Experimental demonstration of a statistical OFDM-PON with multiband ONUs and elastic bandwidth allocation

The statistical orthogonal frequency division multiplexing passive optical network (OFDM-PON) concept with multiband optical network units (ONUs) is experimentally tested with two users and an optical line terminal at 2.5/5 Gb/s total effective capacity with binary phase-shift keying (BPSK)/quadrature phase-shift keying (QPSK) modulation. Both downstream and uplink were measured based on intensity modulation and direct detection. The ONUs consisted oflocal nonpreselected wavelength distributed feedback laser sources centrally controlled to reduce overlapping probability. In addition, a radio-frequency mixing stage in the ONUs up/downconverts the user data to/from the OFDM signal, reducing the computational effort. Compared with ONUs processing the whole signal, the multiband approach presents comparable results with almost symmetrical power budgets of around 25 and 20 dB with BPSK and QPSK, respectively, which could increase up to 4.5 dB by allocating a spectral guard interval between the optical carrier and the OFDM data. Furthermore, elastic bandwidth allocation is explored, which is shown to compensate for up to 18 dB differential link loss.