African skies
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 techical 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.
More information about mobile telecommunications can be found at PCReview Online at www.mg.co.za/pc/cell