JP6748042B2 - Band unused period detection device, subscriber line terminal device, and band unused period detection method - Google Patents

Description

The present invention relates to a band unused period detection device, a subscriber line terminal device, and a band unused period detection method.

There is a method of separately installing an RRH (Remote Radio Head) which is an antenna unit of a radio base station and a BBU (Base Band Unit) which is a signal processing unit. In this method, for example, a communication system 1000 as shown in FIG. 10 is applied. The communication system 1000 includes a BBU 700, RRH 701, RRH 702, and optical devices 600, 601, 602. Each of the BBU 700, the RRH 701, and the RRH 702 is connected to the optical devices 600, 601, 602 that perform optical communication. Further, each of the optical devices 601 and 602 and the optical device 600 are connected by optical fibers 901 and 902.

The RRHs 701 and 702 form small cells 801 and 802, respectively, and perform wireless communication with wireless terminal devices 851 and 852 existing in the small cells 801 and 802. The RRHs 701, 702 transmit the signals received from the terminal devices 851, 852 to the BBU 700 via the optical device 600, and transmit the signals transmitted by the BBU 700 to the terminal devices 851, 852.

In the communication system 1000, a section of optical communication is called a mobile front haul (MFH). If the Wavelength Division Multiplexing (WDM) method, which uses different wavelengths for the uplink and downlink, is used for the mobile fronthaul, it is possible to transmit and receive uplink and downlink signals at the same time with a single optical fiber. (See, for example, Non-Patent Document 1).

As a method when the RRHs 701 and 702 perform wireless communication with the terminal devices 851 and 852 in the small cells 801, 802, a frequency division duplex (FDD) method and a time division duplex method (Time Division Duplex) are used. : TDD) are used. The FDD method is a method that uses different frequency bands in the uplink and the downlink, and the TDD method is a method that uses signals that share the frequency band in the uplink and downlink and are orthogonal on the time axis.

For example, in LTE (Long Term Evolution), seven types of TDD frame formats are used that differ in the ratio of upstream and downstream signals used when applying the TDD scheme. By switching and applying this frame format according to the traffic of the uplink and the downlink, it is possible to flexibly set the ratio of the communication time of the uplink and the downlink (for example, see Non-Patent Document 2). ).

FIG. 11 is a diagram showing a data transmission state in the wireless section and the optical section when the TDD wireless base station is accommodated in the mobile front hall. The distribution diagram of FIG. 11A is a diagram showing a data transmission state in the wireless section, and the distribution diagram of FIG. 11B is a diagram showing an uplink and downlink transmission state of the data in the optical section. The sections indicated by the symbols D1, D2, and D3 are the sections in which downlink signals (hereinafter referred to as "downlink signals") are transmitted, and the sections indicated by the symbols U1 and U2 are uplink signals (hereinafter referred to as "uplink signals"). Is said to be transmitted).

As shown in FIG. 11, since data is transmitted orthogonally to the uplink and downlink in the wireless section on the time axis, only one of the up signal and the down signal is transmitted at any time. become. Even in the optical section, the orthogonal relationship on the time axis is maintained and transmitted. Therefore, when the WDM method is applied in the optical section and different wavelengths are applied to the uplink and downlink, a period in which data transmission is not performed in each wavelength, that is, a period in which the band is unused occurs. In the following description, a band unused period is referred to as a TDD non-transmission period, and a band used period is referred to as a TDD transmission period.

For example, as shown in FIG. 11(B), when the wavelength λ1 is applied to the downlink and the wavelength λ2 is applied to the uplink, in the wavelength λ1, the period from t1 to t2 and t3 to t4 is the TDD non-transmission period. Become. Further, at the wavelength λ2, the TDD non-transmission period is from t0 to t1, t2 to t3, and t4 to t5.

A technique for accommodating the mobile front hall by a PON (Passive Optical Network) is known (see, for example, Patent Documents 1 and 2 and Non-Patent Document 3). FIG. 12 is a block diagram showing an example of a communication system 1000a in which a mobile front hall is accommodated by PON. In the communication system 1000a, each of the RRHs 701, 702, 703 is connected to an ONU (Optical Network Unit: Subscriber Line Termination Unit) 611, 612, 613.

The BBU 700 is connected to an OLT 610 (Optical Line Terminal). Each of the ONUs 611, 612, 613 is connected to the optical fibers 901, 902, 903, and the OLT 610 is connected to the optical fiber 900. The optical fiber 900 and the optical fibers 901, 902, 903 are connected by an optical splitter 950.

For example, when the ONUs 611 to 613 are connected to the OLT 610, the ONU 619 may newly request the connection. When the operating OLT 610 accommodates the ONU 619 that requests a new connection, a process called activation is performed. When performing the activation process, as shown in FIG. 13, the OLT 610 provides a period called a discovery window. In FIG. 13, only the ONU 611 is explicitly shown as the ONU connected to the OLT 610.

The period of the discovery window is a period for accepting a new connection request, and the ONU 619 requesting the new connection can send the new connection request frame 699-new to the OLT 610 during the period of the discovery window. When receiving the new connection request frame 699-new, the OLT 610 authenticates and registers the ONU 619 that has transmitted the new connection request frame 699-new. The discovery window is provided every designated cycle, for example, once every 100 ms (milliseconds), or once every 10 seconds, and so on.

International Publication No. 2014/077168 JP, 2016-146585, A

"Technical Basic Course [GE-PON Technology], What is the 1st PON", NTT Technology Journal, [online], 2005, Nippon Telegraph and Telephone Corporation, [September 7, 2017 search], Internet <URL : Http://www.ntt.co.jp/journal/0508/files/jn200508071.pdf> 3GPP, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 12)”, 3GPP TS 36.300(V12.4.0), December 2014 Daisuke Hisano, Takayuki Kobayashi, Member, IEEE, Hiroshi Ou, Tatsuya Shimada, Hiroyuki Uzawa, Jun Terada, and Akihiro Otaka, “TDM-PON for Accommodating TDD-Based Fronthaul and Secondary Services”, JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 35, NO. 14, JULY 15, 2017, pp2788-2796

However, while the discovery window is being executed, the connected ONUs 611 to 613 are not given the opportunity to transmit signals in the upstream direction. For example, FIG. 13 is a diagram showing a transmission state of an upstream frame in the PON. Reference numerals 691-1 to 691-1 indicate upstream frames transmitted by the ONU 611, reference numerals 692-1 to 692 indicate upstream frames transmitted by the ONU 612, and reference numerals 693-1 to 69-3 indicate The upstream frame transmitted by the ONU 613 is shown.

As shown in FIG. 13, when the discovery window is provided in the second upstream transmission cycle T, the ONU 611 is not given the opportunity to transmit the upstream frame. Therefore, the ONU 611 queues the frame 691-2 in the transmission buffer, and the frame stays in the ONU 611. As a result, a delay occurs in the ONU 611, and there is a problem that it is not possible to satisfy the requirement regarding the delay in the mobile fronthaul, that is, the delay in the communication between the RRH 701 connected to the ONU 661 and the BBU 700.

In order to solve this problem, for example, as shown in FIG. 14, a downlink period in a radio section of t0 to t1, t2 to t3, and t4 to t5 in FIG. It is conceivable to provide a discovery window in the TDD non-transmission period. In the case of this method, a means for discriminating between the TDD non-transmission period and the TDD transmission period is required in order to provide the discovery window in the TDD non-transmission period. For example, Patent Document 2 and Non-Patent Document 3 show means for detecting a TDD non-transmission period using a traffic monitor. In FIG. 14, only the ONU 611 is explicitly shown as the ONU connected to the OLT 610.

However, the method disclosed in Patent Document 2 estimates the TDD non-transmission period based on the traffic amount acquired by the traffic monitor by utilizing the periodicity in which traffic occurs. Therefore, there is a problem that the TDD non-transmission period cannot be accurately detected unless there is some traffic.

Further, in the method shown in Non-Patent Document 3, the TDD non-transmission period is estimated by using the test pattern of the upstream signal. Therefore, in the case where this test pattern cannot be transmitted, for example, when the administrator cannot immediately transmit the test pattern due to operation or the like, there is a problem that the TDD non-transmission period cannot be detected. is there.

In view of the above circumstances, an object of the present invention is to provide a technique capable of detecting a band unused period of an upstream signal at an arbitrary timing.

According to one aspect of the present invention, a subscriber line terminating device connected to a terminal device and a communication device for performing time division duplex communication, and a subscriber line terminal station connected to the subscriber line terminating device via an optical fiber. An optical transmission system, which comprises a device, wherein an upstream optical signal and a downstream optical signal are multiplexed at different wavelengths, and a communication system for relaying communication between a host device connected to the subscriber line terminal device and the communication device. Is a band unused period detection device used for, linking information generated based on scheduling information of signals transmitted and received between the host device and the communication device, wherein the optical transmission system allocates a band. Acquiring the cooperation information used when performing, the information indicating the period allocated to the transmission of the signal obtained from the acquired cooperation information is arranged in time series on the time axis as the transmission period pattern of the signal, and the time The axis is divided based on the length of the frame used in the time division duplex method, the divided time axes are overlapped to generate a data set, the data set, and the predetermined time. A frame format detection unit that detects information about the frame format corresponding to the data set, and information about the frame format detected by the frame format detection unit based on information about a plurality of frame formats of the division duplex system. Based on the unused period calculation unit for calculating a band unused period in the optical transmission system, a reference time obtained from the cooperation information first acquired by the data set generation unit, and the unused period calculation unit calculates A band unused period detection unit that calculates a band allocation period in the band unused period based on the band unused period information and outputs the band period to the subscriber line terminal device. It is a device.

One aspect of the present invention is the band unused period detection device described above, wherein the registration period calculation unit generates the data set when the unused period calculation unit calculates the band unused period of an upstream signal. When the period allocated to the transmission of the uplink signal obtained from the new cooperation information acquired by the unit is included in the band unused period of the uplink signal, the period to allocate the band in the band unused period of the uplink signal When the unused period calculation unit calculates the band unused period of the downlink signal, the unused period calculation unit is assigned to the transmission of the downlink signal obtained from the new cooperation information acquired by the data set generation unit. When the current period is included in the band unused period of the downlink signal, the calculation of the period in which the band is allocated in the band unused period of the downlink signal ends.

One aspect of the present invention is the band unused period detection apparatus described above, wherein the frame format detection unit is assigned to an upstream signal transmission pattern included in the data set and an upstream signal of the frame format. A calculation method for performing a cross-correlation calculation based on a period pattern, a cross-correlation calculation based on the transmission pattern of the downlink signal included in the data set, and a period pattern assigned to the downlink signal of the frame format. And a calculation method for performing a cross-correlation calculation based on the transmission patterns of the upstream signal and the downstream signal included in the data set and the pattern of the period allocated to the upstream signal and the downstream signal of the frame format. By performing any one of the above calculation methods, the information regarding the frame format corresponding to the data set is detected.

One aspect of the present invention is the band unused period detection device, wherein the data set generation unit includes the uplink signal included in the cooperation information as information indicating a period allocated for transmission of the signal. Of the allocation start time of the acquired uplink signal is arranged in time series on the time axis, or the cooperation information is acquired as information indicating a period allocated to the transmission of the signal. The time assigned to the downlink signal is acquired, and the time assigned to the acquired downlink signal is arranged in time series on the time axis, or the allocation start time of the uplink signal and the downlink are acquired. The times assigned to the signals are arranged in time series on the time axis.

One aspect of the present invention is the band unused period detection apparatus, wherein the optical transmission system is a PON system, and the unused period calculation unit is based on the frame format detected by the frame format detection unit. Based on this, the band unused period of the upstream signal in the PON system is calculated, and the registration period calculation unit receives the new connection request transmitted by the subscriber line terminating device newly connected to the PON system. A new connection request acceptance period for registration is calculated based on the reference time and the band unused period of the upstream signal calculated by the unused period calculation unit, and information on the calculated new connection request acceptance period is calculated. Output to the subscriber line terminal device.

According to one aspect of the present invention, a subscriber line terminating device connected to a terminal device and a communication device for performing time division duplex communication, and a subscriber line terminal station connected to the subscriber line terminating device via an optical fiber. An optical transmission system, which comprises a device, wherein an upstream optical signal and a downstream optical signal are multiplexed at different wavelengths, and a communication system for relaying communication between a host device connected to the subscriber line terminal device and the communication device. A subscriber line terminal device used for, linking information generated based on scheduling information of signals transmitted and received between the host device and the communication device, wherein the optical transmission system allocates a band. Acquiring the cooperation information used when performing, the information indicating the period allocated to the transmission of the signal obtained from the acquired cooperation information is arranged in time series on the time axis as the transmission period pattern of the signal, and the time The axis is divided based on the length of the frame used in the time division duplex method, the divided time axes are overlapped to generate a data set, the data set, and the predetermined time. A frame format detection unit that detects information about the frame format corresponding to the data set, and information about the frame format detected by the frame format detection unit based on information about a plurality of frame formats of the division duplex system. Based on the unused period calculation unit for calculating a band unused period in the optical transmission system, a reference time obtained from the cooperation information first acquired by the data set generation unit, and the unused period calculation unit calculates Based on the information of the band unused period, a registration period calculation unit that calculates a period for allocating a band in the band unused period, and a period for allocating the band calculated by the registration period calculation unit. Is a subscriber line terminal station device including:

One aspect of the present invention is the subscriber line terminal device described above, wherein, when the band allocation processing unit is allocating a band of the uplink signal, the band is obtained from the newly acquired cooperation information. If the period allocated to the transmission of the uplink signal is included in the period to allocate the band in the uplink direction, or if the band of the downlink signal is allocated, from the newly acquired cooperation information When the period allocated to the obtained transmission of the downlink signal is included in the period to allocate the band in the downlink direction, the band allocation is terminated.

According to one aspect of the present invention, a subscriber line terminating device connected to a terminal device and a communication device for performing time division duplex communication, and a subscriber line terminal station connected to the subscriber line terminating device via an optical fiber. An optical transmission system, which comprises a device, wherein an upstream optical signal and a downstream optical signal are multiplexed at different wavelengths, and a communication system for relaying communication between a host device connected to the subscriber line terminal device and the communication device. A method of detecting a band unused period, which is link information generated based on scheduling information of a signal transmitted/received between the host device and the communication device, wherein the optical transmission system allocates a band. Acquiring the cooperation information used when performing, the information indicating the period allocated to the transmission of the signal obtained from the acquired cooperation information is arranged in time series on the time axis as the transmission period pattern of the signal, and the time The axis is divided based on the length of the frame used in the time division duplex method, the divided time axes are overlapped to generate a data set, and the generated data set and the predetermined time division duplex Based on the information of a plurality of frame formats of the system, the information about the frame format corresponding to the data set is detected, and the band unused period in the optical transmission system is calculated based on the detected information about the frame format. Then, based on the reference time obtained from the cooperation information first obtained, and the information of the calculated band unused period, in the band unused period detection method for calculating the period to allocate the band in the band unused period is there.

According to the present invention, it becomes possible to detect an unused period of an upstream signal band at an arbitrary timing.

It is a block diagram which shows the communication system in 1st Embodiment. It is a figure which shows the band allocation start time in 1st Embodiment. It is a block diagram which shows the internal structure of OLT in 1st Embodiment, and the connection relationship of OLT, a cooperation connection apparatus, and BBU. It is a figure which shows the table of a TDD frame format in 1st Embodiment. It is a flow chart which shows a flow of processing of a band unused period detecting device in a 1st embodiment. It is a figure which shows the production|generation process of the data set in 1st Embodiment. 6 is a flowchart (No. 1) showing an exceptional process in the first embodiment. 6 is a flowchart (No. 2) showing an exceptional process in the first embodiment. It is a block diagram which shows the internal structure of OLT in 2nd Embodiment, and the connection relationship of OLT, a cooperation connection apparatus, and BBU. It is a block diagram which shows an example of a structure of a mobile front hall. It is a figure which shows the transmission state of the up signal and the down signal in a mobile fronthaul. It is a block diagram which shows an example of the structure which applied PON in the optical transmission system of a mobile fronthaul. It is a figure (1) which shows the influence on the transmission by a discovery window. It is a figure (2) which shows the influence on the transmission by a discovery window.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a communication system 1 in the first embodiment. The communication system 1 adopts a PON system as a mobile front hall, and the PON system is configured to relay communication between the BBU 200 and the RRHs 210-1 to RRH210-N.

The PON system includes an OLT 100, ONUs 110-1 to 110-N, an optical splitter 120, an optical fiber 130, and optical fibers 131-1 to 131-N. The optical splitter 120 is an optical multiplexer/demultiplexer that connects the optical fiber 130 and the optical fibers 131-1 to 131-N. The optical splitter 120 demultiplexes the signal transmitted from the OLT 100 and outputs the demultiplexed signal to all the ONUs 110-1 to 110-N connected via the optical fibers 131-1 to 131-N. Output. Further, the optical splitter 120 multiplexes the signals transmitted from the respective ONUs 110-1 to 110-N and outputs the multiplexed signal to the OLT 100. The optical fiber 130 connects the OLT 100 and the optical splitter 120. The optical fibers 131-1 to 131-N connect the optical splitter 120 and the ONUs 110-1 to 110-N.

The OLT 100 is a subscriber line terminal device that terminates the ONUs 110-1 to 110-N. The downstream signal transmitted by the OLT 100 is demultiplexed by the optical splitter 120 and reaches all the ONUs 110-1 to 110-N.
The ONUs 110-1 to 110-N are subscriber line termination devices. The ONUs 110-1 to 110-N take in the data addressed to their own devices and output the taken-in data to the RRHs 210-1 to 210-N connected to each. The upstream signals transmitted by the ONUs 110-1 to 110-N are multiplexed by the optical splitter 120 and reach the OLT 110.

The BBU 200 corresponds to a signal processing unit of a wireless base station and corresponds to a higher-level device in the communication system 1. The BBU 200 connects to the OLT 100.
The RRHs 210-1 to 210-N correspond to the antenna unit of the radio base station. The RRHs 210-1 to 210-N are TDD communication devices, for example. Each of the RRHs 210-1 to 210-N is connected to the ONUs 110-1 to 110-N. Each of the RRHs 210-1 to 210-N forms the small cells 300-1 to 300-N, and the terminal device 400-1-1 that transmits and receives radio signals existing in the formed small cells 300-1 to 300-N. To 400-N-1 to transmit and receive wireless signals according to the TDD method. A plurality of terminal devices 400-1-1 to 400-N-1 may be present in each small cell 300-1 to 300-N.

The ONU 110-new connected to the RRH 210-new is in a state of newly making a connection request to the OLT 100. That is, the ONU 110-new is physically connected to the OLT 100 via the optical fiber 131-new connected to the optical splitter 120, but is in a state in which the ONU 110-new is authenticated and not registered by the OLT 100.

In a general PON communication method, for upstream signals from the ONUs 110-1 to 110-N to the OLT 100, a method called DBA (Dynamic Bandwidth Allocation) is used for band allocation for each of the ONUs 110-1 to 110-N. It is used. In the DBA, each of the ONUs 110-1 to 110-N first notifies the OLT 100 of the amount of upstream data. The OLT 100 performs the procedure of allocating the transmission time and the transmission permission amount to each of the ONUs 110-1 to 110-N based on the notification.

As for the downlink signal from the OLT 100 to the ONUs 110-1 to 110-N, the OLT 100 includes one piece of data of each of the ONUs 110-1 to 110-N in one frame in a time division multiplexing method, and thus the transmission is performed. It doesn't take much time. On the other hand, for the upstream signal, a large amount of time is required for the transmission time because the OLT 100 allocates the band after receiving the notification by the above DBA. Therefore, it is difficult to satisfy the requirement for the delay between the BBU 200 and the RRHs 210-1 to 210-N for the upstream signal.

When the technique described in Patent Document 1 described above is applied, the BBU 200 performs scheduling of uplink signals from the RRHs 210-1 to 210-N to the BBU 200 in advance in order to satisfy the requirement. The BBU 200 generates and outputs scheduling information including information on radio resources assigned to the RRHs 210-1 to 210-N by the scheduling.

The OLT 100 uses the scheduling information to determine the allocation start time and the allocation data amount of the uplink signal band for the ONUs 110-1 to 110-N in the PON section. Here, the bandwidth allocation start time refers to, for example, as shown in FIG. 2, when the RRH 210-i is connected to the ONU 110-i (i is an arbitrary number from 1 to N), the RRH 210 -I is the time at which the received wireless signals are collectively demodulated and output to the ONU 110-i is started.

Since the OLT 100 obtains the allocation start time and allocation data amount of the uplink signal band, the allocation start time and allocation data amount of the uplink signal can be determined without waiting for the notification from the ONUs 110-1 to 110-N. Therefore, the delay time relating to the upstream signal can be shortened and the requirement condition for the delay between the BBU 200 and the RRHs 210-1 to 210-N can be satisfied.

In the present embodiment, in the technique described in Patent Document 1, cooperation information used for cooperation of processing between the BBU 200 and the OLT 100 and cooperation information generated based on scheduling information is used. The cooperation information is information including the allocation start time of the uplink signal and the allocation data amount.

FIG. 3 is a block diagram showing the internal configuration of the OLT 100, the connection relationship between the OLT 100 and the BBU 200, and the connection relationship between the OLT 100, the BBU 200, and the cooperative connection device 180. In FIG. 3, the solid line indicates the control signal transmission path, the dotted line indicates the downlink signal transmission path, and the alternate long and short dash line indicates the uplink signal transmission path.

As described above, the BBU 200 performs scheduling of uplink signals from the RRHs 210-1 to 210-N to the BBU 200 in advance to generate scheduling information, and outputs the generated scheduling information to the cooperative connection device 180. Further, the BBU 200 includes an interface (hereinafter referred to as “IF” (Interface)) 200i-u that receives an upstream signal and an IF 200i-d that transmits a downstream signal. The IF 200i-u and the IF 200i-d are different from each other. , And are connected to the IF 70i-1 and IF 71i-1 of the OLT, respectively.

The cooperative connection device 180 converts the scheduling information output by the BBU 200 into information on the allocation start time and allocation data amount of the uplink signal for each of the ONUs 110-1 to 110-N to generate cooperation information. Further, the cooperation connection device 180 outputs the generated cooperation information to the OLT 100 via the IF 80 of the OLT 100.

The OLT 100 includes a band unused period detection device 10, a band allocation processing unit 30, a downlink frame processing unit 40, an uplink frame processing unit 50, an E/O (Electrical/Optical) conversion unit 61, and an O/E (Optical/Electrical) conversion. The unit 62, L2SW (Layer 2 Switch) 70, 71, and IF (Interface) 70i-1, 71i-1, 80 are provided.

The band unused period detection device 10 includes a data set generation unit 11, a frame format detection unit 12, a storage unit 13, an unused period calculation unit 14, and a registration period calculation unit 15. The data set generation unit 11 acquires the cooperation information output by the cooperation connection device 180 via the IF 80. In addition, the data set generation unit 11 reads out the allocation start time of the uplink signal included in the acquired cooperation information. Further, the data set generation unit 11 sets the allocation start time of the uplink signal included in the first cooperation information as the reference time, and outputs the information of the reference time to the registration period calculation unit 15.

Further, the data set generation unit 11 sets the reference time as an initial value on the time axis, and arranges the read start times of allocation of the upstream signals in time series on the time axis. Further, the data set generation unit 11 divides the time axis based on the length of the radio frame used in the TDD method, and superimposes the divided time axes to generate a data set. As a result, the data set generated by the data set generation unit 11 shows the pattern of the uplink signal transmission period in the radio frame.

The storage unit 13 stores, for example, the table shown in FIG. 4 in advance. The table shown in FIG. 4 is a table that stores information of seven types of TDD frame formats that are used when the TDD method is applied and have different upstream and downstream ratios. Seven types of TDD frame formats are specified in Non-Patent Document 2. The TDD frame format information includes items of “index”, “switching cycle”, and “subframe number”. In the “index” item, numbers 0 to 6 indicating seven types of TDD frames are written. The “switching cycle” represents the repetition cycle of the up-down link ratio, and for example, a value of “5 ms” or “10 ms” is written in the switching cycle.

The item of “subframe number” is divided into 10 items of 0 to 9 and includes “D”, “U”, and “S” that are information of the type for each TDD subframe obtained by dividing the TDD frame. Either information is written. “D” indicates a downlink subframe, that is, a subframe in which a downlink signal is transmitted. “U” indicates an uplink subframe, that is, a subframe in which an uplink signal is transmitted. “S” is a special subframe, which is a frame including a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS).

When the "index" is 0, 1, 2, 6, the special subframe "S" is inserted every 5 ms as in the "switching cycle", and when the "index" is 3, 4, 5 , The special subframe “S” is inserted every 10 ms as in the “switching cycle”.

In LTE, as shown in Non-Patent Document 2, the length of one TDD subframe is defined as 1 ms, and one subframe is the minimum time unit for scheduling. This unit is indicated as TTI (Transmission Time Interval). For example, the period from the band allocation start time described with reference to FIG. 2 until 1 TTI elapses is defined as an uplink TDD transmission period.

The frame format detection unit 12 calculates the cross-correlation based on the transmission period pattern of the upstream subframe of the data set generated by the data set generation unit 11 and the TDD frame format stored in the storage unit 13. .. Further, the frame format detection unit 12 outputs information regarding the TDD frame format having the highest degree of similarity, based on the correlation coefficient value obtained by the cross-correlation calculation.

The unused period calculation unit 14 is based on the information about the TDD frame format output from the frame format detection unit 12 and the TDD frame format stored in the storage unit 13, that is, the period of “D”, that is, the downlink subframe. Calculate the period. Further, the unused period calculation unit 14 outputs the calculated period of the subframe in the downlink direction as the TDD non-transmission period of the uplink, that is, the band unused period of the uplink signal.

The registration period calculation unit 15 calculates the period of the activation window based on the information about the unused band period of the uplink signal output by the unused period calculation unit 14 and the reference time information output by the data set generation unit 11. And outputs the information on the calculated period of the activation window to the bandwidth allocation processing unit 30. Note that the activation window has the same meaning as the discovery window described in the background art, and thus a detailed description thereof will be omitted.

The bandwidth allocation processing unit 30 acquires the cooperation information output by the cooperation connection device 180 via the IF 80, and from the acquired cooperation information, information on the allocation start time and allocation data amount of the upstream signal for each ONU 110-1 to 110-N. Read out. The bandwidth allocation processing unit 30 calculates the actual transmission permission amount of the upstream frame based on the read allocation data amount. Further, the band allocation processing unit 30 uses the allocation start time as the transmission start time, generates a transmission permission frame including the transmission start time and the calculated transmission permission amount, and transmits the generated transmission permission frame via the downlink frame processing unit 40. It transmits to ONU110-1 to 110-N.

The bandwidth allocation processing unit 30 also generates a frame including information on the period of the activation window output by the registration period calculation unit 15, and transmits the generated frame to the downlink frame processing unit 40.

The E/O converter 61 is connected to the downlink of the optical fiber 130, converts the downlink electrical signal output by the downlink frame processor 40 into an optical signal, and outputs the optical signal to the downlink of the optical fiber 130. The O/E converter 62 is connected to the uplink of the optical fiber 130, converts the upstream optical signal into an electrical signal, and outputs the electrical signal to the upstream frame processor 50.

The L2SW 70 captures the downlink data transmitted from the BBU 200 to the RRHs 210-1 to 210-N via the IF 70i-1, via the IF 70i-1, and outputs the downlink data to the downlink frame processing unit 40. The L2SW 71 outputs the upstream data transmitted by the RRHs 210-1 to 210-N to the BBU 200, which is output by the upstream frame processing unit 50, to the BBU 200 via the IF 71i-1.

The downlink frame processing unit 40 multiplexes downlink data for each of the ONUs 110-1 to 110-N output from the L2SW 70 by a time division multiplexing method to generate a frame, and the generated frame is sent to the E/O conversion unit 61. Via the ONUs 110-1 to 110-N. Further, the downlink frame processing unit 40 transmits the transmission permission frame output by the band allocation processing unit 30 to the ONUs 110-1 to 110-N. Further, the downlink frame processing unit 40 transmits a frame including the information on the activation window period output from the band allocation processing unit 30 to the unregistered ONU 110-new. The unregistered ONU 110-new receives the frame and transmits a new connection request frame to the OLT 100 during the activation window.

The upstream frame processing unit 50 receives the upstream frame transmitted by the ONUs 110-1 to 110-N via the O/E conversion unit 62. Further, the upstream frame processing unit 50 divides the received upstream frame into frames for each of the ONUs 110-1 to 110-N and outputs the frames to the BBU 200 via the L2SW 71.

(Processing by band unused period detection device)
FIG. 5 is a flowchart showing a flow of processing by the band unused period detection device 10.
The data set generation unit 11 initializes the data set (step S101). The data set generation unit 11 acquires a plurality of pieces of cooperation information output by the cooperation connection device 180 during a predetermined time (step S102).

When the designated time elapses, the data set generation unit 11 reads the information on the allocation start time of the band of the upstream signal from the first cooperation information (step S103). The data set generation unit 11 sets the allocation start time included in the first read cooperation information as the reference time, and outputs the information of the reference time to the registration period calculation unit 15. Further, the data set generation unit 11 writes the information corresponding to the reference time into the initialized data set to generate the data set (step S104).

Here, the data set is, for example, data having an array structure indicated by reference numeral DS1 shown in FIG. The numbers "0" to "19" in the upper part of the data set DS1 are array numbers. In the case of LTE, 1 TTI, which is the length of one subframe, is 1 ms, and the data set DS1 shown in FIG. 6 has a length of 20 ms, that is, the number of arrays capable of storing information of 20 subframes. Have If, in step S102, the data set generation unit 11 acquires the cooperation information for 10 seconds, the required number of data set arrays is 10 s/1 ms=10,000.

The data set DS1 has been initialized by the data set generation unit 11 in the process of step S101, that is, has not been written with information. In the process of step S104, the data set generation unit 11 writes and stores the value of "1" as a flag at the position of the head array element number "0" corresponding to the reference time.

The data set generation unit 11 reads out the allocation start time of the uplink signal band from the next cooperation information (step S105). The data set generation unit 11 calculates the difference between the read allocation start time and the reference time, and writes and stores the flag “1” at the position of the array of the data set DS1 corresponding to the calculated time difference (step S106). For example, as shown in FIG. 6, when the reference time is t0=10 ms and the allocation start time of the second cooperation information is t1=14 ms, the difference is 4 ms. Therefore, the data set generation unit 11 writes the flag “1” at the position “4” of the data set DS1.

It is assumed that the cooperation information can be periodically acquired for each TTI, or can be acquired only randomly. On the other hand, by using the allocation start time included in the cooperation information as described above, by calculating the relative time difference from the reference time, the uplink signal can be transmitted without depending on the output timing of the cooperation information. A pattern of transmission periods can be recorded.

The data set generation unit 11 determines whether or not the processes of steps S105 and S106 have been performed for all the acquired cooperation information (step S107). When the data set generation unit 11 determines that the processes of steps S105 and S106 have not been performed for all the acquired cooperation information (step S107-NO), the process from step S105 is repeated.

On the other hand, when the data set generation unit 11 determines that the processes of steps S105 and S106 have been performed on all the acquired cooperation information (step S107-YES), the data set DS1 is divided into TDD frame lengths, that is, 10 ms. And superimpose them (step S108). For example, as shown in FIG. 6, the data set generation unit 11 divides the data set DS1 into a data set DS2-1 and a data set DS2-2 in units of 10 ms. The data set generation unit 11 generates the data set DS3 by superimposing the head array of the data set DS2-1 and the head array of the data set DS2-2 so as to overlap each other.

At this time, the data set generation unit 11 sets the value of the array in which the flag is written as “1” and the value of the array in which the flag is not written as “0” to perform the logical sum operation, and the result of the logical sum operation The flag "1" is written and stored in the array which has become "1". The data set DS3 finally obtained has a length of 10 ms, which is the same as the TDD frame length. The array in which the flag “1” is written indicates that the transmission period has been assigned to the upstream signal. Since each array shows the period of 1 ms, the data set DS3 shows the pattern of the transmission period of the upstream signal obtained from the plurality of pieces of cooperation information.

The data set generation unit 11 outputs the generated data set DS3 to the frame format detection unit 12. The frame format detection unit 12 calculates the cross-correlation between the data set DS3 output by the data set generation unit 11 and each of the patterns of the upstream signal obtained from the frame format of TDD stored in the storage unit 13 and calculates the phase. Calculate the relationship figures. As the information about the TDD frame format, the frame format detection unit 12 informs the unused period calculation unit 14 of the index value of the TDD frame format having the largest calculated correlation coefficient value and the subframe number which is the head in the TDD frame format. Output (step S109).

An example of the cross-correlation calculation will be described. The beginning of the array of the data set DS3 is always an upstream signal. In order for the frame format detection unit 12 to perform the cross-correlation calculation, for example, in each of the seven TDD frame formats, rearrangement is performed so that the position of “U” is at the head, and all of the “U” are at the head. There is a method of performing a cross-correlation calculation on the pattern.

For example, for a TDD frame whose "index" is "3", the pattern starting with "U" has the following three patterns because the number of "U" is three. That is, these are "UUUDDDDDDS", "UUDDDDDDSU", and "UDDDDDDSUU". The subframe numbers at the beginning of each of the three are “2”, “3”, and “4”.

The frame format detection unit 12 creates a cross-correlation array in which the position of "U" in the pattern generated from the TDD frame format is "1" and the positions of "D" and "S" are "0". The cross-correlation arrays for the three patterns with the index “3” are “1110000000”, “1100000001”, and “10000000011”. The frame format detection unit 12 writes “0” at a position where no value is written in the array of the data set DS3. For example, in the case of the data set DS3 of FIG. 6, the frame format detection unit 12 sets the data set DS3 as an array of “1001110010”.

The frame format detection unit 12 generates a cross-correlation array for all index values “0” to “6”, and performs a cross-correlation calculation with the data set DS3 for each of the generated cross-correlation arrays to calculate the cross-correlation. Calculate the correlation coefficient value for each array. By performing this cross-correlation calculation, the correlation coefficient value of the cross-correlation array in which the position of the flag “1” of the data set DS3 and the position of “U” are the same is the largest. The frame format detection unit 12 outputs the index value of the TDD frame having the maximum correlation coefficient value and the head subframe number when the maximum correlation coefficient value is obtained, to the unused period calculation unit 14.

The unused period calculation unit 14 refers to the storage unit 13 to read the information of the TDD frame format corresponding to the index value output by the frame format detection unit 12, and to determine the subframe number of the subframe number output by the frame format detection unit 12. Rearrange so that the frame is at the top. The unused period calculation unit 14 calculates the position of “D”, that is, the time corresponding to the downlink signal, with the beginning being 0 second, and the calculated time is the downlink TDD transmission period, that is, the uplink TDD non-transmission period. And The unused period calculation unit 14 outputs the calculated uplink TDD non-transmission period to the registration period calculation unit 15 as the band unused period of the uplink signal (step S110).

For example, it is assumed that the frame format detection unit 12 outputs “3” as the index value and “3” as the head subframe number. At this time, the unused period calculation unit 14 rearranges the frame of the index “3” with the subframe number “3” at the beginning to obtain a pattern of “UUDDDDDDSU”. Since it is 1 ms per subframe, the unused period calculation unit 14 determines the downlink TDD transmission time from 2 ms to 8 ms, that is, the uplink TDD non-transmission period, based on the position of “D” in the pattern. Calculate as

The registration period calculation unit 15 is based on the information on the unused band bandwidth of the uplink signal output by the unused period calculation unit 14, the information on the reference time output by the data set generation unit 11, and the predetermined cycle. Calculate the duration of the activation window. The registration period calculation unit 15 outputs information on the calculated period of the activation window to the band allocation processing unit 30 (step S111).

In the configuration of the first embodiment described above, the PON system including the OLT 100 and the ONUs 110-1 to 110-N, in which the upstream optical signal and the downstream optical signal are multiplexed at different wavelengths is the terminal device 400-1- 1-400-N-1 and the RRHs 210-1 to 210-N, which perform TDD communication, and the BBU 200 are relayed. In the band unused period detection device 10 included in the OLT 100, the data set generation unit 11 is cooperation information generated based on scheduling information of signals transmitted and received between the BBU 200 and the RRHs 210-1 to 210-N. The PON system acquires the cooperation information used when allocating the band of the upstream optical signal, and the information indicating the period allocated to the transmission of the upstream signal obtained from the acquired cooperation information is chronologically displayed on the time axis. By arranging them side by side to form an uplink signal transmission period pattern, the time axis is divided based on the length of the frame used in the time division duplex method, and the divided time axes are overlapped to generate a data set. The frame format detection unit 12 detects information on the TDD frame format corresponding to the data set based on the data set and information on a plurality of predetermined TDD frame formats. The unused period calculation unit 14 calculates the band unused period of the upstream signal in the PON system based on the information on the frame format. The registration period calculation unit 15 calculates the uplink signal based on the reference time obtained from the cooperation information first acquired by the data set generation unit 11 and the band unused period information of the uplink signal calculated by the unused period calculation unit. The period during which the band is allocated is calculated in the band unused period. Therefore, it becomes possible to detect the band unused period of the upstream signal at an arbitrary timing without depending on the traffic. This makes it possible to provide the activation window period without affecting the upstream signal transmission period of the ONUs 110-1 to 110-N.

For example, in the techniques disclosed in Patent Document 2 and Non-Patent Document 3, the traffic monitor is used to estimate the uplink TDD non-transmission period from the uplink traffic amount and the test pattern of the uplink signal. On the other hand, in the present embodiment, the data set is generated using the allocation start time of the cooperation information obtained from the scheduling information. Therefore, in the present embodiment, it is possible to obtain the information on the generation timing of the upstream signal without depending on the traffic. As described above, since it is possible to more accurately obtain the information on the generation timing of the uplink signal, it is possible to more accurately determine the downlink TDD transmission time and the uplink TDD non-transmission period.

Since the allocation start time included in the cooperation information indicates the time when allocation is started in the uplink signal, the unallocated time is detected based on the allocation start time, and the detected time is transmitted in the downlink TDD. A method of determining the period is also possible. However, in this method, when an uplink transmission request is not generated, allocation is not performed even in the uplink TDD transmission period, so that the unallocated time is definitely the downlink TDD transmission time. I can't judge. On the other hand, in the present embodiment, the start time of the uplink signal obtained from the plurality of pieces of cooperation information is acquired, and the most similar format is detected from the TDD frame formats. Therefore, the downlink TDD transmission time can be detected according to the TDD frame format, and the uplink TDD non-transmission period can be detected more accurately.

(Exception processing in the first embodiment)
7 and 8 are flowcharts showing the exception processing in the first embodiment. Here, the exceptional process means that the allocation start time of the upstream signal included in the cooperation information newly output by the cooperative connection device 180 is within the band unused period of the upstream signal detected by the band unused period detection device 10. This is processing when it is included. As shown below, there are exception processing by the bandwidth allocation processing unit 30 and exception processing by the registration period calculation unit 15.

(Exception processing by the bandwidth allocation processing unit)
FIG. 7 is a flowchart showing exception processing by the bandwidth allocation processing unit 30. As a premise of the processing shown in FIG. 7, the bandwidth allocation processing unit 30 is performing the bandwidth allocation processing for the activation window period based on the activation window period output by the registration period calculation unit 15. Or the state of being assigned. Further, in the block diagram of FIG. 3, connection lines for transmitting instruction information are provided between the band allocation processing unit 30 and the upstream frame processing unit 50, and between the band allocation processing unit 30 and the band unused period detection device 10. It is assumed to exist.

The bandwidth allocation processing unit 30 acquires the cooperation information output by the cooperation connection device 180 via the IF 80 (step Sa201). The band allocation processing unit 30 reads out the information of the allocation start time of the uplink signal included in the acquired cooperation information. The band allocation processing unit 30 determines whether or not the allocation start time of the read uplink signal is included in the period of the activation window received from the registration period calculation unit 15 (step Sa202).

When the band allocation processing unit 30 determines that the read allocation start time of the uplink signal is not included in the period of the activation window (step Sa202-NO), the process ends. On the other hand, when the band allocation processing unit 30 determines that the allocation start time of the read uplink signal is included in the period of the activation window (step Sa202-YES), the activation process is terminated and a new one is generated. Band allocation processing is performed based on such cooperation information (step Sa203).

If the process is in the process of performing the band allocation process during the activation window, the band allocation processing unit 30 ends its own process. At this time, the band allocation processing unit 30 may initialize the band allocation process.

On the other hand, if the bandwidth of the activation window has already been allocated, it is necessary to perform processing for canceling the period of the activation window. For example, the bandwidth allocation processing unit 30 transmits a notification of canceling the period of the activation window for which the bandwidth is allocated to the ONU 110-new which is requesting a new connection, and transmits a new connection request frame. Try not to let me.

The band allocation processing unit 30 outputs instruction information that causes the band unused period detection device 10 to re-detect the band unused period of the upstream signal (step Sa204). Upon receiving the instruction information, the band unused period detection device 10 performs the process shown in FIG. 5 and outputs the period of the new activation window to the band allocation processing unit 30.

(Exception processing by the registration period calculator)
FIG. 8 is a flowchart showing exceptional processing by the registration period calculation unit 15. As a premise of the processing shown in FIG. 8, the registration period calculation unit 15 performs the calculation process of the activation window period based on the band unused period of the uplink signal output from the unused period calculation unit 14. Suppose that it is in the middle of the process.

While the registration period calculation unit 15 is calculating the period of the activation window based on the band unused period of the upstream signal, the information of the new reference time output by the data set generation unit 11 is acquired (step Sb301). The registration period calculation unit 15 determines whether or not the reference time is included in the band unused period of the upstream signal received from the unused period calculation unit 14 (step Sb302).

When the registration period calculation unit 15 determines that the reference time is not included in the band unused period of the uplink signal (step Sb302-NO), the process ends. On the other hand, when the registration period calculation unit 15 determines that the reference time is included in the band unused period of the upstream signal (step Sb302-YES), the registration period calculation unit 15 determines that the activation window period is reached. Ends (step Sb303). When the unused period calculation unit 14 outputs the information on the band unused period of the new uplink signal, the registration period calculation unit 15 determines the activation window of the activation window based on the band unused period of the new uplink signal. Calculate the period.

By the exceptional processing shown in FIG. 7 and FIG. 8 above, when the band of the upstream signal is assigned by the scheduling by the BBU 200 to the band unused period detected by the band unused period detection device 10, the detected band is not detected. It is possible to forcibly end the usage of the usage period. As a result, it is possible to prevent communication in the mobile fronthaul from being affected.

In the first embodiment, the pattern of the uplink signal transmission period is recorded in the data set DS1 based on the uplink signal allocation start time included in the cooperation information. The present invention is not limited to this embodiment. For example, the period during which the cooperative connection device 180 outputs the cooperative information to the OLT 100 is the period allocated to the downlink signal. Therefore, the time at which the data set generation unit 11 acquires the cooperation information indicates the time assigned to the downlink signal. Therefore, the data set generation unit 11 may generate the data set DS1 by using the time at which the cooperation information is acquired as the downlink signal allocation time, instead of the uplink signal allocation start time included in the cooperation information.

When the time at which the cooperation information is acquired is the downlink signal allocation time, the frame format detection unit 12 sets the position of “D” in the TDD frame format to “1” and the positions of “U” and “S” to “0”. The cross-correlation array described above is generated to perform the cross-correlation calculation. Further, in this case, the data set generation unit 11 outputs the acquisition time of the cooperation information acquired first as the reference time to the registration period calculation unit 15a, and at the same time, the allocation start time of the uplink signal included in the cooperation information acquired first. Is output to the registration period calculation unit 15. The registration period calculation unit 15 calculates the period of the activation window based on the reference time, while at the time of exception processing, the exception processing of step Sb302 of FIG. 8 is performed using the allocation start time of the uplink signal. Will be done.

Further, information on both the allocation start time of the uplink signal and the allocation time of the downlink signal may be used. By doing so, the information of the pattern of the transmission period of the signal can be increased, and therefore the frame format detection unit 12 can perform the cross-correlation calculation based on the patterns of the transmission periods of both the upstream signal and the downstream signal. Thus, it is possible to detect the TDD frame format more accurately.

(Second embodiment)
FIG. 9 is a block diagram showing the configuration of the second embodiment. In FIG. 9, the same configurations as those of the first embodiment are designated by the same reference numerals, and different configurations will be described below. The other-system host device 200a, which is a host device, provides a new communication service by using the band unused period of the upstream signal calculated by the unused period calculator 14, for example.

The OLT 100a includes a band unused period detection device 10a in place of the band unused period detection device 10 included in the OLT 100, and has a configuration in which IFs 70i-2 and 71i-2 are added as interfaces of the L2SWs 70 and 71, respectively. Each of the IFs 70i-2 and 71i-2 is connected to the IFs 200ai-d and 200ai-u of the other system upper apparatus 200a. The band unused period detection device 10a includes a registration period calculation unit 15a in place of the registration period calculation unit 15 included in the band unused period detection device 10.

In addition to the configuration of the registration period calculation unit 15, the registration period calculation unit 15a calculates and calculates a period in which the upstream band is allocated to the other system upper apparatus 200a in the band unused period of the upstream signal. Information indicating the period is output to the band allocation processing unit 30. The band allocation processing unit 30 performs band allocation based on the period in which the upstream band allocated by the registration period calculation unit 15a is allocated. As a result, the other system upper apparatus 200a uses the upstream band allocated by the band allocation processing unit 30 to the terminal devices 400-1-1 to 400-N-1 through the RRHs 210-1 to 210-N. Receives requests related to the communication services it provides.

Note that the unused period calculation unit 14 may be configured to calculate the unused period of the downlink signal in addition to the unused period of the upstream signal band. When calculating the band unused period of the downlink signal, the registration period calculation unit 15a calculates the period to be allocated to the other system upper apparatus 200a in the downlink signal, and the other system upper apparatus 200a uses the period and the terminal device 400 is used. It is also possible to send a request relating to the communication service provided to the 1-1 to 400-N-1.

Also, in the above-described second embodiment, as in the first embodiment, the data set generation unit 11 replaces the allocation start time of the uplink signal included in the cooperation information with the time when the cooperation information is acquired. The data set DS1 may be generated as the signal allocation time. Also in the second embodiment, information on both the allocation start time of the uplink signal and the allocation time of the downlink signal may be used.

Further, similarly in the second embodiment, the exception processing of FIGS. 7 and 8 shown in the first embodiment may be performed. Further, in the second embodiment, the unused period calculation unit 14 may perform exceptional processing shown in FIG. 7 and FIG. 8 when the unused period of the downlink signal is calculated. When the unused period calculation unit 14 performs the exceptional processing of FIGS. 7 and 8 when calculating the unused band of the downlink signal, the time when the band allocation processing unit 30 acquires new cooperation information is the allocation of the downlink signal. It will indicate the time. Therefore, in step Sa202 of FIG. 7, the band allocation processing unit 30 determines whether or not the time is included in the period for allocating the band in the downlink direction received from the registration period calculation unit 15a. Further, in the process of FIG. 8, since the time when the data set generation unit 11 acquires the new cooperation information indicates the allocation time of the downlink signal, in step Sb302 of FIG. 8, the registration period calculation unit 15a It is determined whether or not the acquired time is included in the band unused period of the downlink signal calculated by the unused period calculation unit 14.

In the first and second embodiments described above, when the frame format detection unit 12 calculates the cross-correlation, it rearranges each of the seven TDD frame formats with “U” as the head. , A pattern corresponding to the number of “U”s is generated, but the configuration of the present invention is not limited to this embodiment. For example, in each of the seven TDD frame formats, rearrangement starting from “U” is performed in advance, the position of “U” is set to “1”, and the positions of “D” and “S” are set to “0”. The cross-correlation array may be generated and stored in the storage unit 13.

For example, regarding each index, since there are 6 "U"s in the index "0", 6 patterns are generated. Since there are four "U"s in the index "1", four patterns are generated. Since there are two "U"s at the indexes "2" and "4", two patterns are generated. Since there are three "U"s in the index "3", three patterns are generated. Since there is one "U" in the index "5", one pattern is generated. Since there are 5 "U"s in the index "6", 5 patterns are generated. Then, there are a total of 6+4+2×2+3+1+5=23 patterns. Therefore, 23 cross-correlation arrays are generated in advance, a new index value is given to each of the arrays, and the arrays are stored in the storage unit 13. By doing so, the frame format detection unit 12 does not need to perform rearrangement and can specify the format only by the index value, and therefore outputs the head subframe number to the unused period calculation unit 14. There is no need. The unused period calculation unit 14 can detect the corresponding pattern by referring to the storage unit 13 based on the index value output by the frame format detection unit 12.

The cross-correlation calculation performed by the frame format detection unit 12 is not limited to the above method. For example, a pattern in which the TDD frame format is repeated a certain number of times is generated, a convolution operation is performed on the generated pattern using the data set DS3, and the most similar TDD frame format is calculated based on the magnitude of the peak value. May be detected.

Further, in the first and second embodiments described above, the band unused period of the upstream signal is detected based on the cooperation information for all RRHs 210-1 to 210-N. You may make it detect the band unused period of the upstream signal of all the other RRH210-1 to 210-N based on the cooperation information with respect to one RRH210-i.

In addition, in the first and second embodiments described above, the data set generation unit 11 acquires the cooperation information during a predesignated time, and the more cooperation information to acquire, the more accurate signal transmission. A period pattern will be obtained. On the other hand, since the storage capacity allocated to the band unused period detection devices 10 and 10a is finite, the designated time is limited according to the number of arrays of the data set DS1 that can be secured in the data set generation unit 11. Will be. In addition to the time, the number of pieces of cooperation information and the amount of data may be designated, or a combination of these may be used. It should be noted that the seven TDD frame formats shown in FIG. 4 are not dynamically switched or switched in a short time. For example, the same frame format is used from morning to evening, and the same from the evening to the morning. In the meantime, switching is performed in a long cycle such as switching to another frame format. Therefore, with respect to the predesignated time, the number of cooperation information, and the like, it is possible to select an arbitrary time and number within the cycle in which switching is performed.

Further, in the first and second embodiments, the uplink signal allocation start time included in the cooperation information is used as it is, but a value obtained by adding an offset to the time may be used. The offset may be a fixed value or a value that adaptively changes. Also, when using the time when the cooperation information is acquired, a value to which an offset is added may be used.

Further, in the first and second embodiments described above, the cooperative connection device 180 may be provided outside the OLTs 100 and 100a as shown in FIGS. 3 and 9, or inside the BBU 200. It may be provided, or may be provided inside the OLT 100, 100a. Also, instead of connecting to the OLTs 100 and 100a through physically different IFs 80 as shown in FIGS. 3 and 9, the OLTs 100 and 100a may be connected to each other through virtual or logically separated interfaces. Good.

Further, in the above-described first and second embodiments, the band unused period detection device 10, 10a is provided inside the OLT 100, 100a, but may be provided outside the OLT 100, 100a. It may be provided inside the cooperative connection device 180 or the BBU 200.

Further, in the above-described first and second embodiments, the PON system relays the information transmitted and received by the BBU 200 and the RRHs 210-1 to 210-N, but the present invention is not limited to this embodiment. Absent. The present invention is not limited to the network topology, and an optical transmission system having a network topology such as a ring configuration or a bus configuration may be applied instead of the PON system.

Further, in the above-described first and second embodiments, the scheduling information output by the BBU 200 is information obtained by scheduling uplink signals from the RRHs 210-1 to 210-N to the BBU 200. The configuration is not limited to the embodiment. The scheduling information may be scheduling information obtained by scheduling uplink and downlink signals transmitted and received between the RRHs 210-1 to 210-N and the BBU 200. In that case, the cooperative connection device 180 uses the scheduling information to transmit uplink information. The cooperation information including the signal allocation start time and the allocation data amount will be generated.

Further, in the first and second embodiments described above, the RRHs 210-1 to 210-N and the terminal devices 400-1-1 to 400-N-1 are wirelessly communicated with each other. Any communication method may be used, and a wired communication method may be used.

The band unused period detection devices 10 and 10a and the OLTs 100 and 100a in the above-described embodiments may be realized by a computer. In that case, the program for realizing this function may be recorded in a computer-readable recording medium, and the program recorded in this recording medium may be read by a computer system and executed. The “computer system” mentioned here includes an OS and hardware such as peripheral devices. The "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in a computer system. Further, the "computer-readable recording medium" means that a program is dynamically held for a short time like a communication line when the program is transmitted through a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside the computer system that serves as a server or a client in that case may hold the program for a certain period of time. Further, the program may be for realizing a part of the functions described above, or may be a program that can realize the functions described above in combination with a program already recorded in a computer system, It may be realized by using a programmable logic device such as FPGA (Field Programmable Gate Array).

The embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes a design etc. within the scope not departing from the gist of the present invention.

10... Band unused period detection device, 11... Data set generation unit, 12... Frame format detection unit, 13... Storage unit, 14... Unused period calculation unit, 15... Registration period calculation unit

Claims (8)

A subscriber line terminal device connected to a terminal device and a communication device that performs time division duplex communication, and a subscriber line terminal station device connected to the subscriber line terminal device through an optical fiber are provided. An optical transmission system in which a signal and a downstream optical signal are multiplexed at different wavelengths, a band unused period used in a communication system that relays communication between a host device connected to the subscriber line terminal device and the communication device. A detection device,
The cooperation information generated based on the scheduling information of the signals transmitted and received between the host device and the communication device, which is used when the optical transmission system allocates the band, is acquired and acquired. The information indicating the period allocated to the transmission of the signal obtained from the cooperation information is arranged in time series on the time axis to form the transmission period pattern of the signal, and the time axis of the frame used in the time division duplex method. A data set generation unit that generates data sets by dividing the time axes and overlapping the divided time axes,
A frame format detection unit that detects information regarding the frame format corresponding to the data set based on the data set and information about a plurality of frame formats of the time division duplex system that is predetermined.
An unused period calculation unit that calculates a band unused period in the optical transmission system, based on information about the frame format detected by the frame format detection unit,
A band is allocated in the band unused period based on a reference time obtained from the cooperation information first acquired by the data set generation unit and the band unused period information calculated by the unused period calculation unit. A registration period calculation unit that calculates a period and outputs the period to the subscriber line terminal device;
A band unused period detection device comprising: The registration period calculation unit,
When the unused period calculation unit calculates the band unused period of the uplink signal, the period allocated to the transmission of the uplink signal obtained from the new cooperation information acquired by the data set generation unit is the uplink. When included in the band unused period of the signal, when the calculation of the period to allocate the band in the band unused period of the upstream signal is finished, the unused period calculation unit calculates the band unused period of the downlink signal, When the period allocated to the transmission of the downlink signal obtained from the new cooperation information obtained by the data set generation unit is included in the band unused period of the downlink signal, in the band unused period of the downlink signal The band unused period detection device according to claim 1, wherein the calculation of the period for allocating the band is completed. The frame format detection unit,
A calculation method for performing a cross-correlation calculation based on a transmission pattern of an upstream signal included in the data set and a pattern of a period allocated to the upstream signal of the frame format, the transmission of the downstream signal included in the data set A calculation method for performing a cross-correlation calculation based on a pattern and a pattern of a period allocated to the downlink signal of the frame format, the transmission pattern of the uplink signal and the downlink signal included in the data set, and the frame format Detecting information about the frame format corresponding to the data set by performing one of the calculation methods for performing the cross-correlation calculation based on the pattern of the period allocated to the upstream signal and the downstream signal, The band unused period detection device according to claim 1. The data set generator is
As the information indicating the period allocated to the transmission of the signal, the allocation start time of the uplink signal included in the cooperation information is acquired, and the acquired allocation start time of the uplink signal is arranged in time series on the time axis. Or, as the information indicating the period allocated to the transmission of the signal, the time when the cooperation information is acquired is acquired as the time allocated to the downlink signal, and is allocated to the acquired downlink signal. The time is arranged in time series on the time axis, or the allocation start time of the uplink signal and the time allocated to the downlink signal are arranged in time series on the time axis. A band unused period detecting device according to the item. The optical transmission system is a PON system,
The unused period calculation unit,
Calculating the band unused period of the upstream signal in the PON system based on the frame format detected by the frame format detection unit,
The registration period calculation unit,
The new connection request acceptance period for receiving and registering the new connection request transmitted by the subscriber line terminating device newly connected to the PON system is calculated by the reference time and the unused period calculation unit. The band unused according to any one of claims 1 to 4, wherein the band unused period is calculated based on a signal band unused period and information of the calculated new connection request acceptance period is output to the subscriber line terminal device. Usage period detector. A subscriber line terminal device connected to a terminal device and a communication device that performs time division duplex communication, and a subscriber line terminal station device connected to the subscriber line terminal device via an optical fiber An optical transmission system in which a signal and a downstream optical signal are multiplexed at different wavelengths, and a subscriber line end used in a communication system for relaying communication between a host device connected to the subscriber line terminal device and the communication device A station device,
The cooperation information generated based on the scheduling information of the signals transmitted and received between the host device and the communication device, which is used when the optical transmission system allocates the band, is acquired and acquired. The information indicating the period allocated to the transmission of the signal obtained from the cooperation information is arranged in time series on the time axis to form the transmission period pattern of the signal, and the time axis of the frame used in the time division duplex method. A data set generation unit that generates data sets by dividing the time axes and overlapping the divided time axes,
A frame format detection unit that detects information regarding the frame format corresponding to the data set based on the data set and information about a plurality of frame formats of the time division duplex system that is predetermined.
An unused period calculation unit that calculates a band unused period in the optical transmission system, based on information about the frame format detected by the frame format detection unit,
A band is allocated in the band unused period based on a reference time obtained from the cooperation information initially acquired by the data set generation unit and the band unused period information calculated by the unused period calculation unit. A registration period calculation unit for calculating the period,
A band allocation processing unit for allocating a band based on a period for allocating the band calculated by the registration period calculation unit,
Subscriber line terminal equipment. When the band allocation processing unit is allocating the band of the uplink signal, the band allocated to the transmission of the uplink signal obtained from the newly acquired cooperation information is allocated the band in the uplink direction. When included in the period, or when the bandwidth of the downlink signal is assigned, the period assigned to the transmission of the downlink signal obtained from the newly acquired cooperation information is the downlink direction. 7. The subscriber line terminal device according to claim 6, wherein when the band is included in the period of band allocation, the band allocation is terminated. A subscriber line terminal device connected to a terminal device and a communication device that performs time division duplex communication, and a subscriber line terminal station device connected to the subscriber line terminal device via an optical fiber An optical transmission system in which a signal and a downstream optical signal are multiplexed at different wavelengths, a band unused period performed in a communication system that relays communication between a host device connected to the subscriber line terminal device and the communication device A detection method,
Acquiring cooperation information used when the optical transmission system performs band allocation, which is cooperation information generated based on scheduling information of signals transmitted and received between the host device and the communication device,
Information indicating the period allocated to the transmission of the signal obtained from the obtained cooperation information is arranged in a time series on the time axis as a transmission period pattern of the signal,
Dividing the time axis based on the length of a frame used in the time division duplex method,
Generate the data set by overlapping the divided time axes,
Based on the generated data set and a plurality of frame format information of the predetermined time division duplex method, detecting information about the frame format corresponding to the data set,
Based on the information about the detected frame format, calculate the band unused period in the optical transmission system,
A band unused period detection method for calculating a period for allocating a band in the band unused period, based on a reference time obtained from the initially acquired cooperation information and the calculated information of the band unused period.

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