Delay-division-multiplexing (DDM) involves the use of signal preprocessing for the detection of data via sub-Nyquist analog-to-digital sampling, based on preallocated relative sampling delays among optical network users (ONUs) in an orthogonal frequency-division multiplexing (OFDM) passive optical network (PON). If a DDM-PON consists of M virtual groups, the sampling rate at the receivers is only 1/M of the Nyquist rate, but the maximum capacity of each ONU is fixed at 1/M of the total capacity. In this study, we developed a novel DDM scheme that uses hybrid sub-Nyquist sampling rates to accommodate heterogeneous services of different capacities in an OFDM-PON. To equalize the transmission performances using hybrid sub-Nyquist sampling rates, the modification of preprocessing was proposed, and its necessity was demonstrated. Without loss of generality, we experimentally demonstrated a 25-Gbps DDM-OFDM-PON using hybrid sampling at 1/2, 1/8, and 1/32 (or 1/8, 1/16, and 1/32) of the Nyquist rate. Compared to a DDM-PON with a fixed sub-Nyquist rate, the received signals based on hybrid sub-Nyquist sampling rates show similar sensitivities. A loss budget of 26 dB was experimentally achieved using all sub-Nyquist sampling rates after employing the modified preprocessing.
- Delay-division multiplexing
- orthogonal frequency-division multiplexing
- sub-Nyquist sampling