UMass Amherst introduces ‘Braidio’ technology, lets mobile devices share power
In a paper presented Aug. 25 at the Association for Computing Machinery’s special interest group on data communication (SIGCOMM) conference in Florianópolis, Brazil, a team of computer science researchers at the University of Massachusetts Amherst led by professor Deepak Ganesan introduced a new radio technology that allows small mobile devices to take advantage of battery power in larger devices nearby for communication.
Ganesan and his graduate students in the College of Information and Computer Sciences, Pan Hu, Pengyu Zhang and Mohammad Rostami, designed and are testing a prototype radio that could help to extend the life of batteries in small, mass-market mobile devices such as fitness trackers and smartwatches. They hope using “energy offload” techniques may help to make these devices smaller and lighter in the future.
Ganesan and colleagues have dubbed the new technology Braidio for “braid of radios,” and say it can extend battery life hundreds of times in some cases.
As he explains, 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, Ganesan says, “the battery on your smart watch cannot survive longer by taking advantage of the higher battery level on your smartphone.”
“We take for granted the ability to offload storage and computation from our relatively limited personal computers to the resource-rich cloud,” he adds. “In the same vein, it makes sense that devices should also be able to offload how much power they consume for communication to devices that have more energy.”
In the paper presented at the conference, to be published in the conference proceedings, the researchers show that they have made strides toward fixing this problem, designing a radio that has the ability to offload energy to larger devices nearby and, in effect, making both device size and battery consumption proportional to the size of battery.
To achieve this, they embellished Bluetooth, a commonly-used radio technology, with the ability to operate in a similar manner to radio-frequency identification (RFID), which operates asymmetrically. That is, a 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.
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, they explain.
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 longer.
“To be clear, our results only cover the cost of communication or transmitting data,” Hu adds. “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.
Ganesan says that technologies like Braidio open up a new way of thinking about the design of mobile and wearable devices. “Wearable devices are often bulky due to large batteries needed for adequate battery life,” he says. “Perhaps such energy offload techniques can reverse this trend and enable thinner and lighter devices.”
Learn more: Extending Battery Life for Mobile Devices
MSU chemists created a material able to enhance a charge rate of li-ion batteries drastically
Nowadays Li-ion batteries power a wide range of electronic devices: mobile phones, tablets, laptops. They became popular in 90s and subsequently ousted widespread nickel-metal hydride batteries.
However, Li-ion batteries suffer a number of disadvantages. For example, their capacity may drop when temperature falls below zero. The price is also discomforting, which is mostly caused by use of expensive lithium-containing materials. For instance, Li-ion batteries make about half a price of a popular electro car Tesla Model S. On the other hand, Li-ion batteries are compact, easy to use and highly capacious, which means that your device would live long having a relatively small battery.
A key element of the Li-ion batteries limiting its capacity is a material used for its cathode. For the majority of the materials their capacity limit has already been reached. Hence, scientists and engineers are actively searching for new cathode materials capable of recharging completely within minutes, operate under high current densities, and store more energy.
One of the most prospective classes of cathode materials for a new generation of Li-ion batteries are fluoride-phosphates of transition metals.
The work directed by Prof. Evgeny Antipov (correspondent member of the Russian Academy of Sciences and the head of the MSU Electrochemistry Department) was carried out by a team of MSU research scientists together with their Russian and Belgian colleagues. It was devoted to creation of a new high-power cathode material based on a fluoride-phosphate of vanadium and potassium for Li-ion batteries. The results were published in Chemistry of Materials(current IF — 8.354)
‘The work is based on a simple idea of geometric and crystal-chemical conformity of ionic sublattices,’ — says Stanislav Fedotov, one of the authors, junior research scientist at Electrochemistry Department, Faculty of Chemistry, MSU.
The scientists succeeded to stabilize a unique crystal structure, which provides a fast transport of lithium ions through spatial cavities and channels. Consequently, the suggested cathode material demonstrated high charge/discharge rates (down to 90 seconds) retaining more than 75% of an initial specific capacity. With its morphology and composition optimized, this material may become a serious contender to such well-known and commercialized high-power cathode materials as NaSICON.
According to the authors, the results of the presented work may not only open up ample opportunities in searching and further synthesis of new cathode materials for Li-ion batteries, but also promote the development of a new battery type where a role of a mobile ion (a charge carrier) would be performed by potassium ions instead of lithium.
‘It is assumed that such batteries would not only deliver high energy density, but would also be economically attractive due to a replacement of expensive lithium-containing components with cheaper and hence affordable potassium-containing analogues’ — explains Stanislav Fedotov.
Learn more: New material to enhance battery life