Adaptive minimum symbol-error rate equalization for quadrature-amplitude modulation

2003 ◽  
Vol 51 (12) ◽  
pp. 3263-3269 ◽  
Author(s):  
Chen-Chu Yeh ◽  
J.R. Barry
Keyword(s):  
Error Rate ◽  
Amplitude Modulation ◽  
Symbol Error Rate ◽  
Quadrature Amplitude Modulation

scholarly journals Moment-Based Analysis of Reg. Triangular QAM in Turbulent Atmospheric Channels with Pointing Errors incorporates Zero and Non-zero Boresight

2020 ◽  
Author(s):  
Muhammad Nabeel Shahid ◽  
Furqan Haider Qureshi ◽  
Shahzad Amin Sheikh ◽  
Qasim Umar Khan ◽  
Muhammad Zeeshan
Keyword(s):  
Atmospheric Turbulence ◽  
Error Rate ◽  
Amplitude Modulation ◽  
Communication Systems ◽  
Symbol Error Rate ◽  
Quadrature Amplitude Modulation ◽  
Optical Beam ◽  
Beam Radius ◽  
Pointing Errors ◽  
Average Symbol Error Rate

Abstract In recent years, free-space optical (FSO) technology has gained fame in communication systems due to its high data rates and license-free feature. Triangular quadrature amplitude modulation (TQAM) is an efficient modulation scheme that uses even bits per symbol, and it has a low average symbol error rate (ASER) than square quadrature amplitude modulation (SQAM). In this paper, we theoretically investigate the performance of subcarrier triangular quadrature amplitude modulation (SC-TQAM) corrupted by atmospheric turbulence in the presence of pointing errors (P.E) in FSO communications. We have considered boresight displacement, P.E effect, and atmospheric turbulence. To represent the atmospheric turbulence we consider Log-normal, Rayleigh and Rician distributions which exhibit weak, moderate and strong weather effects. The P.E is employed using Rayleigh and Rician distribution that incorporates zero and non-zero boresight displacement respectively. The moment generating functions of these models have been derived. P.E is modeled using an optical beam radius and receiver aperture radius. The combination of these parameters will help enhance the average symbol error rate (ASER). Furthermore, we have derived an analytical expression that is used to develop numerical results. The ASER performance is observed against average received irradiance, optical beam radius, P.E standard deviation and receiver aperture radius. In the end, the ASER performance is evaluated against SNR and Monte Carlo simulations are performed which validates the theoretical results.

scholarly journals An Investigation of the Impacts of Phase Noise on Symbol Error Rate in Quadrature Amplitude Modulation Systems

2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Hilary U Ezea ◽  
Kehinde Adebusuyi ◽  
Temidayo Ofusori ◽  
Rita U Ezea
Keyword(s):  
Phase Noise ◽  
Error Rate ◽  
Amplitude Modulation ◽  
Symbol Error Rate ◽  
Quadrature Amplitude Modulation ◽  
Soft Decision ◽  
Matlab Simulation ◽  
System Complexity ◽  
Soft Decision Decoding ◽  
The Impact

The existence of phase noise in virtually every digital communications system poses a serious challenge to system designers especially as system complexity increases. Communication system complexity could be attributed to the modulation techniques adopted and the circuitry employed in achieving such modulations. This work investigates the impact of phase noise on the Symbol Error Rate (SER) of the different Quadrature Amplitude Modulation (QAM) schemes.  MATLAB simulation technique is adopted for the work and the results of the simulations show that as the phase noise is increased negatively, all the QAM schemes investigated show a reduction in SER and at a point, records a zero error. The value at which the schemes record this zero symbol error rate increases as the complexity of the scheme increases. So, higher order QAM schemes accommodate more symbol errors than the lower orders. The results also show that hard decision decoding has the worst performance index, irrespective of the QAM scheme, when compared with soft decision decoding.

scholarly journals Symbol Error-Rate Analytical Expressions for a Two-User PD-NOMA System with Square QAM

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2153
Author(s):  
Yakov V. Kryukov ◽  
Dmitriy A. Pokamestov ◽  
Serafim A. Novichkov
Keyword(s):  
Error Rate ◽  
Amplitude Modulation ◽  
Multiple Access ◽  
Additive White Gaussian Noise ◽  
Time Spectrum ◽  
Symbol Error Rate ◽  
Quadrature Amplitude Modulation ◽  
Power Domain ◽  
Power Weights ◽  
Analytical Expressions

Power domain non-orthogonal multiple access (PD-NOMA) is one of the most perspective multiplexing technologies that allows improving the capacity of actual networks. Unlike orthogonal multiple access (OMA), the PD-NOMA non-orthogonally schedules multiple users in the power domain in the same orthogonal time-spectrum resource segment. Thus, a non-orthogonal multiplexed signal is a combination of several user signals (usually, modulation and coding schemes (MCS) based on quadrature amplitude modulation) with different power weights. The symbol error rate (SER) and bit error rate (BER) performances are one of the main quality characteristics of any commutation channel. The issue is that a known analytical expression for BER and SER calculation for conventional OMA cannot be applied in terms of the PD-NOMA. In the following work, we have derived the SER and BER analytical expressions for gray-coded square quadrature amplitude modulation (QAM) user channels that are transmitted in two-user PD-NOMA channel under additive white Gaussian noise (AWGN). Through the simulation, the verification of the provided expressions is presented for four multiplexing configurations with various user power weights and QAM order combinations.

scholarly journals Performance Analysis, Characteristics, and Simulation of Digital QAM

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Nikolaos Voudoukis
Keyword(s):  
Performance Analysis ◽  
Bit Error Rate ◽  
Error Rate ◽  
Amplitude Modulation ◽  
Performance Indicators ◽  
Digital Transmission ◽  
Quadrature Amplitude Modulation ◽  
Radio Communications ◽  
Awgn Channel ◽  
Data Rates

Quadrature Amplitude Modulation or QAM is a form of modulation which is widely used for modulating data signals onto a carrier used for radio communications. QAM, when used for digital transmission for radio communications applications is able to carry higher data rates than ordinary amplitude modulated schemes and phase modulated schemes. This paper presents the various fields where QAM can be implemented, describes modulator/demodulator block diagrams for transmitters as well as receivers, provides an introduction of certain performance indicators of modulation and a list of applications using alternative implementations of QAM. Also the paper presents a simulation of QAM using Simulink (example of 16-QAM signal) with signal trajectors and constellation plots. It is compared the theoretical and simulated Bit Error Rate (BER) for 16-QAM with Gray coding in an AWGN channel. Some general conclusions are also cited.

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