Fig. 1. Noise transfer function. (a) Zero points and pole points; (b) frequency response of amplitude.

Fig. 2. Principle of NNEs.

Fig. 3. Experimental setup of PDM-8192-QAM W-band wireless delivery over 4.6 km. Photos of (a) Guanghua Building in the Handan campus; (b) transmission link; (c) Physics Building in the Jiangwan campus; (d) transmitter; (e) receiver.

Fig. 4. Offline DSP for transmitter and receiver.

Fig. 5. (a) Electrical spectrum of received 13.5-GHz IF signals; (b) electrical spectrum of baseband signals after NNE.

Fig. 6. Curves of BER versus power into the PD at the case of 10 Gbaud PDM-QPSK signal. (i) constellation with only DSM; (ii) constellation with DSM and NNE.

Fig. 7. Curves of BER versus power into the PD at the case of 1 Gbaud PDM-OFDM signal. (a) Constellation of 1024-QAM (i) and constellation of 2048-QAM (ii); (b) constellation of 4096-QAM (i) and constellation of 8192-QAM (ii).