Performance Investigation of NRZ-DQPSK, CSRZ-DQPSK and MDRZ-DQPSK Modulation Techniques for 450 Channel UD-WDM System for Long Haul Communication

In this paper, we have designed a 450-channel Ultra Dense-Wavelength Division Multiplexing (UD-WDM) system with a bit rate of 100 Gb/s per channel and channel spacing of 0.1 nm based on three spectral efficient advanced modulation techniques named Non-Return-To-Zero Differential Quadrature Phase Shift Keying (NRZ-DQPSK), Carrier Suppressed Return-To-Zero Differential Quadrature Phase Shift Keying (CSRZ-DQPSK), and Modified Duobinary Return-To-Zero Differential Quadrature Phase Shift Keying (MDRZ-DQPSK). The performances of all three modulation techniques mentioned above are investigated using various investigation parameters. We have also demonstrated the experimental setup for measuring attenuation and dispersion under the effect of various linear and nonlinear impairments. Along with the experimental setup, the simulation is performed using optisystem software and the simulation results indicated that the MDRZ-DQPSK modulation technique outperformed the other two modulation techniques. The maximum Quality-Factor (Q-factor) value of 11.3 dB and minimum Bit Error Rate (BER) value of 10−11, minimum eye closure value of 1.44 dB, and minimum probability of error of 0.36 have been reported for MDRZ-DQPSK modulated system when varying distance has been taken into consideration. The maximum receiver sensitivity of −16 dBm, minimum received crosstalk value of −8.8 dB and maximum Q-factor value of 12.6 dB have been reported with varying numbers of channels. The maximum Q-factor of 13.6 dB, minimum BER value of 10⁻¹³, and maximum output power of −38 dBm have been reported with varying input powers. The utilization of a large number of channels in this study enables unprecedented increases in data transmission speeds that were previously unattainable.