Abstract
We propose an indoor network with a sub-terahertz- band wireless link for 6G applications. In our proposed indoor network, an optical hub unit (OHU) that controls the entire system is optically linked to THz remote nodes (RNs) over optical distribution fibers. The THz RNs communicate with the user equipment through a sub-THz wireless link. The function of the THz RNs is to provide an interface between the optical link and the sub-THz wireless link. For downlink transmission, a photonics-based sub-THz-band signal generation method is adopted to take advantage of the broadband characteristics of the optical components. An electronics-based sub-THz mixer is also used for uplink transmission because of its cost-effectiveness and low energy consumption. A digital signal processor (DSP) is designed to recover the original transmitted baseband signal. The DSP provides frequency offset compensation over a wide frequency range and reduces the probability of cyclic slip. The performance of the proposed system was investigated experimentally with commercially available optical/electrical components. We demonstrate 100 Gb/s 2.5-m wireless transmission with a 16-quadrature amplitude modulation (16-QAM) signal for configuring the downlink. The optical transmission distance was set to 10 km, and the power penalty measured by optical transmission was negligible. We also investigated the scalability and tunability of the photonics-based sub-THz transmitter to confirm the upgradability of our proposed indoor network to consider future capacity expansion. To establish an uplink, a 25 Gb/s 1.5-m wireless transmission with a quadrature phase shift keying (QPSK) signal was employed. A directly modulated laser was used for cost-effective optical transmission. Unlike downstream transmission, a measured bit error rate (BER) penalty caused by the optical transmission was observed. This is due to the interplay between the frequency chirp of the directly modulated laser and the chromatic dispersion in the fiber. Despite this penalty, BERs less than the soft-decision forward error correction (FEC) threshold (2 × 10<sup>−2</sup>) with 20% overhead were achieved. We discuss several remaining technical challenges in real-field deployment. These include THz Tx power improvement, photonic integration, reducing form-factor, polarization insensitivity, and automatic beam steering. Our recent efforts to address these issues are also introduced and examined.
Highlights
R ECENTLY, a few key innovations that are likely to impact our lives in a major way have been proposed
It is based on the conventional architecture of distributed antenna system (DAS) with radio-over-fiber technology (RoF) which have been widely investigated for 5G network [13,14,15]
We proposed an indoor network with sub-THzband communication technology for 6G applications
Summary
R ECENTLY, a few key innovations that are likely to impact our lives in a major way have been proposed. We propose an indoor network with sub-THz-band communication technology It is based on the conventional architecture of distributed antenna system (DAS) with radio-over-fiber technology (RoF) which have been widely investigated for 5G network [13,14,15]. The user equipment generates a sub-THz-band signal using an electronics-based mixer, which is transmitted to the THz RN. The sub-THzband signal is down-converted to the intermediate frequency (IF) band using an electronics-based mixer In this setup, an arbitrary waveform generator (AWG, Keysight M8194A), which has a maximum sampling rate of 120 GSa/s and an analog bandwidth of 45 GHz, was used to generate a singlecarrier 16-QAM baseband signal. The length of the bit sequence was ~1.4 × 105 bits, excluding training bits
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
