yssey , Aries , Inmarsat and Ellipsat. (check table for details ) Each company is using a proprietary network of satellites, launching methods, and implementation strategies. Iridium is the company that according to industry sources will make it to market first. IridiumIn 1989 Motorola announced a proposal to launch a series of 77 satellites in low earth orbit starting in 1994. Iridium Inc. was formed to manage the programme. It aimed to offer world-wide mobile phone services. On the commercial front, Iridium plans to sign up as many operators as it can world-wide. Service would be marketed through existing cellular suppliers , networks of distributors and dealers. It even has plans to lease capacity to one of its arch rivals, Inmarsat (consists of a consortium of 65 nations ). This proposal might be intended to deflect criticism of a single US company being granted a world-wide monopoly of a part of the radio spectrum. The target users would be those breed of managers who spend many days of the month circling the globe .The cost of an Iridium handset ( Fig 3) would be $2500 and a $3 per minute tariff would be charged. Furthermore, the design of the handsets is very simple . It uses a stripped-down version of time division multiple access, TDMA, as used in the GSM cellular standard. Clearly, the use of GSM standards will be of great benefit to European and Middle East markets, as the same handsets could be used to access both terrestrial and satellite GSM cellular networks. When a user makes a call with such a dual-mode handset, it will first check for a local terrestrial signal. If it is unable to find one, then it switches to Iridium mode. In 1992 a frequency spectrum between 1610 and 1626.5 MHz was allocated for the use by LEO satellites . Iridium would utilise a 10.5 MHz part of that spectrum . Motorola gained access to this part by purchasing the bankrupt Geostar Inc. earlier that year. This company exclusively owned the licenc...
