Intoduction
6G is the next evolution of 5Gnetworks including 5G and 5G-Advanced. One of the major contributions of 6G networks and 6G technology will be the full merging of artificial intelligence AI and Telecom ICT word, as indicated and presented by Prof. Merouane Debbah and Technology Innovation Institute TII at Abu Dhabi AI Summit (ADAIS), targeting into exotic services and applications like holographic video calls and augmented reality (AR) Avatar communications. In order to achieve these goals the key solution will be the immense available channel bandwidth, which can be found ONLY in the THz bands close to light communication frequencies.
Visible Light Communication VLC and the similar LiFi as promoted and explained by Prof. Harald Haas (University of Edinburgh UK) with company pureLiFi, are lately considered by 3GPP and ETSI in 6G standardization as one of the key enablers to this 6G service and performance.
Combining AI, VLC, NOMA non-Orthogonal Multiple Access and MIMO with RIS antennas (highly revealed and explained by prof. Emil Björnson at KTH ) 6G networks will be able to move to high capacity with Tbps throughputs.
Photo Source: Boston University
Review: Future mobile networks. like 6G and further technologies and ahead, will utilize maximum full-capacity spectrum communication, considering strongly the deep integration and complementary benefits of all available frequency bands starting from below 6GHz, the Millimeter Wave mmW, the Terahertz (THz) band as well the Visible Light band. The ultimate target is to obtain the dynamics and the benefits of each frequency band in order to optimize the overall service quality and bandwidth for highly demanding and greedy special services like holographic videos and real time communications using Avatars. In a short term THz and Visible Light bands will provide more capacity and higher speed in local and short-distance scenarios for both indoor as well as outdoor scenarios.
Contribution: Existing nowadays 5G (3GPP Rel.15-16) and 5G-Advanced (3GPP Rel.17-18) as the preliminary advent of 6G, promote services like URLLC and massive Machine Type Communications (mMTC), which have imposed extreme requirements in the network capacity from both throughput as well as number of connected devices.
Of course there is a lot of discussion lately, in the 3GPP standards as well as the vendors R&Ds about improving the existing 5G technologies like massive MIMO (mMIMO) technology with MU-MIMO enhancements, better beamforming techniques with together with OFDMA/CDMA NOMA solutions, network coding, more Component Carrier (CC) aggregation, network densification with heterogeneous networks of overlapping sectors etc.
However all those nice ideas and enhancements cannot contribute more than few percentages on the requested capacity since our major enemy who restricts our network performance will be always the SINR component on the so famous Shannon’s Capacity theorem.
And it is exactly where special purpose technologies like Visible Light Communication (VLC) and the similar LiFi are considered to be the next key-enabler steps, the promising technologies for improving data rate and system capacity in 6G networks. This is because the simpler and easier way to improve system capacity is always to increase the available bandwidth and minimize in the same time SINR. Indeed VLC offers an immense spectrum ranging from 43THz to 790 THz, and this is a rich, huge yet unused spectrum bandwidth. On the other hand visible light can hardly penetrate through walls thus greatly reducing the interference among Light-Emitting Diode (LED) communication cells while keeping enhanced the degree of spatial reuse and the security of sensitive data.
The THz band exploitation: European Telecommunications Standards Institute (ETSI), 3GPP as well as other agencies are currently considering the bands beyond 90 GHz to provide high-data rate wireless services for short (5 to 20 meters) mobile user devices and medium distance (50 to 300 meters) for fixed wireless broadband links. The next quest of these standardization bodies for 6G and beyond is driving, leading and forcing the current research to focus on the effective exploitation of the sub-THz (90- 450 GHz) and visible light bands as potential and tentative solutions to provide wireless optical-fiber like performance for few tens of Tbps.
We have always to keep in mind that 6G will be the first network to include some exotic services as holographic video calls on-the-go as well as avatar augmented reality communications. The never ending quest for higher data rates and the subsequent more spectrum availability is only achieved with the THz spectrum usage. The need to support very high data rates close to some tens of Tbps is mandatory to enable holographic high quality communications, requiring the strong exploitation of THz bands where visible light communication technology offers. Consequently the joint support of higher spectrum and higher network densification sets the target for the future decade of wireless services to provide at least the challenging Tbps aggregated bit rate in small regions.
This 6G wireless optical communications based on VLC or LiFi is one of the most vivid Research Topics bringing together researchers from academia and industry, to explore the development, implementation, and application of Visible Light Communication systems in 6G and Beyond 6G (B6G) networks. Although currently available VLC indoor technology’s throughput is limited in the range of several tenths of Mb/s to 100 Mb/s in the cell distance range of about 5-10 meters, these limitations will disappear with the introduction of upcoming new light sources based on microLED which is expected to soon offer near 10Gb/s on a single diode LED chip-set.
MCNS contribution: MCNS is part of this interesting research community, following the VLC enhancements and researching on the wireless light communication applications for the 6G and beyond networks. Part of MCNS research is based on the hot topics of LED-IoT communications in VLC networks, Intelligent reflecting surface (IRS)/reconfigurable intelligent surface (RIS)-aided VLC for 6G, Statistical modeling and channel estimation for VLC systems together with NOMA optical OFDMA/CDMA VLC networks.
6 minutes 
