JP6636896B2 - Bandwidth allocation device - Google Patents

Description

  The present invention relates to a band allocation device.

  There is a radio communication system in which an antenna unit (RRH: Remote Radio Head) of a radio base station and a signal processing unit (BBU: Baseband Unit) are separated. In this wireless communication system, the RRH and the BBU are connected via an optical device and an optical fiber, and this optical section is called a mobile fronthaul (MFH). FIG. 9 is a diagram illustrating a configuration example of the MFH.

  In recent years, in order to reduce the cost of the MFH, studies have been made to accommodate the RRH using a TDM-PON (Time Division Multiplexing-Passive Optical Network) system (for example, see Non-Patent Document 1). See Patent Document 2). In the TDM-PON system, a TDMA (Time Division Multiple Access) method is used for transmitting a signal from an optical terminal unit (ONU: Optical Network Unit) to an optical terminal unit (OLT: Optical Line Terminal). Therefore, when the RRH is accommodated using the TDM-PON, the traffic transferred to the MFH is estimated based on the traffic information between the RRH and the wireless terminal, and the bandwidth allocated from the optical terminal device to the optical terminal device is adjusted. There has been proposed a method of changing the frequency (for example, see Non-Patent Document 2).

  FIG. 10 is a diagram illustrating a configuration of a conventional terminal device. In a conventional terminal device such as an OLT, an upstream signal or a downstream signal in communication with a terminal device such as an ONU is acquired by a traffic information acquisition unit. The traffic information acquiring unit transfers the acquired traffic information to the traffic amount estimating unit, and the traffic amount estimating unit estimates a traffic pattern based on traffic information for several hours to several days. In late nights and early mornings, the traffic volume is smaller than during the day, because the wireless terminals are used less frequently. During the day, the wireless terminal is frequently used, so that the traffic volume also increases. A pattern representing such an increase or decrease in traffic volume is defined as a traffic pattern. The estimated traffic pattern is transferred to the band allocation function unit.

FIG. 11 is a diagram illustrating a band allocation method by the band allocation function unit according to the related art. The terminal device transmits the bandwidth allocation amount and the transmission permission time of the uplink signal to the terminal device in a DBA (Dynamic Bandwidth Allocation) cycle. Until time t ₂ is the traffic collection period for the estimation of traffic patterns, bandwidth allocator allocates a traffic R _{p [bps} (bits per second) of the stationary at each DBA cycle termination device. Terminal equipment starts a variable bandwidth allocation in a time t ₂ after the traffic collection period ends. The bandwidth allocation function unit determines the bandwidth allocation based on the average traffic during the traffic collection period. For example, the bandwidth allocation amount in the period _{T 1} is _R 1 [bps]. Bandwidth allocator is in each DBA period in the period T _1, fixedly assigning the bandwidth allocation amount R ₁ to terminator. For example, when the period T ₁ = 6.0 hours, the DBA cycle is 250 μs (microseconds), and the bandwidth allocation amount R ₁ = 1.0 Gbps, the terminal device sets the terminal device to a 1.0 Gbps bandwidth every 250 μs. Continue to assign for 6.0 hours.

"NTT Technical Journal, Basic Technology Course [GE-PON Technology], What is the 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> T. Kobayashi, H. Ou, D. Hisano, T. Shimada, J. Terada and A. Otaka, “Bandwidth Allocation scheme based on Simple Statistical Traffic Analysis for TDM-PON based Mobile Fronthaul”, in Proc. Of OFC2016, paper W3C.7, March 2016

In the conventional bandwidth allocation method, as shown in FIG. 11, a bandwidth allocation amount is calculated for each time slot based on statistical information such as an average traffic amount, and the bandwidth allocation amount is made variable. For example, fixed bandwidth allocation amount R ₁ in the time slot period T ₁ of the 11 fixedly assigned to the terminating device, when switching to the time slot period T ₂ are, the bandwidth allocation amount R ₂ to termination equipment Assign to

However, there is a problem when the traffic model in the wireless base station is a burst signal. FIG. 12 is a diagram illustrating an example of a traffic model in which a burst signal is generated. When an uplink signal is transmitted from a wireless terminal to the RRH, the RRH buffers the uplink signal for one TTI (Transmission Time Interval). TTI represents the minimum unit of wireless scheduling. The time length of the TTI is equal to one subframe length, which is a frame divided for uplink and downlink transmission in a radio frame. In the case of LTE (Long Term Evolution), the period of wireless scheduling is 1 ms, so 1 TTI is 1 ms. In the fifth generation mobile communication system (5G), which will be mobile access in the future, reduction of TTI is being studied. The RRH performs demodulation and decoding operations on the buffered uplink signal after a lapse of 1 TTI. The demodulated and decoded uplink signal is sequentially buffered from the beginning of the TTI, and is transferred from the RRH to the terminal device. Therefore, as shown in the traffic flowing through the MFH in FIG. 13, the terminal device receives the burst signal from the RRH at the TTI cycle via the terminating device. Therefore, regardless of the traffic volume of the period _T 1 through T ₃ in FIG. 11, the data traffic arising from the beginning of the TTI period.

In the case of the radio base station having the traffic model shown in FIGS. 12 and 13, the increase or decrease in the traffic amount indicated by the traffic pattern in FIG. 11 becomes the burst signal length for each TTI cycle as shown in FIG. For traffic in the period T ₁ is small, the length of the burst signal in 1TTI is short compared to the period T _2. In most traffic volume is large period T _2, the length of the burst signal in 1TTI is the longest. Actually, data traffic occurring in one TTI is encapsulated in a frame such as Ethernet (registered trademark), so that the traffic amount can be expressed by the number of Ethernet (registered trademark) frames in one TTI.

  FIG. 15 is a diagram illustrating a result of applying a conventional bandwidth allocation method based on statistical information such as an average traffic amount. Since the bandwidth allocation is determined based on the traffic averaged over a period spanning a plurality of TTIs, it may not be possible to transmit all the traffic in the DBA cycle that coincides with the beginning of the TTI cycle. The transmission target signal is buffered in the terminal device. Since the signal buffered in the terminating device is transmitted in the next and subsequent DBA periods, the signal is accumulated as a delay by the DBA period required for transmission.

  In view of the above circumstances, the present invention provides a band allocating device that can allocate a band to a terminal device so as to reduce delay in relaying when a terminal device relays a signal received from a lower device to a terminal device. It is intended to be.

One aspect of the present invention is that, for each lower-level device connected to a terminating device, a traffic information acquisition unit that acquires traffic information indicating a time-series traffic amount of communication performed by the lower-level device via the terminating device; A traffic amount estimating unit that extracts a fluctuation period of the traffic based on the traffic information, and divides the extracted fluctuation period into one or more time slots; a traffic transmission period based on the traffic information; A traffic transmission cycle estimating unit for estimating the start timing of a cycle, and the traffic information, based on the traffic transmission cycle and the start timing, in each of the time slots, of the lower-level device obtained from the traffic information. The bandwidth required for transmitting the estimated traffic volume is determined by the As allocated during the period from the timing to the timing earlier than the start timing of the next of said traffic transmission period, the bandwidth allocated to the terminating device in the traffic transmission period contained in the time slot is connected to the lower device A bandwidth allocating device comprising: a bandwidth quota calculating unit that changes according to time; and a band allocating function unit that allocates a bandwidth to the terminal device according to a control schedule based on a band allocated by the bandwidth quota calculating unit.

  One aspect of the present invention is the above-mentioned band allocation device, wherein the traffic amount estimating unit acquires, for each time slot, an average value and a variance value of the traffic amount of the lower order device based on the traffic information. The bandwidth allocation amount calculating unit, in the traffic transmission cycle, switches a timing of switching a bandwidth to be allocated to the terminating device connected to the lower-level device, the traffic of the lower-level device in the time slot including the traffic transmission period. It is calculated based on the average value and the variance value of the amount and the risk rate.

  One aspect of the present invention is the above-described band allocation device, wherein the band allocation amount calculation unit is configured to transmit, in the traffic transmission cycle, a band necessary for transmitting an estimated traffic amount of the lower-level device obtained from the traffic information. Is assigned to a time period from the start timing of the traffic transmission cycle to a timing before the start timing of the next traffic transmission cycle, and then a surplus bandwidth for transmitting traffic exceeding the estimated traffic is allocated. Assign to the next time zone.

  One aspect of the present invention is the above-mentioned band allocating apparatus, wherein the band allocating function unit, when traffic of the lower-level device occurs beyond a predetermined timing in a time zone to which the surplus band is allocated, A fixed bandwidth that does not change with time is allocated to the terminating device connected to the lower-level device, and the bandwidth quota calculation unit calculates the traffic information acquired by the traffic information acquisition unit when the fixed bandwidth is allocated. Based on the above, a time band is switched in the traffic transmission cycle to newly calculate a band to be allocated to the terminating device.

  One embodiment of the present invention is the above-mentioned band allocating apparatus, wherein the band allocating function unit determines whether the number of times traffic of the lower-level apparatus has occurred beyond a predetermined timing in a time zone to which the surplus band is allocated is a threshold. In this case, a fixed band that does not change with time is allocated to the terminal device connected to the lower-level device.

  According to the present invention, when a terminal device relays a signal received from a lower-level device to a terminal device, it becomes possible to allocate a band to the terminal device so as to reduce delay in the relay.

FIG. 1 is a diagram illustrating a configuration of an access network system according to a first embodiment of the present embodiment. FIG. 3 is a functional block diagram illustrating a configuration of the terminal device according to the embodiment. It is a flowchart which shows the band allocation process in the terminal station by the embodiment. FIG. 3 is a diagram showing a bandwidth allocation method according to the embodiment. It is a functional block diagram showing the composition of the terminal unit by a 2nd embodiment. It is a flowchart which shows the band allocation process in the terminal station by the embodiment. FIG. 3 is a diagram showing a bandwidth allocation method according to the embodiment. 13 is a flowchart illustrating a bandwidth allocation process in the terminal device according to the third embodiment. FIG. 11 is a diagram illustrating a configuration example of a conventional MFH. FIG. 3 is a diagram illustrating a configuration of a terminal device according to the related art. FIG. 11 is a diagram illustrating a band allocation method by a band allocation function unit according to the related art. FIG. 3 is a diagram illustrating an example of a traffic model in which a burst signal is generated. It is a figure showing an example of the traffic which flows through MFH. FIG. 3 is a diagram illustrating a relationship between a traffic amount and a packet length. FIG. 13 is a diagram illustrating a result of applying the bandwidth allocation according to the related art.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The bandwidth allocating apparatus according to the present embodiment changes the bandwidth allocation within one TTI (Transmission Time Interval) cycle to be allocated to the terminating apparatus in DBA (Dynamic Bandwidth Allocation) cycle units based on the traffic estimation result. In other words, the bandwidth allocating apparatus according to the present embodiment fixedly allocates the bandwidth to the terminating device in the DBA cycle that matches the beginning of the 1TTI cycle, and transfers the signal without delay. The DBA period is a period in which the terminal station device transmits the bandwidth allocation amount and the transmission permission time of the uplink signal to the terminal device. When the traffic is smaller than the traffic at the peak, there is an area where no signal is generated at the tail in one TTI cycle. The bandwidth allocating apparatus of the present embodiment can compress the bandwidth used by the mobile system by making the allocated bandwidth variable in the DBA cycle corresponding to this area. The surplus band generated by this band allocation operation can be used as a period for accommodating another system, putting a terminal device connected to the mobile base station to sleep, or accepting a new connection terminal device, for example.

[First Embodiment]
In the present embodiment, a basic configuration of a band allocation device will be described.
FIG. 1 is a diagram showing a configuration of the access network system 8 of the present embodiment. The access network system 8 has a configuration in which a relay transmission system including the terminal station device 1, the terminal device 2, and the optical splitter 3 accommodates a communication system including the upper device 5 and the lower device 6. To accommodate a communication system means to relay communication in the communication system.

  The relay transmission system is, for example, an optical relay transmission system such as a PON (Passive Optical Network) system. When the relay transmission system is a PON system, the terminal device 1 is an optical terminal device (OLT: Optical Line Terminal), and the terminal device 2 is an optical terminal device (ONU: Optical Network Unit). The direction from the terminal device 1 to the terminal device 2 is downward, and the direction from the terminal device 2 to the terminal device 1 is upward. The optical splitter 3 distributes a TDM (time division multiplex) optical signal transmitted from the terminal device 1 through one optical fiber 41 to the optical fibers 42 connected to each of the plurality of terminating devices 2. The optical splitter 3 multiplexes a TDMA (time division multiple access) optical signal transmitted from the optical fiber 42 connected to each of the plurality of terminating devices 2 and outputs the multiplexed optical signal to the optical fiber 41. The terminal device 1 has a function as a band allocating device that allocates a band to each terminal device 2.

  The communication system is, for example, a mobile network. When the communication system is a mobile network, the upper device 5 is a BBU (Baseband Unit), and the lower device 6 is an RRH (Remote Radio Head). The RRH wirelessly communicates with the mobile radio terminal by the TDD scheme. The relay transmission system can accommodate a plurality of communication systems.

  FIG. 2 is a functional block diagram showing the configuration of the terminal device 1, in which only functional blocks related to the present embodiment are extracted and shown. The terminal device 1 includes an upper transmission / reception function unit 11, a lower transmission / reception function unit 12, a traffic information acquisition unit 14, a traffic volume estimation unit 15, a traffic transmission cycle / timing extraction unit 16, a bandwidth allocation calculation unit 17, and a bandwidth allocation function unit. 18 is provided.

  The upper transmission / reception function unit 11 is an interface responsible for transmitting and receiving data to and from the upper device 5. The upper transmission / reception function unit 11 outputs a downstream signal addressed to the lower device 6 received from the upper device 5 to the lower transmission / reception function unit 12. Also, the upper transmission / reception function unit 11 transmits an upstream signal from the lower device 6 to the upper device 5 received from the lower transmission / reception function unit 12 to the upper device 5.

  The lower transmission / reception function unit 12 is an interface for transmitting / receiving data to / from the terminating device 2. The lower transmission / reception function unit 12 converts a downstream signal output from the upper transmission / reception function unit 11 or a control signal output from the band allocation function unit 18 from an electric signal to an optical signal and outputs the signal to the terminating device 2. The lower transmission / reception function unit 12 converts an upstream signal received from the terminating device 2 from an optical signal to an electric signal, and outputs an upstream signal addressed from the lower device 6 to the higher device 5 to the upper transmission / reception function unit 11. Further, the lower transmission / reception function unit 12 transfers the upstream signal to the traffic information acquisition unit 14. The lower transmission / reception function unit 12 may output only the upstream main signal to the traffic information acquisition unit 14.

  The traffic information acquisition unit 14 monitors the traffic of the uplink signal. The traffic information acquisition unit 14 outputs traffic information indicating a traffic monitoring result to the traffic amount estimation unit 15, the traffic transmission cycle / timing extraction unit 16, and the bandwidth allocation amount calculation unit 17. Hereinafter, the traffic monitoring result is, for example, time-series traffic data in which the time is associated with the traffic amount of the uplink signal transmitted from each lower-level device 6.

  The traffic volume estimating unit 15 extracts traffic estimation information that is information necessary for estimating the traffic volume. First, the traffic amount estimating unit 15 extracts a traffic pattern that is a fluctuation cycle of traffic based on the traffic monitoring result of the plurality of terminal devices 2 indicated by the traffic information, and extracts a traffic pattern from the start to the end of one traffic pattern. Divide the period into one or more time slots. Subsequently, the traffic amount estimating unit 15 calculates statistical information of the traffic amount in each time slot based on the traffic information for each lower device 6. The statistical information on the traffic volume is an average traffic volume in each time slot and a variance of the traffic volume. The traffic amount estimating unit 15 transfers the timing of the end and start of each time slot and the statistical information of the traffic amount for each time slot of each lower-level device 6 to the bandwidth allocation amount calculating unit 17 as traffic estimation information.

  The traffic transmission cycle / timing extraction unit 16 estimates the traffic transmission cycle and the start timing of the traffic transmission cycle based on the traffic monitoring results of all the terminating devices 2 indicated by the traffic information. The traffic transmission cycle corresponds to a TTI. One TTI includes one or more DBA periods. The traffic transmission cycle / timing extraction unit 16 outputs the estimated traffic transmission cycle and the start timing of the traffic transmission cycle to the bandwidth allocation calculation unit 17.

At the time of traffic collection before performing variable bandwidth allocation, the bandwidth allocation amount calculation unit 17 allocates a fixed bandwidth to the terminating device 2 in each DBA cycle. When performing the variable bandwidth allocation, the bandwidth allocation amount calculation unit 17 allocates the bandwidth to the terminating device 2 connected to each lower device 6 for each time slot as shown in FIG. I do. That is, when the fixed bandwidth (1) is allocated, the bandwidth allocation calculation unit 17 calculates one TTI worth of the TTI assuming that the average traffic volume of the lower order device 6 estimated by the traffic volume estimation unit 15 will continue to occur. The time t _avr required to transmit the estimated traffic volume is calculated. The fixed band (1) is a band larger than a band for averaging and transmitting an estimated traffic amount for one TTI during a period of one TTI. Further, the bandwidth allocation calculation unit 17 adds a time corresponding to the variance of the traffic amount estimated by the traffic amount estimation unit 15 to the calculated time t _avr to calculate the time t _end . The bandwidth allocation calculation unit 17 allocates the fixed band (1) to the DBA cycle including the time t _avr from the start of the TTI, and includes the time t _end from the DBA cycle following the DBA cycle to which the fixed bandwidth (1) is assigned. The fixed bandwidth (2) is allocated to the DBA cycle, and no bandwidth is allocated to the remaining DBA cycles from the DBA cycle following the DBA cycle to which the fixed bandwidth (2) is allocated to the start of the next TTI. The fixed band (2) may be the same as or different from the fixed band (1).

  As described above, since a fixed bandwidth larger than the bandwidth in the case where the estimated traffic volume is averaged and transmitted from the start of the TTI is allocated, the transmission delay of the upstream traffic in the terminal device 2 is reduced even when burst traffic occurs. Can be. In addition, since the traffic distribution can increase the traffic cycle for allocating the bandwidth, the delay of the upstream traffic transmitted from the terminating device 2 can be reduced even in the case of a time slot or a lower device 6 in which the traffic varies greatly. it can.

  The bandwidth allocation function unit 18 allocates a bandwidth to the terminal device 2 according to a control schedule based on a time change of the bandwidth allocation amount within one TTI in each time slot of the terminal device 2 calculated by the bandwidth allocation amount calculation unit 17. The bandwidth allocation function unit 18 notifies each terminal device 2 of the bandwidth allocation amount in each DBA cycle according to the control schedule. The terminal device 2 transmits an uplink signal to the terminal device 1 according to the notified bandwidth allocation amount in each DBA cycle.

FIG. 3 is a flowchart showing a band allocation process in the terminal station device 1.
First, the bandwidth allocation function unit 18 of the terminal station device 1 fixedly allocates a bandwidth to each terminal device 2 in each DBA cycle for traffic collection. The lower transmission / reception function unit 12 notifies each terminal device 2 of the fixed bandwidth allocated by the bandwidth allocation function unit 18 as the allocated bandwidth of each DBA cycle. Each terminal device 2 transmits the uplink data received from the lower device 6 to the terminal device 1 according to the allocated band. The lower transmission / reception function unit 12 of the terminal station device 1 transfers the upstream signal received from the terminal device 2 to the traffic information acquisition unit 14 (Step S110).

  The traffic amount estimating unit 15 estimates a traffic cycle based on the traffic monitoring result, and divides the estimated traffic cycle into one or more time slots. The traffic volume estimation unit 15 calculates the average traffic volume of each time slot and the variance of the traffic volume for each lower device 6 based on the traffic monitoring result (step S120).

For example, the traffic amount estimating unit 15 estimates a traffic cycle as one day from received data traffic over a plurality of days, and divides the traffic cycle into several time slots such as morning, daytime, and night. The traffic amount estimating unit 15 calculates an average traffic amount R _avg [N _slot ] and a variance σ [N _slot ] of the traffic amount in each time slot for each lower-level device 6. N _slot represents a time slot number of received data traffic. For example, when the time slot is divided into three time slots of morning, daytime, and night, _Nslot takes a value of 0, 1, or 2. It is also possible to take time slots more precisely. The estimation result of the traffic volume is used for bandwidth allocation. The traffic amount estimating unit 15 sends the timing of the end and start of the time slot, and the statistical information in which the average traffic amount and the variance value of the traffic amount of each time slot for each lower-level device 6 are set to the bandwidth allocation amount calculating unit 17. Forward. This statistical information represents the estimated traffic volume that will occur in each time slot in the future.

  Further, the traffic information acquisition unit 14 transfers the traffic information to the traffic transmission cycle / timing extraction unit 16. The traffic transmission cycle / timing extraction unit 16 extracts the start timing of one TTI and the transmission cycle based on the traffic information (step S130). For example, the traffic transmission cycle / timing extraction unit 16 determines the timing at which the traffic volume shifts from 0 or near 0 to a traffic volume exceeding a threshold for detecting the occurrence of traffic as a candidate for the head timing of the transmission cycle, The head timing and transmission period of one TTI are estimated based on the time intervals at which timing candidates appear. The traffic information acquisition unit 14 transfers the estimated start timing of one TTI and the transmission cycle to the bandwidth allocation calculation unit 17.

  The bandwidth allocation calculation unit 17 calculates the timing of bandwidth allocation and the bandwidth allocation in each time slot for each terminal device 2 connected to each lower-level device 6 (step S140). FIG. 4 is a diagram illustrating a bandwidth allocation method by the bandwidth allocation amount calculation unit 17. The bandwidth allocation calculation unit 17 performs the following processing for each time slot for each of the terminating devices 2 connected to each of the lower-level devices 6. In other words, based on the statistical information of the traffic volume of the lower-level device 6 in the time slot to which the bandwidth is allocated, the head timing of the 1 TTI, and the transmission cycle, the bandwidth allocation amount calculation unit 17 allocates the bandwidth within the 1 TTI cycle in the time slot. The amount is determined in DBA cycle units. The bandwidth allocation amount calculation unit 17 performs fixed bandwidth allocation in the DBA cycle that matches the beginning of the 1TTI cycle, and transfers signals without delay. When the traffic is smaller than the traffic at the peak, there is an area where no signal is generated at the tail in one TTI cycle. The bandwidth allocation calculation unit 17 can reduce the bandwidth used by the mobile system by making the allocated bandwidth in the DBA cycle corresponding to this area variable.

  The bandwidth allocation amount R (t) at time t according to the bandwidth allocation method shown in FIG. 4 can be generalized by the following equation.

Here, R _max is the maximum band that can be allocated, and t _avg and t _end are the times calculated based on the traffic volume estimation result by the traffic volume estimation unit 15. The time of 1 TTI is set to 0. When α (t) takes an arbitrary constant, α (t) R _max is equal to or more than R _avg [N _slot ].

Assuming that the estimated average traffic amount _Ravg indicated by the statistical information is transferred during one TTI, the signal is transferred at the full rate from the beginning of 1TTI as shown in FIGS. 12 and 13, and the signal is transferred by _tavg. Is completed, t _avg is represented by a linear mapping of the estimated average traffic amount R _avg as in the following equation (4).

Here, t _TTI is a length of 1 _TTI , and in the case of LTE, t _TTI is 1 ms. In Equation (3), t _end represents the end time of the bandwidth allocation in one TTI. Bandwidth allocation amount calculating unit 17 calculates the _{t avg} by the formula (4) with _R avg _{[N slot]} of the lower device 6 shown by statistics. t _end is calculated as in the following equation (5).

t _σ is a linear mapping of the variance σ, similar to equation (4). In equation (4), t _avg was calculated from the estimated average traffic volume. t _σ is represented by the following equation (6).

The bandwidth allocation calculation unit 17 calculates t _{σ according} to the equation (6) using the variance σ [N _slot ] of the traffic amount of the lower device 6 indicated by the statistical information, and calculates the equation using the calculated t _{σ. Tend} is calculated by (5). In Expression (5), γ is a positive real number determined based on the risk factor P required for the communication system. The bandwidth allocation amount calculating unit 17 may store γ in advance, by using a predetermined calculation formula from the risk factor P stored in advance, or by reading from a table in which the risk factor P and γ are associated with each other, γ may be obtained. The value of γ increases as the risk factor P decreases. Also, the traffic risk estimation unit 15 may instruct the bandwidth allocation calculation unit 17 of the risk factor P.

The bandwidth allocation calculator 17 allocates a bandwidth in DBA cycle units based on t _avg and t _end . The bandwidth allocation calculator 17 allocates the bandwidth allocation α (t) R _max (α is an arbitrary constant) to the DBA cycle including the time t _avr from the start of the TTI. The bandwidth quota calculation unit 17 allocates β (t) (β is an arbitrary constant) from the DBA cycle following the DBA cycle including the time t _avr to the DBA cycle including the time t _end . However, when the time t _avr and the time t _end are included in one DBA cycle, the bandwidth assignment amount α (t) R _max (α is an arbitrary constant) is assigned to the DBA cycle. After the DBA cycle including the time t _end , the bandwidth assignment amount calculation unit 17 does not assign a bandwidth for the DBA cycle until the next TTI starts.

By setting t _end , a surplus band is allocated as compared with the case where band allocation is performed from the beginning of 1 TTI to time t _avg, so that it is possible to cope with a case where traffic exceeding the average traffic volume flows in. It becomes possible. Furthermore, the DBA cycle from the _{end of the} allocation not being performed until the start time of the next TTI may be based on, for example, housing another system such as FTTH (Fiber to the home), or a terminal connected to a mobile base station. It can be used as a period for putting the device 2 (ONU) to sleep or accepting a newly connected terminating device 2 (new ONU).

  For example, when 1 TTI = 1 ms, DBA cycle is 125 μs, and 4 Grant / DBA cycle, 1 TTI (1 ms) can be divided into 32 resolutions. A band is fixedly allocated from the top during this resolution. Here, if a band is allocated to 18 resolutions based on the traffic volume estimation result, the sleep state is set without allocating a band to the 19th to 32nd resolutions.

  Further, the traffic volume corresponding to the case where traffic exceeding the average traffic volume flows in can be determined by the risk factor P.

Note that the time in Expressions (1) to (6) is expressed as an elapsed time when the head of the TTI is defined as t = 0. When the time transits to the beginning of the next TTI cycle after the lapse of the time t _avg , t _end , t _TTI from 0 second, the time t = 0.

The bandwidth allocating function unit 18 terminates the terminal device 2 according to the control schedule based on the time change of the bandwidth quota within one TTI in each time slot calculated by the bandwidth quota calculating unit 17 for the terminating device 2 connected to each lower-level device 6. A bandwidth is allocated to the device 2 in each DBA cycle (step S150). The terminating device 2 transmits the uplink signal received from the lower order device 6 to the terminal device 1 in accordance with the band allocated for each DBA cycle.
Note that the terminal device 1 may perform Step S120 and Step S130 in parallel.

  The traffic information acquisition unit 14, the traffic volume estimation unit 15, the traffic transmission cycle / timing extraction unit 16, the bandwidth allocation calculation unit 17, and the bandwidth allocation function unit 18 in FIG. However, it is also possible to provide all or a part of them in a band allocating device that is an external device of the terminal device 1. In addition, the present embodiment is not limited by the network topology. That is, the present invention can be realized not only in the PON system but also in a network topology such as a ring configuration or a bus configuration.

[Second embodiment]
In the first embodiment, bandwidth allocation is performed based on equations (1) to (6). However, there is a possibility that traffic that greatly exceeds the estimation result may occur. Therefore, in the second embodiment, when traffic exceeding the estimated bandwidth allocation occurs, the bandwidth allocation state is shifted to the initial state. Hereinafter, the description will focus on the differences from the first embodiment.

  FIG. 5 is a functional block diagram illustrating the configuration of the terminal device 1a according to the present embodiment. In the figure, the same portions as those of the terminal device 1 according to the first embodiment shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. The terminal device 1a according to the present embodiment differs from the terminal device 1 according to the first embodiment in that a traffic information acquisition unit 14a is provided instead of the traffic information acquisition unit 14, and a traffic determination time threshold processing unit. 19 is further provided.

  The traffic information acquisition unit 14a has a function similar to that of the traffic information acquisition unit 14 of the first embodiment. The traffic information acquisition unit 14a transfers the traffic monitoring result to the traffic volume estimation unit 15, the traffic transmission cycle / timing extraction unit 16, the bandwidth allocation calculation unit 17, and the traffic determination time threshold processing unit 19.

The traffic determination time threshold processing section 19 sets an arbitrary time threshold t _th . t _avg <t _th <t _end . Traffic determination time threshold processing unit 19, when the traffic volume has occurred beyond a time threshold t _th In certain TTI, instructs the bandwidth allocator 18 to allocate a fixed bandwidth of invariant time to each terminal device 2.

FIG. 6 is a diagram illustrating an operation in the terminal device 1a. When the traffic determination time threshold value processing unit 19 of the terminal station device 1a detects the occurrence of the traffic volume exceeding the time threshold value t _th in a certain TTI, the bandwidth allocation function unit 18 sends the time-invariant fixed value to each of the terminal devices 2. Allocate bandwidth. The terminal station device 1a performs traffic collection again, estimates a traffic amount based on the collected traffic information, and performs band allocation. By this processing, the influence of delay and throughput on the radio base station when the estimation is deviated is minimized.

FIG. 7 is a flowchart showing a band allocation process in the terminal station device 1a. In the figure, the same processes as those of the band allocation process according to the first embodiment shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. The terminal device 1a performs the processing of steps S110 to S150 shown in FIG. The traffic determination time threshold processing unit 19 determines whether or not the traffic volume has exceeded the time threshold t _th in a certain TTI (step S160). When the traffic determination time threshold value processing unit 19 does not detect that the traffic amount has exceeded the time threshold value t _th , the processing from step S150 is repeated, and when it is detected, the processing from step S110 is repeated.

[Third Embodiment]
In the case of the second embodiment, when the time exceeds the time threshold t _th , re-estimation is immediately performed. However, if the increase in traffic is a temporary case, an excessive number of re-bandwidth allocations will be performed. Therefore, when the time threshold value t _th is exceeded by a predetermined number over a plurality of TTIs, the re-allocation of the bandwidth and the estimation of the traffic amount according to the second embodiment are performed again. This makes it possible to prevent the second embodiment from being operated excessively. Hereinafter, the description will focus on the differences from the second embodiment.

The terminal device of the present embodiment is the same as the terminal device 1a of the second embodiment shown in FIG.
FIG. 8 is a flowchart illustrating a bandwidth allocation process in the terminal device 1a according to the present embodiment. In the figure, the same processes as those of the band allocation process according to the first embodiment shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. The terminal device 1a performs the processing of steps S110 to S150 shown in FIG. The traffic determination time threshold processing unit 19 determines whether or not the traffic volume has exceeded the time threshold t _th in a certain TTI (step S160). If the traffic determination time threshold value processing unit 19 does not detect that the traffic amount has exceeded the time threshold value t _th , the process from step S150 is repeated, and if detected, the process of step S170 is performed.

  The traffic determination time threshold value processing unit 19 updates the current value of the counter whose initial value is 0 by adding 1 to the current value (step S170). The traffic determination time threshold processing unit 19 determines whether the value of the counter has exceeded a predetermined threshold (Step S180). When the traffic determination time threshold processing unit 19 determines that the value of the counter is equal to or smaller than the threshold, the processing from step S150 is repeated, and when it is determined that the value exceeds the threshold, the processing from step S110 is repeated.

[Fourth embodiment]
In the first to third embodiments, the terminal station device obtains uplink traffic, estimates traffic information, and performs bandwidth allocation. The terminal station device acquires only downlink traffic or both upper and lower traffic instead of uplink traffic, and performs the same processing as in the first to third embodiments using the acquired traffic information. Is also good.

[Fifth Embodiment]
When the relay transmission system accommodates a plurality of RRHs, the terminal device 1 extracts the time and traffic time of the traffic patterns of the above-described first to fourth embodiments for each of the terminal devices 2 connected to the RRHs. Dividing into slots, extracting the start timing of one TTI and the transmission cycle, makes it possible to enhance the band reduction effect. In addition, since the head of the TTI differs depending on the RRH, it is possible to cope with it by performing individual extraction.

According to the embodiment described above, the bandwidth allocating device (for example, the terminal device 1, 1a) includes a traffic information acquiring unit (for example, the traffic information acquiring unit 14, 14a) and a traffic amount estimating unit (for example, the traffic amount). An estimating unit 15), a traffic transmission cycle estimating unit (for example, a traffic transmission cycle / timing extracting unit 16), a bandwidth quota calculating unit (for example, a bandwidth quota calculating unit 17), and a bandwidth allocating function unit (for example, a bandwidth allocating unit). Allocation function units 18 and 18a).
The traffic information acquisition unit acquires, for each lower-level device connected to the terminating device, traffic information indicating a time-series traffic volume of communication performed by the lower-level device via the terminating device. The traffic amount estimating unit extracts a traffic fluctuation period based on the traffic information, and divides the extracted fluctuation period into one or more time slots. The traffic transmission cycle estimating unit estimates a traffic transmission cycle and a start timing of the traffic transmission cycle based on the traffic information. The bandwidth allocation calculation unit obtains, from the traffic information, a bandwidth to be allocated to the terminal device connected to the lower-level device in the traffic transmission cycle included in the time slot based on the traffic information and the traffic transmission cycle and the start timing thereof. The bandwidth required for transmission of the traffic volume estimated by the lower-level device is temporally switched so as to be allocated from the start timing of the traffic transmission cycle to the timing before the start timing of the next traffic transmission cycle. The bandwidth allocation function unit allocates a bandwidth to the terminal device according to a control schedule based on the bandwidth allocated by the bandwidth allocation amount calculation unit.

  The traffic volume estimating unit may acquire the average value and the variance value of the traffic volume of the lower-level device based on the traffic information for each time slot. The bandwidth allocation amount calculation unit, in the traffic transmission cycle, the timing to switch the bandwidth allocated to the terminal device connected to the lower device, the average value and the variance of the traffic amount of the lower device in the time slot that includes the traffic transmission cycle, It is calculated based on the risk factor.

  In the traffic transmission cycle, the bandwidth quota calculation unit sets the bandwidth required for transmission of the estimated traffic volume of the lower device obtained from the traffic information before the start timing of the next traffic transmission cycle from the start timing of the traffic transmission cycle. After that, a surplus band for transmitting traffic exceeding the estimated traffic is allocated to the next time zone.

  The bandwidth allocation function unit allocates a fixed bandwidth that does not change with time to a terminal device connected to the lower-level device when traffic of the lower-level device occurs beyond a predetermined timing in a time zone to which the surplus bandwidth is allocated. Alternatively, when the number of times the traffic of the lower-level device has occurred beyond a predetermined timing in the time zone to which the surplus bandwidth has been allocated is equal to or greater than the threshold, the band allocation function unit may transmit the time to the terminal device connected to the lower-level device. A fixed band that does not change due to is assigned. The bandwidth allocation amount calculation unit newly calculates a bandwidth to be temporally switched and assigned to the terminal device in the traffic transmission cycle based on the traffic information acquired by the traffic information acquisition unit when the fixed bandwidth is allocated.

  In a conventional bandwidth allocation method based on traffic estimation, a large delay may be given when a signal from a wireless base station is transferred. According to the embodiment described above, the terminal device estimates the traffic amount, and changes the bandwidth allocation amount within one TTI period for each DBA period based on the estimation result. The terminal device performs fixed band allocation in the DBA cycle that coincides with the beginning of the 1TTI cycle, and transfers signals without delay. When the traffic is smaller than the traffic at the peak, there is an area where no signal is generated at the tail in one TTI cycle. The terminal device changes the allocated bandwidth in the DBA cycle corresponding to this area. As described above, since the bandwidth is assigned based on the traffic amount, it is possible to suppress excessive bandwidth assignment. Therefore, it is possible to use the ONU which is accommodated by another system, during which the ONU connected to the mobile base station is put to sleep, and during which a newly connected ONU is accepted.

  Some functions of the terminal devices 1 and 1a in the above-described embodiment may be realized by 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 and executed by a computer system. Here, the “computer system” 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, and a CD-ROM, and a storage device such as a hard disk built in a computer system. Further, the “computer-readable recording medium” refers to a communication line for transmitting a program via a network such as the Internet or a communication line such as a telephone line. Such a program may include a program that holds a program for a certain period of time, such as a volatile memory in a computer system serving as a server or a client in that case. Further, the above-mentioned program may be for realizing a part of the above-mentioned functions, and may be for realizing the above-mentioned functions in combination with a program already recorded in the computer system.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments and includes a design and the like within a range not departing from the gist of the present invention.

  The present invention can be applied to a communication system that performs communication by the TDMA method.

1, 1a Terminal device 2 Terminal device 3 Optical splitter 5 Upper device 6 Lower device 11 Upper transmission / reception function unit 12 Lower transmission / reception function unit 14, 14a Traffic information acquisition unit 15 Traffic amount estimation unit 16 ... Traffic transmission cycle / timing extraction unit 17 ... Band allocation amount calculation unit 18 ... Band allocation function unit 19 ... Traffic determination time threshold processing units 41 and 42 ... Optical fiber

Claims (5)

For each lower device connected to the terminating device, a traffic information acquisition unit that acquires traffic information indicating a time-series traffic amount of communication performed by the lower device through the terminating device,
A traffic amount estimating unit that extracts a fluctuation period of traffic based on the traffic information and divides the extracted fluctuation period into one or more time slots;
A traffic transmission cycle based on the traffic information, and a traffic transmission cycle estimation unit that estimates a start timing of the traffic transmission cycle;
In each of the time slots, based on the traffic information and the traffic transmission cycle and the start timing, the bandwidth required for transmitting the estimated traffic volume of the lower-level device obtained from the traffic information is the traffic transmission cycle. The end device connected to the lower-order device in the traffic transmission cycle included in the time slot, so that the end device is allocated between the start timing and the timing before the start timing of the next traffic transmission cycle. A bandwidth quota calculator for changing the bandwidth to be allocated according to time ;
A band allocation function unit that performs band allocation to the terminal device according to a control schedule based on a band allocated by the band allocation amount calculation unit;
A bandwidth allocating apparatus comprising: The traffic amount estimating unit, for each of the time slots, acquires an average value and a variance value of the traffic amount of the lower order device based on the traffic information,
In the traffic transmission cycle, the bandwidth allocation amount calculation unit determines a timing for switching a bandwidth to be allocated to the terminating device connected to the lower device, by changing the traffic volume of the lower device in the time slot including the traffic transmission period. Calculated based on the average value and the variance value, and the risk factor,
The bandwidth allocating apparatus according to claim 1, wherein: In the traffic transmission cycle, the bandwidth allocation calculation unit calculates a bandwidth required for transmission of the estimated traffic volume of the lower device obtained from the traffic information from the start timing of the traffic transmission cycle. After allocating to a time period up to the timing before the start timing, a surplus band for transmitting traffic exceeding the estimated traffic is allocated to the next time period,
3. The bandwidth allocating apparatus according to claim 1, wherein: The bandwidth allocation function unit is configured such that, when traffic of the lower-level device occurs beyond a predetermined timing in a time zone to which the surplus bandwidth is allocated, the terminal device connected to the lower-level device does not change with time. Allocate fixed bandwidth,
The bandwidth allocation calculation unit, based on the traffic information obtained by the traffic information acquisition unit when the fixed bandwidth is allocated, the time to switch in the traffic transmission cycle to allocate the bandwidth to be allocated to the terminal device. Newly calculated,
The bandwidth allocating apparatus according to claim 3, wherein: The bandwidth allocation function unit is configured to, when the number of times that traffic of the lower-level device has occurred beyond a predetermined timing in a time zone in which the surplus bandwidth is allocated is equal to or greater than a threshold, the termination connected to the lower-level device. Allocate fixed bandwidth that does not change with time to the device,
The bandwidth allocating apparatus according to claim 4, wherein:

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