Synchronous CDMA for optical subscriber systems using ´block interleave´

Synchronous code-division multiple access (S/CDMA) for optical subscriber systems is reported. ´Block interleave´ for signals modulated by the spread spectrum method is proposed. Block interleave supports phase synchronisation of codes. S/CDMA is an exciting possibility for passive double stars because it minimises interference among channels. A theoretical analysis and one experiment show that the most important factor in selecting code sequences is the small size of the maximum absolute value of crosscorrelation.