Understanding CAT-M and the Role of Data Limits in IoT Connectivity

The energy consumption, maintenance, and cost of various IoT solutions depends in part on the amounts and types of data your devices need to send and receive. Here we talk about various cellular and WAN data transfer protocols to help you decide which technology is best for you.

What Is CAT-M?

CAT-M, or Category M, is a Low-Power Wide-Area (LPWA) technology designed to support today’s IoT devices, even in the most challenging of environments. It is the first network built for a dedicated spectrum that is optimized for IoT, allowing direct connection of devices to a 4G network.

CAT-M is sometimes referred to as Long Term Evolution CAT-M or LTE CAT-M1. LTE-based IoT networks can only work if they provide long battery life and low cost, support a high volume of devices, provide enhanced coverage (i.e. for better signal penetration through walls), and work  long-range over a wide spectrum.

CAT-M meets these requirements since it was designed to operate on a lower spectrum (1.4 MHz as compared to 20 MHz as usually seen with CAT-0) with a high transmit power (20Bm). It also provides upload speeds of between 200kbps and 400kbps, supports basic mobile applications including voice connectivity, and has higher throughput with lower latency and battery consumption. It is also designed to provide an extended battery life of 10 years or more.

How Cellular IoT Originated

The rise in popularity of IoT devices has been partly due to the rise of low-power, wide-area network options such as SigFox, LoRa, and Weightless. Conventional cellular options such as 4G and LTE networks consume too much power and do not work with many applications, so alternatives that work in settings that require an infrequent transmission of data in small amounts, such as in smart metering applications, were needed. This provided the impetus for the design and deployment of cellular IoT solutions and their related infrastructure.


CAT-M1 is currently the only cellular IoT option available and it represents an early push towards connecting IoT devices using existing LTE networks. While it trails 3G networks in terms of performance and quality, it is a better option for IoT applications that require a browser interface or voice data transmission. The major pull behind it is that it is already standardized, and more importantly, it is easy to transition to the CAT-1 network. Experts predict that as 3G and 4G technologies sunset, CAT-1 and CAT-M1 networks will be here to stay.


As mentioned above, LTE-based networks can only work if they can cost-effectively support many devices with better coverage across long distances with minimal maintenance. CAT-0 provides a cost-effective solution for these requirements as it eliminates features requiring high data transmission, unlike CAT-1 which uses a dual receiver chain and a duplex filter. In simpler terms, if CAT-1 is poised to replace 3G, CAT-0 sets the groundwork for CAT-M replacing 2G as the solution of choice.

Market Perception of CAT-M

CAT-M is generally viewed as the second generation of LTE chips built for IoT applications. It is more cost-effective than the alternatives thanks to reduced power consumption, a benefit initially introduced by CAT-0. By capping system bandwidth at 1.4 MHz, CAT-M specifically targets LPWAN applications like smart metering, in which only a relatively small amount of data transfer is required.

The real advantage of CAT-M over other options, however, lies in the fact that it works with the existing LTE network. This makes it a great choice for carriers who want to avoid the cost of building new antennas. Running CAT-M on existing LTE networks requires a simple software patch; all you have to do is send an over-the-air (OTA) software update to the devices operating on the network. Companies like Verizon and AT&T would prefer this option to the construction of new infrastructure to support a new protocol. In addition, it is highly likely for 5G and LTE technologies to coexist well into the 2020s, so the backward-compatibility of these technologies with CAT-M is a bonus.


NB-IoT (also called CAT-M2) was designed with similar goals to those of CAT-M, but instead of using LTE’s radio solution, it uses DSSS (direct-sequence spread spectrum) modulation to reduce signal interference. NB-IoT does not operate on the LTE band, so providers face higher upfront and deployment costs to run on it.

Regardless, NB-IoT is being promoted as a potentially less expensive alternative to CAT-M because it does not require a gateway to work. Other infrastructures typically have portals that aggregate sensor data and then transmit that data to a primary server. With NB-IoT, however, sensor data is sent directly to the central server. For this reason, companies such as Huawei, Ericsson, Qualcomm, and Vodafone are actively investing in commercial applications of NB-IoT.


EC-GSM is an IoT-optimized GSM network. It is a wireless protocol used by about 80% of all smartphones globally. As the name suggests, it can be deployed on existing GSM networks, giving it a considerable advantage in terms of practicality and modularity since a simple software update provides connectivity of EC-GSM on 2G, 3G, and 4G networks. EC-GSM also has specific use-cases in non-Western regions such as South East Asia, Africa, and many Middle Eastern countries in which 2G is commonly used. Ericsson, Intel, and Orange are believed to have completed live trials of EC-GSM in early 2018. However, EC-GSM has not generated as much press coverage as some of the alternatives in this space.


5G is yet to be officially defined, unlike the cellular IoT solutions discussed above. The NGMN (Next Generation Mobile Networks) Alliance is pushing for it to be 40 times faster than 4G while supporting up to 1 million connections per square kilometer. 5G is likely to enable high-bandwidth, high-speed applications for Ultra-HD (4k) streaming, self-driving car connectivity, and VR/AR applications. Large wireless carriers like Verizon and T-Mobile have begun rolling out 5G connectivity in select locations, though its coverage remains limited.

Which LPWAN Is Best for Me?

Different cellular IoT options do not have to be mutually exclusive. The leading LPWA technologies include NB-IoT, which is focused on low data rates and is ideal for straightforward static sensor applications, but LTE-M (CAT-M) provides the lightest bandwidth of any LPWA technology and is suitable for fixed and mobile applications – both of which are 5G-ready. The solution you choose depends on your requirements, the connectivity specs your business needs, and the existing infrastructure wherever you operate.

Kajeet Solutions Engineers can help you set up an IoT infrastructure that works for you based on your data needs and budget. Contact us today for a consultation with one of our tech experts, or click here to learn more about private wireless networks.

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