LIFI COMMUNICATION
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SELECTING A LIFI STANDARD WHEN BUILDING YOUR LIFI PRODUCT
Selecting a LiFi Standard when Building your LiFi Product by Musa UNMEHOPA, Signify, The Netherlands
In this article we discuss design considerations when building a commercial LiFi product. LiFi is gaining traction as a means for fast, reliable, and secure communication in a world where our hunger for data and connectivity seems unsatiable. We define LiFi as an optical wireless communication technology that provides broadband wireless connectivity using modulated light. While today Radio Frequency (RF) based wireless systems (like Wi-Fi and 4G/5G) are dominant, there are use cases and application domains where RF communication poses challenges. In a previous article in this magazine [“A Closer Look at LiFi Standardization”, LpR #84, pp.42-45] [1] we introduced two potential standards for LiFi. These were IEEE 802.11bb [2] and ITUT G.vlc [3]. We explained that each has its merits, and both may co-exist and address different, complementary use cases and application domains. In this article we dive a little deeper and focus on how specific features of the communication protocol relate to the unique properties of light. We hope these considerations may aid you in your design decisions when developing a LiFi product or system.
Challenges with Radio Frequency Wireless Before we discuss the technical aspects, let’s first recall why LiFi is gaining so much interest as a wireless communications technology that can complement Wi-Fi local area networking and 4G/5G indoor mobile systems. We generally recognize three categories of challenges where RF communication is struggling, and we will briefly introduce each one.
Congestion The radio frequency part of the electromagnetic spectrum is finite, yet this scarce resource is in high demand due to the growing number of consumer devices and IoT sensors that need to be connected. The resulting spectral congestion and crowding of the radio channels causes performance degradation on the network. The light frequency part of the electromagnetic spectrum (both visible as well as invisible), while also finite, is orders of magnitude larger. And therefore, light communication can offer a welcome solution to the spectrum crunch available in the RF domain.
Electromagnetic Interference Another key aspect is electromagnetic interference (EMI). While a potential issue in any environment, especially for the use of wireless communications in industrial use cases, EMI can be a showstopper for RFbased networks. Tools and components typically used in industrial environments, like switching mode power supplies, arc welders, and motor brushes, can generate a significant amount of electrical noise in the RF spectrum range. Sometimes to the point where Wi-Fi cannot be used at all. The light frequency part of the electromagnetic spectrum is much less susceptible to electromagnetic interference, making LiFi communication systems much more suitable in these harsh industrial environments.
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Physical Security As radio signals propagate in all directions and pass through structural elements like walls and ceilings, you can never be sure who is eavesdropping on your conversation. Light, on the other hand, does not penetrate walls, ceilings, or coated windowpanes. You can direct your communication signal at the intended recipient and can be sure that your conversation literally does not leave the room. This directional, line of sight property of light adds an additional layer of physical security, on top of which you can run your regular link encryption. We see that there are some challenges with RF-based wireless communication, i.e., congestion of the RF spectrum, electromagnetic interference, and physical security. LiFi can successfully address these challenges, but the choice of communication standards is important. In the next section, we will outline how key features of the communication standards relate to some of the particular properties of light.
How do Both LiFi Standards Cope with Light? Neither IEEE 802.11bb nor ITU-T G.vlc were especially created from the ground up as a dedicated LiFi standard. IEEE 802.11 is of course the protocol suite for the popular Wi-Fi systems, while ITU-T G.vlc has its origins in wired home networking for coaxial cables, twisted pair, and power lines. The benefit of re-purposing an existing standard is that many tried and tested communication features can be reused and applied in the optical wireless domain. This applies equally to both IEEE 802.11bb as well as ITU-T G.vlc. But as neither standard was originally designed with LiFi in mind, some features of these standards fit better with the unique properties of light than others. In this section we will explore some of these features.
© 2021 Luger Research e.U. | LED professional Review (LpR) | Lighting Technologies & Design
Issue 88/Nov-Dec/2021