LiFi at the heart of future intelligent communications networks
Authors: Micheline Perrufel, Sylvain Leroux – ORANGE
Digital wireless technologies have revolutionized our communication habits but still have too limited convergence. Tomorrow, LiFi will accompany, alongside 5G, Fiber & Wi-Fi, exponential data consumption, but will require to redesign a more fluid, secured and intelligent global framework.
1/ Communication technologies
Analog communications were introduced with the advent of electricity. The modulation of the electrical signal then reproduced the pressure of the voice with varying degrees of fidelity.
With the increasing need to transmit more complex data such as video, analog solution rapidly became obsolete and unstable, as interferences became too important. Digital communications came with the computer age. The electrical coding 0 (for 0 volts) or 1 (for 5 volts) made it possible to more accurately translate the data to be transmitted. In 2021, less sensitive to interference, the digital solution still facilitates an increasing number of exchanges.
Over the past 40 years, increased traffic, more types of information being transmitted, connected objects and more varied user demand have led to the development of several communications technologies.
Digital wireless technologies primarily use the radio frequencies of the electromagnetic spectrum. From 0 to 300 GHz, the frequencies are free or licensed, i.e. accessible against payment of a right to use a block of X MHz. In exchange for the payment of a license, for example to deploy a mobile network, a guarantee of non-interference with other radio signals is offered.
Since 1991, digital mobile networks have gone through different generation. 2G replaced 1G with a new function in addition to voice: the transfer of small data. Then came the possibility to surf the internet, read emails, and play videos (3G). The ability to transfer large amounts of data and watch movies with high speeds (4G). Users quickly realised that every new version of a mobile network would enhance and replace the previous one. In parallel, telecom operators have worked to extend their networks to even larger areas.
In 2021, 5G v1 is associated with low or medium frequencies, e.g. in France 700MHz and 3.5 GHz, which offer even higher data rates and, more importantly, lower latency. In 2023, 5G v2 will be associated with new frequencies (26 GHz) to provide increasingly higher speeds and lower latency. It will also become an intelligent core network, delivering speeds adapted to the needs of connected devices.
To benefit from this new network features, smartphones must be both compatible with the frequency and the new technology.
The radio signal is broadcast through a network of antennas which is deployed, managed and maintained by Telecom operators. The signal range varies according to different criteria. The higher the radio frequency is, the less powerful is the mobile radio signal.
Source : Orange TGI/M Perrufel
Wi-Fi is a complementary wireless communication technology that uses unlicensed radio frequencies and that is transmitted via equipment such as routers, boxes, etc. called “Access Points” (AP). This technology allows voice communications, data transfers and exchanges between connected objects. The frequencies that are used are fairly homogeneous: 2.4 MHz and 5 MHz. A new frequency in 2021 will enrich the uses.
The Wi-Fi signal spreads up to several meters and can host a large number of users.
However, each Wi-Fi signal is shared among the different equipment/users. As these frequencies are unlicensed, they are also shared with other technologies, thus causing regular interference. Other radio frequency technologies can also disturb a Wi-Fi environment (such as Bluetooth and all 868 MHz technologies for example).
Wi-Fi security protocols (WPA2-WPA3) secure the transmission of information even though some vulnerabilities exist.
To be able to benefit from the new functionalities, a user must be equipped with:
– a Wi-Fi 6 or Wi-Fi 6E compatible equipment for example, with a processor and high frequency socket.
– a router or internet box that is also associated with high performance modules.
LiFi is a new optical wireless communication technology. Not using radio frequency waves, LiFi uses infrared (IR) or visible light (VLC), using unlicensed frequencies. In 2021, LiFi allows data communications, i.e. two-way access to the Internet for users, or data transfer between objects.
Based on the use of LEDs, LiFi technology generates a signal limited to the light area covered by the device (lighting device or not). One of the remarkable feature of LiFi is its very low latency. Each LiFi device deployed in a same room is an Access Point (AP) offering a guaranteed throughput for users (commercial offers in early 2021 offer throughputs up to 300 Mbps).
A LiFi AP can support multi-users and can cover an area between 2 and 25 m² (2021).
It is noteworthy that there is no interference between LiFi and all radio frequency technologies. The other notable feature is the quasi-symmetry of the upstream and downstream data rates, which differs from the other technologies mentioned above.
Wi-Fi and LiFi are additionally dependent on another optical technology called Fiber. Fiber is an optical wired technology mainly provided by telecom operators. It is usually distributed with a PON (Passive Optical Network – synchronous multi-channel) architecture, which is a good compromise as it allows up to 64 customers to share a Fiber. PON and soon XG-PON (allowing speeds up to 10Gbps) offer very high speed data transfers (still with the condition of using the new generation of routers & boxes). Fiber is a service both for businesses and consumers.
2/ Future intelligent networks
A- a new paradigm combining new standards of usages, social, environmental & technical disruptions:
Multiplicity of devices and IoT, Ultra High Speed, real time, autonomous cars, new environmental standards for building windows, factory 4.0, cyber threats, teleworking,… are all new contexts of use that will require future intelligent communications networks.
On the one hand, the growth of digital data exchanges requires high data rates, stability, availability and security. Global events such as Covid-19 have increased the number of teleworking, medical remote consultations, e-learning… On the other hand, the development of all these uses also increases concerns about the effects of radio frequency waves around us, obsolescence and scalability of devices and the global impact of uses on the environment (end-to-end electricity consumption).
The endless multiplication of these communication tools and connected objects intensifies the use and pressure on the availability of spectrum. The high availability of Optical Spectrum bandwidth should therefore be an attractive alternative.
Digital communication technologies are now ultra-efficient, allowing seamless communication thanks to the Horizontal Handover function. However, each technology has its strengths but also its limitations. In this respect, 5G has introduced a key concept for the next generation: HetNets, specially designed to provide a high quality of service mainly in indoor environments where demand is higher. And the end user does not want to focus on the technology, only on the experience. Multi-technology experiences and solutions will therefore become the new standard.
B- vertical handover
In case of insufficient signal strength, a data communication initiated from a technological solution is systematically interrupted. The user has to renew his call keeping the same network/technology or by changing the access mode.
Ultra-mobility, multiplicity of use cases, equipment, networks and communication technologies therefore require both pervasive and seamless communication. Automatic handover between different wireless communication solutions, called vertical handover, is currently not possible.
Future intelligent communications networks will therefore have to offer automatic (or manual) continuity between networks without any interruption. This is especially true in indoor environments, where radio signals are most challenged. As an high-speed wireless communication solution, with very low latency and enhanced security, LiFi can be smartly combined with Fiber, mobile networks and Wi-Fi, while reusing – partially – some of the existing infrastructure.
As Artificial Intelligence is increasing and spreading everywhere, why don’t we already talk about network/technology intelligence? The advent of LiFi and new compatible hybrid terminals should justify this new technological vision and necessity.
For the global benefit of all users and the entire ecosystem, intelligent networks must join forces as quickly as possible and has to be able to complement each other.
Micheline Perrufel and Sylvain Leroux will present at the 2021 edition of the Online Li-fi Conference. For more information, visit https://lificonference.com/program/