Key issues to consider when switching to digital

steamgloomyElectronics - Devices

Nov 15, 2013 (3 years and 7 months ago)

56 views

Key issues to consider when

switching to digital




January 2012

Going digital


12.5 kHz DMR or 6.25 kHz FDMA?



Two of the most important reasons that LMR users go digital are to

add voice capacity and to more easily add data applications




This presentation sets out the important issues for the user to think

about


Adding capacity


12.5 kHz DMR or 6.25 kHz FDMA?

Adding data applications nearly always means that more capacity is
needed to ensure:



Existing voice quality of service is to be maintained and



The new application is to work well


There are real differences between DMR and 6.25 kHz FDMA when it
comes to increasing capacity in terms of:



Spectrum efficiency is existing licenses



Infrastructure requirements


Digital migration in existing 12.5 kHz licences
-

DMR

Analogue to digital migration with DMR


Existing analogue talk paths in a 12.5 kHz
license


New digital talk paths in your 12.5 kHz
license


Double capacity in current license?

Digital migration in existing 12.5 kHz licences
-

FDMA

Analogue to digital migration with 6.25 kHz FDMA


Existing analogue 12.5 kHz

license


New digital talk paths

In 12.5 kHz license


Double capacity in current

license?

Spectrum efficiency
-

DMR and 6.25 kHz FDMA

Existing analogue 12.5 kHz

licence


New digital channels


6.25 kHz spectrum efficient?

New channels fit legacy devices?

No

risk of new interference issues?

DMR Migration


6.25 kHz FDMA Migration


Spectrum use
-

DMR vs 6.25 kHz Migration



Because DMR uses the same 12.5 kHz channels as analogue


co
-
existence between analogue and digital is simple



Ease of migration



Ease of long co
-
existence between analogue and digital

Going digital DMR and 6.25 kHz FDMA licence summary

Going digital with DMR means:



Doubling capacity in existing licenses



Keeping existing spectrum



No new frequency co
-
ordination requirements



Being able to continue to use legacy analogue radios in your spectrum



No new risk of interference as the channel characteristics stay the

same and proven 12.5 kHz signals are maintained



Use of infrastructure: DMR compared to 6.25 kHz FDMA

Migrating from one

channel DMR to two

channel DMR:




No extra complexity



No extra cost



Power efficient



No extra space



No new site issues



No extra maintenance


One channel DMR


Two channels DMR



Use of infrastructure: DMR compared to 6.25 kHz FDMA

Migrating from one channel
FDMA to two channel FDMA:


Extra complexity

Extra cost

Greater power use

More space

Potential site issues

Extra maintenance


One channel 6.25 kHz FDMA



Two channels 6.25 kHz FDMA


DMR advanced features


not possible with FDMA


Advanced control features through reverse
channel signalling


System flexibility through simultaneous voice
and data calls, two way calls, double data rates
enabled by two slot TDMA


Power efficiency of DMR compared to 6.25 kHz FDMA


Two slot TDMA structure means transmitter



is used 50% less than with FDMA


This means DMR radios are more power efficient than
FDMA and give greater battery life/unit of battery capacity


Significant with data applications


Adoption of DMR technology today


There is a strong supplier base of DMR


Over 1,000,000 DMR 2
-
way radios are in operational use


DMR manufacturers support a robust and established vendor
interoperability testing programme

Summary

When you switch to digital:



Understand the real differences in the technology that is on offer



Understand the license implications



Understand the infrastructure requirements today and tomorrow



Understand the strength of the DMR supplier base



Make the smart choice