Subject: [NEXTEL-1] Re: Is it possible for the iDEN system be used on VSAT platform?

From: Marcelrf <[email-masked]>
Date: Wed, 18 Feb 2004 13:28:59 -0500

Craig McCaw (ICO- mobile satellite service ) and Motorola have been
working on integrating  his satellite network with
iDEN. Craig claims that he can use his network to provide "Global
Dispatch" using ICO's network. VSAT presents a few
challenges. As you know VSAT satellites are located approximately 23,000
miles above the equator. A dispatch call
round-trip transmission would  travel 23,000 miles to the satellite,
23,000 miles from the satellite to the remote site, and then
as the data acknowledgment is returned, another 46,000 miles on the
return trip. That's a total round trip of about 92,000
miles.

Even at the speed of light, this accounts for more delay (in
milliseconds) than found in a terrestrial network. Each time a data
packet is handled by a device along the path ( “hop”) several
milliseconds of latency are induced.  Timing is a critical issue to
assure the proper transfer of voice and data calls between iDEN sites.
To assure proper processing, each site must have
highly accurate time information to provide a timing offset to adjust
for the signal propagation time across the network. The
EBTS's use a common GPS timing pulse.

Since voice and data information could use different paths to travel
across the networks the data would have to be adjusted
for time-delay based on the route the data traveled. If control
information takes a longer path than the data or voice
information, there would be a mismatch of information at the
destination. Now this is nothing new Moto has been working to
compensate for additional delays.

Can iDEN tolerate this in its current configuration? Yes, but site
timing may produce some unwanted results. Engineers at
Moto have said that iDEN latency could be as much as 2.5 seconds using a
satellite network, however I'm certain that if
ICO/Motot deploy global dispatch the delays will be minimized.

I see several  major obstacles:

     Bandwidth / Capacity
     Pleisiochronous Timing
     Isochronous Timing
     Reliability
     Cost

I'm not a VSAT expert so I'm sure others will have some insight to share
on this topic.
Do some DD on ICO and see what they have been up to. Check the US patent
office for any new developments.

Mark Hernandez wrote:

  Hi,

  I would like to seek technical assistance from you guys who are expert
in
  Nextel System. Is it possible for the iDEN system be used on VSAT
platform?
  Is there any limitations doing this? I am proposing with Next Mobile,
Inc.
  (Phils) the possibility of using their iDEN on our satellite capacity.
Is
  there an issue in on the latency on the dispatch call?

  Thanks,

  Mark Andrew Hernandez
  Technical Integrator

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