Measuring Communications System Performance: What's the Norm

[ahawkins]

Hi there. I am trying to get an idea on how data performance is measured over a trunked digital radio system. I came across this information on some technical website. It is listed below, talking about a given message model, and was wondering if this was a valid method of testing a digital/data system. The table is also listed in an attached file as well. I was also curious if there were any other methods of testing data system performance on a trunked system, that are used by the major vendors (ie Motorola, MA/COM, LTR, etc). I am trying to get an idea of how this is done in the industry, to include in a paper that I am putting together on digital radio systems. Thanks.



Using raw data bit rate to compare data systems can be very misleading. The actual system performance depends on a variety of factors including the protocol efficiency, signaling conditions, system loading, and the particular application being used. The true measurement of a public safety data system is the number of users the system can support with specific applications. This information is typically provided in a message model similar to the one shown below. By requiring each vendor to define the number of users a channel can support with a specified message model, a customer can make a true comparison of the data system’s performance.

Example Message Model for Law Enforcement.

Message Inbound (to Base) Outbound (to Mobile)
Bytes msg/usr/hr Bytes msg/usr/hr
Login 253 1 185 1
LP Inquiry 193 5 256 5
Email with
Confirmation 386 3 212 3
DL by Number 186 2 225 2
DL by Name 162 2 232 2
Changing Status 148 6 52 6
Changing Status
Broadcast 10 chan 0 0 148 60
CAD Query 196 5 226 5
Log out 172 1 74 1
CAD-to-car 50 1 200 1
Field Report 7000 0.5 3000 0.5
Mug shot 250 0.5 7000 0.5
AVL 40 12 75 12

 

[N_Jay]

I would guess that most here have never seen a message model.

The model does not look bad, but there is lots of room for error.
I would want to know where the numbers came from and how realistic they are for teh particular system.
If it is a multi-channel or multi-site system then there are other issues which must be addresses.

I would ask this question on one of the Public Safety users discussion forum.

 

[ahawkins]

N_Jay

I was wondering if there are any other forums here at Radio Reference that you would suggest posting this system information. Also, do you know of any other Public Safety forums that are external to this website that I could go to asking the same questions? I have been having a hard time finding forums and sites such as the one you speak of. Thanks.

 

[N_Jay]

N_Jay

I was wondering if there are any other forums here at Radio Reference that you would suggest posting this system information. Also, do you know of any other Public Safety forums that are external to this website that I could go to asking the same questions? I have been having a hard time finding forums and sites such as the one you speak of. Thanks.

There are a few Yahoo Groups.
Do a search.
Good search words are;
APCO
LMR
PSMR
Project25
Smartnet
Trunking.
SIEC
Mobile Data