An OLT comprises: a memory; a processor coupled to the memory and configured to: determine each of a plurality of channels associated with an ONU, select a first channel from among the channels, and generate a first message comprising at least one field instructing enablement or disablement of the first channel; and a transmitter coupled to the processor and configured to transmit the first message to the ONU. A method implemented in an OLT, the method comprises: determining each of a plurality of channels associated with an ONU; selecting a first channel from among the channels; generating a first message comprising at least one field instructing enablement or disablement of the first channel; and transmitting the first message to the ONU.

In an optical communication abnormality-recovery system and method, when an abnormality occurs in transmission and reception of one wavelength of an optical line terminal of a PON system, an optical network unit that is performing communication at a certain wavelength switches the wavelength for performing the communication to another backup wavelength that is instructed in advance. The optical line terminal also performs switching so that the communication is performed using the same backup wavelength as in the optical network unit.

In an optical communication abnormality-recovery system and method, when an abnormality occurs in transmission and reception of one wavelength of an optical line terminal of a PON system, an optical network unit that is performing communication at a certain wavelength switches the wavelength for performing the communication to another backup wavelength that is instructed in advance. The optical line terminal also performs switching so that the communication is performed using the same backup wavelength as in the optical network unit.

An optical wavelength demultiplexer includes a wavelength demultiplexing device, a first wavelength filter and a first- and second-stage wavelength sub-filters. The wavelength demultiplexing device demultiplexes an input light into a first wavelength band including wavelengths λ.sub.1 and λ.sub.2 in the vicinity of 1310 nm and a second wavelength band including a wavelength λ.sub.3 of 1490 nm and a wavelength λ.sub.4 of 1550 nm to output. The first-stage wavelength sub-filter removes the wavelength λ.sub.2 longer than 1310 nm from the second wavelength band and transmits the wavelength λ.sub.3 of 1490 nm. The second-stage wavelength sub-filter removes the wavelength λ.sub.4 of 1550 nm and outputs the wavelength λ.sub.3 of 1490 nm, which is the remainder of the selected lights, with a sufficient wavelength spectral purity.

A method implemented by a transmitter, comprising encoding digital in-phase and quadrature-phase (IQ) data associated with a plurality of analog signals according to a first multi-level modulation format to produce a modulated IQ signal, encoding control information associated with the plurality of analog signals according to a second multi-level modulation format that is different from the first multi-level modulation format to produce a modulated control signal, aggregating the modulated IQ signal and the modulated control signal via time-division multiplexing (TDM) to produce an aggregated TDM signal, and transmitting the aggregated TDM signal over a communication channel.

A band control system, a band control apparatus and a communication apparatus which realize low-latency band allocation assuming a plurality of radio control units are proposed.

The band control system according to the present invention is a band allocation control system for optical communication which performs connection between a plurality of radio transmitting/receiving units connected to radio terminals and a plurality of radio control units corresponding to the plurality of radio transmitting/receiving units. Each of the radio control units includes a radio communication timing calculating unit configured to calculate a radio communication timing of each of the radio terminals in a connection network. The band control system includes a band allocation control unit configured to allocate an optical communication band according to the radio communication timing calculated by the radio communication timing calculating unit of each of the radio control units to each of a plurality of slave station apparatuses corresponding to the radio transmitting/receiving units, and a synchronization control unit configured to control synchronization among the plurality of radio control units.

A band control system, a band control apparatus and a communication apparatus which realize low-latency band allocation assuming a plurality of radio control units are proposed.

The band control system according to the present invention is a band allocation control system for optical communication which performs connection between a plurality of radio transmitting/receiving units connected to radio terminals and a plurality of radio control units corresponding to the plurality of radio transmitting/receiving units. Each of the radio control units includes a radio communication timing calculating unit configured to calculate a radio communication timing of each of the radio terminals in a connection network. The band control system includes a band allocation control unit configured to allocate an optical communication band according to the radio communication timing calculated by the radio communication timing calculating unit of each of the radio control units to each of a plurality of slave station apparatuses corresponding to the radio transmitting/receiving units, and a synchronization control unit configured to control synchronization among the plurality of radio control units.

Methods and apparatus for providing enhanced optical networking service and performance which are particularly advantageous in terms of low cost and use of existing infrastructure, access control techniques, and components. In the exemplary embodiment, current widespread deployment and associated low cost of Ethernet-based systems are leveraged through use of an Ethernet CSMA/CD MAC in the optical domain on a passive optical network (PON) system. Additionally, local networking services are optionally provided to the network units on the PON since each local receiver can receive signals from all other users. An improved symmetric coupler arrangement provides the foregoing functionality at low cost. The improved system architecture also allows for fiber failure protection which is readily implemented at low cost and with minimal modification.

The present invention provides a receiving device and an optical switching fabric apparatus, where the receiving device includes: multiple selecting modules, a fast optical switch connecting to each selecting module, an output module connecting to all the fast optical switches, and a receiver connecting to the output module, where the selecting module is configured to receive a multiwavelength optical signal, select and filter a first optical signal of a preset time segment in the multiwavelength optical signal; the fast optical switch is configured to select a second optical signal from the first optical signal filtered by the selecting module; the output module is configured to combine optical signals separately selected by all the fast optical switches into one optical burst signal; and the receiver is configured to perform optical-to-electrical conversion on the optical burst signal, and extract service data from an electrical signal.

The present invention provides a receiving device and an optical switching fabric apparatus, where the receiving device includes: multiple selecting modules, a fast optical switch connecting to each selecting module, an output module connecting to all the fast optical switches, and a receiver connecting to the output module, where the selecting module is configured to receive a multiwavelength optical signal, select and filter a first optical signal of a preset time segment in the multiwavelength optical signal; the fast optical switch is configured to select a second optical signal from the first optical signal filtered by the selecting module; the output module is configured to combine optical signals separately selected by all the fast optical switches into one optical burst signal; and the receiver is configured to perform optical-to-electrical conversion on the optical burst signal, and extract service data from an electrical signal.