We're keeping a close eye on the development of NB-IoT technologies this year. Here's where we are in 2019.
First, what is NB-IoT?
Narrowband IoT, or NB-Iot, is a standards-based LPWA technology developed by the 3GPP to enable a diverse range of IoT devices and sensors
NB-IoT improves device power consumption significantly, offers great range and indoor penetration, with relative ease of deployment in existing spectrum, and on existing base station hardware.
What are the differences between LTE CAT M1 and NB-IoT?
Both are cellular standards, but they are being adopted and rolled out quite differently (see Deployment Status below). Technically, M1 offers a noticeably higher bandwidth, which means a faster connection. Compared to NB-IoT, M1 has less range, less indoor penetration, and is less power-friendly.
Let's discuss some of these NB-IoT benefits, and a few draw backs that aren't often mentioned.
Backing of GSMA and Cellular Networks
We're often asked a basic question: how do you choose between Sigfox, LoRaWAN, or CAT M1/NB-IoT?
The friendly answer is that each has a use case, and each serves different markets.
The real answer is far more harsh - we expect the mass market to use cellular networks because they have far greater reach and resources compared to Sigfox and LoRaWAN. M1/NB-IoT is likely to have greater coverage in many regions within the next 12-24 months.
Sigfox and LoRaWAN do have a head start in most markets, but we don’t expect this to last. Sigfox and LoRaWAN are lower power than the cellular options, but with that comes less flexibility for things like firmware downloads Over The Air (OTA). Time will tell, but Digital Matter is investing heavily in CAT M1/NB-IoT capability.
Deployment Status of NB-IoT
As of March 2019 we've rolled out many more CAT M1 devices compared to NB-IoT devices. The network deployments of CAT M1 by AT&T and Telstra are the main drivers of CAT M1 success so far. The networks work well and coverage is good and reliable.
NB-IoT is proving to be slower. We have connected to NB-IoT networks successfully in: South Africa (Vodacom), Australia (Telstra), Belgium (Orange), and Netherlands (T-Mobile).
No Mobility for NB-IoT
One of the major drawbacks of NB-IoT is the lack of cell mobility. An NB-IoT modem cannot maintain connections across base stations. This feature will come in a later version of the 3GPP standard, but release 13 does not support it. This means that NB-IoT is currently NOT suited for traditional vehicle tracking. Our Dart2 and G62 devices don't make sense on NB-IoT networks. CAT M1 does support cell mobility, so they work very well on those networks.
NB-IoT networks DO work well with our battery powered devices: Yabby, Oyster2, Remora2, and Falcon. When uploading, these devices open and close connections almost immediately, so cell mobility is not an issue. We have found that eDRX and PSM features do not yet lead to power savings over establishing and tearing down a connection on each upload. This is based on practical measurements, and we hope that these features will become more useful in the future.
Over The Air updates are a big win for CAT M1 and NB-IoT* over Sigfox and LoRaWAN. An NB-IoT firmware download of about 100KB can take up to 10 minutes, but it is possible! This means in-field device feature improvements, bug fixes, and settings changes.
UDP vs TCP
UDP and TCP are networking schemes for transferring data. Both schemes work over NB-IoT**, but UDP is favoured because of the reduced overhead for sending small amounts of data.
Digital Matter devices currently use a TCP protocol. It is very interesting to analyse the bytes sent over the air. To deliver a single message, say 64 bytes of GPS data, TCP can blow out to 10 times this with message overhead and retries. Digital Matter is keeping a close eye on the NB-IoT market and will optimise the data transmission when the market requires it.
* Some cellular networks may restrict data to the point where firmware updates on NB-IoT are not feasible
** The data overhead of TCP may be too large for some NB-IoT networks