scholarly journals Design of Nonequiprobable High-Order Constellations over Non-Linear Satellite Channels

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 123
Author(s):  
Weigang Chen ◽  
Yu Peng ◽  
Changcai Han ◽  
Jinsheng Yang
Keyword(s):  
Communication Systems ◽  
Mapping Method ◽  
Linear Mapping ◽  
High Order ◽  
Bandwidth Efficiency ◽  
Performance Improvements ◽  
Non Linear ◽  
Satellite Channels ◽  
Linear Effects ◽  
Simulation Results

High-order modulations are essential to improve the bandwidth efficiency of communication systems. However, such modulated signals with large envelopes are typically sensitive to the non-linear distortion caused by high power amplifiers (HPAs) in the transponder of satellite channels. In this paper, a new nonequiprobable constellation is designed to combat the non-linear effects of HPAs. We use non-uniformly distributed symbols to construct the appropriate high-order constellation for non-linear satellite channels. The nonequiprobable symbols are generated using the non-linear mapping method, which specifically consists of expansion mapping, symbol decomposition, permutation, and combination. Moreover, the demapping method adapting to the designed nonequiprobable constellation is also discussed. The simulation results show that the proposed scheme has considerable performance improvements compared with the traditional equiprobable constellations over the non-linear satellite channel.

scholarly journals Combination of High-Order Modulation and Non-Binary LDPC Codes over GF(7) for Non-Linear Satellite Channels

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1396 ◽  
Author(s):  
Yanyan Liu ◽  
Weigang Chen ◽  
Anguo Wang ◽  
Changcai Han
Keyword(s):  
Communication System ◽  
Satellite Communication ◽  
Additive White Gaussian Noise ◽  
Ldpc Codes ◽  
High Order ◽  
Modulation Scheme ◽  
Satellite Communication System ◽  
Awgn Channel ◽  
Non Linear ◽  
Satellite Channels

High-order modulations are necessary to improve the bandwidth efficiency of the satellite communication system. However, the non-linear characteristic of satellite channels limits the application of high-order modulations. In this paper, we propose a new 7-point constellation which is expected to be effectively applied to the satellite communication system, and combine it with non-binary low-density parity-check (NB-LDPC) codes over Galois field GF(7) to guarantee the reliability of the data transmission. The exact expression for the average symbol error probability (SEP) of 7-order quadrature amplitude modulation (7-QAM) over the Additive White Gaussian Noise (AWGN) channel is derived, and the non-linear distortion over satellite channels is also analyzed. Simulation results reveal that, compared with the traditional 8-order phase-shift keying (8-PSK), the 7-QAM method can achieve about 3 dB gain over the AWGN channel without channel coding at symbol error rate (SER) of 10 - 6 . Moreover, the proposed combined coded modulation scheme also has better SER performance than the NB-LDPC coded 8-PSK modulation scheme over the non-linear satellite channel.

scholarly journals A Comparative Study of SPM, XPM in Er-Yb Co-doped Fiber

2021 ◽  
Author(s):  
ADITYA KUMAR ◽  
Gausia Qazi
Keyword(s):  
Optical Fiber ◽  
Comparative Study ◽  
Phase Modulation ◽  
Communication Systems ◽  
Optical Fiber Communication ◽  
Optical Systems ◽  
Fiber Communication ◽  
Non Linear ◽  
Linear Effects ◽  
Co Doped

Optical fiber communication has been the most versatile and revolutionary medium of communication that has helped in connecting millions of people across the globe. These traits have seen tremendous development in the sector of optical fiber communication. There are now many desired qualities that are expected out of an optical fiber communication like large transmission capacity and a lesser amount of losses. Communication systems operating with higher transmission rates have found an essential role of non-linear fiber optics. The behaviour of light in non-linear media is dealt with non-linear optics. Cross-Phase Modulation (XPM) and Self-Phase Modulation (SPM) are a few non-linearities occurring in the optical fiber. Non-linear effects reduce the performances of optical fibers. In this paper, a comparative study of non-linear effects in Er-Yb co-doped Fiber are reviewed using simulation and the results are compared with optical systems utilizing normal fiber. Benefits of utilizing Er-Yb fiber has been demonstrated by analysing effective systems comprising the Er-Yb co-doped fiber and their ability to mitigate the non-linearities.

Fault Tree Analysis for a Modern Communication System

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Kamal Hamid ◽  
Nadim Chahine
Keyword(s):  
Communication System ◽  
Communication Systems ◽  
Fault Tree ◽  
Fault Tree Analysis ◽  
Theory And Practice ◽  
Tree Analysis ◽  
Satisfactory Performance ◽  
System Components ◽  
Link Budget ◽  
Simulation Results

Wireless communications became one of the most widespread means for transferring information. Speed and reliability in transferring the piece of information are considered one of the most important requirements in communication systems in general. Moreover, Quality and reliability in any system are considered the most important criterion of the efficiency of this system in doing the task it is designed to do and its ability for satisfactory performance for a certain period of time, Therefore, we need fault tree analysis in these systems in order to determine how to detect an error or defect when happening in communication system and what are the possibilities that make this error happens. This research deals with studying TETRA system components, studying the physical layer in theory and practice, as well as studying fault tree analysis in this system, and later benefit from this study in proposing improvements to the structure of the system, which led to improve gain in Link Budget. A simulation and test have been done using MATLAB, where simulation results have shown that the built fault tree is able to detect the system’s work by 82.4%.

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