Transceiver Impairment Mitigation by 8×2 Widely Linear MIMO Equalizer With Independent Complex Filtering on IQ Signals

Abstract

High-order modulation formats with high symbol rates are promising candidates for meeting the growing traffic requirements of digital coherent transmission. In using these modulation formats, the impact of transceiver impairment on the signal quality becomes significant. In this paper, we propose an 8×2 widely linear (WL) multiple-input multiple-output (MIMO) equalizer with independent complex filtering on IQ signals to mitigate linear transceiver impairments. Furthermore, we extend the equalizer for digital subcarrier (SC) multiplexing. Accordingly, a 16×4 WL MIMO equalizer is also proposed to mitigate linear transceiver impairments, through application to a pair of SC inputs. Experimental results show that, for transmission of a 58-GBaud polarization-multiplexing 64 quadrature amplitude modulation (PM-64QAM) single-carrier signal, the proposed method effectively compensates for various receiver impairments and also mitigates transmitter (Tx) impairments. Q-penalties of 0.1 dB up to a 10-ps skew, 2.5-dB gain imbalance, 7.2-degree phase error, and -15-dB crosstalk in Tx were achieved for 100-km standard single-mode fiber transmission. Moreover, for a 29-GBaud PM-64QAM dual-SC signal, the proposed 16×4 WL MIMO equalizer shows transceiver impairment mitigation performance similar to that in the singlecarrier case, even though dual-SC transmission is less tolerant of laser phase noise.

Device-compatible ultra-high-order quantum noise stream cipher based on delta-sigma modulator and optical chaos

“…After that, an 8 × 2 widely-linear multiple-input and multiple-output (WL-MIMO) algorithm is introduced to implement the channel equalization, polarization demultiplexing, and the transmitter impairment post-compensation. The tap coefficient is 63, the step size is 1.2 × 10 −5 , the step size of phase is 64 and the overhead 5000 16QAM symbols are for pre-convergence of the MIMO equalizer 31 . Then, the error symbol is corrected by FEC.…”

Experimental Comparison of Single-Carrier and Digital Subcarrier Multiplexing Transmissions in a W-Band 200 Gb/s Fiber-Wireless System Considering Transmitter IQ Imbalance and Skew Mitigation

“…In fact, (11) indicates that the signals coming from the symmetric SC at angular frequency w n have to be jointly processed with the components of the SC at angular frequency −w n to completely eliminate interference. In addition, we find that (11) is a linear transformation which means that IQ mixing effects can be fully compensated by the 4 × 4 real-valued MIMO equalizer.…”

“…Meanwhile, a higher symbol rate with higher-order modulation format is more susceptible to the in-phase (I) and quadrature (Q) imperfections in the transceiver caused by component defects or misalignments, such as gain imbalance, phase imbalance, and skew, which are referred to IQ mixing effects, could lead to significant degradation of system performance This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ [10], [11]. In order to fairly compare the nonlinear tolerance of SC and SCM signals in the large capacity fiber-wireless integration system, the mitigation of linear impairments such as IQ mixing effects becomes especially important.…”

Wideband Multichannel Nyquist-Spaced Long-Haul Optical Transmission Influenced by Enhanced Equalization Phase Noise

“…Nevertheless, distortions generated by interactions between LPNs and fiber dispersion, i.e., enhanced equalization phase noises (EEPNs), are difficult to effectively compensate at present [ 1 , 3 ]. The EEPN effects have attracted increasing research attention from academic and industrial institutions in recent years [ 4 , 5 , 6 , 7 , 8 , 9 ]. The perturbation-based Guassian noise (GN) model is a convenient and sufficiently accurate method to predict the quality of signal transmission over long-haul fiber systems [ 10 , 11 , 12 ].…”