Freedom Robotics Guide to Cell Routers for Robot Connectivity

At Freedom Robotics we have worked with 100s of robotics customers that use LTE connectivity to deploy robotic applications. Depending on use case, budget, and reliability requirements, the solutions they’ve deployed fall into three general categories:

• Low-cost - USB LTE stick
• Mid-cost - Entry-level commercial LTE routers
• High-cost - Reliable high-end routers for commercial options

Here we compile specific routers from each category that we’ve deployed for our customers with great success.

Low-cost USB LTE sticks

While not a hardened router solution, USB sticks (like the Huawei E8372h-517 pictured here) are common in robotics. We’ve seen robot fleets with this class of router provide decent connection quality. They are also cheap enough to add as a fallback or in addition to the other solutions listed here.

USB LTE sticks are not hardened industrial solutions, but they quickly and affordably can provide LTE connectivity to your robot. The Huawei E8372h-517 is a standout in this category. Here are some of the highlights:

Specs:

• 150 Mbps downlink and 50 Mbps uplink - very fast for a USB LTE Modem
• You can mount an external antenna as It has two TS-9 connectors for an external antenna
• It accepts one cell card
• It can generate a wifi hotspot
• Low cost: $65.80
• Low power consumption
• Operating temperature –10℃ to +40℃

Who is this solution good for?

A USB LTE stick is a fantastic option for quickly and affordably testing prototypes outside wifi range. However, taking your robot into production with a solution like this is not recommended. Since USB sticks are a consumer-grade product, you should expect periodic connection dropouts and frequent replacements. They are also not advised for mission-critical use. 

Mid-cost entry-level commercial LTE routers

The Microhard Dragon-LTE-100-GL will provide a reliable connection over a single sim and allows the flexibility to design this product into your robot without breaking your budget.

The entry-level commercial router highlighted here is the Microhard  Dragon-LTE-100-GL. This router won’t increase your connection speed over an LTE USB stick, but it will increase connection reliability which is much more important for most applications. It is still only a single sim router designed to be embedded into a system and deployed in production. Here are the specs:

• 150 Mbps downlink and 50 Mbps uplink
• The retail price is $249
• Connects through ethernet
• Accepts either LTE signal or wifi
• Can generate a wifi hotspot
• Operating temperature –40℃ to +85℃
• Max power consumption is 4 watts
• VPN Tunneling and firewall rules through ACL
• Can generate data usage alerts
• See full specs here

Who is this solution good for?

This router is a good fit for robots in an operational environment that is geographically limited and has reliable cell coverage from a single carrier. It is also best suited for robots not remotely logging mission-critical data and able to receive mission commands remotely and from humans in the same working environment.

High-cost, high-end commercial LTE routers

 The PEPLINK MAX Transit DUO CAT 6 (MAX-TST-DUO-LTEA-W-T-PRM) maintains a fast and stable connection.

When maintaining a fast and stable connection is paramount to the success of your application, you will want a high-end commercial LTE router. This class of router enables faster connection speeds, dual sim capabilities, high shock and temperature ratings, and the ability to manage your connections via cloud management software. 

The router highlighted here is the PEPLINK MAX Transit DUO CAT 6 (MAX-TST-DUO-LTEA-W-T-PRM). Here are the specs:

• 300 MBps down and 50 up
• Dual sim with instantaneous switching (many comparable routers can take 3-5 minutes to switch or require additional hardware)
• Can monitor 2 cell bands from the same carrier 
• Supports SpeedFusion and allows the modem to simultaneously use data from each cell card (this feature does not come configured out of the box and requires additional licensing fees)
• The retail price is $799
• 18 watts max power consumption
• 1.3 lbs.
• Cloud management software
• 2.4 and 5 Ghz wifi connectivity
• Two dedicated wifi and cell antennas
• Shock and vibration certifications
• Operating temperature –40℃ to +65℃
• GPS is available (but difficult to port into ROS)
• See bandwidth compatibility chart below
• See full specs here

There is also a Cat 12 version of this router (MAX-TST-DUO-LTEA-R-T-PRM) which is dual cell, rated at 600 Mbps down and 75 up, and can monitor 4 cell bands from each carrier simultaneously. It retails for $999. See full specs here.

If connection speed is of utmost importance, PepLink also makes a Cat 18 version of this router (MAX-TST-GLTE-G-T-PRM) which can achieve an incredible 1.2 Gbps down and 150 Mbps up and retails for $749. It is, however, a single sim router. See full specs here.

Who is this solution good for?

This class of router is best suited for robotic applications that transmit mission-critical data and are teleoperated, and where downtime is expensive and physical access to the robot is limited. A major advantage of investing in this type of router is the time and energy it allows you to spend on your core product rather than connectivity issues. 

Comparison chart:

Other recommended router brands:

There are many additional types of routers one can consider for their project or product. Here are three more products our customers have experienced success with:

• Cradlepoint: The IBR600 series routers are similar to the PepWave Max Transit Duo CAT 6, but feature increased switchover time for dual sim routers. The retail price is  $509.
• Mushroomnetworks: They make REALLY high-end routers with up to 8 sim cards. Consider these when cost, size, and power are not limiting factors, and connectivity is paramount.
• Multitech.com: They have a great line of products that run the spectrum of entry-level to industrial LTE connectivity solutions.

If you are an advanced user seeking a custom solution, Mitrotik sells router boards with attachable mini-pcie slots and modems. It delivers flexibility and lower costs but requires a significant upfront investment of time and energy.

Band compatibility: an important consideration

An important aspect of selecting a router is its compatibility with your carrier. You must ensure your router selection offers stable coverage on the carrier data plan of your choice. Further, routers and carriers only operate on specific bands. Compatibility is critical!

Conclusion

Before buying a router, you’ll need to know the following:

• Your environment. Understand which carriers have superior coverage in your operation environment of choice.
• Your data requirements. Understand how much data and what connection speeds you require. 
• Your carrier. Understand your carrier’s data offerings and select a plan that fits your business model.
• Your speed and reliability requirements. Understand the speed and reliability requirements of your application before selecting your connectivity solution.

If you have tried deploying a robot outside of a lab you already know many things can go wrong --  robots are experts at finding edge cases! Maintaining a stable connection to your robot and using great software to monitor and control your robots will simplify things tremendously, speed up your time to market, and enable you to scale when ready.