Patent ID: 8705952
Filing Date: 2014-04-22
Classification: H04J

Abstract:
1. An optical wavelength division multiplex (WDM) transmission system, especially a WDM passive optical network, comprising: a central node having (i) a first WDM port and (ii) a second WDM port and a remote node having (i) a first WDM port, (ii) a second WDM port, and (iii) a plurality of channel ports, the central node first WDM port being connected to the remote node first WDM port via a bidirectional single-fiber optical working path, and the central node second WDM port being connected to the remote node second WDM port via a single-fiber bidirectional optical protection path; a group of basic optical node units (ONU's), each of which is connected to a respective remote node channel port via a bidirectional optical ONU path, each ONU comprising an optical receiver for receiving a basic downstream optical channel signal and an optical tunable transmitter for creating a basic upstream channel signal, each of the basic upstream channel signals, during a working mode of the tunable optical transmitters, being created at a basic upstream channel working wavelength and each of the basic upstream channel signals, during a protection mode of the tunable optical transmitters, being created at a basic upstream channel protection wavelength, all basic upstream channel working wavelengths and all basic upstream channel protection wavelengths lying within a basic upstream wavelength band, each ONU comprising a band multiplexer for separating and combining the basic upstream and downstream signals, each band multiplexer comprising a WDM output port connected to the bidirectional ONU path; the central node comprising (i) a group of basic tunable optical transmitters, (ii) a group of basic optical receivers, and (iii) a basic cyclic multiplexer and band separator/combiner device defining the bandwidth and spectral position of basic downstream and upstream channels: a protection control unit for detecting a failure within the working path or within the working path and the protection path and for switching the central node tunable optical transmitters and the ONU tunable optical transmitters from the present working or protection mode to the respective other mode; wherein the basic cyclic multiplexer and band separator/combiner device comprises a first cyclic channel multiplexer having a given number of channel ports and a first and a second cyclic WDM port, the channel ports being connected to the group of basic optical tunable transmitters, the first cyclic channel multiplexer being adapted to multiplex the basic downstream channel signals, if created at the downstream channel working wavelengths, into the basic downstream WDM working signal and to output the basic downstream WDM working signal at a first cyclic WDM port, and to multiplex the basic downstream channel signals, if created at the basic downstream channel protection wavelengths, into the basic downstream WDM protection signal, and to output the basic downstream WDM protection signal at the second cyclic WDM port, and wherein the basic cyclic multiplexer and band separator/combiner device comprises a second cyclic channel multiplexer having a given number of channel ports and a first and a second cyclic WDM port, the channel ports being connected to the group of basic optical receivers and the first and second cyclic WDM port receiving the basic upstream WDM working signal and the basic upstream WDM protection signal, respectively.