Multirate and multiquality transmission scheme using adaptive overlapping pulse-position modulator and power controller in optical CDMA networks

We propose the multirate and multiquality transmission scheme using adaptive overlapping pulse-position modulator (OPPM) and optical power controller in optical CDMA networks. In the proposed system, the multirate and the multiquality transmission can be achieved by accommodating users with the different value of M and the different transmitted power in the same network. The proposed scheme has the advantage that it is not required to change the code-length and weight depending on the required bit-rate of the user and the difference of the bit-rates does not have so much effect on the bit error probabilities (BEPs). Moreover, the difference of the power does not cause the change of bit-rate. We analyze the BEPs of the four multimedia service classes corresponding to the combinations of high/low-rates and high/low-qualities, and show that the proposed scheme can easily achieve distinct differentiation of the service classes with the simple system configuration.