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Low‐Latency, Low‐Power technologies and communications devices are required for IoT Networks

The Internet-of-Things is an emerging revolution in the ICT sector under which interconnecting physical objects communicate with each other and/or with humans over internet in order to offer a given service.  The Internet of Things (IoT) is a system of interrelated computing devices, mechanical and digital machines, objects, animals or people that are provided with unique identifiers (UIDs) and the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. These objects can be anything from large buildings, industrial plants, planes, cars, machines, any kind of goods, and even to human beings, animals and plants.


The Internet of Things (IoT) is expanding rapidly, creating an environment of devices and sensors that in many cases will function entirely on batteries. In some use cases where batteries are difficult or even impossible to change (environmental sensors, etc.), the length of the battery life may determine the useful life of the device.


However battery life has often been dictated by how long the device stays “awake.” The longer the device sleeps, the longer the battery lasts, but at the expense of performance. A new technology is required that extends battery life without affecting performance. These devices will have many applications, including smart homes, smart warehouses, wearable health monitors, logistics and transportation, and many, many more. It is estimated that companies will spend close to $5 trillion on the IoT over the next five years.


Currently, the majority of Internet of Things devices rely on cellular networks. The vast amount of data on these networks, however, slows the rate at which it is processed. According to Shields (2017), “That also creates high latency – the amount of time between when data is sent from a connected device to when it returns to the same device – which in turn limits IoT solutions’ effectiveness.” Low latency is ideal for devices to work efficiently.


Low latency often comes at the price of high power usage, however. Faster data transfer usually requires devices to expend more energy. As a result, we need a mechanism for reducing latency while conserving power. Recharging and replacing batteries for the multitude of IoT devices will become extremely cumbersome. According to Maria Guerra (2017), “Designers of IoT solutions are relying on power management solutions to efficiently handle the power needed to energize a wide range of IoT devices, as maintenance and battery replacement are not cost-effective approaches.”


There is great potential for IoT technologies to revolutionize modern warfare, leveraging data and automation to deliver greater lethality and survivability to the warfighter while reducing cost and increasing efficiency.


IoT will impact military operations in the very near future, raising many challenges but also providing many potential benefits. However, determining how to integrate IoT technologies into the military ecosystem and how to efficiently leverage them still requires addressing many research challenges due to constraints such as intermittent links, low bandwidth, differing levels of security classifications, and low power of mobile devices.


Communication of data between devices is a power consuming task, specially, wireless communication. Therefore, we need a solution that facilitates communication with low power consumption. Routing protocols with low memory requirement are required.


Many applications in, for example, the automotive industry, health care and manufacturing are mission or safety critical and have stringent deadlines. In cooperative driving, for example, autonomous vehicles have to wirelessly coordinate their planned trajectories within milliseconds when approaching an intersection or changing a lane. Such applications demand reliable wireless networking at a message latency and energy efficiency that today’s approaches cannot provide.


Communication technologies are required that are robust to signal interference and/or loss of network operation. The utility of emerging civilian mobile waveforms such as 4G/5G LTE for military applications need to be explored.

Why We Need Low-Power, Low-Latency Devices

Wake-Up Radio from IEEE 802.11ba standards task group is the solution to this challenge. This low-power, low-latency solution will allow our devices to work efficiently without expending considerable amounts of power.


ActLight: Ultra Small, Very Low Power Consumption Heart Rate Monitoring Sensor

Long battery life, precision of measurements and very small size are the key requirements for vital signs monitoring sensors in hearable devices.


Despite ultra small detector area (<0.2mm2) and minimal LED power (<1uW/Hz), the sensor delivers convincing >70dB SNR. In addition, the ActLight solution provides a very strong output signal without AFE, further reducing the power consumption of the overall system.


The Dynamic PhotoDiode is the vital signs monitoring sensor of choice to meet the very demanding technical requirements of the hearable devices market.


Teeny-Tiny Bluetooth Transmitter Runs on Less Than 1 Milliwatt

Engineers at the University of Michigan have now built the first millimeter-scale stand-alone device that speaks the  lowest energy version of Bluetooth, called Bluetooth Low Energy (BLE). Consuming just 0.6 milliwatts during transmission, it would broadcast for 11 years using a typical 5.8-millimeter coin battery. Such a millimeter-scale BLE radio would allow these ant-size sensors to communicate with ordinary equipment, even a smartphone.


The transmitter chip, which debuted last month at IEEE International Solid-State Circuits Conference, had to solve two problems, explains David Wentzloff, the Michigan associate professor who led the research. The first is power consumption, and the second is the size of the antenna. “The size of the antenna is typically physics-based, and you can’t cheat physics,” says Wentzloff. The group’s solution touched on both problems.


An ordinary transmitter circuit requires a tunable RF oscillator to generate the frequency, a power amplifier to boost its amplitude, and an antenna to radiate the signal. The Michigan team combined the oscillator and the antenna in a way that made the amplifier unnecessary. They called their invention a power oscillator.


The key part of an oscillator is the resonant tank circuit: an inductor and a capacitor. Energy sloshes back and forth between the inductor’s magnetic field and the capacitor’s electric field at a resonant frequency determined by the capacitance and inductance. In the new circuit, the team used the antenna itself as the inductor in the resonant tank. Because it was acting as an inductor, the antenna radiated using a changing magnetic field instead of an electric field; that meant it could be more compact.


However, size wasn’t the only thing. “The big advantage there is that the antenna is a much higher quality factor inductor than on-chip inductors,” says Wentzloff. Quality factor, or Q, is a dimensionless quantity that basically says how efficient your resonator is. As a 14-mm long loop of conductor, the antenna was considerably larger than an on-chip inductor for a millimeter-scale radio could be. That led to a Q that was about five times what an on-chip inductor would deliver.


Though it was a much more efficient solution, in order to meet BLE specifications, the team needed a better way to power the power oscillator. Their solution was to build an on-chip transformer into the circuit that supplies power to it. The transformer looks like two nested coils. One coil is attached to the supply voltage end of the oscillator circuit, and the other is attached to the ground side. Pumping the transformer at a frequency twice that of the power amplifier wound up efficiently boosting the flow of power to the antenna, says Wentzloff.


The new transmitter was tested by broadcasting the BLE “advertising” packet—a set of bits that tell receiving devices that the transmitter is out there. “If you wanted to make a millimeter-scale tracker device, this is all you’d need,” says Wentzloff. But the advertising packet also has a payload section of up to 31 bytes, which is perfect for packing with sensor data.


The research was part of the University of Michigan’s M3 project, which is developing modular, millimeter-scale sensors. The next step, says Wentzloff, is integrating the BLE radio into one of these sensors. “We have multiple radios we use in the M3 project,” he says. “BLE would be another option in that modular platform.”


Hun-Seok Kim receives DARPA Young Faculty Award to advance research in IoT networks

Hun-Seok Kim, assistant professor of Electrical and Computer Engineering, has been awarded a 2018 Young Faculty Award from the Defense Advanced Research Projects Agency (DARPA) for his research project “Hyper‐Dimensional Modulation for Robust Low‐Latency Low‐Power IoT Networks.”


His research is expected to impact the future design and wireless operation of the next generation of Internet of Things (IoT) devices, which includes intelligent control of devices such as drones and self-driving cars.


Specifically, Prof. Kim’s project investigates a new innovative waveform; hyper‐dimensional modulation (HDM) for ultra-reliable low-latency communications (URLLC) in highly contested and austere channels.


URLLC is a new service category defined by the International Telecommunication Union that has been enabled in 5G (fifth-generation wireless). It is critical for power- and complexity-constrained military, industrial, and consumer applications in a future world containing a trillion IoT devices, which technology experts expect to see by 2035.


Kim is proposing a new class of practical modulation called hyper‐dimensional modulation HDM for use in URLLC applications. Existing solutions typically use orthogonal modulation and conventional error correction schemes, which impose significant overhead on ultra‐low power IoT devices. HDM, on the other hand, eliminates the need for explicit error correction coding, and allows a unified hardware / software architecture shared between the HDM modem, linear signal transform, and deep neural network kernels commonly required in forthcoming intelligent IoT devices, explained Kim.


Successful demonstration of HDM will fundamentally change the paradigm of designing and operating wireless IoT devices.


Kim’s research focuses on system analysis, novel algorithms, and efficient VLSI architectures for low-power/high-performance wireless communication, signal processing, computer vision, and machine learning systems.


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