Real-time experimental demonstration of a computationally efficient hybrid OFDM DFMA PON

This paper presents the first real-time experimental demonstration of a hybrid OFDM DFMA PON. The presented PON is validated for two channels (I or Q) occupying two subwavelength bands. The hybrid OFDM DFMA PON eliminates the need for a dedicated matching filter at the receiver for each individual channel, by employing a single FFT operation to recover all channels, thereby achieving lower computational complexity. The hybrid OFDM DFMA PON used in conjunction with a joint sideband processing technique, when compared to a DFMA PON under the exact same operating conditions, is shown to offer increased performance, including a lower received optical power of up to 1.2 dB for the adopted FEC limit at a given bit rate. The experimentally demonstrated PON is also proven to be significantly more tolerant to the symbol timing offset effect at the OLT receiver. Furthermore, compared to the DFMA PON’s OLT receiver, the implemented FFT-based receiver is shown to operate at a drastically reduced logic clock rate and with significantly lower DSP complexity. The hybrid OFDM DFMA PON is thus shown to have numerous advantages over the DFMA PON.