RSoft Design Group has released OptSim 5.0, which is the latest version of its optical communication system design tool. The release will include new advanced features to model next-generation optical networks, with a particular focus on maximum likelihood sequence estimation (MLSE) decoding, electronic dispersion compensation (EDC) equalisation, bi-directional transmission, and advanced modulation formats such as D(Q)PSK and OFDM.
OptSim 5.0 includes a new advanced model implementing an efficient MLSE processor to be used in intensity-modulation direct-detection (IMDD) optical receivers. The block consists of an analogue-to-digital (A/D) converter (ADC) whose samples are sent to a parallel bank of branch metric computation stages. The extracted metric is sent to a Viterbi processor, which uses a reduced-state algorithm. The resolution of the A/D converter (ADC), the number of branch metric stages, and the number of states are user-defined parameters. OptSim’s unique capability of error counting over arbitrarily long bit sequences is the key enabler of MLSE system simulation, since there is no alternative analytical solution to assess the system performance.
In addition to MLSE decoding, OptSim 5.0 includes advanced models for FFE/DFE electronic dispersion compensation with coefficient optimisation based on MMSE criterion. With these models, the user can specify the number of feed-forward and feedback taps. For feedback taps equal to zero, the model degenerates in a FFE EDC. The coefficients can be manually inserted so that the user can perturb their optimal value to study the system resilience to sub-optimal EDC.
OptSim 5.0 also includes additional Monte-Carlo and semi-analytical techniques specific for D(Q)PSK systems, new modulator and demodulator for OFDM systems, and a bi-directional fibre model taking into account co- and counter- propagation of signal and pumps in nonlinear optical fibre.