Specifications of a Cellular Modem
Inside every cellular device is a component known as a cellular modem, and the specifications and capabilities of that modem can make an absolutely huge difference in your mobile internet experience.
Cellular technology is the most common way for RVers and Cruisers to get online - whether utilizing a smartphone, a mobile hotspot (aka Jetpacks or MiFis), or a full-on cellular-embedded router.
However, not all cellular devices are created equal.
As each cellular carrier continues to evolve and advance its networks, your cellular data performance will be directly impacted by the specifications of your modem is to fully take advantage of the cellular network it is connected to.
The performance difference between a modern high-end modem and an older basic modem can be as dramatic as the performance difference between a Ferrari and a Go Cart. Just knowing you have "3G," "4G," or "5G" is not nearly enough.
Understanding how to interpret cellular modem specifications is critically important since newly released cellular devices surprisingly often still contain older and slower modems. You need to know what you are shopping for to make informed purchasing decisions.
In other words - it really helps to understand what is under the hood of a cellular modem to better compare the specfiications and know what sort of performance to expect.
For those who consider mobile internet critical to their lifestyle, we recommend evaluating your cellular gear (and the modems inside!) at least every year or two to ensure that you keep current.
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Cellular Modem Specifications Video Overview
This video companion to this article goes over the cellular modem specifications and explains why not all modems are created equal:
What is a Modem?
The word "modem" was originally short for modulator/demodulator - and back during the earliest days of the internet, dial-up modems connected the digital world of computers to the audio world of telephone lines, turning data into sound and back again.
A cellular modem is doing basically the same thing - translating between the digital world inside your smartphone, hotspot, or router and the analog world of radio broadcasts over the cellular antennas.
But technology has come a long way since the days of 300bps dialup.
Modern 5G cellular modems can transmit and receive on up to five (or more!) radio channels simultaneously and using four antennas simultaneously, all while processing gigabits of data per second.
It is pretty amazing to think how far cellular technology has come in just the past decade - and the technology continues to evolve extremely rapidly.
So, what makes one cellular modem so much different than another? It all comes down to the technology inside, which are defined by a cellular modem's specifications.
Things to consider:
- The modem's technical generation, performance category, and peak theoretical speed.
- The frequency bands supported.
- How many channels on those frequency bands can the modem combine and take advantage of simultaneously.
- How many antennas can the modem can utilize.
We'll briefly cover each of those areas here and go even deeper in cellular modem specifications in the members-only area.
Cellular Modem Generations & Performance Categories
The first critical cellular modem specification to understand is a modem's generation and performance category.
The 3GPP (Third Generation Partnership Project) is the international industry consortium that defines cellular standards for 3G, 4G/LTE, and 5G.
Cellular modem performance and capabilities depend, in large part, on which version of the standards a modem is designed to support.
Roughly every decade a new generational standard is released that breaks from the past to enable substantial new capabilities, but even within a given generation smaller but still significant releases push the standards forward.
Here are the major standards behind the best-known cellular technology eras, some sample modem performance categories (and peak theoretical performance ratings) from each generation, and the year the standard was finalized:
- LTE - 3GPP Release 8 (2008)
- Category 3 - 100 Mbps down / 50 Mbps up
- Category 4 - 150 Mbps down / 50 Mbps up
- LTE-Advanced - 3GPP Release 10 (2011)
- Category 6 - 300 Mbps down (2x carrier aggregation) / 50 Mbps up
- Category 7 - 300 Mbps down (2x carrier aggregation) / 100 Mbps up (2x upload carrier aggregation)
- Category 12 - 600 Mbps down (3x carrier aggregation) / 100 Mbps up (2x upload carrier aggregation)
- LTE-Advanced Pro - 3GPP Release 13 (2016)
- Category 18 - 1.2 Gbps down (5x carrier aggregation) / 150 Mbps up (2x upload carrier aggregation)
- Category 20 - 2 Gbps down (7x carrier aggregation) / 316 Mbps up (3x upload carrier aggregation)
In the 5G era, LTE performance categories are not used, but every modem generation continues to evolve in the amount of data and spectrum that can be processed simultaneously. To illustrate the evolution of 5G capabilities, we compare Qualcomm modem chipsets - the industry leader - from each generation.
- 5G "Phase 1" - 3GPP Release 15 (2018)
- Qualcomm X50 - 5.0 Gbps Max Throughput / 100 MHz Sub-6GHz 5G Bandwidth (no carrier aggregation)
- Qualcomm X55 - 7.5 Gbps Max Throughput / 200 MHz Sub-6GHz 5G Bandwidth (limited 2x 5G carrier aggregation)
- Qualcomm X60 - 7.5 Gbps Max Throughput / 200 MHz Sub-6GHz 5G Bandwidth (flexible 2x 5G carrier aggregation)
- 5G "Phase 2" - 3GPP Release 16 (2020)
- X65 - 10 Gbps Max Throughput / 300 MHz Sub-6GHz 5G Bandwidth (flexible 3x 5G carrier aggregation)
- X62 - 4.4 Gbps Max Throughput / 120 MHz Sub-6GHz 5G Bandwidth (flexible 2x 5G carrier aggregation)
- X70 - 10 Gbps Max Throughput / 300 MHz Sub-6GHz 5G Bandwidth (flexible 4x 5G carrier aggregation)
- X65 - 10 Gbps Max Throughput / 300 MHz Sub-6GHz 5G Bandwidth (flexible 3x 5G carrier aggregation)
- 5G-Advanced - 3GPP Release 18 (2023)
- X75 - 10 Gbps Max Throughput / 300 MHz Sub-6GHz 5G Bandwidth (flexible 5x 5G carrier aggregation)
- X72 - 4.4 Gbps Max Throughput / 200 MHz Sub-6GHz 5G Bandwidth (flexible 3x 5G carrier aggregation)
- X75 - 10 Gbps Max Throughput / 300 MHz Sub-6GHz 5G Bandwidth (flexible 5x 5G carrier aggregation)
It takes several years from the time a standard is defined until products supporting that standard become mainstream, and sometimes even longer for the cellular networks to evolve and deploy upgraded towers to fully take advantage of the new capabilities.
But all things being equal - a cellular device that supports the newest version of the 3GPP standards will be much more future-proof and better able to take advantage of newer technologies being deployed by the carriers.
And devices based upon older standards will be increasingly left behind as time goes on.
This can be particularly frustrating for uninformed shoppers not familiar with cellular modem specifications, especially considering that new products are still being released in the 5G era based on the version of the 4G cellular standards defined in 2008.
These products might perform "OK" at first - but they are obsolete from the moment they are powered on. The differences might not be obvious at first without directly comparing cellular modem specifications to a more modern device.
As of 2024, most product categories have reached "5G Phase 2" (Release 16) of the evolution of 5G. The pace of evolution is slowing down and stabilizing a bit as 5G goes from being an emerging technology to the mainstream.
With 5G's evolution reaching a new plateau - most of the latest 5G modems on the market that support 5G Phase 2 are destined to remain reasonably future-proof for years to come.
New technologies will continue to offer improved performance and features, but the current baseline will likely still offer a relatively compelling and compatible experience, perhaps into the 2030's and the 6G era.
Theoretical Performance - Reality Check
Peak theoretical performance listed on specification sheets indicates what a given modem might be capable of under laboratory conditions with a single cell tower and device communicating with no other interfering devices within the detectable range.
Real-world performance on an actual cellular network with potentially hundreds of other devices sharing the airwaves will more typically be just a tenth (or less!) of what is theoretically possible.
The important thing to keep in mind is the relative jumps between different performance categories. For example - you will never see 300 Mbps on a Cat-4 modem, but you will often see a Cat-6 modem perform twice as fast as a Cat-4 modem under identical real-world conditions.
Frequency Bands & Carrier Compatibility
Evaluating the cellular generation is only part of the equation when comparing cellular modem specifications.
The next vitally important cellular modem specification to pay attention to the cellular bands the modem supports to ensure that it is a good fit for the carriers you intend to connect to.
These cellular bands are the invisible highways in the sky that the cell towers use to communicate - think of them like TV channels but broadcasting mobile internet. Some of these channels travel further, and others support faster speeds. A modem that can tune into as many channels as possible is very important for maximum coverage and performance.
Older cellular modem generations tend to support many fewer cellular bands than the newest releases - and in particular, bands like 71 (critical for the best coverage on T-Mobile) or 14 (AT&T's FirstNet) are often missing from older modems.
In general, higher-end and more modern modems have significantly more support for various frequency bands, and some routers even support manual band selection - allowing you to override what the tower assigns to you for even more performance tuning potential in challenging signal situations.
It pays to dive deep into the specifications to ensure you invest in gear that will remain relevant in the future.
For more on the current frequency bands each carrier utilizes:
Which Cellular Carrier is Best?
Carrier-Specific Devices
Though it is technically possible to build devices that work across multiple carriers - many mobile hotspots, internet devices, and even some phones are designed and specifically optimized for a primary carrier. Even if the modem chipset inside supports additional bands other carriers use, these bands might not be enabled in the device.
Typically, these devices tend to be offered directly by the carrier for purchase and are even branded as such.
For example, the Inseego MiFi X Pro has different versions designed for Verizon or T-Mobile that support different cellular bands. And, the Netgear Nighthawk M6 has models specifically for AT&T and an "all carrier" unlocked model.
Just because a device is branded for one carrier, that doesn't mean it won't work with others. It might!
If you do have a carrier-locked device - you'll need to jump through hoops to get your current carrier to unlock the device before you can connect to their competitors.
Additionally, many non-branded and fully unlocked devices on the market can successfully work on multiple carriers without any hassles - though you might miss out on some performance and coverage if not all bands are supported.
Higher-end cellular-embedded mobile routers, in particular, tend to support multiple carriers by default and are typically not tied to any specific one.
Flagship smartphones tend to have cross-carrier compatibility as well, but you still need to check the specific specs of the phone, as some are released with features tied specifically to a single carrier.
For more on using carrier-specific devices on other networks:
Using a Carrier Specific Cellular Device on Another Carrier
Carrier Aggregation Overview
Carrier aggregation is a core feature of modern LTE and 5G cellular modems and is critical for reliability and performance. Understanding how to interpret carrier aggregation specifications is an important part of evaluating a cellular modem.
In a nutshell, carrier aggregation allows a modem to combine multiple frequency bands to deliver faster and more reliable performance. Carrier aggregation technology is available on LTE Advanced modems (Cat-6+) and 5G.
By combining bands, your device can take better advantage of any signal it finds around you.
When Carrier Aggregation is engaged (this happens automatically behind the scenes), one band is the primary band for both upload and download connections, and additional bands are added into the connection to turbo-charge the download (and sometimes upload) speeds.
Some high-end 5G and LTE cellular modems can support up to 7-channels of 4G/LTE carrier aggregation.
A lack of carrier aggregation support is a sign of a rather basic modem.
Carrier aggregation makes a huge difference behind the scenes, but for some reason, device makers and cellular networks make it very hard to tell when carrier aggregation is actually active. Higher-end cellular routers, though, often display the bands you are connected to on their dashboards.
5G Standalone Mode & 5G Carrier Aggregation
Carrier aggregation became a key technology as 4G/LTE evolved, and it is also a very important technology in 5G's evolution. It will only become more important in time as a technology known as "5G Standalone Mode" becomes more widely deployed.
The first wave of 5G devices supports two-way 5G carrier aggregation when in Standalone mode but not across frequency ranges or broadcast signal types.
In practice, most early Phase 1 5G routers are limited to using just a single 5G band when in Standalone (SA) mode, often substantially sacrificing their performance potential.
On the other hand, 5G Phase 2 routers can stitch together all types of 5G spectrum - enabling better performance, particularly on carriers like T-Mobile, where Standalone mode has been widely deployed.
Over time, the number of 5G bands that can be combined by the latest 5G modems will only continue to advance.
What Is 5G Standalone Mode?
The first wave of 5G networks is limited because they depend on 4G networks behind the scenes for voice calls and managing the 5G connection. In fact, many 5G networks are often "download only," with all uploads still handled over the LTE portion of the connection.
This is called "non-standalone" (NSA) 5G - with 5G added as a speed layer on top of whatever combination of multiple 4G bands the modem has negotiated with the tower. The 4G connection is still the primary connection when in NSA mode.
A 5G connection that can run independently without 4G is called "Standalone" (SA) mode, and this will become more common as carriers upgrade their networks and devices to fully support this mode.
Running in fully native 5G mode will allow 5G's improved performance potential and lower network latency to really shine, and will also likely improve battery life since the LTE radio will be able to go to sleep when not needed. This requires hardware & software compatibility for both the device and the cell tower.
Combining 5G carrier aggregation and standalone 5G will allow 5G networks to deliver a truly next-generation experience.
However, many early-generation 5G devices are relatively limited in their capabilities here.
Cellular Antennas & MIMO
The next important cellular modem specification is how many antennas it utilizes. All LTE and 5G modems utilize multiple cellular antennas - usually two or four.
The more antennas, the better - so it is important to know how many antennas the modems you are considering can use.
These antennas work in unison - in weak signal areas, they help the modem isolate a single signal from the background noise.
In stronger signal areas, the antennas can work in parallel, and the tower can simultaneously send a different signal to each antenna using the same broadcast channels. This allows you to potentially double or even quadruple your speeds.
Think of it like trying to listen in on two (or four!) conversations at once - it takes concentration, but it is possible!
As technology advances, newer devices can better use MIMO antennas to pick up more signals and turbocharge your speeds.
Currently, 4x4 MIMO (four antennas!) is the standard for the latest 5G flagship devices.
Additionally, devices that support mmWave 5G have separate antennas just for the mmWave frequencies.
For more on understanding MIMO:
External Antenna Ports
External antennas paired with hotspots and modems can sometimes work wonders to stabilize your signal and bring in faster speeds or a usable connection in fringe areas.
Antenna ports are typically found on mobile routers and more advanced hotspots. Modern phones and tablets do not have antenna ports.
Here are the common port options and configurations:
- No Ports - No user-accessible antenna port is available - the antennas are small and internal. This is common on basic devices, smartphones, and tablets. The only way to get a better signal without external antenna ports for these devices is via a cellular booster.
- Single / Test Port - Some older mobile hotspots had one antenna port. This is not seen anymore in modern devices except in rare cases.
- Two Ports - Many modern flagship mobile hotspots have two or four internal antennas but also come with two user-accessible external antenna ports so that external antennas can also be used in a 2x2 MIMO configuration. Higher-end cellular routers tend not to have internal antennas and instead rely completely on external antennas.
- Four Ports - The main devices with four external antenna ports are routers with Cat-18+ LTE or 5G modems. Dual-modem devices can also have four ports that utilize two ports for each modem, or four ports per modem, for a total of eight ports.
NOTE: Most advanced Cat-16+ and 5G mobile hotspots with antenna ports utilize 4x4 MIMO for their internal antennas but only have two external ports. If you connect an external antenna to these devices, the internal antennas shut off, and the device is limited to 2x2 MIMO mode - cutting your potential peak theoretical speeds in half. You will have to do some trial and error in each location to determine whether the internal 4x4 MIMO or the external 2x2 MIMO performs better. The winner will vary depending on your local conditions and whether or not the local tower has been upgraded to take advantage of 4x4 MIMO.
To better understand cellular signal optimization:
TIP: Most devices with MIMO antenna ports have a "primary" port, which is the one used for upload transmission. If you're using just a single antenna with the device, you can determine the primary by trying the antenna on both ports. The one that gets better upload performance with the antenna is the primary port. In our gear center listings, we have listed the primary port for the mobile hotspots we track to make this easier. And most routers label the main port as "primary" on the device.
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In the remaining member-only sections of this guide, we go even deeper:
Deeper Dive On Cellular Modem Peak Theoretical Performance
We go even deeper into analyzing the performance capabilities of each cellular device generation- including looking forward to 5G-Advanced and even 6G cellular.
Comparing LTE & 5G Performance Capabilities
More on how different generations compare - including some real-world testing results.
Understanding Peak Theoretical Speeds For LTE and 5G
There is a simple formula that is used to calculate peak theoretical speeds. Understanding this formula can help in understanding what impacts cellular performance.
Deeper Dive: LTE and 5G Cellular Frequency Bands
More about cellular frequency bands - and the different flavors of 5G spectrum.
Summary: Evaluate Features Every 2 Years
Understanding the features of a cellular device is one of the most important criteria for determining how well it will perform for your needs.
Sometimes an upgrade to a more advanced modem can make all the difference in the world.
As technology advances and changes frequently, we recommend evaluating the capabilities of your cellular modems at least every couple of years to make sure you have the best equipment for your needs.
There is usually no need to rush to be on the bleeding edge of technology, but it definitely pays to avoid falling too far behind!
Selecting Cellular Devices
LTE Modems come in various sorts of cellular devices - smartphones, embedded routers, and mobile hotspot devices. Each has its pros and cons.
For more on the basics of mobile hotspots, routers, and smartphones:
We have specific guides to selecting these sorts of devices:
Mobile hotspot devices are small, self-contained units that receive a cellular data signal and transform it into an internet connection. They are a cellular modem and router combined. Most can create their own personal Wi-Fi network.
They are typically designed with a specific cellular carrier in mind and require a suitable cellular data plan of their own to operate. You might see them called Jetpacks (Verizon's term for them) or MiFi (Inseego's name for them).
Here's a quick video going over the features of a hotspot, and what makes one better than another:
The guides below have been hand-picked to help further your education about selecting mobile hotspots and best utilizing them in your mobile internet setup.
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