Maximum-likelihood sequence detection with closed-form metrics in OOK optical systems impaired by GVD and PMD

Abstract

Abstract-This paper thoroughly investigates the maximumlikelihood sequence detection (MLSD) receiver for the optical ON-OFF keying (OOK) channel in the presence of both polarization mode dispersion and group velocity dispersion (GVD). A reliable method is provided for computing the relevant performance for any possible value of the system parameters, with no constraint on the sampling rate. With one sample per bit time, a practically exact expression of the statistics of the received samples is found, and therefore the performance of a synchronous MLSD receiver is evaluated and compared with that of other electronic techniques such as combined feedforward and decision-feedback equalizers (FFE and DFE). It is also shown that the ultimate performance of electronic processing can be obtained by sampling the received signal at twice the bit rate. An approximate accurate closed-form expression of the receiver metrics is also identified, allowing for the implementation of a practically optimal MLSD receiver.Index Terms-Chromatic dispersion, electrical equalization, intersymbol interference (ISI), maximum-likelihood sequence detection (MLSD), optical transmission systems, polarization mode dispersion (PMD).

Advanced Modulation Formats and MLSE Based Digital Signal Processing for 100Gbit/sec Communication Through Optical Fibers

“…Maximum likelihood sequence detection is the proven to be the most effective technique for mitigating optical channel impairments such as chromatic dispersion and polarization mode dispersion (Foggi et al, 2006). In order to successfully apply this technique, it is mandatory to estimate some key channel parameters needed by the Viterbi processor.…”

“…It is clear that in (3.2) 0 N and  need to be estimated. More information about parametric estimation is given in (Agazzi et al, 2005;Foggi et al, 2006).…”

Robust Multilevel Coherent Optical Systems With Linear Processing at the Receiver

“…The excellent agreement deserves no further comment. It can be observed that, provided the value of is sufficiently large, the performance of the b2b 12 As shown in [38], the ratio E =N represents the number of detected photons per bit at the input of the optical amplifier and is related to the optical signal-to-noise ratio (OSNR) by E =N = 22 OSNR 2 WT, with W being the reference measurement bandwidth usually taken equal to 12.5 GHz (0.1 nm). case, also shown for comparison, can be attained.…”

Channel Estimation Algorithms for MLSD in Optical Communication Systems

“…Since a square-law detector is used at the receive end, postdetection noise statistics change [1], [10], [11], and can no longer be considered Gaussian. A suitable closed-form expression of the branch metrics of the Viterbi algorithm (VA) implementing the MLSD strategy is provided in [7] and [8]. However, some parameters of the distribution of the received samples depend not only on the transmitted pulse shape, filter types, and bandwidths, but also on the channel impairments and on the noise power spectral density (PSD) [8].…”

“…A suitable closed-form expression of the branch metrics of the Viterbi algorithm (VA) implementing the MLSD strategy is provided in [7] and [8]. However, some parameters of the distribution of the received samples depend not only on the transmitted pulse shape, filter types, and bandwidths, but also on the channel impairments and on the noise power spectral density (PSD) [8]. Due to the square-law nature of a photodiode, the estimation of the required channel parameters is not straightforward.…”