESFET device, located inside an infinite rectangular waveguide. This work highlights the influence of the active device in the antenna performance for Ultra Wide Band (UWB) systems. In fact, the method of Moments (MoM) combined with the generalized equivalent circuits (GEC) approach in conjunction with the physical-based small-signal model is applied to compute the input impedance, the reflection coefficient, the current density and the electric field distributions of the AIA resonating at 4 GHz. The physical-based small-signal model was employed to characterize the active device. For validation purpose, the calculated results are compared to the simulated ones on the ADS Agilent simulator. Using S11 < −10 dB technique, it was found that the antenna bandwidth is superior to 500 MHz. In this sense, the collective gain is therefore investigated and calculated for the entire AIA.