JP2012120136A - Optical communication system, and transmitting-and-receiving method for optical communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical communication system, and a transmitting-and-receiving method for the optical communication system, that, in PON as an efficient combination of time-division multiplexing and wavelength-division multiplexing, are capable of flexibly responding to an increase in the number of users under a station-side apparatus while suppressing an increase in cost without a change in optical power splitter between the station-side apparatus and a subscriber apparatus and a change in loss budget allocated to a transmission distance.SOLUTION: The optical communication system includes a wavelength filter 3 between a station-side apparatus 1 including plural optical transmitting-and-receiving units 11 and plural subscriber apparatuses 2. The wavelength filter 3 has a cyclic frequency for a wavelength of a downstream or upstream signal. The wavelength filter 3 includes plural station-side ports respectively connected to the plural optical transmitting-and-receiving units 11 and plural subscriber-side ports respectively connected to the plural subscriber apparatuses 2. The plural station-side ports and the plural subscriber-side ports each have the cyclic frequency for the wavelength of the downstream or upstream signal.

Description

  The present invention relates to a PON (Passive Optical Network) that effectively combines time division multiplexing and wavelength division multiplexing.

  With the rapid spread of the Internet in recent years, there has been a demand for an access service system having a large capacity, sophistication, and economy, and PON has been studied as a means for realizing it. The PON is an optical communication system that achieves economy by sharing one station-side device and a part of a transmission line with a plurality of users by using an optical multiplexer / demultiplexer using an optical passive element.

  Currently, in Japan, GE-PON (Gigabit Ethernet (registered trademark) Passive Optical Network) is mainly used as an economical optical communication system that shares a line capacity of 1 Gbps 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 fee.

  Further, in order to meet the needs of higher capacity, research on 10G-EPON having a total bandwidth of 10 Gbps class as a next-generation optical access system is underway, and international standardization was completed in 2009. This is an optical communication system that realizes an increase in capacity while increasing the bit rate of the transmitter / receiver while using the same transmission line portion as the GE-PON. In the future, it is conceivable that a large capacity exceeding 10 Gbps class, such as ultra-high definition video service and ubiquitous service, is required. However, due to an increase in cost for system upgrade, there is a problem that it is difficult to put into practical use.

  As a means for solving this, wavelength variability is added to the transmitter / receiver so that the transmitter / receiver in the station side device can be added in stages according to the bandwidth requirement, and time division multiplexing and wavelength division multiplexing ( A wavelength-tunable WDM / TDM-PON that effectively combines WDM (Wavelength Division Multiplexing) has been reported (Non-Patent Document 1). However, the demand for economic growth remains severe. A possible countermeasure is to make it possible to accommodate more users than the existing one for a station-side device. As a result, it is possible to expect economic effects such as an improvement in network utilization efficiency due to the statistical multiplexing effect and a reduction in device cost and power consumption due to relatively less station side device operation than the present.

Hirotaka Nakamura, Shinya Tamaki, Kazuki Hara, Manabu Yoshino, Shunji Kimura, Toshiya Hadama, “Wavelength Tunable WDM / TDM-PON for Flexible Service Upgrade”, 2010 IEICE Communication Society Conference, B -10B-40, September 2010. Jun-ichi Kani, Mitsuhiro Teshima, Koji Akimoto, Noboru Takachiho, Hiroo Suzuki and Katsumi Iwatsuki, "A WDM-BASED OPTICAL ACCESS NETWORK FOR WIDE-AREA GIGABIT ACCESS SERVICES", IEEE Optical Communications, pp543-548, February 2003.

  In the conventional TDM-PON, an optical power splitter is used at the branching portion. As a result, in TDM-PON, the number of branches of the optical power splitter is limited depending on the distance (operating distance) from the station side device to the subscriber device and the allowable loss budget conditions, so that it can be accommodated in the station side device. There are restrictions on users. In order to increase the number of users accommodated in the station side device in the TDM-PON in operation, it is only necessary to simply increase the number of branches of the optical power splitter, but in this case, the distribution of the loss budget allocated to the optical power splitter becomes large. It is difficult to secure an operational distance from As described above, in the TDM-PON, when the number of users that can be accommodated in the station side device is increased, the loss budget allocated to the optical power splitter and the transmission distance is changed, so that it is possible to flexibly cope with the increase in the number of users. There was a problem that could not be done.

  Because of these problems, WDM-PON is proposed which increases the light intensity under the control of the one-station side device by using a WDM filter (AWG: Arrayed Waveguide Grating, etc.) having one input and multiple output ports with low transmission loss. However (Non-Patent Document 2), it is a cost-effective system because it is necessary to install a transceiver corresponding to the wavelength to be used in each of the station side device and the subscriber device.

  Therefore, in order to solve the above-mentioned problems, the present invention provides an optical power splitter change between a station side device and a subscriber device and a transmission distance in a PON that effectively combines time division multiplexing and wavelength division multiplexing. It is an object of the present invention to flexibly cope with an increase in the number of users under a station side device while suppressing an increase in cost without changing a distributed loss budget.

  In order to achieve the above object, a wavelength filter having a recurring property for a wavelength of a downlink or uplink signal is provided between a station-side apparatus having one or a plurality of optical transceivers and a plurality of subscriber apparatuses. The wavelength filter has one or more station-side ports connected to each of the one or more optical transceivers and a plurality of subscriber-side ports connected to each of the plurality of subscriber devices. The station-side port and the plurality of subscriber-side ports have circulatory properties with respect to the wavelengths of the downstream or upstream signals.

  Specifically, the present invention has a single wavelength and a station side device having one or a plurality of optical transmitters each transmitting a downlink signal having a single wavelength among a plurality of wavelengths at one time. A plurality of subscriber devices each receiving a downlink signal, one or a plurality of station-side ports connected to each of the one or a plurality of optical transmitters, and a plurality of subscriptions connected to each of the plurality of subscriber devices An optical communication system, comprising: a subscriber-side port, and the one or more station-side ports and the plurality of subscriber-side ports each having a wavelength filter having a circulatory property with respect to a wavelength of the downlink signal. is there.

  According to this configuration, since the wavelength filter has reciprocity with respect to the wavelength of the downlink signal, the optical communication system can execute downlink communication using a small number of wavelengths. Therefore, without changing the optical power splitter between the station side device and the subscriber unit, and without changing the loss budget allocated to the transmission distance, the number of users under the station side device can be expanded while suppressing cost increase. Can be supported.

  Further, the present invention is such that each optical transmitter transmits a downlink signal having a single wavelength among a plurality of wavelengths so that each subscriber device receives a downlink signal having one wavelength at one time. It is an optical communication system characterized by controlling the timing to perform.

  According to this configuration, it is possible to provide a PON that effectively combines time division multiplexing and wavelength division multiplexing in downstream communication.

  In addition, the present invention provides a plurality of subscriber devices that each transmit an uplink signal having a single wavelength among a plurality of wavelengths at one time, and one or a plurality of subscriber devices that each receive an uplink signal having a single wavelength. A station-side device having an optical receiver, a plurality of subscriber-side ports connected to each of the plurality of subscriber devices, and one or a plurality of station-side ports connected to each of the one or more optical receivers An optical communication system, wherein the plurality of subscriber-side ports and the one or more station-side ports are provided with a wavelength filter having a circulatory property with respect to a wavelength of the uplink signal.

  According to this configuration, since the wavelength filter has a circularity with respect to the wavelength of the uplink signal, the optical communication system can execute uplink communication using a small number of wavelengths. Therefore, without changing the optical power splitter between the station side device and the subscriber unit, and without changing the loss budget allocated to the transmission distance, the number of users under the station side device can be expanded while suppressing cost increase. Can be supported.

  In addition, according to the present invention, each subscriber unit transmits an uplink signal having a single wavelength among a plurality of wavelengths so that each optical receiver receives an uplink signal having one wavelength at one time. It is an optical communication system characterized by controlling the timing to perform.

  According to this configuration, it is possible to provide a PON that effectively combines time division multiplexing and wavelength division multiplexing in upstream communication.

  According to the present invention, at least one subscriber-side port among the plurality of subscriber-side ports is connected to an optical power splitter, and the optical power splitter is connected to a plurality of the plurality of subscriber devices. This is an optical communication system.

  According to this configuration, it is possible to cope with an increase in the number of users under the station side device.

  Further, according to the present invention, each of one or a plurality of optical transmitters included in a station-side device transmits a downlink signal having a single wavelength among a plurality of wavelengths to a plurality of subscriber devices at one time. The wavelength filter has one or more station-side ports connected to each of the one or more optical transmitters and a plurality of subscriber-side ports connected to each of the plurality of subscriber devices, The one or more station-side ports and the plurality of subscriber-side ports have circularity with respect to the wavelength of the downlink signal, and each of the plurality of subscriber devices receives a plurality of wavelengths from the station-side device. The transmission / reception method of an optical communication system characterized by receiving a downlink signal having a single wavelength.

  According to this configuration, since the wavelength filter has reciprocity with respect to the wavelength of the downlink signal, the optical communication system can execute downlink communication using a small number of wavelengths. Therefore, without changing the optical power splitter between the station side device and the subscriber unit, and without changing the loss budget allocated to the transmission distance, the number of users under the station side device can be expanded while suppressing cost increase. Can be supported.

  Further, the present invention is such that each optical transmitter transmits a downlink signal having a single wavelength among a plurality of wavelengths so that each subscriber device receives a downlink signal having one wavelength at one time. It is the transmission / reception method of the optical communication system characterized by controlling the timing to perform.

  According to this configuration, it is possible to provide a PON that effectively combines time division multiplexing and wavelength division multiplexing in downstream communication.

  Further, according to the present invention, each of a plurality of subscriber devices transmits an upstream signal having a single wavelength among a plurality of wavelengths at one time to a station side device having one or a plurality of optical receivers. The wavelength filter has a plurality of subscriber-side ports connected to each of the plurality of subscriber devices and one or a plurality of station-side ports connected to each of the one or more optical receivers, The plurality of subscriber-side ports and the one or more station-side ports have circularity with respect to the wavelength of the uplink signal, and each of the one or more optical receivers is connected to the plurality of subscriber devices. A transmission / reception method for an optical communication system, wherein an uplink signal having a single wavelength among a plurality of wavelengths is received.

  According to this configuration, since the wavelength filter has a circularity with respect to the wavelength of the uplink signal, the optical communication system can execute uplink communication using a small number of wavelengths. Therefore, without changing the optical power splitter between the station side device and the subscriber unit, and without changing the loss budget allocated to the transmission distance, the number of users under the station side device can be expanded while suppressing cost increase. Can be supported.

  In addition, according to the present invention, each subscriber unit transmits an uplink signal having a single wavelength among a plurality of wavelengths so that each optical receiver receives an uplink signal having one wavelength at one time. It is the transmission / reception method of the optical communication system characterized by controlling the timing to perform.

  According to this configuration, it is possible to provide a PON that effectively combines time division multiplexing and wavelength division multiplexing in upstream communication.

  According to the present invention, at least one subscriber-side port among the plurality of subscriber-side ports is connected to an optical power splitter, and the optical power splitter is connected to a plurality of the plurality of subscriber devices. This is a transmission / reception method for an optical communication system.

  According to this configuration, it is possible to cope with an increase in the number of users under the station side device.

  The present invention is a PON that effectively combines time division multiplexing and wavelength division multiplexing without changing the optical power splitter between the station side device and the subscriber unit and changing the loss budget allocated to the transmission distance. In addition, it is possible to flexibly cope with an increase in the number of users under the station side device while suppressing an increase in cost.

It is a figure which shows the structure of an optical communication system. It is a figure which shows wavelength arrangement | positioning of a downstream signal and an upstream signal. It is a figure which shows the structure of a wavelength filter. It is a figure which shows the operating principle of a wavelength filter. It is a figure which shows the operation | movement content of a wavelength filter.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

  The configuration of the optical communication system is shown in FIG. The optical communication system S includes a station side device 1, subscriber devices 2-11, ..., 2-j1, ..., 2-n1, ..., a wavelength filter 3, an optical power splitter 4-1,. ..., 4-j, ..., 4-n, optical fibers 5-1, ..., 5-i, ..., 5-m, optical fibers 6-1, ..., 6-j. , ..., 6-n and optical fibers 7-11, ..., 7-j1, ..., 7-n1, .... The station side apparatus 1 is comprised from the optical transmitter-receivers 11-1, ..., 11-i, ..., 11-m.

  The optical transceivers 11-1,..., 11-i,..., 11-m are respectively connected to the optical fibers 5-1,. Connected to the wavelength filter 3. The subscriber devices 2-11, ..., 2-j1, ..., 2-n1, ... are optical fibers 7-11, ..., 7-j1, ..., 7-n1, respectively. Are connected to the optical power splitters 4-1,..., 4-j,. Optical power splitters 4-1,..., 4-j,..., 4-n respectively pass through optical fibers 6-1,. Connected to the wavelength filter 3.

  Here, the subscriber units 2-11,..., 2-j1,..., 2-n1 are optical power splitters 4-1,. It may be connected to the wavelength filter 3 without going through. That is, the subscriber devices 2-11,..., 2-j1,..., 2-n1 respectively replace the optical power splitters 4-1,. Instead, it may be connected to subscriber side ports 3B1,..., 3Bj,. In this case, the subscriber devices 2 located under the subscriber side ports 3B1, ..., 3Bj, ..., 3Bn are respectively connected to the subscriber devices 2-11, ..., 2-j1, ... .., 2-n1 only and only one subscriber unit 2.

  In the following description, an optical signal transmitted from the station apparatus 1 to the subscriber apparatus 2 is a downlink signal, and an optical signal transmitted from the subscriber apparatus 2 to the station apparatus 1 is an uplink signal.

  The station-side device 1 includes optical transceivers 11-1, ..., 11-i, ..., 11-m and a control unit 15. Each optical transceiver 11 includes an optical transmitter 12, an optical receiver 13, and an optical multiplexer / demultiplexer 14. Each subscriber unit 2 includes an optical transmitter 21, an optical receiver 22, an optical multiplexer / demultiplexer 23, and a control unit 24.

The downlink communication will be described. Each optical transmitter 12 transmits a downlink signal having a single wavelength among a plurality of wavelengths at one time. Each optical receiver 22 receives a downstream signal having a single wavelength. Here, each optical transmitter 12 transmits a downlink signal having a single wavelength among a plurality of wavelengths so that each optical receiver 22 receives a downlink signal having one wavelength at one time. Control is performed using the control unit 15. Here, the plurality of wavelengths in the downlink communication direction are n types of λ _d1 ,..., Λ _dn .

The uplink communication will be described. Each optical transmitter 21 transmits an upstream signal having a single wavelength among a plurality of wavelengths at one time. Each optical receiver 13 receives an upstream signal having a single wavelength. Here, in order that each optical receiver 13 receives an upstream signal having one wavelength at one time, each optical transmitter 21 has a timing to transmit an upstream signal having a single wavelength among a plurality of wavelengths. Control is performed using each control unit 24. Here, a plurality of wavelengths for upstream communication direction, lambda _u1, · · ·, a n type lambda _un.

The wavelength arrangement of the downstream signal and upstream signal is shown in FIG. In FIG. 2A, the wavelength λ _d1 ,..., Λ _{dn of the} downstream signal and the wavelengths λ _u1 ,..., Λ _un of the upstream signal are separated by the FSR (Free Spectrum Range) of the wavelength filter 3. Thus, it is possible to pass the downlink signal and the uplink signal through the same port. In FIG. 2A, the wavelength band of the upstream signal is arranged on the shorter wavelength side than the wavelength band of the downstream signal, but the wavelength band of the downstream signal may be arranged on the shorter wavelength side than the wavelength band of the upstream signal. Good. In FIG. 2 (b), by arranging the wavelength lambda _d1 of the downstream signal, ..., lambda _dn and wavelength lambda _u1 of the uplink signal, ..., and lambda _un alternately downlink signal and the same port an uplink signal It is possible to pass through. Each optical multiplexer / demultiplexer 14 and each optical multiplexer / demultiplexer 23 multiplex / demultiplex a downstream signal and an upstream signal.

  The configuration of the wavelength filter 3 is shown in FIG. The wavelength filter 3 includes a wavelength distribution part such as AWG, station side ports 3A1, ..., 3Ai, ..., 3Am and subscriber side ports 3B1, ..., 3Bj, ..., 3Bn. .

  The downlink communication will be described. The station-side ports 3A1, ..., 3Ai, ..., 3Am are connected to the optical transmitters 12-1, ..., 12-i, ..., 12-m, respectively. The subscriber side ports 3B1, ..., 3Bj, ..., 3Bn are connected to the optical receivers 22-11, ..., 22-j1, ..., 22-n1, respectively. The station side ports 3A1,..., 3Ai,..., 3Am and the subscriber side ports 3B1,.

  The uplink communication will be described. The subscriber side ports 3B1, ..., 3Bj, ..., 3Bn are connected to the optical transmitters 21-11, ..., 21-j1, ..., 21-n1, respectively. The station-side ports 3A1, ..., 3Ai, ..., 3Am are connected to the optical receivers 13-1, ..., 13-i, ..., 13-m, respectively. The subscriber-side ports 3B1,..., 3Bj,..., 3Bn and the station-side ports 3A1,.

  The operation principle of the wavelength filter is shown in FIG. The wavelength filter 3 in FIG. 4 includes three station side ports 3A1, 3A2, 3A3 and three subscriber side ports 3B1, 3B2, 3B3. In FIG. 4, the downlink signal will be described, but the same applies to the uplink signal.

Figure 4 (a), the the station side port 3A1, wavelength lambda _d1, lambda _d2, when a downlink signal having a lambda _d3 is inputted from the subscriber side port 3B1,3B2,3B3, respectively wavelengths lambda _d1, lambda _d2 , Λ _d3 is output. In FIG. 4B, when downlink signals having wavelengths λ _d1 , λ _d2 , and λ _d3 are input to the station side port 3A2, the wavelengths λ _d3 and λ _d1 are respectively transmitted from the subscriber side ports 3B1, 3B2, and 3B3. , Λ _d2 is output. In FIG. 4C, when downlink signals having wavelengths λ _d1 , λ _d2 , and λ _d3 are input to the station side port 3A3, the wavelengths λ _d2 and λ _d3 are respectively transmitted from the subscriber side ports 3B1, 3B2, and 3B3. , Λ _d1 is output.

The operation principle of the wavelength filter is almost the same for the upstream signal as for the downstream signal. However, as described with reference to FIG. 2, the wavelengths λ _d1 , λ _d2 , and λ _d3 included in the downlink signal and the wavelengths λ _u1 , λ _u2 , and λ _u3 included in the uplink signal are different from each other.

  The operation content of the wavelength filter is shown in FIG. The wavelength filter 3 in FIG. 5 is the same as the wavelength filter 3 in FIG. In FIG. 5, the downlink signal will be described, but the same applies to the uplink signal. In FIG. 5, the station side device 1 includes three optical transceivers 11-1, 11-2, and 11-3, and the optical communication system S includes three optical power splitters 4-1, 4-2, and 4-. 3 is provided.

In Figure 5 the time shown in (a) t1, the optical transmitter 12-1, a downlink signal having a wavelength lambda _d1, is transmitted to the office side port 3A1. Optical transmitter 12-2, a downlink signal having a wavelength lambda _d2, is transmitted to the office side port 3A2. Optical transmitter 12-3, a downlink signal having a wavelength lambda _d3, is transmitted to the office side port 3A3.

The wavelength filter 3 performs wavelength distribution processing according to the operation principle shown in FIG. Optical power splitters 4-1, the downlink signal having a wavelength lambda _d1, received from the subscriber side port 3B1, transmits to the subscriber device 2 located under. Optical power splitters 4-2, the downlink signal having a wavelength lambda _d3, received from the subscriber side port 3B2, transmits to the subscriber device 2 located under. Optical power splitters 4-3, the downlink signal having a wavelength lambda _d2, received from the subscriber side port 3B3, transmits to the subscriber device 2 located under.

In FIG. 5 (b) time indicated in t2, the optical transmitter 12-1, a downlink signal having a wavelength lambda _d3, is transmitted to the office side port 3A1. Optical transmitter 12-2, a downlink signal having a wavelength lambda _d1, is transmitted to the office side port 3A2. Optical transmitter 12-3, a downlink signal having a wavelength lambda _d2, is transmitted to the office side port 3A3.

The wavelength filter 3 performs wavelength distribution processing according to the operation principle shown in FIG. Optical power splitters 4-1, the downlink signal having a wavelength lambda _d2, received from the subscriber side port 3B1, transmits to the subscriber device 2 located under. Optical power splitters 4-2, the downlink signal having a wavelength lambda _d1, received from the subscriber side port 3B2, transmits to the subscriber device 2 located under. Optical power splitters 4-3, the downlink signal having a wavelength lambda _d3, received from the subscriber side port 3B3, transmits to the subscriber device 2 located under.

At time t3 shown in FIG. 5 (c), the optical transmitter 12-1, a downlink signal having a wavelength lambda _d2, it is transmitted to the office side port 3A1. Optical transmitter 12-2, a downlink signal having a wavelength lambda _d3, is transmitted to the office side port 3A2. Optical transmitter 12-3, a downlink signal having a wavelength lambda _d1, is transmitted to the office side port 3A3.

The wavelength filter 3 performs wavelength distribution processing according to the operation principle shown in FIG. Optical power splitters 4-1, the downlink signal having a wavelength lambda _d3, received from the subscriber side port 3B1, transmits to the subscriber device 2 located under. Optical power splitters 4-2, the downlink signal having a wavelength lambda _d2, received from the subscriber side port 3B2, transmits to the subscriber device 2 located under. Optical power splitters 4-3, the downlink signal having a wavelength lambda _d1, received from the subscriber side port 3B3, transmits to the subscriber device 2 located under.

The operation content of the wavelength filter is almost the same for the upstream signal as for the upstream signal. However, as described with reference to FIG. 2, the wavelengths λ _d1 , λ _d2 , and λ _d3 included in the downlink signal and the wavelengths λ _u1 , λ _u2 , and λ _u3 included in the uplink signal are different from each other.

  4 and 5, the case where m = n = 3 has been described. However, the size of m and n is not limited to only when m = n = 3. However, each optical transmitter 12 controls the timing of transmitting a downlink signal having a single wavelength among a plurality of wavelengths so that each optical receiver 22 receives a downlink signal having one wavelength at one time. To do. And each optical transmitter 21 controls the timing which transmits the upstream signal which has a single wavelength among several wavelengths so that each optical receiver 13 may receive the upstream signal which has one wavelength at one time. To do.

  As described above, since the wavelength filter 3 has circularity with respect to the wavelength of the downlink or uplink signal, the optical communication system S can perform downlink or uplink communication using a small number of wavelengths. Therefore, the cost increases to increase the number of users under the station side apparatus 1 without changing the optical power splitter 4 between the station side apparatus 1 and the subscriber apparatus 2 and changing the loss budget allocated to the transmission distance. It is possible to respond flexibly while suppressing this.

  Since a downlink or uplink signal having one wavelength is received at one time, it is possible to provide a PON that effectively combines time division multiplexing and wavelength division multiplexing in downlink or uplink communication. Furthermore, since the optical power splitter 4 is arranged, it is possible to cope with an increase in the number of users under the station side device 1.

In the embodiment, the station side apparatus 1 includes a plurality of optical transceivers 11. However, as a modification, the station side apparatus 1 may include one optical transceiver 11. For example, one optical transmitter 12 transmits a downlink signal having the wavelength λ _d1 to the subscriber apparatus 2-11 at time t1, and transmits a downlink signal having the wavelength λ _d2 to the subscriber apparatus 2-j1 at time t2. Just send it to. For example, the one optical receiver 13 receives the uplink signal having the wavelength λ _u1 from the subscriber device 2-11 at the time t1, and receives the uplink signal having the wavelength λ _u2 at the time t2. Can be received from.

  The optical communication system and the transmission / reception method of the optical communication system according to the present invention can be applied to an optical communication system that is required to have a large capacity, advancement, and economy.

S: Optical communication system 1: Station side device 2: Subscriber device 3: Wavelength filter 4: Optical power splitter 5, 6, 7: Optical fiber 11: Optical transceiver 12: Optical transmitter 13: Optical receiver 14: Optical coupling Demultiplexer 15: Control unit 21: Optical transmitter 22: Optical receiver 23: Optical multiplexer / demultiplexer 24: Control unit

Claims (10)

A station side device having one or a plurality of optical transmitters each transmitting a downstream signal having a single wavelength among a plurality of wavelengths at one time;
A plurality of subscriber units each receiving a downstream signal having a single wavelength;
One or a plurality of station-side ports connected to each of the one or a plurality of optical transmitters and a plurality of subscriber-side ports connected to each of the plurality of subscriber devices; A wavelength filter having circularity with respect to the wavelength of the downstream signal by the side port and the plurality of subscriber side ports;
An optical communication system comprising:   Each optical transmitter controls the timing of transmitting a downlink signal having a single wavelength among a plurality of wavelengths so that each subscriber unit receives a downlink signal having one wavelength at one time. The optical communication system according to claim 1, wherein: A plurality of subscriber units each transmitting an upstream signal having a single wavelength among a plurality of wavelengths at one time; and
A station side device having one or a plurality of optical receivers each receiving an upstream signal having a single wavelength;
A plurality of subscriber-side ports connected to each of the plurality of subscriber devices and one or a plurality of station-side ports connected to each of the one or more optical receivers; A wavelength filter having circularity with respect to the wavelength of the upstream signal by the port and the one or more station-side ports;
An optical communication system comprising:   Each subscriber unit controls the timing of transmitting an uplink signal having a single wavelength among a plurality of wavelengths so that each optical receiver receives an uplink signal having one wavelength at one time. The optical communication system according to claim 3, wherein:   At least one subscriber-side port among the plurality of subscriber-side ports is connected to an optical power splitter, and the optical power splitter is connected to a plurality of the plurality of subscriber devices. The optical communication system according to claim 1. Each of one or a plurality of optical transmitters of the station side device transmits a downlink signal having a single wavelength among a plurality of wavelengths to a plurality of subscriber devices at one time,
The wavelength filter has one or more station-side ports connected to each of the one or more optical transmitters and a plurality of subscriber-side ports connected to each of the plurality of subscriber devices. Alternatively, the plurality of station-side ports and the plurality of subscriber-side ports have circulatory properties with respect to the wavelength of the downlink signal,
Each of the plurality of subscriber apparatuses receives a downlink signal having a single wavelength among a plurality of wavelengths from the station-side apparatus.   Each optical transmitter controls the timing of transmitting a downlink signal having a single wavelength among a plurality of wavelengths so that each subscriber unit receives a downlink signal having one wavelength at one time. The transmission / reception method of an optical communication system according to claim 6. Each of the plurality of subscriber devices transmits an upstream signal having a single wavelength among a plurality of wavelengths to the station side device having one or a plurality of optical receivers at one time,
The wavelength filter has a plurality of subscriber-side ports connected to each of the plurality of subscriber devices and one or a plurality of station-side ports connected to each of the one or more optical receivers. The subscriber-side port and the one or more station-side ports have circularity with respect to the wavelength of the upstream signal,
Each of the one or a plurality of optical receivers receives an uplink signal having a single wavelength among a plurality of wavelengths from the plurality of subscriber apparatuses.   Each subscriber unit controls the timing of transmitting an uplink signal having a single wavelength among a plurality of wavelengths so that each optical receiver receives an uplink signal having one wavelength at one time. The transmission / reception method for an optical communication system according to claim 8, wherein:   At least one subscriber-side port among the plurality of subscriber-side ports is connected to an optical power splitter, and the optical power splitter is connected to a plurality of the plurality of subscriber devices. The transmission / reception method of the optical communication system according to claim 6.

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