M-PSK Modulation Scheme Research Articles

Developing Laboratory Experiments to teach Undergraduate Engineering Students Multi-User Massive MIMO Technology for 5G Cellular Networks

An effective method of facilitating student learning in a laboratory environment is “practice by doing”. The study of modules related to signal-processing for digital communications requires deep mathematical and theoretical foundations but the practice goal is not really emphasized in the undergraduate curriculum at the University of Mauritius. This causes the students to lose interest in the corresponding modules resulting in high rate of failures. In this work, we propose to develop laboratory experiments with a view to bridge the gap between theoretical and practical aspects in the field of Massive Multiple-Input Multiple-Output (MIMO) systems for 5G cellular networks. Various laboratory scenarios are set up that consider a Maximum Ratio Combining (MRC) receiver in the uplink with an uncorrelated Rayleigh fading channel. Moreover, from a signal processing perspective to enhance the student’s understanding, we analyze the efficiency and error performance of Massive MIMO systems with MPSK and MQAM modulation schemes as well as perfect and imperfect channel estimates. The leading industry software package MATLAB R2022 is used to develop all laboratory experiments and the codes are elaborated in this analysis. Data collected from the experiments are used to generate spectral efficiency and error performance curves which can be used for future research. The findings underscore the significance of accounting for both scenarios and illuminate promising avenues for future research in the realm of massive MIMO education and learning. The assimilation of MATLAB® flowcharts for each MRC receiver, MPSK, and MQAM with perfect and imperfect Channel State Information (CSI) adds further depth to the study, ensuring a comprehensive understanding of the intricacies of massive MIMO systems. Ultimately, this contribution helps in the nurturing of expertise such that future generations of wireless communication pioneers can be inspired.

An Analytical Reliability Performance Assessment of Cell-Free Massive MIMO Systems for 5G and Beyond Cellular Networks

In today‟s realm, the 5G cellular networks offer a new era of fully digital environment by connecting people anywhere anytime. This era requires inspiring demands to the networks in terms of spectral and energy efficiencies, low-latency and ultra-reliable communications. A major development to deal with these unparalleled demands is the introduction of Cell- Free Massive MIMO (CF mMIMO) systems to the cellular network. In recent years, mathematical foundations have been laid for a CF mMIMO communication system to evaluate the spectral and energy efficiencies given the number of access points. Various existing literatures have adopted mathematical models to formulate closed-form expressions for these efficiencies using uncorrelated Rayleigh fading for simple linear processing detectors. In this paper, we try to address a compelling and interesting question which has not received much attention lately. The question is how to evaluate the reliability of a connected user terminal in both a CF mMIMO and conventional mMIMO system? We answer this question by first analyzing the signal models for both systems assuming exact channel estimates and consider an uncorrelated Rayleigh fading channel model. The exact Bit Error Rate, as a reliability assessment, in closed-form are then derived based on strong mathematical foundations, which are simple to numerically evaluate in Matlab R2022, for MPSK and MQAM modulation schemes. The mathematical models presented in this work can be used in 5G and Beyond 5G networks to evaluate the distributions of error rates for a user given the number of Access points or Base Station antennas and modulation scheme. Machine Learning algorithms can be applied to the analytical expressions with a view to predict the error performance of a user terminal given the fading characteristic of the propagation environmen

ALAMOUTI SPACE-TIME CODING FOR VEHICULAR COMMUNICATIONS IN THE PRESENCE OF CHANNEL ESTIMATION ERRORS

In this paper, the error performance of the Alamouti space-time coding (STC) scheme is investigated for vehicle-to-vehicle (V2V) communication systems over imperfect cascaded fading channels. In vehicular communication systems, perfect knowledge of the channel state information is not available to the users at all times due to the rapid movement of communicating vehicles and fast change of the rich scattering environment which makes the fading effects in wireless channels more severe. Therefore, in the analysis, we consider the erroneous estimation of the channel gain, which is more realistic for practical scenarios. For this purpose, we first derive the moment-generation function (MGF) of the channel fading coefficient with estimation error in the case of the cascaded Nakagami-m fading conditions. Then, using the MGF, we obtain the closed-form symbol-error-rate (SER) expressions of Alamouti STC with two transmitting and L receiving antennas for the M-PSK and M-QAM modulation schemes. Then, the exact ergodic capacity expression is derived for the proposed system. Furthermore, the analytical results are verified through Monte-Carlo simulations. Numerical results show that the SER performance of V2V communication systems can be improved significantly by using Alamouti STC even in case of harsh fading conditions and full channel-state information is not available due to estimation errors.

Pairwise Error Probability Analysis of SM-MIMO system employing k – μ Fading Channel

This paper analyzes the performance of spatially modulated (SM) multiple-input-multiple-output (MIMO) system using k – μ fading channel. The Pairwise error probability (PEP) analysis of SM-MIMO over k – μ fading channel considering M-PSK modulation scheme has been done. Further, the analysis is done for different values of k and μ in k – μ fading channel.The SMMIMO PEP expressions for k – μ fading channel considering M-PSK modulation scheme has been derived. The Performance comparison of simulation results has been done for k – μ fading channels.The performance comparison of PEP has been done for M-PSK using k – μ fading channel.

Classification of M-QAM and M-PSK signals using genetic programming (GP)

With the popularity of software-defined radio and cognitive radio-technologies in wireless communication, radio frequency devices have to adapt to changing conditions and adjust its transmitting parameters such as transmitting power, operating frequency, and modulation schemes. Thus, automatic modulation classification becomes an essential feature for such scenarios where the receiver has a little or no knowledge about the transmitter parameters. This paper presents kth nearest neighbor (KNN)-based classification of M-QAM and M-PSK modulation schemes using higher-order cumulants as input features set. Genetic programming is used to enhance the performance of the KNN classifier by creating super features from the data set. Simulation result shows improved accuracy at comparatively lower signal-to-noise ratio for all the considered modulations.

Intrinsic Secrecy of EGT and MRT Precoders for Proper and Improper Modulations

This paper makes an information theoretical analysis of the intrinsic secrecy level of M-QAM and M-PSK modulation schemes considering the use of equal gain transmission and maximum ratio transmission precoding techniques. In addition to the analysis of the conventional proper M-QAM and M-PSK constellations, a recently proposed family of improper versions of the M-QAM and M-PSK modulation schemes is also evaluated. With the exception of proper M-PSK, which verifies always full secrecy for the considered precoders, the main results show that for low order constellations, the amount of intrinsic secrecy provided by the combination of the precoder and modulation scheme is significant and, therefore, can be exploited in the design of a full secrecy solution. The theoretical derivations provided in this paper can be directly applied to quantify the minimal entropy that a secret key must have to fully secure the exchange of information for these transmission schemes.

Blind signal modulation recognition through clustering analysis of constellation signature

Modulation classification using OPTICS clustering algorithm has been proposed.Algorithm is reliably classifying 4ASK, 8ASK, BPSK, QPSK and 8QAM above 9dB SNR.Classification is unsupervised and generalized for any orders ASK, PSK and QAM.Algorithm is implemented and tested on real time RF signal using labVIEW. Automatic recognition of digital modulation schemes is becoming an active research area in many covert operations. It has many military applications where surveillance and electronic warfare requires a type of modulation in intercepted signal to prepare jamming signals. Most of the approaches are based on modulated signal's component, but the modulation type can be best identified with the use of constellation diagram. The proposed technique is able to recognize M-QAM, M-ASK, and M-PSK modulation scheme in Additive White Gaussian Noise (AWGN) environment. As the constellation points form clusters in the I-Q plane, the order of the modulation can be obtained by estimating the correct number of clusters, which is calculated by OPTICS algorithm. The least square error has been calculated using linear regression from the obtained constellation points, to identify either ASK or PSK and QAM. The error is least for ASK which differentiates ASK from PSK and QAM. To identify between the PSK and QAM, k-means clustering is employed to find the number of centroids equal to order of modulation estimated by OPTICS. With the difference in maximum and minimum absolute value of the centroids, PSK or QAM is recognized. The proposed method shows an improvement in the classification accuracy which reaches 100% using 1024 symbols at 20dB compared to 98.89%, 98.05%, and 98% when using more complex classifiers like Support Vector Machine, Naive Bayes Classifier, KNN respectively. The method used is unsupervised whereas most of the methods in the literature require training phase to set the thresholds or weights for final model to detect modulation type. This algorithm is also implemented in LabVIEW, and tested on real-time signals. An intelligent system is made which does not require any knowledge of symbol rate, carrier frequency, and any training phase to set thresholds, and detects the type of modulation blindly in real time. Modulated RF signals are generated by NI PXIe-5673 (RF transmitter). NI PXI 5600 is used to downconvert RF signal and NI PXI-5142 (100 MS/s OSP digitizer) is used to sample the downverted signal.

High‐performance VLSI architectures for M‐PSK modems

M-PSK (phase shift keying) modulation schemes are used in many high-speed applications like satellite communication, as they are more bandwidth and power efficient compared with other schemes. This study presents very large scale integrated circuits (VLSI) architectures for modulators and demodulators of quadrature phase shift keying (QPSK), 8PSK and 16PSK systems, based on the principle of direct digital synthesis. The proposed modulators do not use any multiplier in contrast to the conventional modulators and hence they are relatively fast and area efficient. Based on the coherent detection technique, this study proposes new demodulation algorithms for 8PSK and 16PSK systems which can be implemented both in analogue and digital domains. This study also presents VLSI architectures for all the proposed algorithms. The proposed architectures are described in Verilog and implemented on Xilinx field programmable gate arrays (FPGAs). The simulation results verify their functional validity and implementation results show the suitability of the proposed architectures for satellite communications.

Performance Improvement of 4x4 Extended Alamouti Scheme with Implementation of Eigen Beamforming Technique

This paper highlights on the error performance improvement of 4 ×4 Extended Alamouti Scheme with implementation of Eigen-Beamforming technique. In a MIMO communication system, the beamforming technique improves the Signal-toNoise Ratio (SNR) and/or Signal-to-Interference-plus-Noise ratio. So, to get advantage of beamforming technique, 4x4 Extended Alamouti Scheme is implemented with Eigen beamforming technique. This combined technique comprises of channel state information which is fed back to the transmitter side in order to achieve proper error performance as compared to Extended Alamouti Scheme without Beamforming. This proposed scheme provides array gain by increasing the bit-error-rate (BER) performance for different wireless communication channels and M-PSK modulation scheme.

Performance Evaluation of LT Coded MPSK Modulation Schemes in the Presence of Doppler Frequency Shift

Performance Evaluation of LT Coded MPSK Modulation Schemes in the Presence of Doppler Frequency Shift

Variable-rate M-PSK communications without channel amplitude estimation

Channel estimation at the receiver side is essential to adaptive modulation schemes, prohibiting low complexity systems from using variable rate and/or variable power transmissions. Towards providing a solution to this problem, we introduce a variable-rate (VR) M-PSK modulation scheme, for communications over fading channels, in the absence of channel gain estimation at the receiver. The choice of the constellation size is based on the signal-plus-noise (S+N) sampling value rather than on the signal-to-noise ratio (S/N). It is analytically shown that S+N can serve as an attractive simpler criterion, alternative to S/N, for determining the modulation order in VR systems. In this way, low complexity transceivers can use VR transmissions in order to increase their spectral efficiency under an error performance constraint. As an application, we utilize the proposed VR modulation scheme in equal gain combining (EGC) diversity receivers.

A New Space-Time Multiple Trellis Coded Modulation Scheme Using Transmit Symbol Phase Rotation

Space-time multiple trellis coded modulation (ST-MTCM) has been introduced in order to achieve maximum transmit diversity gain and larger coding gain with the existence of parallel paths. In our previous research, we designed a new coded modulation scheme for ST-MTCM which simultaneously maximizes the coding gain and diversity gain utilizing Hadamard Matrix giving the maximum determinant. This scheme, however, cannot achieve full transmit rate. In this paper, we extend our research so as to achieve full rate transmission as well as maximum coding and diversity gain. In addition, Super-Orthogonal Space-Time Trellis Code (SO-STTC) is well known for its high coding gain, full diversity gain and full transmit rate. Even though our proposed scheme is essentially the same as SO-STTC, we show in this paper that our proposed code design is different from SO-STTC, and achieves better performance. Our proposed code design utilizes transmit symbol phase rotation at a certain time slot so as to avoid same path transition in trellis, which occurs with conventional SO-STTC scheme. We design codes with different way of phase rotation for different MPSK modulation scheme, and simulation results show the improvements of our proposed codes for MPSK modulation with different number of states.

Scenario driven evaluation and interference mitigation proposals for Bluetooth and high data rate Bluetooth enabled consumer electronic devices

Previous research has focussed on residential coverage and achievable data rates using the Bluetooth personal area network (PAN) standard. To meet the bit rate needs of future consumer electronics devices, M-PSK modulation schemes have been proposed as likely candidates for high data rate extensions to Bluetooth. This paper investigates the effects of interference occurring between high data rate time-bounded and non-time-bounded Bluetooth enabled consumer electronic devices. Frequency hopping selection kernels for both the 79-hop and the 23-hop systems in Bluetooth were implemented in software. Using this model, collision statistics were obtained between a wanted Bluetooth user (in a piconet) and interferers (Bluetooth users in different piconets) operating under typical scenarios that were constructed within the test environment. These scenarios featured piconets operating in an office environment in both synchronous and asynchronous modes and with typical up and downlink loading factors. A detailed link level physical layer simulation was used to obtain packet error rate performance based on the collision statistics obtained. Finally, a state-of-the-art indoor space-time propagation modelling tool was used to analyse the data throughput performance capabilities for Bluetooth data medium (DM) rate and data high (DH) rate packets. Results highlight a clear need to mitigate interference by employing synchronous communication in future Bluetooth evolution networks.

Non—data—aided ML carrier frequency and phase synchronization in OFDM systems

AbstractIn this paper non—data—aided(NDA), maximum likelihood(ML) algorithms are derived for the carrier frequency and phase offset, separately, for OFDM systems employing M—PSK modulation scheme. NDA ML estimation algorithm for frequency offset estimation exploits the redundant information contained in the cyclic prefix proceeding the OFDM symbols, thus reducing the need for pilots. Its mean—squared performance is obtained analytically and compared with simulation results. It is observed that the resulting algorithm generates very accurate estimation even when the offset is high. It is also shown that the frequency estimator may be used in a tracking mode. The ML algorithm derived for the carrier phase estimation is also a non—data—aided(NDA) and maximizes the low SNR limit of the likelihood function averaged over M—PSK signal constellation. It is shown that for sufficiently small SNR the ML phase estimator obtained reduces to the familiar M/th order power synchronizer which belongs to the class of NDA feedforward carrier synchronizers introduced earlier in the literature. Its mean—squared performance is obtained analytically and compared with simulation results. We observe that the resulting algorithm generates very accurate estimation even when the phase offset is high, that the self noise is absent and the performance of the algorithm is basically the same as die Cramer—Rao bound for moderate to high SNR. Finally we note mat me error variance derived for the mean—squared performance of this NDA ML synchronizer is an extension of the approximate variance formula appeared in Reference 20,equation(14) for M—PSK.

Compact 38 GHz MMIC balanced vector modulators employing GaAs/InGaP HBTs

The design and performance of a 38 GHz balanced I-Q type vector modulator, using HBTs as switching elements, is presented. The MMIC chip can be employed to implement direct M-PSK and M-QAM modulation schemes in order to reduce hardware complexity and cost. A novel miniature microstrip coupler geometry can be employed to further minimise the modulator's size, yielding a circuit which only measures 1.4 × 1.2 mm2. The balancing topology can be used to remove the parasitics of the HBTs resulting in near perfect constellations, and the compact layout can greatly reduce the cost of expensive transmitter chip area.