Impulse Radio Research Articles

Acquisition Performance of a BDS Receiver with UWB Impulse Radio Interference

Acquisition Performance of a BDS Receiver with UWB Impulse Radio Interference

A Pilot Study of Impulse Radio Ultra Wideband Radar Technology as a New Tool for Sleep Assessment.

To validate Impulse radio ultra wideband pulse-doppler radar technology against polysomnography (PSG) for sleep assessment. In all, 12 participants were recruited and their overnight sleep was assessed both by a Novelda XeThru radar and PSG. Two subjects had two nightly recordings, whereas 10 had one recording. Epoch by epoch (30 seconds) comparisons from bedtime to rise time were conducted. Concordance was estimated in terms of the mean difference between the radar and the PSG estimates regarding sleep onset latency, wake time after sleep onset and total sleep time. In addition, accuracy, sensitivity, specificity and Cohen kappa were calculated. The mean difference (minutes) between the radar and the PSG registrations was -5.7 minutes (standard deviation [SD] = 22.1 minutes) for sleep onset latency, 6.4 minutes (SD = 32.5 minutes) for wake after sleep onset, and 1.5 minutes (SD = 24.6 minutes) for total sleep time. The mean values obtained for accuracy, sensitivity, specificity and Cohen kappa were 0.931, 0.961, 0.695 and 0.670, respectively. Impulse radio ultra wideband radar technology is a promising tool in terms of affordable and practical objective sleep assessment. Further technical development and more validation studies are needed in order to conclude about the utility potential of this device.

Impulsive radio and hard X-ray emission from an M-class flare

Context. Impulsive radio and hard X-ray emission from large solar flares are usually attributed to a hard distribution of high-energy electrons accelerated in the energy dissipation process of magnetic reconnection. Aims. We report the detection of impulsive radio and hard X-ray emissions produced by a population of energetic electrons with a very soft distribution in an M-class flare: SOL2015-08-27T05:45 . Methods. The absence of impulsive emission at 34 GHz and hard X-ray emission above 50 keV and the presence of distinct impulsive emission at 17 GHz and lower frequencies and in the 25–50 keV X-ray band imply a very soft distribution of energetic electrons producing the impulsive radio emission via the gyro-synchrotron process, and impulsive X-rays via bremsstrahlung. Results. The spectrum of the impulsive hard X-ray emission can be fitted equally well with a power-law model with an index of ∼6.5 or a super-hot thermal model with a temperature as high as 100 MK. Imaging observations in the extreme-UV and X-ray bands and extrapolation of the magnetic field structure using a nonlinear force-free model show that energetic electrons trapped in coronal loops are responsible for these impulsive emissions. Conclusions. Since the index of the power-law model is nearly constant during the impulsive phase, the power-law distribution or the super-hot component should be produced by a bulk energization process such as the Fermi and betatron acceleration of collapsing magnetic loops.

A IR UWB Timed-Array Radar Based on 16-Channel Transmitter and Sampling Capacitor Reused Receiver

A ${4\times 4}$ impulse radio (IR) ultra-wide band (UWB) timed-array radar is proposed in this brief based on 16-channel all-digital transmitter and sampling capacitor reused receiver. 3-D beamforming is achieved by the 16-channel ( ${4\times 4}$ ) planar low power IR UWB beamforming transmitter. UWB receiver adopts energy detection and reuses the integrating capacitor as C-DAC within an 8-bit SAR ADC to save area and power consumption. Fabricated in 65-nm CMOS technology, the whole UWB radar occupies an active core area of 4.2 mm $^{{2}}$ . Delay range of 1.2 ns with 10 ps resolution is achieved, corresponding to 90° radar scanning range with 3° resolution when the ${4\times 4}$ planar array antenna spacing is 6 cm.

Sensor Radar for Object Tracking

Precise localization and tracking of moving objects is of great interest for a variety of emerging applications including the Internet-of-Things (IoT). The localization and tracking tasks are challenging in harsh wireless environments, such as indoor ones, especially when objects are not equipped with dedicated tags (noncollaborative). The problem of detecting, localizing, and tracking noncollaborative objects within a limited area has often been undertaken by exploiting a network of radio sensors, scanning the zone of interest through wideband radio signals to create a radio image of the objects. This paper presents a sensor network for radio imaging (sensor radar) along with all of the signal processing steps necessary to achieve highaccuracy objects tracking in harsh propagation environments. The described sensor radar is based on the impulse radio (IR) ultrawideband (UWB) technology, entailing the transmission of very short duration pulses. Experimental results with actual UWB signals in indoor environments confirm the sensor radar’s potential in IoT applications.

Pulse-level beam-switching for terahertz networks

Communication in Terahertz (THz) band is envisioned as a promising technology to meet the ever-growing data rate demand, and to enable new applications in both nano-scale and macro-scale wireless paradigms. In this study, we propose the first system-level design that is suitable for THz communication in macro-scale range with 100+ Gbps data rate. The design is based on the proposed terahertz pulse-level beam-switching with energy control (TRPLE), and motivated by the rise in Graphene-based electronics, which include not only compact generator and detector for pulse communication, but also the capability of beam scanning aided with nano-antenna-arrays. The very high path loss seen in THz wireless channel requires the use of narrow beam to reach longer transmission ranges. On the other hand, impulse radio that emits femtosecond-long pulses allows the beam direction to steer at pulse-level, rather than at packet-level. For TRPLE, we mathematically analyze the data rate for an arbitrary wireless link under the THz channel characteristics and the energy modulation scheme. Then, a novel optimization model is formulated to solve the parameters of the inter-pulse separation and the inter-symbol separation, in order to maximize the data rate while meeting the interference requirement. With the optimization, the data rate of 167 Gbps is shown achievable for most users in 20-m range. A MAC protocol framework is then presented to harness the benefits of the pulse separation optimization.

Improved quantisation mechanisms in impulse radio ultra wideband systems based on compressed sensing

To reduce the impact of quantisation noise during low-rate sampling of Impulse Radio Ultra-Wideband (IR-UWB) under compressed sensing framework and also considering the equal information carrying of compressed measurements and characteristics of Gaussian distribution, three modified quantisation mechanisms are designed in this study: overload uniform quantisation, non-uniform quantisation, and overload non-uniform quantisation. Also, the influencing elements of overload factor in overload mechanism are mentioned to obtain the optimisation scheme close to the optimal overload by fitting. The simulation results show that all the three modified mechanisms, especially the overload non-uniform quantisation mechanism, have wrought great improvement in performance when compared to the uniform quantisation. What's more, the performance of the overload uniform quantisation mechanism featured with low complexity is better than that of the non-uniform quantisation mechanism with high complexity, thus providing a practical quantisation method for the IR-UWB system under the compressed sensing framework.

Improved quantisation mechanisms in impulse radio ultra wideband systems based on compressed sensing

To reduce the impact of quantisation noise during low-rate sampling of Impulse Radio Ultra-Wideband (IR-UWB) under compressed sensing framework and also considering the equal information carrying of compressed measurements and characteristics of Gaussian distribution, three modified quantisation mechanisms are designed in this study: overload uniform quantisation, non-uniform quantisation, and overload non-uniform quantisation. Also, the influencing elements of overload factor in overload mechanism are mentioned to obtain the optimisation scheme close to the optimal overload by fitting. The simulation results show that all the three modified mechanisms, especially the overload non-uniform quantisation mechanism, have wrought great improvement in performance when compared to the uniform quantisation. What's more, the performance of the overload uniform quantisation mechanism featured with low complexity is better than that of the non-uniform quantisation mechanism with high complexity, thus providing a practical quantisation method for the IR-UWB system under the compressed sensing framework.

A Simple Guide to Low-Power Wireless Technologies: Balancing the Tradeoffs for the Internet of Things and Medical Applications

In recent years, low-power radio has expanded to encompass a broad range of wireless technologies, architectures, standards, and applications. The Internet of Things (IoT) and implantable electronics have multiplied the use cases for standard commercial architectures, such as ZigBee, Bluetooth, and near-field communication (NFC), while also opening the door for more exploratory radio architectures like duty-cycled wake-up radio systems, ultranarrow-band radios, and ultrawideband (UWB) impulse radios (IRs), to name just a few.

Performance evaluation of IR-UWB detectors and fusion techniques for UWB transceiver platforms

In this paper, we analyse the performance of a multi-pulse impulse radio based ultra-wideband (IR-UWB) detector in an AWGN setting and provide different fusion strategies for fusing these detector outputs. To enable the transceiver to be used for multiple applications, the designers have different types of detectors such as energy detectors, amplitude detectors, etc., built in to a single transceiver architecture. In this paper, we derive the detection performance equation for commonly used detectors in terms of false alarm rate, shape of the pulse, and number of UWB pulses used in the detection and apply these in the fusion algorithms. We show that the performance can be improved by approximately 4 dB in terms of signal to noise ratio (SNR) for high probability of detection of a UWB signal (95%), by fusing decisions from multiple detector types compared to a standalone energy detector, in a practical scenario.

Improving PSD of PPM-IR for UWB Signal Using Turbo Encoder

The repression of the spectral line is a matter of main attention in designing of Time Hopping Impulse Radio (TH-IR) Ultra-Wide Band (UWB) systems. This case has been usually processed by randomizing the locations of every pulse. This requires to employ of very long Pseudo Noise (PN) sequences to suppress the capabilities of spectral lines. This research aims to improve the Power Spectral Density (PSD) by constructing the proposed system using Turbo code technique inside MATLAB’s Simulink. We found that our proposed system provides high performance than Conventional PPM-TH-IR in term of eliminating the spectral lines or make it smoother. We also found that the increasing in interleaver length and constraint length enhances PSD.

Certificateless Scheme Based NTRU Cryptosystem for Ad-Hoc UWB-IR Network

From the radar and military research world’s, the Ultra-WideBand Impulse Radio (UWB-IR) was adopted in the telecommunications world in the 1990’. Currently, the UWB-IR technology is an interesting candidate for close range Wireless Sensors Networks (WSNs). It is particularly attractive for industrial sensor networks due to its resilience to multipath interference, simple transceiver circuitry, accurate ranging ability, and low transmission power. In order to secure data and communications in the Ad-Hoc UWB-IR networks, UWB-IR requires suitable encryption protocols. In this paper, we review and summarize the IEEE 802.15.4 security sub-layer protocol of UWB-IR based Symmetric Key Cryptography scheme. Then, we highlight the different vulnerabilities and weaknesses present in this type of scheme. Finally, we prove, after a deep examination of multiple Public Key Cryptography (PKC) schemes, that the certificateless one is the most suitable for Ad-Hoc UWB-IR networks characterized by nodes mobility. Indeed, we have also evaluated and analyzed the different public key cryptosystems (PKCS) and concluded that NTRU is the most optimum public key cryptosystem to be used with the certificateless scheme in order to secure data and communications in Ad-Hoc UWB-IR Networks. This is due to the fact that it is the fastest PKCS to provide different security levels at a high speed with very constrained resources.

A novel time of arrival estimation algorithm using an energy detector receiver in MMW systems

This paper presents a new time of arrival (TOA) estimation technique using an improved energy detection (ED) receiver based on the empirical mode decomposition (EMD) in an impulse radio (IR) 60 GHz millimeter wave (MMW) system. A threshold is employed via analyzing the characteristics of the received energy values with an extreme learning machine (ELM). The effect of the channel and integration period on the TOA estimation is evaluated. Several well-known ED-based TOA algorithms are used to compare with the proposed technique. It is shown that this ELM-based technique has lower TOA estimation error compared to other approaches and provides robust performance with the IEEE 802.15.3c channel models.

Impulse Radio Ultra-Wideband Communications for Localization and Tracking of Human Body and Limbs Movement for Healthcare Applications

Accurate and precise motion tracking of limbs and human subjects has technological importance in various healthcare applications. The use of impulse radio-ultra wideband technology (IR-UWB) technology due its inherent properties is of recent interest for high-accuracy localization. This paper presents experimental investigations and analysis of indoor human body localization and tracking of limb movements in 3-D based on IR-UWB technology using compact and cost-effective body-worn antennas. The body-centric wireless channel characterization has been analyzed in detail using parameters such as path loss magnitude, number of multipath components, rms delay spread, signal amplitude, and Kurtosis with the main focus to differentiate between line-of-sight (LOS) and non-LOS situations. Fidelity of the received signal is also calculated for different activities and antenna positions to study the pulse preserving nature of the UWB antenna, when it is placed on the human body. The results reported in this paper have high localization accuracy with 90% in the range from 0.5 to 2.5 cm using simple and cost-effective techniques which is comparable to the results obtained by the standard optical motion capture system.

Cluster-head based feedback for simplified time reversal prefiltering in ultra-wideband systems

Time-reversal prefiltering (TRP) technique for impulse radio (IR) ultra wide-band (UWB) systems requires a large amount of feedback to transmit the channel impulse response from the receiver to the transmitter. In this paper, we propose a new feedback design based on vector quantization. We use a machine learning algorithm to cluster the estimated channels into several groups and to select the channel cluster heads (CCHs) for feedback. In particular, CCHs and their labels are recorded at both side of the UWB transceivers and the label of the most similar CCH to the estimated channel is fed back to the transmitter. Finally, the TRP is applied using the feedback CCH. The proposed digital feedback provides three main advantages: (1) it significantly reduces the dedicated bandwidth required for feedback; (2) it considerably improves the speed of transceivers; and, (3) it is robust to noise in the feedback channel since few bytes are required to send the codes that can be heavily error protected. Numerical results on standard UWB channel models are discussed, showing the advantage of the proposed solution.

Energy Consumption Models For MISO-UWB and TR-MISO-UWB Systems

Abstractthis paper, an energy consumption model is developed and exploited to evaluate the electrical energy consumption of ultra-wideband impulse radio (UWB-IR) systems. We develop the energy consumption models and our comparative study, on the one hand, for a system based single-input singleoutput (SISO) configuration and a multiple-input single-output (MISO) and, on the other hand, for a time reversal TR-MISO configuration and for MISO alone configuration. We consider an indoor propagation environment based on the 802.15.4a channel model. The results show very different behaviors depending on the propagation conditions, the number of antennas used, or on the number of transmitted symbols. Using such a model, a radiofrequency designer can obtain significant inputs to optimally select an adequate configuration to design an adaptive energyaware UWB-IR system.

Use of UWB Impulse Radio Technology in In-Car Communications: Power Limits and Optimization

In-car wireless data communications systems require a short-range unlicensed radio communications technology that causes a very low level of interference in the other, already deployed radio links and networks, offers low and medium data rate, can reuse the already occupied radio-frequency (RF) bands, and assures low probability of message collisions. Ultrawide band (UWB) impulse radio employs RF pulses with very short duration to carry the information; consequently, it is an optimal candidate for the in-car wireless communications and intravehicular wireless sensor networks. Data rate and shape of RF carrier pulse determine the performance of a UWB radio link. To limit the interference caused, the maximum power radiated by an UWB device is restricted by the Federal Communications Commission (FCC) in the U.S. Introducing a new mathematical model and starting from the FCC regulations, analytical expressions for the calculation of FCC power limits are derived here. It is shown that the low- and high-rate UWB impulse radio systems are peak and average power limited, respectively. The relationship between the mathematical model and the parameters of an UWB carrier pulse used in a built UWB radio is established. The performances of RF carrier pulses known from the literature are evaluated and compared. All expressions derived are verified by measurements.

Delta–Sigma Encoder for Low-Power Wireless Bio-Sensors Using Ultrawideband Impulse Radio

This brief presents a systematic method to reduce the power consumption of a wireless sensor node for sensing biomedical signals. The design combines the delta–sigma modulator (DSM), the ultrawideband impulse radio (UWB-IR), and the proposed xnor -delay-based encoder/decoder, which replaces the decimation filter. The encoder and decoder for both the first- and second-order DSMs are presented. The clock synchronization problem is solved by using an asynchronous UWB-IR. The effects of window length, the order of delta–sigma modulation, and the oversampling ratio are studied by simulation using neural and electrocardiography signals. Based on the simulation results, the proposed method can save power by 50% compared to the system with decimation filters, and 53% compared to the system without the proposed encoder.

Windowing UWB microwave, mm‐wave multi‐port S‐parameter measurements using open‐ended excess electrical length

Multi-port measurements are a big challenge in circuits' verification, especially when the frequency increases. This study presents a new technique for measuring S-parameters of multi-port ultra-wideband (UWB) microwave and mm-wave circuits. The concepts are based on direct or indirect applying modulated UWB impulse radio in desired bandwidth to the one port of the modified multi-port circuit and gathering the reflected signal in the same port and the output signal in the second port in time domain, and the other ports are left opened with a special designed added electrical length. Then by applying intelligent windowing in time domain to the gathering data, and using fast Fourier transform, the desired S-parameters are extracted. Validation of this technique is verified by design and fabrication of a three-port UWB Wilkinson power divider in 22–30 GHz. The simulation and measurement results of the reflection and transmission S-parameters by using this new technique are very close to those are extracted with the conventional vector network analysers S-parameters measurements and show the ability and the accuracy of this technique.

Integrated Asynchronous Ultrawideband Impulse Radio With Intrinsic Clock and Data Recovery

This letter reports an integrated ultrawideband impulse radio design. The proposed radio applies a combination of frequency-shift keying and ON–OFF keying to realize intrinsic clock and data recovery as well as asynchronous wireless communication. The transmitter uses frequency-hopping and duty-cycling methods to achieve ultrawide bandwidth. Both of the transmitter and the receiver are fabricated on IBM 0.18- $\mu \text{m}$ CMOS process. The chip core area is 0.031 mm2 for the transmitter and 0.017 mm2 for the receiver. The measured power consumption is 2.89mW for the transmitter and 5.4mW for the receiver at the data rate of 3Mb/s. The sensitivity at $1.3\times 10^{-3}$ bit error rate, 2.5Mb/s, and 10.42-ns pulsewidth is −60dBm.