Boulder Lab Checks AT&T’s Work on FirstNet Rollout, Services
Monday, April 23, 2018 | Comments

First Responder Network Authority (FirstNet) technical staff in Boulder, Colorado, are testing and collaborating with partner AT&T, while also integrating equipment and conducting its own tests in the Innovation and Test Laboratory.

FirstNet’s Boulder staff of around 50 are composed of different teams looking at the end-to-end service and Long Term Evolution (LTE) core, devices and radio access network (RAN), and applications for the devices.

In March, AT&T launched the FirstNet dedicated public-safety core, but FirstNet engineers have been testing and verifying public-safety services since last August. FirstNet staff traveled to AT&T’s lab to test priority service last August, and AT&T official came to Boulder a month later to demo priority service. Last December, FirstNet engineers went to AT&T’s Redmond, Washington, lab for pre-emption tests.

“We validated, observed and tested that on the commercial network, on a fully loaded cell site in the lab,” said Michael Van Zuiden, director of FirstNet labs. “We focused on those commercial services for the early FirstNet subscribers.”

2018 brought testing for the LTE public-safety core. FirstNet staff tested a list of features at three different “checkpoints” or dates in AT&T’s lab. Tests conducted Feb. 6 – 7 included voice over LTE (VoLTE), emergency calling, video streaming, device authentication and others. From Feb. 21 – 23, checkpoint two, FirstNet tested location, enhanced push to talk (PTT), handover, quality of service, priority and pre-emption (QPP), among others. The March 20 – 23 tests verified mobile virtual private network (VPN), internet of things (IoT), QPP incident command portal and uplift, and rainy day/failover.

“The engineers tested QPP under a loaded cell site on the FirstNet core,” Van Zuiden said.

In addition, they tested Third Generation Partnership Project (3GPP) multioperator core network (MOCN) — a term for RAN sharing — between the AT&T commercial and public-safety core networks and sharing the RAN for band 14 and all AT&T’s commercial bands.

“MOCN is the way to do RAN sharing,” said Jeff Bratcher, FirstNet chief technology officer (CTO). “In Europe they do a lot of this to share these cell sites with other operators and reduce the cost. Two different operators’ cores are connected to the same RAN.

“Traffic from the RAN is split to the different cores, which is predicated on our network identifier, one for FirstNet and one for other commercial bands. That’s how the system knows they are a public-safety subscriber because they are on the FirstNet network ID. It’s separating public-safety traffic from commercial.”

Indeed, in an April 10 demo at the lab, a call on a FirstNet band 14 device was made while a commercial call was underway. A test system showed data throughput slowing for the commercial user, while the FirstNet device’s data throughput increased or remained steady.

Also during the final set of tests, failover core network and redundancy tests were conducted. If FirstNet loses connectivity, public-safety users would fall over to the commercial core.

“That was our due diligence ... Things went fairly smoothly but if we found issues, AT&T followed up in the next checkpoint to address what we needed,” Van Zuiden said.

Now that the testing of FirstNet’s dedicated core is complete, AT&T is beginning to move FirstNet users who didn’t participate in the controlled introduction over to the FirstNet core, an AT&T spokeswoman said.

The FirstNet lab is equipped with AT&T band 12 and 17 eNodeBs, along with band 14 equipment. “We’re now connected to the FirstNet core, and through MOCN, we’re also connected to the commercial network,” Van Zuiden said. “Three weeks ago, we made a VoLTE call and a data session through the FirstNet core network.”

On April 10, staff also demoed a FirstNet band 14 voice call on a device with a FirstNet subscriber identity module (SIM) through the FirstNet core. The AT&T spokeswoman said FirstNet SIM cards are available in AT&T retail stores for eligible first responders who sign up for service via the FirstNet subscriber paid offering.

AT&T said if a first responder wants service dedicated to public safety but is not required to switch SIM cards, that suggests the first responder will still be operating on a commercial core. A move to a physically separate, dedicated public-safety core requires a SIM card switch.

Bratcher said AT&T is adding its LTE equipment to LMR sites when it can but it needs fast backhaul to use the LMR sites. AT&T will also offer metro cells to enhance coverage in specific areas.

Commercial LTE implements 2-by-2 multiple input multiple output (MIMO) technology. The FirstNet core has 4-by-4 MIMO transmit and receive, which doubles the efficiency and offers extra redundancy and throughput. 5G networks will use massive MIMO, Bratcher said.

FirstNet is in the process of connecting its Boulder lab to AT&T’s Redmond lab, which will allow FirstNet engineers to test new features before deployment.

FirstNet’s device team began verifying its processes early this year and received the first FirstNet SIMs in February. Earlier this month, the National Institute of Standards and Technology (NIST) released a list of devices approved for the FirstNet network, which the Boulder staff played a large part in, said Joe Martinet, FirstNet director of devices. He said more devices are expected to be announced later this year.

Several applications are available in the FirstNet store; however, a list of certified apps is only available to FirstNet subscribers. FirstNet is verifying QPP and other public-safety features such as battery life and performance. In March, ESChat’s secure PTT application achieved the “FirstNet certified” validation for apps.

The lab first opened in November 2016.

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