scholarly journals Residual Clipping Noise in Multi-layer Optical OFDM: Modeling, Analysis, and Application

2020 ◽  
Author(s):  
Zhenyu Zhang ◽  
Anas Chaaban ◽  
Mohamed-Slim Alouini
Keyword(s):  
Spectral Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Single Layer ◽  
Symbol Error Rate ◽  
Frequency Division ◽  
Accurate Evaluation ◽  
Accurate Model ◽  
Modeling Analysis ◽  
Symbol Detection ◽  
Optical Ofdm

Optical orthogonal frequency division multiplexing (O-OFDM) schemes are variations of OFDM schemes which produce non-negative signals. Asymmetrically-clipped O-OFDM (ACO-OFDM) is a single-layer O-OFDM scheme, whose spectral efficiency can be enhanced by adopting multiple ACO-OFDM layers or a combination of ACO-OFDM and other O-OFDM schemes. However, since symbol detection in such enhanced ACO-OFDM (eACO-OFDM) is done iteratively, erroneous detection leads to residual clipping noise (RCN) which can degrade performance in practice. Thus, it is important to develop an accurate model for RCN which can be used to design RCN-aware eACO-OFDM schemes. To this end, this paper provides a mathematical analysis of RCN leading to an accurate model of RCN power. The obtained model is used to analyze the performance of various eACO-OFDM schemes. It is shown that the model provides an accurate evaluation of symbol error rate (SER), which would be underestimated if RCN is ignored. Moreover, the model is shown to be useful for designing an RCN-aware resource allocation that increases the robustness of the system in terms of meeting a target SER, compared to an RCN-unaware design.

scholarly journals Residual Clipping Noise in Multi-layer Optical OFDM: Modeling, Analysis, and Application

2020 ◽  
Author(s):  
Zhenyu Zhang ◽  
Anas Chaaban ◽  
Mohamed-Slim Alouini
Keyword(s):  
Spectral Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Single Layer ◽  
Symbol Error Rate ◽  
Frequency Division ◽  
Accurate Evaluation ◽  
Accurate Model ◽  
Modeling Analysis ◽  
Symbol Detection ◽  
Optical Ofdm

Optical orthogonal frequency division multiplexing (O-OFDM) schemes are variations of OFDM schemes which produce non-negative signals. Asymmetrically-clipped O-OFDM (ACO-OFDM) is a single-layer O-OFDM scheme, whose spectral efficiency can be enhanced by adopting multiple ACO-OFDM layers or a combination of ACO-OFDM and other O-OFDM schemes. However, since symbol detection in such enhanced ACO-OFDM (eACO-OFDM) is done iteratively, erroneous detection leads to residual clipping noise (RCN) which can degrade performance in practice. Thus, it is important to develop an accurate model for RCN which can be used to design RCN-aware eACO-OFDM schemes. To this end, this paper provides a mathematical analysis of RCN leading to an accurate model of RCN power. The obtained model is used to analyze the performance of various eACO-OFDM schemes. It is shown that the model provides an accurate evaluation of symbol error rate (SER), which would be underestimated if RCN is ignored. Moreover, the model is shown to be useful for designing an RCN-aware resource allocation that increases the robustness of the system in terms of meeting a target SER, compared to an RCN-unaware design.

scholarly journals Spectrally efficient optical orthogonal frequency division multiplexing

2020 ◽  
Vol 378 (2169) ◽  
pp. 20190180 ◽  
Author(s):  
Arthur James Lowery
Keyword(s):  
Spectral Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Fourier Transforms ◽  
Direct Detection ◽  
Optical Signal ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Optical Source ◽  
Optical Ofdm ◽  
Spectrally Efficient

This paper charts the development of spectrally efficient forms of optical orthogonal frequency division multiplexing (OFDM) that are suited for intensity-modulated direct detection systems, such as wireless optical communications. The journey begins with systems using a DC-bias to ensure that no parts of the signal that modulates the optical source are negative in value, as negative optical intensity is unphysical. As the DC-part of the optical signal carries no information, it is wasteful in energy; thus asymmetrically clipped optical OFDM was developed, removing any negative-going peaks below the mean. Unfortunately, the clipping causes second-order distortion and intermodulation, so some subcarriers appear to be unusable, halving spectral efficiency; this is similar for unipolar and flipped optical OFDM. Thus, a considerable effort has been made to regain spectral efficiency, using layered techniques where the clipping distortion is mostly cancelled at the receiver, from a knowledge of one unpolluted layer, enabling one or more extra ‘layers/paths/depths’ to be received on the previously unusable subcarriers. Importantly, for a given optical power and high-order modulation, layered methods offer the best spectral efficiencies and need the lowest signal-to-noise ratios, especially if diversity combining is used. Thus, they could be important for high-bandwidth optical fibre systems. Efficient methods of generating all layers simultaneously, using fast Fourier transforms with their partial calculations extracted, are discussed, as are experimental demonstrations in both wireless and short-haul communications links. A musical analogy is also provided, which may point to how orchestral and rock music is deciphered in the brain. This article is part of the theme issue ‘Optical wireless communication’.

scholarly journals Spectral Efficiency of FBMC Over OFDM System

2019 ◽  
Vol 9 (2S3) ◽  
pp. 235-237
Keyword(s):  
Spectral Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Filter Bank ◽  
Average Power ◽  
Primary Objective ◽  
Mobile Environments ◽  
Frequency Division ◽  
Doppler Shifts ◽  
Wireless Broadband ◽  
High Spectral Efficiency

Significant wireless broadband technology used in various cellular standards is Orthogonal Frequency Division Multiplexing (OFDM) which will make use of Multi Carrier Modulated (MCM) systems. Even though OFDM has numerous advantages, it is hard to employ OFDM for complex networks. It is very hard to establish synchronization in mobile environments as it is difficult to predict the Doppler shifts of different users, which results in inter carrier interference (ICI). Further, filters associated with OFDM carrier have comparatively large sidebands which outcomes in Out of Band (OOB) radiations. Insufficient spectral usage is provided by CP-OFDM by using more guard band. So the problems caused by traditional OFDM/CP-OFDM can be answered by employing a new system termed as Filter Bank Multi Carrier (FBMC) System. It is a form of MCM and it can be considered as an advanced cyclic-prefix (CP-OFDM). In OFDM, whole band gets filtered while in FBMC, each sub carrier band is independently filtered. The primary objective of this work is to relate the performance of 5G modulation technique such as FBMC against OFDM and to suggest an ideal waveform for 5G communication in regard to high spectral efficiency, spectral density, BER and less Peak to Average Power Ratio (PAPR).

Key Technologies for Optical OFDM in Optical Long-Haul System Using Direct-Detection

2015 ◽  
Vol 719-720 ◽  
pp. 845-850
Author(s):  
Yi Tang ◽  
Ping Xing Feng
Keyword(s):  
Theoretical Model ◽  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Single Sideband ◽  
Key Technologies ◽  
Optical Single Sideband ◽  
Optical Ofdm

A comprehensive theoretical model of direct detection (DD) optical orthogonal frequency division multiplexing (OOFDM) system is described in general. The principle of OOFDM is introduced in detail. Several key technologies in DD-OOFDM system have been discussed. The advantages and methods for optical single sideband (OSSB) and channel estimation are analyzed completely. Other key technologies are introduced briefly.

scholarly journals BER performance study for optical OFDM of optical camera communication

2021 ◽  
Vol 11 (5) ◽  
pp. 4263
Author(s):  
Noor J. Jihad ◽  
Sinan M. Abdul Satar
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Signal To Noise Ratio ◽  
Frequency Division ◽  
Performance Study ◽  
Mapping Rule ◽  
Bit Loading ◽  
Dc Bias ◽  
Optical Ofdm ◽  
Ber Performance ◽  
Optical Camera Communication

In this article, different forms of optical orthogonal frequency division multiplexing (OFDM) were observed which were suitable for optical camera communication (OCC) systems. This research aims to establish the bit error rate (BER) versus signal-to-noise ratio (SNR) of the OCC system. This research will focus on OCC systems and the design that produces the noise of the clipping but will gain SNR as a whole if an optimum clipping factor is chosen. The BER versus SNR analysis was investigated for the different clipping factors 0.7, 1.4, and 2.6. The BER performance of the asymmetrically clipped optical OFDM (ACO-OFDM) was also compared with the direct current optical OFDM (DCO-OFDM) to show the suitable effectiveness of the proposed approach. ACO-OFDM was considered to be better due to lower bit loading, but DCO-OFDM was efficient for higher SNR values. This was because the DC bias used was inefficient in terms of optical capacity, while ACO-OFDM used only half of the subcarriers to transmit the information. Moreover, ACO-OFDM two-dimensional half-subcarriers of mapping rule would introduce the clipping noise to its unused 2D subcarriers, although further data can be provided by the 2D DCO-OFDM mapping rule.

Comparison and Analysis of DCO-OFDM, ACO-OFDM and ADO-OFDM in IM/DD Systems

2014 ◽  
Vol 701-702 ◽  
pp. 1059-1062 ◽  
Author(s):  
Xu Zhang ◽  
Yu Fang Zhou ◽  
Yin Peng Yu ◽  
Peng Chao Han ◽  
Xiao Rui Wang
Keyword(s):  
Optical Communication ◽  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Optical Power ◽  
Frequency Division ◽  
Optical Efficiency ◽  
Power Efficient ◽  
Optical Ofdm ◽  
And Performance ◽  
Ofdm Signals

As a promising modulation technology for optical communication, Orthogonal Frequency Division Multiplexing (OFDM) is now increasingly used and a lot of ways of improving the optical efficiency of Intensity Modulated/ Direct Detection (IM/DD) systems have been proposed. And real and non-negative OFDM signals are required in this kind of system. Asymmetrically clipped DC biased Optical OFDM (DCO-OFDM), Asymmetrically Clipped Optical OFDM (ACO-OFDM) and Asymmetrically clipped DC biased Optical OFDM (ADO-OFDM) can satisfy this requirement. In this paper, we analysis the properties and performance orderly of the above three systems and simultaneously compare their performance. The simulation results show that DCO-OFDM is efficient in terms of bandwidth while the ACO-OFDM is efficient in terms of optical power. More importantly, ADO-OFDM is both power-efficient and bandwidth-efficient. At the same time, a developmentally proposal for the future OFDM in IM/DD systems is put forward.

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