Experimental demonstrations of 30Gb/s/λ digital orthogonal filtering-multiplexed multiple channel transmissions over IMDD PON systems utilizing 10G-class optical devices

Abstract

By utilizing digital orthogonal filtering (DOF) in the digital domain, we report, for the first time, experimental demonstrations of aggregated 30.078Gb/s/λ transmissions of DOF-multiplexed spectrally-overlapped and/or frequency gapless six channels over IMDD PON systems incorporating off-the-shelf and low-cost 10G-class optical devices. Experimental results show that simple adaptive channel power loading implemented in the digital domain enables very similar transmission performances of individual channels regardless of their locations in the digital filter space. As a direct result of the interplay between the transmission system-associated negative chromatic dispersion and the intensity modulation-induced frequency chirp, negative power penalties of >0.2dB are experimentally observed for all the involved channels under various transmission system configurations. In addition, excellent performance robustness of the demonstrated systems is also obtainable for various transmission distances up to 45km.

Hybrid SSB OFDM-Digital Filter Multiple Access PONs

“…To address the aforementioned technical challenges, a digital filter multiple access (DFMA) PON has been proposed [4], which utilizes SDN-controllable digital orthogonal filters to dynamically and independently multiplex and demultiplex multiple channels of arbitrary bandwidth granularity without requiring expensive analogue optical/electrical components. Extensive theoretical investigations and experimental demonstrations of the DFMA PON have been conducted in the cost-effective IMDD application scenarios [4]- [6]. However, the number of required digital filtering process implemented in the optical line terminal (OLT)-embedded digital signal processing (DSP) function is proportional to optical network unit (ONU) count, therefore a large number of ONUs simultaneously accommodated by the PON can unavoidably result in relatively high OLT DSP complexity and operational expenditure.…”

Concurrent Inter-ONU Communications for Next Generation Mobile Fronthauls based on IMDD Hybrid SSB OFDM-DFMA PONs

“…As discussed in Section II, the ONU and OLT receivers employ similar signal demodulation DSP procedures. In the this experiments, the signal demodulation procedures include signal re-sampling [29], frame synchronization, serial-to-parallel (S/P) conversion, cyclic prefix deletion, 128-point FFT operation, sideband identification, sideband data processing, conventional OFDM subcarrier equalization and data decoding. In the sideband identification process, the subcarriers in each channel are identified and the ONUs and OLT can easily select their desired channels for signal demodulation.…”

Experimental Demonstrations of Hybrid OFDM-Digital Filter Multiple Access PONs

“…Subsequently, a digital sampling oscilloscope (DSO) digitizes the received electrical signal at a sampling speed of 25GS/s@8-bit and finally performs off-line signal demodulation process by a Matlab program. The signal demodulation procedure includes signal resampling [8], frame synchronization, serial-to-parallel (S/P) conversion, cyclic prefix (CP) removal, single 128 (32×4) point FFT operation, signal sideband identification, sideband data processing, conventional OFDM subcarrier equalization and QAM decoding. To identify an OFDM signal, the 64 subcarriers in the positive frequency bin are evenly classified into two subcarrier groups.…”

“…To address the aforementioned technical challenges, digital filter multiple access (DFMA) PONs have been proposed [6]- [8], where multiple gapless channels of arbitrary bandwidth granularity can be dynamically and independently multiplexed/de-multiplexed by transceiver-embedded SDN-controllable digital orthogonal filters without employing additional optical/electrical hardware. However, the digital signal processing (DSP) complexity of the corresponding optical line terminal (OLT) grows proportionally with optical network unit (ONU) count [9], as such for a DFMA PON accommodating a large number of ONUs, the significantly high OLT DSP complexity may become a bottleneck challenge limiting DFMA PON's practical implementation.…”