Maximum-Likelihood Sequence Estimation (MLSE) Equalizer

Compatibility:

This project MLSE Application.osd demonstrates the application of the component ‘MLSE Equalizer’. The MLSE Equalizer component is available in the OptiSystem component library folder ‘Default/Receivers Library/Regenerators’ (Figure 1).

Optical System - Figure 1 OptiSystem component library

Figure 1: OptiSystem component library

The system layout is presented in Figure 2. A 10 GB/s BPSK signal is generated by the ‘BPSK Generator’ component. The signal is then applied to a propagation channel. The propagation channel is an FIR filter with coefficients [1 0.8 0.3], that simulates a time dispersive channel that causes intersymbol interference (ISI). The signal is then applied to the MLSE equalizer component that will compensate the signal dispersion.
The channel estimation is done in the MLSE equalizer using the same coefficients as the FIR filter. The coefficients are loaded from a text file (FIR.dat -Figure 3).

Optical System - Figure 2 System layout

Figure 2: System layout

Optical System - Figure 3 Filter coefficients

Figure 3: Filter coefficients

The MLSE equalizer can also use an optional preamble. Figure 4 presents the eye diagram before and after the equalizer. Figure 5 presents the signal evolution from the channel input to the equalizer output. The equalizer mitigates ISI and improves the system’s performance.

Optical System - Figure 4 Eye diagram before and after the equalizer

Figure 4: Eye diagram before and after the equalizer

Optical System- Figure 5 Signal propagation in the system

Figure 5: Signal propagation in the system