Subject: RE: Moving Targets

From: "Smith JR, Harry E" <[email-masked]>
Date: Mon, 02 Oct 2000 10:57:58 -0700

I am not sure that LEO are a good answer.  Have you thought about how many
satellites you will need.  I would guess around  5 or 6 in the orbit trace.
The second problem will be the handover of the data between the satellites.
This means either cross links or a single hub that all satellites can see
and the routing is on the ground.   A third concern would be that
utilization.  Most of the time they would not be over Australia.

A better idea would be a set of towers along the route like 3rd generation
mobile system.  While the standards only give 2Mbps for fixed station unless
you are talking about a bullet train, I think they could be considered as
stationary.  It will take a little thought. 

Depending on the services offered, you might be able to use part of a GEO
transponder to feed the 3rd Gen Mobile from a single access point. 

Harry Smith 
Lockheed Martin Mission and Data Services
408 - 473 6491

> -----Original Message-----
> From:	[email-masked] [SMTP:[email-masked]]
> Sent:	Friday, September 29, 2000 10:51 PM
> To:	[email-masked]
> Subject:	Moving Targets
> 
> Hi,
> 
> I'm doing a research project about providing Internet access to moving
> targets on the eastern seabord of Australia. In this case, the moving
> targets are trains.
> 
> We really need to provide around 1MB or so downstream, maybe 56k or so
> uplink. I've been doing a lot of searching but facts seem to be hard 
> to come by.
> 
> By my reckoning something like a link to an LEO constellation is 
> needed to make this work because:
>         - GEO satellites can't easily provide this type of bandwidth
>         - GEO satellites require reasonably large dishes and need to
> fairly precisely targetted at the sat
>         - Line of sight is needed for GEO links to work
> 
> Basically, I'm hoping that with LEO links a dish won't even be 
> required, some sort of antenna? Do any of the currently existing LEO 
> constellations provide this sort of service? Future ones?
> 
> Am I completely barking up the wrong tree here? Is there a better way 
> of providing reasonably high speed internet access to moving vehicles 
> without cabling etc.
> 
> Thanks in advance,
> Shaun

---

From: "Dani I. Widjanarko" <[email-masked]>
Date: Tue, 3 Oct 2000 07:03:57 +0700

I don't think that LEO is a good solution, may be you can try to use HAPS
(High Altitude Platform System) that now being explored by many countries.

-dani-

---

From: Schmidt Bill-P26792 <[email-masked]>
Date: Tue, 3 Oct 2000 13:17:40 -0700

I think your remark about Motorola are not only untrue but out of place in
this forum.

bill schmidt

-----Original Message-----
From: Peter Sterling [mailto:[email-masked]]
Sent: Tuesday, October 03, 2000 12:22 PM
To: Smith JR, Harry E
Cc: [email-masked]
Subject: Re: Moving Targets

Harry

The thing that killed Teledesic was a company called Motorola and a grossly
overpriced, no-bandwidth project called Iridium.

Your cell phone hands-off as you move around with no problem and a LEO
system can do the same with no technical problems.

The LEO satellite is in view of any one spot for around 10 minutes so the
hand-off issue is probably less than for a terrestrial system.  The primary
advantage of LEO is the lower power requirements to connect, hence smaller
antenna possibilities. Also it costs one quarter the price per lb to put a
satellite into LEO than GEO. Add the power advantage to the cost advantage
and a global broadband LEO system can give 400% increase in available
bandwidth per $ over a global GEO system, and there's no 1/4 second delay
associated with LEO.

Despite what the GEO crowd believes, because of the latency issue, power and
LEO cost advantage, its probable that ten years from now LEO systems will
make up half of the satcom market.

Teledesic currently has a GEO-Type fixed LEO architecture with stupendous
capital costs and high technical risks, which indicate that it may not be
built in its current form.

Peter Sterling

----- Original Message -----
From: Smith JR, Harry E <[email-masked]>
To: Sat TCP mail list <[email-masked]>
Sent: Tuesday, October 03, 2000 7:49 AM
Subject: Moving Targets

> ( I think this was one of the things that killed Teledisc)
>
> --------------------------------------------------------------------------
--
> -
> 408 473 6491

---

From: "Smith JR, Harry E" <[email-masked]>
Date: Tue, 03 Oct 2000 14:31:34 -0700

Agree that the cellphone hands off with no problem using because of a
coordination between the BST and MST via terrestial lines.  I am not sure
that this is possible for LEO unless you have satellite cross links. 

The power advantage may be offset by the complexity of the terminal antenna
system.  In a cell phone terminal the antenna is omni, for a leo a
directional is needed.  This means either a fast tracking antenna and
aquistion or two tracking antennae. 

As for the cost, the advantage is eaten by the additional satellites needed
to allow continuos coverage.   I think that is a wash.

Harry

> From:	Peter Sterling [SMTP:[email-masked]]

---

From: "Brooker, Ralph" <[email-masked]>
Date: Wed, 4 Oct 2000 15:51:17 -0500

It's not exactly using the tracks, but Andrew has provided many
communications systems for rail networks using Radiax (R) radiating coaxial
cable laid alongside the rails.  The cable has slots tuned for specific
bands such as VHF, cellular, GSM, or PCS, and has a tapered radiation loss
characteristic to give even signal strength along the line.   Every so often
you put a repeater or network access point.  Most of these systems have been
in underground metro tunnels, such as in Hong Kong where commuters talk on
their GSM phones through this network.  However, it does get rather
expensive for a network hundreds of miles long, and the unusual propagation
and fade charateristics can limit the bandwidth. 

Ralph

-----Original Message-----
From: Charlie Younghusband [mailto:[email-masked]]
Sent: Wednesday, October 04, 2000 10:26 AM
To: Andreas Timm-Giel; [email-masked]
Subject: Re: AW: Moving Targets

At $7 US/minute @ 64kbps, that's $420 /hr @ 64kbps or 6720 US $ / hr @
1Mbps.
Plus hw & ISP costs for down under.  Yikes.  Your research project could end
pretty quickly with an Inmarsat type solution.

Want a real research project?  Find a way to send the signal through the
train
tracks.  ;)  Only way to really fix the tunnel problem!

Seriously though, I'd talk to some of the wireless providers in Australia.
Australia is quite advanced at digital wireless services, they might be all
over
an additional excuse to expand their east coast network where most Aussie
cities
are anyway.

Charlie

Also note that a 1Mbps downstream and a 56 upstream probably isn't a good
matchup (an offhand guess); even if you're doing 100% downloading of files,
your
upstream bandwidth could quickly become the bottleneck just with ACKs
assuming
normal windows TCP/IP.  Something closer to a 10 to 1 ratio might be more
appropriate.  Check some of the litterature regarding assymetry and TCP/IP.

Andreas Timm-Giel wrote:
Second problem for L- and

> S-band systems will be the prices for capacity on satellites (just as a
> reference: Inmarsat takes around US$ 7 / min for a 64 kbit/s link)

> > uplink. I've been doing a lot of searching but facts seem to be hard

Charlie Younghusband
Network Systems Engineering
Xiphos Technologies    http://www.xiphos.ca/
514-848-9640           (f) 514-848-9644

---

From: Alex Tosheff <[email-masked]>
Date: Wed, 04 Oct 2000 16:44:34 -0700

Wouldn't a "leaky wire" solution magnify the multipath probs? Especially 
for a moving target?

---

From: [email-masked]
Date: Mon, 9 Oct 2000 09:40:58 +0530

Hiya,

[charlie]
[deleted]

Want a real research project?  Find a way to send the signal through the train
tracks.  ;)  Only way to really fix the tunnel problem!

Seriously though, I'd talk to some of the wireless providers in Australia.
Australia is quite advanced at digital wireless services, they might be all over
an additional excuse to expand their east coast network where most Aussie cities
are anyway.

[abheek]

Actually, I was discussing this with my father just yesterday. He is an
electrical
engineer. The continuous leakage into the ground from the tracks would make it
pretty
unviable, in his opinion.

Regards,
Abheek

---

From: "Smith JR, Harry E" <[email-masked]>
Date: Thu, 12 Oct 2000 07:42:43 -0700

While the concept of HAPS is interesting, I am not sure that I agree with
the economic arguments.  All of the early HAPS were not economical when one
include the life cycle costs. 

Do you have any information on vendors and their projected life cycle cost
for HAPS.

Harry

> From:	Sing Lin [SMTP:[email-masked]]
> Sent:	Thursday, October 12, 2000 6:28 AM
> To:	Smith JR, Harry E; Sat TCP mail list
> Subject:	RE: Moving Targets
> 
> Shaun:
> 
> With proper engineering, one may use the terrestrial 3G IMT-2000 wireless
> systems in the densely populated area to serve the moving train and use
> the
> HAPS in the rural, low population density areas to serve the moving train.
> 
> In densely populated areas, there are enough subscribers to justify
> deployment of terrestrial 3G IMT-2000 systems, whereas in the rural, low
> population density areas, it is more economical to deploy HAPS. Since
> terrestrial 3G IMT-2000 systems will not be deployed in rural areas, there
> is less possibility of radio interference problems for HAPS to operate in
> the 2 GHz IMT-2000 frequency bands in the rural areas.
> 
> Sing Lin
> ***********
> 
> Abheek:
> 
> In addition to the 70 GHz band allocation for HAPS, the proponent of HAPS
> also proposed HAPS for the 2GHz band allocated for the 3G IMT-2000
> wireless
> systems. Substantial work have been done on the frequency coordination
> criteria and coordination distance to make sure that HAPS and terrestrial
> and satellite based 3G IMT-2000 wireless systems will not interfer with
> each
> other. Therefore, under suitable conditions, HAPS may operate in the 2 GHz
> IMT-2000 bands.
> 
> Sing Lin
> ***************
> 
> Shaun:
> 
> USA, Japan and Europe have been doing substantial R&D on High Altitude
> Platform Station (HAPS) in recent few years. The technical contributions
> from these R&D sources to ITU-R WP8F/TG8/1 in the last two years have
> resulted in a Preliminary Draft New Recommendation (PDNR) and a Draft
> Handbook on HAPS in ITU-R WP8F working on the Third Generation (3G)
> wireless
> technologies and beyond. Therefore, HAPS is a serious project and
> technology
> to consider. Each platform is at about 21 Km above the ground and can
> cover
> a very large area.
> 
> Sing Lin
>