Let’s get going on P25’s next phase
The recent decision by the Project 25 (P25) Steering Committee to select TDMA as the basis for Phase 2 of the standard gives the industry a much-needed path forward to making P25 Phase 2 systems a reality. What remains is an especially critical series of next steps in order to create a solid foundation to build next-generation technologies.
There has been tremendous progress towards interoperability with P25 Phase 1 systems. More than one million P25 subscriber radios from at least a dozen suppliers have been deployed nationwide. Thirty-one states have deployed, or are in the process of deploying, statewide networks. The industry’s next imperative is to leverage additional technologies for P25 Phase 2 development efforts while simultaneously meeting a broad range of customers’ needs.
Taking care of public-safety customers means having the ability to deliver many different types of solutions to fit a variety of customers’ needs. There are customers who want TDMA right now and others that want to be able to leverage the technology in the future after Phase 2 is finalized. In addition, vendors have to strongly support Phase 1 FDMA customers who may never want TDMA.
While there has been much progress on P25 standards, lots of work still needs to be done to ensure that customers’ requirements for interoperability are met. The TDMA Task Group indicated that the documentation for the Phase 2 air interface will take 24 months to complete, and an additional three months will be needed for the TIA to review, comment, ballot and publish the standard. Only then will manufacturers have a completed standard upon which products will be developed and shipped.
Despite all of the work that remains, it is encouraging to see that the P25 committee is making progress towards satisfying the ever-increasing demand from public-safety customers for spectrum-efficient solutions. Others in the industry should be committed to the P25 interoperability standard and embrace the next stage of work on the harmonized Phase 2 TDMA solution. The faster this process moves, the sooner we can all get compliant products into customers’ hands.
Sorting out the complexities and technical challenges within this next stage of standards development is critically important. This process involves many details and often technology trade-offs are made along the way to the completed standard. But there are three areas where there can be no trade-offs: RF interference; forward-backward compatibility; and maintaining the current coverage footprint without requiring additional towers.
Our analysis of the Phase 2 TDMA air interface revealed that the RF performance of the harmonized solution may be susceptible to adjacent site interference — especially in urban areas. Interference in public-safety communications systems simply is unacceptable.
Customers also need to have the ability to interoperate with, or migrate from, current systems as they build out next-generation solutions based on P25 Phase 2 standards. This requirement can be met by providing forward-backwards compatibility between Phase 1 and Phase 2 systems.
Also, manufacturers must allow for simulcast with the same number of sites. Technologies that require additional towers to achieve the same coverage footprint not only add cost, but also slow the migration to Phase 2, as siting, permitting and building new towers takes time and additional resources.
Motorola is committed to the P25 standards-development process and we look forward to the significant benefits to public safety that will come from broad deployment of next-generation, standards-based solutions. The P25 steering committee has given manufacturers a clear path forward and it’s now up to all in this process to resolve these outstanding issues. Let’s get going.
Bob Schassler is vice president for Motorola’s government and commercial markets division.
