Title :
Nonlinear effect of direct-sequence CDMA in optical transmission
Author :
Huang, Wci ; Nakagawa, Masao
Author_Institution :
Dept. of Electr. Eng., Keio Univ., Yokohama, Japan
Abstract :
The intermodulation distortion (IMD) due to laser diode (LD) nonlinearity of an asynchronous direct-sequence code division multiple access (DS/CDMA) system in optical transmission is analyzed. A third-order polynomial without memory is used to present LD nonlinearity. In DS/CDMA systems, only one harmonic of the third-order intermodulation term falls on the signal frequency band and influences the system performance. The average distortion is derived with only the information of auto-correlation functions. The results are useful for CDMA system design and performance analysis. With LD nonlinearity it is necessary to select an optimal modulation index that provides a maximum carrier-to-noise ratio (CIN). The effect of the LD nonlinearity on CDMA and frequency-division multiple access (FDMA) is also compared. The analytical method is applicable to other general nonlinearities in CDMA systems
Keywords :
code division multiple access; frequency division multiple access; intermodulation distortion; optical fibre networks; optical links; polynomials; asynchronous direct-sequence code division multiple access; autocorrelation functions; average distortion; design; direct-sequence CDMA; frequency-division multiple access; intermodulation distortion; laser diode nonlinearity; maximum carrier-to-noise ratio; optical transmission; optimal modulation index; system performance; third-order polynomial; Autocorrelation; Diode lasers; Frequency; Intermodulation distortion; Multiaccess communication; Nonlinear optics; Optical distortion; Polynomials; System analysis and design; System performance;
Conference_Titel :
Spread Spectrum Techniques and Applications, 1994. IEEE ISSSTA '94., IEEE Third International Symposium on
Conference_Location :
Oulu
Print_ISBN :
0-7803-1750-5
DOI :
10.1109/ISSSTA.1994.379517
