Dual-ring 16-Star QAM direct and coherent detection in 100 Gb/s optically amplified fiber transmission: simulation

Abstract

This paper presents the transmission performances, by simulation, of optical communication systems over 10 spans of dispersion compensated and optically amplified fiber distance with a bit rate of 100 Gb/s, by employing modulation formats of two amplitude levels and 8 phase states per amplitude level, the 2R-16-Star QAM constellation under direct and coherent detection with and without phase estimation. Different ring ratios of the amplitude levels are examined and associate transmission performances are reported. Optical signal to noise ratio is achieved with 18 dB and 23 dB for back to back and long haul transmission cases with a dispersion tolerance of ±67 ps/nm at 2 dB power penalty of the eye opening at 100 Gb/s. Monte-Carlo simulation is also performed and a receiver sensitivity of −15 dBm is achieved for a BER of 10 −5 under direct detection after 1100 km of dispersioncompensated and optically amplified transmission. Transmission performances, bit error rate versus receiver sensitivity, are also confirmed with the use of the eye diagram and associate multiple-peaks statistical spectral density distribution. For 100 Gb/s 2R-16-Star QAM coherent transmission, an improvement of the receiver sensitivity of 2.5 dB and 3.5 dB is obtained for coherent detection without phase estimation and respectively. Under coherent detection with phase estimation, the chromatic dispersion tolerance reaches ±100 ps/nm for a 2 dB eye opening penalty at 100 Gb/s bit rate. Comparative studies of the transmission performances of the Star and Square QAM modulation formats are also conducted under the fiber linear and nonlinear effects and detection with and without phase estimation.

Error Analysis of 2-tierM-ary Star QAM Modulation in Shadowed Fading Channels

“…from Figure 1 we equate the distance between s 0 and s 1 and s 0 and s 8 . The relation can be easily computed using geometric methods as given in [27] for 16-ary Star QAM. Generalizing the expression the optimum ring ratio in AWGN is given by,…”

Phase-preserving multilevel amplitude regeneration using modified nonlinear amplifying loop mirrors

“…Since phase-preserving amplitude regeneration is considered to be necessary for reduction of amplitude fluctuations as the origin of nonlinear phase noise, a total nonlinear phase shift of 200 rad/W was included in the nonlinear transmission span after the regenerator. The BER was calculated using optimized threshold levels between the constellation points of the star-8QAM signal using a non-coherent balanced DQPSK receiver with additional signal power detection 5 . Because of different optimal operation points of the NALM for both schemes, different state amplitude ratios for the star-8QAM format were used: for a single NALM the power ratio of the two amplitude levels was chosen to be 1:3 while a ratio of 1:7 was used for the cascade.…”