What I know so far...
Well... I did a lot of reading to try to understand how the system is
setup. As I used to have to deal with trunking systems [in a previous
life] I understand talkgroups and the problems with having too many
available without the channels to support them all when you have
simultaneous use. DMR is no different. Throughout the world I see many
different thoughts on how to allocate the talkgroups to make many
options for the users without completely killing the system. Some
groups do it well, others... well, I'm not sure how their systems can
even work.
They systems in the Mid-Atlantic seem to do well. I'd probably make
some adjustments but overall they seem to run smoothly. The repeaters
seem to have "local" on one timeslot and everything else on another.
That keeps local open all the time for conversations. This is in
contrast to the NC PRN network which lumps local onto a timeslot with a
bunch of "on-demand" talkgroups.
Their system-wide talkgroup, PRN, is kept on its own timeslot without
interference. Again, it's all about priorities.
The system's efficiency is at risk when you put too many users on too
many talkgroups, especially when those talkgroups occupy timeslots on
all the repeaters all the time. Of course someone thought of this and
created
TAC-310;
an on-demand talkgroup that most everyone (globally) has access to but
doesn't occupy a timeslot on a repeater unless it's been activated
there. Makes sense, correct? You can get off the calling channel and
get over on a discrete channel that doesn't utilize that many
resources. Unfortunately there is only one of these talkgroups. Even
on a system the size of NC PRN their get-off-of-PRN talkgroup is named
'Southeast' where the talkgroup has many more potential off-network
users. Still it's all about priorities and fulfilling a certain
mission.
CalDMR seems to have a good way of separating communications onto their
timeslots.
I guess the hope is that you won't have too many conversations at each
level happening simultaneously.
One system I've been quite impressed with the Connecticut's DMR ARES
system. Designed to facilitate
intra-state communications, they have added ten tactical on-demand
tactical
channels
to help spread out the load away from system-wide channels while
supporting many simultaneous communications. Still, I wonder about the
load and whether or not the repeater congestion will be a problem.
Most of these networks are young and I suspect some shifting around will
be required on all networks as well as an understanding of the
priorities of the network by its users.