M-ary Phase Shift Keying Signals Research Articles

Sub-Nyquist Sampling and Measurement of MPSK Signal Based on Parameter Matching

Accurate measurement of the M-ary Phase Shift Keying (MPSK) signal determined by finite parameters per unit of time is significant in engineering fields such as digital microwave and satellite communication. In this paper, we propose a sub-Nyquist sampling system with two channels for measuring characteristic parameters of MPSK signals based on the Finite Rate of Innovation (FRI) sampling theory. The carrier frequency parameter measurement process is modeled as a convex optimization problem, solvable using the parameter matching method on the estimated grid. The minimum harmonic frequency of the carrier is determined to build the exact grid, and the carrier frequency is estimated through a greedy search based on the given cost function. Even when the truth value of the carrier frequency is unknown, the discontinuity location parameters can be measured with high precision using the spectral estimation method on the Fourier coefficients of the MPSK signal. We propose an upper bound on the estimation error of this separable measurement method for signals with one segment. The amplitude and phase parameters can be measured by solving a least square problem. Our proposed measurement system, with lower hardware complexity, can accurately measure the MPSK signal with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> segments by sampling only 2 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> +5 points in a period, at a much lower sampling rate than the carrier frequency. Numerical simulations and hardware experiments demonstrate the superior performance of our state-of-the-art measurement method.

All-optical simultaneous amplitude and phase regeneration for MPSK signal with ASE noise based on two-wave PSA

A phase sensitive amplification (PSA) regeneration model for M-ary phase shift keying (MPSK) signals with amplified spontaneous emission (ASE) noise based on the interference between signal and its (M+1)th harmonic is proposed. Compared with the existing models based on different combinations of signal and harmonics, the new regeneration model is optimal in theory to deal with the MPSK signal degraded by ASE noise. The QPSK format is taken as an example for simulation verification and two existing classic models are also performed with the same parameters for comparison. The regeneration performance is evaluated by input–output constellations, phase and amplitude regeneration factors, and the relay distance at the bit error rate (BER) of 3.8×10−3 by measuring the transmission reach after the regenerator. The results show that the new model has the optimal relay performance for ASE-noise MPSK format, which is promising to be applied in large-capacity, flexible, and reliable optical transport networks.

Parameter Measurement of $M$ -Ary PSK Signals With Finite Rate of Innovation

Measurement of parameters of $M$ -ary phase shift keying (MPSK) signals is significant for radar and communication systems. Traditional parameter measurement methods require very high sampling rates and heavy processing to estimate the key parameters of amplitude, carrier frequency, phases, and discontinuity locations. We propose a multichannel cooperative sampling system using the finite rate of innovation sampling theorem to address this problem. In our two-channel system, the main channel estimates the MPSK amplitude and carrier frequency using a nonlinear process and time-staggered sampling structure, while the cooperative channel determines phases and discontinuity locations with an annihilating filter using the main channel’s estimated carrier frequency. Our system enables recovery of these parameters from as few as $2K+6$ samples from MPSK signals with $K$ segments. We also present a hardware platform implementing the structure. The simulation and experimental results demonstrate the effectiveness and robustness of the proposed method.

Multicell multiuser massive MIMO channel estimation and MPSK signal block detection applying two-dimensional compressed sensing

For the uplink multicell massive multiple-input multiple-output (MIMO) block fading systems, a two-dimensional smoothed l0 channel estimation method (2D-SL0-CE) with the aid of virtual channel representation is firstly exploited in this paper, which can jointly estimate the desired multiuser channels of the target cell and the interference links from neighbor cells without inducing pilot contamination. Then, a 2D-SL0 signal detection method (2D-SL0-SD) with the aid of sparse decomposing and the modified 2D sl0 recovery algorithm is proposed, which can jointly decode M-ary phase-shift keying (MPSK) signal block for whole desired users. Moreover, an improved 2D-SL0-SD is also proposed to remove multiuser interference of neighbor cells in high SNR scenario. Simulation results show that the 2D-SL0-CE method can remove performance floor induced by pilot contamination and need less pilot overhead than the conventional least square (LS) method. When detecting QPSK signal blocks at 12 dB SNR, the 2D-SL0-SD method with perfect channel state information (CSI) can obtain 10−2 BER. Moreover, in the case of 8PSK signals, the 2D-SL0-SD joining with the 2D-SL0-CE can obtain 10−2 BER at 20 dB SNR.

Performance Comparison of Selection Combining With Full CSI and Switch-and-Examine Combining With and Without Post-Selection

Selection combining (SC) with full channel state information (CSI) achieves full diversity order in a decode-and-forward (DF) relaying system. However, the estimation of CSI of all the links is a cumbersome process. As an alternative, switched-diversity techniques have been proposed in the literature, in which CSI of all the links are not simultaneously required. In this paper, we compare the variants of the switched-diversity and full-CSI SC schemes through a paired error approach for a multi-DF-relaying-based cooperative diversity system. We derive the exact symbol error probability (SEP) expressions for the full-CSI SC, switch-and-examine combining (SEC), and SEC with post-selection (SECps) schemes, considering $M$ -ary phase-shift keying (MPSK) signaling over slow, flat, independent, and nonidentical Nakagami- $m$ fading channels. It is to be noted that the derived SEP expressions are valid for integer values of fading severity parameter $m$ . In addition, we also present the closed-form asymptotic SEP expressions for MPSK signaling to evaluate the diversity order. Concisely, from the numerical results, it is observed that the SECps scheme is able to offer the same performance as that of the full-CSI SC scheme. Furthermore, the SECps scheme outperforms the SEC scheme with more CSI.

Chaotic modulations and performance analysis for digital underwater acoustic communications

Two modulation schemes, M-ary phase shift keying (MPSK) and M-ary frequency shift keying (MFSK), are commonly used for coherent and incoherent digital communications, respectively. Despite wide applications in underwater acoustic (UWA) communications, they are not suitable for confidential applications for their well-known generating processes and signal features. In this paper, two corresponding chaotic modulation methods are proposed to improve their security, namely chaotic MPSK (CMPSK) and chaotic MFSK (CMFSK). By application of chaotic sequences into the modulation procedures, they can prevent the unauthorized receivers from extracting information from the intercepted signals even with high SNR. The confidential performance of chaotic modulations is evaluated by a designed automatic modulation classification (AMC) system. Simulation results indicate a success identification rate of more than 90% for the MPSK and MFSK signal at the SNR from −10dB to 40dB, but only an identification rate of nearly zero for the CMPSK and CMFSK signal. Therefore, chaotic modulations have lower available probability and can achieve higher confidential performance. Also, an experiment was conducted to verify the performance of chaotic modulations in actual UWA communications. The experimental results show that chaotic modulations can achieve similar bit error ratio (BER) compared with conventional digital modulations, which verifies potential applications of chaotic modulations in confidential UWA communications.

Performance analysis of Switched Selection Combining with MPSK signaling for cooperative diversity systems

Cooperative diversity has been proved to be a technique which achieves higher data rate and throughput. We consider a single-relay cooperative diversity system employing decode and forward (DF) protocol. In this work, we present a new diversity combining technique which we call it as “Switched Selection Combining”, in which we combine the ideas of switched diversity and selection combining. In this technique, first, destination compares the instantaneous signal to noise ratio (SNR) of source-to-destination link with a threshold, if it is above threshold, the destination selects source-to-destination link else the destination compares the instantaneous SNR of source-to-destination link with relay-to-destination link and chooses whichever is higher. We derive the exact end-to-end symbol error probability of Switched Selection Combining with M-ary phase-shift keying (MPSK) for a flat Rayleigh fading. Results show that the Switched Selection Combining outperforms the conventional selection combining and the direct communication between the source and destination.

A New Classification Algorithm of MPSK Signals Based on Phase Distribution

Based on the phase distribution which is defined in this paper, a new classification algorithm of M-ary phase shift keying (PSK) signals is proposed. To classify the modulation type of the M-ary PSK signal, the phase distribution of the unclassified signal is calculated firstly, and then the characters of the signal modulation are extracted by computing the FFT of the phase distribution. Moreover, the method is improved in this paper that it is extended to MPSK baseband signals with frequency offset, and the calculation complexity is reduced. Simulation result shows that the accuracy rate of the classification of BPSK, QPSK and 8PSK signals can reach 98.5% when the symbol length is 500, SNR is 3dB, and 16PSK signals can also be well classified when the SNR improves to 9dB.

Achieving Full Diversity in Multi-Antenna Two-Way Relay Networks via Symbol-Based Physical-Layer Network Coding

This paper considers physical-layer network coding (PNC) with M-ary phase-shift keying (MPSK) modulation in two-way relay channel (TWRC). A low complexity detection technique, termed symbol-based PNC (SPNC), is proposed for the relay. In particular, attributing to the outer product operation imposed on the superposed MPSK signals at the relay, SPNC obtains the network-coded symbol (NCS) straightforwardly without having to detect individual symbols separately. Unlike the optimal multi-user detector (MUD) which searches over the combinations of all users' modulation constellations, SPNC searches over only one modulation constellation, thus simplifies the NCS detection. Despite the reduced complexity, SPNC achieves full diversity in multi-antenna relay as the optimal MUD does. Specifically, antenna selection based SPNC (AS-SPNC) scheme and signal combining based SPNC (SC-SPNC) scheme are proposed. Our analysis of these two schemes not only confirms their full diversity performance, but also implies when SPNC is applied in multi-antenna relay, TWRC can be viewed as an effective single-input multiple-output (SIMO) system, in which AS-PNC and SC-PNC are equivalent to the general AS scheme and the maximal-ratio combining (MRC) scheme. Moreover, an asymptotic analysis of symbol error rate (SER) is provided for SC-PNC considering the case that the number of relay antennas is sufficiently large.

General interference analysis of M-QAM and M-PSK wireless communications

This work includes an accurate and general technique, which has been developed to analyze the symbol-error-rate (SER) of coherent M-Quadrature Amplitude Modulation (QAM) and Phase Shift Keying (PSK) schemes for various conditions of the transmission. A calculation scheme has been presented dealing with Additive White Gaussian Noise and different fading effects influencing the analyzed M-ary QAM or PSK signals. Furthermore, the authors have considered the effects of multiple interference signals embedded into a stochastic model having numerous parameters, which can be assumed as random variables with adjustable distributions. The resulted M-QAM and M-PSK SER expressions have been extended for multi-carrier transmission based on the analytical calculation of the stochastic interference model.

Automatic Modulation Identification of MPSK Signals Using Differential Signal and its Higher Order Cumulants

Automatic modulation classification plays a significant role in intelligent communication. A new method based on feature extraction is proposed for the recognition of M-ary Phase Shift Keying (MPSK) signals. As features, fourth and eighth order cumulants of the input samples and phase differential sequences were applied. It is shown that the cumulant-based features have robust anti-noise ability. Simulation results demonstrate that the correct classification probability (Pcc) with the proposed algorithm is higher than the existing approaches at low signal-to-noise ratio (SNR).

S+N Energy Selection Combining for MPSK and 16-QAM Signaling in Nakagami-m and Rician Fading Channels

A signal-plus-noise (S+N) energy selection diversity combining (S+N-ESC) scheme for M-ary phase shift keying (MPSK) in Rayleigh fading channels is mathematically analyzed. Also, the S+N-ESC scheme for MPSK and 16-quadrature amplitude modulation (16-QAM) signaling in Nakagami-m and Rician fading channels is studied by computer simulations. The S+N-ESC selects the branch with the maximum S+N energy for detection. The advantage of the S+N-ESC scheme is that it requires no explicit channel estimation for diversity branch selection. We show that the symbol error probability (SEP) of the S+N-ESC is the same as that of classical selection combining (SC) for MPSK signaling in independent and identically distributed (i.i.d.) Rayleigh fading channels. Also, we show that the SEP of a weighted S+N-ESC scheme is the same as that of classical SC for MPSK signaling in independent and nonidentically distributed (i.n.d.) Rayleigh fading channels. It is shown by computer simulations that the S+N-ESC scheme provides a smaller SEP than classical SC for MPSK signaling in nondispersive fading channels such as Nakagami-m fading channels with Nakagami parameter m >; 1 and Rician fading channels with Rician parameter K >; 0. On the other hand, the S+N-ESC scheme is shown by computer simulations to have a larger SEP than classical SC for 16-QAM signaling in Nakagami-m and Rician fading channels.

M-ary symbol error outage over Nakagami-m fading channels in shadowing environments

This letter addresses the problem of finding a tractable expression for the symbol error outage (SEO) in flat Nakagami-m fading and shadowing channels. We deal with M-ary phase shift keying (M-PSK) and quadrature amplitude modulation (M-QAM) which extends our previous results on BPSK signaling. We propose a new tight approximation of the symbol error probability (SEP) holding for M-PSK and M-QAM signals which is accurate over all signal to noise ratios (SNRs) of interest. We derive a new generic expression for the inverse SEP which facilitates the derivation of a tight approximation of the SEO in a lognormal shadowing environment.

Erased-Chase decoding for RS-coded MPSK signaling over a Rayleigh fading channel

In this paper, a novel dual-metric, the maximum and minimum Squared Euclidean Distance Increment (SEDI) brought by changing the hard decision symbol, is introduced to measure the reliability of the received M-ary Phase Shift Keying (MPSK) symbols over a Rayleigh fading channel. Based on the dual-metric, a Chase-type soft decoding algorithm, which is called erased-Chase algorithm, is developed for Reed-Solomon (RS) coded MPSK schemes. The proposed algorithm treats the unreliable symbols with small maximum SEDI as erasures, and tests the non-erased unreliable symbols with small minimum SEDI as the Chase-2 algorithm does. By introducing optimality test into the decoding procedure, much more reduction in the decoding complexity can be achieved. Simulation results of the RS(63, 42, 22)-coded 8-PSK scheme over a Rayleigh fading channel show that the proposed algorithm provides a very efficient tradeoff between the decoding complexity and the error performance. Finally, an adaptive scheme for the number of erasures is introduced into the decoding algorithm.

An Extended Pawula F-Function for MPSK Signal Vector Perturbed by Correlated Two-Dimensional Gaussian Noise

This letter presents an extended Pawula F-function for computing the error rate of generalized M-ary phase shift keying (MPSK) system in the presence of phase error, quadrature error, and I-Q gain mismatch over additive white Gaussian noise (AWGN) and fading channels. The extended Pawula F-function conditioned on an instantaneous fading carrier-to-noise ratio (CNR) is derived in the form of the Craig representation.

An adaptive coherent receiver for MPSK/MDPSK over the nonselective Rayleigh fading channel with unknown characteristics

A coherent symbol-by-symbol (SBS) diversity receiver for m-ary phase-shift keying (MPSK) and differentially encoded MPSK (MDPSK) signals transmitted over a nonselective Rayleigh fading channel is presented. It incorporates a new adaptive filter for channel estimation that does not require any prior knowledge of the fading process model. It estimates the fading gains through decision-feedback and recursive least squares adaptation of the filter coefficients. A novel forgetting-factor adaptation algorithm that enables the filter to react quickly to randomly changing fading statistics caused by shadowing and acceleration/deceleration is introduced. Simulations show that the receiver performs better than that of Adachi's ( IEEE Trans. Veh. Technol. vol. 47 p. 909, 1998), either without shadowing or under slow lognormal shadowing.

Feedforward neural network for blind equalization with PSK signals

Most of the cost functions used for blind equalization are nonconvex and nonlinear functions of tap weights, when implemented using linear transversal filter structures. Therefore, a blind equalization scheme with a nonlinear structure that can form nonconvex decision regions is desirable. The efficacy of complex-valued feedforward neural networks for blind equalization of linear and nonlinear communication channels has been confirmed by many studies. In this paper we present a complex valued neural network for blind equalization with M-ary phase shift keying (PSK) signals. The complex nonlinear activation functions used in the neural network are especially defined for handling the M-ary PSK signals. The training algorithm based on constant modulus algorithm (CMA) cost function is derived. The improved performance of the proposed neural network in both, stationary and nonstationary environments, is confirmed through computer simulations.

A Modified Gardner Detector for Symbol Timing Recovery of&amp;lt;tex&amp;gt;$M$&amp;lt;/tex&amp;gt;-PSK Signals

In this letter, we propose a modified version of the Gardner detector for symbol timing recovery of M-ary phase-shift keying (M-PSK) signals. Simulation results show that the proposed modification leads to significant performance improvement when M-PSK signals are highly bandlimited and M is small. Specifically, the reduction in the level of self-noise due to the modification amounts to 10.7 dB for quaternary phase-shift keying signals with the rolloff factor of 0.25 and the normalized noise-equivalent loop bandwidth of 0.005. In terms of computational complexity involved, the proposed method has an advantage over the known self-noise reduction methods for M-PSK signals with small M.

Maximum-likelihood block-size detection for MPSK signaling

In some communications systems, it is required to estimate the size of the received frame or block blindly; that is, using only the received frame. An example where such a problem arises is third-generation wideband code division multiple access universal mobile terrestrial systems (WCDMA UMTS), where it is sometimes required to perform a blind transport format detection. We propose and evaluate a novel method for block-size detection for M-ary phase-shift keying (MPSK) signaling based on the maximum-likelihood principle. Either the method we propose can be used to estimate the block size directly when the operating signal-to-noise ratio (SNR) yields a satisfactory "one-shot" detection error probability or it can be used as a good "coarse" estimate of the block size. In the latter, a good initial guess of only few potential block-size candidates is obtained instead of scanning all possible candidates and then a more accurate detection technique, however more complex, is used to narrow down the number of potential candidates to only one successful candidate.

A Software Defined Radio Platform with Direct Conversion: SOPRANO

In this paper, a new software defined radio platform with direct conversion is introduced. The platform is named SOPRANO, which stands for Software Programmable and Hardware Reconfigurable Architecture for Network. Main features of SOPRANO include a high-level design methodology for digital circuits, direct conversion based on six-port technology, and novel digital signal processing algorithms for multi-band and multi-mode operation. The first prototype of the SOPRANO platform has been built and was able to receive M-ary PSK (Phase Shift Keying) and QAM (Quadrature Amplitude Modulation) signals, with two different carrier frequencies at 2.45 GHz and 5.25 GHz, by changing signal-processing software.