scholarly journals Theoretical and Experimental Investigation of Direct Detection Optical OFDM Systems with Clipping and Normalization

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jiang Wu ◽  
Zhongpeng Wang
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Single Mode ◽  
Superior Performance ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Transmission Scheme ◽  
Awgn Channel ◽  
Ofdm Signal ◽  
Optical Ofdm

A data clipping and normalization technique is employed to improve the performance of the overall direct detection optical orthogonal frequency division multiplexing (DCO-OFDM) system. A detailed analysis of clipping distortion introduced by digital clipping and normalization is provided. The normalization operation amplifies the clipped data signal to the maximum input amplitude of a digital-to-analog converter (DAC). Based on the analysis, a BER formula of the proposed scheme is derived over the AWGN channel and single fiber channel. Performance of an optical clipped OFDM with normalization is assessed through numerical simulations and Monte Claro simulation over the AWGN channel. Theoretical analysis and simulation results both show that the clipping and normalization scheme can greatly improve the BER of an optical OFDM. In particular, BER performance of the proposed transmission scheme was measured in a practical OFDM transmission platform. The measured experimental results show that the clipped and amplified OFDM signal exhibits superior performance in comparison with the conventional OFDM signal. The received sensitivity at a BER of 10−3 for a 4 Gsamples/s (2.6667 Gbits/s) clipped and normalized OFDM signal with clipping ratio of 4 after 100 km standard single-mode fiber (SMF) transmission was improved by 4.3 dB when compared with the conventional OFDM system. The measured results also showed that the clipped OFDM signal exhibits superior performance in comparison with the conventional OFDM signal. Therefore, a clipping and normalization at the transmitter is most effective, and a substantial performance improvement can be obtained by a simple normalization after clipping.

Hadamard Transform Combined with PTS for PAPR Reduction in Direct-Detection Optical OFDM System

2014 ◽  
Vol 1061-1062 ◽  
pp. 1194-1197
Author(s):  
Hui Li ◽  
Xu Zhang ◽  
Lei Guo ◽  
Ye Jun Liu ◽  
Xiao Xue Gong ◽  
...  
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Average Power ◽  
Papr Reduction ◽  
Hadamard Transform ◽  
Ofdm System ◽  
Partial Transmit Sequence ◽  
Ofdm Signal ◽  
Optical Ofdm ◽  
Complementary Techniques

High Peak-to-Average Power Ratio (PAPR) of the Orthogonal Frequency Division Multiplexing (OFDM) signal is one of the limitations to the transmission performance of optical OFDM system. In this paper, we propose a novel hybrid PAPR reduction technique called Hadamard Transform Combined with Partial transmit sequence (HTCP). The proposed HTCP scheme combines the merits of two complementary techniques, i.e., Hadamard transform and Partial Transmit Sequence (PTS), to improve the performance of the optical OFDM system in terms of PAPR and Bit Error Rate (BER). Simulation results show that the HTCP scheme has better performance with regard to PAPR and BER compared with the case of applying only the Hadamard transform or PTS technique.

An Improved Frame Synchronization for Optical OFDM Systems

2012 ◽  
Vol 571 ◽  
pp. 646-650
Author(s):  
Meng Liang ◽  
Rong Lu ◽  
Yuan Bo Wang ◽  
Jia Min Gong
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Dispersion Compensation ◽  
Critical Factor ◽  
Timing Synchronization ◽  
Frame Synchronization ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Transmission Distance ◽  
Optical Ofdm

Orthogonal frequency division multiplexing (OFDM) is applied to optical communication widely because of its robustness against channel dispersion and high spectral efficiency. But the synchronization between transmitter and receiver is a critical factor for system performances. This paper proposes an improved frame timing synchronization algorithm for optical OFDM system to keep synchronization by delay time compensation. The simulation of 40 Gb/s single-side-band (SSB) direct-detection optical OFDM system is setup and investigated. The curve of timing metric and the constellation of four-quadrature amplitude modulation (QAM) are given in the paper. And the transmission distance using the proposed method is compared with Park method. The simulation results show that the improved frame synchronization method promote the performances of optical OFDM system greatly. The distance can be 1600 km without dispersion compensation under the bit error ratio of 10-4.

Generalized Trapezoidal Companding Technique for PAPR Reduction in OFDM Systems

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Saruti Gupta ◽  
Ashish Goel
Keyword(s):  
Bit Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Frequency Division ◽  
Performance Parameters ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Ofdm Signal ◽  
Specific Degree ◽  
Ofdm Signals

Abstract The main drawback in the performance of the Orthogonal Frequency Division Multiplexing (OFDM) system is the higher Peak-to-Average Power Ratio (PAPR) of the OFDM signals at the transmitter side. Companding is a well-known technique useful for reducing PAPR in the OFDM signal. This paper proposes a new nonlinear companding scheme that transforms the magnitude of Rayleigh distributed OFDM signal of specific degree into trapezoidal distribution. Additional design parameter is used in the proposed companding scheme to make the companding function more flexible. In the designed OFDM system the companding function has more degree of freedom which improves the PAPR and bit error rate (BER) parameters of the designed system. It has been demonstrated that the designed companding scheme provides more flexibility to accomplish an optimum trade-off between the performance parameters PAPR and BER of the designed OFDM system.

Efficient Blind Adaptive CSE to Reduce Cyclic Prefix Length in Direct Detection Optical OFDM Systems

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Asmaa Benieddi ◽  
Sid Ahmed Elahmar
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Group Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Single Mode ◽  
Optical Signal ◽  
Single Mode Fiber ◽  
Cyclic Prefix ◽  
Ofdm Systems ◽  
Blind Adaptive

AbstractDirect detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems for a long-reach of standard single mode fiber (SSMF) require a large length of cyclic prefix (CP) to avoid the inter-symbol interference (ISI) effect caused by group velocity dispersion (GVD). Unfortunately, this method is inefficient due to the energy wasted in CP samples. In order to reduce the CP length and to mitigate the residual ISI, a novel blind adaptive channel shortening equalizer (CSE) is proposed in this paper. Based on the orthogonality between subcarriers in the fast Fourier transform (FFT) property, the proposed algorithm attempts to minimize the sum-squared correlation (SSCM) between each sample located in a well-defined window to update the CSE coefficients. Thus, the combined channel-CSE response is shortened. Therefore, it can cancel the residual ISI effect due to the GVD and the short CP length. The performance of the system is evaluated on basis of bit error rate (BER) versus optical signal to noise ratio (OSNR) for different CP lengths. The simulation results validate the new algorithm SSCM and show that it can reduce the CP length with a much better system improvement than existing algorithms.

scholarly journals A Scaling Scheme for DCT Precoded Optical Intensity-Modulated Direct Detection Systems

2015 ◽  
Vol 2015 ◽  
pp. 1-10
Author(s):  
Zhongpeng Wang ◽  
Xiumin Wang ◽  
Fangni Chen ◽  
Weiwei Qiu ◽  
Linpeng Ye
Keyword(s):  
Dynamic Range ◽  
Direct Detection ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Optical Intensity ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Digital To Analog Converter ◽  
Intensity Modulated ◽  
Ber Performance

A scaling technique is employed to improve the performance of a Discrete Cosine Transform (DCT) precoded optical intensity-modulated direct detection (IM/DD) OFDM system, which fully exploits the dynamic range of a digital-to-analog converter (DAC). The theoretical analysis shows that the proposed scaling scheme can improve the BER performance of DCT precoded and scaled OFDM systems. The experiment results also show that the proposed scheme significantly improves the BER performance without changing the receiver structure. The measured received sensitivity at a BER of 10−3for a 4 G samples/s (2.7 Gbits/s) DCT precoded and scaled OFDM signal and after 100 km standard single-mode fiber (SMF) transmission has been improved by 3 and 1.3 dB when compared with the original OFDM system and conventional DCT precoded OFDM system, respectively.

PAPR Reduction for O-OFDM UOWC System

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Jurong Bai ◽  
Hang Dai ◽  
Feng Zhao ◽  
Yi Yang ◽  
Yanben Wang
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Optical Transition ◽  
Average Power ◽  
Maximum Amplitude ◽  
Ofdm System ◽  
Wireless Optical Communication ◽  
Speed Up ◽  
Optical Ofdm ◽  
Papr Performance

AbstractIn this paper, a combination of Tone Reservation-Signal to Clipping noise Ratio (TR-SCR) and Companding schemes is proposed for underwater wireless optical communication (UOWC), in order to solve the problem of high peak-to-average power ratio (PAPR) of underwater Optical-Orthogonal Frequency Division Multiplexing (O-OFDM) system. Two optical modulation schemes, namely Direct Current-biased Optical OFDM (DCO-OFDM) and Asymmetrically Clipped Optical OFDM (ACO-OFDM), are adopted separately to achieve intensity modulation/direct detection over the seawater channel, with a distance of 100 meters of wireless optical transition to obtain the system bit error rate (BER). In the TR-SCR scheme, only the maximum amplitude signal is selected to reduce the complexity of the algorithm. The LSA method is introduced in the TR-SCR scheme for iteratively updating the signal to speed up the convergence. Finally, with the combination of the Companding scheme, the PAPR performance is significantly improved. The PAPR of the underwater optical OFDM system is reduced to 3.85 dB with its BER still satisfying the UOWC system requirements.

scholarly journals Extended Reach 10 Gb/s Transmission with an Optical I/Q Modulator Using VCSELs over OFDM-Based Multimode Fiber Link

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Deepak Kedia ◽  
Monika Nehra
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Cavity Surface ◽  
Multimode Fiber ◽  
Ofdm System ◽  
Worst Case ◽  
Modulation Technique ◽  
Ofdm Signal ◽  
Vertical Cavity Surface ◽  
Emitting Lasers

This paper investigates the possibilities of extending the reach of a 10 Gb/s orthogonal frequency division multiplexing- (OFDM-) based multimode fiber (MMF) link with an optical I/Q modulation technique through vertical cavity surface emitting lasers (VCSELs). The proposed I/Q modulation technique comprises two VCSELs in a 90° hybrid combination to produce I/Q modulated OFDM signal. The results show the excellent performance (in terms of BER and Q factor) of the direct-detection optical- (DDO-) OFDM system with the proposed I/Q modulation in comparison to the direct modulation case. The proposed system is able to achieve worst-case BER of about 1.8616 × 10−3 and Q factor of about 10.9949 dB over a 5 km MMF link. The I/Q modulation technique in the DDO-OFDM system has further been investigated for extending the transmission reach of the MMF link using multispan configuration.

scholarly journals A New-Trend Model-Based to Solve the Peak Power Problems in OFDM Systems

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Ashraf A. Eltholth ◽  
Adel R. Mekhail ◽  
A. Elshirbini ◽  
M. I. Dessouki ◽  
A. I. Abdelfattah
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Peak Power ◽  
Dynamic Range ◽  
Average Power ◽  
Problem Definition ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Ofdm Signal ◽  
Nonlinear Amplifier ◽  
Power Problem

The high peak to average power ration (PAR) levels of orthogonal frequency division multiplexing (OFDM) signals attract the attention of many researchers during the past decade. Existing approaches that attack this PAR issue are abundant, but no systematic framework or comparison between them exists to date. They sometimes even differ in the problem definition itself and consequently in the basic approach to follow. In this paper, we propose a new trend in mitigating the peak power problem in OFDM system based on modeling the effects of clipping and amplifier nonlinearities in an OFDM system. We showed that the distortion due to these effects is highly related to the dynamic range itself rather than the clipping level or the saturation level of the nonlinear amplifier, and thus we propose two criteria to reduce the dynamic range of the OFDM, namely, the use of MSK modulation and the use of Hadamard transform. Computer simulations of the OFDM system using Matlab are completely matched with the deduced model in terms of OFDM signal quality metrics such as BER, ACPR, and EVM. Also simulation results show that even the reduction of PAR using the two proposed criteria is not significat, and the reduction in the amount of distortion due to HPA is truley delightful.

Experimental Investigation of Intensity Modulator/Direct Detection (IM/DD) Optical OFDM System with Fiber Bragg Grating (FBG)

2020 ◽  
Vol 41 (3) ◽  
pp. 257-262
Author(s):  
Papa Alioune FALL ◽  
Mangone Fall
Keyword(s):  
Fiber Bragg Grating ◽  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Dispersion Compensation ◽  
Chromatic Dispersion ◽  
Regular System ◽  
Bragg Grating ◽  
Intensity Modulator ◽  
Ofdm Signal ◽  
Optical Ofdm

AbstractTo improve the performance of optical fiber transmission and to compensate the fiber chromatic dispersion (CD), we propose to use fiber Bragg grating (FBG) in intensity modulator/direct detection IM/DD optical orthogonal frequency division multiplexing (OOFDM) system, and experimentally demonstrate 2.5-Gbit/s QPSK-OFDM transmission over 200 km SMF-28. FBG used before the detection as a chromatic dispersion compensation module, reducing the beating noise between ASE noise and OFDM signal. By using the FBG in IM/DD OOFDM system, our experimental results show that the receiver sensitivity was improved about 2 dB at a bit error rate (BER) of $1 \times {10^{ - 3}}$ for 2.5 Gbit/s QPSK-OFDM signals after 200 km SMF-transmission compared to regular system without FBG.

scholarly journals A Novel Hybrid Block INF Diagonalization (HBID) Precoding Technique for Capacity Improvement in MU-MIMO-OFDM System

2019 ◽  
Vol 9 (1) ◽  
pp. 5369-5375
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Mimo System ◽  
Multiple Input Multiple Output ◽  
Average Power ◽  
Threshold Value ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Transmission Scheme ◽  
Mimo Ofdm ◽  
Sum Rate

In wireless communication system, the emerging technology is MU-Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MU-MIMO-OFDM). For minimizing Peak-to-Average Power Ratio (PAPR) in the uplink transmission scheme, OFDM is exploited in MIMO system and compared with Single Carrier-Frequency Domain Processing (SC-FDP). Further reducing the PAPR value, a new method is proposed Hybrid Block Inf Diagonalization (HBID) technique for an uplink OFDM system and calculated the less Bit Error Rate (BER). In this paper, the HBID precoding technique reduces PAPR with such amount and unwanted amplitude of the signal is to be cut down for a specific threshold value as 1.4 for best performance so that the PAPR value is reduced in considerable rate of OFDM then compared to SC-FDP system. Also, we compared the various precoding techniques with HBID method in MIMO-OFDM systems with various parameters such as BER, PAPR, Number of users, Sum rate. Finally, the proposed method reduces PAPR with 47% and BER with 50%, number of users with 49% and sum rate as 57%. HBID based precoding method shows its excellence with the lowest PAPR value and thereby enhance the presentation of the OFDM system

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