Performance enhancement of a dynamic optical code division multiple access communication system by signal clipping

An enhancement of a dynamic optical code division multiple access (DOCDMA) communication system is proposed by clipping the signal at the output of the decoder of each receiver. In a DOCDMA system, the central wavelength of a tunable optical filter (TOF) is dynamically varied according to a functional code at the transmitter during the bit period before the transmission of the data. The system is modeled and analyzed taking into account the multiple access interference, thermal noise, and phase induced intensity noise. The performance of the system with signal clipping is compared with that of no clipping and to a spectral amplitude coding system that uses either a Hadamard code or a modified quadratic congruence code. The results show that the proposed signal clipping method improves the bit error rate performance.