PSK Signals Research Articles

Heterodyne mixing and polarization diversity techniques in radio over fiber system with high sensitivity and dispersion tolerance

We propose and experimentally demonstrate the heterodyne mixing and polarization diversity techniques in radio over fiber (ROF) systems with the advantages of high sensitivity and dispersion endurance. The generation of 2.5 Gb/s optical DPSK and PSK signals, fiber propagation and wireless transmission over 15 GHz subcarrier are illustrated with very low sensitivity of −26 and −32 dBm, respectively. Moreover, based on the wireless polarization diversity techniques, we successfully performed the transmission of 1.3 Gb/s uncompressed high definition television (HDTV) signals with high quality.

Phase Predistortion of a Class-D Outphasing RF Amplifier in 90 nm CMOS

This brief presents a behavioral model structure and a model-based phase-only predistortion method that are suitable for outphasing RF amplifiers. The predistortion method is based on a model of the amplifier with a constant gain factor and phase rotation for each outphasing signal, and a predistorter with phase rotation only. The method has been used for enhanced data rates for GSM evolution (EDGE) and wideband code-division multiple-access (WCDMA) signals applied to a Class-D outphasing RF amplifier with an on-chip transformer used for power combining in 90-nm CMOS. The measured peak power at 2 GHz was +10.3 dBm with a drain efficiency and power-added efficiency of 39% and 33%, respectively. For an EDGE 8 phase-shift-keying (8-PSK) signal with a phase error of 3° between the two input outphasing signals, the measured power at 400 kHz offset was -65.9 dB with predistortion, compared with -53.5 dB without predistortion. For a WCDMA signal with the same phase error between the input signals, the measured adjacent channel leakage ratio at 5-MHz offset was -50.2 dBc with predistortion, compared with -38.0 dBc without predistortion.

A NOVEL ULTRA-FAST ULTRA-SIMPLE ADAPTIVE BLIND BEAMFORMING ALGORITHM FOR SMART ANTENNA ARRAYS

This research proposes a new blind tracking algorithm for smart antenna arrays by switching the main beam iteratively using the cost calculated from the received and predicted symbol. This al- gorithm will be called Cost Steering Algorithm Using Demodulation- Remodulation Technique COSTAUS/DRT. It is completely indepen- dent of the Least Mean Squares (LMS) or any derived version from it, and it does not need to investigate the cyclostationary properties of the incoming signal. A complete derivation and analytical model with simulation using Simulink is given in this research. The algorithm was tested under three difierent target motions which are a triangular mo- tion (linear), sinusoidal motion (circular) and saw tooth motion which is an adverse case when the linear motion changes its path suddenly. The transmitter uses 16-level PSK signal with no Forward Error Cor- rection code (FEC) in order to test the algorithm under the worst situation. The algorithm is tested under difierent noise power levels. The antenna array is a linear array with 16-elements.

Computationally Efficient Maximum Likelihood Sequence Estimation and Activity Detection for $M$-PSK Signals in Unknown Flat Fading Channels

In this letter, we develop a computationally efficient algorithm for the Maximum Likelihood (ML) sequences estimation (MLSE) of an M-ary Phase Shift keying ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> -PSK) signal transmitted over a frequency non-selective slow fading channel with an unknown complex amplitude and an unknown variance additive white Gaussian noise. The proposed algorithm also provides the ML estimates of the complex amplitude and the noise variance that are critical in signal activity detection and demodulation in the modern cognitive communication receivers. We prove the optimality of the proposed algorithm and compare its performance via simulation with a recent suboptimal algorithm.

Transmission of 125-Gb/s PSK signal generated by using RSOA in 110-km coherent WDM PON

We generate the phase-modulated signal by utilizing the chirp characteristics of the directly-modulated reflective semiconductor optical amplifier (RSOA) for the cost-effective realization of a long-reach wavelength-division-multiplexed passive optical network (WDM PON). We first investigate the relation between the amplitude and phase modulation indices in a directly-modulated RSOA and optimize these modulation indices to maximize the symbol distance on the constellation diagram. The results show that, by operating the RSOA under this optimum condition, we can achieve the excellent receiver sensitivity of -49.8 dBm at 1.25 Gb/s. We implement a long-reach WDM PON by using the phase-modulated RSOAs and self-homodyne receivers, and demonstrate the error-free transmission of 1.25-Gb/s signal over a 110-km long link without using any optical amplifiers.

Noncoherent Frame Synchronization

One of the key operations in communication systems is frame synchronization, which is similar in many aspects to code acquisition in the context of code division multiple access systems. We focus on frame synchronization for binary PSK signals in the presence of additive white Gaussian noise and phase offset due to imperfect carrier phase estimation. We derive optimum and low-complexity suboptimum synchronization techniques, showing large improvements with respect to frame synchronization based on noncoherent correlation. Extensions to higher order modulations and fading channels are also discussed.

A role for PSK signaling in wounding and microbial interactions in Arabidopsis

PSK-alpha is a disulfated peptide that acts as a growth factor in plants. PSK-alpha is derived from preproproteins which are encoded by five PSK precursor genes in Arabidopsis thaliana (L.) Heynh and is perceived by leucine-rich repeat receptor kinases. Arabidopsis has two PSK receptor genes, PSKR1 and PSKR2. Although ligand and receptor are well characterized, the biological functions of PSK signaling are not well understood. Using reporter lines and receptor knockout mutants of Arabidopsis, a role for PSK signaling in biotic interactions and in wounding was analyzed. Treatment of Arabidopsis leaves with the fungal elicitor E-Fol, or the fungal pathogens Alternaria brassicicola and Sclerotinia sclerotiorum resulted in induction of PSK2 and PSKR1 as shown by promoter:GUS analysis. Wounding of hypocotyls or leaves induced PSK3:GUS, PSK5:GUS and PSKR1:GUS expression indicating that PSK precursor genes are differentially regulated in response to specific stresses. The receptor knockout lines pskr1-3 and pskr2-1 showed significantly reduced photosynthesis in response to the fungal elicitor E-Fol which indicates that fungal defence is impaired. pskr1-3 plants further showed reduced growth of crown galls after infection with Agrobacterium tumefaciens. A role for PSK signaling in Agrobacterium tumefaciens tumor growth was supported by the finding that PSK precursor genes and PSKR1 are expressed in crown galls. Overall, the results indicate that PSK signaling may play a previously undescribed role in pathogen or herbivore interactions and is crucial for Agrobacterium-induced cell proliferation in crown gall formation.

System Impact of Cascaded All-Optical Wavelength Conversion of D(Q)PSK Signals in Transparent Optical Networks

We will compare techniques for all-optical wavelength conversion of differentially phase-modulated signals using four-wave mixing and super-continuum generation. For the super-continuum generation, a relation between the conversion efficieny and the nonlinear phase distortion will be derived and it will be shown that this technique is not suitable for the conversion of phase-modulated signals. For the four-wave mixing, techniques for the improvement of the conversion efficiency will be studied. Mainly the suppression of Brillouin scattering and its impact on phase-distortions will be discussed. A detailed discussion of its cascadability in transparent optical networks will conclude the contribution. The introduction of a maximum outage probability can significantly relax the OSNR requirements.

Equalisation of a wireless ATM channel using a pruned recurrent neural network

A equalisation method of a wireless Asynchronous Transfer Mode (ATM) communication channel using a Complex BiLinear Recurrent Neural Network (CBLRNN) is proposed in this paper. A Genetic Algorithm (GA) is used for the pruning process of the trained CBLRNN. As a result, a pruned Bilinear Recurrent Neural Network (BLRNN) is obtained and the pruned BLRNN can reduce the computational cost by 29.9% in terms of the number of weights. The equaliser based on CBLRNN pruned by the GA is compared with Decision Feedback Equaliser (DFE), Volterra filter based equaliser, and Multilayer Perceptron Neural Network Equaliser. Experiments show that the pruned CBLRNN equaliser for 8PSK signals gives favourable results in the Symbol Error Rate (SER) criterion over conventional equalisers.

Open‐loop analysis and self‐noise performance of an NDA synchroniser for carrier‐independent symbol timing recovery at baud rate

AbstractFeedback loops for symbol timing recovery are an attractive solution for continuous transmission of data, where rapid acquisition is not so important as in burst‐mode systems. In this context, carrier‐independent non‐data‐aided (NDA) timing error detectors, operated at only one sample per symbol, can be a most interesting option. Assuming M‐ary PSK signals and focusing on a linearised loop model for analytical work, such an algorithm has been discussed already in the technical literature. On the other hand, the linear approach does not apply for larger deviations from the stable equilibrium point as they are encountered during initial acquisition. In this case, the detector characteristic (S‐curve) must be known. Since not available from the open literature, it is derived in this paper not only for PSK but for linear modulation schemes in general. The slope in the stable equilibrium point is given in closed form such that the linearised tracker can be specified immediately. Furthermore, it turned out that the complexity of the detector, but also the computation of both S‐curve and slope, is most simple for a special value of the additional design parameter characterizing the algorithm. Based on this, the self‐noise variance is derived in closed form. For M‐PSK schemes, it is proved that they experience no jitter floor due to pattern (data) noise. On the other hand, for non‐constant modulus signals, like QAM or APSK constellations, it is shown that the performance is proportional to the loop bandwidth. Finally, a detailed comparison with NDA maximum‐likelihood and Gardner algorithm, as standard method for carrier‐blind NDA tracking, is presented. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Quality Monitoring of DxPSK Signals by Using Differential Phasor Diagram

We describe a new method for quantitative evaluation of the quality of multilevel differential phase-shift-keyed (DxPSK) signals by using a differential phasor monitor. This method measures the phase deviation of the symbols in the differential phasor diagram and estimates the bit-error rate (BER) by using a simple relation based on the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> -factor defined for multilevel DxPSK signals. We demonstrate that the proposed method can accurately estimate the BER of differential quadrature PSK and 8-ary PSK signals.

Co- and Counterphasing Tolerances for Dual-Pump Parametric $\lambda$-Conversion of D(Q)PSK Signals

Recently, we have shown that a pump-phase modulation in single-pump parametric wavelength converters introduces severe signal degradations on differential (quadrature) phase-shift keying signals. In this letter, we extend our investigations to dual-pump parametric wavelength converters. It will be shown that even small deviations from ideal co- and counterphasing can lead to similar optical signal-to-noise ratio penalties as in the single-pump case. This nonideal behaviour can occur due to imperfections in the pump-phase modulation scheme as well as through walk-off between the pumps that is unavoidable for full tunable operation.

All-optical signal regeneration using fiber nonlinearity

Signal regeneration schemes using fiber nonlinearity are reviewed. Phase-preserving noise reduction of PSK signals using saturation of fiber-optic parametric amplifier is described in detail. Multi-channel reshaping by a single nonlinear medium is also discussed.

Achieving maximum space‐time‐frequency diversity in shallow water acoustic channels: System design and experimental results.

This work sheds light on the individual impact of coded modulation and diversity in achieving reliable underwater acoustic (UWA) communications. Two systems with the same bit‐rate and complexity but different diversity order are designed and compared. The “conventional” system combines trellis coded modulation (TCM), symbol interleaving and an 8PSK signal set. The “alternative” or bit‐interleaved coded modulation (BICM) system combines a convolutional code, bit interleaving, and a 16QAM signal set. Both systems are coupled with orthogonal frequency division multiplexing (OFDM) to cope with the intersymbol interference (ISI). When two or three projectors are used, the above coding schemes are concatenated with space‐time block codes (STBC). Bit‐error rates using data recorded during the RACE’08 off the coast of Narragansett, USA are computed demonstrating the superiority of BICM schemes relative to their TCM counterparts over an extensive collection of shallow water channels, thus proving that BICM is a promising technique towards achieving reliable UWA communications. In particular, by using BICM and 4 kHz of bandwidth, we have successfully accomplished a 7150 b/s transmission rate over 1 km range.

Simulation and Numerical Analysis of Wireless PSK Systems with Imperfect Carrier Phase Recovery

The bit error probability (BEP) of binary and quaternary PSK (BPSK and QPSK) signals over Rayleigh fading channel with imperfect carrier-phase recovery is derived. The channel is assumed to be slow and frequency-nonselective in which the received signal is constant over at least two symbol intervals. Numerical values for the average BEP are obtained by integrating the conditional BEP expression over the carrier-phase error distribution. The resultant integrands have only elementary functions, such as exponentials and algebraic power functions and can, therefore, be explicitly evaluated to any degree of accuracy. The accuracy of this approach is verified through proposing an efficient quazi-analytical simulation technique.

PSK‐α promotes root growth in Arabidopsis

Phytosulfokine-α (PSK-α) is a disulfated pentapeptide described to act as a growth factor in suspension cells. In this study, the involvement of PSK signaling through the PSK receptor gene AtPSKR1 in Arabidopsis root growth was assessed.Expression studies of PSK precursor genes and of AtPSKR1 were performed in roots with RT-PCR and P:GUS analyses. Root elongation, lateral root formation, cell production and root cell elongation were analyzed in wild-type (wt) and in the receptor knockout mutant Atpskr1-T treated with or without synthetic PSK-α.Phytosulfokine and AtPSKR1 genes are differentially expressed in roots. PSK-α induced root growth in a dose-dependent manner without affecting lateral root density. Kinematic analysis established that enhancement of root growth by PSK-α was mainly caused by an increase in cell size. In Atpskr1-T, the primary roots were shorter as a result of reduced mature cell size and a smaller root apical meristem composed of fewer cells than in wt.The results indicate that PSK-α signaling through AtPSKR1 affects root elongation primarily via control of mature cell size. Root organogenesis, on the other hand,is not controlled by PSK-α.

Fuzzy clustering algorithm based on genetic algorithm and its application

A fuzzy clustering arithmetic based on Genetic Algorithm(GA) was proposed.Genetic algorithms instructed to choose the initial cluster centers firstly,and clustering was processed by Fuzzy C-Mean Clustering(FCM).It not only overcomes the sensitivity to initial centers as FCM,but also solves the problem of approximate solution as Genetic Algorithm.This method was applied to constellation clustering and modulation recognition.The simulation results show that the method is feasible to PSK and QAM signal even when timing error exists.

Detecting the presence of psk signals using composite hypothesis testing

In this paper, we study the problem of signal- presence detection, assuming a generic source transmission which can consist of separate pilot and data portions, in the high-power regime. In particular, we derive the optimum non- decision-directed test for the signal-presence hypothesis, which universally applies to all PSK data modulation strategies. For wireless fading channels, the optimum decision test is obtained by computing and thresholding a new proposed decision statistic: the hybrid non-coherent accumulation. Hybrid accumulation combines magnitude and power accumulations of the received antenna data, across multiple coherence intervals, or multiple coherence bands. All findings in this paper are derived theoretically, and subsequently verified using computer simulations.

Space-Time Convolutional Codes over Finite Fields and Rings for Systems with Large Diversity Order

We propose a convolutional encoder over the finite ring of integers modulo pk, Zpk, where p is a prime number and k is any positive integer, to generate a space-time convolutional code (STCC). Under this structure, we prove three properties related to the generator matrix of the convolutional code that can be used to simplify the code search procedure for STCCs over Zpk. Some STCCs of large diversity order (≥4) designed under the trace criterion for n = 2, 3, and 4 transmit antennas are presented for various PSK signal constellations.

Precoded Differential Orthogonal Space-Time Modulation Over Correlated Ricean MIMO Channels

In this paper, we study a differential system employing orthogonal space-time block codes (OSTBC) with -PSK, -PAM, and -QAM constellations, over arbitrarily correlated Ricean fading channels. The symbol error rate (SER) performance analysis of such a differential system is performed using a memoryless precoding matrix at the transmitter. Monte Carlo simulations are carried out to verify the validity of the SER expressions. The SER formulas can predict the behavior of differential system closely for moderate to high values of signal to noise ratio (SNR). The proposed precoded differential codes differ from the previous works by: 1) the precoded differential code is proposed for the arbitrarily correlated Ricean channels, whereas, existing work is applicable for Rayleigh fading channels using Kronecker model with transmit correlation only. 2) the previous work is applicable to the OSTBC with -PSK signal constellations only, whereas, the proposed precoded differential coding works with -PSK, -QAM, and -PAM constellations. 3) the precoder design is proposed to minimize the approximate SER, whereas the previous precoder is based on minimizing an upper bound of the approximate SER. In addition, the proposed precoded orthogonal differential code performs better than the previously proposed eigen-beamforming based precoded differential OSTBC.