Hybrid DFT-Spread OFDM-Digital Filter Multiple Access PONs for Converged 5G Networks

In this paper, we propose hybrid discrete Fourier transform (DFT)-spread orthogonal frequency division multiplexing (OFDM)-digital filter multiple access (DFMA) passive optical networks (PONs) for the first time to the best of our knowledge. In this case, digital filtering based on digital signal processing is applied to individual DFT-spread OFDM signals from various optical network units, and a single fast Fourier transform operation and its following data recovery processes are implemented in a pipelined approach in the optical line terminal. The proposed networks maintain all salient features associated with previously reported hybrid OFDM–DFMA PONs. More importantly, they additionally reduce the upstream signal peak-to-average power ratios by less than 2 dB. As a direct result, in comparison with the hybrid OFDM–DFMA PONs, the proposed PONs increase the upstream system power budget by more than 3 dB and reduce the minimum required digital-to-analog converter/analog-to-digital converter quantization bits by at least 1 bit.