Flexible multiband OFDM ultra-wideband services based on optical frequency combs

In the paper, a flexible multiband orthogonal frequency-division multiplexing (OFDM) ultra-wideband service based on optical frequency combs is proposed and experimentally demonstrated for 5G wireless communications. By using optical frequency comb technology, the flexibility and capacity of wavelength-division multiplexing passive optical networks (WDM-PONs) can be improved. Meanwhile, the different sub-bands of multiband OFDM ultra-wideband signals are modulated with different modulation formats to ensure the data rate needs of different users. An adaptively modulated 128-/64-/32-ary-quadratureamplitude- modulation-encoded multiband OFDM ultrawideband signal is generated. In addition, a joint channel estimation method with training sequences and pilot symbols is applied to improve system performance. After 50-km standard single-mode fiber transmission, the experimental results show that the proposed system can provide bandwidth resources for 15 end users with an average access rate of 1.781 Gb∕s per user and a high data rate of 5.343 Gb∕s.