Rate-flexible optical CDMA networks based on coherent modulation formats

In this paper, we propose, design, and assess the performance of optical coherent access networks based on optical code-division multiple-access (OCDMA) based on three distinct coherent modulation formats, namely, BPSK, QPSK, and 16-QAM. We design a flexible network architecture based on these coherent modulation formats to provide either single data rate transmissions or multiple data rate transmissions. In this way, the network supports users with the same transmission rate, or group of users transmitting at different data rates. We derive new close-form analytical expressions for both single and multiple rate use cases to assess the performance of the coherent OCDMA network. Results shown that the multi-rate data traffic from the users can coexist almost transparently in terms of network performance. The flexible OCDMA network might be a prospective alternative for implementing coherent systems for different service provision according to traffic demand requirements while supporting with high capacity, security, and simultaneous numbers of subscribers. Keywords: BPSK, QPSK, 16-QAM, coherent network, BER, OCDMA