Analytical estimation of phase noise influence in coherent transmission system with digital dispersion equalization

Analytical BER performance in differential n-PSK coherent transmission system influenced by equalization enhanced phase noise

“…arises from the LO laser phase noise rather than the Tx phase noise, which is consistent with the reported analysis [18][19][20][21][22]. We can also find that the limits of the BER achieve a very good agreement with the BER floors (the dash curve) presented in our previous work [25,29]. Figure 4 shows the BER performance in the 1000 km 28-Gbaud D8PSK transmission system with different distribution of the Tx and the LO lasers linewidths.…”

“…It has been verified that the behavior of the feedback carrier phase estimation using the one-tap normalized least-mean-square (NLMS) algorithm resembles the differential phase estimation [5,10,25]. Therefore, the theoretical BER evaluation based on this model is also suitable for the one-tap NLMS carrier phase estimation.…”

“…Among these methods, the digital coherence enhancement shows the best performance [26,36], while it requires a complicated hardware implementation to measure the LO laser phase fluctuation. By contrast, EEPN does not exist in the coherent transmission systems using optical dispersion compensation, such as dispersion compensating fibers (DCFs) and dispersion compensating modules (DCMs) [18,19,22,25,37,38]. However, the management and the compensation of the fiber nonlinearities in such systems should be seriously considered.…”

“…Considering the impact of equalization enhanced phase noise, the variance of the total noise in the n-PSK coherent transmission system can be expressed as [25,29], 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 when the transmission fiber length is larger than 80 km [25].…”

“…I. Fatadin et al have also studied the influence of the EEPN in quadrature phase shift keying (QPSK), 16-level quadrature amplitude modulation (16-QAM) and 64-QAM coherent transmission systems [24]. Meanwhile, the influence of EEPN on different CPE algorithms has also been investigated in detail by using numerical simulations [25][26][27][28][29]. Due to the EEPN, the requirement of laser 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 linewidth can not be generally relaxed for the transmission system with a higher symbol rate.…”