TI recently demonstrated a crockpot with an embedded Wi-Fi device (CC3000) that lets you cook meatballs from anywhere. We can say that the Internet of Things (IoT) is really coming to fruition. However, other than being able to cook meatballs remotely, a large portion of the IoT will actually consist of sensors. Such sensor nodes spread out over a home, building, or factory can help with energy management, comfort enhancement, security, and diagnostics amongst other applications.
Battery life is a key consideration when implementing a sensor network as many battery-operated sensors may be in inaccessible locations. Additionally, changing batteries in billions of sensor nodes poses huge operational and environmental costs. Radio power of these wireless nodes is a major cause of battery drain. RF standards such as ZigBee are popular in low data rate, low power applications. ZigBee and other low power RF standards use MAC and PHY layers defined by IEEE 802.15.4. An amendment to 802.15.4, called 802.15.4e uses a duty-cycled MAC to reduce radio power consumption. Even if the radio is duty-cycled, it still consumes a majority of the current in the application. TI has made further improvements to the Time Synchronized Channel Hopping (TSCH) and Co-ordinated Sampled Listening (CSL) MAC protocols of 802.15.4e to increase battery life of wireless sensor nodes to last 3 years on two standard AA batteries. This represents more than 75% improvement over battery life of existing sensor nodes. A demo of this wireless sensor network solution can be seen on TI's e2e site.
Additionally, TI has also developed a Hybrid Sensor Network solution that supports Power Line Communication (PLC) and RF in the same node. This is especially valuable in Building and Industrial Automation where the sensors might be spread on different levels of the building making it hard for RF signals to pass through. The Hybrid Sensor Network increases reliability as well as battery life of the wireless nodes by routing data through PLC when possible. In cases where noise on the power line prevents effective PLC communication, the hybrid nodes seamlessly switch to use RF to transmit signals. By using Hybrid Sensors on the network, the battery life of wireless sensors can be increased to up to 10 years on two standard AA batteries and robust recovery of network paths is made possible.
Increasing battery life is a key enabler to the true proliferation of the Internet of Things. TI's enhancements to the 802.15.4e MAC is an important step towards increasing battery life of wireless sensor nodes. Whenever hybrid sensor nodes are added to the network, it can further enhance battery life of the wireless nodes, as well as significantly increase robustness of the network.
