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An adaptive compression method in intermediate frequency band digitized radio over fiber is proposed for mobile fronthaul, aiming at reducing the transmission rates. The proposed method uses radio channel state information parameters to control fronthaul compression. The simulation results demonstrate the ability of the proposed method on reducing the quantization error, allowing the use of lower (4-bits) quantizer resolution for 64-QAM modulated signals, providing 2:1 compression rate with near zero EVM. In addition, our proposed method surpasses $\mu $ -law and $A$ -law compression techniques and performs in shorter times than 5G latency target (1 ms). Finally, the performance of uncompressed and compressed signal is assessed experimentally in 20 km of fiber transmission. [ABSTRACT FROM AUTHOR]

We propose a pre-distortion scheme in transmitter DSP to reduce the peak-to-average power ratio (PAPR) in multi-intermediate-frequency (IF)-over-fiber mobile fronthaul (MFH). In optical spectral efficient MFH, multiple modulated sub-bands are transmitted with different IFs serving multi-in multi-out and carrier aggregation in 5G. By applying phase pre-distortion on sub-bands in the transmitter DSP, we reduce the PAPR by more than 2.2 dB with 1% complementary cumulative distribution function value in MFH for 5G mobile networks and significantly increase the transmitted signal power and quality without modifying the system linearity and resolution. The proposed scheme generates small latency. It is DSP efficient and compatible with current mobile devices, without additional noise. With 32 sub-bands served, we demonstrated a 2-dB sensitivity improvement experimentally by applying the proposed scheme. [ABSTRACT FROM PUBLISHER]

A nonlinear pre-distorter (NLPD) at the transmitter, and a maximum-a-posteriori probability (MAP) detector, time-domain Volterra nonlinear equalizer (VNLE), or sparse-VNLE at the receiver are compared for compensation of the pattern-dependent distortion that can occur in high baud rate transmitters and receivers. Experimental results are presented for a 1.206-Tb/s dual-polarization 16-ary quadrature-amplitude-modulation (16-QAM) superchannel signal with three subcarriers. The NLPD with iterative calculation of the pre-distortion provides the best performance in back-to-back systems and transmission systems followed by the MAP detector, VNLE, and sparse-VNLE. At the FEC threshold of 1.9\times 10^-2 , the NLPD provides an increase in the transmission distance of 300 km compared with the sparse-VNLE, VNLE, and MAP detector. For transmission over 1500 km of SMF, the VNLE and MAP detector exhibit additional optical signal-to-noise ratio margins of 0.16 and 0.47 dB relative to the sparse-VNLE. Compared with the VNLE, the sparse-VNLE exhibits a 55% reduction in number of kernel coefficients. [ABSTRACT FROM PUBLISHER]