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Современные системы радиопередачи цифровых сигналов используют достаточно широкополосные трак-ты передачи, для которых характерно наличие частотно-селективных замираний, ведущих к межсимвольной интерференции (МСИ) принимаемых символов. Это приводит к заметному снижению помехоустойчивости связи вплоть до полного её срыва. Для борьбы с этим предлагается применять метод коррекции МСИ. Для этого перед каждым информационным символом излучается специально сформированный корректирующий символ. Его параметры регулируются таким образом, чтобы сумма с предыдущими «меша-ющими» символами была минимальной. Регулировка может осуществляться либо непосредственно амплитудно-фазовых параметров корректирующих символов («физическая» коррекция), либо с использованием особенностей метода QAM-модуляции. При QAM-модуляции для передачи информационных сим-волов уже производится амплитудная регулировка несущей с использованием QAM-модулятора передатчика. Подавая соответствующие логические коды, можно достаточно точно сформировать требующиеся корректирующие символы («логическая» коррекция). Исследована сравнительная эффективность обоих методов. Приведён пример реализации описанного метода «логической» коррекции., Higher data traffic via any transmission channels currently results in using signals increasingly broader in spec-trum and increasingly broader spectral bandwidth of transmission path. That said multipath propagation of radio waves is observed in many types of channels. Various beams come to the receiver along different paths and have varying levels and varying time delays. It results in signal power dissipation and adjacent symbols’ overlapping. Symbols interfere with each other and this causes their distortion and data transmission downgrade. To combat this phenomenon it is proposed to use the redundancy of transmitted symbols’ quantity compared to the quantity of initial information symbols. A special correction symbol is transmitted before each information symbol. It is readjusted so that to remove summation of all prior symbols or significantly reduce its level. The method is used in two-way transmission systems. Test sessions are conducted occasionally whereby the parameters of trans-mission channel and obstructive symbols that are added to the basic symbol are measured. The measured parameters are transmitted back to the sending station. Quite a sophisticated equipment is applied in the transmit-ter for tuning. This is how “physical” method of correction is implemented. Amplitude and phase of each correction symbol must be controlled. However, QAM (quadrature amplitude modulation) method enables to consider-ably simplify this procedure using “logical” correction method. Amplitude-phase control of transmitted signals is already performed in this method when transmitting information symbols. Therefore, it is quite enough to input such a binary code to the modulator instead of amplitude-phase control of the correction symbol, so that a symbol is formed at the modulator output and it is as similar as possible to the required type of correction symbol. The method loses to the "physical" correction method in terms of noise immunity, but discrepancies are slight in case of QAM-64, QAM-256 modulation. Implementation scheme for the proposed method is given. Computer-aided research results of the method efficiency are described

The use of wireless implanted medical devices (IMDs) is growing because they facilitate monitoring of patients at home and during normal activities, reduce the discomfort of patients, and reduce the likelihood of infection associated with trailing wires. Currently, radio frequency (RF) electromagnetic waves are the most commonly used method for communicating wirelessly with IMDs. However, due to the restrictions on the available bandwidth and the employable power, data rates of RF-based IMDs are limited to 267 kb/s. Considering standard definition video streaming requires data rates of 1.2 Mb/s and high definition requires 3 Mb/s, it is not possible to use the RF electromagnetic communications for high data rate communication applications such as video streaming. In this work, an alternative method that utilizes ultrasonic waves to relay information at high data rates is introduced. An advanced quadrature amplitude modulation (QAM) modem with phase-compensating, sparse decision feedback equalizer (DFE) is tailored to realize the full potential of the ultrasonic channel through biological tissues. The proposed system is tested in a variety of scenarios, including both simulations with finite impulse response (FIR) channel models, and real physical transmission experiments with ex vivo beef liver and pork chop samples as well as in situ rabbit abdomen. Consequently, the simulations demonstrated that video-capable data rates can be achieved with millimeter-sized transducers. Real physical experiments confirmed data rates of 6.7, 4.4, 4, and 3.2 Mb/s through water, ex vivo beef liver, ex vivo pork chop, and in situ rabbit abdomen, respectively.

This paper presents an analysis work for suitable signal modulation schemes on Narrowband 3 kHz HF channels. The most efficient power for each constellation size in QAM and PSK schemes are calculat...

In this paper, a scheme with single-ended PD and single DDMZM is applied for complex QAM signal transmission. The scheme can provide an efficient low-cost and low-complexity solution for long reach PON. Due to its minimum phase property of the optical SSB signal, Kramers-Kronig scheme can be used to reconstruct the complex QAM signal from the received intensity signal. The efficiency of this scheme is validated by both numerical simulations and experiments with QPSK, 16-QAM and SSB-modulated PAM-4 signals. We have experimentally demonstrated single-channel 42.5 Gbps over 75-km using standard commercially available components with the combination of single DDMZM and direct detection receiver with KK scheme using SSB modulated 16-QAM and PAM-4 signal.

Although, most researchers focus on some of the key components of good digital wireless communications which are the Bit Error Rate (BER) versus Signal to Noise Ratio (SNR) of modulation schemes. Energy consumption optimization is necessary for enhancing the performance of a wireless communication system as it offers numerous advantages to the system and the users. Therefore, this research focuses on analyzing the efficiency in the performance of the various QAM Modulation Schemes (4QAM, 16QAM, 32QAM & 64QAM) as they travel over noise/fading channels with the quest to obtain an energy-efficient scheme which will enhance system performance in terms of system runtime and quality of service. The efficiency of any given process, operation, or device is rated per the energy it consumes in carrying out an activity per unit output. Hence, the objective of this research work is to study and analyze comparatively the efficiency of these modulation schemes and to conclude with the most efficient scheme over the various channels. The evaluation of the Bit Error Rate (BER) versus energy per bit to noise spectral density (EbNo) for each communication scenario was carried out in MATLAB.

We present record unrepeatered experiments with 61 real-time 32-QAM channels at 500 Gb/s over 276.4 km, or with hybrid 16/32 QAM modulation over 292.5 km, applying a high-power booster and third-order Raman amplification.

The paper proposes a method for scheduling frequency and power resources between users to ensure equal throughput in the downlink channel when non-orthogonal multiplexing of users in power domain of orthogonal subcarriers (PD-NOMA/OFDMA). This method allows the multiplexing of several user signals with different power in a single frequency-time segment. The existing approaches to resource scheduling are based on the use of ideal signal-code sequences with perfect noise immunity characteristics. This does not allow an accurate estimate of the PD-NOMA system throughput in real operating conditions. To solve this problem, it is necessary to design a new method of power scheduling that takes into account the type and characteristics of real modulation and coding scheme (MCS). The novelty of the paper is to take into account currently used MCS’s based on QAM modulation and LDPC coding in power scheduling. A designed scheduling method is using strategy of achieve equal throughput of users and maximize system throughput. To estimate the PD-NOMA system throughput using the proposed methods, a simulation model of the PD-NOMA/OFDMA system’s downlink channel has been developed. The average throughput gain of the PD-NOMA/OFDMA system relative to OFDMA was 19% over 100 simulation iterations #CSOC1120.

Wireless communications is one of the most active areas of technology development of our time. This development is being driven primarily by the transformation of what has been largely a medium for supporting voice telephony into a medium for supporting other services, such as the transmission of video, images, text, and data. In this paper QAM modulation techniques used for calculation of SNR with MIMO system using fading channel. This work presents, a simulation toll MATLAB R2013a to study the performance analysis of Bit Error rate BER V S Signal to Noise ratio SNR . Prerna Amlavad | Mukesh Ptidar "Performance Analysis of Different QAM Techniques Using Rician Fading Channel" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-1 , December 2018, URL: https://www.ijtsrd.com/papers/ijtsrd20214.pdf

The 60 GHz technology engage between 57 GHz to 66 GHz occupying an unlicensed band consisting of four channels with 2 GHz bandwidth each. The wavelength of such technology approximates 5 mm enabling milli-meter wave communication. It benefits transmission security for crucial data. Indoor networking equipment with large bandwidth and high-capacity streams lag free High-Definition video from tablet to television. This paper intends to present the simulation studies on 60 GHz mm-wave band technology employing QAM modulation for wireless applications. The experimental results were obtained by simulating the designed architecture in Agilent ADS software tool and further presented to deduce the insight of future Wi-Fi for wireless applications.

Orthogonal frequency division multiplexing (OFDM) is a transmission system that uses multiple orthogonal carriers that are sent out at the same time. OFDM is a technique for mobile and wireless communication that has high-efficient frequency utilization, high data-rate transmission, simple and efficient implementation using the fast Fourier transform (FFT) and the inverse fast Fourier transform (IFFT), and reduces inter symbol interference (ISI) by inserting cyclic prefix (CP). One of the most important approaches in an OFDM system is channel estimation. In this paper, the orthogonal frequency division multiplexing system with the Rayleigh channel module is analyzed for different areas. The proposed approach used large numbers of subcarriers to transmit the signals over 64-QAM modulation with pilot add channel estimation. The accuracy of the OFDM system is shown in the measuring of the relationships of peak power to the noise ratio and bit error rate.

In this paper, we have proposed MIMO-IBFD system that can transmit and receive multiple data stream at the same time in the single band, and analyze the system. We have confirmed that MIMO-IBFD system requires multiple RF cancellation and multiple Digital cancellation techniques. In simulation, we have analyzed characteristic of received signal on MIMO-IBFD system, and evaluate system performance of conventional 2x2 MIMO system and MIMO-IBFD system. As simulation results, we have confirmed that MIMO-IBFD system can transmit and receive multiple data stream at the same time in the single band by using multiple RF and digital cancellation techniques. Additionally, we have confirmed that BER performance of 2x2 MIMO-IBFD system with low-level QAM modulation is similar to performance of 2x2 MIMO system, and BER performance of 2x2 MIMO-IBFD system with high-level QAM modulation is degraded in comparison with 2x2 MIMO system with high-level QAM modulation. We can confirm that MIMO-IBFD system requires high level self-interference cancellation technique in order to use high level modulation. 논문 16-41-05-05 The Journal of Korean Institute of Communications and Information Sciences '16-05 Vol.41 No.05 http://dx.doi.org/10.7840/kics.2016.41.5.531 531 First Author : Department of Electronic Engineering, Chungbuk National University, acy890217@naver.com, 학생회원 ° Corresponding Author : Department of Electronic Engineering/Research Institute for Computer and Information Communication, Ch ungbuk National University, ecomm@cbu.ac.kr, 정회원 * Department of Electronic Engineering, Chungbuk National University, kkr427@hanmail.net, 학생회원 ** Department of Electronic Engineering, Chungbuk National University, bj5236@nate.com, 학생회원 논문번호:2015-11-371, Received November 23, 2015; Revised March 21, 2016; Accepted April 28, 2016 The Journal of Korean Institute of Communications and Information Sciences '16-05 Vol.41 No.05

We report on the design, fabrication, and characterization of a reflective transmitter targeting implementation in passive optical networks (PON) with frequency division multiplexed access (FDMA). It is made up of a Silicon photonic integrated circuit (Si-PIC) comprising a reflective Mach Zehnder modulator and its flip-chipped CMOS electronic integrated circuit driver, the two ICs being interconnected by means of high density and low parasitic copper micro pillars. Several transmissions, in an FDMA PON context, are successfully demonstrated using 500 MBaud QPSK and 16-QAM modulated subcarriers, achieving bit error rate below 2.10−3. For QPSK-modulated subcarriers (respectively, 16-QAM), the available access frequency bandwidth is measured to be 1–7 GHz (respectively, 2–4 GHz) with an available loss budget of 9 dB (respectively, 5 dB). Improvements of the Si-PIC are further identified to achieve compliancy with 31 dB ODN loss.

The use of optical-OFDM systems is mainly restricted by their limited dynamic range as a result of a high peak to average power ratio (PAPR) and nonlinear distortion (NLD). Radio-over-Fiber (RoF) systems are mainly deployed for light modulation and mm-wave signals transmission over fiber links. This paper evaluated the performance of RoF links with respect to their external modulation in a bid to highlight the challenges attributable to the various optical system components. The Mach-Zehnder Modulator (MZM) have been used in external modulation; it is a tested modulation scheme for quadrature amplitude modulation QAM (a vector modulation format) where signal subcarriers are generated using an OFDM scheme. Simulation results based on Optisystem 13 software exposes that the receiver performance of the optimum system for achieving has a better Bit Error Rate (BER) and three longest distance as 10, 50, 100 km for 16 QAM-OFDM-RoF system are reached by using optimum receiver launch power.

BMERA or convolutional polar codes are an extension of polar codes with a provably better error exponent than polar codes. A successive cancellation (SC) decoding algorithm for BMERA codes similar to SC polar decoders is introduced. A pseudocode description of the SC decoder that can be extended to SC list (SCL) decoding is provided. Simulation results with and without outer CRC codes under SC and SCL decoding are presented for QAM modulation over the AWGN channel to compare the performance of polar and BMERA codes. BMERA codes outperform polar codes by more than 0.5 dB under SCL decoding without outer CRC codes., submitted to ISTC 2018

A modulation format identification technique by using artificial neural network for elastic optical networks is experimentally realized in IMDD QAM-OFDM system. Experimental results demonstrate successful identification for five different QAM modulation formats.

This paper is about Simulink QAM modulation and demodulation implementation. Firstly, the basic principle of QAM modulation and demodulation system is introduced. Then, the basic operation of system modeling and simulation under simulation software Simulink is introduced. The emphasis is on modeling and simulation of 16QAM system modules, and 16QAM modulation and demodulation are realized. Finally, a 2DPSK system simulation is carried out to compare it with the 16QAM system. It is concluded that 16QAM is a relatively superior modulation and demodulation system.

We discuss a simulation program for indoor visible light communication system with hexagonal LED array shape that will allow us to focus the luminance of optical light for the room center with neglecting of the boundary since they will be occupied by furniture. It is assumed that users will not be in those areas. We are going to model OOK, PPM and QAM modulation techniques with varied semi-angle degrees, as a result we want to prove with hexagonal shape we could make and uniform luminance in the room. MATLAB and Simulink will be used for simulation.

In this paper, we propose an algorithm to extract a one-dimensional (1D) non-intuitive feature of the received signal for automatic modulation classification (AMC). This designed phase-related feature which can reflect the inherent information about modulation patterns has not been utilized before. In order to learn the intrinsic message of these extracted features and recognize their corresponding modulation types, we adopt convolutional neural network (CNN) as classifier. Furthermore, we apply CNN to some conventional features as classifier for performance comparison. Empirically, the proposed 1D feature may contains more information of the original signal compared with some conventional features. Simulation results also verify the superiority of the proposed system whose classification accuracy is beyond 99% at 0 dB.

Aeronautical communication systems will play an increasingly important role in the future. Due to increasing flight traffic, which is estimated to double by 2025, and the inadequacy of current aeronautical communication systems to support such an increase, the demand for new and state of the art communication systems is increasing. In this paper we investigate a new spectrally shaped Filter Bank Multicarrier (SS-FBMC) based communication system for air to ground communication. We study a 0.5 MHz spectrally shaped communication system as an inlay system between the 1 MHz separated distance measurement equipment (DME) channels in the L-band. The idea of using the gap in the spectrum that exists between DME channels was first proposed by EUROCONTROL in their L-DACS1 communication system. In the L-DACS1 communication system, which is based on CP-OFDM, the transmitting power is equally distributed among all subcarriers. In this paper we deviate from this convention by using FBMC and assigning different power levels to the subcarriers to mitigate DME interference. We propose a method to find the required guard subcarriers and optimize the amount of allocated power for each remaining subcarrier in order to obtain the best bit error ratio (BER) performance, without any error floor, for different QAM modulation orders and communication links. In so doing we increase the communication system's efficiency and performance. In prior work we have shown that our original FBMC system has higher spectral efficiency and better resilience to DME interference than L-DACS1, but in some cases still incurs a BER floor (as does L-DACS1). Via our spectral shaping approach we remove these BER floors.

Closed form expressions for approximate symbol error rate are obtained using moment generating function for a two branch cooperative communication system over generalised κ−μ and η−μ i.i.d. fading channels for BPSK and QAM modulation schemes. Selective decode and forward protocol is used at the relay transmitter. At the destination maximal-ratio combining is used. Monte Carlo simulations are performed to verify the analytical results.

Hybrid optical OFDM/WDM system is proposed to provide longer reach and larger capacity comparing with existing PON systems in order to meet the ever increasing bandwidth demand and data rate of next generation optical access networks. In this paper, two channels using different modulation at 10 Gb/s are used for downstream link. OFDM signals occupy different portions of the available signal spectrum for signal transmissions by using WDM. As a result, the system has good performance based on SNR with 50 km distance and QAM modulation delivers better performance compared with PSK.

Layered offset hierarchical QAM modulation scheme is proposed to enhance the high priority stream error performance by reducing the intersymbol interference from the superimposed symbols of the low priority stream. The proposed scheme shifts the symbols of the two priority layers by half the symbol duration, whereas the detector performs multi-stage maximum-likelihood detection with interference cancellation. The simulations demonstrate the performance and design options offered by the proposed scheme compared to conventional hierarchical schemes where no time offset exists between the superimposed symbols.

This paper shows the implementation of SISO communication system using QAM modulation in WARP. The performance of the proposed system is evaluated in terms of Bit-Error-Rate (BER) for different M-array level: 4, 8, and 16 in indoor and outdoor environments, both using LOS condition. In the analysis results, SISO performance with 4-QAM modulation achieves better performance compared to 8-QAM and 16-QAM for both environments. Meanwhile, SISO performance with QAM modulation in outdoor environment achieves better results compared to indoor environment for different M-array level. In indoor environment with transmitted power -26 dBm, BER achieved for 4-QAM, 8-QAM, and 16-QAM are 1.33 × 10−4, 2.078 × 10−2, and 8.76 × 10−2, respectively. While in outdoor environment with the same transmitted power, BER achieved for 4-QAM, 8-QAM, and 16-QAM are 0, 1.497 × 10−2 and 5.928 × 10−2, respectively. SISO performance using M-QAM modulation is better than using M-PSK modulation.

This paper depicts the design of passive optical network (PON) using advance modulation schemes delivering efficient solution to users. Theoretical concepts are validated by eye diagram, constellation diagram and optical signal to noise ratio (OSNR).

We propose a flexible optical SCM modem to transmit, with high spectral efficiency, mobile front-haul signals. The real time experimental results, demonstrate the multicarrier aggregation capacity of 3.6 Gbps based on four 1024-QAM D-RoF subcarriers and a 30km transmission reach.

We investigate the transmission distance of three QAM modulation formats, in the presence of inter-core crosstalk in a 7-core fiber. We show that crosstalk limits transmission distance for all formats with a greater impact on higher order modulation formats. For a crosstalk level equivalent to equal signal launch power in each core, we measure a reduced transmission distance at BER=1.5×10−2 of 17%, 23% and 36% for PDM-QPSK, PDM-16QAM and PDM-64QAM respectively.

Most of the researches in recent years have been focused on a new multicarrier system OFDM/OQAM, which is different from the traditional OFDM based on cyclic prefix (CP). Using offset QAM modulation, the new system ensures high channel utilization without CP. In the modulated and demodulated process of OFDM/OQAM, the signals must through pulse shaping using prototype filters, so an appropriate filter is particularly important. In this paper, an optimized filter based on Zak transformation is proposed, which has better time-frequency localization (TFL). The experimental simulation proved that new system can resist the effects of multipath fading and Doppler spread effectively, thus having better BER performance.

This paper presents some closed-form bit error probability expressions for coherent demodulation of both Gray coded and differentially decoded Gray coded QAM modulations in nonfading and frequency nonselective Rayleigh fading channels. These results demonstrate that as QAM constellation sizes get larger the BEP degradation due to differential encoding and decoding becomes negligible.