BER Curves Research Articles

Comparisons of PSK, APSK, and QAM over AWGN and fading channels

In addition to the thermal noise, communication systems can normally experience various fading because of objects reflecting the signal. PSK, APSK, and QAM modulation schemes are widely used in communication systems. It is thus essential to know how well these schemes can perform in different fading channels. This research explores the BER performance of these modulation schemes in common and typical channel models including AWGN, Rayleigh fading, Rician fading, and Nakagami fading channels by simulations in MATLAB. The BER curves over a range of SNR and symbol constellation diagrams are obtained. It is found that Rayleigh and Nakagami fading distort signals most and impacts of Rician fading in LoS case and AWGN can be mitigated significantly by increasing the SNR. Furthermore, the QAM has better BER performance in fading channels while PSK and APSK perform better in AWGN channels when the number of bits of one symbol is relatively small. Selections of modulation schemes should depend on the specific circumstances and the optimization of them is required when large numbers of bits are transmitted by one symbol.

Detection of Data over wireless mobile channels based on Maximum Likelihood Technique

Next generation wireless systems are characterized by very high transmission bit rates which gives rise to severe Intersymbol interference (ISI) and this makes the detection process very challenging. Hence, assessment of performance of near-optimal detectors like Near Maximum Likelihood Detectors (NMLD) over such channels assumes great importance. This paper deals with the detection of data in the presence of Noise and ISI with NMLD. Performance improvement of NMLD, as compared to nonlinear equalization, has been assessed in terms of BER versus SNR curves obtained through computer simulation. A number of different cases of mobile radio channels have been simulated in this work. In current world the lot of congestion leads severe fading and interference in the channel which may give the pause in data streaming and call drop in voice calling. These channels have different number of reflected paths with different power distribution in the respective paths. The aim of this paper is to take a ‘worst case’ model of a mobile radio channel in terms of rapidity of fading and ISI, and then to investigate the performance of detectors in the receivers.

On the performance of companding techniques for DMT optical links

In this paper the performance of Discrete Multi-Tone (DMT) optical links using nonlinear companding schemes for peak-to-average power ratio (PAPR) reduction is investigated. First, it is developed an analytical expression to evaluate the total distortion at the demodulation stage introduced by the expansion process, and also to estimate the BER vs. SNR performance curves for companded DMT systems. The analytical expression and procedure for BER estimation is tested with three compressing functions: μ-Law, Erf and Trapezoidal. The obtained results show a very good agreement between simulations and predictions, validating this simple, quick and accurate BER estimation tool for the considered system. Next, the effects produced by a nonlinear laser diode (modeled as a lower hard limiter) that is directly modulated, are investigated in terms of its input back-off (IBO). A trade-off between the distance that can be reached in an optical fiber link and the allowed BER degradation is numerically demonstrated. These results are compared against a nonlinear amplifier model (soft limiter), which results in a slight improvement in performance. Finally, it is shown that even though companding schemes degrade the BER for nearly linear operation, they can improve the BER performance of a DMT link if a moderate back-off value is allowed (particularly for an IBO=7 dB when the SNR>20 dB for a system with an Erf companding).

Systematic Performance Comparison of (Duobinary)-PAM-2,4 Signaling under Light and Strong Opto-Electronic Bandwidth Conditions

We present a systematic comparison of PAM-2 (NRZ), Duobinary-PAM-2, PAM-4, and Duobinary-PAM-4 (duo-quaternary) signaling in the context of short-reach photonic communications systems using a Mach–Zehnder modulator as transmitter. The effect on system performance with a relaxed and constrained system’s opto-electronic bandwidth is analyzed for bit rates ranging from 20 to 116 Gb/s. In contrast to previous analyses, our approach employs the same experimental and simulation conditions for all modulation formats. Consequently, we were able to confidently determine the performance limits of each format for particular values of bit rate, system bandwidth, transmitter chirp, and fiber dispersion. We demonstrate that Duobinary-PAM-4 is a good signaling choice only for bandwidth-limited systems operating at relatively high speed. Otherwise, PAM-4 represents a more sensible choice. Moreover, our analysis put forward the existence of transition points: specific bit rate values where the BER versus bit rate curves for two different formats cross each other. They indicate the bit rate values where, for specific system conditions, switching from one modulation to another guarantees optimum performance. Their existence naturally led to the proposal of a format-selective transceiver, a component that, according to network conditions, operates with the most adequate modulation format. Since all analyzed modulations share similar implementation details, signaling switching is achieved by simply changing the sampling point and threshold count at the receiver, bringing flexibility to IM/DD-based optical networks.

Proof-of-Concept of the Time and Spectral Optical Aggregation Network

In this article, we present the proof of concept (PoC) of the time and spectral optical aggregation (TISA) approach that allows a better filling of the time and spectral resources of an optical transport network. Some innovative solutions have been implemented, such as a new and fast tunable laser that permits to color the bursts sent in the TISA network, as well as their transmission with both DP-QPSK and DP-16QAM coherent multi-band (MB) OFDM formats. BER versus OSNR measurements have been achieved showing less than 1-dB penalty in back-to-back or after transmission. The tolerance of bursts against frequency mismatch occurring between the transceiver and the optical filter that extracts a sub-band inside the MB-OFDM signal has also been evaluated, and ∼1.5 GHz tolerance has been measured for bursts of ∼6.7 GHz bandwidth. Furthermore, in order to mitigate the transients in the coherent receiver that faces alternatively the presence or absence of signal, a novel channel estimator based on a sliding window has been introduced. Its efficiency and performance has been experimentally validated, and its ability to suppress the error threshold of the BER versus OSNR curves has been demonstrated. By the experimental proof of concept delivered here, the ability of the TISA network to perform with a good level of performance the transparent routing and sub-wavelength aggregation/disaggregation in the time and spectral domains simultaneously has been established. Beyond the important and crucial aspect of the optimal filling of the optical resources, our PoC demonstrate the ability of the TISA approach to push the flexibility of an optical transport network at its limit while allowing a cost and power consumption limitation obtained by the removal of costly and power-hungry optical-electrical-optical regenerators.

The Effect of Feedback Delay on the Performance of Closed-Loop Rotate Modulations on OFDM/OFDMA Systems

In this paper, in order to improve the performance of the OFDM/OFDMA system, novel closed-loop rotate modulation is proposed by utilizing feedback channel state information in the complex values. The basic idea of the proposed rotate modulation is the channel equalizer process, which is applied at the transmitter side; therefore, it does not need to insert guard time to anticipate the problem of channel delay spread. With the purpose of distortionless-transmission, in this paper, the rotate modulation equation has been derivated. Based on the simulation results on this proposed system, when the feedback delay has been zero, the resulting system performance has been similar to the one on the Additive White Gaussian Noise channel. In this ideal condition, the received signal has been similar to the transmitted signal although in real condition the process of transmitting the feedback signal will always result in a delay. Simulation results at low-level modulation such as Binary Phase Shift Keying and Quarternary Phase Shift Keying; the system bit error ratio performance has not shown degradation with the feedback delay. However, for higher level modulation such as 16-Quadrature Amplitude Modulation and 64-Quadrature Amplitude Modulation, the feedback delay has caused degradation on the BER curve.

Performance improvement of space diversity technique using space time block coding for time varying channels in wireless environment

Performance improvement of space diversity technique using space time block coding for time varying channels in wireless environment

MMSE based beamformer in massive MIMO-IDMA downlink systems

Abstract Now-a-days Massive MIMO (mMIMO) become an attractive technology due to its spectral and energy efficiency by the means of simple signal processing. However, in overloaded scenario, wherein the number of users equipments (UEs) are larger than number of antennas, the spectral effciency (SE) suffers and hence error rate performance, it has been shown recently that use of code domain NOMA in mMIMO can improve the SE performance. Further, interleave division multiple access (IDMA) has been drawn much attention as a suitable code domain non-orthogonal multiple access (NOMA) for future communication standards. This paper proposes the work in two folds, first a massive multiple input and multiple output (MIMO) and IDMA communication system is jointly proposed in which antennas on the base station serves users simultaneously in the same frequency band. Both and are large in numbers. Secondly, the minimum mean square error (MMSE) based beamformer is suggested to combat the propagation loss and effect of multiple access interference (MAI), for massive MIMO-IDMA system under downlink communication constraints. With the help of simulation results, the performance of the proposed system with MMSE beamforming have been investigated in terms of BER vs SNR curve plot.

Design and Analysis of Single-Channel High-Speed RoF System Using Different Coding Techniques

In this paper, we have discussed the single-channel radio over fiber system using single-mode Optical Fiber. In this article, we compared RZ, NRZ, and Gaussian pulse techniques. For performance analysis, we have used a 10 Gbps data rate and transmitted the ON-OFF signal using 60 GHz (V band) millimeter-wave over various optical lengths between 25 Km and 80 km. We successfully demonstrated that Gaussian pulse and NRZ provide better performance as compared to RZ for long-distance up to 80 km. RZ performs better for short-distance communication up to 50 km of a fiber link. The system performance is evaluated using the BER curve, Q factor, eye diagram, and output of the spectrum analyzer.

Performance evaluation of OFDM systems over α – κ – μ fading

In this Letter, the authors derive the moment generating function-based BER expressions for binary phase shift keying and M-QAM signal for OFDM systems over –– fading. This fading model is known as the generalised fading model because it can accurately characterise all the well known small-scale fading models given in the literature. In order to validate the derived BER expressions, analytical and simulated BER curves for a variety of modulation formats at different values of fading parameters are also shown in the letter.

Effects of atmospheric weather and turbulence in MSK based FSO communication system for last mile users

In this paper, a minimum shift keying (MSK) based free space optical (FSO) communication system for the terrestrial user is modeled. In our setup 10 Gbps downlink MSK modulated signal is transmitted first over 100 km dispersion shifted fiber and then the area where deployment of fiber is not possible due to some constraints, FSO link is used to transmit the data to the last mile users. FSO link suffers from various weather conditions and atmospheric turbulence i.e. scintillation effect. Hence, both the cases are considered to transmit the data through FSO link to the end users and Gamma–Gamma fading model is used to study the scintillation effect. FSO link range is optimized to analyze the behaviour of the proposed system for six different weather conditions over weak, moderate and strong turbulence using BER curves and eye diagrams. Also, from the base station uplink data is modulated by MSK and is transmitted back to central station via same fiber and detected successfully.

Performance evaluation of VLC system using new modulation approach

We propose a modified OFDM modulation based on multiband scheme for visible light communications (VLC) system. The method called catenated-OFDM VLC system can efficiently boost the propagation distance and combat multipath induced the inter symbol interference and inter carrier interference. Design parameters such as number of optical bands, input power, distance and data rate are varied to see their effect on the system performances. Simulation analysis is done using Optisys software Ver. 11.0. The results show that the proposed system offers a good performance at longer transmission distance of 12 m for input power of 2 dBm in case of Band=3 with 10 Gbps data rate. BER curves also indicates that the proposed system can be operated at very high data rate of 15 Gbps. This exhibits the ability of the proposed system to be one of the candidate for future optical wireless communication system.

BER and Capacity Improvement for Multiuser MIMO System by MRT Precoding Technique

In recent years several of endeavors have been conducted in various papers to improve capacity and bit error rate performance of multiuser MIMO system. Every effort tried to increase gain of the individual stream between base station and users’ antennas while reducing the interference among multiple users and interference between streams of single user itself. All these papers adopted precoding techniques for beam forming of individual stream. Various papers have compared precoding techniques such as DPC, BD-ZF, BD-MMSE, BD-QR-MRL, and BD-QR-LRL. Block diagonalization technique is capable to reduce multiuser interference, but not able to combat interference between antennas of single user itself. BD combines with other techniques to overcome this problem. This paper also proposes a precoding technique called modified maximum ratio transmission, which is able to deal with the problem without much complexity. Simulation is done to compare all precoding technique with MRT. The paper tests the precoding techniques on the parameters of BER and capacity, to achieve optimum receiver performance. BER curve and capacity curve are plotted to conclude the paper.

In brief

PAGE 274 Internet use on aircraft is prohibited with current RF wireless communication technologies but a team of researchers in Italy is proposing to use visible light communications as an alternative to enable access. Reading lights are investigated as signal source emitters to user devices and the minimum capacities needed to practically implement such a system are reported. PAGE 244 A pair of researchers in the UK have proposed a novel combination of wireless and conventional metallic interconnects to improve the performance of an on-chip clock distribution. Their results show a dramatic reduction in total delay compared with other advanced models and demonstrate that some clock uncertainties become predictable. Perspective view of Airbus A320 cabin model. PAGE 278 An optic fiber one-piece flexible sensing probe for liquid level sensing in cryogenic propellant tanks has been presented by researchers in China. The probe is ultra-lightweight and provides advantages over currently existing models in gauging accuracy, reliability, simplicity and maintenance with results from the measurement of liquid nitrogen levels. Proposed hybrid wireless architecture. PAGE 282 Researchers from China have successfully demonstrated the high performance of a normally-off recess-gated AlGaN/GaN metal-insulator semiconductor field-effect transistor (MISFET) with an operating temperature of 200°C. The device was fabricated using a self-terminating gate recess etching technique and states the highest reported value for an off-state gate breakdown voltage for a normally-off device operating at this temperature. Schematic experimental setup for measurement. PAGE 288 A new symbol detection scheme for uplink wide-banded cyclic prefixed filter bank multiple access (CP-FBMA) systems has been proposed by researchers in China. The new scheme has the benefits of lower complexity and higher spectral efficiency due to a feature that eliminates the analysis filter bank processing that is commonly employed in existing schemes. Cross-section of the AlGaN/GaN MISFET. BER curves of different systems.

Convergence analysis of the unpunctured turbo trellis-coded modulation (UTTCM)

In this paper, the performance of the Unpunctured Turbo Trellis-Coded Modulation (UTTCM) over Additive White Gaussian Noise (AWGN) channel is analyzed using the non-binary extrinsic information transfer (EXIT) chart. The exchange of the extrinsic information between the decoder components is tracked, allowing the generation of an EXIT chart, which is a powerful tool for analyzing the convergence behavior of iterative decoding and prediction of convergence position. The Simulation results are compared with the turbo cliff positions on the BER curves.

Spatially-Coupled Codes for Channels with SNR Variation

Spatially-Coupled Codes for Channels with SNR Variation

Photonic generation of frequency-quadrupling millimeter-wave vector signal based on balanced detection without precoding

Photonic frequency-quadrupling millimeter-wave (mm-wave) vector signal generation is proposed by balanced detection without precoding. A dual-polarization quadrature phase shift keying (DP-QPSK) modulator is the main component of the scheme. In the DP-QPSK modulator, An optical carrier and ± 4st-order optical sidebands can be obtained in one QPSK modulator, while the other QPSK modulator driven by 16QAM baseband electrical I/Q data. After balanced detection, a 16QAM vector signal can be obtained by frequency-quadrupling. The proposed scheme can reduce the complexity of transmitter digital signal processing. By adjusting the sub modulators of the DP-QPSK modulator, a 4 Gbaud baseband 16QAM vector signal can be generated at 40 GHz by frequency-quadrupling. In addition, after 20 km single-mode fiber (SMF) transmission, the constellation, eye diagrams and the BER curves of the frequency-quadrupling mm-wave vector signal perform well.

Performance investigation of 110-Gbps optical MSK system using a Quad Mach-Zehnder IQ modulator

In this paper, numerical simulation is conducted to investigate the generation, transmission and detection of a 110 Gbps optical Minimum Shift Keying (MSK) signal. The transmitter has been designed using a Quad Mach-Zehnder IQ Modulator. At the transmitter, a 110 Gbps optical MSK signal with constant envelope and a continuous phase is generated by combining signals of I-arm and $$90^\circ$$ phase shifted of Q-arm. Error-free transmission of 110 Gbps optical MSK signal is achieved after traversing a distance of 240 km, also a comparison is made with respect to Differential Phase Shift Keying (DPSK) to show its effectiveness. At the receiver side, the original signal is recovered through a balanced detection method, with a power penalty of around 3.34 dB. Also, BER curves of different bit rates for MSK are studied ranging from 40 to 120 Gbps and found that maximum 110 Gbps can be achieved error-free. The optical spectrum of both MSK and DPSK signals are observed and found that MSK is having narrower main lobes with smaller side lobes compared with that of DPSK, which in turn results in an increase in spectral efficiency and reduction in intersymbol interference.

Implementation of Galois Field for Application in Wireless Communication Channels

This paper discusses the implementation of Galois Field based codes for application in wireless communication channel. It discusses the use of Galois Fields outlining the basic performance of a digital communication system in terms of BER curves. The work further discusses the performance of these codes in Gaussian and Rayleigh Fading Channels.

Optimal signal mapping scheme for MIMO-BICM-ID transmission over the different fading channel using whale algorithm

The designing of signal mapping scheme for bit-interleaved coded modulation (BICM) systems has been received significant interest among the researchers recently due to the growing interest of using Multiple Input Multiple Output (MIMO) system. The bit-interleaved coded modulation systems are need of effective design in constellation mapping with iterative decoding that outperformed the existing BICM coding in time varying characteristics of the channel. In this paper, the design of optimal constellation mapping of the BICM system with iterative decoding for MIMO channel is proposed. Based on minimizing cost, a design criterion is proposed to find the optimal constellation mapping for an MIMO-BICM-ID system. Here, a cost function is designed to search an optimal mapping scheme using the well-known optimization algorithm called, whale algorithm. Using this method, we find some optimal constellation mapping for 2-dimensional and 3-dimensional cases. The designed technique is evaluated with the help of BER curve for different fading channels.