Q1.6 What are the limitations of satellite communication systems?
Satellite communication networks require enormous start-up costs and gestation lasting several years. A careful techno-economic study is therefore essential before taking up such a venture.
There can be loss of service to vast areas if a satellite were to fail or malfunction. Fortunately, the reliability of launchers and satellite has improved. Many satellites continue to provide good service far beyond their design lifetime. The problem of in-orbit catastrophic failure is solved by deploying an in-orbit spare or by a fall-back arrangement with another operator.
Geostationary satellite systems exhibit a larger transmission delay than terrestrial system due to greater propagation path. The problem is exacerbated when the delay is accompanied by echo caused by a mismatch between terrestrial and satellite system interface. It is under these circumstances that telephone users suffer the worst annoyance. A great deal of advance has been made in echo suppressors/cancellers technology reducing the echo problem to a minimum. In particular, the delay associated with two satellite hops becomes excessive.
Low and medium Earth orbits are used to reduce delay and down-time in case of a satellite’s catastrophic failure.
End user costs for consumer/business applications are higher than those of terrestrial systems, although cost per bit continues to reduce with modern high throughput satellites.