Subject: [NEXTEL-1] Nextel & Public Saftey

From: [email-masked]
Date: Sat, 06 Dec 2003 15:04:18 -0500

-------- Original Message --------
From: "Rik Rasmussen" <[email-masked]>

Also, note that many Public Safety systems record all or some of the radio
traffic. When the officers talk to each other on Nextel, they don't worry
about later listening to a recording in the chief's office or the Internal
Investigations Office.

Rik Rasmussen
Two Way Radio Directory
http://twowayradiodirectory.com

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From: Rick Parrish <[email-masked]>
Date: Sat, 06 Dec 2003 17:20:32 -0600

There's been some work to accomodate recording of dispatch / iDEN 
traffic. It isn't clear to me whether this extends to unit-to-unit or 
"direct connect". Check your favorite voice recording vendor.

>Also, note that many Public Safety systems record all or some of the radio traffic. When the officers talk to each other on Nextel, they don't worry about later listening to a recording in the chief's office or the Internal Investigations Office.
>
>Rik Rasmussen
>Two Way Radio Directory

---

From: "Rik Rasmussen" <[email-masked]>
Date: Sat, 6 Dec 2003 20:24:30 -0500

That is so a base radio connected to a console can record conversations
between the console and units that it talks to privately or in group call.

Does not involve field units talking to each other privately.

Now, since you bring it up:

Is anyone aware of Nextel allowing any reasonable size agency to use group
call dispatch on their system? If so, who?

Rik Rasmussen
Two Way Radio Directory

---

From: [email-masked]
Date: Sat, 06 Dec 2003 20:28:54 -0500

Oh yea,

I have been implementing iDEN with Centracom golds and TEAC recorders since 1996.Unit to Unit recording has been around for years since CLEA made it a requirement (besides at the switch).

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From: Jack Daniel <[email-masked]>
Date: Sun, 07 Dec 2003 12:30:06 -0800

Rik,

I'd be interested in hearing about agencies that have large calling
groops on Nextel also.

I've looked into this a little and it is my understanding the maximum
'group' size is 25 handsets per group.

And since no one wants the ability to monitor Nextel conversations to
become wide spread, the recording point has to be a handset that is
operating on a one-to-one basis or a member of a 'group', probably
located at the dispatch center.

I have looked at this and perhaps it is too complex to implement and
explain to the agencies that might need real group communications
features.
 
As an example, a moderate sized department using 150 Nextel handsets, it
looks like you have two choices to possibly record all public safety
comms and especially 'group' exchanges;

Approach A. 
Program everyone as one of a 25 member group, with the recording point
being a member of every group. That leaves 24 non-recording point units
per group, so you'll need to set up seven groups. You'll also need 7
recording channels and 7 handsets and 7 interfaces (recorder and
consoles).

Also keep in mind a few other things come bundled with large group
calls;
- The air time usage and charges are multiplied x 25 on every
transmission, regardless of whether the other units are in service or
unable to receive the calls. 

At a $0.15/ minute rate, each minute would cost (25 x $0.15) $3.75/
minute. During an emergency with 75% max air time for 4 hours (240 x .75
x $ 3.75)= $675 per group, times 7 groups = $ 4725.00 in air time
charges or more for this incident.

Approach B:
Keep all the users as individual units and all calls are one-on-one. 
To monitor all 150 units, you'd make each unit and a handset at the
dispatch center a separate 2 unit group. Here the number of handsets and
dispatch interfaces gets complicated fast. 

To be 100% positive that you had every one of the transmission of the
150 handsets recorded would take 150 groups and 150 handsets and 150
interfaces and 150 recorder tracks. You can't assume that the units
transmissions will always be to another handset that's part of the
group; it might be a landline call or to another agency's handset.

One could develop software over time that would all the use fewer
handsets, etc, at the dispatch center, but each assumption that you have
an adequate number of fewer tracks going simultaneously reduces the 100%
value. My guess is 50 handsets and recording tracks would yield about
90% probability of recording all the traffic, but is that good enough in
court?

For airtime let's assume the same scenario as in Approach A; 4 hours at
75% capacity using two unit groups. Each minute is 2 x $0.15 = $0.30/
minute.
Times 150 groups = $ 45 / minute. Times 4 hours (240 minutes) x .75 =
180 minutes x $45 = $ 8100 air time charges for this example.

Although Approach B is much more expensive than Approach A, it does open
the door for advanced dispatch functions. 

The agency can build it's own groups of any size and when they like. By
operating many dispatch handsets in parallel, virtual groups can be
formed as fast as custom software (that need to be developed) could
switch and combine audio and control of the 150 handsets, perhaps a
customized PBX switch with 150 links in it.

There would be some timing issue to resolve since all the handsets in
the group may experience different connect delays, but if everyone is
trained to wait several seconds between pushing the push-to-talk button
and saying anything this would not be a problem. Since the individual
units are in effect cross-patched at the dispatch center, each user
would have to wait for the worse case connect time to be sure other
members of the group heard him. Remember, in true public safety wireless
'groups', everyone in the group hears everything any one in the group
transmits.  

The ability of the agency to control group settings eliminates the 25
unit group limitation and the 4 to 24 hour delay the Nextel network
center may need to make a larger group modification.

If you have all 150 handsets at the dispatch center you will know which
did not respond to a group message and the dispatcher will know to
repeat the message as many times as needed to get it to everyone in the
group.
 
(Some may recognize the ability to build you own groups 'on the fly' as
"dynamic regrouping", a standard feature of public safety P-25 systems.)

Summary;

By adding a lot of equipment at your dispatch center, you may be able to
record Nextel messages.

By adding even more equipment you may be able to work around Nextel's
group calling limitations.

To be most effective, custom software may need to be developed at the
agencies expense.

Air time charges that might cost $4,000 - $8,000 or more per incident is
acceptable as an ongoing expense exposure.

Users may need to be trained to wait several seconds before talking in
group call exchanges.

AND the cell site serving the dispatch center needs to have adequate
capacity to handle ALL the dispatch centers calls (could be 150
talk-channels or 50 RF channels) in ADDITION to handing the traffic load
from other cell site users. 

To be sure, the dispatch center traffic should  be given absolute
highest priority,
BUT that may not be possible if Nextel has already assigned top priority
levels to Federal agencies such as DHS, FEMA, FBI, Customs, DEA,
Forestry, OSHA, etc.

I'm sure the managers and administrators of public safety agencies that
use Nextel (or any other cellular service) for public safety
communications applications examined these and hundreds of other details
when they concluded it was better to spend perhaps millions a year on
service charges than build equity in their own radio system.

But I may be wrong………
Jack Daniel
===========================================

---

From: "Rik Rasmussen" <[email-masked]>
Date: Sun, 7 Dec 2003 15:53:22 -0500

At the recent Wireless Summit in Washington, D.C. I challenged Nextel's
Direct Connect manager to cite a case of a Public Safety agency successfully
using group call. He mumbled something about a Hertz lot at an airport. I am
still waiting for the Public Safety example.

Rik Rasmussen
Two Way Radio Directory

-----Original Message-----
From: Jack Daniel [mailto:[email-masked]]
Sent: Sunday, December 07, 2003 3:30 PM
To: [email-masked]
Subject: Re: [NEXTEL-1] Nextel & Public Safety : To Group or Not Group

Rik,

Approach A.

Approach B:

Summary;

But I may be wrong………
Jack Daniel

---

From: "meijin" <[email-masked]>
Date: Sun, 7 Dec 2003 15:40:28 -0600

Texas Instruments in Dallas, TX. Give them a call. They are using it quite
successfully.

Mike

> still waiting for the Public Safety example.

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From: Don Root <[email-masked]>
Date: Sun, 07 Dec 2003 13:47:49 -0800

> Texas Instruments in Dallas, TX. Give them a call. They are using it quite

I know that the Texas thought process can be different, but when did TI 
become a Public Safety agency?

Don
(.25 Texan)

---

From: [email-masked]
Date: Sun, 07 Dec 2003 18:07:14 -0500

Jack,

The size of the dispatch group is actually determined Metro Packet Switch,
Packet Duplicator and the Advanced Packet Duplicator architecture. The OMC
determines how various resources are deployed. The Packet Duplicators (kind of
like a Xero machine for data) provide the functionality to allow broadcast,
group and multicast operation with dispatch calls. Each packet duplicator has
the processing power to make enough duplicate packets for each EBTS in the
system. The packet duplicator is used to replicate voice and data packet for
output to multiple subscriber units in Dispatch calling and Packet Data
networking. If a dispatch call is to a group, the voice packets from the sender
must be duplicated for output to each of sites hosting a receive unit. Soco's
group call for Birmingham PD (they are now switching to a Private network)
Georgia Power, Alabama Power, etc. is much larger than the measly 25 person
limitation set by Nextel. The limitations are do to Nextel's limited resources.
The Packet Duplicators are monitored by the OMC/R.  Advanced Packet Duplicator
resources are as follows:

Packet Duplicator Limitation Guidelines
Subsystem
APD

 Users
N/A

Sites
 1000
(250/port)

Limiters
2000 simultaneous calls
*Erlangs/subscriber (user) can not exceed Calls/Port limitation

Comment
500 call/port

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From: Jack Daniel <[email-masked]>
Date: Sun, 07 Dec 2003 14:37:38 -0800

Good one, Mejin.

Did some Nextel salesman tell you T.I. was a public safety agency?
They don't seem to know what one really is or how they operate.

============================================

meijin wrote:
> > using group call. He mumbled something about a Hertz lot at an
> airport. I
> am
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From: "Rik Rasmussen" <[email-masked]>
Date: Sun, 7 Dec 2003 19:22:54 -0500

I said Public Safety agency.

I have heard anecdotal stories of Nextel arranging for commercial users to
use group call in a limited area, but have yet to hear of a case of a Public
Safety agency using it throughout a city or county in group dispatch mode.

Rik Rasmussen
Two Way Radio Directory

-----Original Message-----
From: meijin [mailto:[email-masked]]
Sent: Sunday, December 07, 2003 4:40 PM
To: [email-masked]
Subject: Re: [NEXTEL-1] Nextel & Public Safety : To Group or Not Group

Mike

---

---

From: Jack Daniel <[email-masked]>
Date: Sun, 07 Dec 2003 21:20:39 -0800

Thanks Marcel. 
Seems the technology camn do a better job with grouping than Nextel is
advertising.

I guess that means Nextel has other reasons for limiting group usage. 
Could it be that to do so would degrade non-public safety service or
impact revenues?

Assuming Soco is providing larger group service, how much do they
charge?

===================================================================

[email-masked] wrote:
> networking. If a dispatch call is to a group, the voice packets from he sender
> must be duplicated for output to each of sites hosting a receive unit.
> Soco's group call for Birmingham PD (they are now switching to a Private
> network) Georgia Power, Alabama Power, etc. is much larger than the measly 25
> person limitation set by Nextel. The limitations are do to Nextel's limited
> resources. The Packet Duplicators are monitored by the OMC/R.  Advanced Packet
> Duplicator resources are as follows:
>

---

From: [email-masked]
Date: Mon, 08 Dec 2003 01:05:59 -0500

> Seems the technology camn do a better job with grouping than Nextel is

It's all about the resources. Nextel does not have enough to support numerous wide
area group calls at the same time.

> Could it be that to do so would degrade non-public safety service or

They don't want to overload their system.
I have not done the math but large group calls could limit one-on-one calls.

> Assuming Soco is providing larger group service, how much do they

Sorry I'm don't know about pricing maybe one of the SoCo guys could answer up.

---

From: "Neil Horden" <[email-masked]>
Date: Mon, 08 Dec 2003 13:44:14 -0000

Some of these limitation might have been put inplace in teh early 
days when the packet duplicator did have a limitation.

By the way, the limitation (then, don't know if it still applies) was 
on teh number of SITES that could be included in a group call, not 
specifically the number of UNITS.

--- In [email-masked], Jack Daniel <JackDaniel@R...> wrote:
> Marcelrf@B... wrote:

---

From: "meijin" <[email-masked]>
Date: Mon, 8 Dec 2003 08:28:01 -0600

Don:

I never said that TI was a PS agency. What I said was that they should be
checked out. They have a very interesting solution that overcomes alot of
the limitations being discussed for their own huge first responder groups as
well as being tied directly into the local FD and PD groups.

And thank you no Jack....no Nextel salesman told me anything. TI happened to
be my customer when I worked in a different part of Nextel. As I said, for a
group call situation that might be of interest, you should check them out
instead of tossing out insults.

Mike

----- Original Message ----- 
From: "Don Root" <[email-masked]>
To: <[email-masked]>
Sent: Sunday, December 07, 2003 3:47 PM
Subject: Re: [NEXTEL-1] Nextel & Public Safety : To Group or Not Group

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From: [email-masked]
Date: Mon, 08 Dec 2003 09:26:34 -0500

> specifically the number of UNITS.

See limitations below-

---

From: Jack Daniel <[email-masked]>
Date: Mon, 08 Dec 2003 07:34:14 -0800

OK Meijin, I'm willing to learn. 
Can you post some details about the TI Nextel group diapatch system?

==============================================

---

From: Jack Daniel <[email-masked]>
Date: Mon, 08 Dec 2003 07:41:04 -0800

Thanks Neil. 
I think a lot of people are interested in what the system can and cannot
do. There's too many generalizations being tossed around on this subject
that might gloss over a serious shortcoming. On the other hand there may
be something really neat that no one knows about.
===============================================

---

From: "Neil Horden" <[email-masked]>
Date: Mon, 08 Dec 2003 15:14:24 -0000

I don't see a specification for sites per call.

In the '94 to '97 time frame, the limit was caused by the ammount of 
time the MPS/PD took to create and distribute the duplicate voice 
packets vs. the amount of time allowed to set up a call.  (From my 
understanding)

---

From: [email-masked]
Date: Mon, 08 Dec 2003 18:40:14 -0500

> I don't see a specification for sites per call.

The nominal limitations for iDEN systems are based on the available hardware and
the
localized traffic.

Take a look at  iDEN S.E.T.S Group Formulas for Traffic Analysis, MSO Timing
System
(sysiu020 r12) and the MSC Subsystem General Planning and Expansion manual.
If you don't have the hard copy you can get them on-line at the iDEN support
website, AccessSecure.