DSP-Based Evolution From Conventional TDM-PON to TDM-OFDM-PON

Recently, digital signal processing (DSP) methods have been extensively studied and various DSP-based schemes have been proposed for next-generation passive optical network (PON). In this paper, we combine the time-division-multiplexing (TDM) architecture with advanced DSP methods to achieve high spectrum-efficiency colorless transmission. Orthogonal frequency division multiplexing (OFDM), as the original form of various DSP methods with frequency-domain equalization (FDE), is chosen for both upstream and downstream transmissions. In the TDM-PON based on OFDM (TDM-OFDM-PON) architecture, OFDM symbols are transmitted in different time slots instead of on-off-key (OOK) bits in conventional TDM-PON. This architecture can be extended for single-carrier with FDE easily. Due to the same TDMA scheme, it can achieve maximum compatibility with current TDM-PON. A DSP-based evolution scheme from conventional TDM-PON to TDM-OFDM-PON is proposed and experimentally demonstrated by upgrading the optical line terminal (OLT) to support both OOK and OFDM signals, which can maintain the current optical distribution network (ODN) and minimize the impact for the existing service and equipment.