Sierra Wireless AirCard 313U: an early 4G stick

Sierra Wireless made its name with AirCard PC Cards for laptops, and the DC-Files index of 2010 listed several of them, from the AirCard 850 and 881U to the 885 and 888 "Compass" models. The AirCard 313U belongs to the next generation: an early LTE (4G) USB modem from around 2011, sold through operators such as AT&T.

These notes cover the 313U and what changed when USB modems moved from 3G to 4G.

The hardware

The 313U is a compact stick with a swivelling USB connector, so it could sit upright or flat beside a laptop. It supports LTE as well as HSPA+ fall-back, which means it can still connect on 3G-free networks if its LTE bands match the operator's. That band question is the key one: early LTE devices supported only a few frequency bands, often just the ones used by the operator that sold them.

Watcher software

Sierra's connection software was called Watcher, a name that goes back to the early AirCards. Operator versions had their own branding. As with Huawei and ZTE sticks, the software stored profiles, managed connections and showed signal and data use.

The older AirCards in the index used the same family of software on Mac and Windows, which is why the 2010 pages often listed a single Mac disk image for several models.

What happened to AirCard

In 2013 Sierra Wireless sold its AirCard business to Netgear, which continued the name on mobile hotspots and USB modems. Sierra itself moved its focus to embedded modules for machines and vehicles.

Using one today

Because it has LTE, the 313U has a better chance of working today than any 3G stick, provided your network uses one of its LTE bands and the stick is not locked to another operator. On Linux it is usually handled by ModemManager. For quick, low-latency use, from video calls to keeping an eye on live odds while travelling, 4G was a real step forward over 3G, mostly because of shorter delays rather than higher headline speed.

Quick facts

Item	Notes
Type	LTE USB stick with HSPA+ fall-back
Connector	Swivelling USB plug
Software	Sierra Watcher or operator version
Key check	LTE band support and operator lock
Brand history	AirCard line sold to Netgear in 2013