Ultra-Low-Power Wireless Systems: Energy-Efficient Radios for the Internet of Things

An ultra-low-power wireless system is one which has to operate for an extended period of time with only a limited power source available, and is typically constrained to a limited size (if size is not a limitation then a larger battery could be used). Clearly the term ?ultra-low-power wireless? covers a broad range of applications which may have different key drivers as illustrated in Figure 1. For a fitness device such as a heart rate monitor, the number one driver is often cost as these are basic consumer products. For a bio-implant such as a smart pacemaker, battery life is critical as battery replacement typically requires surgery. For a smart home system such as automatic climate control, cost and battery life are important but the system also needs to support a relatively large number of devices and the communication range should be large?throughout the whole building. Finally for a gaming application such as a wireless headset, high data rate and very low latency are key, so as not to ruin the high-speed gaming experience. To minimize operating power and achieve maximum battery lifetime, the implementation of an ultra-lowpower wireless system requires an integrated design approach that considers many requirements including battery source, active and sleep mode energy requirements, system architectures, and circuit implementations. In practice, these issues lead to trade-offs, which may require numerous iterations to arrive at an optimal solution for the desired application. With the recent explosion of interest in ultra-low-power wireless systems for the Internet of Things and wearable devices, the current rate of innovation in the development of ultra-low-power wireless systems is sure to continue.