Use powerline communication and Bluetooth for smart home applications

A good smart home system must be simple to install and use.  For the lowest cost, it should leverage the infrastructure that is already present in a home.  It is also important that any smart home interface is both user-friendly and can provide generic access to the broad range of consumer appliances found in a modern home.  Finally, consumers require a simple interface that makes it possible to set rules for their home’s energy use. They want more options to be available, but they want them to be simple to execute.

Providing the right infrastructure for connecting these devices will determine the success of the smart home. The infrastructure must be easy to set up, inexpensive to install and maintain, and must perform well. The supporting infrastructure should be as easy as possible to set up and the effort to maintain this infrastructure should be minimal. Many existing networking technologies compete to support this mission. For example, a comprehensive Ethernet network can be constructed around the house.

Alternatively, wireless networks such as 802.11x, Bluetooth, and HomeRF can be constructed by installing multiple interconnected wireless access points and base stations within the home. However, the devices themselves would need wireless capabilities, and the above three infrastructures all require significant effort and cost to build up the networks externally.

In this article we advocate the use of a mixed system, where existing electrical wiring and outlets are used as the medium for data communication within the home and the user interacts with the system wirelessly via a Bluetooth enabled device such a mobile phone, PC, or PDA. An adapter will serve as the bridge between the two networking technologies as shown in Figure 1 below.

Powerline communication technology and smart homes

"Imagine: Entering your house, you unpack and plug in your newly purchased flat-panel TV. Simply and quickly - the TV automatically connects to the cable box, the DVD player, the Digital Video Recorder, the Home Theatre system, and also to the Internet."

This is quote taken from the website of the HomePlug Powerline Alliance is the experience promised by Powerline Communication (PLC). Powerlines are the largest infrastructure; there are outlets at every corner of the house making it an all-encompassing network. Powerline networks use a bus topology which provides a high level of reconfigurability coupled with the ability to control more than one device from one controller. The controller is able to keep track of all the devices on the network, which provides the backbone for expandability and “plug and play” installations where any new device can immediately become a part of the network.

After a system is deployed in the field, it may require updates in the future to either add features or fix bugs in the application. If the systems are connected on a communication bus, then any updating process could be performed over the communication bus. This way, the update could be sent from one central location, saving time and money. With PLC, a field update can be performed without adding any additional components. The reception of data from the powerline and the update of the application code can be performed in one device.

Since most electronic devices already use power outlets to receive power, standards were created that allowed these same power outlets and electrical wires to connect to the different forms of hardware, electronic and communication interfaces to each other. Some examples of the major groups are the HomePlug Alliance and the Universal Powerline Association. These specifications promote interoperability with other similar certified products and do not interfere with other home networking technologies such as phone lines and structured wiring. This makes PLC an ideal networking technology for enabling the smart home.

Bluetooth and smart homes

Bluetooth technology is by far the most successful of any of the short range wireless standards.  Bluetooth was conceived with the mobile phone as the center of the network. As noted on the Bluetooth Special Interest Group website, Bluetooth has been around for just over ten years (twice as long as ZigBee) and outsells all of the other short range standards put together, with over 1 billion chips shipped every year.  The very first Bluetooth products can still communicate with new ones that consumers buy today – something that neither 802.11 nor ZigBee can claim. Equally important, over the decade it has been shipping, it has evolved to address all of the key requirements of the smart home market.

• Robustness: Bluetooth technology is the only frequency hopping standard.  That makes it reliable within the home environment where the spectrum is unpredictable and likely to get more congested over the life of the meter.  It is more resilient that either ZigBee or Wi-Fi and far more difficult to intercept, meaning that it is much less susceptible to hacking attacks.
• Coexistence: Bluetooth technology is the only wireless standard that includes coexistence mechanisms to maintain performance in noisy environments.  That means that it continues to work when new radios are introduced into the home.
• Long Range: The latest Bluetooth chips provide ranges as good as any other 2.4GHz technology, at significantly lower operating power.
• IP support: Bluetooth technology already has IP support (which the smart metering industry requires) with its BNEP protocol.
• Proven security: Bluetooth technology has mature security that has evolved to cope with a variety of security attacks, along with well tested implementations that have proven to be resistant to hacking.
• Licensing: The royalty-free license model of the Bluetooth SIG extends to all versions of the technology.

Currently, a great many portable devices come with a built-in Bluetooth which is accessible to the developers in their applications. This enables the use of software developed for notebooks, smartphones, or any other portable device into smart homes. Each portable device has its own computing and communications resources and enables the use of sophisticated user interfaces and complete data analysis at no added cost.

Smart home applications

Smart homes are not limited to controlling just appliances, and they can be designed as advanced systems for home security, temperature and lighting control, and other applications.

For example, to protect against break-ins, consumers can position web cams at home entrances and install an alarm system that uses heat and motion sensors to alert homeowners and remote security companies in the case of an intruder. In the case of fire, a smoke detector can be wired to sound not just an alarm but also to send a signal to the air-conditioning system fans to shut down to prevent feeding the fire, alert the homeowner and specified contacts, and illuminate an evacuation route through the house.

Alternatively, energy savings can be realized by automating control of thermostats, lights, and other environmental systems such as garden sprinklers and fountains. Integrating all of these into one environmental system can help ensure a minimum waste of energy in your home. For example, on a hot, sunny day, weather sensors can activate blind and drapery controls to shade the home while ensuring that the garden receives adequate irrigation at the right time of day. Motion and occupancy sensors can activate heat and lighting controls as people enter and exit rooms.

New lighting technologies such as LED or induction use as much as 90 percent less energy than bulbs based on older technology with the same lumen output, and last 50 to 100 times longer. That's a great start, if you want to save energy. Smart lighting systems can offer features such as light harvesting, optimized lighting levels, dynamic lighting output based on sensors, and dynamic or on-demand color shifting. What's more, smart light fixtures can communicate impending failure, which can help reduce maintenance costs.

An example of a smart home application already in production is ROSIE developed by Savant that uses an iPod Touch, iPhone, or iPad to control devices with ROSIE services on a home network.

About the Authors

Rohan Gandhi is an Applications Engineer for the Powerline Communications group at Cypress Semiconductor. He has 1.5 years of experience designing and working with Powerline Communications and lighting. He has recently completed his Bachelors in Electronics and Instrumentation from BITS Pilani, India. He can be reached at: rosg@cypress.com

Rahul Parsani is an Applications Engineer for the Powerline Communications group at Cypress Semiconductor. He has a Bachelor's Degree in Electronics and Instrumentation Engineering from the Birla Institute of Technology and Science Pilani, Goa Campus. He can be reached at rarp@cypress.com.