Dispersion effects in millimeter-wave fiber-radio systems employing direct-sequence code division multiple access

We investigate the impact of fiber chromatic dispersion on the performance of an externally modulated millimeter-wave fiber-radio system incorporating a broadband radio direct-sequence code division multiple access (DS-CDMA) scheme. In particular, we investigate the effect of dispersion on DS-CDMA signals with regard to CDMA code rate, center frequency, and modulator chirp. We show that the spreading of the signal spectrum using DS-CDMA can result in significant reductions in data amplitude variations normally experienced in externally modulated millimeter-wave fiber-radio systems. We also demonstrate the successful transmission of a 10-Mb/s data channel over a 39-GHz fiber-radio link employing DS-CDMA and consisting of 25 km of standard optical fiber and a 1-m radio link. (C) 1999 Academic Press.