Impulse Radio Ultra-wideband Systems Research Articles

An Antijamming Method Based on Multichannel Singular Spectrum Analysis and Affinity Propagation for UWB Ranging Sensors

Ultra-wideband impulse radio system has received extensive attention due to their high resolution and poor interception possibility. But the specific electromagnetic threat posed by its complex work environment cannot be ignored. In all kinds of active jamming signals, smart noise jamming plays an important role in modern radar electronic warfare, and most traditional anti-jamming methods have less suppression effect. In this paper, the mechanism of smart noise jamming on the UWB ranging sensor is discussed first. On this basis, an anti-smart noise jamming method based on multichannel singular spectrum analysis and kurtosis characteristic is proposed. Experiments show that smart noise jamming is more threatening to the UWB system than other noise modulation jamming. And the improved algorithm proposed in this paper can suppress the jamming better. After the anti-jamming processing, the average detection probability can reach more than 95%. Meanwhile, the method is improved by adding the affinity propagation (AP) clustering algorithm to solve the underdetermined signal separation problem in the case of compound jamming. The advantage is that it does not have to estimate the number of signals first. Even if the SJR is -10 dB, the waveform similarity between the separation signal and the source signal can reach 0.7 or more.

An Optimized IR-UWB Communication System with Interference Reduction on a Narrowband System Using Genetic Algorithm

This paper proposed a new impulse radio ultra wideband (IR-UWB) signal to reduce interference on narrowband systems at high usage 5.2 GHz frequency. The combination of 4th and 5th order derivatives of Gaussian pulses were employed to generate the signal so that satisfy the US Federal Communications Commission (FCC) mask. The genetic algorithm technique was used to find the pulse optimized parameters. In this paper, spectrum was optimized by changing the shape factor (sigma) and amplitude of Gaussian pulses so that the transmitted power spectrum density was minimized at a frequency of 5.2 GHz and maximized at the other frequencies from 3.1 to 10.6 GHz according to the FCC mask. The signal was applied in an IR-UWB transceiver system with binary-phase shift keying modulation. The IR-UWB waveform is generated by a programmable digital to analog based circuit. The proposed system was compared with conventional IR-UWB systems at the same condition. The simulation results in multipath channel showed that the proposed system not only reduced interference with the narrowband system, but also this was robust against narrowband interference at 5.2 GHz frequency.

3-D Gait Abnormality Detection Employing Contactless IR-UWB Sensing Phenomenon

Gait disorder diagnosis and rehabilitation is one area where human perception and observation are highly integrated. Predominantly, gait evaluation comprises technological devices for gait analysis, such as dedicated force sensors, cameras, and wearable sensor-based solutions; however, they are limited by insufficient gait parameter recognition, postprocessing, installation costs, mobility, and skin irritation issues. Thus, the proposed study concentrates on the creation of a widely deployable, noncontact and nonintrusive gait recognition method from impulse radio ultrawideband (IR-UWB) sensing phenomenon, where a standalone IR-UWB system can detect gait problems with less human intervention. A 3-D human motion model for gait identification from IR-UWB has been proposed with embracing spherical trigonometry and vector algebra to determine knee angles. Subsequently, normal and abnormal walking subjects were involved in this study. Abnormal gait subjects belong to the spastic gait category only. The prototype has been tested in both anechoic and multipath environments. The outcomes have been corroborated with a simultaneously deployed Kinect Xbox sensor and supported by a statistical graphical approach Bland and Altman (B&A) analysis.

UWB Receiver via Deep Learning in MUI and ISI Scenarios

In this paper, we consider a multiuser impulse radio ultra-wideband (UWB) system and focus on a single target user 's signal reception in the presence of multiuser interference (MUI) and/or inter-symbol interference (ISI). We propose a deep learning (DL) based receiver, which is trained off-line by simulated data to learn the joint effect of UWB pulsing, channel effect, and signal detection. Then we apply it online to recover the real-time transmitted data symbols. Numerical results demonstrate that the deep-learning based receiver can efficiently learn such joint effect in the presence of MUI and ISI, leading to much better bit error rate (BER) performance than conventional correlation receiver and other existing receivers.

Design of Reconfigurable Bandwidth Filtering Antenna and Its Applications in IR/UWB System

A reconfigurable bandwidth antenna for an impulse radio-UWB (IR/UWB) system design is illustrated in this paper. By adopting a continuously tunable low-pass filter by varactor at the feed of the antenna, the proposed antenna obtains a continuous tunable bandwidth from 1.02 GHz to 2.42 GHz. To ensure the identifiability of transmitted pulses in (IR-UWB) system, the antenna is analyzed in both frequency domain and time domain. The proposed antenna is valid with a system fidelity factor (SFF) above 0.8 while the bandwidth is tuning. The compact size, low cost, and tunable bandwidth with the identifiability of the transmitted pulse makes it suitable for UWB impulse radars to improve the utility ratio of frequency, and dynamic adjustment avoids interference of the IR-UWB in other communication frequency bands.

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.

Time Domain Performance of Reconfigurable Filter Antenna for IR-UWB, WLAN, and WiMAX Applications

A novel reconfigurable filter antenna with three ports for three dependent switchable states for impulse radio-ultrawideband (IR-UWB)/wireless local area network (WLAN)/worldwide interoperability for microwave access (WiMAX) applications is presented in this paper. Three positive-intrinsic-negative diodes, controlled by direct current, are employed to realize frequency reconfiguration of one ultra-wideband state and two narrowband states (2.4 GHz and 3.5 GHz). The time domain characteristic of the proposed antenna in the ultra-wideband state is studied, because of the features of the IR-UWB system. The time domain analysis shows that the reconfigurable filtering antenna in the wideband state performs similarly to the original UWB antenna. The compact size, low cost, and expanded reconfigurable filtering features make it suitable for IR-UWB systems that are integrated with WLAN/WiMAX communications.

Joint VMIMO and LDPC Decoders for IR-UWB Wireless Body Area Network

A complete impulse radio-ultra wide band (IR-UWB) system is proposed to mitigate the impairments concerning on-body to off-body Wireless Body Area Networks (WBAN). The proposed system maintains the practical communication link between on-body sensors to the fusion center or the monitoring device held by the medical representative. Also, these sensors are assigned a recently proposed pulse shaping to mitigate the noise that existed in the IR-UWB WBAN channel. Furthermore, virtual multiple-input multiple-output (VMIMO) is proposed to perform spatial multiplexing between various sensors transmitted data. Moreover, low complex low density parity check (LDPC) encoding/decoding algorithms, including a new low complex hybrid LDPC decoding algorithm, are proposed to reduce the complexity and to enhance the bit error rate of the on-body sensors. Interestingly, low energy consumption at every sensor participating in the on-body to off-body WBAN was achieved by adopting the combination between LDPC decoders and VMIMO technique. According to simulation results, the new system enhanced the BER performance and reduced the complexity of the on-body to off-body IR-UWB communication system effectively.

Dual Notched Band Quad-Element MIMO Antenna With Multitone Interference Suppression for IR-UWB Wireless Applications

Ultrawideband (UWB) signals are extremely power limited due to the severe power spectral density constraints obligated by the Federal Communications Committee. Therefore, the design of radiation efficient antennas for UWB signaling is a challenging step in the design and development of impulse radio UWB (IR-UWB) communication systems, especially when these signals coexist with previously standardized narrowband (NB) wireless services. In this paper, a dual-band-notched quad-element UWB multiple-input multiple-output (MIMO) antenna design is presented. The proposed design is capable of suppressing NB interference (NBI). The NBI suppression capability of the proposed design is tested both experimentally and through simulations. Moreover, the experimentally measured spectral characteristics of the proposed design are employed in simulating the bit error rate (BER) performance of IR-UWB systems, considering the biphase modulation (BPM) scheme. Both experimental and simulation results show that the proposed design is capable of improving the BER performance of BPM-modulated IR-UWB systems in an NBI environment by suppressing the NBI signals located at six different frequencies within the bandwidth of the two band notches of the proposed design, while introducing a negligible distortion to the IR-UWB signaling waveforms.

QPSK Modulation Scheme Based on Orthogonal Gaussian Pulses for IR-UWB Communication Systems

A new impulse radio-ultra wideband (IR-UWB) communication system with quadrature phase shift keying (QPSK) modulation scheme was presented in this research. The system utilized orthogonal property of fourth- and fifth-order derivatives of Gaussian pulses for modulation and time hopping (TH) multiple-access scheme. This system was compared with conventional TH-PPM and TH-BPSK systems at the same condition. The simulation results in multipath channel showed that the proposed system can provide better bit rate performance compared with the conventional IR-UWB system. A very low power and low complexity circuit for generation of the fourth-order derivative of Gaussian pulse was also proposed. The circuits of fourth- and fifth-order derivatives of Gaussian pulses were simulated using a 0.18[Formula: see text][Formula: see text]m CMOS technology. The core chip size was only 0.015[Formula: see text]mm2. The output amplitude pulse yielded 135[Formula: see text]mV peak to peak under a supply voltage of 1.8[Formula: see text]V. The energy consumption of the fourth- and fifth-order derivatives of Gaussian pulses circuits were 8[Formula: see text]pJ/pulse for 200[Formula: see text]MHz pulse-repeating frequency (PRF).

IR-UWB Sensor Network Using Massive MIMO Decision Fusion: Design and Performance Analysis

This paper proposes and analyzes impulse radio ultra-wideband (IR-UWB) system for wireless sensor networks (WSNs) using massive antenna arrays (MAAs) at fusion center (FC) for distributed detection. The coherent- and energy-based fusion rules are analyzed for the proposed WSN over multiple access channels. The tradeoff between the performance and the implementation complexity of the coherent- and energy-based fusion is studied. Furthermore, we show that MAAs at FC with various levels of channel knowledge can enhance the performance of energy-based detector in a UWB sensor network with simple system implementation and signal processing. Performance of the proposed UWB sensor network with reference to probability of detection, false alarm, and error are analyzed over the standard IEEE 802.15.4a multipath channels and results are validated using simulations. We have also analyzed the impact of various design parameters, such as the number of sensors, receiver antennas, sensor quality, and integration interval, on the system performance.

Efficient Hybrid Modulation/Demodulation Scheme Using Differential Encoding/Decoding for UWB-IR

An efficient hybrid modulation/demodulation scheme using a short duration pulse in the time-domain for ultra wideband-impulse radio (UWB-IR) systems is proposed. The proposed modulation scheme is pulse position modulation (PPM) of the UWB-IR standard modulation combined with differential encoding, and non-coherent energy detection (ED) adopting differential decoding is proposed for demodulation. Differential encoding makes a pulse that can transfer additive information bit into bits assigned in one symbol without increasing the symbol period. The BER performance is evaluated for 2-PPM, 4-PPM and the proposed HD-2PPM (which has the same symbol duration as BPPM and includes two information bits per symbol). The error performance indicates that the proposed scheme is an outstanding 0.5 dB over existing schemes of UWB-IR, and the data-rate performance shows that the proposed method has higher spectral efficiency than conventional methods that occupy the same duration as the proposed scheme.

A CMOS 6–10 GHz impulse radio UWB transmitter based on gated oscillator with switching pulse shaper

In an impulse radio ultra-wideband (IR-UWB) system for low-power location-aware sensor networks, the output pulses must meet the FCC spectral emission mask. In addition, to increase battery life, the IR-UWB transmitter must be energy efficient. In this paper, a CMOS ultra-wideband (UWB) transmitter designed using a 0.11-μm process is presented for 6–10 GHz applications. To reduce energy consumption, the transmitter adopts a gated voltage-controlled oscillator (VCO) that directly drives 50 Ω output impedance. A gated VCO that uses a trapezoidal pulse for on/off gating of the tail current source satisfies the spectrum mask without requiring an additional pulse shaping filter. The active energy consumption is 13.4 pJ/pulse at a pulse repeating frequency (PRF) of 40 MHz. The side-lobe rejection performance is more than 30 dB.

Biorthogonal PPM for Transmitted Reference IR-UWB Communication Systems

Research of impulse radio ultra-wideband (IR- UWB) systems has been extensively increasing in recent years due to their high power efficiency, high data rates and low hardware complexity. The choice of the modulation scheme used in an IR-UWB system has a great impact on its overall performances. In this paper, the biorthogonal pulse position modulation (BPPM) scheme for the application in transmitted reference (TR) IR-UWB communication systems is proposed. Performances of the BPPM scheme over two different IEEE 805.15.3a channel models in a multi-user environment are analyzed and compared to the performances of the pulse position modulation (PPM) scheme. The results show that the BPPM scheme outperforms the PPM scheme in terms of bit error rate (BER), data rate and hardware complexity. Additionally, the influence of different system parameters on the BPPM performances in TR IR-UWB systems is analyzed and possible trade-offs are proposed.

Pulse‐preserving characteristics and effective isotropically radiated power spectra of a new ultrawideband dielectric resonator antenna

A dielectric resonator antenna (DRA) with a full ground plane and an ultrawideband (UWB) operating bandwidth of 3.1–11.6 GHz is presented. Good return loss over a wide bandwidth is achieved, while the full ground plane directs most of the radiation into the upper hemisphere, significantly reducing undesirable radiation to the lower hemisphere. The measured results confirm a 10-dB return-loss bandwidth of 115%. Time-domain characteristics and effective isotropically radiated power (EIRP) spectra of the antenna are investigated for several types of UWB input pulses. The correlations between the input pulses and the radiated pulses in many directions were found to be excellent when the antenna is excited by a linearly chirped Gaussian pulse or a fifth-order Gaussian pulse. Nevertheless, EIRP spectrum calculations indicate that none of those pulses efficiently fill the Federal Communication Commission UWB mask when applied to this DRA. Hence, a third-order Rayleigh pulse is introduced and tuned to make efficient use of the allowed spectrum limits. Further improvement of pulse performance is investigated by varying antenna design parameters. This DRA is suitable for both impulse radio UWB systems and carrier-based UWB systems.

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.

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.

Joint Multiple Symbol Differential Detection and Channel Decoding for Noncoherent UWB Impulse Radio by Belief Propagation

This paper proposes a belief propagation (BP) message passing algorithm-based joint multiple symbol differential detection (MSDD) and channel decoding scheme for noncoherent differential ultra-wideband impulse radio (UWB-IR) systems. MSDD is an effective means to improving the performance of noncoherent differential UWB-IR systems. To optimize the overall detection and decoding performance, this paper proposes a novel soft-in soft-out (SISO) MSDD scheme for noncoherent differential UWB-IR. We first propose a new sampling mechanism for the noncoherent auto-correlation receiver to sample the received UWB-IR signal. The proposed sampling mechanism can exploit the dependences (imposed by the differential modulation) among data symbols throughout the whole packet. The signal probabilistic model has a hidden Markov chain structure. We use a factor graph to represent this hidden Markov chain. Then, we apply BP message passing algorithm on the factor graph to develop an SISO MSDD scheme, which is easy to integrate with SISO channel decoding to form a joint MSDD and channel decoding scheme. Performance results of bit error rate simulations and EXIT chart analyses indicate the performance advantages of our scheme over the previous MSDD scheme.