Working Principle and Signal Flow of ETMXS Transponder

Signal Flow

The client side of the ETMXS unit can access the following types of optical signals:

• OTU1 optical signals
• Standard STM-16 optical signals
• Standard OC-48 optical signals

In the signal flow of the ETMXS unit, the transmit and the receive directions are defined. The transmit direction is defined as the direction from the client side of the ETMXS to the WDM side of the ETMXS, and the receive direction is defined as the reverse direction.

• Transmit direction

  The client-side optical module receives four channels of optical signals from client equipment through the RX1-RX4 interfaces, and performs O/E conversion.

  After O/E conversion, the four channels of electrical signals are sent to the cross-connect and service processing module. The module performs processes such as cross-connection, multiplexing, clock generating and frame processing. Then, the module outputs one channel of OTU2 signals.

  The OTU2 signals are sent to the WDM-side optical module. After performing E/O conversion, the module sends out the G.694.1-compliant 10.71 Gbit/s OTN optical signals at DWDM standard wavelengths. The OTN optical signals are output through the OUT optical interface.

• Receive direction

  The WDM-side optical module receives the G.694.1-compliant 10.71 Gbit/s OTN optical signals at DWDM standard wavelengths from the WDM side through the IN optical interface. Then, the module performs O/E conversion.

  After O/E conversion, the OTU2 signals are sent to the cross-connect and service processing module. The module performs processes such as decapsulation, clock recovery, demultiplexing and cross-connection. Then, the module outputs four channels of OTU1/STM-16/OC-48 signals.

  The client-side optical module performs E/O conversion of the four channels of electrical signals, and then outputs four channels of client-side optical signals through the TX1-X4 optical interfaces.

Module Function

• Client-side optical module

  The module consists of two parts: the client-side receiver and the client-side transmitter.

  • Client-side receiver: Performs O/E conversion of four channels of standard STM-16, OC-48, or OTU1 optical signals.
  • Client-side transmitter: Performs E/O conversion from four channels of internal electrical signals to standard STM-16, OC-48, or OTU1 optical signals.
  • Reports the working state of the client-side laser.

  When the E2ETMXS/E3ETMXS unit accesses OTU1 signals on the client side, the FEC function is not supported. Hence, the FEC function should be disabled at the receive end of the equipment that is connected to the client side of the ETMXS unit. When the E8ETMXS unit accesses OTU1 signals on the client side. the FEC funtion could be setting.

• WDM-side optical module

  The module consists of two parts: the WDM-side receiver and the WDM-side transmitter.

  • WDM-side receiver: Performs O/E conversion of standard OTN optical signals at 10.71 Gbit/s, and extracts clock from the electrical signals.
  • WDM-side transmitter: Performs E/O conversion from the internal electrical signals to standard OTN optical signals at 10.71 Gbit/s, and multiplexes the clock signals with the electrical services signals.
  • Reports the performance of the WDM-side optical interface.
  • Reports the working state of the WDM-side laser.
• Service en/de-capsulation and processing module

  The module consists of the OTN en/de-capsulation module, the SDH/SONET en/de-capsulation module, and service processing module. The service encapsulation module realizes the en/de-capsulation of signals.

  • OTN en/de-capsulation module: Processes the G.709 overheads of OTN signals, and reports the performance monitoring state of service signals.
  • SDH/SONET en/de-capsulation module: Realizes the mapping of SDH/SONET signals, and reports the performance monitoring state of service signals.
  • Service processing module: Achieves the multiplexing from OTU1 to OTU2 and the demultiplexing from OTU2 to OTU1, and performs processes such as encapsulation/decapsulation of FEC, encoding/decoding and scrambling/descrambling.
• Control and communication module
  • Controls the operations on the board.
  • Controls the operations on each module of the unit according to CPU instructions.
  • Collects the information of alarms, performance events, working states and voltage detection of each functional module of the unit.
  • Communicates with the SCC board.
  • Provides the synchronization clock signals for each module.
• Power supply module

  Converts the -48 V/-60 V DC power into the power required by each module of the board.