Evaluation of variable data rate CDMA for multimedia personal satellite communications with ETS-VI and COMETS satellites

A variable data rate CDMA system is evaluated for personal multimedia random access satellite communications. This system utilizes a constant occupied bandwidth, and has variable data rates and processing gains to mitigate communication link impairments and interference as well as to provide variable data rates on demand. A conceptual hardware system is developed using MSK-type constant envelope direct sequence spread spectrum modulation and handles data rates from 4-64 kbps with FEC. The receiver structure provides variable data rates on demand during a call without the aid of system control earth stations. The proposed system is described, along with the CDMA performance of the prototype equipment with the non-geostationary ETS-VI satellite at the S-band (2.3/2.1 GHz) with Ka-band (30/20 GHz) feeder link. Both the IF loop back and satellite link test performance of the prototype equipment prove it has the potential for personal multimedia satellite applications. The experimental program of the next test satellite COMETS is also briefly described.