Integration of variable-rate OWC with OFDM-PON for hybrid optical access based on adaptive envelope modulation

• BER performance of an integrated variable-rate OWC and OFDM-PON system is analyzed.
• Both the outdoor and indoor wireless communications are considered in the integrated system.
• Generalized BER expressions of the CE-OFDM signal with M-PAM overlay and the overlaid M-PAM signal are derived.
• The BER performance trade-off between the M-PAM overlaid CE-OFDM signal and the overlaid M-PAM signal is optimized.
• Variable-rate OWC wireless access is achieved.

In this paper, we investigate an integrated optical wireless communication (OWC) and orthogonal frequency division multiplexing based passive optical network (OFDM-PON) system for hybrid wired and wireless optical access, based on an adaptive envelope modulation technique. Both the outdoor and indoor wireless communications are considered in the integrated system. The data for wired access is carried by a conventional OFDM signal, while the data for wireless access is carried by an M-ary pulse amplitude modulation (M-PAM) signal which is modulated onto the envelope of a phase-modulated OFDM signal. By adaptively modulating the wireless M-PAM signal onto the envelope of the wired phase-modulated constant envelope OFDM (CE-OFDM) signal, hybrid wired and wireless optical access can be seamlessly integrated and variable-rate optical wireless transmission can also be achieved. Analytical bit-error-rate (BER) expressions are derived for both the CE-OFDM signal with M-PAM overlay and the overlaid unipolar M-PAM signal, which are verified by Monte Carlo simulations. The BER performances of wired access, indoor OWC wireless access and outdoor OWC wireless access are evaluated. Moreover, variable-rate indoor and outdoor optical wireless access based on the adaptive envelope modulation technique is also discussed.