Automatic Modulation Recognition for Phase Shift Keying Signals With Compressive Measurements

Differential phase-shift keying (DPSK) has been widely implemented and developed in high-speed optical communication systems. The low error rate detection at high access rate is one of the considerable issues in practical engineering application. Balanced detection based on fiber Mach-Zehnder delay interferometer (MZDI) is the typical optical DPSK signal detecting method. It requires that the free spectrum range (FSR) of the MZDI equals the reciprocal of symbol period of the DPSK signal. For the reasons of ambient temperature variation and nonlinear phase noise, a dynamic frequency offset always exists between the FSR and the reciprocal of symbol period. That may introduce some optical signal-to-noise ratio (OSNR) costs and fault detections. Therefore, it is significant to inhibit the frequency offset on DPSK detection. In this paper, firstly, we discuss the effects of frequency offset on DPSK detection, and realize the conclusion that frequency offset is virtually equivalent to an additional phase difference between adjacent symbols. Secondly, through simulation, we analyze the feasibility of DPSK detection in the presence of a definite range of frequency offset, and present the quantitative computation of effective coverage, duty cycle, and optimal sampling time of symbol interference. Some issues which should be considered in practical implementation are also discussed. Finally, according to the relationship among phase difference, temperature and voltage, we propose a phase difference compensation scheme which can automatically adjust the voltage for optimal detections, and dynamically track the changing of ambient temperature and nonlinear phase noise. Furthermore, we ascertain the performance of the voltage requested for implementing the scheme. The scheme can be also developed to quadrature phase-shift keying (QPSK) and differential QPSK (DQPSK) modulation situations.

Performance Analysis of Different Phase Shift Keying Modulation Schemes in Aeronautical Channels

Shaped offset quadrature phase shift keying (SOQPSK) modulation scheme and its application in optical wavelength-division multiplexed (DWDM) transmission

We propose and experimentally demonstrate generation of optical carrier suppressed-optical differential phase-shift keying (OCS-oDPSK) modulation format in radio-over-fiber (RoF) systems using one single-drive Mach-Zehnder modulator (MZM). This scheme realizes up-conversion of baseband data for downlink wireless service delivery, generation of remote local oscillator (LO) signal for down-conversion of uplink radio frequency (RF) signal, and remodulation of down-converted uplink data, thus lowering the cost of base stations (BSs) in full-duplex RoF systems. The proposed scheme is expected to be simple and compact due to the use of a single MZM. Furthermore, the OCS-oDPSK generation principle is extended to obtain an OCS-optical differential quadrature phase-shift keying (OCS-oDQPSK) signal by employing a dual-parallel MZM (DPMZM), which is useful to deliver multiple wireless services on the same RF carrier.

The present paper deals with design and development of a generalized parametrizable modulator (GPM) that can perform Gaussian minimum shift keying (GMSK) modulation and Quadrature Phase Shift Keying (QPSK) modulation in a reconfigurable baseband modulator for software defined radio (SDR) architecture. GMSK is the underlying modulation scheme for the Global System for mobile (GSM) standard, while QPSK technique is the basic modulation scheme for Code Division Multiple Access (CDMA) standard. Although GMSK is an inherently non-linear modulation technique, the present work uses a linearly approximated GMSK technique to take the advantage of the simplicity of the filter structure. The normalised error in amplitude as a function of modulation index and bandwidth time product has been simulated. The proposed GPM is capable of working at a maximum data rate of 13.75 Mbps, thus satisfying the requirements of almost all 2G and 3G air interface standards. The GPM can perform QPSK using four pulse shaping filters, two Raised Cosine (RC) filters and two Root Raised Cosine (RRC) filters. The proposed GPM architecture is implemented on a Spartan 3E starter kit.

The significance of digital communication has been well accepted all over the world. It has been widely used in wireless networks like satellite communication, and 4G and 5G technologies as it provides high data connectivity and efficiency. For long-distance transmission and reception of signals, maintaining the signal quality is very important and therefore an efficient modulation and demodulation scheme is required. In this paper, the quadrature phase shift keying (QPSK) modulation scheme is being presented. Its several advantages over other digital modulation techniques made it one of the best forms of digital modulation. The concept of software-defined radio has been used as a test bed for implementing QPSK modulation. Simulation of QPSK modulation and demodulation process is performed in Laboratory Virtual Instrument Engineering Workbench software, and the digital transmission and reception of signals are done through Universal Software Radio Peripheral. The signal experiences sampling, quantization, filtering, encoding, modulation, demodulation, decoding, with and without the addition of additive white Gaussian noise on the graphical interface of NI LabVIEW. Several investigations have been done on digital modulation, but they are covered entirely on simulation in any software. In this paper along with the implementation of modulation and demodulation part, the transmission and reception of the signal are also performed using USRP.

This paper presents recent progress toward the realization of ultrahigh-speed coherent optical transmission with a single-channel bit rate of more than 1 Tbit/s using ultrashort pulse technology and an advanced modulation format. We first describe Tbit/s optical time-division multiplexing (OTDM) transmission employing differential binary or quadrature phase shift keying. We present our recent demonstrations of single-polarization 640-Gb/s differential phase-shift keying and 1.28-Tb/s differential quadrature phase-shift keying transmissions over 525 km, which employ an ultrafast optical Fourier transformation technique. We then focus on coherent optical transmission using quadrature amplitude modulation (QAM) with a multiplicity of 512 that enables us to achieve an ultrahigh spectral efficiency of more than 10 b/s/Hz. Finally, we demonstrate a novel ultrahigh-speed, spectrally efficient coherent pulse transmission combining OTDM and QAM. A 400 Gb/s, 32 RZ/QAM signal was successfully transmitted over 225 km on a single carrier at 10 Gsymbol/s × 4-OTDM.

Low voltage, in-home power-line communications (PLC) networks allow direct communication between smart meters (SM) and in-home devices (IHD). In order to minimize security issues, in many deployment scenarios transmission takes place only towards the IHD to display consumption data, with no backwards channel. As a result, channel estimation is difficult and it is necessary to use robust transmission techniques to mitigate the effect of the impulsive noise within the PLC channel. Performance of such system must be evaluated by taking into account realistic interference and channel models for a broad range of configurations. In this work we focus on performance in terms of bit error rate (BER) of a narrowband PLC (NB-PLC) operating in the CENELEC-C band (125–140 kHz) taking into account realistic noise models. Our system is based on binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) modulation.

In this research study, different Peak Average Power Ratio (PAPR) based reduction techniques, namely, A-Law companding, µ-Law companding, Clipping & Filtering and Clipping are analyzed for Filter Band Multi-Carrier (FBMC) with different transmission systems such as Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 64-QPSK and 64-Quadrature Amplitude Modulation. It is estimated that the PAPR reduction can benefit by using clipping technique in FBMC.

This paper presents analysis and performance evaluation results for several neural-net based receiver structures which effectively combat additive channel interference, such as co-channel interference (CCI) and adjacent channel interference (ACI). Although the idea of employing neural net based receivers for interference channels is not new, the novel technical contributions of the authors' paper can be summarized as follows. (i) Propose, analyze and evaluate a training algorithm for Nyquist filtered single- and multi-amplitude signals which is based upon a novel non-uniform signal sampling technique. (ii) Propose and evaluate neural net structures employing a novel non-linear activation function for the detection of multi-amplitude signals. (iii) Present novel bit error rate (BER) performance evaluation results for coherent and noncoherent single- and multi-amplitude signals, including binary phase shift keying (BPSK), quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM), operated in generalized CCI and ACI channels. The authors' research has demonstrated that, as compared to more conventional detection techniques, the proposed neural net receivers provide significant performance improvements in CCI and/or ACI channels. Their tolerance for inaccuracies in symbol timing synchronization also makes them good candidates for practical modem implementation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The typical subcarrier modulation schemes used in orthogonal frequency division multiplexing (OFDM) system includes; binary phase shift keying (BPSK), quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM). This paper analyses the performance of OFDM system that uses various number of modulation QAM constellation points over various fading channels. Simulation is done for various numbers of QAM (8 to 64-points) and with various Doppler frequency values (5 to 500 Hz) over flat and frequency selective fading channels. Results show that the best performance of OFDM system is with the number of QAM of 8 and maximum Doppler shift (MDS) of 5 Hz at all channels.

Selected Mapping (SLM) is the assuring peak to average power reduction (PAPR) technique for OFDM system. But this technique undergoes a very complex process for finding optimum phase sequence for the reduction of PAPR. Hence, in this paper highly optimized phases are derived and analyzed from proposed algorithm for selected mapping using several modulation schemes such as binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 8-PSK, 64-PSK, and 64-quadrature amplitude modulation (QAM). The simulation results are performed in MATLAB using complementary cumulative distribution function (CCDF) which clearly depicts that the performance of proposed schemes HIGHLY-OPTIMIZED-SLM2 (HOS-2) and HIGHLY-OPTIMIZED-SLM1 (HOS-1) is remarkable under 64-QAM because gain achieved are 2.95 dB, 1.35 dB respectively as compared with original OFDM system.

Background/Objectives: Tremendous growth in the mobile communication services in this technology driven era has made possible for the people to exchange information (data, voice or image) with each other while they are on the move. These wireless systems have brought a revolution in the current market for their high data rates and performance enhanced features. Methods/Statistical Analysis: One of the key issues affecting the performance of a wireless channel is the random variations in the signal strength which may be resulted due to some obstructions like buildings, trees, etc. or due to the movement of the mobile user. This leads to stochastic behavior of the radio channel.. A highly faded Two-Wave with Diffuse Power (TWDP) environment is discussed along with hybrid diversity combining technique. The effectiveness of this scheme is further evaluated by analyzing the system performance in terms of Bit Error Rate (BER) vs Signal to Noise Ratio (SNR). Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK) modulation techniques were employed. Findings: It has been shown clearly that TWDP forms the poorer link when compared with other fading channels as BER is higher in this case. Moreover, TWDP fading environment can serve as the worst case scenario in wireless communication system. Also it has been shown as the diversity order increases system’s performance is improved in terms of BER and reduction in SNR requirement to achieve a constant BER value. Application/Improvement: This paper presents the need to obtain a clear perception of channel characteristics and to model a system for combating fading and improving the system performance by considering a TWDP fading channel instead of Rayleigh channel while designing a wireless communication system in worst channel conditions..

The demand for a high bit rate data transmission in space applications has been rapidly increasing especially where one deals with Earth observing missions. In a multi-carrier operation, the problem of interference between carrier spectra appears. Several modulation techniques for digital transmission have recently been investigated for the purpose of achieving narrow signal spectra with power concentrated within a given bandwidth. While designing a communication system, particularly a satellite communication system, special attention is needed to use the primary resources namely, the transmitted power and channel bandwidth. Space communication links are both bandwidth- and power-limited. The quadrature phase shift keying (QPSK) modulation scheme is best suited for satellite communication since bandwidth and power required is optimum. In this paper, some observations on QPSK spectral spikes and the methods to eliminate them as well as pulse shaping circuits to improve spectrum bandwidth are presented.

This paper analyzes the influence of haze on the performance of ground space optical communication (GSOC). Firstly, the scattering model of haze aerosol is established based on the coated scattering theory of Christian Matzler. Then the fitting relationship between atmospheric visibility V and PM 2.5 is obtained according to the Meteorological Bureau of Beijing. In order to calculate the attenuation coefficient, the relationship between spectral distribution of aerosol particles and PM 2.5 Index is derived. Finally, the effect of haze on GSOC with different detectors and modulation modes are discussed. The result shows that with the increase of PM 2.5 Index, the received optical power, sign-to-noise (SNR) and channel capacity (CAP) decrease rapidly, and bit error rate (BER) increases rapidly. In terms of wavelength selection, under the same detector and modulation mode, the effect of haze on the GSOC of the 0.86um laser is greater than that of the 1.55um laser. In the modulation method, the use of Binary Phase Shift Keying (BPSK) modulation is better than the use of Quadrature Phase Shift Keying (QPSK) in order to reduce the BER, while the worst modulation is to use On-Off Keying (OOK). When the sensitivity of the detector is -35 dBm，the value of PM 2.5 corresponding to 1.55um is not higher than 557, and the value of PM 2.5 corresponding to 0.86um is not higher than 548.