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The world in your hand

Cambridge Consultants has helped Iridium evolve from a voice based satellite communications business to one based on data services.

The number of users of gsm based mobile phones continues to grow, with the latest estimate claiming that well in excess of 4billion people now have access to the global mobile phone network.

Yet, despite that huge – and rapidly growing – number, there are still vast areas of the Earth's surface from which communications via mobile phone are impossible. If you're in the middle of the Sahara Desert, floating in the Pacific Ocean or exploring at the South Pole, don't expect to get any signal bars on your phone because terrestrial wired and wireless networks reach only 10% of the Earth's surface.

There is a large community of users who need to communicate from remote locations in the other 90%. The scientists at the South Pole; mariners and explorers are just some. But there is also growing demand from relief organisations for reliable communications from the sites of natural disasters such as earthquakes.

And it is this community which Iridium is looking to serve through its satellite communications network. But there is more to Iridium than mobile phone service from the middle of nowhere; the company also offers data communications facilities to enterprises and governments alike. And it will be no surprise to discover that the military is more than interested in a satellite network that provides access to 100% of the Earth's surface and which can be partitioned to provide secure links. In fact, the US Department of Defense (DoD) contributed 23% of Iridium's revenues in Q1 of 2010.

Dan Mercer, general manager of Iridium's operations in EMEA and Russia, said 20% of users access the Iridium network from positions at latitudes above 70°. "While it is possible to use geostationary satellites," he said, "the service gets worse the further north you go. Geostationary satellites can't cover the poles, for example."

The concept of using satellites to provide global communication is certainly not new; these devices have been relaying phone calls and tv programmes between continents for decades. But what is different about Iridium is the scale of its operation – 66 satellites in low earth orbit.

Neither is Iridium new. The idea first surfaced in the 1990s, mainly led by Motorola, as one of a number of similar schemes. Perhaps the most ambitious was the Teledesic network, backed by Microsoft and Bill Gates. Its initial plan was to launch 840 satellites into low earth orbit (LEO). This was scaled back to 288 satellites in 1997, but didn't get much farther. A similar approach was taken by the Globalstar consortium, which is still operating a 48 satellite network.

Mercer recalled the company's early days. "The problem was that Iridium was targeted at travelling business people and the business model was wrong."

That saw the company go bust in 2000, having spent $7.5billion on satellites and infrastructure. But a new look Iridium has risen from the ashes.

Mercer said: "Dan Colussy, who was president of Pan Am in the 1970s, pulled together a group of investors, which bought the assets for $25million. But it was only the assets; they didn't assume any debt."
That allowed Iridium to take a different approach. "This time, Iridium focused on vertical markets and it has been successful," Mercer continued. "It built cash reserves of more than $100m by the mid 2000s and now has a positive cash flow and is profitable."

It is this healthy financial position which has allowed Iridium to take a positive view of the future, with the launch of Iridium NEXT.

In the Iridium NEXT project, the company has contracted Thales Alenia Space (TAS) to build 81 new satellites. Of these, 66 will replace the current constellation, while six will be in orbit spares. A further nine will be available as ground spares. TAS has signed a fixed price contract to make the satellites for a total of $1.8bn. But the full cost of Iridium NEXT will be $2.9bn.

The launch programme starts in 2015 and will be completed in 2017. As the new satellites are put into their correct positions, the old satellites will be what Mercer described as 'deorbited', after which they will enter the Earth's atmosphere and burn up.

The 66 satellites will be aligned in six planes and orbit 780km above the Earth. Each satellite has a 4800nautical mile footprint, with 48 spot beams. Taking around 8min to pass overhead, the satellites can also communicate with each other, forming a mesh in the sky. This is important because, while the original Iridium network featured 12 groundstations, there are now just two. One, in Arizona, handles commercial traffic; the other, in Hawaii, is the portal to the US DoD."

Motorola's original plan was for the Iridium constellation to last until 2008. But the constellation's lifetime has been extended due to the first company's commercial difficulties and some judicious 'housekeeping'. Mercer noted: "With fewer customers on the network than planned, there were fewer charge/discharge cycles for the batteries and less satellite movements. These, combined with some software improvements, have stretched their life beyond 2014."

What is less obvious in the Iridium story is the role played by Cambridge Consultants. Richard Traherne, head of wireless and the company's commercial director, said it was, effectively, Iridium's virtual R&D team. "It allows Iridium to develop a product at a time when it is right for the business."

Cambridge Consultants has been working with Iridium since 2003. "When Motorola exited the project, Iridium looked to what it might do in the future," Traherne noted. "It approached us, amongst others, to design out older and proprietary technology and to develop a new handset as a basis for a future revenue stream.

"Iridium had ideas about where it wanted to go in the future, but needed help with building in flexibility. We then started to act as a platform provider, rather than a product provider."

Traherne noted that existing phone featured 1million lines of code. "We had to reverse engineer the whole system within fixed constraints, as well as bearing mind the spectrum and satellite restraints. At the end of the phone were mission critical users who would rely on the system."

In fact, it took Cambridge Consultants just 14 months to produce the new phone. "We replaced all the components, including some complex rf and digital chips," Traherne explained. "When the project started, there was no time or money to invest in chips, we had to create the design using a less integrated approach by drawing on a bunch of different radio technologies, working out the best way to bring them together at a given cost point while including future flexibility."

That phone, the Iridium 9555, brought a feature set much like that of a gsm device, including a speakerphone. Importantly, it was much smaller than the device it replaced.

Cambridge Consultants' latest design for Iridium is 9602 short burst data transceiver. This is roughly 70% smaller than the previous model and contains approximately half the number of parts. It also costs less to manufacture than the previous model, the Iridium 9601 transceiver.

Traherne said: "The Iridium 9602 uses two asics, which reduces the number of parts from 769 in the previous device to 384. The design represents a distillation of all our experience. Reliability is improved because we've taken out discrete components and, because it costs less to manufacture, it is opening up more market opportunities for Iridium."

Traherne said the 9602 owed a lot to Cambridge Consultants' radio heritage. "Over the last decade, we've developed a range of skills that allow us to put more functionality into cmos asics that would previously have needed bipolar technology. 'Vanilla' cmos lets us get the cost down through clever design.

"We have insight into other radio technologies and can pick out the best ways of doing things. Because we cover a range of radio technologies, we can bring in the best of them."

Apart from developing a smaller, less costly device, Cambridge Consultants delivered the 9602 a month ahead of schedule. "We got the asics right first time," Traherne pointed out.

The 9602 may help Iridium develop its short data burst business. These modems transmit 340byte at a time. "But, typically," said Mercer, "the message is only 30 to 50byte – and that costs about 1cent to transmit." That 50byte burst of compressed data can provide the location, speed and heading of a device being tracked. "We are currently handling millions of such messages a day," Mercer claimed.

Working with Iridium does, however, present challenges. "It's the opposite to standard cellphone technology," Traherne noted. "For one thing, the basestation is moving overhead at 18,000mph. So there's a lot of Doppler to be dealt with and the received signal is only 10 times greater than the heat of the Earth."

Iridium is now looking to develop its network to address what it sees as an unserved need – 128kbit/s data communications. It believes this will prove attractive to the maritime community.

"We needed a system that would work on a ship rolling at sea," Traherne said. "It would need to maintain a fix on a satellite travelling from 9° on one horizon, overhead and to 9° on the other horizon while being aware of the limited amount of software updates that can be made on the satellite."

The solution, called OpenPort, features a network of fixed antennas within a radome and software that tracks the satellite. "We had to use the satellite ten times more efficiently than before," Traherne said, "and allow it to process a higher data rate without an impact on the power utilisation."

There are also plans to begin to offer what the architects of the 1990s satellite networks intended: high speed data communications. Using the L band, data rates of up to 1Mbit/s can be supported, compared to today's single channel links at 2.4kbit/s. The Ka band may allow this to increase to 8Mbit/s. "We'll have the capacity to support 3m devices," Mercer claimed.

Iridium must be doing something right. From nothing, it has built a business with 400,000 subscribers which is growing at 20% a year. "We offer global connectivity," Mercer continued, "with near real time data. Users can track cargo within milliseconds."

And Iridium believes that its network of 250 service providers can only mean better things for the future. "Cambridge Consultants has helped us to develop products and services that have helped us to evolve from voice to a data network. Our customers won't use gsm mobiles," Mercer concluded, "because it doesn't work for their applications."

Author
Graham Pitcher

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