Paving a digital future with P25

The events in the US and around the world since September 11, 2001 have spurred increased popular interest in public safety communications interoperability.

Growing concern has driven many countries to address homeland security concerns by ensuring that their public safety communications is standards-based and interoperable with other systems. This is one of the drivers for P25, a feature-rich, secure and scalable digital radio technology.

P25-compliant radios can communicate in analog mode with legacy radios in either digital or analog mode with other P25 radios. The P25 standard exists in the public domain, allowing any manufacturer to produce a P25 compatible radio product.

Specifically, P25 systems can be maintained and upgraded over the system's life cycle, thus meeting user requirements, achieving interoperability and security, promoting committed manufacturers to provide compliant products, fostering competition and achieving cost-effective emergency/safety communication solutions.

The standard was first issued more than 10 years ago and today more than 660 operational P25 networks exist in over 54 countries. The number of P25 users is expected to increase to more than two million by 2008 according to a recent IMS research report.

Apart from interoperability, P25 offers several other significant benefits to an organisation looking to adopt a digital solution.

First and foremost it ensures security of communications including encryption. It allows full backward compatibility with existing analog systems so organisations don't have to worry about migration from analog to digital.

There is also no degradation of coverage compared with analog systems. P25 also is highly scalable and offers improved audio clarity, which is essentially the same whether the user is close to the transmitter or far away.

Comparisons are often made between the P25 standard and the European TETRA protocol.

While both enjoy a large installed base and user satisfaction, there are some key differences.

The focus of P25 is coverage rather than capacity and backwards compatibility to existing analog users. This makes it a good standard for conditions in Australia and New Zealand - where we have vast areas with little population to be covered.

Both standards provide a much needed increased level of security of communications when compared with analog but P25 has a tighter definition in the standard for end-to-end encryption.

For instance, P25 ensures that secure communications are carried right from the mobile or portable radio through to the dispatch centre without opportunity for intercept along the way.

P25 is becoming increasingly adopted by public safety agencies in Australia and in recent times a number of suppliers, including Tait have begun offering equipment compliant with the standard.

This has seen a sudden drop in pricing of equipment and supports the case for a standardised multi-vendor environment from a purchaser's perspective.

The development of P25 equipment in VHF, UHF and 700/800 MHz frequency bands, makes it a digital standard with broad appeal, not just to public safety users but also to the public service, enterprise and commercial sectors.

Such is the awareness of P25 in Australia and New Zealand now that Tait is fielding enquiries from numerous organisations outside core public safety.

Tait is striving to de-mystify P25 and this is evident in its solutions which readily enable a single site or multi-voted site applications. Various P25 suppliers in Australia have tested interoperability of terminals and it is now evident that the industry is ready to support a healthy multi-vendor environment.

With regard to multi-vendor systems, there are still traps for purchasers who might assume that buying into a standard guarantees them multi-source systems. This may not necessarily be the case.

In the P25 standard there are mandatory features which suppliers must comply with; there are options specified in the standard which may or may not be implemented by all suppliers and then there is still an opportunity for manufacturer-specific options to be deployed.

There are also some system level interfaces which are now becoming available in the standard. For instance, the FSI or fixed station interface standard to interface a base station to a console or a base or cluster of voted bases to a trunked system. While there is a healthy multi-vendor environment in Australasia for conventional P25 systems, this is not necessarily the case for trunked systems and so it is incumbent on purchases of such equipment to work proactively with vendors to ensure such an environment otherwise they will remain tied to a single source situation.

Tait provides complete solutions: portable and mobile terminals, base stations and IP-based networks. The company has developed a complete P25 portfolio for conventional radio applications which are suitable for addressing the vast areas of rural Australia.

Migration of such systems from analog to digital today is a straightforward process. Organisations can install digital IP links between sites and numerous low cost solutions are available to achieve this.

Tait TB9100 digital base stations have built-in IP interface for audio and site interrogation for maintenance purposes and built-in voting with voting data carried over the same IP links.

Organisations can provide P25 portables and mobiles to the fleet and the company provides a range of full keypad and non-keypad portables and mobiles together with a range of accessories.

Users can migrate from the analog base stations to the new digital base stations which will transparently pass either analog or digital traffic - hence mixed fleets of analog and digital users can operate on the network whether they be existing analog terminals or even the new digital terminals operating in analog mode.

Users wanting to move to digital are looking for a manageable bridge. P25 with its support and interoperability with a broad range of analog radio systems offers the most cost-effective pathway.

The scaleable nature of P25 and the ability to offer conventional, trunked, simulcast and hybrid solutions are other key reasons why this standard is Tait's primary digital focus.

Equipment interoperability is a key focus and the company has a vast reference list of established analog systems around the world.

While designing P25 solutions, Tait has ensured a migration patch between analog and digital. The company also contributes to the maintenance and evolution of the P25 standard and constantly participates in APCO P25 steering committee meetings and TIA TR-8 Engineering Committees.

The outlook for P25 as a thriving, living standard looks bright. There are goals to further improve spectrum efficiency in the Phase II implementation of P25 which is still some way from completion.

The user committees, who drive the development of the standard, are in place to ensure, for example, that the benefits of P25 realised in Phase I, such as comparable coverage to analog and backwards compatibility, are not lost in future implementations.

This gives further assurance that P25 is the right standard for the vast remote territories to be covered in Australia and New Zealand.

The spectrum efficiency goals will bring relief to the acute congestion with UHF frequencies in some metropolitan areas in Australia for example.

The benefits of P25 have been harnessed by organisations globally, the continuous investments made by manufacturers in developing new systems and the effort made by standards bodies to improve its efficiency will ensure that P25 is the digital standard for the future.