AWGN Channel Model Research Articles

An Efficient Multiplexing Technique For 5G Wireless Network: Analysis and Selection

The 5G cellular communication technology is intended to base on the present Long-TermEvolution (LTE) 4G networks with adopted features. Features of low power consumption and theconstant power level should be the major requirement for an efficient channel allocation method. In thisresearch work, an analysis was performed on multiplexing techniques: Orthogonal Frequency DivisionMultiplexing (OFDM), Generalized Frequency Division Multiplexing (GFDM), Universal FilteredMulticarrier (UFMC) and Filter-Bank Multicarrier (FBMC). Smooth power level had been analyzedaccording to Power Spectral Density (PSD) function vs normalized frequency using AWGN channelmodel. The simulation was done by MATLAB 2019 Simulink software for OFDM and GFDM that werefurther compared to existing results of UFMC and FBMC multiplexing techniques. Calculated power forOFDM and GFDM were 32.1mW and 40.23 µW respectively. Comparative results showed the bettersmooth power spectrum, micro-watt power consumption and better hardware configuration for GFDM.That’s why GFDM channel allocation method selection is one step ahead for the next generationmultiplexing technique

Modular Link Level Simulator for the Physical Layer of Beyond 5G Wireless Communication Systems

AbstractThe low THz band is a promising candidate to enable data rates of up to 1 Tbit/s. To develop suitable communications systems, novel simulation approaches are needed that account for the specifics of the evolving technology. This article presents a modular link level simulator for the physical layer of beyond‐5G and 6G wireless communication systems in the THz range. The simulator, that is oriented toward the IEEE Std 802.15.3d‐2017 is contrasted to the state of the art of physical layer simulation tools. Its concept and basic building blocks are presented and the simulator is validated by channel simulations considering an AWGN channel model. Moreover, it is applied to a top‐of‐rack scenario in a wirelessly augmented data center. Different parameter sets are compared showing that a LOS condition and sufficient transmit power are a prerequisite in order to profit from the large bandwidth in the low THz range. The extensive data set of simulation results serves as input for future studies with higher layer simulation tools.

Exploring and Experimenting With Shaping Designs for Next-Generation Optical Communications

A class of circular 64-QAM that combines 'geometric' and 'probabilistic' shaping aspects is presented. It is compared to square 64-QAM in back-to-back, single-channel, and WDM transmission experiments. First, for the linear AWGN channel model, it permits to operate close to the Shannon limits for a wide range of signal-to-noise ratios. Second, WDM simulations over several hundreds of kilometers show that the obtained signal-to-noise ratios are equivalent to - or slightly exceed - those of probabilistic shaped 64-QAM. Third, for real-life validation purpose, an experimental comparison with unshaped 64-QAM is performed where 28% distance gains are recorded when using 19 channels at 54.2 GBd. This again is in line - or slightly exceeds - the gains generally obtained with probabilistic shaping. Depending upon implementation requirements (core forward-error correcting scheme for example), the investigated modulation schemes may be key alternatives for next-generation optical systems.

Performance analysis and improvement of machine learning algorithms for automatic modulation recognition over Rayleigh fading channels

Automatic modulation recognition (AMR) is becoming more important because it is usable in advanced general-purpose communication such as, cognitive radio, as well as, specific applications. Therefore, developments should be made for widely used modulation types; machine learning techniques should be employed for this problem. In this study, we have evaluated performances of different machine learning algorithms for AMR. Specifically, we have evaluated performances of artificial neural networks, support vector machines, random forest tree, k-nearest neighbor, Hoeffding tree, logistic regression, Naive Bayes and Gradient Boosted Regression Tree methods to obtain comparative results. The most preferred feature extraction methods in the literature have been used for a set of modulation types for general-purpose communication. We have considered AWGN and Rayleigh channel models evaluating their recognition performance as well as having made recognition performance improvement over Rayleigh for low SNR values using the reception diversity technique. We have compared their recognition performance in the accuracy metric, and plotted them as well. Furthermore, we have served confusion matrices for some particular experiments.

Blind FrFT-OFDM signal parameters estimation for underlay cognitive radio based on second-order cyclo-stationarity feature

Fractional Fourier transform (FrFT) OFDM scheme has been proposed previously in order to alleviate the problem of high peak to average power ratio (PAPR) of OFDM and its immunity against inter carrier interference. The cyclo-stationarity property of FrFT-OFDM is often neglected in the literature. In this paper, this missing analysis is provided and a blind algorithm for FrFT-OFDM signal parameters estimation is proposed. Novel mathematical formulas for the autocorrelation function of the FrFT-OFDM signal over both AWGN and fading channels are derived. These mathematical formulas show that the FrFT-OFDM signal has a cyclo-stationarity property. Also, novel mathematical formulas are derived for cyclic autocorrelation function of the FrFT-OFDM signal over both AWGN and fading channel models. Simulation results for the cyclic autocorrelation function show that signal detection and parameters estimation based on FrFT-OFDM cyclo-stationarity are feasible. The case of underlay cognitive radio is also investigated.

Multiple input multiple output CDSK chaotic communication system and its performance analysis

This paper propose a novel noncoherent chaotic communication scheme named multiple-input multiple-output correlation- delay-shift- keying (MIMO-CDSK). In this scheme, multiple antennas are employed to strengthen the robustness in transmission, and to get more diversity gain. The bit error rate (BER) of the MIMO-CDSK is studied analytically in AWGN channel model and multipath fading channel model. The theory and simulation results show that, the performance gain can be obtained with multiple antennas allocated in the transmitter and receiver. Moreover, it is observed that MIMO-CDSK system can effectively reduce the multipath interference.

Symbol Synchronization for OFDM Receivers with FFT Transport Delay Compensation

This paper proposes a new blind approach for time synchronization of orthogonal frequency division multiplexing (OFDM) receivers (RX). It is largely known that the OFDM technique has been successfully applied to a wide variety of digital communications systems over the past several years — IEEE 802.16 WiMax, 3GPP-LTE, IEEE 802.22, DVB T/H, ISDB-T, to name a few. We focus on the synchronization for the ISDB-T digital television system, currently adopted by several South American countries. The proposed approach uses the coarse synchronization to estimate the initial time reference and then, the fine synchronization keeps tracking the transmitter (TX) time reference. The innovation on the proposed approach regards to the closed loop control stabilization of the fine synchronization. It uses a smith predictor and a differential estimator, which estimates the difference between TX and RX clock frequencies. The proposed method allows the RX to track the TX time reference with high precision ([Formula: see text] sample fraction). Thus, the carriers phase rotation issue due to incorrect time reference is minimized, and it does not affect the proper RX IQ symbols demodulation process. The RX internal time reference is adjusted based on pilot symbols, called scattered pilots (SPs) in the context of the ISDB-T standard, which are inserted in the frequency domain at the inverse fast Fourier transform (IFFT) input in the TX. The averaged progressive phase rotation of the received SPs at the fast Fourier transform (FFT) output is used to compute the time misalignment. This misalignment is used to adjust the RX fine time synchronism. Furthermore, the proposed method has been implemented in an ISDB-T RX. The FPGA-based receiver has been evaluated over several multipath, Doppler and AWGN channel models.

Performance Improvement of Coded OFDM Communication System in AWGN Channel

orthogonal Frequency Division Multiplexing) is a basic element in the 4G mobile system. The OFDM performance can be improved using the channel coding. The channel coding is a class of signal transformations designed to improve communication system performance. The work presented in this paper discusses the performance improvement of OFDM communication system using different channel coding techniques through AWGN channel model. These coding techniques include Reed Solomon coding, Convolutional coding, Concatenated coding (by combining Reed Solomon with Convolutional), and Interleaved concatenated coding techniques. Besides, a new algorithm produced to choose a good convolutional encoder design for a certain rate and memory registers.

Evaluation of Kolmogorov - Smirnov test and energy detector techniques for cooperative spectrum sensing in real channel conditions

The cognitive radio technology allows solving one of the main issues of current wireless communication technologies, namely a deficit of vacant spectrum. A dynamic spectrum access used in the cognitive radio networks (CRN) gives an ability to access an unused spectrum in real time. Cooperative spectrum sensing is the most effective method for spectrum holes detecting. It combines sensing information of multiple cognitive radio users. In this paper, an experimental evaluation of spectrum sensing methods based on the Kolmogorov - Smirnov statistical test and Energy Detector using the Universal Software Radio Peripheral (USRP) devices synchronized through a MIMO cable and with further processing in the GNU Radio and Matlab software are presented. Three hard decision fusion schemes are analyzed. Simulation comparison between these rules is presented via Receiver Operating Characteristic (ROC) curves. The influence of real channel with interferences is compared in contrast to commonly assumed AWGN channel model of vacant channel noise.

Network Coded Modulation for Two Way Relay Networks

Modern wireless networks use cooperative relaying to expand its coverage area. Wireless relaying allows mobile terminals toparticipate in transmission even when these terminals are not being the initial source or final destination. This can be achieved in differentways ranging from simple conventional relaying to more sophisticated coding at terminal and relay nodes to improve transmissionperformance. The proposed work here studied such system by simulating different coding techniques to be used in two way relay networkcoding (TWRC). Some of these techniques were previously proposed to improve transmission performance in conventional datacommunication systems. BER performance of different arrangements of coding and relaying schemes are evaluated using computersimulation tests. Ideal AWGN channel model and standard wireless channel models for wireless networks are considered in the simulationtests. The results have been shown that coding schemes such as Trellis Coded Modulation (TCM) and Repeat Accumulate (RA) codes aremore suitable in two way relaying networks. Over AWGN, TCM-8PSK improves BER performance by at least 2 dB at high SNR fordifferent relaying arrangements. For fading channels, this advantage is slightly reduced. Regenerative repeating at relay node seems to be apromising arrangement. It seems that there is no sense in using RA codes over fading channels due to its poor performance and relativelylower speed caused by repetitions.

An Efficient Low Complexity Transform for DCT-OFDM Based Wireless Communication System

A precise method for the performance of a new DCT based OFDM system using a low complexity T-transform that combines the WHT and the DCT into a single fast orthonormal unitary transform (T-DCT) on AWGN and Rayleigh fading channels is proposed. The T-transform is developed through the sparse matrices factorization using tensor product scheme. Several signaling formats such as quadrature phase shift keying and 16-ary quadrature amplitude modulation are considered. Theoretical analysis of the T-transform for DCT based OFDM is presented in this work. Analysis and simulation results demonstrated that the proposed OFDM system achieves lower PAPR and the better BER over AWGN and Rayleigh fading channels. Compared to T-DFT of OFDM, T-DCT of OFDM is found to have lower PAPR and better BER therefore, T-DCT OFDM system outperforms the T-DFT OFDM on AWGN and Rayleigh fading environments. Simulation results are used to examine and compare the PAPR and the BER performance of T-DCT OFDM system and T-DFT OFDM system. Numerical results show that the T-DCT OFDM system outperforms the T-DFT OFDM system on AWGN and Rayleigh channel models.

BIT ERROR RATE ANALYSIS OF WIMAX PHYSICAL LAYER UNDER SUI AND AWGN CHANNEL MODEL WITH VARYING CYCLIC PREFIX, MODULATION TECHNIQUES AND CODING SCHEMES

Requirement of portable, mobile and high speed connectivity for internet access is increasing day by day. WiMAX will be playing an important role in the Broadband Wireless Technology (BWT) sector, since it is more cost-effective and easy to install technology. It is a fixed Broadband Wireless Access (BWA) system based on the IEEE 802.16 standards and will be used to provide “last mile” access to the broadband and Internet access services. The WiMAX technology is based on the IEEE 802.16-2004 Air Interface Standard and is rapidly proving itself as a technology that will play a significant role in fixed broadband wireless metropolitan area networks. It is based on the concept of orthogonal frequency division multiple access technique in wireless communication. This paper investigates the performance of WiMAX network under AWGN and SUI Channel Model by varying physical layer parameter such as higher M-ary modulation, coding scheme and cyclic prefix.

4S 해상 통신을 위한 채널 추정 알고리즘 비교 연구

In this paper, we compare the existing channel estimation technique for 4S (Ship to Ship, Ship to Shore) maritime communications under AWGN channel model, Rician fading channel model, and Rayleigh fading channel model respectively. In general, the received signal is corrupted by multipath and ISI (Inter Symbol Interference). The estimation of a time-varying multipath fading channel is a difficult task for the receiver. Its performance can be improved if an appropriate channel estimation filter is used. The simulation is performed in MATLAB. In this simulation, we use the popular estimation algorithms, LMS (Least Mean Square) and RLS (Recursive Least-Squares) are compared with respect to AWGN, Rician and Rayleigh channels.

Linear-constant log-map, a fast accurate algorithm for map decoding

This paper proposes a new approximation to be used for the correction function in the turbo decoding algorithm, called Linear-Constant-log Map. Max-log Map, Linear-log Map and Constant-log Map are the well known simplified versions of Jacobi-log Map (Maximum a Posteriori) algorithm already in use but they cannot meet a proper performance in term of output BER and clock consumption of the CPU decoding encoded bits. The proposed algorithm first breaks the correction function domain of the Jacobi logarithm to three subsections by determining the border points between these sections and then uses a linear function and two constant values as an approximation of this function. Using an AWGN channel model, simulation results show that the new algorithm is almost more than six times faster than Jacobi-log Map algorithm with a Bit Error Rate (BER) very close to it.

A Neural Approach for Compensation of Effects of PAPR Causing BER Degradations in Hiperlan2

Emergent telecommunication systems use spectral efficient multilevel modulation formats together with multicarrier schemes such as Orthogonal Frequency division multiplexing (OFDM). OFDM transmission is an efficient way to deal with multipath. However one of its major drawbacks is its sensitivity to nonlinear distortions due to its greatly variable envelope and high peak to average power ratio (PAPR). Nonlinear distortions are mainly introduced by high power amplifiers (HPA), cause in band distortions. Misalignments in IQ modulators and demodulators causes imbalance, which results in loss of orthogonality and create intercarrier interference and spectral regrowth in an OFDM system. Nonlinear distortions also cause intermodulation effect. This degrades Bit error rate (BER) performance of the system. This paper introduces the self organization map(SOM) and parameterless self organization map(PLSOM) based and Hiperlan/2 receiver structure used for the compensation of nonlinear distortions. Simulation results presented in this paper clearly indicate the improved performance of the proposed system. Simulations are run for AWGN channel model and for two HPA models namely Travelling wave tube amplifier (TWTA) and Solid state power amplifier (SSPA), with and without SOM and PLSOM neural network blocks.

Performance Analysis of MC-CDMA Sytems Using Chaotic and Conventional Spreading Sequences

Performance evaluation and comparison of multi-carrier code division multiple access (MC -CDMA) system model for usually used spreading sequences (Golay, Zadof-Chu, Gold) with chaotic sequences (generated by improved logistic map, by chaotic map with different slopes and by tent function) at the presence of Saleh and Rapp model of high power amplifier (HPA) is investigated. Rayleigh channel model and AWGN channel model is used in this simulation. Nonlinear amplification of HPA introduces degradation of bit error performance and destroys the orthogonality among subcarriers. In order to avoid performance degradation without requiring extremely large backoffs in the transmitter amplifier, it becomes convenient to use nonlinear multi-user detection techniques at the receiver side for all spreading sequences. To illustrate this fact, microstatistic multi-user receiver (MSF-MUD) and conventional minimum mean square error receiver (MMSE-MUD) are considered and mutually compared. The results of analyses are based on computer simulations. The best performance for Rayleigh channel model we can obtain when we used the Golay or Chaotic sequences in combination with MSF-MUD or MMSE-MUD, with using 8 –PSK modulation type.

Interference Cancellation Schemes in UWB Systems Used in Wireless Personal Area Network based on Wavelet based Pulse Spectral shaping and Transmitted Reference UWB using AWGN Channel Model

For high data rate ultra wideband communication system, performance study of mutual interference such as suppression of interference signal by performing pulse shaping from UWB to other narrowband system using wavelet technique and reduction of interference from other narrowband system to UWB system in conjunction with Transmitted-Reference (TR-UWB) signaling scheme with adaptive receivers is attempted in this paper. The TRUWB signal using wavelet is based on multi-resolution technique to avoid its interference to other wireless systems. Ultra Wideband (UWB) wireless systems supposed to coexist with other spectrally overlapping wireless systems such as narrowband interference (NBI), multiple NBI and wideband interference allocated from 3.1GHz to 10.6GHz. So suppression of UWB from other system can be performed by using Eigen value decomposition using wavelet technique. Mutual interference degrades the performance of the TRUWB system using auto-correlation receivers (AcR). In this paper adaptive receiver (using notch filter) is used for detection and suppression of mutual interference (narrowband and wideband signal) which do not require modification of the narrowband system. The bit error rate performances are investigated using MATLAB simulation under AWGN channel model. At 10-2 BER floor, TRUWB using adaptive receiver with NBI simulations under AWGN provides a more than of 6 dB SNR improvement than that of TR using AcR receiver with NBI. The performance degrades when coexistence of multiple NBI and wideband interference wireless system with UWB system is applied using the same receiver. KeywordsTR-UWB, AWGN Channel Model, NBI, multiple NBI , wideband interference ,Bit Error Rate .

OFDM 시스템에서 효율적인 샘플링 주파수 옵셋 추정 기법에 관한 연구

OFDM 시스템에서 송수신단의 샘플링 주파수가 정확하지 않을 경우 샘플링 주파수 옵셋으로 인한 ICI(Inter-Carrier Interference) 현상이 발생하여 수신 성능의 열화를 초래한다. 일반적으로 샘플링 주파수 옵셋은 주파수 영역에서 2개의 인접한 OFDM 심볼의 동일한 파일럿 위치에서의 부반송파간 상관을 통해 추정하게 되는데, 본 논문에서는 인접한 심볼뿐만 아니라 더 많은 연속된 심볼들 간의 다양한 조합을 통한 상관을 이용하여 샘플링 주파수 옵셋을 추정하는 기법을 제안한다. 제안된 방법을 DVB-T(2K 모드) 시스템에 적용하여 모의실험을 진행하고, 이를 통해 AWGN 채널 환경에서 심볼들 사이의 잡음의 영향을 줄임으로써 샘플링 주파수 옵셋 추정 성능을 향상시킬 수 있음을 확인한다. In an OFDM system, the sampling frequency offset between the transmitter and receiver is known to cause the inter-channel interference (ICI), resulting in performance degradation. Sampling frequency offset can be generally estimated by correlation of the pilot signal within contiguous OFDM symbol. In this paper, we propose sampling frequency offset estimation schemes using various mixture of consecutive symbols. We conduct a simulation in DVB-T(2K mode) system, which shows that the proposed schemes can improve the performance of sampling frequency offset estimation by decreasing noise effect within consecutive symbols in AWGN channel model.

高度ＢＳデジタル放送用ＬＤＰＣ符号の設計

We have been studying an advanced satellite broadcasting system which is aimed at improving the Integrated Services Digital Broadcasting for Satellite (ISDB-S) system. By making use of LDPC codes and the reduced roll-off factor, this advanced system can increase its transmission channel capacity to 30% that of the ISDB-S one. Furthermore, by applying multi-level amplitude phase shift keying (M-APSK) modulation schemes, we can increase the transmission channel capacity. We report on LDPC codes that are designed for the transmission format of the advanced satellite broadcasting system. The computer simulation results of B/Q/8PSK performances under the AWGN channel model are also reported. We also discuss and report the optimization result gained from a computer simulation of the radius ratio of LDPC-coded 16APSK and 32APSK modulation, which is proposed in this advanced system, with respect to Bit Error Rate (BER) under the AWGN channel model.

Computation of the Normalized Detection Threshold for the FFT Filter Bank-Based Summation CFAR Detector

The FFT filter bank-based summation CFAR detector is widely used for the detection of narrowband signals embedded in wideband noise. The simulation and implementation of this detector involves some problems concerning the reliable computation of the normalized detection threshold for a given probability of false alarm. This paper presents a comprehensive theoretical treatment of major aspects of the numerical computation of the normalized detection threshold for an AWGN channel model. Equations are derived for the probability of false alarm, Pfa, for both non-overlapped and overlapped input data and then used to compute theoretical upper and lower bounds for the detection threshold T. A very useful transformation is introduced that guarantees the global quadratic convergence of the Newton-Ralphson algorithm in the computation of T for overlapped data with an overlap ratio not exceeding 50%. It is shown that if the product of the number of FFT bins assigned to a channel for signal power estimation and the number of input data blocks is relatively small, e.g., less than 60, the theoretical normalized detection threshold can be accurately computed without numerical problems. To handle other cases, good approximations are derived.