Until recently, lighting systems operated as localised points of illumination. However, this function is evolving as our dependence on connectivity and data continues to increase. Connected lighting systems (CLSs) blend LED capabilities with IoT connectivity to enable design engineers to simultaneously provide illumination and transfer data. With the IoT as the data collection platform, CLSs will save electrical energy while opening up new avenues to provide a range of services and benefits to people and organisations.
By Paul Golata
At the core of the CLS is an emerging optical wireless communication technology called Li-Fi, short for light fidelity. Introduced in 2011, Li-Fi uses IEEE 802.11 protocols and has gained momentum, becoming a viable alternative to the ever-shrinking Wi-Fi spectrum and is evolving towards making lighting a central point in smart infrastructure. In this article, we explore the role of IoT technologies, Li-Fi’s ability to transfer data through lighting, and technologies that need further development, all of which will ensure CLSs develop to their full potential.
The role of IoT
The IoT is a technological revolution. Smart sensor technology and wireless connectivity have led design engineers to focus on how to sense and collect data as well as how to get it into a digital domain for Web handling and manipulating. Sensors, connectivity and digital data make up the foundation for further CLS development.
Optical sensors: Sensors are everywhere, measuring aspects like humidity, temperature, pressure, air quality, vibration, and volatile organic compounds (VOC), to name a few. Sensors detect analogue signals generated from the physical world and then convert them into digital data signals that can be controlled and manipulated by embedded systems (Figure 1). Optical sensors convert light energy into readable electrical signals that can detect whether lights are on or off, as well as measure light intensity.
Wireless connectivity: Wi-Fi is a technique that allows devices to con nect to a wireless local area network (WLAN). Wi-Fi uses electromagnetic radiation in the radio frequency (RF) spectral range (20kHz–300GHz), at five primary frequency ranges: 2.4GHz, 3.6GHz, 4.9GHz, 5GHz and 5.9GHz. Currently, most consumer products focus on one or both of the 2.4GHz and 5GHz frequencies. Wi-Fi has drawbacks, however, including a susceptibility to being hacked and a spectrum that’s already nearing capacity.
Digital data: It is easy to store digital data for future use. Combined with a future in which artificial intelligence (AI) and Big Data analytics (BDA) curate, apply, extend and leverage this data, the designer’s aim is to bring illumination systems into this overarching technological framework. IoT promises to enable a variety of end-to-end solutions that are more intelligent.
Li-Fi or optical wireless communication: As mentioned earlier, CLSs blend LED capabilities with IoT connectivity, enabling design engineers to simultaneously provide illumination and transfer data. At the core of these systems is solid-state lighting (SSL), which uses LEDs as sources of illumination, rather than filaments, plasma, or gas. LEDs offer designers a palette of  options, such as quick modulation between being on and off; and the ability to control colours and output lumens. They’re also known to be long-lasting, compact, durable and energy-efficient, making them a good option for further application.
As an optical wireless communication (OWC) technology, Li-Fi has evolved to deliver data via visible light. While Wi-Fi uses radio waves to deliver data, Li-Fi uses infrared, ultraviolet, and visible light waves, which offer several advantages.
Currently, the Wi-Fi spectrum is crowded to a point nearing a crisis, but the visible Li-Fi spectrum is nearly 10,000 times larger than its RF counterpart. Li-Fi can also offer data rates that are competitive with Wi-Fi, with reliable, high-quality transmission speeds of >30Mbps. What’s more, Li-Fi uses Line of Sight (LoS) architecture, which makes it highly immune to hacking; data usually disappears when a hacker intercepts the data stream.
An LED’s ability to modulate on and off quickly is key to why Li-Fi works. Data moves from one location to another through these modulation and demodulation processes. Li-Fi operates by taking streaming data content and inserting it into an SSL driver, which can run a string of LED lamps, turning them on and off at high speeds. As the LED lamps turn on and off, strobing faster than the eye can see, they illuminate the required area.
Within this area is a Li-Fi dongle, an integrated device that connects to a computer and contains a photo-detector to sense the light. It responds by producing an electric current in proportion to the amount of light impinging on its surface. The tiny electrical signal passes into an electronic circuit with amplifiers that boost the signal. Further signal conditioning and processing occur before the signal leaves the dongle through a wireless connection to a device, such as a laptop, portable computer, mobile device, or mobile phone.
A unified whole: Products, systems and software
Several years ago, LED manufacturers began prioritising the creation of a unified solution—that is, a lighting system capable of interacting with all the various electro-mechanical systems in one place. With the boom in the IoT space, this initiative revealed three levels of differential, sustainable support that was necessary to enable the potential of CLSs using hardware, IoT, software, and interface assets.
Hardware assets: Hardware assets equire the packaging of LED components and the use of electronic drivers to control the current that passes to the LED components. Designers also must consider the related electro-optical-mechanical functions to ensure these devices can work together and be transformed into successful luminaires. Hardware designs may require thermal heat sinking, mounting, packaging, optical control, and integration with items that the luminaire will have to interface with (using common and applicable design codes).
Adding intelligent sensors to obtain analogue information and convert it into digital information is also part of this design effort. In short, the suppliers should focus on how all the related hardware components work together.
IoT assets: Hardware, however, is not enough. A robust CLS design requires additional measures to enable it to connect to and work in synergy with other lighting systems successfully. CLS suppliers must address systems integration issues, including data security. How will data be secure from unauthorised users that attempt to take control of it? Data security may require authentication, which protects sophisticated keys that authorise access. Back-end storage, computers servers, and analytics also require thought. When entering the realm of IoT, CLS designers must ensure that the pathway to get data onto and off the CLS is available, reliable and robust.
Software assets: IoT provides a broad array of services never possible before, by way of the cloud. In the new world of IoT, CLS providers that offer cloud based technology services
to support their offerings will have a competitive advantage because they allow their customers to obtain the maximum benefits from their products, immediately.
Future interoperability is paramount to fast growth. Standard solutions, which allow multiple suppliers’ products to work seamlessly together over time, provide economic incentives and benefits. Solutions that cannot work well with other products will find themselves at a competitive disadvantage, as the need to be able to cross domains and boundaries without issues will be primary.
Another area that CLS suppliers must address is common application programming interfaces (APIs). The US Department of Energy (DOE) has realised that this is a major hurdle that needs to be overcome to achieve some of the desired energy benefits of CLS. SSL is more efficient when it comes to saving energy. However, SSL, in the form of multiple CLSs that connect to the IoT will empower the cities of tomorrow to be even more efficient. This increased efficiency will result from CLS being combined with SSL and IoT within a smart grid, allowing coordination among offices, buildings, homes, retailers, streetlights, etc, so that they all work as an optimised, whole system instead of individually.
The data that smart sensors obtain, combined with data analytics, will work to make adjustments that save money for each location within the unified system, which would not
be possible if the location was left unconnected from the whole. The DOE suggests making APIs readily available for users, while the lighting industry looks at adopting common approaches to security that seek to minimise systems integration issues for the industry.
LED light sources have become an avenue by which lighting can move from analogue to digital, making life easier—via the IoT. Li-Fi offers the potential for CLSs to both provide light and transfer data. With these capabilities, lighting systems could offer an alternative to the ever-shrinking Wi-Fi spectrum to make lighting the hub in smart infrastructure. Connected lighting innovation promises a future that is even brighter than the world we live in today. But as with many future innovations, seeing is believing.
Paul Golata joined Mouser Electronics in 2011 as a senior technical content specialist. He has earlier worked in manufacturing, marketing and sales, at Hughes Aircraft Company, Melles Griot, Piper Jaffray, Balzers Optics, JDSU, and Arrow Electronics. He holds a BSEET from DeVry Institute of Technology – Chicago, IL; and an MBA from Pepperdine University – Malibu, CA.
