JP2019009722A - Intra-station apparatus and optical communication control method - Google Patents

Abstract

To improve loss budget while suppressing cost.SOLUTION: In the optical access system, a plurality of subscriber devices transmits optical signals to intra-station devices by time division multiple access. The intra-station device includes a control unit in a new subscriber device that is a newly connected subscriber device for determining a preamble length used for an upstream burst optical signal from a new subscriber device on the basis of an accommodation distance of the new subscriber device or an accommodation distance of each of the new subscriber device and the registered subscriber devices registered in the intra-station device.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an intra-station device and an optical communication control method.

  In recent years, with the rapid spread of the Internet, there has been a demand for an increase in capacity of an optical access system, and an economic improvement by sophistication that contributes to OPEX (Operating Expense) and CAPEX (Capital Expenditure). Research on PON (Passive Optical Network) is underway as a method for realizing such a system. PON means that multiple transmission lines from multiple users are concentrated on a single transmission line by an optical passive element such as an optical power splitter, so that the transmission line between the center device and the optical passive element is shared by multiple users. This is an optical access communication system that is advantageous for economic improvement.

  FIG. 11 shows the configuration of a TDMA (Time Division Multiple Access) -PON system. In the PON system, in order to achieve high economic efficiency, the upward direction from the in-house device (ONU: Optical Network Unit) installed in the user's home to the in-station device (OLT: Optical Line Terminal) installed in the communication carrier building In this communication, TDMA technology is applied, and a communication method in which the bandwidth of the uplink signal is shared by a plurality of users is adopted. For this reason, a burst optical transmitter that transmits an optical signal at a time specified by the OLT is used for the transceiver mounted on the ONU, and the optical power level transmitted from the ONU under the OLT is used for the transceiver mounted on the OLT. A burst optical receiver that can correctly receive burst optical signals having different values is used.

  Currently, in Japan, an economical optical access communication system GE-PON (Gigabit Ethernet (registered trademark) -PON) sharing a line capacity of 1 Gbps (Gigabit per second) class by time division multiplexing (TDM) with a maximum of 32 users. ) Has been introduced. As a result, FTTH (Fiber to the home) service has been provided at a realistic price for users, and has rapidly spread.

  On the other hand, 10G-class 10G-EPON is being researched as a next-generation optical access system that can meet the needs for higher capacity, and standardization was completed in IEEE in 2009. In this system, due to the increase in the bit rate of the optical transceiver, it is possible to realize a large capacity while using the same transmission line portion as that of the existing GE-PON.

K. Hara, S. Kimura, H. Nakamura, N. Yoshimoto, and H. Hadama, "Ultra Fast Response AC-coupled Burst-mode Receiver with High Sensitivity and Wide Dynamic Range for 10G-EPON Systems", OECC2010, 8A4- 2, 2010, p.434-435

  The user area that can be accommodated by the PON system, that is, the distance from the OLT to the ONU is defined by a loss budget. The loss budget is an allowable transmission loss value expressed as a difference between the transmission power of the ONU transmitter and the minimum reception sensitivity of the OLT burst optical receiver. Further, in general GE-PON and 10G-EPON, an optical fiber transmission loss of an upstream signal wavelength is larger than a downstream signal wavelength, and therefore, the loss budget is a factor that is dominant in the upstream signal transmission characteristics. Expanding these loss budgets and increasing the number of ONUs that can be accommodated by a single OLT means increasing the number of users sharing the cost, which is very important from the viewpoint of system economics. On the other hand, in order to expand these loss budgets, previous studies so far require additional devices such as optical amplifiers that compensate for optical loss, and there are operational issues such as power supply and remote maintenance management. There was a problem with the cost increase due to the addition of devices.

  In view of the above circumstances, an object of the present invention is to provide an in-station device and an optical communication control method capable of improving loss budget while suppressing cost.

  One aspect of the present invention is an in-station device in an optical access system in which a plurality of in-house devices transmit an upstream burst optical signal to an in-station device by time division multiple access, and the in-home device newly connected to the in-station device From a new home device, based on the accommodation distance of the new home device, or the accommodation distance of each registered home device that is the home device registered in the new home device and the local device, A control unit for determining a preamble length used for the upstream burst optical signal.

  One aspect of the present invention is the above-described in-station device, wherein the control unit determines that the same preamble length is used for the upstream burst optical signal from each of the new in-home device and the registered in-home device.

  One aspect of the present invention is the above-described in-station device, wherein the control unit determines a preamble length used for an upstream burst optical signal from the in-home device after establishing initial communication with the in-home device.

  One aspect of the present invention is the above-described in-station device, wherein the control unit assigns a preamble length used for an upstream burst optical signal from the in-home device according to an accommodation distance of the in-home device.

  One aspect of the present invention is the above-described intra-station apparatus, further including a determination unit that determines the accommodation distance based on reception power of an upstream burst optical signal received from the in-house apparatus.

  One aspect of the present invention is an optical communication control method executed by the in-station device in an optical access system in which a plurality of in-home devices transmit an upstream burst optical signal to the in-station device by time division multiple access. Based on the accommodation distance of the new in-house device, or the accommodation distance of each of the registered in-home devices registered in the new in-house device and the in-station device. And a preamble length determining step for determining a preamble length used for an upstream burst optical signal from the new in-home device.

  According to the present invention, it is possible to improve the loss budget while suppressing the cost.

FIG. 3 is a diagram illustrating an uplink burst frame configuration according to an embodiment of the present invention. It is a figure for demonstrating the preamble frame length allocation method by 1st Embodiment. It is a flowchart which shows the preamble frame length allocation process to ONU in OLT by the embodiment. It is a figure for demonstrating the preamble frame length allocation method by 2nd Embodiment. It is a flowchart which shows the preamble frame length allocation process to ONU in OLT by the embodiment. It is a figure for demonstrating the preamble frame length allocation method by 3rd Embodiment. It is a flowchart which shows the preamble frame length allocation process to ONU in OLT by the embodiment. It is a block diagram which shows the structure of OLT by 4th Embodiment. It is a block diagram which shows the structure of OLT by 5th Embodiment. It is a block diagram which shows the structure of ONU by 6th Embodiment. 1 shows a configuration of a conventional TDMA-PON system. It is a figure which shows the flame | frame structure of the upstream burst signal of a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Embodiments described herein relate generally to an intra-station apparatus of an optical access system using TDMA technology applied to TDM-PON and the like.

  FIG. 12 is a diagram showing a frame configuration of an upstream burst signal in the conventional PON system. This figure shows the frame structure of an upstream burst frame used in a PON system represented by GE-PON and 10G-EPON and applying the TDMA technology to upstream signal transmission. The uplink burst frame shown in the figure is mainly composed of a preamble, a payload, and an end-of-burst frame from the top. The preamble is a frame necessary for synchronization so that the OLT burst optical receiver can correctly receive the data in the burst frame. The payload is a frame in which data to be transmitted is inserted. The end-of-burst is a frame that serves as a mark of the end of the burst signal.

  In TDMA-PON systems represented by conventional GE-PON systems and 10GE-PON systems, the payload portion of these upstream burst frames is serviced as a variable frame according to the transmission request bandwidth of the ONU. On the other hand, a fixed frame length is assigned to other frames such as a preamble. For example, in the standardized specification of the 10G-EPON system, an arbitrary fixed value from 800 ns to 1312 ns is defined.

  On the other hand, considering the loss budget expansion in upstream signal transmission, that is, the improvement in the reception sensitivity characteristics of the burst optical receiver used for OLT, the longer the preamble length of the upstream burst frame, the more relaxed the request for the time constant of the receiving circuit. Improvement of the minimum receiving sensitivity characteristic of dB can be expected. In other words, by extending the length of the preamble frame of the upstream burst frame, it is possible to expect an improvement in loss budget without major modification to the existing system or the like.

  Therefore, in this embodiment, by optimizing the length of the preamble frame in the upstream burst frame, a loss budget expansion effect is realized without adding a device to the existing PON system, and further, the efficiency of upstream signal band utilization efficiency is improved. Plan.

  FIG. 1 is a diagram illustrating an upstream burst frame configuration according to the present embodiment. The difference between the burst frame configuration shown in the figure and the conventional burst frame configuration shown in FIG. 12 is that the preamble has a variable length. In this way, with the frame configuration in which the preamble frame length is variable, the loss budget can be expanded by improving the minimum receiving sensitivity of the OLT. As described above, the upstream burst frame of the PON system to which the TDMA technology is applied for upstream signal transmission is mainly composed of a preamble, a payload, and an end-of-burst frame from the beginning. The upstream burst frame configuration according to the present embodiment is basically based on the configuration following these.

  In the PON system, when registering an ONU for the first time, the OLT grasps the ONU accommodation distance using, for example, a ranging function and holds it as ONU information. The accommodation distance is a distance between the ONU and the OLT that accommodates the ONU. In this embodiment, the preamble frame length allocated to the ONU is determined using the ONU accommodation distance information indicated by the ONU information held by the OLT. Also, the OLT instructs each ONU by setting information on the preamble frame length determined for the ONU in a control signal instructing the light emission time (upstream burst signal allocation band) of the laser mounted on the ONU.

  By making these preamble lengths variable, for example, in an optical access system that accommodates an ONU located at a short distance from the OLT, it is possible to shorten the preamble length and improve the bandwidth utilization efficiency of upstream signals. On the other hand, in an optical access system that accommodates an ONU located at a long distance from the OLT, when the preamble length of the upstream burst frame is set to a standardized length, the OLT cannot receive the upstream burst signal burst. In this case, the preamble frame length is further expanded from the standard specification. As a result, ONUs located at a long distance can be accommodated by the OLT. Detailed embodiments will be described below.

[First Embodiment]
FIG. 2 is a diagram for explaining a preamble frame length allocation method according to the present embodiment. The optical access system 1 shown in the figure is, for example, a TDMA-PON system. The optical access system 1 includes an OLT 2 and a plurality of ONUs 3. The optical transmission lines connected to the OLT 2 are branched by N (N is an integer of 2 or more) optical transmission lines by the optical power splitter 4, and these N optical transmission lines are respectively connected to the optical power splitters 5-1 to 5-1. The branch is further branched into a plurality of optical transmission lines by 5-N and connected to the ONU 3. In the figure, the optical power splitter 5-n (n is 1 or more N an integer) _{M n} stand connected to the optical transmission path branched by _{(M n} is an integer of 1 or more) of ONU3 respectively, ONU3- n-1 to 3-n- _Mn . In addition, ONU3-n-1 to 3-n- _Mn are collectively referred to as ONU3-n when not specified either. In FIG, _{ONU3-1-1~3-1-M 1} is a short distance from OLT2, _{ONU3-2-1~3-2-M 2} is medium range from OLT2, ONU3-N-1~3- N- _MN is located at a long distance from OLT2.

The optical access system 1 of the present embodiment realizes loss budget expansion by improving the minimum reception sensitivity of the OLT 2 by making the preamble frame length of the upstream burst optical signal variable. Therefore, the OLT 2 sets the preamble frame length that can be accommodated by the farthest ONU 3-N to all the ONUs 3-1-1 to 3- It is applied to N- _MN and operated.

  FIG. 3 is a flowchart showing a preamble frame length allocation process to the ONU 3 by the OLT 2 of the present embodiment. In the present embodiment, the ONU 3 connected to the OLT 2 is always assigned a preamble frame length corresponding to the ONU 3 located at the longest distance among the ONUs 3 registered in the OLT 2.

  When the OLT 2 registers the newly connected ONU 3 for the first time, the OLT 2 receives a new registration request from the ONU 3 (step S110). For example, the OLT 2 broadcasts a signal (for example, Discovery GATE) for discovering an unregistered ONU 3, and the newly connected unregistered ONU 3 transmits a new registration request as a response to the signal. As a result, the OLT 2 newly registers the ONU 3 that has transmitted the new registration request in its own apparatus, and allocates a transmission band and the like.

  After establishing the initial communication with the OLT 3 as described above, the OLT 2 uses the ranging function to grasp the accommodation distance of the newly registered ONU 3 and holds it as ONU information. In the ranging function, the OLT 2 estimates the distance to the ONU 3 based on the time taken from the time when the distance measurement signal transmission request is transmitted to the ONU 3 until the time when the distance measurement signal returned from the ONU 3 is received. To do. In this embodiment, the OLT 2 determines the preamble length to be assigned with reference to the distance information of the ONU 3 accommodated at the farthest distance. Therefore, a table in which the preamble length to be assigned according to the accommodation distance is set is prepared in advance and stored in the OLT 2.

  The OLT 2 refers to the stored ONU information, and determines whether or not the accommodation distance of the newly registered ONU 3 is the farthest compared to the accommodation distances of all the ONUs 3 already registered in the OLT 2. (Step S120). When the OLT 2 determines that there is an ONU 3 farther than the accommodation distance of the newly registered ONU 3 among all the ONUs 3 that have already been registered in the OLT 2 (step S120: NO), the currently used preamble frame length is set. It assigns also to the newly registered ONU (step S130).

  On the other hand, when the OLT 2 determines that the accommodation distance of the newly registered ONU 3 is farther than the accommodation distance of all the ONUs 3 already registered in the OLT 2 (step S120: YES), the accommodation distance of the newly registered ONU 3 Is read from the table and assigned to all ONUs 3 (step S140).

  The OLT 2 gives information on the assigned preamble frame length to the control signal that indicates the light emission time (upstream burst signal allocation band) of the laser mounted on the ONU 3 and instructs each ONU 3.

  In the present embodiment, an excessive preamble frame length is assigned to the ONU 3 at a short distance, so that the utilization efficiency of the uplink signal band is lowered. On the other hand, since the timing at which the preamble frame length allocation sequence is required is only when the ONU 3 is newly connected, there is an advantage that the processing in the OLT 2 is lightened.

[Second Embodiment]
FIG. 4 is a diagram for explaining the preamble frame length allocation method of the present embodiment. An optical access system 1a shown in the figure is, for example, a TDMA-PON system, and realizes loss budget expansion by improving the minimum reception sensitivity of OLT by making the preamble frame length of the upstream burst optical signal variable. The optical access system 1a shown in the figure has a configuration in which the OLT 2 in the optical access system 1 according to the first embodiment shown in FIG. 2 is replaced with an OLT 2a.

In the preamble frame length allocation method shown in the figure, the OLT 2a collectively sets the preamble length corresponding to the ONU 3 accommodation distance division (for example, short distance, medium distance, long distance) to the ONU 3 of the corresponding accommodation division. assign. For example, OLT2a the distance between OLT2a within the _{ONU3-1-1~3-1-M 1} included in the short-range segment, assigning a preamble frame length corresponding to the short distance. Further, OLT2a is the _{ONU3-2-1~3-2-M 2} in which the distance is included in the section of the medium distance and OLT2a, assign a preamble frame length corresponding to the medium distance, the distance between OLT2a far of the ONU3-N-1~3-N- M N contained in the segment, it assigns a preamble frame length corresponding to the long distance.

  FIG. 5 is a flowchart showing a preamble frame length allocation process to the ONU 3 by the OLT 2a of the present embodiment. In the present embodiment, a table in which the correspondence between the accommodation distance section and the assigned preamble frame length is prepared in advance and stored in the OLT 2a. The OLT 2a refers to the table and assigns a preamble frame length corresponding to the accommodation distance section of the ONU 3 to each connected ONU 3.

  When the OLT 2a registers a newly connected ONU 3 for the first time, the OLT 2a receives a new registration request from the ONU 3 (step S210). Similar to the OLT 2 of the first embodiment, the OLT 2a newly registers the ONU 3 that has transmitted the new registration request, and assigns the transmission band and the like. Then, the ranging function is used to determine the accommodation distance of the newly registered ONU 3. To grasp. The OLT 2a determines which accommodation distance category for determining the preamble frame length the grasped accommodation distance corresponds to (step S220).

  The OLT 2a refers to the stored table and assigns the preamble frame length corresponding to the determined accommodation distance section to the newly registered ONU 3. That is, when the OLT 2a determines that the accommodation distance section is a long distance (step S220: long distance), the OLT 2a reads the preamble frame length corresponding to the long distance from the table and assigns it to the newly registered ONU 3 (step S230). Further, when the OLT 2a determines that the accommodation distance section is a medium distance (step S220: medium distance), the OLT 2a reads the preamble frame length corresponding to the medium distance from the table and assigns it to the newly registered ONU 3 (step S240). If the OLT 2a determines that the accommodation distance section is a short distance (step S220: short distance), the OLT 2a reads the preamble frame length corresponding to the short distance from the table and assigns it to the newly registered ONU 3 (step S250).

  In this way, the OLT 2a determines the preamble frame length of each ONU 3. The OLT 2a gives information about the assigned preamble frame length to the control signal that indicates the light emission time (upstream burst signal allocation band) of the laser mounted on the ONU 3, and instructs each ONU 3.

  In this embodiment, since the preamble frame length is assigned according to the accommodation distance section of the ONU 3, the processing in the OLT 2a becomes heavy compared to the first embodiment. On the other hand, since the preamble frame length is optimized by the accommodation distance section, there is an advantage that the band use efficiency in the uplink signal is improved as compared with the first embodiment. In FIGS. 4 and 5, as an example, the accommodation distance section of the ONU 3 is shown as three sections of long distance, medium distance, and short distance, but the accommodation distance section may be further subdivided. According to this embodiment, for example, the ONU 3 having a shorter accommodation distance section than the certain accommodation distance section has a preamble frame length shorter than the preamble frame length of the uplink burst frame configuration of the prior art, and a longer accommodation distance section than a certain accommodation distance section. The ONU 3 can be assigned a preamble frame length longer than the preamble frame length of the conventional uplink burst frame configuration.

[Third embodiment]
FIG. 6 is a diagram for explaining the preamble frame length allocation method of the present embodiment. An optical access system 1b shown in the figure is, for example, a TDMA-PON system, and realizes loss budget expansion by improving the minimum reception sensitivity of OLT by changing the preamble frame length of the upstream burst optical signal. The optical access system 1b shown in the figure has a configuration in which the OLT 2 in the optical access system 1 according to the first embodiment shown in FIG. 2 is replaced with an OLT 2b. In the present embodiment, the OLT 2b assigns an optimum preamble frame length to the ONU 3 having a different distance from the OLT 2b according to the distance.

  FIG. 7 is a flowchart showing a preamble frame length allocation process to the ONU 3 by the OLT 2b of the present embodiment. In this embodiment, a table in which the correspondence between the accommodation distance and the assigned preamble frame length is prepared in advance and stored in the OLT 2b. The OLT 2b refers to the table and assigns a preamble frame length corresponding to the accommodation distance of the ONU 3 to each connected ONU 3.

  When the OLT 2b registers the newly connected ONU 3 for the first time, the OLT 2b receives a new registration request from the ONU 3 (step S310). Similar to the OLT 2 of the first embodiment, the OLT 2b newly registers the ONU 3 that has transmitted the new registration request, and assigns the transmission band and the like. Then, the ranging function is used to determine the accommodation distance of the newly registered ONU 3. To grasp. The OLT 2b refers to the stored table and reads the preamble frame length corresponding to the accommodation distance of the newly registered ONU 3 (step S320). The OLT 2b assigns the read preamble frame length to the newly registered ONU 3 (step S330).

  In this way, the OLT 2b determines the preamble frame length of each ONU 3. The OLT 2b gives information about the assigned preamble frame length to the control signal that indicates the light emission time (upstream burst signal allocation band) of the laser mounted on the ONU 3, and instructs each ONU 3.

  According to the present embodiment, for example, an ONU 3 having an accommodation distance shorter than a certain accommodation distance has a preamble frame length shorter than the preamble frame length of the prior art uplink burst frame configuration, and an ONU 3 having an accommodation distance longer than a certain accommodation distance is used. A preamble frame length longer than the preamble frame length of the conventional uplink burst frame configuration can be allocated.

  In this embodiment, since the preamble frame length is optimized according to the accommodation distance of the ONU 3, the processing in the OLT 2b becomes heavy compared to the first embodiment and the second embodiment. On the other hand, since the preamble frame length is optimized for each ONU 3 based on the accommodation distance, there is an advantage that the band use efficiency in the uplink signal is improved as compared with the first embodiment and the second embodiment.

  In both the second and third embodiments, the preamble frame length assigned to each ONU by the OLT is determined using a table, and the allocation granularity set in the table is different. However, it can be realized with essentially the same device configuration.

[Fourth Embodiment]
In this embodiment, a configuration example of the OLT will be described.
FIG. 8 is a block diagram showing a configuration of the OLT 200 of the present embodiment. The OLT 200 is used in an optical access system that realizes loss budget expansion by improving the minimum reception sensitivity of the OLT by changing the preamble frame length. The OLT 200 is configured to be able to implement a preamble length optimization method using ONU accommodation distance information. The OLT 2 according to the first embodiment, the OLT 2a according to the second embodiment, and the OLT 2b according to the third embodiment. Can be used.

  The OLT 200 shown in FIG. 8 includes a control unit 210, an ONU information holding unit 220, an allocation table holding unit 230, and an OLT optical transmission / reception unit 240. The control unit 210 performs bandwidth control and preamble frame length allocation processing according to the first to third embodiments. When the OLT 200 is used as the OLT 2 of the first embodiment, the control unit 210 performs the preamble frame length allocation process shown in FIG. 3, and when the OLT 200 is used as the OLT 2a of the second embodiment, the preamble frame length allocation shown in FIG. When the process is used as the OLT 2b of the third embodiment, the preamble frame length allocation process shown in FIG. 7 is executed.

  The ONU information holding unit 220 holds ONU information in which information about each ONU 3 is set. The ONU information includes information on the accommodation distance of the ONU 3. The allocation table holding unit 230 holds a table that is referred to in order to determine the preamble length in the preamble frame length allocation processing of the first to third embodiments. When the OLT 200 is used as the OLT 2 of the first embodiment or the OLT 2b of the third embodiment, the allocation table holding unit 230 sets a table in which the correspondence between the accommodation distance and the allocated preamble frame length is set as the second table. When used as the OLT 2a of the embodiment, a table in which the correspondence between the accommodation distance section and the assigned preamble length is held.

  The OLT optical transceiver 240 includes an optical transmitter driver 241, an optical transmitter 242, an optical multiplexer / demultiplexer 243, an optical receiver 244, a current / voltage converter 245, and an equalizing amplifier 246. The optical transmission unit driver 241 drives the optical transmission unit 242. The optical transmission unit 242 converts the downlink signal from an electrical signal to an optical signal and outputs the optical signal to the optical multiplexing / demultiplexing unit 243. The optical multiplexing / demultiplexing unit 243 multiplexes / demultiplexes the downstream optical signal and the upstream optical signal. The optical multiplexing / demultiplexing unit 243 transmits the downstream optical signal output from the optical transmission unit 242 to the ONU 3 through the optical transmission path. The optical multiplexing / demultiplexing unit 243 outputs the optical signal received from the ONU 3 via the optical transmission path to the optical receiving unit 244. The optical receiver 244 receives the upstream optical signal and converts it into an electrical signal. The current / voltage conversion unit 245 converts the current photoelectrically converted by the light receiving unit 244 into a voltage and amplifies it. The equalization amplification unit 246 equalizes and amplifies the voltage converted by the current / voltage conversion unit 245 and outputs the voltage to the control unit 210.

  When registering the ONU 3 for the first time, the control unit 210 of the OLT 200 grasps the accommodation distance of the ONU 3 using the ranging function and holds it in the ONU information holding unit 220. The control unit 210 determines a preamble frame length to be applied to the ONU 3. The control unit 210 sets the preamble length control information indicating the determined preamble frame length in the control signal that indicates the light emission time (upstream burst signal allocation band) of the laser mounted on the ONU 3 and instructs each ONU 3 .

  In the configuration of the OLT 200 shown in FIG. 8, the control unit 210 operates according to the allocation sequence shown in FIG. 3, FIG. 5, or FIG. 7, and the ONU 3 accommodation distance information held in the ONU information holding unit 220 and the allocation table holding The preamble frame length assigned to each ONU 3 connected to the OL 200 is determined with reference to the table held in the unit 230.

[Fifth Embodiment]
In this embodiment, another configuration example of the OLT will be described. The OLT of this embodiment is used in an optical access system that realizes loss budget expansion by improving the minimum reception sensitivity of the OLT by making the preamble frame length variable as in the above-described embodiment. The OLT according to the present embodiment is configured to enable a preamble length optimization method using ONU accommodation distance information. The OLT 2 according to the first embodiment, the OLT 2a according to the second embodiment, and the third implementation. It can be used as a form of OLT 2b. However, the OLT according to the present embodiment performs a process of estimating the accommodation distance by referring to the reception power of the upstream burst optical signal received from the ONU, instead of the process of grasping the accommodation distance of the ONU by the ranging function. This is a configuration in which the preamble length allocated to is optimized according to the reception power of the upstream burst optical signal.

  FIG. 9 is a block diagram showing the configuration of the OLT 200a of the present embodiment. In this figure, the same parts as those of the OLT 200 according to the fourth embodiment shown in FIG. The OLT 200a shown in the figure includes a control unit 210a, an ONU information holding unit 220, an allocation table holding unit 230, and an OLT optical transmission / reception unit 240a. The OLT optical transceiver 240a includes an optical transmitter driver 241, an optical transmitter 242, an optical multiplexer / demultiplexer 243, an optical receiver 244, a current / voltage converter 245, an equalization amplifier 246, and a determination unit 247. .

  The determination unit 247 estimates the accommodation distance of the ONU 3 that is the transmission source of the upstream burst optical signal, based on the reception power of the upstream burst optical signal received by the OLT optical transmission / reception unit 240a. The determination unit 247 estimates the ONU3 accommodation distance by determining the current component of the subsequent stage of the optical reception unit 244 determined by the determination unit 247, the voltage component of the subsequent stage of the current / voltage conversion unit 245, and the circuit state of the current / voltage conversion unit 245. And based on one or more of the circuit states in the equalization amplification unit 246. The circuit state is represented by an amplification factor parameter, for example. The control unit 210a acquires information about the accommodation distance of the ONU 3 from the determination unit 247. Other operations of the control unit 210a are the same as the operations of the control unit 210 of the fourth embodiment.

  In the configuration of the OLT 200a shown in FIG. 9, the determination unit 247 acquires a current level / voltage level and an amplification factor parameter in each electric circuit as information indicating the reception power of the upstream burst optical signal received by the optical reception unit 244. And the accommodation distance of ONU3 is determined based on the acquired information. The control unit 210a operates according to the allocation sequence shown in FIG. 3, FIG. 5, or FIG. 7 using the information on the accommodation distance determined by the determination unit 247, and stores the ONU 3 accommodation distance information held in the ONU information holding unit 220. The preamble frame length to be allocated to the ONU 3 connected to the OL 210a is determined with reference to the table held in the allocation table holding unit 230. The control unit 210a sets the preamble length control information indicating the determined preamble frame length in the control signal that indicates the light emission time (upstream burst signal allocation band) of the laser mounted on the ONU 3, and instructs each ONU 3. .

[Sixth Embodiment]
In this embodiment, a configuration example of the ONU will be described.
FIG. 10 is a block diagram showing the configuration of the ONU 300 of this embodiment. The ONU 300 corresponds to uplink signal preamble length optimization by OLT. The ONU 300 shown in the figure can be used as the ONU 3 in the first to third embodiments. The ONU 300 includes an optical signal transmission / reception unit 310 and a frame processing unit 320. The frame processing unit 320 includes a downlink reception frame processing unit 321, an uplink preamble length control signal monitoring unit 322, an uplink preamble length setting unit 323, and an uplink transmission frame generation unit 324.

  The optical signal transmission / reception unit 310 receives a downstream optical signal from the OLT. The optical signal transmission / reception unit 310 converts the received downstream optical signal into an electrical signal and inputs the electrical signal to the downstream reception frame processing unit 321. The downlink reception frame processing unit 321 performs processing for separating various control signals stored in the header of the frame and downlink signal data. Here, the uplink preamble length control signal monitoring unit 322 monitors the control signal related to the preamble length setting of the uplink signal stored in the header of the frame, and reads the preamble length control information assigned to the uplink signal frame transmitted by the ONU 300. The control signal related to the preamble length setting is, for example, a control signal in which burst control information is set. The burst control information is information stored in the header of the frame, and is included in a control signal indicating the light emission time (upstream burst signal allocation band) of the laser mounted on the ONU. The uplink preamble length control signal monitoring unit 322 takes over the read uplink preamble length control information to the uplink preamble length setting unit 323.

  The uplink preamble length setting unit 323 determines the preamble length assigned to the uplink signal frame based on the uplink preamble length control information read by the uplink preamble length control signal monitoring unit 322. The uplink signal preamble length information determined by the uplink preamble length setting unit 323 is taken over by the uplink transmission frame generation unit 324.

  The uplink transmission frame generation unit 324 generates an uplink signal frame having a preamble length based on the preamble length information of the uplink signal determined by the uplink preamble length setting unit 323. Based on the generated upstream signal frame and burst control information, the optical signal transmission / reception unit 310 transmits the upstream burst optical signal to the OLT via an optical transmission unit (not shown) included in the optical signal transmission / reception unit 310.

  According to the embodiment described above, the in-station device of the optical access system that applies the time division multiple access technology and transmits the temporally intermittent optical signal to the in-station device includes the control unit. For example, the optical access systems are the optical access systems 1, 1 a, 1 b, the in-station devices are OLT 2, 2 a, 2 b, 200, 200 a, and the in-home devices are ONUs 3, 300. The control unit of the in-station device registers the new home device that is newly connected to the in-station device, the accommodation distance of the new in-home device, or the registration of the new in-home device and the in-house device registered in the in-station device. The preamble length used for the upstream burst optical signal from the new in-home device is determined based on the accommodation distance of each of the in-home devices.

  For example, the control unit may determine that the same preamble length is used for the upstream burst optical signal from each of the new home device and the registered home device.

Further, the control unit may determine a preamble length used for an upstream burst optical signal from the in-home device after the initial communication is established between the in-station device and the in-home device.
The control unit may assign the preamble length used for the upstream burst optical signal from the in-home device individually or for each accommodation distance section according to the accommodation distance of the in-home device.
The intra-station device may further include a determination unit that determines the accommodation distance based on the reception power of the upstream burst optical signal received from the in-home device.

  According to the embodiment described above, it is possible to expand and improve the loss budget while suppressing costs.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  The present invention can be applied to an in-station device of an optical access system to which TDMA technology is applied.

1, 1a, 1b ... optical access _{system, 2,2a, 2b, 200,200a ... OLT} , 3-1-1~3-N-M N, 300 ... ONU, 4,5-1~5-N ... optical Power splitter, 210, 210a ... control unit, 220 ... ONU information holding unit, 230 ... allocation table holding unit, 240, 240a ... OLT optical transmission / reception unit, 241 ... optical transmission unit driving unit, 242 ... optical transmission unit, 243 ... optical coupling Demultiplexing unit, 244 ... Optical receiving unit, 245 ... Current / voltage conversion unit, 246 ... Equalization amplification unit, 247 ... Determination unit, 310 ... Optical signal transmission / reception unit, 320 ... Frame processing unit, 321 ... Downstream received frame processing unit , 322 ... Uplink preamble length control signal monitoring unit, 323 ... Uplink preamble length setting unit, 324 ... Uplink transmission frame generation unit

Claims (6)

The in-station device in an optical access system in which a plurality of in-house devices transmit an upstream burst optical signal to the in-station device by time division multiple access,
A new home device that is a home device that is newly connected to the in-station device, an accommodation distance of the new home device, or a registered home device that is the home device registered in the new home device and the in-station device, respectively. A control unit for determining a preamble length to be used for an upstream burst optical signal from the new in-home device based on the accommodation distance of
An intra-station device comprising: The control unit determines that the same preamble length is used for an upstream burst optical signal from each of the new home device and the registered home device,
The in-station device according to claim 1. The control unit determines a preamble length to be used for an upstream burst optical signal from the home device after establishing initial communication with the home device.
The in-station device according to claim 1. The control unit assigns a preamble length to be used for an upstream burst optical signal from the in-home device according to an accommodation distance of the in-home device,
The in-station device according to claim 3. A determination unit that determines the accommodation distance based on reception power of an upstream burst optical signal received from the in-home device;
The intra-station device according to any one of claims 1 to 4. An optical communication control method executed by the in-station device in an optical access system in which a plurality of in-home devices transmit an upstream burst optical signal to the in-station device by time division multiple access,
A new home device that is a home device that is newly connected to the in-station device, an accommodation distance of the new home device, or a registered home device that is the home device registered in the new home device and the in-station device, respectively. A preamble length determination step for determining a preamble length used for an upstream burst optical signal from the new in-home device based on the accommodation distance of
An optical communication control method.

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