Quick Hits

Cellular Technology

When you consider how to connect your IoT solution to the Internet, often cellular is a viable option. But what is Cat-3 or Cat-1 or HSPA+? Where do these cellular technologies operate? Is it fast enough for your application? Can it be cost effective?


When you consider how to connect your IoT solution to the Internet, often cellular is a viable option.  But what is Cat-3 or Cat-1 or HSPA+?  Where do these cellular technologies operate?  Is it fast enough for your application?  Can it be cost effective?

In this Quick Hits video, you’ll learn what cellular options are available for Systech gateways, and how you can choose the cellular option that is best for your application. 

So check this out!

-- Intro --

Hello, I’m Robert Lutz with Systech Corporation.

As you begin to look at cellular options for an IoT gateway, it can quickly get confusing.  It is unbelievable how quickly new communication technologies are being introduced by the cellular carriers around the world.

We have all lived through the transitions from analog cellular, 2G, 3G, and more. 

Given the rapid pace of cellular evolutions, you might wonder if cellular is an option your IoT application can rely on.  Especially if your application is deployed for 5 years, or 10 years, or more. 

At Systech, we completely understand your concerns.  We have deployed over a million gateways over the years, and some of our gateways are still in the field after 10-plus years of service.  For example, inside ATMs or tank monitoring applications.

So, let’s review the current state of cellular data options for IoT applications.

Most cellular technology is based on specifications managed by the 3GPP organization, or the 3rd Generation Partnership Project.  3GPP manages cellular standards such as 2G, 3G, 4G, and the future 5G standards.  These standards evolved from GSM technology from the 2G cellular era.  In the United States, AT&T and T-Mobile are carriers that use 3GPP standards for 3G.

A different organization manages specifications based on another 3G technology known as CDMA2000.  In the United States, Verizon and Sprint are carriers that use CDMA2000, at least for their 3G and earlier technology. 

All common carriers use 3GPP standards for 4G.

In the environment of 3GPP, the current version of the standard is Release 13, and includes various categories of technology.  This is where the “Cat” comes from when describing the specific cellular technology, such as “Cat-1” or “Cat-3”.

So, let’s go through the most common technologies available today.

I am going to skip over the 5G cellular technology, as 5G is still under development, and will not be deployed in the near-term.

Also, I am going to talk about theoretical data rates. Actual real world data rates are often half the theoretical limits, or worse. So take these data rates with a grain of salt.

Starting with 3G technology, HSPA+ is the most commonly deployed cellular technology both in the US, and internationally.  HSPA+ is based on earlier GSM technology, and is managed by the 3GPP organization.  The maximum data rate varies worldwide, but is usually between 2 to 22 Mb/s.  This is about a 10-fold speed increase from the older 2G technology, which has largely become obsolete.  3G cellular modem hardware is moderately expensive, about twice that of 2G.

In the US, and some other regions, a few cellular carriers implement a different technology for 3G, which is CDMA.  CDMA is part of the CDMA2000 specification, and is managed by a different group than 3GPP.  In the United States, Verizon and Sprint are carriers that use CDMA2000 standards.  CDMA performance is similar to HSPA+ speed, or perhaps a bit slower.

Probably the largest issue with the use of 3G technology is that its obsolescence is on the horizon, just like its 2G predecessor.  This is especially true in the US, where some carriers are no longer approving new products for certification on the 3G network.

As we move beyond 3G, the most common cellular technology used today is often referred to as 4G LTE, or just LTE for Long Term Evolution.  The 3GPP standard defines several categories of LTE.

The first commonly used LTE technology was Cat-3.  But this has been upgraded by most carriers today with Cat-4.  The top download data rate of Cat-3 is 100Mbs.  Cat-4 increased that to 150Mbs.  Realize that this is the theoretical maximum rate, and is often slower.

Most IoT applications do not require the high data rates supported by LTE Cat-3 or Cat-4.  And, in fact, the hardware required to support the fast data speeds is relatively expensive, almost twice as expensive as 3G hardware.

So newer, LTE categories were created that use the same underlying technology of 4G LTE, but require less hardware, optimize radio usage, and operate at lower data rates.  Let’s review these slower and less expensive LTE categories.

LTE Cat-1 requires hardware that is less expensive than Cat-3 or Cat-4 hardware.  But the maximum data rate is 10Mbs, or an order of magnitude slower than Cat-3.  Cat-1 speed is fairly similar to the older 3G technology.

But, a significant feature is that Cat-1 technology uses the same radio technology and spectrum as other LTE technology, so it is simple for carriers to support Cat-1 simultaneously with all other LTE.  Additional cost savings are available if a single antenna is used with Cat-1, rather than the recommended two antennas.

More recently Cat-M1 was introduced.  Its maximum data rate is 1Mbps, which is another order of magnitude slower than Cat-1.  This speed is similar to the older 2G technology.  For many IoT applications, Cat-M1 speed is plenty fast enough. 

Cat-M1 hardware is less expensive than Cat-1, almost approaching the cost of Wi-Fi or Bluetooth radio technology.  Again, Cat-M1 piggybacks on cellular LTE radio technology, so carriers need no additional hardware radios to support Cat-M1.

Additionally, Cat-M1 requires only a single antenna, rather than two antennas, for further cost savings.

Today, as I record this, both Verizon and AT&T have deployed both Cat-1 and Cat-M1 nationwide in the US.

Internationally, another low-cost, low-speed cellular technology is being deployed.  This is NB-IOT.  NB-IOT hardware cost is similar to Cat-M1 – perhaps a bit less expensive.  Its maximum data rate is 250Kbps, or a quarter of Cat-M1.  However, it is only a half-duplex technology, which limits performance further for some applications.

But most significantly, NB-IOT does not piggy-back on existing LTE carrier technology, so it requires additional hardware changes at the cell tower.  This has slowed down NB-IOT deployment, especially in the US.  Deployment internationally is stronger.

Here is a summary of the cellular technologies I covered in this Quick Hits video.  There is also a link to access this table directly. 

The cellular technology landscape is constantly changing.  I will attempt to keep the online version of this table up-to-date as things change.

With all the constant changes in cellular technology, you might wonder how you can deploy a cellular solution for the long term.  At Systech, we have developed a solution to help protect your cellular IoT investment.  Systech implements an industry standard cellular modem option card system using mini-PCI Express.  This modular solution allows you to easily swap in newer cellular technology – even in units previously deployed in the field.  Your hardware investment remains safe, without the need to replace your inventory of deployed gateways as cellular technology evolves.

I hope this short, Quick Hits video helped you and your IoT application.

This is just one of many Quick Hits topics available at Systech.com. Take a look at other Quick Hits Topics, and I am sure you will see one that you’ll find valuable.

Thanks, and have a great day.

Cellular Technology Summary

2G 3G LTE Cat-3 LTE Cat-4 LTE Cat-1 LTE Cat-M1 NB-IoT
Download Speed 0.1
EVDO: 2-3 Mbps
HSPA+: 7-21 Mbps
100 Mbps
Upload Speed 0.02
Antennas 1 2 2 2 2 1 1
Duplex Full Full Full Full Full Full Half
Modem HW Complexity 40% 75% 100% 100% 80% 20% 15%

Cellular Frequency Bands

Operator Frequency (MHz) Band
AT&T 700b,c 17
850 5
1700 4
1900 2
2300 30
Sprint 850 26
1900g 25
2500 41
T-Mobile 600 71
700a 12
1700d,e,f 4
1900 2
Verizon 700c 13
1700f 4
1900 2