Patent ID: 7869710

Claim:
An optical network unit (ONU) in an Ethernet passive optical network (E-PON) that communicates at least upstream via a time division multiplexing (TDM) scheme, the optical network unit comprising: a medium access controller for accessing a medium without temporal overlapping in order to transmit to an optical line terminal (OLT) during one or more allocated TDM time slots without having a data collision occur with transmissions from other ONUs in upstream transmission; a burst-mode optical transceiver for converting a signal transferred from the medium access controller into an optical signal before outputting the signal in the upstream transmission; and a complex programmable logic device (CPLD) for controlling an optical output of the burst-mode optical transceiver by monitoring an optical-output control signal from the medium access controller, wherein the CPLD detects the optical-output control signal from the medium access controller at monitoring intervals and sequentially stores information regarding whether the optical-output control signal is normal or abnormal at each monitoring interval in a register, and each bit of the register indicates whether the optical-output control signal is normal or abnormal at a corresponding monitoring interval.