BER Performance of PDM 4-QAM Optical Transmission System Considering the Effects of PMD and GVD Using Exact Probability Density Function

Kazi Abu Taher

doi:10.11648/j.ajop.20180601.13

Abstract

A noble theoretical approach is presented to evaluate the bit error rate (BER) performance of an optical polarization division multiplexed (PDM) 4-multilevel quadrature amplitude modulation (4-QAM) transmission system under the combined influence of polarization mode dispersion (PMD) and group velocity dispersion (GVD) in a single mode fiber (SMF). The analysis is carried out considering a coherent homodyne receiver. The exact probability density function (pdf) fluctuation due to PMD and GVD is evaluated from its moments using a Monte-Carlo simulation technique. Average BER is evaluated by averaging the conditional BER over the pdf of the random phase fluctuation. BER performance results are evaluated for different system parameters. It is found that PDM 4-QAM coherent homodyne system doubles the data rate but suffers more power penalty than the 4-QAM system. Results show that for a BER of 10<sup>-9</sup> at DGD of 0.5T and GVD value of 1700 ps/nm the PDM 4-QAM system needs 2.21 dB more power than 4-QAM systems giving the leverage of doubling the data rate.

Highlights

Ever increasing data rates, temperature changes, power variations and changes in stresses induce birefringence causing group velocity dispersion (GVD) and polarization mode dispersion (PMD) values of the optical fiber to the levels that exceed the system tolerances [1,2]
Following the analytical approach developed above, we evaluate the bit error rate (BER) from the conditional BER, considering the phase fluctuation due to only GVD or PMD in 4-multilevel quadrature amplitude modulation (4-QAM) and polarization division multiplexed (PDM) 4-QAM systems
Results are evaluated for a 40 Gbps optical 4-QAM and 80 Gbps PDM 4-QAM homodyne coherent systems with several values of system parameters

Summary

Introduction

Temperature changes, power variations and changes in stresses induce birefringence causing GVD and PMD values of the optical fiber to the levels that exceed the system tolerances [1,2]. The impacts of PMD and GVD in SMF are of great interests in current and generation high speed optical data transmission systems [3, 4]. A noble analytical approach is presented to evaluate the exact pdf of the phase fluctuation due to combined effect of PMD and GVD which is used to evaluate the system BER.

System Model

Theoretical Analysis

Results and Discussion

Conclusion