Why does Globalstar need so many gateways for their network when the Iridium network relies on only two providing planetary coverage. It is the type of technology Globalstar uses which requires numerous gateways. Globalstar calls this “bend pipe” technology.
Globalstar has a 48 satellite constellation which provides global regional coverage to over 120 countries. The bend pipe technology allows the call to be beamed up from a Globalstar phone to one of the satellites where it is retransmitted to a relatively close gateway. The call is then sent one of two ways. If calling a landline or cellular phone the call is taken by the gateway and switched to the public phone network where is it sent to the call destination. If the satellite phone user is calling another Globalstar phone in the same coverage area of the gateway receiving the call, the call is relayed back to a satellite then sent down to the receiving satellite phone.
The Globalstar gateways carry out all the processing and switching of the calls rather than the satellite.
The advantage of Globalstar’s bent pipe technology is it provides great call clarity with little or no echo and time delay. A call is routed through as many as four satellites which then combines the signal into a single static free call. The quality is equal to a cellular phone in good range. The call clarity is superior to the Iridium network where the call may be carried a great distance compared to Globalstar calls.
The disadvantage of Globalstar’s bent pipe technology is that the gateways can only provide regional global coverage. With Globalstar’s 24 gateways and 48 satellites in their network they are unable to provide the planetary coverage provided by the Iridium network. If your requirement only is regional the lower cost of Globalstar’s equipment and service may meet your communication requirements.
Globalstar gateways providing service to the United States, Canada, Caribbean, and Mexico include: Cabo Rojo; Puerto Rico; San Martin, Mexico; Clifton, Texas; Smiths Falls, Ontario; High River, Alberta and Sebring, Florida.
The Iridium network uses only 2 gateways with their 66 satellite constellation. The two Iridium gateways are located in Tempe, Arizona and Wahiawa, Hawaii.
The Iridium satellite network communicate with each other using Ka-band intersatellite links. Each satellite has four intersatellite links. Unlike the Globalstar network where the satellites cannot communicate directly with each other the Iridium intersatellite links allows calls to be routed among the Iridium satellites before being transferred to a gateway or another Iridium satellite phone. These intersatellite links make Iridium impervious to natural disasters including hurricanes or earthquakes which can damage a ground station.
The Globalstar and Iridium networks have both their advantages and disadvantages. Ask your dealer which is the best solution for you.