IoT Blog

IoT Blog

What is LPWA for the Internet of Things? Part 3: A Guide to Decoding the Technologies

by Gus Vos, Chief Engineer, Technology Standards

In my last posts in this series, I wrote about how Low Power Wide Area (LPWA) technologies are addressing the critical three C’s for the IoT, and the benefits of standard versus proprietary technologies.

With the 3GPP recently ratifying NB-IOT category-NB1 in June, it’s a good time to breakdown the three 3GPP LPWA technologies (CAT-M1, CAT-NB1, and EC-GSM-IOT) and the intended use cases for each.

Standardized LPWA technologies from 3GPP, come from the same proven and trusted mobile cellular technologies used in smartphones, with specific advancements designed for the IoT (the three C’s). They have greatly improved coverage that allows deep indoor usage (even in basements) and are extremely power efficient so that IoT devices can run and communicate on batteries for up to 15 years.

The 3GPP has specified three flavors of LPWA technologies to run on licensed bands:
  • LTE-MTC (sometimes shortened as LTE-M), an evolution of the 4G LTE technology with the first defined subcategory being “Category-M1” or Cat-M1
  • NB-IOT, a narrower adaptation of the 4G LTE technology designed to fit into 2G channels, with the first defined subcategory being “Category-NB1” or Cat-NB1
  • EC-GSM-IOT (usually shortened to EC-GSM), a 2G evolution of the GSM technology very well suited in countries with a strong existing 2G coverage

banner-blog-coverage analysis LTE-M

Why did the 3GPP define three different technologies? The simple answer is that every geographic region has a different mix of 2G and 4G LTE network infrastructure deployed and, since all three of these LPWA technologies leverage the existing network infrastructure (i.e. can be deployed by software upgrade to the base stations), different LPWA technologies are needed.

  • Category-M1 is most likely to be used where LTE coverage is strong, e.g. in North America, Japan, and Australia, and it is ideal for applications requiring voice, mobility, and slighting higher throughput.
  • Category-NB1 is primarily an LTE technology but has the ability to re-farm some 2G spectrum, so it is likely to be deployed in areas where some LTE is available and recycling GSM spectrum is acceptable, e.g. in Europe and China. Cat-NB1 is idea for simpler sensor applications requiring very low throughput. 
  • EC-GSM-IOT is a 2G technology and likely to be strong in countries that are committed to keeping their 2G networks up for many years and/or where 4G coverage is insufficient, including Europe, China, India, Malaysia, Russia, Africa, Middle East, South and Central America, and Mexico.
Cheat Sheet for Standard LPWA Technologies
Attribute
CAT-M1 
(LTE-M)
CAT-NB1 
(NB-IOT)
EC-GSM
Spectrum
LTE Bands
LTE and Farmed 2G Bands
2G Bands
MNO Infrastructure
Good LTE Coverage
Mix of LTE and 2G Coverage
Long Term Commitment to 2G
Device Bandwidth
1.08MHz
180KHz
200KHz
Network Rollout
Software Upgrade
Software Upgrade
Mostly Software Upgrade
Strong Regional Fit
Australia, Japan, North America
China, Europe
Africa, India, Latin America, Russia

Selecting which technology to choose might be as simple as selecting the technology that is available in the geographic area where you want to deploy. And to make it even easier, Sierra Wireless will support multiple LPWA technologies on the same module for companies wanting to deploy their solutions on different LPWA cellular networks worldwide using the same hardware.

In the more distant future, some areas may support more than one 3GPP LPWA technology, and there are some capability differences to note. The data rates are different and the ability to support voice is not available on some. So think through both near- and long-term application requirements before selecting an LPWA technology. For example, it was commonly thought that IoT would never need voice, but it’s now a growing requirement for many IoT applications, including vehicles, wearables, elevators and healthcare applications, to name a few. The next invented killer IoT application may very well need real-time communications.

Cheat Sheet for Standard LPWA Technologies
Attribute
CAT-M1 
(LTE-M)
CAT-NB1 
(NB-IOT)
EC-GSM
Voice Capability
Yes
No Yes
Mobility
Full
Partial
Full
Data Rate
375 kbps
20-65 kbps
70 kbps
Latency
Fast (~same as LTE)
Medium
Slow
Communication: IP vs 
Simple Messaging
Depends on MNO Deployment

The good news is that most chipsets and module vendors will be able to support more than one 3GPP LPWA technology, so the choice will really come down to the feature requirements of your application.

Choosing the right 3GPP LPWA is not like a VHS vs Beta or Wi-MAX vs LTE, we expect all three technologies to be wildly successful! 

Watch for my next posts on LPWA, which will look at practical applications for the technology in Smart Cities and water management.