What is the difference between NB-IoT and LTE-M?
Neil Carter
Managing Director of Award Winning - Electronic Design & Software Development Consultancy With a Heart
Finally the United Kingdoms Telecom operators has started to embrace IoT with the introduction of NB-IoT and LTE-M ( sometimes referred to at Cat-M1)
Vodaphone have rolled out NB-IoT almost nation wide according to coverage maps and Telefonica O2 are close behind with LTE-M so I thought it might be useful to explain the difference between the two when it come to use with IoT
Both technologies are 3GPP standardised technologies designed to support a massive IoT strategy which is the deployment of a huge amount of low-complexity devices that do not need to communicate with high frequency. High Performance and low transmission latency are not a requirement. The two technologies are complimentary to each other and address different use cases based on the strength of the capabilities of the two technologies.
They do however both have some common use cases
LTE-M and NB-IoT technologies both provide low bandwidth cellular communication but there are important differences to decide when choosing the right cellular protocol for your industrial IoT or Wearable applications.
NB-IoT
It supports very narrow bandwidth, 200 kHz, So the data rate peaks at around 250 Kbps. Also, it can be deployed even in guard-band of an LTE carrier to use the spectrum that is otherwise unused.
Costs less: NB-IoT uses half-duplex communications, which means either the module is transmitting data or the cellular base station is transmitting data – not both. This use of half-duplex communications -- combined with NB-IoT’s lower data speeds and its use of lower Radio Frequency (RF) bandwidth and a single antenna -- reduce the complexity and thus cost of NB-IoT devices by as much as 50 percent compared to regular LTE-M cellular modules.
Consumes less power: NB-IoT reduces the power consumed by battery-powered modules when they transmit data by up to 75 percent compared to regular LTE-M modules, thanks to features like Power Savings Mode (PSM) and eDRX (Extended Discontinuous Reception), as well as NB-IoT’s ability to optimize the amount of energy used for small data transmissions. This allows IoT application developers to build devices that can operate for a decade or more using battery power.
Provides more capacity: NB-IoT’s use of narrowband transmission, signaling optimization, adaptive modulation, and hybrid automatic repeat request (HARQ) enables as many as one million NB-IoT devices per square kilometer to connect to the network.
Delivers better coverage: NB-IoT employs large signal repetition. While this lowers NB-IoT’s data rate, and increases its power consumption, large signal repetition improves NB-IoT’s coverage by 5-10X over other cellular technologies. Thanks to this better coverage, NB-IoT devices can connect to cellular networks even if they are located deep inside a building, in a remote rural location, or even underground.
LTE-M
LTE-M is considered as the second generation of LTE chips created for IoT applications. It provides low-cost LTE devices suitable for Massive Machine-Type Communications (MTC) and the Internet of Things (IoT) with enhanced coverage compared to normal LTE devices.
Recommended by LinkedIn
There are three main features to focus on when talking about LTE-M:
It operates at 1.4 MHz bandwidth with higher device complexity/cost than NB-IoT. The more bandwidth allows Cat-M1 to achieve data rates (up to 1 Mbps), lower latency and more accurate positioning capabilities. LTE-M supports voice calls and connected mode mobility.
LTE-M provides faster data rates than NB-IoT, as well as lower latency (the amount of time it takes for a device to connect to a network and send or receive a message). These capabilities allow LTE-M to support voice communications in addition to data communications, as well as IoT applications (like precision tracking or power grid control) that need more real-time communications. In addition, LTE-M provides much better performance for mobile IoT applications than NB-IoT, despite the mobility upgrades found in Cat-NB2.
LTE-M's faster speeds also make it better for more data-intensive IoT applications. Additionally, LTE-M, as a natural extension of 4G LTE, benefits from out-of-the box roaming, i.e. the ability to use a SIM card from a network operator on another operator’s network abroad.
NB-IOT Vs. LTE-M
The Similarities between NB-IoT and Cat-M1 capabilities
Both NB-IoT and Cat-M1 devices can sleep for extended periods of time with extended Discontinuous Reception (eDRX) and Power Saving Mode (PSM) functionalities, which greatly reduces device power consumption. Furthermore, both technologies support enhanced signal coverage per base station.
Which is better, NB-IoT or LTE-M?
Given that LTE-M is more powerful than NB-IoT, that doesn’t mean it’s better. It’s based on the use case, As an example from an operator perspective, NB-IoT can create more deployment flexibility due to guard-band deployment. If the operator’s available frequency assets allow, NB-IoT can also be deployed as stand-alone access.
On the other hand, for IoT applications requiring higher data rates, low latency, full mobility, and voice in typical coverage situations, LTE-M is the best LPWA technology choice.
However, NB-IoT does have some advantages over LTE-M. Though both LTE-M and NB-IoT provide better coverage than other technologies, most network operators have deployed NB-IoT networks with technologies that deliver the best possible coverage improvements, and LTE-M networks with technologies that provide only partial coverage improvements. In the real-world today, this leads to NB-IoT networks providing better coverage than LTE-M in warehouses, office buildings, and underground locations where signal loss and multiple layers of obstruction can lead to connectivity problems.