Looking at...


operators, the decisions they make now will be critical to their future success. While migration to the latest


Migrating to DMR T


he time for DMR has come and choice is in- creasing – but, for many


• interoperability through a well defi ned and managed process. T e DMR standard comprises


technology usually delivers an enhanced user experience, it can present signifi cant logistical chal- lenges for system owners as they strive for minimal operational downtime during the migration period. Migrating to DMR brings to


the PMR world all the benefi ts of digital technology that we have seen in cellular, business VoIP and high-end public safety radio technologies, in a cost-eff ective, manageable package for business- critical and mission-critical appli- cations.


Benefi ts of digital DMR is an ETSI standard de- signed to deliver a number of tan- gible benefi ts, including – • re-use of existing 12·5 kHz licensed channels but with double the capacity;


• backward compatibility with legacy analogue radio systems;


• effi cient use of infrastructure; • greater power effi ciency and longer battery life for terminals;


• simultaneous voice and data calls;


• digital audio quality; • data services for applications;


three tiers, two of which are tar- geted at professional radio users. Tier II DMR provides conven- tional mobile radio features and Tier III DMR defi nes trunked radio operation. Manufacturers off er a wide


variety of systems which are compliant with the DMR Tier II standard. Tier III equipment will become available in 2012 – but in order to maintain the freedom to choose suppliers, it is essential that network operators use fully- compliant Tier III equipment.


Market moves T e introduction of DMR has brought a signifi cant and grow- ing adoption of the technology for small systems which are suited to Tier II DMR. T ese are mainly new radio systems, where starting with a digital radio scheme is at- tractive, or replacements of small legacy analogue conventional systems where backwards com- patibility is a major advantage for migration. T e ability of DMR equip-


ment to work in an analogue 12·5 kHz mode makes it easy to deploy DMR equipment on to an existing analogue radio system without negative impact and then to switch over seamlessly to take advantages of the digital benefi ts


About the author


Andy Grimmett is chief technologist of Simoco Group, which is currently introducing its fi rst range of DMR products


once all the legacy equipment has been replaced. However, in larger, multi-site


systems, takeup of DMR has been signifi cantly slower, for a number of reasons. Firstly, a large PMR system is a long-term investment and typically expected to deliver a service life in excess of 10 years. T erefore the advent of a new PMR technology has little impact on the buying cycle of large or- ganizations which are controlled by long-term budgets and the serviceability of the currently in- stalled system. Secondly, larger systems tend


to require a level of systems intel- ligence for subscriber and resource management which can only be delivered by trunking systems, and manufacturers have not yet released DMR Tier III systems to the market. Finally, the standard of com-


munications required by these larger systems often leans towards the mission-critical – such as in providing essential communica- tions for electricity utilities dur- ing a ‘black start’ scenario. It is therefore natural that such orga- nizations choose not to be at the bleeding edge of technology, pre- ferring to see such systems proven fi rst in less demanding environ- ments. T e decision to transfer their trust from the reliable system upon which they have depended for many years to a new platform will justifi ably be based on dili- gence.


Reasons to migrate Despite the expectation that it will take many years for large PMR networks to be migrated over to DMR, there remain some com- pelling reasons to adopt this new technology as analogue systems


34


With its enhanced performance and the promise of lower lifetime costs, DMR represents a compelling proposition for most users, says Andy Grimmett


come to their natural end of life. Probably the most signifi cant


advantage of DMR enjoyed by both operators and regulators is the ability to re-use existing 12·5 kHz spectrum to carry two usable TDMA timeslots, ef- fectively delivering double the frequency effi ciency of the ana- logue system being replaced. For operators, this can mean a com- bination of reduced licence costs and increased communications bandwidth and for regulators it will ease the perennial problem of spectrum congestion without pre- senting the additional headache that other digital technologies bring with frequency re-mapping.


Questions Critical questions to ask when considering migration will be: • Is the proposed system fully DMR compliant through to Tier III?


• Does the proposed use depend on proprietary functionality which may restrict my choice of supplier in the future?


• Does the proposed system functionality support my current ways of working?


• Does the proposed system introduce more complexity in terms of architecture, spares holding and system build?


• How will operational disruption be minimized during the migration process? For current users of business-


critical trunked systems such as MPT, DMR systems will off er signifi cant benefi ts, both opera- tionally and fi nancially. Provided these issues are addressed early on in the choice of supplier and sys- tem, migration from existing sys- tems need not present signifi cant operational risk.


LAND mobile January 2012


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