Page 69 - Kaleidoscope Academic Conference Proceedings 2021

Connecting physical and virtual worlds

As a research subject for virtualized terminals, it is necessary [4] The Ministry of Internal Affairs and
to clarify the terahertz wave propagation characteristics Communications, “Beyond 5G Promoting Strategy”,
including the effects of reflection and scattering by the https://www.soumu.go.jp/main_sosiki/joho_tsusin/e
human body. It is difficult to ensure the quality of wireless ng/presentation/pdf/200414_B5G_ENG_v01.pdf .
communications unless the terahertz band is line-of-sight, so
it is necessary to have a technical means of detecting [5] KDDI Corporation and KDDI Research Inc.,
peripheral devices that can attain each wireless “Beyond 5G/6G White Paper ver.1.0.1”,
communication quality and assign them appropriately. This https://www.kddi-
technology will have to adapt dynamically according to user research.jp/english/tech/whitepaper_b5g_6g/ .
behavior and environmental changes. In addition, for
terahertz links, due to the realization of terahertz RF-front- [6] J. Zhang, S. Chen, Y. Lin, J. Zheng, B. Ai, and L.
end performance and the increase in the distance between the Hanzo, "Cell-free massive MIMO: A new next-
main user terminal and peripheral devices, functions such as generation paradigm", in IEEE Access, Vol.7, pp.
simple antenna beam forming and tracking to peripheral 99878-99888, 2019, doi:
devices are required. Furthermore, since analog frequency 10.1109/ACCESS.2019.2930208.
conversion from the terahertz band to access-link band is
performed and transmitted, a wave-form suitable for both [7] E. Björnson and L. Sanguinetti, “Making cell-free
frequency bands and signal processing technology that massive MIMO competitive with MMSE processing
equalizes the propagation characteristics of both frequency and centralized implementation”, IEEE Trans.
bands are required to realize CF-mMIMO. Wireless Commun., Vol.19, No.1, pp.77–90, Jan.
2020.
4. CONCLUSIONS AND FUTURE WORK
[8] H.Q. Ngo, A. Ashikhmin, H. Yang, E.G. Larsson,
In this paper, we proposed a new RAN architecture called and T.L. Marzetta, “Cell-free massive MIMO versus
"User-centric RAN Architecture" towards Beyond 5G. In the small cells”, IEEE Trans. Wireless Commun.,
user-centric RAN architecture, connectivity to the network Vol.16, No.3, pp.1834–1850, March 2017.
with sufficient quality must always be provided to users who
demand that various quality requirements be satisfied [9] T. Choi et al., “Co-located vs distributed vs semi-
anytime, anywhere in the physical space. In order to achieve distributed MIMO: measurement-based evaluation”,
this, it is necessary to eliminate the degradation of radio Proc. of Asilomar Conf. Signals Syst. Comput., Nov.
quality at the cell edge, which requires the installation of a 2020.
much larger number of base stations in higher density.
Furthermore, in order to overcome the imbalance in [10] M. Ito et al., “On Spectral and Energy Efficiency of
communication quality between the uplink and downlink Semi-Distributed Cell-Free Massive MIMO”, 2021
still found in 5G, it is also necessary to expand the limits on IEICE general conference, B-5-19, 2021.
the number of antennas of user terminals and the power
consumption of user terminals. On the other hand, it is also [11] T. Murakami et al., “Research Project to Realize
important to realize technology for developing a virtualized Various High-reliability Communications in
RAN in order to build the RAN that corresponds to the user's Advanced 5G Network”, 2020 IEEE Wireless
situation in real space. Future work includes R&D on Communications and Networking Conference
elemental technologies, control technologies, devices, and (WCNC), 2020, pp. 1-8.
antenna technologies, etc., to solve many of the issues
described in Section 4. [12] O-RAN Alliance, https://www.o-ran.org/ .

REFERENCES [13] A. Faisal, H. Sarieddeen, H. Dahrouj, T.Y. Al-
Naffouri, and M.-S. Alouini, “Ultramassive MIMO
[1] ITU-T Focus Group on Technologies for Network systems at terahertz bands: Prospects and
2030 https://www.itu.int/en/ITU- challenges”, IEEE Veh. Technol. Mag., Vol.15,
T/focusgroups/net2030/Pages/default.aspx. No.4, pp.33–42, Dec. 2020.

[2] ITU-T FG-NET-2030, "Network 2030 A Blueprint [14] T. Kawanishi, K. Inaga, A. Kanno, N. Yamamoto, T.
of Technology, Applications and Market Drivers Aiba, H. Yasuda, and T. Wakabayashi, “Terahertz
Towards the Year 2030 and Beyond", and Photonics Seamless Short-Distance Links for
https://www.itu.int/en/ITU- Future Mobile Networks”, Earth and Space Science
/focusgroups/net2030/Documents/White_Paper.pdf. Open Archive, doi: 10.1002/essoar.10503612.1.

[3] Japan Cabinet, “Society 5.0”,
https://www8.cao.go.jp/cstp/english/society5_0/inde
x.html.

– 7 –