JP6457372B2 - Transmission system, transmission method, transmission apparatus, and transmission program - Google Patents

Description

  The present invention relates to a transmission system, a transmission method, a transmission apparatus, and a transmission program.

  In a radio communication system, an antenna unit (RRH: Remote Radio Head) and a signal processing unit (BBU: Baseband Unit) of a radio base station may be separated. RRH and BBU communicate via the mobile fronthaul.

  FIG. 11 is a diagram illustrating an example of the configuration of the mobile fronthaul. In the mobile fronthaul, optical wavelength division multiplexing (WDM) communication is used. In the optical wavelength division multiplexing system, the wavelength of light used in the uplink is different from the wavelength of light used in the downlink. The uplink is a link from a lower apparatus such as a mobile radio terminal or RRH to an upper apparatus such as BBU. A downlink is a link from a higher-level device to a lower-level device. The transmission system transmits an uplink data signal and a downlink data signal simultaneously via a single optical fiber by using an optical wavelength division multiplexing system (see Non-Patent Document 1).

  A transmission system may relay a data signal of a communication system based on a TDD (Time Division Duplex) system by an FDD (Frequency Division Duplex) system. In the FDD scheme, different frequency bands are used for uplink and downlink. In the TDD scheme, the same frequency band is used for uplink and downlink. In the TDD scheme, an uplink signal and a downlink signal are switched on the time axis.

  FIG. 12 is a diagram illustrating an LTE (Long Term Evolution) TDD frame. In LTE, seven types of TDD frames are defined. The TDD frame is composed of 10 TDD subframes. In LTE, the time length of the TDD subframe is 1 millisecond. In the TDD scheme, the TDD frame configuration (frame configuration) is determined according to uplink and downlink traffic. The ratio of uplink and downlink communication time can be flexibly changed by determining the frame configuration according to traffic.

  The special subframe (S) includes a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS) (see Non-Patent Document 2). It is a time slot used for transmission of the control signal. UpPTS is a time slot used for transmission of an uplink control signal. GP is a protection time for switching between an uplink signal and a downlink signal.

  FIG. 13 is a diagram illustrating an example of band use in a radio section and an optical section in the mobile fronthaul when accommodating a TDD wireless base station. In the wireless section, a data signal is transmitted by switching between a downlink signal and an uplink signal on the time axis. In the optical section, a data signal is transmitted by switching an uplink signal and a downlink signal on the time axis in accordance with switching in the radio section. Therefore, in the optical section adopting the WDM system, a section (period) on the time axis in which no data signal is transmitted by the TDD system (hereinafter referred to as “TDD non-transmission section”) may occur. That is, the TDD non-transmission period is a data signal transmission stop period (transmission stop period) of the wireless communication system. The TDD non-transmission section occurs in both uplink and downlink.

  There is a transmission system that superimposes a data signal of a mobile system and a data signal of another communication system such as FTTH (Fiber To The Home) in a TDD non-transmission section (see Non-Patent Document 3).

"NTT Technology Journal, Technology Basic Course [GE-PON Technology], 1st PON", [online], 2005, Nippon Telegraph and Telephone Corporation, [Search May 21, 2015], Internet <URL http://www.ntt.co.jp/journal/0508/files/jn200508071.pdf> 3GPP, "Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage2 (Release 12)", 3GPP TR 36.300 (V12.4.0), 2013 (5 Physical (Layer for E-UTRA) Kuno et al., “A study on the same PON accommodation in mobile systems and other communication systems using mobile TDD frame estimation,” Society Conference of IEICE 2015, B-8-10, September 2015.

  FIG. 14 is a diagram illustrating an example of a network system using a PON (Passive Optical Network) in an optical section. An OLT (Optical Line Terminal) (optical subscriber line termination device) is an optical device that estimates a TDD non-transmission section based on a data signal transmitted from a wireless communication system via an optical fiber.

  FIG. 15 is a diagram illustrating an example of the configuration of the OLT. The OLT includes an L2SW, a traffic monitor unit, a time division duplex information estimation unit, a bandwidth allocation unit, and an interface (PON IF).

  FIG. 16 is a flowchart illustrating an example of the operation of the OLT. In the initial state, the OLT assigns a fixed band to the uplink data signal of the wireless communication system. Hereinafter, the fixed bandwidth allocation is referred to as “FBA (Fixed Bandwidth Allocation)”. In the initial state, the OLT stops transmission of data signals of other communication systems.

  The time division duplex information estimation unit estimates the timing of the TDD untransmitted section based on the data amount of the uplink data signal. The time division duplex information estimation unit needs to acquire a data signal of a required traffic amount (hereinafter referred to as “requested traffic amount”) in order to estimate the timing of the TDD untransmitted section. .

  The traffic monitoring unit is configured to transmit an uplink data signal (mobile signal) of the wireless communication system so that the time division duplex information estimation unit can acquire a data signal (traffic information) having a traffic amount greater than or equal to the requested traffic amount. Adjust the length of time to monitor traffic. Note that the traffic monitor unit may monitor an uplink data signal or a downlink data signal.

  The time division duplex information estimation unit determines the timing (usage timing) used by the wireless communication system for data signal transmission. The band allocation unit allocates an uplink data signal of the wireless communication system to a band based on the band allocation method information. The band allocation unit allocates a band to the uplink data signal of the wireless communication system by FBA for a section (period) on the time axis (hereinafter referred to as “TDD transmission section”) in which the data signal is transmitted by the TDD scheme. In the normal state, the bandwidth allocation unit allocates a bandwidth to the data signal of the other communication system for the TDD untransmitted section by FBA or dynamic bandwidth allocation (DBA).

  FIG. 17 is a diagram illustrating an example of a dynamic bandwidth allocation (DBA) algorithm. The horizontal axis indicates time. The upper part shows the operation of dynamic bandwidth allocation performed by the OLT. The lower part shows an operation performed by an ONU (Optical Network Unit) (optical subscriber line network apparatus).

  The ONU buffers uplink data signals. The REPORT signal (transmission request signal) (REPORT frame) is a signal for notifying the data amount of the data signal buffered by the ONU. That is, the REPORT signal is a signal for requesting permission from the OLT to transmit a data signal having the notified data amount. The ONU notifies the OLT of the data amount of the uplink data signal being buffered using the REPORT signal. The OLT calculates a bandwidth to be allocated to the uplink data signal based on the REPORT signal acquired from each ONU. The GATE signal (transmission permission signal) (GATE frame) is a signal for notifying the band allocated to the data signal and the control signal. The OLT determines information indicating a band to be allocated to an uplink data signal (hereinafter referred to as “band allocation information”). The OLT includes band allocation information in the GATE signal. The OLT transmits a GATE signal to each ONU. The OLT also uses the GATE signal to request a REPORT signal from the ONU. Hereinafter, the period of dynamic bandwidth allocation is referred to as “DBA period”. Based on the GATE signal, the ONU determines the time for transmitting the uplink data signal and the data amount of the uplink data signal in the DBA cycle.

  The time division duplex information estimation unit shown in FIG. 15 estimates the configuration of the TDD subframe. The time division duplex information estimation unit determines whether the TDD subframe is allocated to the uplink or the downlink based on the configuration of the TDD subframe. The time division duplex information estimation unit estimates the start time of the TDD subframe. The time division duplex information estimation unit estimates the timing of the TDD untransmitted section based on the start time of the TDD subframe. An ONU connected to another communication system takes a time longer than the DBA cycle from transmitting a REPORT signal to transmitting an uplink data signal.

  FIG. 18 is a time chart showing a first example of traffic. The horizontal axis indicates time. In FIG. 18, the DBA cycle is 1 millisecond. The period of the TDD subframe in the wireless communication system based on LTE is 1 millisecond. The first row from the top shows the division of the structure of the TDD subframe. The second row from the top shows a section in which the OLT acquires a data signal or the like. The third row from the top shows a section in which an ONU connected to another communication system transmits a data signal or the like. The fourth row from the top shows a section in which the ONU connected to the wireless communication system transmits a data signal or the like.

  In the section on the time axis to which the period A is assigned, the band is assigned to a REPORT signal or the like of another communication system. The ONU connected to the other communication system notifies the OLT of the data amount of the uplink data signal using the REPORT signal. In the section on the time axis to which the period A is assigned, the ONU connected to the other communication system acquires the GATE signal from the OLT. A section next to the section on the time axis to which the period A is assigned is a TDD transmission section. In the TDD transmission period, ONUs connected to other communication systems cannot transmit uplink data signals to the OLT.

  The section on the time axis to which the period B is assigned is a TDD untransmitted section. An ONU connected to another communication system transmits an uplink data signal in a section on the time axis to which period B is allocated (TDD non-transmission section) based on band allocation information included in the GATE signal. To do. That is, the ONU transmits the uplink data signal in the section on the time axis to which the period B is assigned even when the band is assigned to the data signal in the section on the time axis to which the period A is assigned. For this reason, the delay time becomes longer according to the length of the TDD transmission section. The OLT has a problem that it cannot improve the bandwidth utilization efficiency.

  FIG. 19 is a time chart showing a second example of traffic. The first row from the top shows the division of the structure of the TDD subframe. The second row from the top shows a section in which the OLT acquires a data signal or the like. The third row from the top shows a section in which an ONU connected to another communication system transmits a data signal or the like. The fourth row from the top shows a section in which the ONU connected to the wireless communication system transmits a data signal or the like.

  In FIG. 19, the DBA period is 0.5 milliseconds. The period of the TDD subframe in the communication system based on LTE is 1 millisecond. Therefore, the OLT performs dynamic bandwidth allocation twice for each TDD subframe. In FIG. 19, the section on the time axis to which the period B is assigned is the section next to the section on the time axis to which the period A is assigned. The ONU connected to another communication system transmits an uplink data signal in a section on the time axis to which the period B is assigned. Thus, the OLT can reduce the delay of the data signal when the DBA cycle is shorter than the time length of the TDD subframe. However, in FIG. 19, after estimating the TDD frame, at the first timing when the TDD subframe is switched from the upstream frame to the downstream frame, the bandwidth cannot be used for transmitting the data signal by using the bandwidth for transmitting the REPORT signal. The OLT (transmission device) has a problem in that it cannot improve the bandwidth utilization efficiency.

  In view of the above circumstances, the present invention provides a transmission system, a transmission method, and a transmission apparatus capable of improving band utilization efficiency in a transmission system that accommodates a communication system that communicates by time division duplex and another communication system. And to provide a transmission program.

  One aspect of the present invention is a transmission system that accommodates a communication system that communicates by time-division duplex and a different other communication system, and the communication among the bands that can be allocated to data signals of the communication system A band allocating unit for allocating a band to a data signal of the other communication system based on a first signal transmitted by the other communication system using a surplus band that is a band not allocated to a data signal of the system; An acquisition unit that acquires a data signal transmitted by the other communication system using a band allocated to a data signal of the system.

  One aspect of the present invention is the above transmission system, wherein the first signal transmitted from the other communication system using the surplus band is a data amount of a data signal buffered by the other communication system. It is a signal for notifying.

  One aspect of the present invention is the above transmission system, wherein the first signal transmitted by the other communication system using the surplus band is a part of a data signal buffered by the other communication system. It is.

  One aspect of the present invention is a transmission method in a transmission system that accommodates a communication system that communicates by time division duplex and different other communication systems, and has a bandwidth that can be allocated to a data signal of the communication system. A step of allocating a band to a data signal of the other communication system based on a first signal transmitted by the other communication system using a surplus band that is a band not allocated to the data signal of the communication system, Obtaining a data signal transmitted by the other communication system using a band assigned to the data signal of the communication system.

One aspect of the present invention is a transmission apparatus that accommodates a communication system that communicates by time-division duplex and different other communication systems, and the communication among the bands that can be allocated to data signals of the communication system A band allocating unit for allocating a band to a data signal of the other communication system based on a first signal transmitted by the other communication system using a surplus band that is a band not allocated to a data signal of the system; An acquisition unit for acquiring a data signal transmitted by the other communication system using a band allocated to a data signal of the system;
Is a transmission apparatus.

  According to one aspect of the present invention, the other communication system uses a surplus band that is a band that is not allocated to a data signal of the communication system, among bands that can be allocated to a data signal of the communication system. Based on the transmitted first signal, a procedure for assigning a band to the data signal of the other communication system and a data signal transmitted by the other communication system using the band assigned to the data signal of the other communication system are obtained. And a transmission program for executing the procedure.

  According to the present invention, it is possible to improve band utilization efficiency in a transmission system that accommodates a communication system that communicates by time division duplex and another communication system.

It is a figure which shows the example of a structure of the network system in embodiment. It is a figure which shows the 1st example of a structure of OLT in embodiment. It is a figure which shows the example of the data amount of the data signal of an uplink in embodiment. It is a time chart which shows the 1st example of traffic in an embodiment. It is a time chart which shows the 2nd example of traffic in an embodiment. It is a flowchart which shows the 1st example of operation | movement of OLT in embodiment. It is a figure which shows the 2nd example of a structure of OLT in embodiment. It is a flowchart which shows the 2nd example of operation | movement of OLT in embodiment. It is a time chart which shows the 3rd example of traffic in an embodiment. It is a flowchart which shows the 3rd example of operation | movement of OLT in embodiment. It is a figure which shows the example of a structure of the mobile fronthaul in a prior art. It is a figure which shows the TDD frame of LTE in a prior art. It is a figure which shows the example of the zone | band utilization of the radio area and optical area in a mobile fronthaul about the case where the radio base station of a TDD system in the prior art is accommodated. It is a figure which shows the example of the network system which used PON for the optical area. It is a figure which shows the example of a structure of OLT. It is a flowchart which shows the example of operation | movement of OLT. It is a figure which shows the example of the algorithm of dynamic bandwidth allocation (DBA). It is a time chart which shows the 1st example of traffic. It is a time chart which shows the 2nd example of traffic.

Embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating an example of the configuration of the network system 100. The network system 100 includes (transmission system), OLT 11 (transmission apparatus), optical splitter 12, ONUs 13-1 to 13-4 (Optical Network Unit), mobile radio terminals 21-1 to 21-2, and RRH 22-1. ~ 22-2 (wireless communication system), BBU23, mobile NW24 (mobile network), other communication system 31, other communication system 32, L2SW33 (layer 2 switch), other service NW34 (other service network) And an optical fiber 41 and optical fibers 42-1 to 52-4.

  Hereinafter, with respect to matters common to the ONUs 13-1 to 13-4, a part of the reference numerals are omitted and expressed as “ONU13”. Hereinafter, with respect to matters common to the mobile radio terminals 21-1 to 21-2, a part of the reference numerals are omitted and referred to as “mobile radio terminal 21”. Hereinafter, with respect to matters common to the RRHs 22-1 to 22-2, a part of the reference numerals are omitted and denoted as “RRH22”. Hereinafter, with respect to matters common to the optical fibers 42-1 to 52-4, a part of the reference numerals are omitted and denoted as “optical fiber 42”.

  The network system 100 may include more ONUs 13. The network system 100 may include more mobile radio terminals 21. The network system 100 may include more RRHs 22.

  Hereinafter, the direction from the OLT 11 toward the ONU 13 is referred to as “downward”. Hereinafter, the direction from the ONU 13 to the OLT 11 is referred to as “up”. In FIG. 1, the optical section is a section from the OLT 11 to the ONU 13. The optical section is, for example, a PON (Passive Optical network). The network topology of the network system 100 may be any configuration and is not limited to a specific topology. Hereinafter, a case where the network system 100 includes a PON will be described as an example.

  The OLT 11 is an optical subscriber line terminating device. The OLT 11 is a higher-level device than the ONU 13. The OLT 11 is managed by a communication carrier, for example. The OLT 11 accommodates the RRH 22 by relaying the data signal of the RRH 22. The OLT 11 relays the data signal of the RRH 22-1 to the BBU 23 via the ONU 13-1, the optical fiber 42-1, the optical splitter 12, and the optical fiber 41. The OLT 11 relays the data signal of the RRH 22-2 to the BBU 23 via the ONU 13-2, the optical fiber 42-2, the optical splitter 12, and the optical fiber 41.

  The OLT 11 accommodates the other communication system 31 by relaying the data signal of the other communication system 31. The OLT 11 relays the data signal of the other communication system 31 to the other service NW 34 via the ONU 13-3, the optical fiber 42-3, the optical splitter 12, and the optical fiber 41. The OLT 11 relays the data signal of the other communication system 32 to the other service NW 34 via the ONU 13-4, the optical fiber 42-4, the optical splitter 12, and the optical fiber 41.

  The OLT 11 defines TDD non-transmission sections in the uplink and downlink of the optical section. That is, the OLT 11 defines empty sections on the time axis of communication using the TDD scheme for the uplink and the downlink of the optical section. The OLT 11 transmits the data signal of the other communication system 31 in the TDD non-transmission section of the RRH 22. That is, the OLT 11 relays the uplink data signal acquired from the other communication system 31 in the uplink TDD non-transmission section of the optical section. The OLT 11 relays the downlink data signal to the other communication system 31 in the downlink TDD non-transmission section of the optical section.

  The OLT 11 transmits a data signal by a frequency division duplex (FDD) method. In the FDD scheme, different frequency bands are used for uplink and downlink. The OLT 11 transmits optical signals having different wavelengths on the uplink and the downlink by an optical wavelength division multiplexing (WDM) system. The WDM system is a kind of FDD system in optical transmission. In the WDM system, the first wavelength λ1 and the second wavelength λ2 of the optical signal are determined.

  The OLT 11 relays the downlink data signal of the mobile NW 24 to the ONU 13-1 using an optical signal having a predetermined first wavelength λ1. The OLT 11 relays the downlink data signal of the mobile NW 24 to the ONU 13-2 using the optical signal having the first wavelength λ1. The OLT 11 relays the downlink data signal of the other service NW 34 to the ONU 13-3 using the optical signal having the first wavelength λ1. The OLT 11 relays the downlink data signal of the other service NW 34 to the ONU 13-4 using the optical signal having the first wavelength λ1.

  The OLT 11 relays the uplink signal of the ONU 13-1 to the mobile NW 24 using an optical signal having a predetermined second wavelength λ2. The OLT 11 relays the uplink data signal of the ONU 13-2 to the mobile NW 24 using the optical signal having the second wavelength λ2. The OLT 11 relays the uplink data signal of the ONU 13-3 to the other service NW 34 using the optical signal of the second wavelength λ2. The OLT 11 relays the uplink data signal of the ONU 13-4 to the other service NW 34 using the optical signal having the second wavelength λ2. The OLT 11 may relay a data signal using an optical signal and a radio signal other than the optical signal.

  The optical splitter 12 distributes a TDM (time division multiplexing) optical signal transmitted via the optical fiber 41 to the ONUs 13-1 to 13-4. The optical splitter 12 multiplexes TDMA (time division multiple access) optical signals transmitted from the optical fiber 42. The optical splitter 12 transmits the combined optical signal to the OLT 11 via the optical fiber 41.

  The ONU 13 is a communication device. The ONU 13 is, for example, an optical subscriber line network device. The ONU 13 is installed in a subscriber's house, for example. When the ONU 13-1 is connected to the RRH 22-1, the ONU 13-1 relays communication between the optical splitter 12 and the RRH 22-1. When the ONU 13-2 is connected to the RRH 22-2, the ONU 13-2 relays communication between the optical splitter 12 and the RRH 22-2. When connected to the other communication system 31, the ONU 13-3 relays communication between the optical splitter 12 and the other communication system 31. When connected to the other communication system 32, the ONU 13-4 relays communication between the optical splitter 12 and the other communication system 32.

The mobile radio terminal 21 may communicate by the TDD method using a radio signal having a frequency f1 in a radio section with the RRH 22.
The RRH 22 performs uplink and downlink communication with the ONU 13 by the TDD scheme. In the TDD scheme, the same frequency band is used for uplink and downlink. In the TDD system, the data signals are orthogonal on the time axis. The RRH 22 may communicate by a TDD method using a radio signal having a frequency f1 in a radio section with the mobile radio terminal 21.

  Hereinafter, the ONU 13-1, the mobile radio terminal 21-1, and the RRH 22-1 are collectively referred to as a “radio communication system”. The wireless communication system may further include an ONU 13-2, a mobile wireless terminal 21-2, and an RRH 22-2.

  The BBU 23 is a signal processing unit of the radio base station. The BBU 23 transmits the data signal acquired from the L2SW 33 to the mobile NW 24. The BBU 23 transmits the data signal acquired from the mobile NW 24 to the L2SW 33.

  The mobile NW 24 is a mobile communication network. The mobile NW 24 is an upper network for the wireless communication system. The mobile NW 24 includes a communication device. The mobile NW 24 communicates with the BBU 23.

The other communication system 31 is a communication system that is more tolerant of requirements such as high speed and low delay than the RRH 22.
The other communication system 32 is a communication system different from the other communication system 31. The other communication system 32 is a communication system that is more tolerant of requirements such as high speed and low delay than the RRH 22. Hereinafter, items common to the other communication system 31 and the other communication system 32 are referred to as “other communication systems” by omitting symbols.

  The L2SW 33 transmits the data signal acquired from the BBU 23 or the other service NW 34 to the OLT 11. The L2SW 33 transmits the data signal acquired from the OLT 11 to the BBU 23 or the other service NW 34. For example, the L2SW 33 determines a relay destination based on a MAC (Media Access Control) address.

  The other service NW 34 includes another communication system host device that is a communication device. The other service NW 34 is an upper network with respect to another communication system. The other service NW 34 communicates with another communication system via the L2SW 33.

  FIG. 2 is a diagram illustrating an example of the configuration of the OLT 110a. The OLT 110a is the OLT 11 shown in FIG. The OLT 110a may be an external device connected to the OLT 11. The OLT 110a includes an L2SW 111, a traffic monitor 112, a time division duplex information estimation unit 113, a bandwidth allocation unit 114, and an interface 115. The OLT 110a may further include a memory. The memory is configured using a storage device having a nonvolatile memory (non-temporary recording medium) such as a magnetic hard disk device or a semiconductor storage device.

  Hereinafter, the L2SW 111, the traffic monitor 112, and the interface 115 are collectively referred to as a “relay unit”.

  A part of or all of the L2SW 111, the traffic monitor 112, the time division duplex information estimation unit 113, the bandwidth allocation unit 114, and the interface 115 is stored in a memory by a processor such as a CPU (Central Processing Unit), for example. It is a software function unit that functions by executing the programmed program. Also, some or all of these functional units may be hardware functional units (circuits) such as LSI (Large Scale Integration) and ASIC (Application Specific Integrated Circuit).

  The L2SW 112 transmits downlink data signals and control signals to the traffic monitor 112. The L2SW 112 may transmit an uplink data signal and a control signal to the BBU 23 or another communication system host apparatus 35 according to the destination.

  The traffic monitor 112 monitors uplink data signals. For example, the traffic monitor 112 monitors the data amount of the uplink data signal. The traffic monitor 112 may monitor downlink data signals. The traffic monitor 112 transmits the downlink data signal and control signal acquired from the L2SW 111 to the interface 115. The traffic monitor 112 transmits the uplink data signal and control signal acquired from the interface 115 to the L2SW 111.

  The time division duplex information estimation unit 113 acquires the result of monitoring the uplink data signal from the traffic monitor 112. The time division duplex information estimation unit 113 may acquire the result of monitoring the downlink data signal from the traffic monitor 112. Estimate the structure of the TDD subframe. The time division duplex information estimation unit of the time division duplex information estimation unit 122 estimates the timing of the TDD untransmitted interval based on the result of estimating the configuration of the TDD subframe.

  FIG. 3 is a diagram illustrating an example of a data amount of an uplink data signal. The horizontal axis indicates time. The vertical axis represents the data amount (estimated value) of the uplink data signal transmitted by the ONU 13 using the TDD scheme. The time division duplex information estimation unit 113 may estimate the timing of the TDD non-transmission section based on the data amount of the uplink data signal. The time division duplex information estimation unit 113 may estimate a section on the time axis where the data amount of the uplink data signal is less than the threshold as a TDD untransmitted section.

  The band allocating unit 114 determines the timing used for transmission of the uplink data signal based on the estimation result of the TDD non-transmission period. That is, the bandwidth allocation unit 114 determines the bandwidth allocation information based on the estimation result of the TDD non-transmission section. In the initial state, the bandwidth allocation unit 114 allocates a bandwidth to the uplink data signal of the wireless communication system by FBA. In the initial state, the band allocation unit 114 stops transmission of data signals of other communication systems.

  In a normal state, the band allocation unit 114 allocates a band to the uplink data signal of the wireless communication system by FBA for the TDD transmission section. The normal state is a state in which no periodic congestion occurs in the traffic, for example. In a normal state, the band allocation unit 114 allocates a band to a data signal of another communication system by FBA or dynamic band allocation (DBA) for a TDD untransmitted section.

  The interface 115 acquires band allocation information from the band allocation unit 114. The interface 115 converts the downlink data signal and control signal acquired from the L2SW 111 into a frame used in the PON. For example, the interface 115 may generate a GATE frame including band allocation information.

  The interface 115 converts the downlink data signal (electrical signal) converted into the frame into an optical signal having the wavelength λ1. The interface 115 (transmission unit) transmits the optical signal having the first wavelength λ1 to the optical fiber 41 via the optical coupler. The optical signal is transmitted to the ONU 13 through the optical fiber 41 and the optical fiber 42.

  The interface 115 (acquisition unit) acquires the optical signal having the second wavelength λ <b> 2 from the ONU 13 through the optical fiber 42 and the optical fiber 41. The interface 115 converts the received optical signal into an electrical signal. The interface 115 transmits the converted uplink data signal and control signal to the traffic monitor 112.

  FIG. 4 is a time chart showing a first example of traffic. The horizontal axis indicates time. The first row from the top shows the division of the structure of the TDD subframe. The second row from the top shows a section in which the OLT acquires a data signal or the like. The third row from the top shows a section in which ONUs 13-3 and 13-4 connected to other communication systems transmit data signals and the like. The fourth row from the top shows a section in which the ONUs 13-1 and 13-2 connected to the wireless communication system transmit data signals and the like.

  In FIG. 4, the DBA period is 1 millisecond. The period of the TDD subframe in the wireless communication system based on LTE is 1 millisecond. That is, in FIG. 4, the DBA cycle and the time length of the TDD subframe are the same. A part of the TDD transmission section to which the period A is assigned is a transmission stop section of the ONUs 13-3 and 13-4. That is, in the TDD transmission period, the ONUs 13-3 and 13-4 stop transmitting uplink data signals.

  Hereinafter, of the bands that can be allocated to the data signal, the band that is not allocated to the data signal is referred to as “surplus band”. For example, in the network system 100 having a transmission rate of 10 Gbps, when the OLT 110a accommodates RRHs 22-1 and 22-2 each having a transmission rate of 3 Gbps, the total value of the transmission rates of the wireless communication system is 6 (= 3 + 3). Gbps. 4 (= 10−6) Gbps, which is the difference between the transmission rate 10 Gbps of the network system 100 and the total transmission rate 6 Gbps of the wireless communication system, is a surplus bandwidth of the uplink data signal of the wireless communication system.

  The band allocation unit 114 allocates the REPORT signal to the surplus band. In FIG. 4, a part of the TDD transmission section to which the period A is allocated is a signal transmission section (excess period) allocated to the surplus band. When the TDD subframe is allocated to the uplink, the ONUs 13-3 and 13-4 transmit a REPORT signal (control signal) in the signal transmission section allocated to the surplus band. The process of allocating the band is completed in the signal transmission period (TDD transmission period to which the period A is allocated) of each wireless communication system.

  When the TDD subframe is allocated to the downlink, the ONUs 13-3 and 13-4 transmit the REPORT signal in the signal transmission period of the other communication system (the TDD non-transmission period to which the period B is allocated). The ONUs 13-3 and 13-4 transmit uplink data signals in the signal transmission section of another communication system. Thus, the OLT 110a can reduce transmission delay. The OLT 110a can improve the bandwidth utilization efficiency.

  The ONUs 13-3 and 13-4 transmit the REPORT signal even in the TDD non-transmission section to which the period B is assigned. When the next section is a TDD non-transmission section, the band allocation unit 114 performs dynamic band allocation of the band of the next section based on the REPORT signal. If the next section is a TDD transmission section, the bandwidth allocation unit 114 discards the REPORT signal. The REPORT signal acquired by the bandwidth allocation unit 114 next time includes the data amount of the uplink data signal notified using the discarded REPORT signal and the uplink buffered by the ONUONU 13-3 or 13-4. Data amount of the data signal. Therefore, even if the bandwidth allocation unit 114 discards the REPORT signal, no loss of the uplink data signal occurs.

  FIG. 5 is a time chart showing a second example of traffic. The horizontal axis indicates time. The first row from the top shows the division of the structure of the TDD subframe. The second row from the top shows a section in which the OLT acquires a data signal or the like. The third row from the top shows a section in which ONUs 13-3 and 13-4 connected to other communication systems transmit data signals and the like. The fourth row from the top shows a section in which the ONUs 13-1 and 13-2 connected to the wireless communication system transmit data signals and the like.

  In FIG. 5, the DBA period is 0.5 milliseconds. The period of the TDD subframe in the wireless communication system based on LTE is 1 millisecond. That is, in FIG. 5, the DBA cycle is half the time length of the TDD subframe. A part of the TDD transmission section is a transmission stop section of the ONUs 13-3 and 13-4. That is, in the TDD transmission period, the ONUs 13-3 and 13-4 stop transmitting uplink data signals.

  When the TDD subframe is allocated to the uplink, the ONUs 13-3 and 13-4 transmit the REPORT signal and acquire the GATE signal from the OLT 110a in the signal transmission section allocated to the surplus band.

  When the TDD subframe is allocated to the downlink, the ONUs 13-3 and 13-4 transmit the REPORT signal twice in the signal transmission period of the other communication system (the TDD non-transmission period to which the period B is allocated). The GATE signal is acquired for each frame from the OLT 110a. The ONUs 13-3 and 13-4 use the GATE signal acquired when the TDD subframe is allocated to the uplink and the GATE signal acquired for each frame when the TDD subframe is allocated to the downlink. The transmission permission in all DBA periods in the signal transmission section of the other communication system is acquired. The ONUs 13-3 and 13-4 can transmit an uplink data signal by acquiring a GATE signal. Since the OLT 110a can transmit an uplink data signal in all DBA periods of a signal transmission section of another communication system even immediately after estimation of a TDD frame, it is possible to improve band utilization efficiency.

  FIG. 6 is a flowchart illustrating a first example of the operation of the OLT. The bandwidth allocation unit 114 acquires a REPORT signal or an uplink data signal (step S101). The bandwidth allocation unit 114 determines whether or not the next section is a TDD transmission section (step S102).

  When the next section is a TDD transmission section (step S102: YES), the band allocation unit 114 discards the REPORT signal (step S103).

  The band allocating unit 114 allocates a band to the uplink signal of the wireless communication system by the FBA using the GATE signal, but does not instruct the wireless communication system to transmit the REPORT signal. The band allocating unit 114 does not allocate a band to an uplink signal of another communication system, but instructs the other communication system to transmit a REPORT signal using a GATE signal. The band allocation unit 114 transmits the GATE signal to the wireless communication system and the other communication system via the interface 115 (step S104).

  When the next section is a TDD non-transmission section (step S102: NO), the band allocation unit 114 allocates a band to the uplink data signal based on the REPORT signal (step S105).

  The band allocation unit 114 does not allocate a band to the uplink signal of the wireless communication system, and does not instruct the wireless communication system to transmit the REPORT signal. The band allocation unit 114 allocates a band to the uplink signal of the other communication system by the DBA by the GATE signal, and instructs the other communication system to transmit the REPORT signal by the GATE signal. The band allocation unit 114 transmits a GATE signal to another communication system via the interface 115 (step S106).

  As described above, in the network system 100 (transmission system) according to the first embodiment, the band allocation unit 114 performs data transmission in the other communication system based on the first signal transmitted from the other communication system using the surplus band. Allocate bandwidth to the signal. The interface 115 acquires the data signal transmitted by the other communication system using the band assigned to the data signal of the other communication system. The first signal of the first embodiment is a signal for notifying the data amount of a data signal buffered by another communication system, that is, a REPORT signal (transmission request signal).

  As a result, the network system 100 according to the first embodiment can improve bandwidth utilization efficiency in the network system 100 that accommodates a communication system that communicates by time division duplex and another communication system.

  The ONUs 13-3 and 13-4 of the first embodiment can transmit an uplink data signal with a short delay time in a TDD non-transmission period. The ONUs 13-3 and 13-4 of the first embodiment can efficiently transmit uplink data signals in the TDD non-transmission section.

(Second Embodiment)
The second embodiment is different from the first embodiment in that a part of the uplink data signal is allocated to the surplus band. In the second embodiment, only differences from the first embodiment will be described.

  FIG. 7 is a diagram illustrating a second example of the configuration of the OLT 110b. The OLT 110b is the OLT 11 shown in FIG. The OLT 110b may be an external device connected to the OLT 11. The OLT 110b includes an L2SW 111, a traffic monitor 112, a time division duplex information estimation unit 113, a bandwidth allocation unit 114, an interface 115, and a report amount estimation unit 116. The OLT 110b may further include a memory. The memory is configured using a storage device having a nonvolatile memory (non-temporary recording medium) such as a magnetic hard disk device or a semiconductor storage device.

  The band allocating unit 114 allocates a surplus band to an uplink data signal band of another communication system. For example, when the surplus bandwidth is 1 Gbps, the bandwidth allocation unit 114 allocates each 500 Mbps bandwidth to the uplink data signal of the ONU 13-3 and the uplink data signal of the ONU 13-4 by FBA. Within this surplus band, the ONU 13 transmits a data signal having a predetermined data amount of Y [%] that is a part of the data amount X bytes that the ONU 13 should originally transmit. The amount of data that should be transmitted is the amount of data that the ONU 13 normally requests permission for transmission using the REPORT signal.

  The remaining data amount (report amount) (= X × (100−Y) / 100) to be acquired in the TDD non-transmission section by the OLT 110b uses the surplus bandwidth because the value of Y [%] is predetermined. Thus, it can be estimated by proportional calculation (Y: (100−Y)) based on the data amount (= X × Y / 100) transmitted by the ONU 13. This eliminates the need for the ONU 13 to transmit a REPORT signal (transmission request signal) using the surplus bandwidth. Also, since the ONU 13 can transmit a part of the data signal using the surplus band, it becomes possible to transmit the uplink data signal more efficiently than in the first embodiment. .

  In FIG. 7, the ONU 13 has a data amount of X bytes Y [%] (= X × (Y / 100)) in a section on the time axis to which the surplus bandwidth is allocated (part of the TDD transmission section). A signal is transmitted to the OLT 110b.

  The interface 115 acquires a part of the uplink data signal (Y [%] data amount) buffered by the ONU 13 from the ONU 13 in the section on the time axis allocated to the surplus bandwidth. The report amount estimation unit 116 acquires a part of the uplink data signal from the interface 115 in the section on the time axis assigned to the surplus band.

  The report amount estimation unit 116 (estimation unit) estimates the remaining data amount (report amount) that the OLT 110b should acquire in the TDD non-transmission section based on a part of the uplink data signal. That is, the report amount estimation unit 116 estimates a data amount of (100−Y) [%] (= X × (100−Y) / 100) of X bytes. The report amount estimation unit 116 transmits the estimation result of the remaining data amount that the OLT 110b should acquire in the TDD non-transmission section to the band allocation unit 114. The band allocation unit 114 transmits a GATE signal including band allocation information based on the estimation result to the ONU 13 via the interface 115.

  When the ONU 13-1 acquires the GATE signal, the ONU 13-1 transmits a data signal having a data amount of (100-Y) [%] of X bytes to the OLT 110b in the TDD transmission section. The same applies to the ONU 13-2. The GATE signal may include information for notifying that it is a TDD transmission period. When the ONU 13-3 acquires the GATE signal, the ONU 13-3 transmits a data signal having a data amount of (100−Y) [%] of X bytes to the OLT 110 b in the TDD non-transmission section. The same applies to the ONU 13-4.

  FIG. 8 is a flowchart illustrating a second example of the operation of the OLT. The band allocation unit 114 acquires a REPORT signal, an uplink data signal, or a part of the uplink data signal (step S201). The bandwidth allocation unit 114 determines whether or not the next section is a TDD transmission section (step S202).

  When the next section is a TDD transmission section (step S202: YES), the bandwidth allocation unit 114 discards the REPORT signal (step S203).

  The band allocating unit 114 allocates a band to the uplink signal of the wireless communication system by the FBA using the GATE signal, but does not instruct the wireless communication system to transmit the REPORT signal. The band allocating unit 114 allocates a band to a part of the uplink signal of the other communication system by the DBA by the GATE signal, but does not instruct the other communication system to transmit the REPORT signal. The bandwidth allocating unit 114 transmits a GATE signal to the wireless communication system and other communication systems via the interface 115 (step S204).

  When the next section is a TDD non-transmission section (step S202: NO), the band allocation unit 114 allocates a band to the uplink data signal based on the REPORT signal. The band allocating unit 114 may allocate a band to the uplink data signal based on a part of the uplink data signal. For example, the band allocating unit 114 may allocate a band to the uplink data signal based on a partial data amount of the uplink data signal (step S205).

  The band allocation unit 114 does not allocate a band to the uplink signal of the wireless communication system, and does not instruct the wireless communication system to transmit the REPORT signal. The band allocation unit 114 allocates a band to the uplink signal of the other communication system by the DBA by the GATE signal, and instructs the other communication system to transmit the REPORT signal by the GATE signal. The band allocation unit 114 transmits the GATE signal to another communication system via the interface 115 (step S206).

  As described above, in the network system 100 (transmission system) according to the second embodiment, the band allocation unit 114 performs data transmission in the other communication system based on the first signal transmitted from the other communication system using the surplus band. Allocate bandwidth to the signal. The interface 115 acquires the data signal transmitted by the other communication system using the band assigned to the data signal of the other communication system. The first signal of the second embodiment is a part of the data signal buffered by another communication system.

  As a result, the network system 100 of the second embodiment can improve bandwidth utilization efficiency in the network system 100 that accommodates a communication system that communicates by time division duplex and another communication system.

(Third embodiment)
In the third embodiment, in the section where the TDD subframe is allocated to the downlink (TDD non-transmission section), the time required for transmitting all the data signals buffered by the ONU 13 is the TDD subframe. Even if it is longer than the time length of the frame, the point that the REPORT signal is not transmitted until the ONU 13 transmits all the data signals is different from the first embodiment. In the third embodiment, only differences from the first embodiment will be described.

  The ONU 13 transmits a REPORT signal in the signal transmission section assigned to the surplus band. The ONU 13 does not transmit a REPORT signal in the TDD non-transmission section.

  FIG. 9 is a time chart showing a third example of traffic. The horizontal axis indicates time. The first row from the top shows the division of the structure of the TDD subframe. The second row from the top shows a section in which the OLT acquires a data signal or the like. The third row from the top shows a section in which ONUs 13-3 and 13-4 connected to other communication systems transmit data signals and the like. The fourth row from the top shows a section in which the ONUs 13-1 and 13-2 connected to the wireless communication system transmit data signals and the like.

  In FIG. 9, the DBA period in the TDD transmission section is 0.5 milliseconds. That is, in FIG. 9, the DBA period in the TDD transmission period is shorter than the time length of the TDD subframe. The operations of the OLT 110a and the ONU 13 shown in FIG. 9 and the operations of the OLT 110a and the ONU 13 shown in FIG. 5 are the same for the TDD transmission interval. The ONUs 13-3 and 13-4 prioritize the uplink data signal over the REPORT signal and transmit the uplink data signal to the OLT 110a in the TDD non-transmission period.

  FIG. 10 is a flowchart illustrating a third example of the OLT operation. The bandwidth allocating unit 114 acquires a REPORT signal or an uplink data signal (step S301). The bandwidth allocation unit 114 determines whether or not the next section is a TDD transmission section (step S302).

  When the next section is a TDD transmission section (step S302: YES), the bandwidth allocation unit 114 discards the REPORT signal (step S303).

  The band allocating unit 114 allocates a band to the uplink signal of the wireless communication system by the FBA using the GATE signal, but does not instruct the wireless communication system to transmit the REPORT signal. The band allocating unit 114 does not allocate a band to an uplink signal of another communication system, but instructs the other communication system to transmit a REPORT signal using a GATE signal. The bandwidth allocation unit 114 transmits the GATE signal to the wireless communication system and other communication systems via the interface 115 (step S304).

  When the next section is a TDD non-transmission section (step S302: NO), the bandwidth allocation unit 114 determines whether a REPORT signal has been acquired (step S305). When the REPORT signal is acquired (step S305: YES), the band allocation unit 114 allocates a band to the uplink data signal based on the REPORT signal (step S306).

  The band allocation unit 114 does not allocate a band to the uplink signal of the wireless communication system, and does not instruct the wireless communication system to transmit the REPORT signal. The band allocation unit 114 allocates a band to the uplink signal of the other communication system by the DBA by the GATE signal, but does not instruct the other communication system to transmit the REPORT signal. The bandwidth allocation unit 114 transmits the GATE signal to the other communication system via the interface 115 (step S307).

  When the REPORT signal has not been acquired (step S305: NO), the bandwidth allocation unit 114 determines whether or not all uplink data signals have been acquired (step S308). When all the uplink data signals have been acquired (step S308: YES), the band allocation unit 114 does not allocate a band to the uplink signal of the wireless communication system and does not instruct the wireless communication system to transmit the REPORT signal. . The band allocation unit 114 allocates a band to the uplink signal of the other communication system by the DBA by the GATE signal, and instructs the other communication system to transmit the REPORT signal by the GATE signal. The bandwidth allocation unit 114 transmits the GATE signal to the other communication system via the interface 115 (step S309).

  When an unacquired uplink data signal remains (step S308: NO), the band allocating unit 114 does not allocate a band to the uplink signal of the wireless communication system and transmits a REPORT signal to the wireless communication system. Do not instruct. The band allocating unit 114 allocates a band to an uplink signal of another communication system by DBA using a GATE signal. The band allocation unit 114 transmits a GATE signal to another communication system via the interface 115 (step S310).

  As described above, the network system 100 (transmission system) according to the third embodiment acquires the REPORT signal from the ONUs 13-3 and 13-4 in the TDD transmission section. The network system 100 according to the third embodiment causes only the uplink data signal to be transmitted to the ONUs 13-3 and 13-4 in the next TDD non-transmission section.

  As a result, the network system 100 of the third embodiment can further improve the band utilization efficiency in the network system 100 that accommodates a communication system that communicates by time division duplex and another communication system. The first to third embodiments may be combined.

  You may make it implement | achieve at least one part of the transmission system and transmission apparatus in embodiment mentioned above with a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be a program for realizing a part of the above-described functions, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system. You may implement | achieve using programmable logic devices, such as FPGA (Field Programmable Gate Array).

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

DESCRIPTION OF SYMBOLS 11 ... OLT, 12 ... Optical splitter, 13 ... ONU, 21 ... Mobile radio | wireless terminal, 22 ... RRH, 23 ... BBU, 24 ... Mobile NW, 31 ... Other communication systems, 32 ... Other communication systems, 33 ... L2SW (Layer 2 34) Other service NW, 35 ... Other communication system host device, 41 ... Optical fiber, 42 ... Optical fiber, 100 ... Network system, 110a ... OLT, 110b ... OLT, 111 ... L2SW, 112 ... Traffic monitor unit, 113: Time division duplex information estimation unit, 114 ... Band allocation unit, 115 ... Interface, 116 ... Report amount estimation unit

Claims (6)

A transmission system that accommodates a communication system that communicates by time division duplex and a different other communication system,
Based on the first signal transmitted by the other communication system using a surplus band that is a band that is not allocated to the data signal of the communication system among bands that can be allocated to the data signal of the communication system, A bandwidth allocation unit that allocates a bandwidth to a data signal of another communication system;
An acquisition unit for acquiring a data signal transmitted by the other communication system using a band allocated to the data signal of the other communication system;
A transmission system comprising:   The first signal transmitted from the other communication system using the surplus band is a signal for notifying a data amount of a data signal buffered by the other communication system. Transmission system.   The transmission system according to claim 1, wherein the first signal transmitted from the other communication system using the surplus band is a part of a data signal buffered by the other communication system. A transmission method in a transmission system accommodating a communication system communicating by time division duplex and a different other communication system,
Based on the first signal transmitted by the other communication system using a surplus band that is a band that is not allocated to the data signal of the communication system among bands that can be allocated to the data signal of the communication system, Allocating a band to a data signal of another communication system;
Obtaining a data signal transmitted by the other communication system using a band allocated to the data signal of the other communication system;
Including transmission method. A communication apparatus that accommodates a communication system that communicates by time division duplex and a different other communication system,
Based on the first signal transmitted by the other communication system using a surplus band that is a band that is not allocated to the data signal of the communication system among bands that can be allocated to the data signal of the communication system, A bandwidth allocation unit that allocates a bandwidth to a data signal of another communication system;
An acquisition unit for acquiring a data signal transmitted by the other communication system using a band allocated to the data signal of the other communication system;
A transmission apparatus comprising: On the computer,
A first transmitted by a different communication system using a surplus band that is a band that cannot be allocated to a data signal of the communication system among bands that can be allocated to a data signal of a communication system communicating by time division duplex . Allocating a band to a data signal of the other communication system based on a signal;
Obtaining a data signal transmitted by the other communication system using a band allocated to the data signal of the other communication system;
A transmission program for executing

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