IRIDIUM--how to become a citizen of the world?
A revolutionary new idea
Iridium is a global wireless telecommunications system based on a network of satellites
which facilitates communication using mobile phones or pagers anywhere on Earth.
EuroTel Praha is preparing to expand the services it provides for its clients to include
something new. EuroTel Praha has already closed a roaming contract with Iridium and is
working on closer cooperation. As of fall of this year, you may participate in the
worldwide Iridium system network and consequently utilize your mobile phone without any
geographical limitations.
From anywhere with anyone
| The Iridium satellite system is designed
primarily for those who are constantly on the move and who must always be available due to
the nature of their job. Especially on intercontinental trips, differing mobile radio link
standards and insufficient coverage in many out-lying regions of the world have previously
prevented continuous communication. As of fall 1998, the Iridium system will offer a
solution for worldwide communication in three possible ways. |
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First, it is a worldwide cellular roaming service. A EuroTel cellular telephone network
user (in the case of the Czech Republic) will be able to buy/lease a portable Iridium
telephone ready for communication in one or more of the norms (Dual, Triple, or Multi Mode
models) of the participating cellular networks. From that moment on, the customer will be
able to call and be called in all world locations covered by a cellular signal, anywhere
in all the usual digital mobile radio communications networks as are GSM (primarily in
Europe), AMPS (USA), and PDC (Japan). That means that from that moment on the customer is
not subject to any limitations with his common telephone number and SIM card. The
participant receives a bill from his participating telephone company.
The second way is represented by satellite telephone communication and SIM mobile radio
communications cards from Iridium. In this case, Iridium clients around the world are
available under one number with a +8816 dialing code and receive one single telephone bill
from Iridium. With this service, the customer can call and be called in all corners of the
world. Motorola and Kyocera have been offering a satellite telephone since mid 1998.
The third option is a combination of the two previous. The participant utilizes both the
satellite link and worldwide roaming in all common cellular mobile radio communications
networks as well. If the cellular network lacks signal coverage, the link is automatically
or manually switched to the Iridium satellite system.
How does the Iridium system operate?
A complex system of 66 Iridium satellites is currently orbiting 780 kilometers above the
Earth’s surface and provides worldwide signal coverage for satellite calling. This low
orbit facilitates simple mobile phone signal receipt and transmission without undue time
delays which are characteristic for communication via geostationary satellites hanging
36,000 kilometers above the Earth. Each Iridium system satellite works independently and
orbits the planet at a speed of nearly 29,000 km/h in 100 minutes and 28 seconds.
Individual satellites communicate otherwise with mobile phones (in the 1,616-1,626.5 MHz
band, L-band), among themselves (23.18-23.38 GHz, Ka-band), and also with ground stations
(19.4-19.6 GHz, Ka-band). The satellite “operation“ is controlled by several control
centers which monitor the movement and joint communication of the satellites. The central
control center in Landsdown, Virginia, USA, monitors all 66 satellites. In order to
monitor the satellites, the main base utilizes the support of monitoring stations in
northern Canada, in Hawaii, and a mobile station in Iceland. The communication system
includes gateways which connect the satellite network with public telecommunications
networks and mobile telephone networks in all countries around the world. The transmission
of calls and data from satellites will be ensured by three of the four three-meter
diameter recording parabolic antennas aimed at the satellites. Each of the gateways is
connected to public telecommunications networks, which enables Iridium system users to
communicate with any other network participant, including of a cellular mobile phone
network. The services provided by these gateways will include the storage and control of
message flows transmitted using Iridium pagers. In terms of worldwide coverage and access
to customers, user localization and the billing of call fees is currently subsidized.
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