PERFORMANCE ANALYSIS OF OPTICAL SYNCHRONOUS PPM CDMA SYSTEMS WITH INTERFERENCE CANCELER UNDER NUMBER-STATE LIGHT-FIELD/

The performance of direct-detection optical synchronous code-division multiple-access (CDMA) systems using pulse position modulation (PPM) s ignaling (PPM/CDMA) with interference canceller is analyzed. In optica l CDMA systems, it is known that the maximum number of simultaneous us ers in CDMA systems is limited by the maximum tolerable interference a mong users. If the receiver is able to estimate this interference and cancel or reduce its effect, the capacity of CDMA systems can be incre ased and the system performance can be improved. There are some ways t o increase the system performance, that is, using PPM and interference canceller. However, the system using both PPM and interference cancel ler has not been analyzed. In this paper, the upper bound on the bit e rror probability of optical synchronous PPM/CDMA systems with interfer ence canceller is derived, and the bit error probability of optical sy nchronous PPM/CDMA systems is evaluated under the assumption of number -state light field where the background noise is negligible. We compar e the bit error probability of the optical synchronous PPM/CDMA system s with interference canceller to that of the optical synchronous PPM/C DMA systems without interference canceller and to those of optical syn chronous OOK/CDMA systems with and without interference canceller. We show that optical synchronous PPM/CDMA systems with interference cance ller have better bit error probability performance.