Zero-overhead phase noise compensation via decision-directed phase equalizer for coherent optical OFDM

Abstract

We report and investigate the feasibility of zero-overhead laser phase noise compensation (PNC) for long-haul coherent optical orthogonal frequency division multiplexing (CO-OFDM) transmission systems, using the decision-directed phase equalizer (DDPE). DDPE updates the equalization parameters on a symbol-by-symbol basis after an initial decision making stage and retrieves an estimation of the phase noise value by extracting and averaging the phase drift of all OFDM sub-channels. Subsequently, a second equalization is performed by using the estimated phase noise value which is followed by a final decision making stage. We numerically compare the performance of DDPE and the CO-OFDM conventional equalizer (CE) for different laser linewidth values after transmission over 2000 km of uncompensated single-mode fiber (SMF) at 40 Gb/s and investigate the effect of fiber nonlinearity and amplified spontaneous emission (ASE) noise on the received signal quality. Furthermore, we analytically analyze the complexity of DDPE versus CE in terms of the number of required complex multiplications per bit.

Techniques for noise and nonlinear impairments compensation in CO-OFDM transmission

“…Blind PNC based on a decision-directed (DD) for CO-OFDM was considered in [10]. However, this technique suffers significantly from error propagation, and thus, it cannot be applied in the presence of a large laser phase noise.…”

Blind Phase Noise Estimation for CO-OFDM Transmissions

“…However, it is still desirable to remove completely the overhead due to pilot subcarriers to maximize the system's SE and power consumption. Blind phase noise estimation for CO-OFDM with a small number of subcarriers (up to 200) has attracted a lot of attention recently [8][9][10]. In [8], a blind phase noise estimation (PNE) method based on a decision-directed (DD) algorithm has been considered for CO-OFDM.…”

“…Blind phase noise estimation for CO-OFDM with a small number of subcarriers (up to 200) has attracted a lot of attention recently [8][9][10]. In [8], a blind phase noise estimation (PNE) method based on a decision-directed (DD) algorithm has been considered for CO-OFDM. A major advantage of DD-based PNE scheme is that it is compatible with any modulation format.…”

A Feedforward Partial Phase Noise Mitigation in the Time-Domain using Cyclic Prefix for CO-OFDM Systems

“…As mitigation of ICI requires sophisticated methods that incur considerable (indeed, prohibitive) computational expense [4], practical phase compensation studies have mainly considered only CPE mitigation based on either DD methods or high-order-statistics (HOS) blind-adaptive algorithms [5,6].…”