A team of researchers at the University of Massachusetts Amherst have introduced a new radio technology that allows small mobile devices to take advantage of battery power in larger devices nearby for communication.
Professor Deepak Ganesan and his graduate students at the College of Information and Computer Sciences, Pan Hu, Pengyu Zhang and Mohammad Rostami, have designed and are testing a prototype radio that could help extend the life of batteries in small, mass-market mobile devices such as fitness trackers and smartwatches. By using “energy offload” techniques they want to help make these devices smaller and lighter in the future.
They call the new technology Braidio for “braid of radios” and say that it can extend the battery life by 100x in some cases.
Currently the battery size in portable devices is proportional to the device size. The larger the device, the larger its battery; a laptop battery is roughly a thousand times larger than one in a fitness tracker, a hundred times larger than in a smartwatch, and 10 times larger than in a cell phone. However, these devices can’t take advantage of the differences. For example, the battery on a smart watch cannot survive longer by taking advantage of the higher battery level on a smartphone.
The researchers believe that like storage on the cloud, where multiple devices offload their data in to the cloud, devices should also be able to offload how much power they consume for communication to devices that have more energy.
The Braidio (a braid of radios) design is a radically new radio design that is capable of dynamic carrier offload i.e. the ability to dynamically switch the transmission carrier between the transmitter and receiver. The rationale for carrier offload is that the power consumption of communication is dominated by the cost of generating a carrier signal. Active radios generate the carrier at both the transmitter and receiver, therein the near-identical power consumption at both ends. Passive communication systems such as RFIDs generate the carrier solely at the reader end, hence they support highly asymmetric power consumption. The reader does most of the work and pays the majority of the energy cost of communication, while a tag, typically embedded in a smaller device or object, is extremely power-efficient. Thus, if we were able to combine the architectural building blocks of both active and passive radios, we can design a radio that is capable of moving carrier generation between the two end points. This capability can, in turn, enable power-proportional wireless communication wherein two devices with different battery capacities can multiplex between the different carrier generation modes such that they consume power in proportion to their available energy.
Braidio operates like a standard Bluetooth radio when a device has sufficient energy, but operates like RFID when energy is low, offloading energy use to a device with a larger battery when needed. So, when a smartwatch and smartphone are equipped with Braidios, they can work together to proportionally share the energy consumed for communication. Hu says their Braidio test results show that when a device with a small battery is transmitting to a device with large battery, Braidio can offer roughly 400 times longer battery life than Bluetooth, since the smaller device’s battery is preserved for longer.
These results only cover the cost of communication or transmitting data i.e if a radio is transmitting from a camera that consumes hundreds of milliwatts while using its sensor, clearly the sensors may dominate total power consumption and reduce the benefits of optimizing the radio.
The team designed Braidio’s radio frequency front end so that it could operate in different modes while consuming power comparable to a Bluetooth radio and using simple, low-cost components. They also designed algorithms that monitor the channel and energy at the transmitter and receiver and switch dynamically between modes to accomplish power-proportional communication without sacrificing throughput. With further optimization, the researchers believe Braidio or similar radios can be made smaller and more efficient for mass-market needs.
Wearable devices are often bulky due to large batteries needed for adequate battery life. We will need technologies like Bradio which allow us to have smaller batteries to enable thinner and lighter devices.
Read the Research Paper on Bradio.
