Simple Feedforward Carrier Phase Estimation for Optical FBMC/OQAM Systems

Experimental Demonstration of the Tradeoff Between Chromatic Dispersion and Phase Noise Compensation in Optical FBMC/OQAM Communication Systems

“…At the receiver side, the received signal, r[n], after heterodyne-detection is corrupted by zero-mean additive white Gaussian noise (AWGN) denoted by w[n], the carrier frequency offset (CFO) Δf CFO (originating from the frequency difference between the transmitter and receiver local oscillator lasers) and the PN φ[n] of linewidth Δν. The combined PN coming from transmitter and receiver lasers is modeled as a Wiener process [7] φ n [ ] as the received signal after frame synchronization. In order to build a proper receiver chain, some assumptions are made on the impairments and channel effects encountered by the received signal as follows − We assume that the remaining CFO is small (i.e., smaller than the subcarrier spacing) and constant over the FBMC symbol.…”

“…Due to the fact that, after coarse CFO compensation, there remains a residual CFO, which is normally in the range of the subcarrier frequency spacing, i.e., less than 86 MHz (as detailed later in Section V), the phase noise tracking can only guarantee to compensate for laser phase noise, whose linewidth is less than 10 MHz [7]. In order to successfully demodulate the signal, we design the training sequences for fine CFO compensation in order to get the residual CFO in the operational range of the phase noise tracking.…”

“…Several PN tracking methods have been proposed in the literature [6][7][8][9][10][11][12][13]. We are interested in blind feedforward PN compensation, as it does not require pilots that cause a reduction in spectral efficiency.…”

“…Similar to OFDM systems, ICI compensation methods often require feedback structures that may be undesirable in real-time implementations. In contrast, CPE compensation methods only need feedforward structures to still deliver a good performance [7]. We hence focus on CPE compensation methods.…”

“…Research on CPE compensation methods is very active in both wireless [6,[8][9][10] and optical communications [11][12][13]. Although the proposed algorithms for CPE compensation have proved their effectiveness, they provide a limited performance when the number of subcarriers is too high [7].…”