Sub-THz Wireless Over Fiber for Frequency Band 220-280 GHz

Higher capacity wireless access networks are required to serve the growing demands for mobile traffic and multimedia services. The use of sub-THz carrier frequencies is a potential solution for the increased data demands. This paper proposes and demonstrates experimentally the photonic generation of a multi-band signal for sub-THz wireless-over-fiber transmission at up to 100 Gbit/s (20 Gbit/s in each band) using the full spectrum 220280 GHz for downlink wireless transmission and an uplink with 10 Gbit/s on-off keying. By using an optical frequency comb generator (OFCG), five 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 with Nyquist bandwidth achieved by using root raised cosine filtering with 0.01 roll off factor. These optical subcarriers are combined and transmitted over 10 km of fiber 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 intermediate frequency and digital signal processing (DSP) is employed at the receiver to measure the bit error ratio (BER). The performance is also evaluated to investigate the impact of the uplink on the downlink optical transmission. The receiver link budget and wireless distance for acceptable BER are also explored. The proposed system aims to distribute sub-band THz signals for short range indoor mobile units. The overall transmission capacity is increased by transmitting it as a multiband, which also reduces the bandwidth requirements on opto-electronicdevices.