Wireless Networks

Satellite Networks for Wireless Data Applications

Wireless industry visionaries and missionaries have long used the words - anywhere, anytime, ubiquitous, and global, to describe a wireless future in which the ability to communicate electronically will not be dependent upon person's location. They have excited the imaginations of users, fully aware all the while that there are vast territories of the world where it is too difficult to install terrestrial networks and/or too costly to justify them on an economic basis. It is to the reach of satellite-based communications that these visionaries look when they extend the wireless scenario to remote areas, mountains, lakes, nations, continents, and, ultimately, the globe.

The prospect of being able to connect a home-office computer to a remote hydroelectric site, say, or to collect data from an isolated lake in Alaska, or to have a police car in northernmost parts of Canada access a law enforcement database in Ottawa — or even to have a sales executive pick up e-mail from a ski chalet in Swiss Alps — is very exciting indeed.

Satellite-based communications make all this possible. Although a proven technology that has been around since the 1960s (unlike PCS, which is fundamentally a new concept), its implementation in wireless applications has been relatively slow, despite its unique advantages. Chief among these advantages is the fact that it takes only a minimal number of satellites (as few as three in one implementation) to cover vast areas that can include anything from forests, mountains, and valleys, to lakes, seas, and deserts. One reason for the slow implementation has been the high cost of using satellites. Now that is changing: not only do existing satellites have capacity to spare (as in the case of Canada’s Telsat), but developing countries like India and China are also beginning to offer much cheaper satellite launchings.

For more complete information on data applications satellite networks, please refer to chapter 8 of the Mobile Computing Handbook or refer to other radio network books.

Current status (circa 2000)
There are a number of satellite networks that exist today and are extensively used for TV broadcast services. This use is well founded and economically justifiable. While satellite networks held great promise for the future of wireless data applications during the last decade, ill-fated Iridium network designed and implemented by Motorola on behalf of a large consortium has cast a gloom on the future of this industry. High capital cost of implementing these networks, long propagation delays, clunky and expensive modems, and most importantly very high per minute prices for satellite services have caused many to wonder whether this is a suitable network technology for mobile computing applications. 

Globalstar Satellite Network
Globalstar is yet another satellite company trying to stay afloat. It is too early to tell whether they have a long term future. Mobileinfo suggests that enterprise network planners should do a careful evaluation of all the alternatives and use satellite as a network option where terrestrial networks would not reach. Primary option should be based on terrestrial networks.