Page 64 - Kaleidoscope Academic Conference Proceedings 2021

2021 ITU Kaleidoscope Academic Conference

Accelerate 5.0” and “Beyond5G/6G White paper” [5]. The technologies, Cell-Free massive MIMO (CF-mMIMO),
concept is aimed at speeding up the realization of Society 5.0, RAN management, and a virtualized terminal. Finally,
a sustainable user-centric society where economic Section 4 provides a summary and future perspectives.
development is boosted, and the future society of 2030 is
brought a step closer. 2. USER-CENTRIC RAN ARCHITECTURE

An overview of user-centric RAN architecture is shown in
Figure 2. In our proposed user-centric RAN architecture, a
wireless communication system based on the CF-mMIMO
wireless technology is constructed with Central Processing
Units (CPUs) and Access Points (APs). In addition, we aim
to realize an advanced wireless system that constructs a
desirable wireless environment for each user’s location
through user-centric RAN management that controls radio
and computer resources in a very flexible manner. We will
also introduce the concept of virtualized terminals to expand
the capabilities of the user terminals themselves.

To eliminate the degradation of communication quality
especially at cell edge locations, a transmission and reception
Figure 1 – Seven technologies for accelerating Society 5.0 scheme called the Coordinated Multipoint transmission /
reception (CoMP) has already been proposed. In this scheme,
Figure 1 shows the seven technologies required for multiple different cells coordinate their scheduling and link
accelerating Society 5.0. The “1 Network” will provide data adaptation to provide simultaneous communication to a
flows between the “physical space” and “cyber space” single user terminal. However, this scheme is based on
shown as two arrows in Figure 1. Real people and objects conventional cell deployment in which areas composed of
exist in the physical space, and a computer world is individual cells are connected to each other in a planar
integrated into the cyber space. The information collected manner, and it cannot flexibly meet the situation and
from the physical space is analyzed in cyber space and fed communication requirements of user terminals.
back to the physical space.
In contrast, we believe CF-mMIMO is a promising approach,
From the above, the Beyond 5G mobile communication in which the optimal combination of base stations and
network with the CPS should carry huge data traffic between antennas is automatically selected according to the user’s
the physical space and cyber space. This is a similar location, radio coverage, and its communication
requirement in the 5G mobile communication network, but requirements. To realize this architecture, a huge number of
there are two different points: a network will be constructed antennas needs to be deployed in the area, which used to be
by the user’s requirements, and wireless links for user managed by a single CPU. The modulation and
terminals or devices will be provided anytime, anywhere. demodulation of radio signals is handled in a coordinated
We called a Radio Access Network (RAN) to satisfy those manner between the antennas and the CPU to create an
points “user-centric RAN”, and its architecture, a “user- optimal wireless environment at the user's location. Here, in
centric RAN architecture”. The current mobile order to deploy a large number of antennas at a low cost, a
communication network adopts a cellular architecture in user-driven method of deploying antennas can be considered.
which the radio coverage is determined by the location of However, such a method cannot guarantee the required
base stations. In this case, the communication quality is quality of communication, and will result in areas where the
greatly affected by the distance from the base station and the same situation as that at the cell edge occurs. Therefore, we
user's location, and it is not possible to provide high radio assume here a system in which many antennas are deployed
quality everywhere. Additionally, 5G mobile terminals have reliably by the operator. To reduce the network construction
severe limitations in terms of size and power compared to cost, it is desirable to consolidate the distributed antennas in
base stations, which limits the number of antennas and the same location. On the other hand, if multiple antennas are
transmission power that can be installed, and the quality of concentrated in the same location, the spectrum efficiency
the uplink is greatly degraded compared to the downlink. We may decrease because the spatial correlation between
aim to realize a user-centric RAN architecture that provides antennas may be degraded and the interference may not be
stable communication quality surrounding the user by eliminated. This trade-off relationship should be solved to
eliminating the degradation of communication quality and construct a user-centric architecture effectively.
imbalance between uplink and downlink capacity.
The user-centric RAN will provide the communication
In this paper, we present our approach of the user-centric quality required by the user anytime and anywhere. To
RAN architecture toward Beyond 5G and key technologies realize a nationwide mobile network with the user-centric
to realize the user-centric RAN. Section 2 describes the RAN architecture, an ultra-flexible RAN management is
architecture overview. In Section 3, we present the three key required. One of the RAN management types is a placement

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