In-Building
Building confidence
Sam Fenwick looks at some of the current thinking and issues around the provision
of in-building public safety broadband coverage in both the US and the UK
While at IWCE in Las Vegas, I attended
a session that discussed how FirstNet
interacts with the regulations that govern
(as well as the practicalities around)
in-building coverage for public safety.
Andrew Ruschak, wireless technology consultant at Stantec,
voiced some of his professional frustrations around “the lack
of information”, including the need for clarification on if or
how Band 14 signal reinforcement should be done, who bears
legal responsibility for it and who pays for it. He noted that
the design and technology assumptions around LMR/public
safety distributed antenna systems (DAS) can’t be applied
to carrier-based DAS and added that the guidance that
consultants need from carriers and FirstNet/AT&T to advise
their clients is “yet to be forthcoming”.
Ruschak also said that existing code-compliant DASs have
very little to no capability for adding FirstNet, for a variety
of reasons, including the fact that carriers do not generally
allow the use of bi-directional amplifiers, which typically feed
public safety DAS systems in the US (MNOs are concerned
about the impact on the rest of their network and BDAs
“are notoriously bad for raising the uplink noise floor”). He
expects that mobile network operators will need to have a
very close working relationship with the authorities having
jurisdiction (AHJs). The key question in his view is, should
carrier-LTE coverage be as important as LMR coverage
in buildings in fire and NFPA (National Fire Protection
Association) codes – ie, consider FirstNet as an Emergency
Radio Responder Communications Systems (ERRCS)? “If the
answer to that is ‘yes’, everything changes.” Ruschak believes
expectations for in-building LTE coverage for first-responders
will increase in line with their use of data-based applications.
He also noted that while Band 14 (in 700MHz) is the
spectrum that FirstNet has provided to AT&T, the latter uses
carrier aggregation, and for first-responders to see the best
performance in terms of data throughput, the systems will
need to support multiple bands.
John Foley, general manager, Safer Buildings Coalition,
highlighted the way that the NFPA code is performance-based
rather than prescriptive and therefore whether or not LTE is
required hinges on if the AHJ opts to put the frequency pairs
used by this service on the list that it is obligated to maintain
for system designers. He added that this has already happened
in Washington D.C. – FirstNet is required to be present
within the district in non-federal buildings. He said the
existing code also says that the signal shall be provided by the
building owner, while also noting that it is in AT&T’s interest
to provide guidance so that these systems don’t mess up its
radio access network. Foley also said that the Safer Building
Coalition is “working at the highest levels to negotiate what
that might look like”.
Both Foley and Neil Horden, chief consultant at Federal
Engineering, emphasised the need to consider how the
relevant codes are enforced and interpreted by AHJs, and
Foley added that those working on projects therefore need to
have good communications with the local AHJ.
14 www.criticalcomms.com April 2019
Adobe Stock/VanHope
/www.criticalcomms.com