UWB Pulse Research Articles

High-order UWB pulses scheme to generate multilevel modulation formats based on incoherent optical sources

We present a high-order UWB pulses generator based on a microwave photonic filter which provides a set of positive and negative samples by using the slicing of an incoherent optical source and the phase inversion in a Mach-Zehnder modulator. The simple scalability and high reconfigurability of the system permit a better accomplishment of the FCC requirements. Moreover, the proposed scheme permits an easy adaptation to pulse amplitude modulation, bi phase modulation, pulse shape modulation and pulse position modulation. The flexibility of the scheme for being adaptable to multilevel modulation formats permits to increase the transmission bit rate by using hybrid modulation formats.

Photonic MMW-UWB Signal Generation via DPMZM-Based Frequency Up-Conversion

We propose a photonic technique for millimeter-wave ultra-wideband (MMW-UWB) signal generation via direct frequency up-conversion using a dual-parallel Mach-Zehnder modulator (DPMZM). By properly setting the dc bias voltages of the DPMZM, the baseband UWB pulse is up-converted to the MMW band without pulse distortion. In addition, the excessive residual local oscillator component is perfectly suppressed. The electrical spectrum of the up-converted UWB signal satisfies the Federal Communications Commission spectral mask very well.

Integrable high order UWB pulse photonic generator based on cross phase modulation in a SOA-MZI

We propose and experimentally demonstrate a potentially integrable optical scheme to generate high order UWB pulses. The technique is based on exploiting the cross phase modulation generated in an InGaAsP Mach-Zehnder interferometer containing integrated semiconductor optical amplifiers, and is also adaptable to different pulse modulation formats through an optical processing unit which allows to control of the amplitude, polarity and time delay of the generated taps.

FPGA based flexible UWB pulse transmitter using EM subtraction

An all-digital field programmable gate array based electromagnetic subtraction technique for direct UWB pulse generation is presented. Using this technique, it is possible to generate Gaussian pulses, monocycles or doublets with high flexibility using a single printed circuit board layout. User-controlled parameters include amplitude, pulse-width, pulse-type, repetition rate or even modulation. Measurements indicate a Gaussian pulse with 1.24 V peak amplitude and a 10% pulse-width of 670 ps can be transmitted at a repetition frequency of 100 MHz. The corresponding − 10 dB bandwidth is 2.8 GHz.

Design and Research on Optimization Combination of UWB Pulse Waveform Based on Gaussian Pulse Derived Function

This paper analyses time-domain waveform and its unilateral energy spectral density based on the Gaussian pulse former 12 derivative functions. We could conclude that pulse forming factor has a closer relationship with different order number derived function affected the energy spectral density. Therefore, in order to maximize the approximate Federal Communications Commission (FCC) emission mask as much as possible, an iterative algorithm is proposed to optimize the linear combination of the Gaussian pulse former 12 order derived function. Compared with single differential Gaussian pulse, the simulation results show that after linear combination, new ultra-wideband pulse signal could greatly meet the spectrum utilization and indoor radiation mask standards promulgated by the FCC.

Low-complexity synchronization algorithms for orthogonally modulated IR-UWB systems

Timing synchronization is a major issue for any communication system since it is essential to ensure its stable operation and reliable performance. In this paper, we compare two low-complexity synchronization algorithms for impulse radio ultra-wideband (IR-UWB) system, employing orthogonal pulse shape modulation (PSM). The two widely adopted modulation schemes for IR-UWB systems are binary pulse amplitude modulation and binary pulse position modulation. However, the possibility of generating orthogonal UWB pulses in recent years has motivated the use of orthogonal PSM which is particularly attractive as high-order modulation and also due to its possible robustness against ISI, and therefore is the focus of this paper. Relying on the unique signal format, the first algorithm applies simple overlap-add operation followed by energy detection to achieve synchronization. This approach is semi non-data-aided (NDA) because a part of the signal is specifically reserved to help enable synchronization. The other algorithm, on the other hand, exploits the discriminating nature of well-designed polarity codes and employs a series of code word matching and averaging operations to achieve synchronization. This approach is full NDA as there is no need to interrupt the data transmission. Based on the judicious change in the phase of transmitted signal applied for synchronization purposes, the second algorithm can also be used to extract synchronized aggregate templates. These templates are then used in demodulation, resulting in a low-complexity non-coherent alternative to complex Rake receivers. The two compared timing algorithms rely on simple overlap-add operations and thus remain operational under practical UWB settings. Simulation results are provided to demonstrate the efficient performance of proposed timing estimators.

Ultra Wide Band Pulse Generation Using Advanced Design System Software

In radio spectrum, Ultra Wide Band is a defined as the technology which is used for short range communication with high bandwidth at low energy dimensions. Ultra Wide Band technology find its application in radar imaging, location based services and live tracking. The Objective of this paper is to generate UWB pulse. Here UWB pulse generation is simulated using Advanced Design System software. The operation output pulse are obtained in the interval of 10usec for input pulse train of 10usec ON state and 10usec of OFF state at low inductive values of UWB generation circuit. The oscillations are neglected by connecting high inductive value in UWB pulse generation circuit. The skipped output pulses are obtained for the input pulse with rise and fall time. Short pulse UWB pulse generation is simulated using schottky diode. The short pulse of 0.2usec with oscillations is obtained for the bit sequence short input pulse of UWB pulse generation circuit.

SU‐E‐J‐62: Theoretical Investigation of Ultra‐WideBand (UWB) Penetration Through Biological Tissues

Purpose: The UWB is a radio‐frequency electromagnetic pulse with width around nanosecond encompassing 3.1–10.6 GHz frequencies. The UWB is currently used in remote sensing as through‐the‐wall imaging technology. To develop this technology into through‐the‐body tumor‐detection technology, first, we theoretically investigate whether the UWB pulses can penetrate through human tissues such as skin, muscle, bone, fat, and lung. Specifically we want to calculate which frequencies can penetrate deeper through human tissues. Methods: We theoretically relate the complex permittivity with the complex index of refraction and obtain the reflection and transmission coefficients for skin, muscle, bone, fat, and lung. We use an experimentally‐measured complex permittivity from the published source1 as input to our numerical model. We calculate 1/e penetration depth, which is equivalent to 36.7% of initial radar power, for each frequency, from air to each tissue as an indicator of penetration capability of the UWB. Results: Our results show that lower UWB frequency (3 GHz) is better at penetrating through the human tissues than higher frequency (10 GHz). We find 1/e penetration depth for human skin, muscle, fat, bone, and lung to be 4.45, 4.67, 0.49, 2.61, and 2.38 cm for 3 GHz, respectively. At 10 GHz, the 1/e penetration depths are reduced significantly to 0.17, 0.13, 0.33, 0.21, 0.19 cm, respectively. This Result indicates that it is better to design a UWB radar system with higher power at lower frequencies. Conclusion: We find that lower frequencies of the UWB can penetrate deeper into human tissues. This Result will be used to design a future experiment for further investigation of the UWB radar as a new modality for lung‐tumor detection.1. Gabriel et al. The dielectric properties of biological tissues: I. Literature survey Phys. Med. Biol. 41(11) 2231‐2249

A Synchronous Super-Regenerative Receiver for UWB Pulse Detection

A Synchronous Super-Regenerative Receiver for UWB Pulse Detection

ARTIFACT REMOVAL ALGORITHMS FOR MICROWAVE IMAGING OF THE BREAST

One of the most important components of any Confocal Microwave Imaging (CMI) system for breast cancer detection is the early-stage artifact removal algorithm. The early-stage artifact is composed of the incident pulse combined with the re∞ection from the skin-breast interface and residual antenna reverberation, and must be removed from the received signal at each antenna before further processing can take place. If the early-stage artifacts are not removed, they could potentially mask energy re∞ected from shallow tumors located close to the surface of the skin, and also hinder the identiflcation of tumors located deeper within the breast. Many existing artifact removal algorithms are based on variants of the assumption that the artifact in a particular channel can be estimated and efiectively removed by creating a reference waveform. This reference waveform is typically based on the average of the artifact in all channels. The artifact in a particular channel is then removed by subtracting this reference waveform from the recorded signal. More sophisticated algorithms estimate the artifact in each channel as a flltered combination of all the artifacts, and have been shown to be more robust to normal variations in skin thickness. However, increased underlying dielectric heterogeneity, as highlighted by Lazebnik etal., could result in greater variation in the early-stage artifact, making the artifact removal process much more di-cult. In this paper, several existing artifact removal are examined in this context of increased dielectric heterogeneity, and based on these results, suggestions for future work are presented. More than 40,000 women die annually in the United States from breast cancer, making it the leading cause of death in American women. One of the most promising alternate breast imaging modalities is microwave imaging. The physical basis for microwave imaging is the dielectric contrast between the constituent tissues of the breast and cancerous tissue at microwave frequencies. The Confocal Microwave Imaging (CMI) approach involves illuminating the breast with a UWB pulse, recording the backscattered signals and then using these signals to identify and locate signiflcant dielectric scatterers within the breast. Regions of high energy within the resultant image may suggest the presence of tumours. However, recent studies have found the breast to be dielectrically heterogeneous. Signiflcantly, Lazebnik etal. (1) found a very signiflcant dielectric contrast between normal adipose and flbroglandular tissue within the breast. Comparison studies have examined the performance of several UWB beamforming algorithms in the dielectrically heterogeneous breast. However, no previous study has compared the performance of early-stage artifact removal algo- rithms. The early-stage artifact is composed of the input signal, the re∞ection from the skin-fat interface and any antenna reverberation. This artifact is typically several orders of magnitude greater than than the re∞ections from any tumours present within the breast. If the artifact is not removed efiectively, it could easily mask tumours present within the breast. In this paper sev- eral existing artifact removal algorithms are described and compared, before suggestions for future development are presented.

On the Detection of Frequency-Spectra-Based Chipless RFID Using UWB Impulsed Interrogation

A novel approach is presented to accurately estimate the resonant features of a multipatch backscatter-based chipless radio frequency identification (RFID) tag. An ultra-wideband impulse radar (UWB-IR)-based reader interrogates the chipless tag with a UWB pulse, and the received backscatter is analyzed in the time domain. The key components constituting the backscattered signal, the structural mode, and the antenna mode are identified, and their spectral content are analyzed. Analysis shows that the antenna mode backscatter contains the information carrying signal while the structural mode backscatter contains no information about the tag. A semi-analytical model is developed to explain the behavior of the signal backscattered from the chipless RFID tag. Simulation and semi-analytical results are validated by experimental measurements obtained in an anechoic chamber environment using a 4-b multipatch chipless RFID tag. The new method does not rely on calibration tags for operation and has a greater degree of freedom in the orientation of tags with respect to a reader. A novel method, selective spectral interrogation (SSI), that uses a set of interrogation pulses to extract information bits stored in the spectral signature of the chipless tag is also introduced.

3–5 GHz 4-Channel UWB Beamforming Transmitter With 1$^{\circ}$ Scanning Resolution Through Calibrated Vernier Delay Line in 0.13-$\mu\hbox{m}$ CMOS

A 3-5 GHz 4-channel UWB beamforming transmitter with 1° scanning resolution and 135° scanning range is presented in this paper. The fine resolution is attained through Vernier delay lines capable of fine resolution down to 10 ps. Accurate path delay across channels as well as UWB pulse center frequency are achieved through the proposed ΔΣ DLL calibration technique, which speeds up the calibration by 48 times compared with a counter-based approach. A novel power spectral density calibration circuit is included to adjust the UWB pulse shape for meeting the FCC mask. Fabricated in 0.13-μm CMOS, the proposed transmitter occupies only 7.2 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The power consumption is 9.6 mW while transmitting at 80 Mbps, with each transmitter achieving 10 pJ/bit and transmitter efficiency of 7.5%. This is about ten times better than those existing UWB beamforming transmitters.

Analysis on the Anti-Interference Performance of UWB Receivers

UWB technique is widely used in radar detection system benefiting from the large bandwidth and short duration of UWB pulses. In traditional detection system, correlation receivers are usually adopted since lower SNRs are tolerated. This paper analyses the performance of anti-interference with 30dB additive noise for reference signal and 20dB additive noise for received signal as well as the pulse position shift of 100ps in UWB correlation receivers.

Performance Comparison of UWB Pulse Modulation Schemes under White Gaussian Noise Channels

In this paper, and for the first time, the performance of various ultra wideband pulse modulation schemes are discussed and compared in terms of narrowband interference robustness, symbol error rate, system complexity, data rate, and maximum transmit power with respect to transceiver distance and channel capacity. The channel model is the UWB IEEE 802.15.3a multipath indoor channel model under additive white Gaussian noise. The transmit power was evaluated by integrating the fifth derivative of the power spectrum density of the Gaussian pulse over the whole bandwidth.

Conservation of the law of phase modulation for UWB pulse signals in the first principal component

This paper considers the possibility to employ the first principal component (Kahrunen-Loeve transform) to reveal the law of reflected signal phase modulation. The processing of modeled and real signals representing ultrawideband impulses reflected from a simple target and from a model imitating human breath was taken as an example. It is experimentally shown that, for small movements of the target, the first principal component’s movement trajectory follows the original law of reflected signal phase modulation with precision of not less than 20%.

Gigabit/s Photonic Generation, Modulation, and Transmission for a Reconfigurable Impulse Radio UWB Over Fiber System

We propose and demonstrate a flexible and high-speed impulse radio ultrawideband (IR-UWB) over fiber system using various modulation schemes. Two kinds of fully Federal Communication Commission (FCC) compliant UWB pulses are produced, which is based on the incoherent summation of multiple monocycle pulses with inverse polarities, proper time delays, and different weights. Theoretically, their spectral power efficiency can achieve 33.9% and 47.4%, respectively, which is much higher than that of the conventional monocycle and doublet pulses. A good agreement between the theoretical and experimental results for the generation of designed UWB pulses is also observed. Moreover, electrically reconfigurable multiple modulation formats such as on-off keying (OOK) modulation, binary phase shift keying (BPSK) modulation, pulse shape modulation (PSM), and pulse position modulation (PPM) are implemented experimentally. Furthermore, the UWB signals with OOK, BPSK, and PPM are transmitted over a combined wired (single-mode fiber) and wireless link. The transmission performance of the newly generated UWB pulses is then evaluated by electrical spectra, eye diagrams, and bit-error-rate measurements. For all the modulation formats, a forward-error-correction (FEC)-limit error-free operation is obtained, and the power penalties of transmission are less than 1 dB.

RECONFIGURABLE FILTER ANTENNAS FOR PULSE ADAPTATION IN UWB COGNITIVE RADIO SYSTEMS

The design of fllter antennas with reconflgurable band stops is proposed. They are meant for employment in ultrawideband cognitive radio (UWB-CR) systems, where unlicensed users communi- cate using adaptive pulses that have nulls in the bands used by licensed users. Neural networks or circuits implementing the Parks-McClellan algorithm can generate such pulses. With fllter antennas, reconflg- urable bandstop fllters are flrst designed, to induce adaptive nulls in UWB pulses, and are then integrated in the feed line of a UWB an- tenna. The advantages of this combination are discussed. The fllters are based on split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs). The relationship between the SRR and CSRR parameters and the stop band is also studied.

Synchronous delay based UWB pulse generator in FPGA

This paper presents an architecture for generating UWB pulses with a high centre frequency accuracy. The architecture allows to generate frequencies twice that of the FPGA clock using synchronous delays and is implementable in all types of FPGA. With a FPGA clock of 150 MHz, we generate RF pulse of 300 MHz with a maximum fractional bandwidth of 30%. The architecture also allows pulse width increment in steps of the clock period.

Advanced Techniques and Antenna Design for Pulse Shaping in UWB Cognitive Radio

Spectrum scarcity has emerged as a primary problem in the communications technology. The combination of cognitive radio (CR) and ultra-wideband impulse radio (UWB-IR) has been proposed to solve the shortage problem by allowing smart and adaptive spectrum management, leading to UWB-CR. In a UWB-CR scheme, secondary users are supposed to ensure interference avoidance by adaptively selecting the portions of the spectrum not being used by primary users. In this paper, three different techniques for the generation of adaptive UWB pulses are studied. The Parks-McClellan algorithm is employed, a neural network is trained, and a reconfigurable band stop filter is designed to generate an adaptive waveform with nulls at specific frequencies. Simulations, measurements, and analysis show that each generated UWB pulse has remarkable advantages in the frequency utilization, spectrum avoidance, and hardware implementation.

SYNTHESIS, DESIGN AND IMPLEMENTATION OF ULTRA-WIDEBAND IMPULSE RADIO ACTIVE MMIC MATCHED FILTERS

In this paper, we present a comprehensive framework from synthesis to implementation of active matched fllters for UWB Impulse Radio. The method delays and sums UWB pulses coherently to strengthen the signal over white Gaussian noise. Theoretical analysis shows that the signal peak is maximized against noise, and an arbitrary transfer function could be realized by adjusting fllter parameters. To verify the concept, a four-stage matched fllter operating in 3{5GHz with 360 degrees phase delay is demonstrated flrst. It is implemented in a commercial 2-m GaAs HBT process and achieves a power gain of 13.8dB with a 10dB bandwidth of 1.3GHz. Based on a similar architecture, another design is presented but with only half of the delay. It has a power gain of 15.9dB and a 10dB bandwidth of 2.3GHz. An advantage of the proposed method is a precise control of the impulse response that can be matched to either symmetrical or asymmetrical UWB pulses by taking a time domain design approach.