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Satellite phones are ringing across the African skies
Source: Africa News Service
Johannesburg - Satellite systems are becoming increasingly accessible
and useful, writes David le Page
Satellite telephony is about to hit South Africa, or at least the
wallets of those wealthy enough to afford it. Iridium has signed a
non-exclusive agreement with MTN.
Vodacom will be offering customers access to both the [Globalstar] and
Iridium services, though Globalstar will be its primary offering. This
may be because Vodacom's United Kingdom partner, [Vodafone], has a 7,5%
stake in Globalstar.
How does satellite telephony work?
When you, Jonas Savimbi, are sitting in the Angolan bush making a
satellite call, there will be four components to the system you use that
will determine the speed, reliability, capacity and cost of your call.
These components are the satphone, the satellite network, the satellite
ground stations and the terrestrial phone network. Your satphone call
goes up to the nearest satellite in your network, and from there back
down to a ground station.
Sometimes, and this is one of the technical advantages of the Iridium
network, the call will be bounced from satellite to satellite across the
sky before dropping to the ground station nearest your call's final
destination. This technical advantage is a political disadvantage, as
fees for bypassing all the countries on the ground have to be negotiated
with them.
But sometimes the call will be dropped to Earth via a ground station
that is thousands of kilometres away from the call's final destination.
So when the call is finally routed through the terrestrial phone network
to get to your favourite Ukrainian arms dealer, the route it takes will
also be added to the final cost of the call.
If your nearest ground station is in Saudi Arabia, as with Iridium - and
long distance calls between Saudi and Ukraine are hefty- that will be
reflected in the cost of the call to the network. However, though these
costs will be reflected in the cost to the network, they will probably
be averaged out by the network, because trying to administer individual
call charges that reflect all these components is an administrative
nightmare.
Iridium has already ditched plans for a multi-tiered billing system in
favour of one that reflects the average cost of calls across its entire
network.
Peter Bruce and Lawrence Hawkins of Pertec, a Midrand company with
several years' experience in the supply of satellite communication
equipment, point out however that in many cases, especially in Africa,
satellite phone calls can be cheaper than using the normal network. Many
African hotels charge a standard $8 to $9 a minute for international
calls, three times the $2 to $3 a minute of Inmarsat.
The phones
Satellite phones, at the moment, will come as a shock, aesthetically.
Some of them are not much larger than the cellphones of two or three
years ago - but they have bloody great antennas that are almost the same
size. This is not a problem when you're out in the bush, but when you're
in an obscure African capital that nonetheless has a cellular network,
you're going to wish that your dual mode cellular/satellite phone was as
small as the sleek models nestled in the palms of your smug negotiating
partners.
At least one Iridium phone, made by Kyocera, has got it right - it
comprises a tiny cellular phone, which slots into a satellite phone
extension. The cellular component is extremely versatile, being
compatible not only with South Africa's GSM (global systems mobile)
cellular network standard, but also with the advance mobile phone
service, code division multiple access and personal communications
service standards.
Another Iridium phone offered by MTN, the [Motorola] 9500, has got it
badly wrong. Already cumbersome as a satphone, cellular usage demands a
cumbersome extension. Motorola are obviously embarrassed by the size of
the 9500's antenna - it is always coyly folded away in the close-up
shots.
However, by next year the ICO satellite system will be online, offering
phones costing around $1 000 and "similar in appearance, size and weight
to today's GSM phones". ICO phones will receive "high- penetration call
notification alerts", telling users inside a building that they need to
get outside to take a call.
Though the assumption is usually that a satellite phone is a kind of
global cellular phone, a variety of satphone terminals also exist,
including fixed installations, car installations and maritime
installations. Fixed installations could well be useful for companies
which need to be in constant contact with an office in another country
to which the cost of international calls is very high, and to which the
satellite rate is cheaper. A fixed satphone installation can be fitted
seamlessly into an office PABX system, allowing calls to that office by
all who need to make them.
In choosing a satellite system, there are a number of factors to take
into account, and nothing (especially data services) should be taken for
granted.
Speed
We have all made long-distance phone calls where there was a significant
delay in the signal, meaning a wait of a couple of seconds before
hearing the person at the other end of the line.The delay can be
irritating. More significantly, what is irritating for you can be a
major complication when you're trying to use data services and want your
notebook computer to talk to the Internet, as the delays can confuse
your computer and slow things down significantly.
The length of the delay (or latency, which is the time a signal takes to
get to a satellite and back) in a satellite call will depend on the
altitude of the satellite, or how far the signal has to travel from
earth and back. In the case of low Earth orbit (LEO) systems such as
Iridium and Globalstar, that distance is not too great. In the case of
Inmarsat, it's at least a third to half a second. The ICO network may
end up having something of a delay as well, though not too great. ICO
satellites will be in medium Earth orbit (MEO), at an altitude of 10
000km.
Reliability
One of the key problems in making sure a satellite call is reliable or
that your connection doesn't get dropped, is making sure the hand-over
from one satellite passing over you to the next is smooth.
The lower the satellite network, the faster they pass over you and the
more often hand- overs must be made. The principle is similar to that of
a cellular network, only the network moves past you, rather than you
through the network (as you drive, for example).
But because satellites are always a lot further away from you than your
nearest Vodacom artificial palm tree/antenna, the signals between you
and the satellite are weaker, and need a line-of-sight connection.
In other words, you or your antenna must be outside. This is not a
problem if you have a fixed satphone installation with an antenna on top
of an office building. But if you're standing beside that office
building with a portable satphone, with half the sky blocked- off, your
call-window will become half the horizon-to-horizon time of the
satellite. This would be five minutes in the case of Iridium satellites,
which take 10 minutes to cross the sky.
Globalstar is hoping to address this particular problem with something
called path diversity, which allows different satellite signals to be
received as one stronger signal. This is expected to reduce signal
interference caused by buildings or other natural features. In the case
of Iridium, there are other factors affecting reliability.
At the moment it is expected that the 66 Iridium satellites will expire
in five years, which means Iridium will need to replace them.
But according to the Internet publication Wired, Iridium doesn't have
any money - and the fact that it has no customers means getting that
money is going to be difficult.
On May 7, the company's stock plunged to $10,44, down from $65,13 a year
ago. Iridium lost $505-million in the first quarter of 1999. It is
$2-billion in debt, and at the end of March had only 8 000 customers, a
third of its own forecast figure.
To its credit, Iridium is not, as a Sunday Times article on May 23
suggested, pulling out of South Africa. But given the absence of
meaningful data services - the future of communications - it may be that
by this time next year MTN is going to be looking for a new satellite
partner.
Capacity
Data is an incredibly important component of modern satellite
communications. In 1997, only 1% to 2% of Pertec's customers wanted data
capability in their satellite service. That figure is now up to 70%, and
it's only going to get bigger.
Because of this, the Iridium network seems doomed to failure. At
present, it is not offering data services, and when it does introduce
them, it will be limited to an extraordinarily rudimentary 2 400 bytes
per second (bps). This is one-twentieth the speed of the 56K modem you
probably use for a dial- up Internet connection. Web surfing will be
impossible, and only very limited fax and e- mail services will be at
all practical. Most other satellite networks plan data services up to at
least 9 600bps, which should allow limited web usage.
If data is really your thing, there are many broadband satellite
networks dedicated to supplying it, at a cost.
Coverage
The automatic assumption with satellite communications is that there is
global coverage. Wrong.
There are two factors limiting coverage - the altitude and number of
satellites in a network, and network licensing agreements. Iridium-type
satellites use highly-focused, 20km-wide spot beams (satellite signals
allowing and excluding coverage in specific areas) that can be switched
on and off as they pass over specific countries, and they will be
switched off if Iridium does not have specific agreements with the
telecoms authorities in certain countries.
In geosynchronous Earth orbit (GEO) satellites such as Inmarsat, it is
impossible to focus the spot beams to that degree, and coverage is
almost global. Because networks are trying to maximise the number of
satellite spot beams covering particular landmasses, sections of the
ocean can be altogether neglected. So don't assume that your Iridium
phone is going keep you in touch throughout a cruise or solo yacht race.
Other services
So what if all this still sounds absolutely crazily expensive, but you
desperately need some kind of satellite communications? For around $1
000, you can get (from Pertec) a Magellan GSC-100 terminal, which runs
off the Orbcomm network. Looking like a large walkie- talkie, it
combines a simple e-mail type messaging system with a global positioning
system (GPS) capability. Useful for yachtsmen and adventurers on a
shoestring, messages cost around $0,30 and one cent per byte, or
character. And it'll never get lost in the bottom of your handbag.
Iridium also offers two services in addition to its current satphone
service that could well be extremely useful: the Iridium World Page
service, essentially a global one-way satellite paging service, and
Iridium global roaming.
Because of its agreements with international cellular networks, signing
up with Iridium global roaming is the one-stop solution to worldwide
roaming, ending the need to set up specific roaming capabilities for
each country one might be visiting.
A similar ICO Roam system is under development.Or else you can just
wait.
These are not the only satellite networks around. In about two years,
the Ellipso system should come online. It uses innovative skewed
elliptical orbits to maximise the time any particular satellite is
visible to a particular area, and anticipates charging an extremely
competitive $0,35 a minute for mobile services and $0,08 a minute for
fixed services, along with data and paging services.
In the next four years other Inmarsat-like systems such as ACeS,
Satphone, ACS, Thuraya, APMT and EAST will be coming online. Other
networks, such as Orbcomm, offer simpler messaging services. (Copyright
1999 Mail and Guardian.) Distributed via Africa News Online by Africa
News Service.
(Copyright 1999 Africa News Service)
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