Meaning
Radio communication technologies designed to transmit small amounts of data over moderate distances while consuming minimal energy permit the operation of remote devices from small batteries or energy harvesters. Utilizing low power wireless protocols allows sensor nodes to run for years on a single coin-cell battery or a small lithium cell. This efficiency is achieved by keeping the radio in a deep sleep state for the vast majority of its operational life.
Design Tradeoffs
Achieving low power wireless performance requires a careful balance between transmission range and battery lifetime. Protocols such as Bluetooth Low Energy, Zigbee and LoRaWAN use different techniques like spread spectrum or duty-cycling to optimize this balance. For example, reducing the transmit power saves energy but reduces the maximum communication distance and increases the susceptibility to physical obstacles.
Engineering teams must analyze these trade-offs during the early stages of product development to choose the right technology for their application.
Hardware Integration
Co-designing the antenna and the board layout is necessary to ensure that the transmitted energy is not wasted as heat or reflected back into the radio. Proper impedance matching minimizes the power required to achieve a stable connection, directly extending the operating life of the device. Additionally, the selection of the low-dropout regulator and the battery chemistry can affect the peak current available to the radio during transmission.
A poorly designed power supply can cause voltage drops that reset the microcontroller during radio events.
Certification Hurdle
Products using these radios must undergo rigorous testing to ensure they do not exceed regulatory emission limits. This testing is done at accredited laboratories before the product can be cleared for commercial sale.
