Variable data rate CDMA experiment with non-geostationary ETS-VI satellite

A variable data rate CDMA system is tested for mobile and 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 such as fading, rain attenuation, and interference as well as to provide variable data rates on demand. A conceptual hardware system is developed, which uses 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. The use of FEC reduces the effect of multiple access interference, and enhances the bit error performance under CDMA conditions. Both the IF loop back and satellite link test performances of the prototype equipment prove it has the potential for personal and mobile satellite applications.