Showing papers on "Continuous phase modulation published in 2015"

Variable-Frequency Phase Shift Modulation of a Dual Active Bridge Converter

Abstract: In this paper, a variable-frequency modulation method for a dual active bridge converter is introduced. The proposed method ensures zero-voltage switching over a wide power range with a minimal circulating current. Unlike previously presented modulation schemes, this modulation method can also be used for half-bridge variants of a traditional dual active bridge converter. The modulation method is given in a closed form, which makes it easy to apply in practice. Further, the phase drift phenomenon is discussed, and a simple phase drift compensation scheme is presented. Finally, a detailed analysis of the proposed modulation method is provided and its feasibility is verified by measurements.

Discrete-phase-randomized coherent state source and its application in quantum key distribution

Abstract: Coherent state photon sources are widely used in quantum information processing. In many applications, such as quantum key distribution (QKD), a coherent state functions as a mixture of Fock states by assuming that its phase is continuously randomized. In practice, such a crucial assumption is often not satisfied, and therefore the security of existing QKD experiments is not guaranteed. To bridge this gap, we provide a rigorous security proof of QKD with discrete-phase-randomized coherent state sources. Our results show that the performance of the discrete-phase randomization case is close to its continuous counterpart with only a small number (say, 10) of discrete phases. Compared to the conventional continuous phase randomization case, where an infinite amount of random bits are required, our result shows that only a small amount (say, 4 bits) of randomness is needed.

A High Spectral Efficiency Coherent Microwave Photonic Link Employing Both Amplitude and Phase Modulation With Digital Phase Noise Cancellation

Abstract: A high spectral efficiency coherent microwave photonic link (MPL) supporting amplitude and phase modulation incorporating a digital phase noise cancellation is proposed and experimentally demonstrated. At the transmitter, a continuous-wave light wave is amplitude- and phase-modulated by two microwave vector signals carried by a microwave carrier at an identical frequency. The modulated optical signal is polarization multiplexed with an unmodulated optical carrier and transmitted over a length of a single-mode fiber (SMF). At the receiver, the optical signal is detected coherently by a coherent receiver to which a local oscillator (LO) laser source is also applied. Through advanced digital signal processing, the microwave vector signals are recovered, and the phase noise introduced by both the transmitter laser source and LO laser source is cancelled. An experiment is performed. The transmission of a 2.5-Gb/s 16-QAM and a 1.25-Gb/s QPSK microwave vector signals both at 2.5 GHz over a 25-km SMF is implemented. The total bit rate of the MPL is 3.75 Gb/s. The transmission performance of the MPL in terms of error vector magnitudes and bit error rates is evaluated.

Carrier Phase Estimation Through the Rotation Algorithm for 64-QAM Optical Systems

Abstract: A novel low-complexity two-stage digital feed-forward carrier phase estimation algorithm based on the rotation of constellation points to remove phase modulation for a 64-ary quadrature amplitude modulation (QAM) system is proposed and analyzed both experimentally and through numerical simulations. The first stage is composed of a Viterbi and Viterbi (V&V) block, based on either the standard quadrature phase shift keying (QPSK) partitioning algorithm using only Class-1 symbols or a modified QPSK partitioning scheme utilizing both Class-1 and outer most triangle-edge (TE) symbols. The second stage applies the V&V algorithm after the removal of phase modulation through rotation of constellation points. Comparison of the proposed scheme with constellation transformation, blind phase search (BPS) and BPS+MLE (maximum likelihood estimation) algorithm is also shown. For an OSNR penalty of 1 dB at bit error rate of $10^{-2}$ , the proposed scheme can tolerate a linewidth times symbol duration product ( $\Delta \hbox{$ u $}\cdot T_{s}$ ) equal to $3.7\times 10^{-5}$ , making it possible to operate 32-GBd optical 64-QAM systems with current commercial tunable lasers.

1λ,6 bits/symbol, 280 and 350 Gb/s direct detection transceiver using intensity modulation, polarization multiplexing, and inter-polarization phase modulation

Abstract: We demonstrate 1λ, 6 bits/symbol, 280 and 350 Gb/s throughput with direct detection of polarization multiplexed PAM-4 intensity modulation and inter-polarization phase modulation over 4 phases at BERs of 2.5×10−3 (

On higher-order representations of Polyphase-Coded FM radar waveforms

Abstract: It has recently been shown that arbitrary polyphase codes can be implemented as FM waveforms through a radar-specific version of the Continuous Phase Modulation (CPM) framework. These waveforms, denoted as Polyphase-Coded FM (PCFM) can be viewed as a first-order hold representation of the phase function (where traditional codes represent a zero-order hold). Here we examine higher-order representations as a means to achieve further variety over the space of possible waveform functions one may optimize. Specifically, the relationships between the first, second, and third-order representations are considered, along with the optimization of the coding for each.

Barcode Modulation Method for Data Transmission in Mobile Devices

Abstract: The concept of 2-D barcodes is of great relevance for use in wireless data transmission between handheld electronic devices. In a typical setup, any file on a cell phone, for example, can be transferred to a second cell phone through a series of images on the LCD which are then captured and decoded through the camera of the second cell phone. In this study, a new approach for data modulation in 2-D barcodes is introduced, and its performance is evaluated in comparison to other standard methods of barcode modulation. In this new approach, orthogonal frequency-division multiplexing (OFDM) modulation is used together with differential phase shift keying (DPSK) over adjacent frequency domain elements. A specific aim of this study is to establish a system that is proven tolerant to camera movements, picture blur, and light leakage within neighboring pixels of an LCD.

CPM Signals for Satellite Navigation in the S and C Bands.

Abstract: Frequency allocations in the L band suitable for global navigation satellite system (GNSS) services are getting crowded and system providers face an ever tougher job when they try to bring in new signals and services while maintaining radio frequency compatibility. With the successive opening of the S and C bands to GNSS service, the multi-band combined navigation is predicted to become a key technology for future high-precision positioning navigation systems, and a single modulation scheme satisfying the requirements in each band is a promising solution for reducing user terminal complexity. A universal modulation scheme based on the continuous phase modulation (CPM) family suitable for the above bands’ demands is proposed. Moreover, this paper has put forward two specific CPM signals for the S and C bands, respectively. Then the proposed modulation schemes, together with existing candidates, are comprehensively evaluated. Simulation results show that the proposed CPM signals can not only satisfy the constraint condition of compatibility in different bands well and reduce user terminal complexity, but also provide superior performance in terms of tracking accuracy, multi-path mitigation and anti-jamming compared to other candidate modulation schemes.

Multi-dimensional permutation-modulation format for coherent optical communications.

Abstract: We introduce the multi-dimensional permutation-modulation format in coherent optical communication systems and analyze its performance, focusing on the power efficiency and the spectral efficiency. In the case of four-dimensional (4D) modulation, the polarization-switched quadrature phase-shift keying (PS-QPSK) modulation format and the polarization quadrature-amplitude modulation (POL-QAM) format can be classified into the permutation modulation format. Other than these well-known modulation formats, we find novel modulation formats trading-off between the power efficiency and the spectral efficiency. With the increase in the dimension, the spectral efficiency can more closely approach the channel capacity predicted from the Shannon’s theory. We verify these theoretical characteristics through computer simulations of the symbol-error rate (SER) and bit-error rate (BER) performances. For example, the newly-found eight-dimensional (8D) permutation-modulation format can improve the spectral efficiency up to 2.75 bit/s/Hz/pol/channel, while the power penalty against QPSK is about 1 dB at BER=10−3.

Carrier synchronization appropriate for alm nfc data transmission

Abstract: In some aspects, the disclosure is directed to methods and systems for carrier synchronization in active load modulation for near field communications. A broadcast carrier is received from a remote device and mixed with a locally-generated carrier and modulated data. A carrier synchronization circuit synchronizes the locally-generated carrier with the broadcast carrier based on an identified phase error from a double Cartesian-to-polar mapping of the mixed locally-generated carrier and broadcast carrier. In some implementations, the system also includes a modulation suppression circuit for providing unmodulated carrier signals to the carrier synchronization circuit or suppressing modulation distortion to maintain frequency and phase tracking despite the presence of data.

Simple Features for Separating CPFSK from QAM and PSK Modulations

Abstract: In this letter we propose simple and robust features to distinguish continuous-phase frequency shift keying from quadrature amplitude modulation and phase shift keying modulations. The features are based on sample mean and sample variance of the imaginary part of the product of two consecutive complex signal values. Root raised cosine pulses are used to generate the linearly modulated signals. Support vector machines are employed to distinguish the signals. One benefit of using support vector machines is that it requires very few realizations for training. Moreover, no a priori information is required about carrier amplitude, carrier phase, carrier offset, symbol rate, pulse shape, initial symbol phase (timing offset) and channel impulse response. Effectiveness of the features and signal separation by support vector machines is tested by observing the joint effects of additive white Gaussian noise, carrier offset, lack of symbol and sampling synchronization, and either fast or slow fading. In the course of doing that, the proposed classifier is compared to the wavelet based classifier, equipped by support vector machines.

A mm-Wave Segmented Power Mixer

Abstract: The segmented power-mixer array based mm-wave power generation architecture is demonstrated to be an energy-efficient technique for generating high-speed nonconstant envelope modulations. High output power levels are achieved by efficiently combining power from several power mixers using an area efficient dual-primary distributed active transformer. The segmented scheme leads to back-off efficiency improvements while simultaneously providing direct envelope modulation eliminating the need for high-speed high-efficiency supply modulators. The power mixer is implemented in a 32-nm silicon-on-insulator CMOS process and provides a peak output power of 19.1 dBm at 51 GHz with a drain efficiency of 14.2% and a peak power-added efficiency of 10.1%. High-speed constant (binary phase-shift keying, quadrature phase-shift keying), as well as nonconstant envelope modulations ( $m$ -amplitude shift keying, quadrature amplitude modulation) show the versatility of the architecture towards spectrally efficient modulation schemes. Reliability against segment breakdown over long periods of time at 30% higher supply voltages has also been demonstrated.

Robust Detection of Binary CPMs With Unknown Modulation Index

Abstract: We consider soft-output detection of a binary continuous phase modulation (CPM) generated through a low-cost transmitter, thus characterized by a significant modulation index uncertainty, and sent over a channel affected by phase noise. The proposed detector is designed by adopting a simplified representation of a binary CPM signal with the principal component of its Laurent decomposition and is obtained by using the framework based on factor graphs and the sum-product algorithm. It does not require an explicit estimation of the modulation index nor of the channel phase and is very robust to large uncertainties of the nominal value of the modulation index. Being soft-output in nature, this detector can be employed for iterative detection/decoding of practical coded schemes based on a serial concatenation, possibly through a pseudo-random interleaver, of an outer encoder and a CPM modulation format.

Optimised phase disposition (PD) modulation of a modular multilevel converter using a state machine decoder

Abstract: This paper presents a theoretical harmonic analysis of phase disposition (PD) and phase shifted carrier (PSC) pulse width modulation (PWM) strategies for MMC converters. It is shown that when these strategies are implemented on a per MMC arm basis, their spectral performances converge because of cancellation of odd carrier sideband groups between each phase leg's arms. An improved PD modulation strategy is then presented that uses a single PD modulator for the entire phase leg, followed by a state machine decoder that evenly distributes switching pulses to all sub-modules across the phase leg upper and lower arms to balance the distribution of sub-module commutation events. The resulting strategy achieves optimum phase leg PD spectral performance, and also achieves natural voltage balancing of the MMC sub-modules. All theoretical findings are supported by simulation and experimental results obtained using a five level MMC prototype.

Quantitative measurement of high intensity focused ultrasound pressure field by optical Phase Contrast method applying non-continuous phase unwrapping algorithm

Abstract: A fast and accurate ultrasound pressure field measurement is necessary for the progress of ultrasound application in medicine. In general, a hydrophone is used to measure the ultrasound field, which takes a long measurement time and might disturb the ultrasound field. Hence, we proposed a new method categorized in an optical method called Phase Contrast method to overcome the drawback in the hydrophone method. The proposed method makes use of the spatial DC spectrum formed in the focal plane to measure the modulated optical phase induced by ultrasound propagation in water. In this study, we take into account the decreased intensity of the DC spectrum at high ultrasound intensity to increase the measurement accuracy of the modulated optical phase. Then, we apply a non-continuous phase unwrapping algorithm to unwrap the modulated optical phase at high ultrasound intensity. From, the unwrapped result, we evaluate the quantitativeness of the proposed method.

Measurement of the complex transmittance of large optical elements with modulation coherent imaging

Abstract: Accurate measurements of the transmittance of large optical elements are essential to improve the energy density in inertial confinement fusion (ICF). The required complex transmittance of such optical elements used in ICF is obtained by computing the phase difference between the illuminating and transmitting fields using modulation coherent imaging (MCI). A phase plate designed as a modulator has a known transmission function in this technique. It presents a simple and quick method to measure the transmittance of large optical elements with irregular surface profiles by retrieving it from only two diffraction patterns recorded by a CCD camera. The complex transmittance of a continuous phase plate (CPP) with a large aperture used in ICF is measured experimentally, and the results are found to agree with the designed value.

Robust recognition of linear and nonlinear digital modulations of RRC pulse trains

Abstract: In this paper we propose simple and robust features to distinguish continuous-phase frequency shift keying from quadrature amplitude and phase shift keying modulations. Robustness is tested in the presence of SNR estimation offset, block and correlated fast fading, lack of symbol and sampling synchronization, and carrier offset. The features are based on sample mean and sample variance of the imaginary part of the product of two consecutive complex signal values. Root raised cosine pulses are used to generate the linearly modulated signals. Root raised cosine as well as rectangular shaped instantaneous frequency pulses are used in designing the continuous-phase frequency shift keying signals. Support vector machines are employed to distinguish the signals. One benefit of using support vector machines is that it requires very few realizations for training. Moreover, no a priori information is required about carrier amplitude, carrier phase, carrier offset, symbol rate, pulse shape and initial symbol phase. Performance of the proposed feature is compared to the wavelet based feature that uses support vector machines for classification.

A Flexible Modulation Scheme Design for C-Band GNSS Signals

Abstract: Due to the spectrum congestion of current navigation signals in L-band, C-band has been taken into consideration as a candidate frequency band for global navigation satellite system (GNSS). As is known, modulation scheme is the core part of signal structure, and how to design a modulation waveform that could make full use of narrow bandwidth 20 MHz and satisfy the constraint condition of frequency compatibility in C-band is the main research content of this paper. In view of transmission characteristics and constraint condition of compatibility in C-band, multi-h continuous phase modulation (CPM) is proposed as a candidate modulation scheme. Then the classical channel capacity estimation and a comprehensive evaluation criterion for GNSS modulation signals are employed to assess the proposed scheme in the aspects of the capacity over additive white Gaussian noise (AWGN), tracking accuracy, multipath mitigation, antijamming, and so on. Simulation results reveal that, through optimizing the number and size of modulation indexes, the flexible scheme could offer better performance in terms of code tracking, multipath mitigation, and antijamming compared with other candidates such as MSK and GMSK while maintaining high band efficiency and moderate implementation complexity of receiver. Moreover, this paper also provides a reference for next generation modulation signals in C-band.

Performance improvement techniques for the DVB‐RCS2 return link air interface

Abstract: Summary This paper presents performance improvement techniques for the second-generation digital video broadcast return channel via satellite air interface, which can be used for supporting future demands for Tbit/s traffic requirements. In particular, we have investigated minimum-shift keying (MSK) type of continuous phase modulation (CPM) waveforms by considering both single-carrier and multi-carrier transmission and single-amplitude and multi-amplitude signals, which improve the spectral efficiency. In addition, we consider frame timing and synchronization techniques, which make synchronization more accurate and robust. Our research has shown that the MSK single-carrier frequency-division multiple access (SC-FDMA) outperforms the quadrature phase-shift keying SC-FDMA in terms of resilience to distortion with the performance gap increasing when the amplifier shows a milder distortion. The performance of a multi-amplitude CPM scheme, based upon the superposition of two single-amplitude MSK signals at the radio frequencies level, is also investigated. In comparison with other equivalent linear modulation schemes, performance evaluation results have been shown that the proposed multi-amplitude CPM scheme significantly improves the spectral efficiency in the presence of adjacent channel interference. Finally, we have proposed a viable and efficient methodology, which enables reliable and accurate timing and frequency synchronization for the SC-FDMA satellite return link. This involves a combination of global positioning system (GPS)-based pre-compensation of differential timing between user terminals, preamble detection in an integrated random access channel, and user channel frequency estimation based on repetitive symbols in the time domain. Copyright © 2015 John Wiley & Sons, Ltd.

Order recognition of continuous-phase FSK

Abstract: In this paper we study a set of distinguishing features based on approximate entropy. The set identifies the order of continuous-time frequency shift keyings in the joint presence of carrier offset, asynchronous sampling and symbol intervals, correlated fast fading and additive white Gaussian noise. Performance of the approximate-entropy-based features is compared to the performance of wavelet-based feature. For fair comparison of the features, both the approximate-entropy- based and wavelet-based features are classified by support vector machines. Major benefit of employing support vector machines is that they are able to train themselves using a very few realizations. Also, no a priori information is required about carrier phase, symbol rate and carrier amplitude.

Sparse graph-based coding schemes for continuous phase modulations

Abstract: The use of the continuous phase modulation (CPM) is interesting when the channel represents a strong non-linearity and in the case of limited spectral support; particularly for the uplink, where the satellite holds an amplifier per carrier, and for downlinks where the terminal equipment works very close to the saturation region. Numerous studies have been conducted on this issue but the proposed solutions use iterative CPM demodulation/decoding concatenated with convolutional or block error correcting codes. The use of LDPC codes has not yet been introduced. Particularly, no works, to our knowledge, have been done on the optimization of sparse graph-based codes adapted for the context described here. In this study, we propose to perform the asymptotic analysis and the design of turbo-CPM systems based on the optimization of sparse graph-based codes. Moreover, an analysis on the corresponding receiver will be done.

Polarization division multiplexed intensity, inter polarization phase and inter polarization differential phase modulation with stokes space direct detection for 1λ×320 Gb/s 10 km transmission at 8 bits/symbol

Abstract: We propose modulation and Stokes space direct-detection of four orthogonal degrees of freedom of one laser; the intensity on two polarizations, inter-polarization phase and inter-polarization differential phase, to achieve 320 Gb/s 10 km transmission

FPGA implementation of Shaped Offset QPSK modulator

Abstract: This paper presents a novel architecture for the modulation scheme Shaped Offset QPSK (SOQPSK), which belongs to the class of Continuous Phase Modulations (CPMs). These waveforms have recently regained remarkable popularity, due to the increasing demand of highly energy and spectral efficient communication systems for deep-space, telemetry and Unmanned Aerial Vehicle (UAV) links, for example. To the best of the authors' knowledge, this is the first SOQPSK modulator architecture and implementation reported in literature. The modulation task itself is divided into a SOQPSK-specific precoding part, with minimal hardware complexity, as well as an optimized quadrature CPM modulator. With a proof-of-concept FPGA implementation, the feasibility of the proposed architecture is shown together with its close to optimal algorithmic performance.

Protograph-based LDPC convolutional codes for Continuous phase modulation

Abstract: The spatial coupling is an efficient technique that improves the threshold of Low Density Parity Check (LDPC) codes. In this paper, we investigate the performance of the serial concatenation of Continuous phase modulation (CPM) and LDPC convolutional codes over a memoryless additive white Gaussian noise channel. We show that coupling protographs optimized for CPM improves their performance and helps designing very good ‘small’ protographs. Inspired from convolutional codes and thanks to the inner structure of CPM, we also introduce a new termination without rate loss but that still exhibits a coupling gain and it thus has a very good threshold. We will illustrate the behavior of different LDPC convolutional codes with different termination methods by giving some examples and studying their performance using multidimensional EXIT analysis.

A novel modulation scheme for user devices equipped with a single-RF MIMO transmitter

Abstract: A new modulation technique called Multi-Dimensional Continuous Phase Modulation (MCPM) is proposed for user devices with a single-RF MIMO transmitter in cellular communications. MCPM has a Peak to Average Power Ratio (PAPR) equal to 0dB, thus the power amplifier in user terminal works with the highest power efficiency. In fact, MCPM is a generalization of classical CPM for multiple antennas systems. It is shown that using a few number of antennas, MCPM reaches to the capacity of Gaussian input approximately. Utilizing MCPM modulation in user device enables us to implement very cheap power amplifier while there is negligible loss in information capacity. Discrete constellation MCPM is also proposed and its mutual information is presented using some numerical techniques.

Binary Continuous Phase Modulations Robust to a Modulation Index Mismatch

Abstract: We consider binary continuous phase modulation (CPM) signals used in some recent low-cost and low-power consumption telecommunications standard. When these signals are generated through a low-cost transmitter, the real modulation index can end up being quite different from the nominal value employed at the receiver and a significant performance degradation is observed unless proper techniques for the estimation and compensation are employed. For this reason, we design new binary schemes with a much higher robustness. They are based on the concatenation of a suitable precoder with binary input and a ternary CPM format. The result is a family of CPM formats whose phase state is constrained to follow a specific evolution. Two of these precoders are considered. We will discuss many aspects related to these schemes, such as the power spectral density, the spectral efficiency, simplified detection, the minimum distance, and the uncoded performance. The adopted precoders do not change the recursive nature of CPM schemes. So these schemes are still suited for serial concatenation, through a pseudo-random interleaver, with an outer channel encoder.

Performance comparison of Kalman filter and maximum likelihood carrier phase tracking for weak GNSS signals

Abstract: GNSS carrier phase measurement capability is one of the most important features for high performance/accuracy receivers. However significant signal attenuation due to blockage and multipath as experienced indoors for example, degrades carrier phase quality in standard carrier phase tracking loops using PLL or KF-PLL. Under such conditions, the receiver may not be able to generate reliable carrier phase measurements either due to weak signal, fading or fragility of conventional tracking loops. One contribution of this paper is the proposed decoupled maximum likelihood carrier phase, Doppler and Doppler rate tracking architecture. This approach first independently estimates Doppler rate and Doppler based on power spectra and then estimates the carrier phase if possible. In order to assess the actual carrier phase measurement quality, controlled simulation is also conducted after analyzing the overall phase tracking performance. Double differenced carrier phase results as well as RTK solutions show that the proposed method works well and is able to generate reliable carrier phase measurement and centimeter level solution when the carrier-to-noise-density ratio (C/N0) is about 20 dB-Hz.

A virtual resampling technique for algebraic two-dimensional phase unwrapping

Abstract: Two-dimensional (2D) phase unwrapping is a reconstruction problem of a continuous phase, defined over 2D-domain, from its wrapped samples. In our previous work, we presented a two-step phase unwrapping algorithm which first constructs, as the real and imaginary parts of a complex function, a pair of piecewise polynomials having no common zero over the domain, then estimates the unwrapped phase by applying the algebraic phase unwrapping. In this paper, we propose a preprocessing of the above algorithm for avoiding the appearance of zeros of the complex function in the first step. The proposed preprocessing is implemented by a convex optimization and resampling, and its effectiveness is shown in a terrain height estimation by the interferometric synthetic aperture radar.

Characterization of polarization-independent phase modulation method for practical plug and play quantum cryptography

Abstract: We characterized a polarization-independent phase modulation method, called double phase modulation, for a practical plug and play quantum key distribution (QKD) system. Following investigation of theoretical backgrounds, we applied the method to the practical QKD system and characterized the performance through comparing single phase modulation (SPM) and double phase modulation. Consequently, we obtained repeatable and accurate phase modulation confirmed by high visibility single photon interference even for input signals with arbitrary polarization. Further, the results show that only 80% of the bias voltage required in the case of single phase modulation is needed to obtain the target amount of phase modulation.

Modulation and Demodulation

Abstract: This chapter provides an overview of analog modulation and frequency modulation (FM). Information is encoded through a variation of the phase of the carrier wave in phase modulation (PM). An alternative approach is to not map a zero data bit to a carrier signal which is turned off, but rather to a carrier signal with a negative amplitude, which is referred as amplitude shift keying (ASK). A way to modulate digital data onto an analog carrier is to apply data‐dependent phase shifts to the carrier signal, referred to as phase shift keying (PSK). Information bits are represented in a change of frequency of the carrier in binary frequency shift keying (BFSK). Pulse shaping enables successful demodulation at the receiver side. Orthogonal frequency division multiplex (OFDM) and orthogonal frequency division multiple access (OFDMA) are multiplexing and multiple access schemes, respectively, including a particular choice of pulse shape and modulation concept.