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What is ULP wireless connectivity?

There is a growing demand for ultra-low power wireless connectivity as consumer seek to extend their wireless experience to compact electronic devices with tiny batteries


Wireless connectivity underpins modern society. Consumers take cell phone access for granted, Wi-Fi hotspots are common in airports and other public places, and Bluetooth wireless technology allows seamless connection between, for example, digital cameras and printers or MP3 players and headphones. Each of these technologies fits its target application perfectly. But each has different operating characteristics and, ultimately, trade-offs between range, bandwidth, power consumption, and price.


So, for example, Wi-Fi offers the wide bandwidth needed for rapid downloads of songs and movies from the Internet, but typically requires relatively high power from either a mains supply or large capacity Li-ion batteries. In contrast, Bluetooth wireless technology requires less power than Wi-Fi, and can operate from the resources of AA cells.


However, beyond Bluetooth wireless technology, there is a growing demand for wireless connectivity for compact portable electronic devices powered by even smaller batteries, such as AAA types or coin cells. For example, an elegant solution for measuring temperature, humidity or pressure in an industrial environment, or speed, cadence, and heart rate of an amateur cyclist is to link tiny wireless sensors to a central computer via a network. These sensors are tiny devices with only enough space to accommodate small batteries but where long battery life is demanded to keep down costs and lower maintenance requirements.


ULP wireless connectivity is an elegant solution for a network of sensors measuring a cyclist’s performance statistics

ULP wireless connectivity is an elegant solution for a network of sensors measuring a cyclist’s performance statistics


In another example, wireless PC peripherals such as mouse and keyboard are increasingly popular because they dispense with untidy and inconvenient cables. But consumers aren’t willing to trade the convenience of a wireless solution for the inconvenience of frequent battery changes, so long battery life is critical. This is the world of “ultra-low power” (ULP) wireless connectivity.


There is no standard engineering definition for ULP wireless connectivity, but here at Nordic we define it as an RF link that’s able to operate from a coin cell battery (such as a CR2032 or CR2025) for periods of months or even years. These coin cell batteries are compact and inexpensive, but have limited energy capacity, typically 10 times less than an AA cell.


Operating from such a modest power source for long periods is tough technical challenge. Nordic has answered this problem with its range of nRF24Lxx 2.4GHz ULP transceivers, ANT chips, and Bluetooth low energy devices.


Small quantities of data (typically a few bits) sent infrequently (for example, once every few seconds to a few times per second at most) are the typical operating characteristics of ULP wireless connectivity. Nordic’s ULP transceivers and innovative RF protocol software combine to meet these requirements while conserving energy by operating at low peak transmission and reception power, waking quickly from low power sleep modes, sending data in rapid bursts across a high bandwidth link (to minimise time in high power modes) before quickly returning to sleep. Peak currents are in the milliampere range, while average currents measure just microamperes.