Table of Contents Hide
- 1 About Wireless Lighting Control
- 2 Wireless Connectivity: the Blood Vessel of Smart Lighting
- 3 Facilitating Automatic Lighting Control
- 4 How Wireless Lighting Control Works
- 5 Network Topology
- 6 Wireless Protocols
- 7 How Smart Devices Connect to Lighting
About Wireless Lighting ControlWireless lighting control refers to over-the-air management of lamps or light fixtures using wireless communication technologies. Wireless control not only simplifies design, installation, commissioning, and operation of lighting systems, but it also provides a way for users to make a single environment flexible enough to accommodate various visual needs. Wireless lighting control is a plug and play solution, meaning there is no need for costly, complicated hardwiring as well as complex light management that uses traditional lighting control protocols. The transition from traditional lighting systems to connected solid state lighting (SSL) systems drives a whole new set of requirements for lighting control, especially around Internet of Things (IoT) which refined the concept of smart lighting.
Wireless Connectivity: the Blood Vessel of Smart LightingSmart lighting systems increasingly rely on ubiquitous wireless connectivity to transmit control signals. The digital nature of LED technology enables lighting products to become digital data nodes and allows them to participate in the Internet of Things. Smart lighting is no longer just about dimming or switching on/off in response to sensors and timers. While smart lighting continues to make use of control signals provided by local sensors and controllers, smart lights can be programmed to respond to application logic provided by online rules engines or can leverage data and environmental parameters collected from a host of interconnected devices such as fire/smoke/CO alarms, thermostats, HVAC controllers, security cameras, remote doorbells, humidity monitors, energy usage monitors, and smart utility meters.
At the most basic level, smart lighting is all about wireless connectivity. The ability of a connected lighting system to share information, facilitate interoperation and support interaction between a scalable number of lighting nodes is built on its wireless networking capabilities. Wireless networks don't just eliminate messy cables to reduce installation cost and enhance deployment mobility, they provide advanced interoperability that allows devices from different vendors or devices with different functionalities to exchange data. Today's smart lighting systems deal with how to integrate the various digital nodes into a collective whole. A high degree of interoperability among heterogeneous types of ever-increasing numbers of geographically dispersed sensors, devices and end points simplifies network management, enhances data transmission security, reduces the risk of device or manufacturer obsolescence, and makes the smart lighting infrastructure future proof.
Facilitating Automatic Lighting ControlSmart lighting is essentially a convergence of wireless networking and automatic lighting control. There are a variety of lighting control strategies that are designed to deliver the correct amount of light and/or the desired lighting effect, where you want it, when you want it. Dimming, occupancy control, daylight harvesting and time scheduling are the most commonly used strategies.
Dimming control allows adjustment of light intensity of a light source. Dimming effectively reduces energy consumption and supports designs where complex layers require careful balancing of luminous contrast layers. The most commonly used control methods used to dim LED loads include 2-wire forward phase (leading edge), 2-wire reverse phase (trailing edge), 3-wire forward phase (leading edge), 4-wire 0-10VDC, 4-wire DALI (Digitally Addressable Lighting Interface), and pulse width modulated (PWM) dimming. In smart lighting applications, dimming is typically not used as a stand-alone lighting control feature. It works in tandem with following automatic lighting control strategies to provide intelligent dimming control.
Occupancy control strategies use microwave, passive infrared (PIR), or ultrasonic sensors to detect the presence of an occupant and accordingly signal a connected controller to turn lights on or off and adjust the light output. Microwave detectors emit high-frequency electromagnetic wave (5.8GHz) and measure the change in the reflections as the signals bounce off moving objects. PIR sensors detect heat radiation of moving objects. Ultrasonic sensors detect a frequency shift in the emitted and reflected ultrasonic waves.
Daylight harvesting is a strategy to dim or switch lights when natural daylight detected by a photosensor in an area is higher than the threshold value.
Time scheduling uses a time clock or software-based intelligence that is built into the light controller to trigger pre-set on/off or dimming control.
The complete suite of smart lighting features can only be enabled when the sensor- or logic-embedded lighting nodes are able to communicate. Wireless sensor networks (WSNs), as a critical part of the IoT architecture, collect data about the environment and communicate it to gateway devices which relay the information to and from a centralized cloud platform over the Internet. The WSN delivers data-driven intelligence from a central network server to smart lights, enabling lighting control strategies to be executed in a truly smart way.
How Wireless Lighting Control WorksWhen we talk about wireless control, it's not about wireless control signals transmitted through the air using wireless infrared (IR) energy. Wireless lighting networks typically operate at a radio frequency (RF) between 100 MHz and 5.8 GHz. A lighting infrastructure that use radio wave for device communication typically consists of these components:
- A driver (for LED lighting) that translates the effect of the control signal into corresponding light output.
- A controller that assigns commands to the driver to execute a lighting change. It receives input from connected sensors or from the network server via a gateway.
- A wireless communication module that is usually integrated with the controller to provide two-way communications.
- A gateway or hub that acts as an intermediary to relay messages between lighting devices and a central network server.
- A network server that handles all the intelligence and complexity associated with managing the lighting network.
- A software platform that acts as a mediator between the hardware and application layers. It provides an interface to initiate data and device management.
In the context of Internet of Things, wireless lighting control is implemented at the physical and network layers. The physical layer (or device layer) defines the electrical and physical specifications of the data connection as well as the protocol to establish a connection between lighting devices. Also known as transmission layer, the network layer is responsible for securely transferring data packets between lighting devices and the network server or information processing system.
Wireless lighting systems typically have a device-to-gateway architecture in which the physical layer communicates with application layer via network layer. The application layer provides centralized device management and realizes various practical applications based on the information processed in the software platform. The gateway at the edge of the network establishes secure wireless connections with multiple lighting points and connects to the network server via standard IP connections. As you can see, the gateway must provide protocol translation to mediate the communications between the physical layer and application layer.
Aside from device-to-gateway communication model, device-to-device wireless communication becomes increasingly important in industrial IoT lighting applications. Sometimes referenced as M2M (machine to machine communication), device-to-device communication allows smart lights to talk to one another and exchange the data through routing and forwarding, without the need of protocol translation nor advanced data processing. Local interactions between lighting points through wireless PAN networks enable collaborative operations that open up further possibilities to increase automation.
Network TopologyFor wireless lighting to thrive, a robust connectivity topology is crucial. Topology describes the interconnections of lighting nodes in a network. The topology of a wireless lighting system makes all the difference when it comes to reliability, resilience, transmission distance, communication rates, and numbers of nodes. The two fundamental network topologies for wireless lighting systems are star and mesh. In a star topology, a central node managing connections with many peripheral lighting nodes. The central node is the hub, or access point (AP), that connects to the internet. In a star topology, peripheral nodes do not talk to each other unless the central node forwards the message.
The mesh topology is an interoperable networking solution that can extend a network range through multiple hops and offers excellent scalability and reliability. In a mesh network, nodes are all connected to each other. Each node has processing power and memory to support the routing function. This allows the intelligence of a lighting system to be replicated in every node and, in such a way, avoids the single-point of failure issue that typically happens on wireless networks using a star topology.