Abstract
Spectrally Efficient CDMA (SE-CDMA) is a multiple access and modulation scheme proposed for multi-beam geostationary communications satellites that provides fixed service directly to the end users. The SE-CDMA is designed to meet the service requirements for high spectral efficiency and low bit e1TOr rate (BER) given the on-board power limitations. Its implementation consist of a concatenated Reed-Solomon/Turbo channel encoder, of a two step spreading operation isolating the satellite beams and users within each beam and of a M-ary PSK modulator. The up and down SE-CDMA links are considered to be coupled at the satellite by a CDMA routing circuit which performs a de-spreading and re-spreading operation.This paper presents the system architecture and the BER performance of the proposed SE-CDMA. Performance results show that the system can provide high spectral efficiency at very low BER and at low Eb/No.