Robust Channel Estimation for Coherent Optical Orthogonal Chirp-Division Multiplexing With Pulse Compression and Noise Rejection

Ouyang, Xing; Antony, Cleitus; Talli, Giuseppe; Townsend, Paul D.

doi:10.1109/jlt.2018.2877305

Cited by 31 publications

(18 citation statements)

References 28 publications

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“…As discussed in Section II, for obtaining a proper reflectogram from the discrete-Fresnel domain vector ẏ, the influence of the discrete-Fresnel domain transmit vector ẋ on it as expressed in (3) must be minimized or ideally removed. Considering that a single PLM performs sensing of the power distribution network, a transmit vector ẋ constituted of pilots spaced by L ρ samples in the discrete Fresnel domain can be used [18], [19]. Thus, the k th element of ẋ will be given by ẋk =…”

Section: Distributed Power Line Sensingmentioning

confidence: 99%

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Orthogonal Chirp-Division Multiplexing for Power Line Sensing via Time-Domain Reflectometry

et al. 2021

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In this study, a time-domain reflectometry (TDR) system based on a baseband version of the orthogonal chirpdivision multiplexing (OCDM) scheme, which is relies on a modified discrete Fresnel transform (DFnT), is proposed for power line sensing. After a detailed description of the system model, a multiple access scheme that exploits the contolution theorem of the modified DFnT for enabling distributed reflectometric and transferometric sensing of the monitored power line. Considering typical European underground low-voltage and US overhead medium-voltage (MV) power distribution networks, range resolution and maximum unambiguous range for the measurements are assessed for the proposed scheme. Next, a comparison with multiple access schemes based on the Hermitian symmetric orthogonal frequency-division multiplexing (HS-OFDM) discussed in a previous work is performed considering a Brazilian MV overhead scenario, being the number of measurements obtained over time, as well as signal-to-interference-plusnoise ratio (SINR) used as performance metrics. The attained results show that the proposed multiple access scheme results in the same range resolution as the others. Also, the highest number of measurements over time is obtained by the proposed scheme, which produces orthogonality among signals transmitted by different power line modems (PLMs) neither and time nor frequency domains, but rather in the Fresnel domain. Meanwhile, although its yielded SINR values are fair among the PLMs consisting the distributed sensing system, the proposed scheme is slightly outperformed by the HS-OFDM based on code-division multiple access and by the HS-OFDM based on frequencydivision multiple access at some PLMs.Index Terms-Time-domain reflectometry, orthogonal chirpdivision multiplexing, multiple access, power line communication.

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Section: Distributed Power Line Sensingmentioning

confidence: 99%

“…in which Z ∈ R 2N ×2N is a circulant matrix. The proof for (19) starts by rearranging the expression as…”

Section: Similarity Transformation Of the Modified Dfntmentioning

confidence: 99%

Orthogonal Chirp-Division Multiplexing for Power Line Sensing via Time-Domain Reflectometry

et al. 2021

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“…OCDM's (inverse) discrete Fresnel transform ((I)DFnT) -required to achieve orthogonality in the chirp domain -can be synthesized utilizing the (I)DFT as a basis; offering ease of integration with existing OFDM digital signal processing (DSP). In [6], we proposed the use of a chirped signal, obtained directly from OCDM's DFnT, as a pilot symbol for CE. By exploiting the PC properties of this chirped pilot, the channel state information (CSI) can be estimated at the receiver.…”

Section: Orthogonal Chip-division Multiplexing and Enhanced Channel E...mentioning

confidence: 99%

“…Previously, we have proposed orthogonal chirp-division multiplexing (OCDM) as a novel waveform which, compared to OFDM, offers increased robustness to the severe multi-path impairments due its unique chirp spread-spectrum form [5]. In addition, OCDM's discrete implementation readily facilitates superior receiver channel estimation (CE) and equalization (EQ) [6]. Because of these advantages, recent works have assessed OCDM's performance favorably in both optical transport [6] and wireless [7] systems.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, OCDM's discrete implementation readily facilitates superior receiver channel estimation (CE) and equalization (EQ) [6]. Because of these advantages, recent works have assessed OCDM's performance favorably in both optical transport [6] and wireless [7] systems. In [8], the authors highlight OCDM's tolerance to wireless mm-wave interference in an A-RoF system which includes a photo-generated mm-wave signal.…”

Section: Introductionmentioning

confidence: 99%

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Orthogonal Chirp-Division Multiplexing for Performance Enhanced Optical/Millimeter-Wave 5G/6G Communications

Browning

Ouyang²,

Dass

et al. 2021

Optical Fiber Communication Conference (OFC) 2021

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Peak to average power ratio reduction techniques based on chirp selection for single and multi‐user orthogonal chirp division multiplexing system

Savaux

2023

IET Signal Processing

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This article deals with peak to average power (PAPR) reduction in a single and multi-user orthogonal chirp division multiplexing (OCDM) context. Two methods for PAPR reduction based on the selection of the frequency variation (up or down) of the chirps are first presented in a single user system. The first technique consists in considering two OCDM signals generated with up and down chirps, respectively, and selecting the one offering lowest PAPR. The second PAPR reduction method is based on usual clipping, and in that case the chirp selection aims to reduce the clipping noise. An adapted receiver is presented, based on the maximum likelihood estimation of the frequency variation (up or down) of the chirp. Then, a general procedure for multi-user OCDM transmission is introduced, where a sub-band of the available bandwidth is dedicated to each user, whose frequency of the chirps varies within this sub-band. Next, the PAPR reduction techniques are generalised to this multi-user OCDM system. Moreover, a performance analysis of the first PAPR reduction method is developed, and it is shown through simulations that theoretical and numerical results match for both Nyquist rate and oversampled signals. It is also shown that the chirp selection reduces the clipping noise, and improves the bit error rate performance compared with clipping only. K E Y W O R D S 5G mobile communication, digital communication, power amplifiers | INTRODUCTIONOrthogonal chirp division multiplexing (OCDM) is an emerging waveform which is based on Fresnel transform instead of Fourier transform in orthogonal frequency division multiplexing (OFDM) [1]. The main advantage of OCDM against OFDM or transform precoded OFDM, such as discrete Fourier transform-spread-OFDM (DFT-s-OFDM) used in 5G [2], lies in the fact that OCDM achieves an optimal decoding of the received signal in presence of time and frequency selective channels [3], whereas OFDM (resp. precoded OFDM) is only sub-optimal against frequency selective channel (resp. time selective channels) [4]. The optimality of OCDM is inherent to the use of chirps that spread the possible errors over the time and frequency grid. Furthermore, the use of chirps could be also relevant in the context of sensing and communications in 6G [5], since chirps are originally used in radar applications [6]. Another advantage inherent to OCDM is that it is backward compatible with OFDM-like waveforms used in numerous standards and technologies [7] such as WiFi, 4/5G etc., as it has been shown in refs. [7,8] that the OCDM is equivalent to the OFDM modulation scheme, precoded with a DFT matrix and a multiplication by a chirp.The high robustness against time and frequency selective channels is also a benefit of the orthogonal time frequency space modulation [9] and the affine function division multiplexing [10,11]. Although both waveforms can actually achieve 'full diversity' against multipath mobile channels [10], unlike OCDM, they are not backward compatible with OFDM-like signals as they require dedicated transmitter...

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Robust Channel Estimation for Coherent Optical Orthogonal Chirp-Division Multiplexing With Pulse Compression and Noise Rejection

Cited by 31 publications

References 28 publications

Orthogonal Chirp-Division Multiplexing for Power Line Sensing via Time-Domain Reflectometry

Orthogonal Chirp-Division Multiplexing for Power Line Sensing via Time-Domain Reflectometry

Orthogonal Chirp-Division Multiplexing for Performance Enhanced Optical/Millimeter-Wave 5G/6G Communications

Peak to average power ratio reduction techniques based on chirp selection for single and multi‐user orthogonal chirp division multiplexing system

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