Abstract: A novel frequency-time spreading code by designating the different frequencies to the different mark positions of the modified prime code is proposed.Theoretical analysis demonstrates that the number of the proposed codes can amount fo p³.Cross-correlation and the sidelobe of auto-correlation of the proposed code have relatively lower values.The numerical results show that the asynchronous OCDMA system assuming the proposed code reveal excellent performance in the presence of double hard limiters.

Key words: OCDMA, frequency hopping code, modified prime code, double hard limiters