Multiband transmission for sub-THz wireless over fibre communication system

In this paper, we propose and experimentally demonstrate the photonic generation of a multiband signal for sub-THz wireless-over-fibre at up to 100 Gb/s (20 Gb/s in each band) using the full spectrum 220-280 GHz for downlink wireless transmission and an uplink with 10 Gb/s on-off keying (OOK). By using an optical frequency comb generator (OFCG), 5 optical tones spaced by 15 GHz are selected and split into odd and even optical subcarriers modulated separately using 10 Gbaud quadrature phase shift keying (QPSK) with Nyquist bandwidth achieved by using root raised cosine (RRC) filter with 0.01 roll off factor. These optical subcarriers are combined and transmitted over 10 km fibre to the remote antenna unit (RAU). The optical bands are then filtered and transmitted separately at the RAU in a wireless channel. The received sub-THz band is down-converted to the IF frequency and digital signal processing is employed at the receiver to measure the BER. The performance is also evaluated to investigate the impact of the uplink on the downlink optical transmission.