Wireless mesh nets offer bright prospects for lighting control

August 30, 2011 //By Peter Rand
Wireless mesh nets offer bright prospects for lighting control
Smartphones and tablets are becoming omnipresent, and there is rapid growth in user acceptance of these devices as interfaces to anything electronic. That makes smartphones and tablets a natural extension of a lighting control system.

A simple gateway from Ethernet/Wi-Fi/USB to low-power wireless can ensure that users have access to all features of their lighting control system through their smartphone or tablet. Texas Instruments demonstrated the concept at Mobile World Congress this year using the Android-based ZigBee Home Automation lighting application running on a mobile platform.

The low-power requirements of the network and regional nature of RF regulations make it unrealistic to design a wireless lighting network topology that requires all nodes (lights, switches, sensors and remotes) to be in the RF range of a single coordinating node in the network. The solution is an even distribution of routing nodes throughout the building to extend range without increasing power—that is, mesh networking.

Lamps constitute the ideal backbone for a wireless mesh network. A good mesh network is self-forming and self-healing, and can deal effectively with a high number of nodes in diverse topologies.

Compared with a radio at 2.4 GHz, sub-1-GHz radios yield longer range and better penetration for the same amount of power. For that reason, sub-1-GHz solutions are often preferred for outdoor applications such as street and city lighting. There is also generally less interference to deal with in the sub-1-GHz bands, as Wi-Fi gear and microwave ovens do not operate in that range. Radio interference is present in all the open ISM bands, however, and it is thus important that the radio have sufficient output power and a receiver with good selectivity (adjacent channel rejection) and blocking to filter out unwanted signals.

But there is no globally available sub-1-GHz band. That forces development of regionally specific end products—supporting, for example, 868 MHz in Europe or 915 MHz in the United States.

Figure 1: Low-power wireless lighting control.
Click on image to enlarge .


Commissioning with traditional lighting is intuitive but expensive; whichever lights are connected after a breaker switch will be controlled by that switch. Wireless adds flexibility in terms of

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