DMR / Hytera / XPT or Tier3

[patrick211]

Hello,

Please excuse me if I'm at the wrong place for this, I did not find anything suitable to this question.

Here the case:

We are about to setup a Radio Network with 1 permanent static repeater (RD985S).
We have planned 3 additional repeaters for mobiel use depending on events (mainly sport events that cover over 100s of km).
We planned to use Hytera RD985S repeaters (the first 1 arrived yesterday).

We want the users with their devices (Mobile & Portable) to communicate with other subscribers where ever they are independently on which repeater. The repeaters will be IP connected through the GSM network.

We will use up to 6 groups. We currently have 2 permanent UHF frequencies for Digital (DMR) use. Any additional frequency will be acquired temporarly based on events' needs.

Number of final subscribers starts with 30 onwards and no limit.

The question is:
What is the best use and best practice to avoid subscribers to change channels when they get out of range from a repeater and get into the range of the next repeater. I heard about the roaming function. How does this work? Do I need different frequencies for each repeater to avoid overlapping?
Is it an option (good or bad) to have more than 1 repeater per location? What about XPT & Tier III use in this case, usefull?

I also need to say, that for the 1st repeater the Frequencies will be permanent. For the other 3 repeaters, we will get new temporary frequencies every time we need them for an event. They may be the same, but this is not garanteed.

The system needs to be expendable as much as possible, so we are open to any upgradable solution, reason for the RD985S as this is Tier III compatible.

Thank you in advance for any help and suggestions
Kind regards
Patrick

 

[phillmobile]

use mpt1327 with cell extenders, better audio at a fraction of the cost.
The radios will just find the channels and really for range you need vhf not uhf

 

[Project25_MASTR]

Hytera has to have a working Tier III solution first. Everyplace I've seen it be installed, it has failed. Right now the big debacle is a system they sold a municipality in Canada.

Do yourself a favor, if you want Tier 3 and actual support, go with a different vendor.


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[RayAir]

Hytera XPT (eXtended Pseudo Trunk) would be a good option. It is similar to MotoTRBO Capacity Plus.

Enable static authentication to control subscriber units accessing the system. If a SU doesn't have the authentication key in it, it can't access the repeater. There's also dynamic authentication where the key periodically changes, but static should be fine. This feature keeps unauthorized radios from accessing the system.

As far as roaming, you will have to determine your coverage area per repeater and what threshold to use before a radio decides to switch to a site with a stronger RSSI.

 

[Raccon]

The question is:
What is the best use and best practice to avoid subscribers to change channels when they get out of range from a repeater and get into the range of the next repeater. I heard about the roaming function. How does this work? Do I need different frequencies for each repeater to avoid overlapping?
Is it an option (good or bad) to have more than 1 repeater per location? What about XPT & Tier III use in this case, usefull?

You could use the RD985S repater in DMR Tier II mode with pseudo-trunking, so the radio will pick any available channel on the repeater where it is registered. Furthermore the radios can roam to another repeater if the signal level drops below a preset threshold. You will need different frequencies to avoid interference if there is an overlap in coverage.
More than one repeater per location is "good" as it gives you more capacity, however then you will also need a combining system or additional antennas (and different frequencies for each repeater, obviously).

XPT is a proprietary system, so only Hytera radios will work with the RD985S in XPT mode. Not sure that you will need the XPT features for your use case.

Tier III is a trunking system and will be more expensive as you need controllers for each site, a centralized switch and a network management system. Based on your current requirements I can't see that being justified.

 

[Project25_MASTR]

Tier III is a trunking system and will be more expensive as you need controllers for each site, a centralized switch and a network management system. Based on your current requirements I can't see that being justified.

Just for the record, here is a 4 site Tier III system I built out in the testing phases (two sites are in one rack). It's been deployed for nearly a year now. Note no controllers, those only come into play when you go above 25 sites with that equipment.

While we are on the subject it is also worth noting Motorola's Capacity Max only uses one controller on the entire system. Not sure how Hytera handles it…

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[Raccon]

Nice looking system there.

Hytera needs controllers for each base station. A centralized switch is required for more than 5 cells or if more capacity for application clients (NMS, Dispatchers, Voice Recording) is needed.
The controllers and switch are COTS servers, which may also be deployed in a redundant configuration when a centralized switch is used.

Motorola's Capacity Max can only go up to 15 sites compared to Hytera's 50 (with the RD985S). Note that Hytera also has DMR Tier III system based on a different HW platform that allows you to interconnect multiple switches and thus form very large networks with hundred of cells.

 

[Project25_MASTR]

Nice looking system there.



Hytera needs controllers for each base station. A centralized switch is required for more than 5 cells or if more capacity for application clients (NMS, Dispatchers, Voice Recording) is needed.

The controllers and switch are COTS servers, which may also be deployed in a redundant configuration when a centralized switch is used.



Motorola's Capacity Max can only go up to 15 sites compared to Hytera's 50 (with the RD985S). Note that Hytera also has DMR Tier III system based on a different HW platform that allows you to interconnect multiple switches and thus form very large networks with hundred of cells.

Simoco is putting in a 80 site system up in Canada right now. 25 is just the limit without the need of an additional server.

It's a very overly redundant system with each repeater being able to not only be the system server but also be the "Zone Master" (Zone controller) and Site Master (Site controller). Loss of connectivity to the two system controllers on Capacity Max and you are stuck in site trunking system wide. Lose connectivity to a zone master on an Xd system and the system picks another zone master.


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[phillmobile]

Ambitalk have a Tier 4 trunk system if thats of interest

Ambitalk - Reliable communications for commercial vehicle fleets