Abstract-Terahertz and Photonics Seamless Networks

Tetsuya Kawanishi

https://ieeexplore.ieee.org/document/9024641

Radio links using terahertz (THz) waves can provide high-speed wireless transmission whose bitrate is higher than 100Gb/s. Congestion of radio spectrum in THz bands (0.1-10 THz) is not so significant for the time being. However, multi- level modulation formats would be required in in THz bands as well as in conventional millimeter- wave or microwave bands, to increase spectral efficiency. We provide overviews on spectral efficiency and transmission capacity of high-speed radio links using THz bands. Reduction power consumption in radio equipment is also very important to reduce operation cost of networks. We describe a survey result on power consumption of short-distance wireless systems. The result implies that THz high-speed radio links would be useful to reduce power consumption per bit in transmission. However, transmission distances in THz systems would be shorter than a few kilometers due to attenuation in the air. Thus, we should rely on seamless networks consisting of THz radio- links and optical fibers, where devices developed for optical fiber transmission can be used to THz wave generation and detection.

Published in: 2019 IEEE Globecom Workshops (GC Wkshps)

Abstract-THz and Photonic Seamless Communications

Tetsuya Kawanishi

https://ieeexplore.ieee.org/document/8632660

Terahertz (THz) wave can offer over 100-Gb/s wireless transmission by the use of wide spectrum. Due to features of high-frequency waves such as lightwaves, THz can have high directivity. To mitigate congestion of radio spectrum, advanced modulation formats will play significant roles in THz bands as well as in conventional millimeter-wave or microwave bands. This paper will provide overviews on spectral efficiency and transmission capacity of THz wave systems. Power consumption of radio links would be also an important issue to reduce OPEX of networks. Survey on power consumption of short-distance wireless systems implies that high-speed radio transmission using THz bands would provide low power consumption transmission. However, THz transmission distance will be limited in shorter than a few kilometers due to attenuation in the air. Seamless networks consisting of THz links and optical fibers would provide high-speed, low-latency, and low power consumption data transmission. Devices and signal processing functions developed for optical fiber transmission can be applied to high-speed THz communications.

Abstract-Millimeter- and terahertz-wave radio-over-fiber for 5G and beyond

Pham Tien Dat,  Atsushi Kanno,  Toshimasa Umezawa,  Naokatsu Yamamoto,  Tetsuya Kawanish

http://ieeexplore.ieee.org/document/8012702/

This paper reviews our recent research activities on seamless fiber-wireless systems for future mobile networks, including: radio-on-radio-over-fiber; signal processing-aided multiple signal transmission; high-capacity seamless system; and simultaneous power- and radio-over-fiber.

Abstract-Seamless Fiber-Wireless Bridge in the Millimeter- and Terahertz-Wave Bands

Atsushi Kanno, Pham Tien Dat, Norihiko Sekine, Iwao Hosako, Naokatsu Yamamoto, Yuki Yoshida, Ken-Ichi Kitayama, and Tetsuya Kawanishi

https://www.osapublishing.org/jlt/ViewMedia.cfm?uri=jlt-34-20-4794&seq=0

Fiber-wireless transmission in the terahertz-wave band as well as in the millimeter-wave band is the key for a seamless integration of radio and optical networks in a physical layer. Advanced optical fiber communication technology enables a high precision direct waveform transfer between optical and radio domains. For realization of a seamless conversion, an optical-terahertz converter is configured with optical heterodyning for an optical-to-terahertz conversion. Analog optical modulation techniques by an input millimeter-wave signal and an intermediate frequency component after a frequency downconversion are utilized for a terahertz-to-optical conversion. A quadrature phase-shift keying signal transmission in an optical-fiber-to-radio-to-optical-fiber link (fiber-wireless bridge) is successfully demonstrated with the 90 and 300-GHz signals, simultaneously, using an optical frequency comb source. The possible transmission distance in severe weather conditions in these frequency bands is also discussed.

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