A combined digital linearization and channel estimation approach for IM/DD fast-OFDM systems

Vieira, Luis Carlos; Hussein, Shirin; Darwazeh, Izzat; Liu, Chin-Pang; Mitchell, John E.

doi:10.1016/j.yofte.2021.102725

Cited by 4 publications

(10 citation statements)

References 25 publications

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“…Short-reach intensity-modulation and directdetection (IM/DD) optical Fast-OFDM systems were examined by [22], and they developed combined channel estimation and digital linearization schemes. To transmit the 2PAM signals, the odd SCs of the training sequences were used.…”

Section: Literature Reviewmentioning

confidence: 99%

Highly Accurate Technique for CO-OFDM Channel Estimation Technique Using Extreme Learning Machine (ELM)

Joseph

Puttamadappa

2023

Wseas Transactions on Electronics

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In wireless systems, channel estimation is considered a problematic technology, due to the fact of the difference in time between wireless channels and the noise effect. Orthogonal frequency-division multiplexing (OFDM) is a promising candidate for future optical communications and has received wide concern. The article proposed a Coherent Optical (CO) orthogonal frequency division multiplexing (OFDM) scheme, which gives a scalable and flexible solution for increasing the transmission rate, being extremely robust to chromatic dispersion as well as polarization mode dispersion. Nevertheless, both coherent detection and OFDM are prone to phase noise due to the phase mismatch between the laser oscillators at the transmitter and receiver sides and the relatively long OFDM symbol duration compared to that of single carrier communications. An Extreme Learning Machine (ELM) with Pilot Assisted Equalization (PEM) is proposed for compensation of impairments caused by fibre nonlinearity in coherent optical communication systems. Channel estimation using ELM and the value of distortion is sent to the OSTBC receiving end based on the distortion information the data is decoded and pilot data is removed. FFT is applied to the data and QPSK demodulation is done in the data to get its original form. In addition, the article utilized a free-space optical communication system of multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) with a modified receiver structure. Simulation reveals that the proposed model exhibits significant BER (0.0112) performance and provides better spectral efficiency as compared with conventional systems and less computational complexity. This suggested that the proposed method shows better performance by using the CO-OFDM-FSO-MIMO-ELM-based channel estimation technique for high-speed data communication networks in real-time scenarios respectively.

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Section: Literature Reviewmentioning

confidence: 99%

Highly Accurate Technique for CO-OFDM Channel Estimation Technique Using Extreme Learning Machine (ELM)

Joseph

Puttamadappa

2023

Wseas Transactions on Electronics

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“…With this approach, the training can be done in only one step and in a least-squares sense, avoiding the use of sample-by-sample algorithms. In addition, as previously proposed in [4], the received training signals are also post-distorted before being used for the FFT-based channel estimation and equalization. In this way, the memoryless polynomial based post-distortion approach has also a dynamic compensation effect on the system performance.…”

Section: Distortion Compensation Approachmentioning

confidence: 99%

“…Fast-OFDM [3] is another multicarrier signal and system that has been proposed for IM/DD optical systems [4]- [7], which advantageously offers either 50% bandwidth saving or double the number of data subcarriers within the same bandwidth compared to using conventional OFDM systems. This is achieved by either compressing the frequency spacing between the subcarriers down to 1/2𝑇, where 𝑇 is the symbol duration, or sampling faster in comparison to conventional OFDM.…”

Section: Introductionmentioning

confidence: 99%

“…However, the nonlinear distortion that falls within the signal bandwidth can not be filtered out [9]. Adaptive digital predistortion and postdistortion techniques have been proposed for the compensation of nonlinear distortion in optical communication systems [4], [10]- [12]. Digital predistortion is more complex to implement than post-distortion due to the need of an additional feedback link for model identification.…”

Section: Introductionmentioning

confidence: 99%

“…We then apply the GMP-based Fast-OFDM model to investigate the performance of an amplitude clipping and polynomial post-distortion scheme for optical Fast-OFDM links. In our previous work [4], no clipping was employed at the transmitter side and a different channel estimation method was used. In addition, no modeling investigation involving either the MP or GMP model was considered.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling and compensation of nonlinear distortion in direct-detection optical Fast-OFDM systems

Vieira

Ozan

Mitchell

et al. 2022

2022 13th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP)

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Fast-OFDM based intensity-modulation and directdetection (IM/DD) has been proposed for the deployment of costefficient optical access networks, due to simple implementation and high spectral efficiency. In this work, the generalized memory polynomial (GMP) is firstly applied to model the nonlinear characteristic of IM/DD Fast-OFDM links, including memory effects. After model validation using measured data of a 10km single mode fiber link, the GMP is used for performance investigations of a combined clipping and digital post-distortion approach to optical Fast-OFDM, considering both 4PAM and 8PAM modulation formats and different number of Fast-OFDM subcarriers. This work firstly reports performance results of optical 8PAM-Fast-OFDM systems using 2PAM-based training signals for digital post-distortion and FFT-based channel estimation. Excellent performance improvements are achieved using the proposed distortion compensation scheme, relative to conventional system implementation.

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Deep learning‐based channel estimation for OFDM‐IM systems over Rayleigh fading channels

Adiguzel,

Develi

2024

Int J Communication

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SummaryDeep learning (DL)‐based channel estimation for orthogonal frequency division multiplexing with index modulation (OFDM‐IM) under Rayleigh fading channel conditions is presented in this paper. A deep neural network (DNN) is utilized to estimate the channel response in simulations. The proposed DNN is trained using the channel coefficient derived through the least squares (LS) method. Then channel estimation is conducted using the trained DNN. Within the DNN, the long short‐term memory (LSTM) layer is included as the hidden layer. Different scenarios are handled in simulations and the proposed DNN is compared with traditional channel estimation methods. The simulations demonstrate that the DL‐based channel estimation significantly surpasses the LS and minimum mean‐square error (MMSE) techniques.

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A combined digital linearization and channel estimation approach for IM/DD fast-OFDM systems

Cited by 4 publications

References 25 publications

Highly Accurate Technique for CO-OFDM Channel Estimation Technique Using Extreme Learning Machine (ELM)

Highly Accurate Technique for CO-OFDM Channel Estimation Technique Using Extreme Learning Machine (ELM)

Modeling and compensation of nonlinear distortion in direct-detection optical Fast-OFDM systems

Deep learning‐based channel estimation for OFDM‐IM systems over Rayleigh fading channels

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