Abstract
We propose a wavelength-division-multiplexed (WDM) passive optical network (PON) to provide conventional unicast data and downstream multicast function. At the optical line terminal (OLT), for each WDM channel, a dual-drive Mach-Zehnder modulator (DDMZM) is used to generate a sub-carrier double-sideband differential-phase-shift-keying (DPSK) signal. All the central carriers are separated and subsequently modulated to deliver the multicast data, while the remaining sub-carrier DPSK signals carry the downstream unicast traffic. In the optical network units (ONUs), part of the downstream unicast signal power is re-modulated for upstream transmission, which enables source-free ONUs. The proposed scheme is experimentally demonstrated with 1.25-Gb/s downstream unicast, multicast and upstream data.
Highlights
The wavelength-division-multiplexed (WDM) passive optical network (PON) has been recognized as an attractive solution to provide broadband access for the next-generation networks
We propose a wavelength-division-multiplexed (WDM) passive optical network (PON) to provide conventional unicast data and downstream multicast function
In the optical network units (ONUs), part of the downstream unicast signal power is re-modulated for upstream transmission, which enables source-free ONUs
Summary
The wavelength-division-multiplexed (WDM) passive optical network (PON) has been recognized as an attractive solution to provide broadband access for the next-generation networks. At the ONU side, the received unicasting subcarrier DPSK signal is re-modulated as the upstream carrier before sent back to the OLT [5], which eliminates the need of laser sources or colored components in the ONUs. At the ONU side, the received unicasting subcarrier DPSK signal is re-modulated as the upstream carrier before sent back to the OLT [5], which eliminates the need of laser sources or colored components in the ONUs This proposed scheme shows several attractive features: (1) it provides a flexible multicast overlay over the conventional unicast service in WDM-PON; (2) no high-frequency electrical components are needed in the ONUs; (3) the multicast function supports fast and dynamical reconfiguration with centralized control in the OLT; (4) the downstream multicast and unicast data transmissions differ in both frequency and modulation format, which reduces the inference between them
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