26.8-m THz wireless transmission of probabilistic shaping 16-QAM-OFDM signals

Abstract

Recently, remarkable efforts have been made in developing wireless communication systems at ultrahigh data rates, with radio frequency (RF) carriers in the millimeter wave (30–300 GHz) and/or in the terahertz (THz, >300 GHz) bands. Converged technologies combining both the electronics and the photonics show great potential to provide feasible solutions with superior performance compared to conventional RF technologies. However, technical challenges remain to be overcome in order to support high data rates with considerably feasible wireless distances for practical applications, particularly in the THz region. In this work, we present an experimental demonstration of a single-channel THz radio-over-fiber (RoF) system operating at 350 GHz, achieving beyond 100 Gbit/s data rate over a 10-km fiber plus a >20-m wireless link, without using any THz amplifiers. This achievement is enabled by using an orthogonal frequency division multiplexing signal with a probabilistic-shaped 16-ary quadrature amplitude modulation format, a pair of highly directive Cassegrain antennas, and advanced digital signal processing techniques. This work pushes the THz RoF technology one step closer to ultrahigh-speed indoor wireless applications and serves as an essential segment of the converged fiber-wireless access networks in the beyond 5G era.

Terahertz band: Lighting up next-generation wireless communications

“…Most recently, a record data rate of up to 600 Gbit/s is experimentally demonstrated by multiplexing antennas and benefiting from advanced DSP algorithms [108]. In addition, we also report a 26.8 m wireless transmission link with data rates of 119.1 Gbit/s featuring both high speed and long distance in 2020 [109]. This representative THz-over-Fiber system is shown as follows.…”

“…Afterwards, the THz signals from photodiode are radiated into the free space towards the receiver via a pair of high gain antennas. At the receiver, the LO signal mixed with the THz signal to generate an IF signal by using a Schottky subharmonic electronic mixer, which is finally sampled by an oscilloscope [109].…”

Terahertz direct modulation techniques for high-speed communication systems

“…In 2020, Shiwei Wang et al reported a communication system that could support 10 km optical fiber transmission and 26.8 m terahertz transmission at a rate of 119.1 Gbps [15]. The system applied 16QAM modulation.…”

“…In addition to different system architectures, the de- [15], and (c) is the system architecture and received constellation of [16].…”

16-QAM Vector Terahertz-Wave Signal Generation by Simple MZM-Based Optical Frequency Comb

“…Now employing optical heterodyne beating of two independent free running lasers is the major method to produce photonic vector THz-wave signal, which has huge merits of simplifying transmitter structure design and get radio frequency carrier tuned and frequency assignment easily [18][19][20][21][22][23][24][25][26]. However, the generated continuous light-waves based on two independent running lasers encounter frequency instabilities.…”