The potential of the proposed system is vast and includes applications such as battery-free wireless cameras, wireless monitors, sensors, skin-attachable sensing platforms, contact lenses, machine-to-machine communication and human-to-machine interactions, among others.
Mandi: Researchers at the Indian Institute of Technology Mandi are working towards developing efficient remote powering and communication technology for futuristic Internet of Things applications.
The Internet of Things (IoT) is a collection of objects (“things”) that can exchange data with each other through the Internet. IoT devices range from ordinary household appliances in a “smart” home to sophisticated industrial and scientific tools. These smart things are equipped with sensors, chips, and software that must be powered and stay in communication with other devices at all times. Simplistic power sources such as batteries may be unsuitable for such applications because of the constancy of power required, and because some of these “things” may be embedded or hidden, which makes changing batteries difficult. There is thus worldwide research in combining remote communication technology with remote powering options.
Shivam Gujral, Ph.D. Scholar, School of Computing and Electrical Engineering, IIT Mandi, said, “We have developed a cooperative model, in which, backscatter communication and radiofrequency energy harvesting (RF-EH) devices act together to optimally allocate the resources such as time and antenna weights.”
The team performed research on two such powering options – radio frequency energy harvesting (RF-EH) and backscatter communication. In RF-EH, energy is transmitted by a dedicated transmitter to the IoT device through radio waves, the same kind of waves that are used in mobile phones for communication. In backscatter communication, as before, power is transmitted via radio waves, but with/without the need for a dedicated transmitter. Instead, RF signals available in the vicinity, such as WiFi, cell phone signals, etc, are harnessed through reflection and backscatter to power the IoT objects.
The RF-EH and backscatter devices have their own strengths and drawbacks. For example, while the latter is associated with considerable energy savings compared to the former, it suffers from reduced data rate and a shorter transmission range. The IIT Mandi team has leveraged the complementary nature of these two technologies and judiciously combined them to achieve the desired Quality of Service (QoS) and efficiency using the power allotted to the system.
Siddhartha Sarma, Assistant Professor, IIT Mandi, mentioned, “We used a dedicated power transmitter for the two devices, in which the backscatter device transferred information through a monostatic configuration and the RFEH device through the HTT protocol. The team used extensive numerical simulations to establish the superiority of the proposed cooperative scheme over existing schemes. In these simulations, key parameters were varied to analyze the performance of the model.”
Researchers plan to implement the joint radiofrequency energy harvesting-backscatter communication system in real-time to analyze system performance. This would include working on the hardware aspects of the two complementary technologies. The potential of the proposed system is vast and includes, in addition to IoT devices, applications such as battery-free wireless cameras, wireless monitors, sensors, skin-attachable sensing platforms, contact lenses, machine-to-machine communication, and human-to-machine interactions.
