The centre of attention

Critical Comms visited the P25 Solution Centre in Sydney to get a first-hand look at the open standards ecosystem in action.

Drive along the Pacific Highway northwards from the Sydney Harbour Bridge and you soon come to Gore Hill, where the main things that stick out are two huge broadcast antennas on the site of the old ABC television studios. Drive a little further north and you come to 799 Pacific Highway, Chatswood, where two large, glass-covered office towers dominate the skyline. Inside one of those towers is an industry communications facility believed to be unique in the world - the P25 Solution Centre.

The centre is hosted within the offices of Airwave Solutions Australia. But although Airwave is the host, it has actually been put together by a whole consortium of leading communications companies: Airwave, Harris, Tait, Auria Wireless, Simoco, RFI, Icom, Zetron, Interactive Group and Codan.

Established in 2011, the centre provides a place for potential users and operators to come and see P25 capabilities and functionality put to the test. In particular, it is used to demonstrate the interoperability of different vendors’ P25 equipment, which itself is a demonstration of the open standards solidity of the P25 ecosystem.

The centre comprises: a demonstration room complete with handsets from a variety of manufacturers plus a Zetron console; an equipment room where the core switches are located; and three base stations (again, different manufacturers) located at the Gore Hill tower site.

The demonstration

The demonstration is centred around a Zetron console and a host of portable and mobile radio units from a variety of manufacturers. Present are Peter Stellino, transmission engineer and P25 Solution Centre manager, and Malcolm Keys, CEO of Airwave Solutions Australia.

Stellino conducts the demonstration, showing how the CSSI (Console Sub-System Interface) and ISSI (Inter-RF Subsystem Interface) concepts work with various combinations of base stations, core switches, subscriber units and a console, all from different vendors, communicating with one another in group calls and single calls.

Peter Stellino, P25 Solution Centre manager, with the centre's core switch units.

He begins with a description of the concept of P25 open standards. “P25 standards are all about how you connect outwards from your network - they don’t define how you do certain things internal to your network; that’s proprietary,” said Stellino. “P25 standards define how you would use your subscriber unit to talk to a PABX, for example, or what type of interface you’d need to talk to a third-party MMS system via an SNP protocol. Or what type of interface you’d need to talk to a different P25 network or third-party despatch console, or what type of interface you need from your base station to talk over the air to different manufacturers’ subscriber units.

“The whole idea of the interface is that it doesn’t require vast amounts of cooperation between vendors - it’s the opposite,” he adds. “They barely have to talk to each other, and we’ve found it has been that simple.”

First, he demonstrates one of the most basic functions of a P25 system - changing talk groups and showing how easy it is for one vendor’s handset to talk to another vendor’s handset, by just dialling up the talk group on the selector knob on both handsets. The resources needed to do it are looked after by the base station controller and the core switch. “I’ve just demonstrated some interoperability - we saw an Icom terminal working under a Tait system,” says Stellino. “Some users have seen this before, but it’s quite rare. It’s a nice demonstration to start off with, to show different vendors’ equipment on the one network. If I do something with one vendor’s handset - change talk groups for instance - I can also do it with another vendor’s handset.

“Our demonstration system has three ‘transmission sites’ all placed in the one physical site - so we have a Tait base station site, an Icom base station and a Codan,” he continued. “These are located at the Gore Hill facility owned by BAI. So this is an over-the-air demonstration, with the core switches talking to the base station controllers at Gore Hill over a VPN.”

One of the transmission towers at Gore Hill in Sydney.

The next demonstration introduces equipment from more vendors.

“So this next call is on the Auria system,” says Stellino, adjusting the subscriber units. “I’ve got a Simoco subscriber unit, but I’m talking through an Icom base into an Auria base station controller, through the Auria switch, back to the Codan base station controller, to the Codan base, and back to another Simoco. So now I’ve got four vendors. Not only that, it’s an inter-site call.”

Stellino says this usually pricks up some interest from visitors to the centre, as they’ve just seen four different vendors for the first time ever, on an inter-site call, on a P25 trunk call, effectively in one network.

“Next, a very important call demonstration,” says Stellino. “Most traffic volume today, still, in government and critical agency networks, is from console to subscriber unit, followed by subscriber unit back to console; third would be subscriber unit to other subscriber units. As you can imagine, the CSSI interface, that standard P25 interface which allows a vendor to interface with a third-party console, is very important.”

With a few clicks of the mouse on the Zetron screen, Stellino connects networks together with a patch on the console and successfully makes a call.

“At this point, most P25 users are quite excited because they can’t see that sort of demonstration anywhere else worldwide, with this number of vendors, with a patch on a third-party console, going through different base station vendors and switch vendors,” says Stellino. “We don’t believe that’s reproduced anywhere else in the world at this stage.”

A unique feature

Everyone in the industry is aware of instances of emergency services being unable to talk to each other when required, because each of those services are on their own networks. The next demonstration showed the solution to that.

“Technically, we could do it by patching two systems or talk groups together via the console, but usually the agencies have their own console dispatch systems,” says Stellino. “So how do you patch together a patch group when you can’t see the other people’s talk groups on your console? The ISSI is the interface to overcome that, and it shows that I can front up to an incident and roam to the common incident talk group.”

ISSI enables two completely different P25 trunked networks to interoperate in a seamless way. Stellino switched several handset units from different vendors to the common talk group and from one of them successfully made a call that was received on all the others.

The P25 Solution Centre brings together hardware from many different manufacturers to demonstrate how they can all work together under the P25 system.

“That’s the call which we believe is not demonstrated anywhere else in the world; it’s unique to this centre - an actual ISSI call between two different trunked P25 network vendors,’ says Stellino. “You’ve just removed the dependency on the console to manually patch you - you’ve used open standards based ISSI to get to a common talk group over two totally separate radio networks. That’s something we’re very proud to demonstrate, because we don’t believe you can see it anywhere else.”

“So two good examples of this might be NSW Police and NSW Ambulance,” adds Malcolm Keys. “Another example would be Victorian SES and NSW SES, who provide mutual aid to each other. They’ve got their own networks, but by simply preprograming and enabling this feature they can go straight over the border and operate, even though they’re on someone else’s network.”

“One thing even more powerful than that, which brings more freedom, is that I can do an ISSI call and I don’t have to go to a common talk group - I can just make a point-to-point or unit-to-unit call,” says Stellino. “If I’m the incident on-ground commander wanting to talk to my counterpart in another agency, I can just call him or her individually using the unit’s unique P25 IDs - a unit-to-unit call through the ISSI system.”

Stellino demonstrated the concept using one handset to call another, by dialling in the second handset’s identifier. “The ISSI unit-to-unit demonstration I just did not only punched through and made an ISSI tunnel from one unit to another, it didn’t interfere with the talk groups these radios are set on. It was just unit-to-unit. This kind of demonstration is a more complex call set-up, and it’s the ultimate demonstration we can do here in the PSC.”

Interoperability

For those who’ve not experienced P25 before, a visit to the centre can be quite an eye-opener. “Sometimes we get people who have an FM analog, two-way radio background, and these older systems can be a little bit scratchy and noisy with in-built analog noise. Sometimes this is the first time they’ve heard a digital PTT,” says Stellino. “The good thing about P25 is that it really does reproduce the voice sound quite nicely.”

“It’s actually a radical change from old analog modes,” adds Keys. “Even though we’ve only got three base stations lit up at that site [Gore Hill], there could be literally hundreds of talk groups with different users who will light up only when that talk group is requested, which enables a vastly different operation model to be deployed. And I must say that it can take organisations a fair while to understand how to take advantage of that.”

Visitors to the P25 Solution Centre can see a variety of call types made using different combinations of vendors' equipment.

In the two and a half years in which it has been operating, the centre has had numerous visits from existing and prospective P25 customers, as well as vendors wishing to test the interoperability of their equipment with that of other vendors.

“We had a vendor in here testing their unit-to-unit call to a different vendor’s units, through the ISSI connection, and the call didn’t work,” says Stellino. “We were able to get right into the logs and see what was going wrong - which in that case was due to some differing implementations of P25 protocols. That’s one example of vendors coming in and making use of the centre.”

“If a government agency is thinking of purchasing 10,000 radios, they want to be very confident they’re not going to have interoperability issues. And that’s partially what this centre is for,” adds Keys. “The vendors also want to show that they’re willing and keen to play in the open standards space, otherwise their offerings suddenly become less attractive. Although they are competitive suppliers, they’re willing to band together to show that the ecosystem of P25 is a successful ecosystem and then compete with each other in a vibrant and competitive market.”

In addition to lots of attention from Australian firms and agencies, the centre has also had visitors from New Zealand and China, and interest is now being shown from the USA.

“What we demonstrate is technical interoperability,” said Keys. “When people talk about interoperability, they often merge the concepts of technical and operational capabilities. And so we can see from the demonstrations here that technically there’s as much interoperability in the P25 ecosystem as you could possibly need. The real constraints are on the operational procedures and processes and training. Over time the more mutual-aid incidents agencies have to deal with, the more they learn to rely on the interoperability that’s built in to their network.

“In Australia, we’re sort of halfway - we don’t quite have full technical interoperability between all government networks, so at any one given instant you might find that police and fire first responders, for instance, are unable to speak to each other,“ said Keys. “But the industry is on track to achieve the government’s (COAG) 2020 vision of having everyone on interoperable trunked P25 networks. By this time there should be no more impediments to technical interoperability.”