The mature IoT will see Local Area Network (LAN) technologies such as Bluetooth Low Energy (Bluetooth LE) and Thread, and Low Power Wide Area Networks (LPWAN) based on cellular IoT working in harmony.
One scenario illustrating this synergy imagines dozens of mesh-connected Bluetooth LE or Thread nodes embedded in smart lights illuminating a parking lot. The nodes will monitor their surroundings and then transmit information about traffic density, power consumption, and the temperature of the LEDs (which affects their life span) to one or more cellular IoT modems.
In turn, the modems will aggregate the data and forward to the Cloud via the cellular network - enabling a remote parking lot manager to decide where lights can be dimmed because no one is around, and which need servicing during the next maintenance round.
However, while Bluetooth LE or Thread LANs and LPWANs based on cellular IoT will technically play nicely together, different data-usage models will apply. This in turn impacts the choice of cellular IoT technology.
Specifically, data sent across a Bluetooth LE mesh is free (discounting the cost of the energy required to transmit the packets), while that sent using modems wirelessly connected to a cellular network will be metered and subject to carrier fees.
Information not data
When data is metered, it becomes very important to optimize transmission efficiency. It’s one thing for a consumer to foot the occasional bill for streaming Netflix videos to their smartphone, but quite another for the parking lot company to continually pay charges for dozens or even hundreds of cellular IoT nodes sending data about smart lights 24 hours
a day.
The solution is to ensure the cellular IoT modem is smart enough to send valuable information rather than kilobytes of trivial raw data. For example, when considering the parking lot lighting example, most of the time most of the lights will be working well. There seems little point constantly reporting that fact. Rather, the raw data from the Bluetooth LE LAN sensors could be buffered and then analyzed by the cellular modem for exceptions to normal performance.
For example, if the modem receives a signal from light “41B” indicating that the LEDs are running 20OC over normal operating temperature, it would be useful for the device to compute that the elevated temperature will cause LED failure within 72 hours and then pass that information to the parking lot owner.
Such information is valuable because the light can then be fixed before failure, preventing costly situations such as motorists colliding in the dark and then seeking damages via an insurance claim against the lot owner.
In a second example, the parking lot manager might want information about the power consumption of the lights — even if they are all working normally — to estimate the size of his or her electricity bill.
Instead of constantly sending raw data about each light’s instantaneous power consumption, a smart cellular modem could, for example, buffer the data, compute the power consumption for a 24-hour period, and then send that information in one short burst across the cellular network
– again limiting data charges.
Integrated development
Like their Bluetooth LE and Thread counterparts, LTE-M (for M2M) and Narrow Band-IoT (NB-IoT) modems will include microprocessors to look after the RF communications and run application-specific software.
Moreover, in order to facilitate development of intelligent software to run on end-devices, it is crucial the modems are supported by a good software framework and development environment. The application development platform needs to be tightly integrated with the modem
and its functionality to enable the modem to work in concert with the application to reduce energy consumption while maintaining the required performance.
Expect to see new LTE-M and NB-IoT products leveraging such technology, to meet the power consumption/computational performance trade-off while meeting the demands of the subscription usage model adopted by cellular carriers.
Nordic is a leader in Bluetooth LE and embraces Thread with its nRF52 Series Systems-on-Chip (SoCs) and is now applying its RF and ultra low power expertise to its forthcoming nRF91 Series cellular IoT products.
The nRF91 Series is based on the 3rd Generation Partnership Project’s (3GPP) LTE-M and NB-IoT specifications and will allow Nordic to offer customers a seamless LAN/LPWAN wireless IoT solution. Nordic is backing cellular IoT because of the clear advantages it brings over competing proprietary technologies.