2.2　Symbols

Symbol　English Name

3R　Re-amplification，Reshaping，Retiming

AIS　Alarm Indication Signal

ALS　Automatic Laser Shutdown

APD　Avalanche Photo Diode

APR　Automatic Power Reduction

BA　Amplifier

CBR　Constant Bit Rate

CWDM　Coarse Wavelength Division Multiplexing

DPSK　Differential Phase Shift Keying

DP-QPSK　Dual Polarization Quadrature Phase Shift Keying

DQPSK　Differential Quadrature Phase Shift Keying

DWDM　Dense Wavelength Division Multiplexing

EM　Element Management

ES　Errored Second

FEC　Forward Error Correction

LCT　Local Craft Terminal

LOF　Loss of Frame

LOP　Loss of Pointer

LOM　Loss of Multi-frame

LOS　Loss of Signal

MPI-R　Main Path Interface at the Receiver

MPI-S　Main Path Interface at the Sender

NRZ　Non-return to Zero

OADM　Optical Add-drop Multiplexer

OCP　Optical Channel Protection

ODB-PSBT　Optical Duobinary PSBT

ODCa　ODUk Clock of type"a"

ODU　Optical De-multiplexer Unit

ODUk　Optical Channel Data Unit-k

OLA　Optical Line Amplifier

OMSP　Optical Multiplex Section Protection

OMU　Optical Multiplexer Unit

OOF　Out of Frame

OSA　Optical Spectrum Analyser

OSC　Optical Supervisory Channel

OSNR　Optical Signal to Noise Ratio

OTM　Optical Terminal Multiplexer

OTN　Optical Transport Network

OTU　Optical Transponder Unit

PA　Pre-amplifier

P-DPSK　Partial Differential Phase Shift Keying

PIN　Positive Intrinsic-Negative

PMD　Polarization Mode Dispersion

PM-DQPSK　Polarization Multiplexing-DQPSK

PM-QPSK　Polarization Multiplexing-QPSK

PSBT　Phase Shaped Binary Transmission

RZ　Return to Zero

RZ-DQPSK　Return to Zero-DQPSK

ROADM　Reconfigurable Optical Add-drop Multiplexer

SDH　Synchronous Digital Hierarchy

STM　Synchronous Transport Module

T-MUX　Transport Multiplexer

WDM　Wavelength Division Multiplexing