Private Land Mobile Radio (LMR) has been the go-to option for public safety agencies that demand guaranteed communications in order to respond effectively to emergency incidents, and many millions of frontline personnel rely on these networks and devices around the globe.
Now, the provision of high-bandwidth data communications over 4G/LTE mobile broadband networks is driving a new class of data-driven services and new thought regarding what is now possible within public safety.
When it comes to delivering mission-critical services, the truth is that you can always be ‘more’ mission-critical, and you can certainly be less. The ability to replace LMR with broadband is going to depend on a number of factors, not least establishing what is ‘good enough’ for each customer’s mission-critical needs.
Uptake is also expected to increase as LTE protocol standards are ratified, and as spectrum and budget enable network deployment that is ‘public safety ready’, and able to meet expectations of both coverage and capacity.
But rather than being revolutionary, the changes the industry must now go through are really more evolutionary, and will depend as much on the experience gained from LMR as the data-centric potential of LTE.
What does the user want?
Understanding the particular needs of the end user is key when introducing any new technology. The mission-critical-communications industry is no different from other industries, with a range of standards and technologies all vying to deliver the best products and services to the customer. So identifying the frontline needs for mobile broadband-based public safety services and applications has to be the starting point.
The focus on technologies, while valid, somewhat misses the point of where public safety is heading. Consideration should really be given to the ability to provide future-proof mission-critical information and communications services to public safety users regardless of the technologies deployed.
This is why the adoption of LTE is going to be an evolutionary one, where technology agnostic delivery supports fully integrated voice, data, devices, platforms and user services, all with familiar, easy-to-use interfaces that deliver operational excellence for the connected police or fire officer, and paramedic.
The common denominator here is the need to continually improve communications, in this case for the emergency services and affiliated public sector agencies.
In the LMR world these can be varied, from coastguard and border patrol, to highways, event organisers or GPs in local health centres. So when it comes to LTE-based services for public safety agencies, this means bringing greater choice to the user and improvements to service.
With LTE this is going to include the immediate provision of content (voice, video, data, graphics, audio and messaging) to multiple users, and integrated services that make use of some or all of this content. Of course, every deployment is potentially going to be different and will undoubtedly mix to varying degrees LMR, commercial LTE and private LTE networks.
A majority of users, certainly early on, will be best served by a combination of LMR and LTE. A case in point is Harris County in Texas, US, which has extended the existing ASTRO P25 LMR network, adding digital IP-based voice and data services over LTE broadband for 400 dispersed public safety agencies across 1,800 square miles of the state.
The Harris County network is supporting real-time video intelligence, streaming video between command, vehicles and handhelds and, crucially, push-to-talk (PTT) voice services between the broadband network and the ASTRO P25 network.
This brings us to the ongoing delivery of mission-critical communications, where voice services must be the constant within any mission-critical network. They need to be efficient, resilient, secure and affordable, regardless of the technology or standard being deployed.
Push-to-Talk over LTE
Most smartphone users will be familiar with the 4G/LTE, with its super-fast mobile broadband services delivered over commercial networks. Videos, photos, messages and calls are diced up into small packets of data, which are transmitted over the network by high-speed radio signals and then reconstructed into recognisable images or voice calls.
However, the potential for calls to be interrupted has meant that commercial mobile networks have not been deemed reliable enough to carry voice communications for public safety agencies. Within private LMR, the expectation is for an instant, real-time connection 99.999% of the time. This is the PTT capability that is very familiar and depended upon by emergency services officers.
The knowledge and trust an officer has that when they hit the PTT button on a radio they will get instant conversation with their entire team is the most basic and important of all mission-critical applications.
For mobile broadband to be a realistic bearer for public safety, mission-critical voice services must be able to integrate with the many new connected public safety services on offer, but never to the detriment of that critical voice connection.
While a private LTE network for public safety will be the ultimate goal, the issue of frequency allocation that many nation states continue to debate, and the current high costs of rolling out private LTE city-wide – let alone nationally – means many agencies will look to commercial carriers to support initial mission-critical LTE services.
While data for public safety applications will be carried solely over the commercial mobile operator’s network, mission-critical voice and PTT functionality needs to be treated differently. The management of PTT calls is not carried out on the mobile operator’s network; instead a PTT Gateway needs to be established on the public safety supplier’s own servers.
This has a threefold advantage; first the gateway is technology agnostic, meaning the gateway enables real-time communication between a variety of devices, either a commercial handset with a soft button or ruggedised handsets with a dedicated hard PTT button, operating on any bearer, including TETRA, P25 or LTE.
Second, this approach is highly scalable, supporting concurrent calls, which is why the third advantage, the ability to manage call prioritisation becomes so important.
Over time, LTE will start to provide the ability to manage at a more granular level the varied functionality of public safety systems, using features only when needed and enabling users in the control room to change how they react and control the resources dispatched to an incident.
The provision of agnostic applications, which will work with any computer aided dispatch (CAD), will enable a commander to dynamically assign group calls from anywhere, defining a region on a map, circling all call signs and then making a call to all in that area. Those selected, whether an individual or talk group, receive a familiar PTT experience no matter the device or network.
The world of public safety is changing, and the evolution is coming through technical interoperability and the ability to transfer services across varied bearer technologies, including TETRA and LTE.
The ability to adopt LTE or to collaboratively extract the best elements from multiple bearer technologies should be a core requirement of any commercial or public safety organisation engaging in the evolution of mission-critical communications service delivery.
As the bearer itself becomes less relevant, what truly characterises an advanced service is the ability to deliver maintained performance for critical voice and then data services. This quality of service and the ability to prioritise user traffic over multiple bearer technologies for the same talk group is what will define the next generation of public safety.
The advantage of the evolving process described is that it enables users to be more specific in terms of where they want to reside on the mission–critical scale, being much more granular about what is ‘good enough’ to meet mission-critical or more demanding public safety operations.
With a technology agnostic approach, users will eventually be able to move from a combined LMR/LTE model and choose what is ‘good enough’ for all their mission-critical needs, reducing costs and complexity while delivering enhanced services that improve contextual awareness and raise frontline intelligence to make cities safer and enable communities to thrive.