A new era for interoperability

By Bill Pagones

Attendees of public-safety trade shows and conferences often see interoperability demonstrations.  After all, the essential need for interoperability has been widely recognized for more than a decade.  But those who visited the Project 25 Technology Interest Group (PTIG) booth at the International Wireless Communications Expo (IWCE) earlier this year were heard to say, “I can’t believe what I am seeing,” and “That is astounding.”  What they saw was the first-ever multi-vendor P25 Console Subsystem Interface (CSSI) and Fixed Station Interface (FSI) interoperability demonstrations.

The PTIG sponsored this unprecedented event featuring the consoles, radio subsystems and fixed-station equipment of 12 different manufacturers, all located in a single 20’ x 20’ booth.  Over a period of two days, during eight scheduled demonstrations, these PTIG members showed 19 different combinations of equipment interoperating with each other. The participants included five console manufacturers (Avtec, Catalyst, ModUcom, Pantel and Zetron), and seven radio subsystem manufacturers (Cassidian, Codan, Harris, Motorola, Relm, Simoco and Tait). In addition, three other companies helped to facilitate the event by aiding with marketing and technical setup: Cisco, Cynergyze and Etherstack.

The PTIG has sponsored other interoperability demonstrations during the past decade.  These included Common Air Interface, or CAI, interoperability, and Inter-RF Subsystem Interface, or ISSI, interoperability.  This recent demonstration by far had the largest participation, both in terms of the number of manufacturers, and the scope and diversity of active equipment.  This shows the maturity of the P25 wireline interface standards (CSSI, FSI), and the willingness of manufacturers to adopt the P25 standards and to cooperate with each other to ensure the success of the standard.

The published Telecommunications Industry Association (TIA) P25 wireline interface standards—the CSSI for trunked P25 systems and the FSI for conventional P25 systems—were central to the demonstration.  Among international narrowband radio standards for public safety, Project 25 stands alone in that its standardized interfaces go beyond air and peripheral interfaces to include key Internet Protocol (IP)-based wireline interface standards for fixed network equipment (FNE). This allows users to choose the best-of-class equipment from among the numerous P25 console and RF subsystem (RFSS) manufacturers. This reality of multi-vendor sourcing fulfills the promise of P25 to achieve increased competition and thereby drive down the price of such equipment. It also provides the unique solutions required by individual public safety, utility, federal and other critical-communications agencies. 

Although the CSSI and FSI published standards are not new—the core documents of those standards were published in 2006—it has taken a few years for a critical mass of manufacturers to adopt them. Last year was a turning point, as several additional manufacturers added CSSI and/or FSI to their offerings. This is not to say that the CSSI and FSI are just now being deployed; among the vendors offering CSSI, at least one has more than 1 million console-hours of CSSI operation in the field.

While many critical-communications agencies find the current standards more than adequate for their needs, the features supported by today’s CSSI and FSI will be expanded in the future. P25 standards are considered “living” in the sense that as new user requirements are identified, or as existing requirements are incorporated, the standards are updated periodically by TIA’s TR8 engineering committee to support these new capabilities. The CSSI standard has been through several updates during its life, the most recent of which was published last December (TIA 102.CABA-B), which added support for P25 Phase II (TDMA). Similarly, the FSI standard (TIA 102.BAHA) is presently being updated by the TIA and is expected to be republished late this year.