BY MIKA SKARP
When we talk reliability in Public Safety networks, what are actually talking about? Fresh on heels of the National Sheriff’s Convention in New Orleans, where the US’s contentious immigration policy hit fever pitch, many great behind-the-scenes discussions around public safety communications came to a full gallop.
What are the key ingredients for a 100% reliable, failsafe critical communications network? Can one carrier alone carry the water, and how can we ensure that the kinds of heartbreaking failures that compounded the tragedy of 9/11 never repeat themselves?.
I am sure these will come to a head at next month’s Association of Public Safety Communications (APCO18) conference. But with these themes fresh in mind and public safety concerns in high season, I thought I’d share some perspectives on what for me are the key ingredients for the public safety networks of the future. But first, a primer.
5 Keys to Building a Reliable Public Safety Communications Network
Public Safety Networks Go Commercial
While just 10 years ago it would have been unthinkable, it is now coming to be the norm to use commercial networks to serve public safety needs as well. FirstNet has done an enormous job building the spec for this in the context of the US’s emerging Public Safety communications ecosystem, and it now it is really starting to take root.
With the yeoman work of the Public Safety Communications Research (PSCR) with whom we’ve been honoured to collaborate for many years, we now are seeing the arrival of a wave of public safety specific applications and tools coming to global markets. This is not only saving taxpayers a lot of money, as costly, outdated propriety networks are being shut down, but it’s also saving lives.
Still, and with all of the progress, there remain some very valid concerns about the true reliability of commercial networks. Perhaps needless to say, reliability means something very different on a conference call driving to work as it would if, perish the though, the bridge gave out below you and the coordination of hundreds of First Responders was a matter of life and death.
So what does reliability really mean when we’re talking public safety? If you’re a green, freshly minted public safety engineer this may bring tears, but it’s akin to an onion, with many more layers than you might think.
But in the interests of keeping it sliceable, here, for me, are the key ingredients, or in the language telecom and onions, the main layers:
Layer 1: Coverage
“Where there is no coverage there is no communication”
It may sound like a truism, but where there is no coverage there is no communication. This is without a doubt the very bedrock of failsafe critical communications, and Public Safety professionals demand the greatest and best coverage of all.
That means wide coverage (not just across a city, but spanning national and state parks and water bodies), as well as narrow coverage (think inside buildings and subways and parking lots). Beyond primary network spectrum, both of these can be addressed with low frequency meshes. But what happens when even those overlays fail? Can a single carrier network ensure public safety grade reliability?
In truth, it’s not just a matter of having coverage, but of being able to access the strongest signals, and that means being able to select from several networks to meet the demands of any incident.
Going Multi Carrier
In most counties you will find at least three different operators on the job. It perhaps goes without saying that by combining the strengths of all available networks you’ll achieve dramatically better coverage, indoors and out on the range, than you would relying on a single player, no matter who they are.
This has been perhaps one of the bigger barriers to moving public safety agencies and the government bodies that support them away from dedicated networks. But with the rapid acceleration of technology, particularly in the area of multi-path routers and companies like Goodmill Systems, and with the coming wave of eSIM devices, this not only solves the “all eggs in one basket” problem, but introduces layers of redundancy critical to critical communications.
And with 5G’s introduction of relatively high 3.5 GHz frequency, which exhibits good coverage behavior, we’ll soon have the blankets of strong connectivity to ensure that no first responders are ever left out in the cold.
Layer 2: Capacity
“Application-Aware Network Slicing & Local Control are the sirens and lights on the wireless roadway”
Regardless of how many emergency dramas they may watch on TV, most “civilians” still think of walkie-talkies and ambulance CBs when they hear “communications for public safety”.
But in the real world of live situation analysis, facial recognition and multi-source body cam intake and playback, applications are the name of the game. And as the primary tools of the public safety trade, Application-Aware Network Slicing & Local Control are the sirens and lights on the wireless roadway.
And just as consumer traffic only increases, a wave of new, high capacity demand public safety applications are just as hungry, if not more, and much, much more important.
Just as there are already provisions made for applications like push to talk with dedicated bearer QCI values to serve their needs, the sheer volume of new critical communications applications makes Application-Aware Networks absolutely essential. Many different applications, means many different capacity requirements to work as designed.
In video applications, for example, adaptive modulation can be used to ease network load, but we need to be able to deliver crystal clear HD video and at the same time ensure less than 20ms delayed control signals to drones and other robotic machines using the very same network.
Here Network Slicing provides the solution, dramatically expanding on the use of unique QCIs for different applications, while managing and orchestrating the capacity they deliver with pinpoint accuracy, to ensure that the network will never be congested. This kind of next-generation, intelligent capacity management lies at the heart of solutions like Cloudstreet’s Dynamic Profile Controller (https://cloudstreet.co/dpc/).
In addition to providing key internal business logic, it also provides an arsenal of tool, including an interface for profile, user, device and application management on the fly. This is the essence of Local Control and LTE QoS Priority and Preemption that we helped the PSCR to specify. (https://www.netmanias.com/ko/post/cshare/5232)
Layer 3: infrastructure (Backhaul, Cooling and Physical Infrastructure)
“Stay Calm and Keep Your eNodeBs Cool”
To ensure that the network is reliable from end to end, we need to look at the hardware and a good place to start is with eNodeBs and their sites. As with coverage, without eNodeBs there is no communication and that means guaranteeing adequate protection and cooling capacity even in the most extreme conditions including increasingly frequent heatwaves and sandstorms.
They also need to have redundant transmission lines to the core network. Meanwhile, those high flying antennas, standing need to remain still even in high category hurricanes. While this is basic network design in practice, when elevating the reliability requirement, we need to make decisions on how to preempt and address extreme conditions to keep things running.
But because it’s virtually impossible to anticipate every imaginable situation, and no infrastructure is invincible (think meteor showers), it’s as much about making provisions for being able to quickly deliver plug and play, temporary infrastructure at a moment’s notice.
Layer 4: Power
In every catastrophe, power outages happen. But when designing public safety grade network, we need to plan the power supply for eNodeB and transmission lines to ensure they keep running. In the Core Network it is much easier to provide back-up power because it is centralized.
Of course, there are backup batteries, but they come with a cost. It is also possible to do power management of eNodeBs in emergency situations, but this cuts into capacity and in those situations, time is the only factor.
How can you cut down the time to return electricity to needed eNodeB sites. The standard for existing dedicated public safety networks should be the rule of thumb.
Layer 5: UE
Though this is the place we often start, the last level is the User Equipment. This is last on the list not only because devices are easily swamped out but because they will tend to out last nearly any catastrophe that humans can persevere.
And while UE is actually harder design than most of our other equipment in the network it is far more rugged. And even when the network is down, in some special cases we can actually have direct UE to UE communication.
Perhaps even more importantly from a public safety perspective is the fact that UE continues to signal GPS with or without their wireless networks and what’s more they generally contain a good amount of pre-downloaded information about a location and other things.
This on-device information will likely have the location of hospitals, police departments and in some cases floor plans of buildings etc. Of course, you can’t have global information in your device, but you can update this emergency information set frequently.
Designing reliable communication networks is both a critical and delicate job, and it takes a truly holistic approach. Perhaps needless to say there is no silver bullet and there will always be situations in which communication won’t work does not matter what technology is used, but even that scenario can be prepared.