Performance analysis of single and multirate FFH-OCDMA networks based on psk modulation formats

In this paper, the performance of single and multirate fast frequency hopping optical code-division multiple-access (FFH-OCDMA) networks based on coherent modulation formats is addressed. The following modulation formats are assumed: binary and quadrature phase shift keying (BPSK and QPSK). For single rate networks, BPSK and QPSK are used as the modulation formats for all users. On the other hand, for multirate networks, BPSK and QPSK modulation formats are employed for low- and high-rate transmission users, respectively. For both networks, new bit error rate (BER) formalisms regarding the main deleterious source in OCDMA are derived, namely multiple-access interference. The mathematical formalism developed here accounts for any kind of users´ signal waveforms (which are accurately accounted for at the desired user´s receiver). As a result, it can be successfully used to carry out performance analysis of any OCDMA network. In this paper, it is shown that both low- and high-rate users can surprisingly achieve similar BER levels. In addition, it is demonstrated that incoherent on-off-keying-based networks are not good candidates for future single and multirate FFH-OCDMA implementations in this interference limited scenario. On the other hand, our results pave the way for BPSK- and QPSK-based networks, which are seen as potential candidates for next generation passive optical networks (NG-PON2), where higher data rates and a vast amount of users will be major network requirements.