Abstract: A modified polyolefin resin having an intended adhesion strength to various substrates even when graft modification may be carried out by using an ?,?-unsaturated carboxylic acid derivative having a cyclic structure. The modified polyolefin resin may be a modified product of a polyolefin resin and satisfies conditions (A) to (C): condition (A)—a modifying component includes an ?,?-unsaturated carboxylic acid derivative having a cyclic structure; condition (B)—a ring-opening degree expressed by formula (1) is 40 or more; and condition (C)—the polyolefin resin includes an ethylene structural unit, ring-opening degree=modification degree K×ring-opening rate R??(1) wherein, in the formula (1), the modification degree K is a grafting weight (wt. %) of the ?,?-unsaturated carboxylic acid derivative, and the ring-opening rate R is a ring-opening rate (%) of the cyclic structure in the ?,?-unsaturated carboxylic acid derivative.

Abstract: An amplifier applied to TIA is provided to suppress the noise caused by a current source. An amplifier constituting a transimpedance amplifier includes an inductor element inserted between a current source connected to an input terminal of an amplification stage and a power source voltage line. The current source includes a first transistor in which a base terminal is connected to a current control bias and a collector terminal is connected to the input terminal. The inductor element is inserted between the emitter terminal of the first transistor and the power source voltage line.

Abstract: An amplifier applied to TIA is provided to suppress the noise caused by a current source. An amplifier constituting a transimpedance amplifier includes an inductor element inserted between a current source connected to an input terminal of an amplification stage and a power source voltage line. The current source includes a first transistor in which a base terminal is connected to a current control bias and a collector terminal is connected to the input terminal. The inductor element is inserted between the emitter terminal of the first transistor and the power source voltage line.

Abstract: An OLT configures combinations of wavelength pairs used for upstream and downstream signals, in a wavelength multiplexing optical communication system which performs single-core bidirectional transmission of a plurality of upstream and downstream signals, in such a way that the maximum value of the chromatic dispersion delay amount calculated from each wavelength pair is less than the maximum value of the chromatic dispersion delay amounts calculated when the combinations of wavelength pairs used for upstream and downstream signals are both allocated from the short wave side.

Abstract: In a case where a wavelength to be assigned to a subscriber-side device, to which a downstream wavelength has been assigned, is to be changed from the currently used (Source) downstream wavelength to a different changeover target (Target) downstream wavelength, a downstream wavelength changeover instruction message that indicates the change target wavelength is generated. In a case where a wavelength to be assigned to the subscriber-side device, to which an upstream wavelength has been assigned, is to be changed from the currently used (Source) upstream wavelength to a different changeover target (Target) upstream wavelength, an upstream wavelength changeover instruction message that indicates the change target wavelength is generated. The downstream wavelength changeover instruction message and the upstream wavelength changeover instruction message are respectively independently generated, and only the wavelength for which the wavelength changeover instruction message was generated is changed.

Abstract: An OLT configures combinations of wavelength pairs used for upstream and downstream signals, in a wavelength multiplexing optical communication system which performs single-core bidirectional transmission of a plurality of upstream and downstream signals, in such a way that the maximum value of the chromatic dispersion delay amount calculated from each wavelength pair is less than the maximum value of the chromatic dispersion delay amounts calculated when the combinations of wavelength pairs used for upstream and downstream signals are both allocated from the short wave side.

Abstract: An optical communication system of the present invention switches a communication wavelength from a current communication wavelength to a auxiliary communication wavelength when an abnormality occurs in a communication wavelength between a station-side device and any one of a plurality of subscriber devices. Further, this optical communication system switches a communication wavelength used for communication between the subscriber device and the station-side device that perform communication using the auxiliary communication wavelength from the auxiliary communication wavelength back to the current communication wavelength when communication is recovered from an abnormality in the current communication wavelength.

Abstract: In a case where a wavelength to be assigned to a subscriber-side device, to which a downstream wavelength has been assigned, is to be changed from the currently used (Source) downstream wavelength to a different changeover target (Target) downstream wavelength, a downstream wavelength changeover instruction message that indicates the change target wavelength is generated. In a case where a wavelength to be assigned to the subscriber-side device, to which an upstream wavelength has been assigned, is to be changed from the currently used (Source) upstream wavelength to a different changeover target (Target) upstream wavelength, an upstream wavelength changeover instruction message that indicates the change target wavelength is generated. The downstream wavelength changeover instruction message and the upstream wavelength changeover instruction message are respectively independently generated, and only the wavelength for which the wavelength changeover instruction message was generated is changed.

Abstract: A transmission start time correction method of a WDM/TDM-PON system includes: a completion instruction procedure in which a station-side subscriber accommodation apparatus issues an instruction using a downstream signal for instructing a subscriber apparatus to perform wavelength switching, the downstream signal including a transmission start time of an upstream signal indicating completion of the wavelength switching of the subscriber apparatus, the upstream signal being transmitted by the subscriber apparatus after the wavelength switching; an instruction completion transmission procedure in which the subscriber apparatus transmits the upstream signal indicating the completion of the wavelength switching at a wavelength after switching at the instructed transmission start time after the wavelength switching is completed in accordance with the instruction; and a transmission start time correction procedure in which the station-side subscriber accommodation apparatus measures a reception time of the upstream

Abstract: A wavelength and bandwidth allocation method which includes in order a wavelength determination step S4 of determining a plurality of wavelengths of an uplink signal from each ONU to OLT to guarantee a guaranteed bandwidth corresponding to a subscription service class of each ONU and a reference bandwidth distribution step S5 of distributing, as reference bandwidths, all bandwidths of the plurality of wavelengths determined in the wavelength determination step S4 to each ONU according to the subscription service class of each ONU and making the reference bandwidths of ONUs whose subscription service classes are the same be the same.

Abstract: 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.

Abstract: A protection method wherein an ONU switches a reception wavelength to a backup wavelength so as to be logically connected to a backup OSU designated in advance for each ONU when the ONU detects a failure in an OSU to which the ONU is originally assigned, while the ONU keeps on holding its own connection information with the OLT. In the OLT, a backup OSU for the ONU which is originally assigned to the failed OSU is notified of the information on the ONU when the OLT detects a failure in an OSU. In this way, the ONUs which are originally assigned to the failed OSU resumes communication in a short period.

Abstract: An optical communication system of the present invention switches a communication wavelength from a current communication wavelength to a auxiliary communication wavelength when an abnormality occurs in a communication wavelength between a station-side device and any one of a plurality of subscriber devices. Further, this optical communication system switches a communication wavelength used for communication between the subscriber device and the station-side device that perform communication using the auxiliary communication wavelength from the auxiliary communication wavelength back to the current communication wavelength when communication is recovered from an abnormality in the current communication wavelength.

Abstract: A transmission start time correction method of a WDM/TDM-PON system includes: a completion instruction procedure in which a station-side subscriber accommodation apparatus issues an instruction using a downstream signal for instructing a subscriber apparatus to perform wavelength switching, the downstream signal including a transmission start time of an upstream signal indicating completion of the wavelength switching of the subscriber apparatus, the upstream signal being transmitted by the subscriber apparatus after the wavelength switching; an instruction completion transmission procedure in which the subscriber apparatus transmits the upstream signal indicating the completion of the wavelength switching at a wavelength after switching at the instructed transmission start time after the wavelength switching is completed in accordance with the instruction; and a transmission start time correction procedure in which the station-side subscriber accommodation apparatus measures a reception time of the upstream

Abstract: A discovery method, an optical communication method, and an optical communication system which can reduce an error of RTTs when an identifier is fixed after an allocated wavelength has been changed in wavelength-tunable WDM/TDM-PON and can prevent lowering of the bandwidth utilization efficiency. A table, in which a correspondence between child nodes and fixed identifiers as well as the RTTs of a frame with each of the identifiers in all combinations of allocated wavelengths are recorded, is created through a discovery process.

Abstract: 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.

Abstract: A protection method wherein an ONU switches a reception wavelength to a backup wavelength so as to be logically connected to a backup OSU designated in advance for each ONU when the ONU detects a failure in an OSU to which the ONU is originally assigned, while the ONU keeps on holding its own connection information with the OLT. In the OLT, a backup OSU for the ONU which is originally assigned to the failed OSU is notified of the information on the ONU when the OLT detects a failure in an OSU. In this way, the ONUs which are originally assigned to the failed OSU resumes communication in a short period.

Abstract: A wavelength and bandwidth allocation method which includes in order: a wavelength allocation step of allocating each wavelength of an uplink signal to each ONU so that the sum of target bandwidths each allocated as a target to each of the ONUs to which each wavelength of the uplink signal is allocated does not exceed a bandwidth allocated to each wavelength of the uplink signal; and a bandwidth allocation step of allocating a bandwidth to each of the ONUs based on any one of a plurality of requested bandwidths accepted from each of the ONUs in each wavelength of the uplink signal so that the bandwidth actually allocated to each of the ONUs converges to the target bandwidth allocated as a target to each of the ONUs.

Abstract: An OLT controller makes each optical transceiver transmit a search signal at a prescribed time so that the search signals reach all ONU connection ends of an optical transmission path. In the case where an ONU connected to the ONU connection end of the optical transmission path is unregistered, when the ONU controller receives the search signal, the ONU controller tunes a wavelength of an optical transmitter of the ONU to a wavelength corresponding to the search signal and makes the optical transmitter transmit a response signal to an OLT.

Abstract: A discovery method, an optical communication method, and an optical communication system which can reduce an error of RTTs when an identifier is fixed after an allocated wavelength has been changed in wavelength-tunable WDM/TDM-PON and can prevent lowering of the bandwidth utilization efficiency. A table, in which a correspondence between child nodes and fixed identifiers as well as the RTTs of a frame with each of the identifiers in all combinations of allocated wavelengths are recorded, is created through a discovery process.