As the use of IoT devices continues to proliferate at an astounding rate so have connectivity options designed to support their use.
The number of IoT connected devices will reach a whopping 75 billion according to a recent analysis by Morgan Stanley. In recent months the number of technology solutions designed for IoT connectivity options using Cat-M1 and NB-IoT has been on the rise.
While both are technologies well-suited for IoT sensor and device connectivity in smart buildings, they address different types of use cases based on their capabilities.
What is Cat-M1/Cat-M/LTE-M?
Cat-M1, known as LTE Cat-M1, operates at 1.4 megahertz bandwidth and supports higher device complexity. Cat-M1’s wider bandwidth allows it to achieve greater data rates, lower latency and more accurate device positioning.
Cat-M1 also supports voice and mobility and has specific use cases for LPWAN applications like smart metering, in which only a small amount of data transfer is required.
Cat-M1 is compatible with the existing LTE network which makes it attractive to carriers like Verizon and AT&T. Adding Cat-M into LTE networks requires a software update.
What is NB-IoT/Cat-M2?
NB-IoT, narrow-band IoT, supports ultra-low complexity devices with a very narrow bandwidth of 200 kilohertz and data rate peaks of about 250 Kbps.
NB-IoT is best suited for very low data rate applications in extremely challenging radio conditions and its most common use cases include utility meters and smart building sensors which often do not require massive data transmissions capabilities.
NB-IoT is considered a less expensive option because it eliminates the need for gateways to aggregate sensor data and communicates directly with the primary server.
Huawei, Ericsson, Qualcomm, and Vodafone are actively investing in commercial applications of NB-IoT.
NB-IoT versus Cat-M1
Both options link low powered battery operated sensors and devices used in smart building sensors, utility metering devices, wearables and trackers.
NB-IoT and Cat-M1 can both sleep for extended periods of time and operate in discontinuous reception and power saving mode functionalities which greatly reduce power consumption on battery-operated devices which is critical.
Cat-M1 and NB-IoT also both support enhanced signal coverage per base station.
Compared to NB‑IoT, LTE Cat M1 is ideal for mobile use cases, because it handles hand‑over between cell towers much like high-speed LTE.
For example, if a vehicle moves from point A to point B crossing several different network cells, a Cat M1 device would behave the same as a cellular phone and never drop the connection.
An NB‑IoT device, on the contrary, would have to re‑establish a new connection at some point after a new network cell is reached. For this reason, Cat-M1 is better suited to applications where sensors are placed on moving devices or require higher data transmission rates with no interruptions.
While these superior capabilities make Cat-M1 more expensive when compared to NB-IoT they may not be required in many smart building use cases.
For example, using a sensor to check boiler systems located in the basement would better be suited for NB-IoT, however, to track an elevator which goes down to the basement Cat-M1 would be the better connectivity option because it’s a moving object.
While NB-IoT and Cat-M1 each have unique capabilities, they are not mutually exclusive and are often used together.