JP5634309B2 - Band reservation apparatus and method, communication apparatus, and communication system - Google Patents

Description

  The present invention relates to a band reservation apparatus and method in a communication system that performs communication by reserving a band necessary for data transmission, and a communication apparatus and communication system including such a band reservation apparatus.

  In recent years, there has been an increasing need for transmitting content that emphasizes real-time properties such as video and audio via a communication network, and a bandwidth and QoS (Quality Of Service) that satisfy the requirements for content transmission. Securing is required. In particular, in a network environment where the available bandwidth is limited, a bandwidth used for data transmission in order to avoid collision of each other's data when a plurality of communication devices perform data transmission while ensuring QoS. In addition, a bandwidth allocation process that divides and allocates time has been performed.

  In addition, in a communication system that transmits data using a communication channel selected from a plurality of communication channels, a band for transmitting content is generated in the communication channel selected and used due to the occurrence of disturbance noise. Processing to ensure QoS by moving to or changing to a communication channel other than the communication channel being used, and performing bandwidth allocation processing in the destination communication channel and continuing to transmit content when the reservation becomes impossible Was done.

  However, during the time when the communication channel is changed, the band for transmitting the content is not allocated, so that the content cannot be transmitted. In response to this, generally, a transmission data buffer is prepared on the transmitter side, and when content transmission is not possible, it is temporarily stored in the transmission data buffer, the change of the communication channel is completed, and content transmission resumes. After that, the data temporarily transmitted in the transmission data buffer was transmitted.

  However, while the communication channel is being changed, the content transmission stops, so the remaining data amount in the transmission data buffer increases monotonously. Furthermore, even if the change of the communication channel is completed and the content transmission is resumed, only the bandwidth based on the bit rate of the content is allocated, so even if the remaining data amount of the transmission data buffer does not decrease or decreases The rate of decline was low.

  The transmit data buffer is also used to absorb temporary disturbance noise and transmission disturbance during congestion, but the amount of data that can be additionally stored as the remaining data in the transmit data buffer increases. There is a problem that the ability to absorb temporary disturbance noise and transmission disturbance during congestion decreases.

  As a technology to reduce the time required for bandwidth allocation processing, in order to secure the bandwidth required for data transmission, it is reserved by setting the bandwidth and time required for data transmission declared by the user in advance. There is a proposal for quickly allocating a bandwidth necessary for data transmission occurring at a certain time (see, for example, Patent Document 1).

JP-A-6-30021

  As described above, when changing a communication channel, the bandwidth reserved for one communication channel is released, and the time required for completing the bandwidth reservation for another communication channel is the bandwidth for transmitting transmission data. Transmission data is accumulated in the transmission data buffer. In general, since the size of the transmission data buffer is finite, a buffer overflow may occur, and stable communication may not be possible. Further, along with the buffer overflow on the transmission side, a buffer underflow occurs on the reception side, and there is a possibility that complete transmission data cannot be reproduced on the reception side.

  In addition, even if the communication channel is changed to the other communication channel, if only the reserved bandwidth amount based on the bit rate of the content data is allocated, the remaining data amount of the transmission data buffer does not decrease and the buffer overflow There is a risk that a period during which stable communication cannot be performed will occur.

  The technique according to Patent Document 1 can be executed when parameters such as a bandwidth and a usage time necessary for data transmission are determined in advance before starting data transmission. However, the change of the communication channel may be executed due to the deterioration of the communication status due to noise generated in the communication channel being used, in which case reservation processing cannot be performed in advance, After all, there was a possibility that stable communication could not be performed.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a bandwidth reservation device and method capable of stably performing data transmission by a communication device, and such a bandwidth. It is to provide a communication apparatus and a communication system including a reservation apparatus.

The bandwidth reservation apparatus according to one aspect of the present invention includes:
A transmission band reservation type communication system comprising a transmission data buffer for temporarily storing the transmission data during a period from transmission data input to transmission of the transmission data to a communication network, and a plurality of transmission data buffers on the communication network In the communication channel selected from among the communication channels, a bandwidth reservation device of a communication device for reserving a transmission band and transmitting data stored in the transmission data buffer in the reserved transmission band,
A bit rate value notifying unit for detecting and notifying a bit rate value of the transmission data;
From the bit rate value of the transmission data, a first bandwidth reservation amount calculation unit that calculates a bandwidth amount necessary for transmission in the communication network as a first bandwidth reservation amount;
When the communication channel used for transmission of the transmission data is changed, the bandwidth reservation blank time which is the time until the reserved bandwidth acquired in the communication channel before the change is released and the bandwidth is reserved in the channel after the change A second bandwidth reservation amount calculation unit for calculating an additional bandwidth for reducing the data accumulated in the transmission data buffer by transmission on the changed communication channel as a second bandwidth reservation amount;
During the time when the communication channel for transmitting the transmission data is changed, the reserved bandwidth is released,
A bandwidth reservation control unit that reserves a combined bandwidth reservation amount of the first bandwidth reservation amount and the second bandwidth reservation amount in a time for transmitting transmission data on the communication channel after the change ,
The second bandwidth reservation amount calculation unit,
A bit rate of the transmission data or a value obtained by integrating the first bandwidth reservation amount over the bandwidth reservation blank time is calculated as a data amount accumulated in the transmission data buffer in the bandwidth reservation blank time,
A value obtained by dividing the data amount by the second bandwidth reservation amount is calculated as a time until the remaining data amount of the transmission data buffer becomes zero or a predetermined value close to zero,
The second bandwidth reservation amount is added for the calculated time .

Moreover, the bandwidth reservation method according to another aspect of the present invention includes:
A transmission band reservation type communication system comprising a transmission data buffer for temporarily storing the transmission data during a period from transmission data input to transmission of the transmission data to a communication network, and a plurality of transmission data buffers on the communication network A bandwidth reservation method in a communication device for reserving a transmission band in a communication channel selected from among the communication channels and transmitting data stored in the transmission data buffer in the reserved transmission band,
A bit rate value notification step of detecting and notifying a bit rate value of the transmission data;
A first bandwidth reservation amount calculation step of calculating a bandwidth amount necessary for transmission in the communication network as a first bandwidth reservation amount from the bit rate value of the transmission data;
When the communication channel used for transmission of the transmission data is changed, the bandwidth reservation blank time which is the time until the reserved bandwidth acquired in the communication channel before the change is released and the bandwidth is reserved in the channel after the change A second bandwidth reservation amount calculating step for calculating, as a second bandwidth reservation amount, an additional bandwidth for reducing the data accumulated in the transmission data buffer by transmission on the changed communication channel;
The reserved bandwidth is released during the time when the communication channel for transmitting the transmission data is changed, and the first bandwidth reservation amount and the second bandwidth reservation amount are set during the time when the transmission data is transmitted on the changed communication channel. and a bandwidth reservation control step of reserving a synthetic bandwidth reservation amount and,
The second bandwidth reservation amount calculating step includes:
A bit rate of the transmission data or a value obtained by integrating the first bandwidth reservation amount over the bandwidth reservation blank time is calculated as a data amount accumulated in the transmission data buffer in the bandwidth reservation blank time,
A value obtained by dividing the data amount by the second bandwidth reservation amount is calculated as a time until the remaining data amount of the transmission data buffer becomes zero or a predetermined value close to zero,
The second bandwidth reservation amount is added for the calculated time .

  According to the present invention, there is an effect that the data remaining amount of the transmission data buffer can be quickly reduced and data transmission can be performed stably.

It is a figure which shows schematically the structure of the communication system which concerns on Embodiment 1 and 2 of this invention. FIG. 2 is a block diagram schematically showing a configuration of a transmission device used in the communication system of FIG. 1. It is a figure which shows the super-frame structure in ECMA-386 specification. It is a figure which shows the frequency arrangement | positioning of the communication channel in the radio | wireless communication system of a UWB (Ultra Wideband) system. It is a figure which shows an example of the time change of the bit rate value of the video data input into the transmitter which concerns on Embodiment 1 and 2, and an example of the time change of the 1st zone reservation amount. FIG. 10 is a diagram showing an example of a temporal change in the remaining amount of data in a transmission data buffer of the transmission apparatus according to Embodiments 1 and 2. It is a figure which shows an example of the time change of the synthetic | combination band reservation amount at the time of the change of the communication channel which concerns on Embodiment 1 and 2. FIG. It is a figure which shows an example of the time change of the data remaining amount of the transmission data buffer of the band reservation apparatus which concerns on Embodiment 1 and 2. FIG. It is a block diagram which shows roughly the structure of the transmitter which concerns on Embodiment 2 of this invention. 10 is a diagram illustrating an example of a temporal change in the remaining amount of data in a transmission data buffer of the transmission apparatus according to Embodiment 2. FIG. 10 is a diagram illustrating an example of a temporal change in the remaining amount of data in a transmission data buffer of the transmission apparatus according to Embodiment 2. FIG.

Embodiment 1 FIG.
FIG. 1 schematically shows a configuration example of a communication system including a communication apparatus including a bandwidth reservation apparatus according to Embodiment 1 of the present invention.

The communication system shown in FIG. 1 includes a plurality of communication devices that can communicate with each other via a communication network 3. FIG. 1 shows a first communication device 1 and a second communication device 2 among a plurality of communication devices. The first communication device 1 is used as a transmission device, for example, and the second communication device 2 is used as a reception device, for example. In the illustrated example, a content supply source 4 is connected to the transmission device 1, and a content processing device 5 is connected to the reception device 2.
Note that the configuration of the communication system is not limited to the illustrated example, and may be a configuration that does not include the content processing device 5, and various modifications are possible.

  The illustrated communication system performs data transmission by bandwidth reservation type media access control, and the communication network 3 includes means for performing bandwidth reservation type media access control, for example, access control means 3a. The apparatus selects one communication channel from among a plurality of communication channels on the communication network 3, performs bandwidth reservation on the selected communication channel, and performs communication using the reserved bandwidth.

The content data D1 in which real-time property is emphasized, such as video and audio, is input from the content supply source 4 to the transmission device 1, and the content data D1 is transmitted as the transmission data D2 via the communication network 3, It is transmitted to the receiving device 2.
The receiving device 2 outputs data D3 based on the content data D1 included in the received transmission data D2 to the content processing device 5.

  The content processing device 5 processes the content based on the received data D3. The data supplied from the content supply source 4 to the transmission device 1 may be only video data, or may be transmission data composed of video data and data other than video data, or transmission data that is not video data. The content processing device 5 may be a device that performs processing other than video display as long as it is a device that performs processing based on the transmission signal received by the receiving device 2.

  Hereinafter, a case where the content data D1 is video data and the content processing device 5 is a device that performs video display (video display device) will be described. In that case, the content processing apparatus 5 reproduces and displays the video based on the received data D3.

  The communication network 3 may be any network that adopts any communication method as long as it adopts a communication method that performs media access control of the bandwidth reservation method.

  In this embodiment, the communication network 3 uses a wireless communication system of the European Computer Manufacturers Association standard ECMA (European Computer Manufacturer Association) -368 and UWB (Ultra Wideband) standardized as ECMA-369. I decided to. This wireless communication method is a wireless communication method equivalent to the WiMedia standard, which is standardized by the WiMedia Alliance.

FIG. 2 schematically shows a configuration example of the transmission apparatus 1 of FIG.
2 includes a data input unit 11, a transmission data buffer 12, a bit rate notification unit 13, a first bandwidth reservation amount calculation unit 14, a wireless communication unit 15, and a communication channel change request unit. 16, a second bandwidth reservation amount calculation unit 17, a bandwidth reservation control unit 18, a clock 19, and a storage unit 22. Among these, a bandwidth reservation device includes a bit rate notification unit 13, a first bandwidth reservation amount calculation unit 14, a second bandwidth reservation amount calculation unit 17, a bandwidth reservation control unit 18, a clock 19, and a storage unit 22. 10 is configured.

Video data D <b> 1 supplied from the content supply source 4 is input to the data input unit 11.
The transmission data buffer 12 temporarily stores the video data during a period from the time when the video data is input to the data input unit 11 to the time when the video data is sent to the communication network 3, for example, FIFO. This is a (First In First Out) format buffer.

  The wireless communication unit 15 transmits video data to the receiving device 2 via the communication network 3 and transmits / receives a signal for bandwidth reservation to / from the access control unit 3a.

  The bit rate value notification unit 13 detects the bit rate value B (also expressed as “B (t)” of the video data input to the data input unit 11, where t indicates time), and the bit rate Output or notify as value information B.

  Based on the bit rate value B (t) notified from the bit rate value notification unit 13, the first band reservation amount calculation unit 14 determines the band required for transmission in the communication network 3 as the first band reservation amount RB 1 (“ RB1 (t) ”).

  The communication channel change request unit 16 requests to change the communication channel for transmitting video data on the communication network 3.

  The second bandwidth reservation amount calculation unit 17 is a second bandwidth reservation amount RB2 ("RB2 (" RB2 ()) which is a reserved bandwidth (additional bandwidth required immediately after the change) after the communication channel is changed. t) ”) is calculated.

  More specifically, when the communication bandwidth used for transmission of transmission data is changed, the second bandwidth reservation amount calculation unit 17 uses the reserved bandwidth acquired in the communication channel (first communication channel) before the change. The data stored in the transmission buffer 12 is transmitted during a period (band reservation blank time) until it is released, changed to the changed communication channel (second communication channel), and reserved for the second communication channel. Therefore, the additional bandwidth necessary for this is calculated as the second bandwidth reservation amount RB2 (t). The addition of the second bandwidth reservation amount RB2 (t) is continued until the time when the accumulated data in the transmission buffer 12 is expected to be zero or a predetermined value close to zero after the communication channel is changed. The two-band reservation amount RB2 (t) becomes zero, and therefore the second band reservation amount RB2 (t) is not added.

  The bandwidth reservation control unit 18 is based on the first bandwidth reservation amount RB1 (t) and the second bandwidth reservation amount RB2 (t) notified from the first bandwidth reservation amount calculation portion 14 and the second bandwidth reservation amount calculation portion 17, respectively. Thus, the wireless communication unit 15 is requested to perform bandwidth reservation control on the communication network 3.

  That is, the bandwidth reservation control unit 18 releases the reserved bandwidth during the time when the communication channel is being changed, while the remaining amount of data in the transmission data buffer 12 is zero or close to a predetermined value after the communication channel is changed. In the period until reaching the value, the total of the first bandwidth reservation amount and the second bandwidth reservation amount is reserved as a combined bandwidth reservation amount, and the remaining data amount in the transmission data buffer 12 is zero or close to zero. After this value is reached, a reservation is made for a combined bandwidth reservation amount equal to the first bandwidth reservation amount.

  The clock 19 provides time information indicating the time synchronized with the access control means 3a.

  As described above, the video data D1 is transmitted from the transmission device 1 to the reception device 2 after the video data D1 is input via the data input unit 11, and then via the communication network 3 by the wireless communication unit 15. Thus, the data is temporarily stored in the transmission data buffer 12 until it is transmitted to the receiving device 2.

  When the transmission state on the communication network 3 is good, an output request for video data is sent from the wireless communication unit 15 to the transmission data buffer 12, and the transmission data buffer 12 that has received this output request is stored. The video data being sent is sent to the wireless communication unit 15.

  If data transmission cannot be performed due to deterioration of the transmission state on the communication network 3, the video data remains stored in the transmission data buffer 12 until a video data output request is received from the wireless communication unit 15. At this time, if the video data D1 continues to be input to the data input unit 11, the video data amount (data remaining amount) accumulated in the transmission data buffer 12 increases.

  The bit rate value notification unit 13 notifies the first band reservation amount calculation unit 14 and the second band reservation amount calculation unit 17 of the bit rate value B (t) of the video data input to the data input unit 11. The bit rate value B (t) of the video data is determined at a certain period by an input interface (not shown) included in the data input unit 11 when the video data is input from the content supply source 4 to the data input unit 11. It can be measured by counting the amount of input data.

  Further, when the bit rate value information of the video data is described in the data accompanying the data (accompanying data) instead of the method of counting the data amount by the input interface (not shown). May adopt a method of extracting the bit rate value information and notifying the first band reservation amount calculation unit 14 and the second band reservation amount calculation unit 17.

  The first bandwidth reservation amount calculation unit 14 is based on the packet error rate PER of video data transmission over the communication network 3 notified from the wireless communication unit 15 and a penalty time PTM described later supplied from the storage unit 22. A bandwidth amount necessary for transmitting video data of the bit rate value B (t) notified from the bit rate value notification unit 13 is calculated.

  First, when it is assumed that no communication error occurs on the communication network 3, the transmission band amount for transmitting video data on the communication network 3 is the bit rate value B (t) notified from the bit rate value notification unit 13. )be equivalent to. For example, when it is notified that the bit rate value B (t) of the video data is 20 Mbps, the transmission bandwidth required for data transmission is 20 Mbps.

However, in general, a communication error may occur in a communication network, and the packet error rate PER becomes a value larger than zero. When a packet error occurs, the packet is retransmitted, and the amount of transmission bandwidth necessary for data transmission increases.
In general, when a packet error occurs, it is necessary to wait for a separately defined time (penalty time) PTM to elapse until the retransmission process starts.
Here, when the packet error rate is expressed as PER (0 ≦ PER <1), the transmission band amount necessary for data transmission is the sum of the geometric sequence having the common ratio as PER. Further, the transmission band amount necessary for data transmission is an infinite series having a public ratio of PER unless the number of retransmissions is limited.

Therefore, the transmission bandwidth DA required for data transmission can be expressed by the following equation (1) using the notified bit rate value B, the penalty time PTM with the bit period as one unit, and the packet error rate PER. it can.

  The first bandwidth reservation amount calculation unit 14 requests the bandwidth reservation control unit 18 to reserve the bandwidth as the first bandwidth reservation amount (first reserved bandwidth request amount) RB1 using the transmission bandwidth amount DA calculated by the equation (1). To do.

  The wireless communication unit 15 transmits video data to the receiving device 2 via the communication network 3. The wireless communication standard of the communication network 3 is not particularly limited as long as it is a wireless communication standard that performs bandwidth reservation type media access control. Here, a case where a wireless communication method of the ECMA-368 standard is used will be described.

  In the ECMA-386 standard wireless communication system, as shown in FIG. 3, a super frame is configured with a period of 65.536 [msec], and this period is a reference for synchronization of communication apparatuses existing in the same network. ing. This super frame is composed of 256 MAS (Media Access Slot) time slots each having a period of 256 μsec. Each communication apparatus reserves a band in each superframe in units of MAS, and performs data transmission using the reserved MAS. In the case of data transmission, such as transmission of video data, in which the amount of communication is small and it is desired to avoid collision with other communications, stable data transmission can be realized by performing bandwidth reservation in units of MAS.

The wireless communication unit 15 determines the optimal transmission rate (physical data rate value) in the physical layer based on communication quality indicators such as received signal strength and packet error rate. In the ECMA-386 standard, the physical data rate value can be selected from eight values of 53.3 Mbps, 80 Mbps, 106.7 Mbps, 160 Mbps, 200 Mbps, 320 Mbps, 400 Mbps, and 480 Mbps.
The wireless communication unit 15 notifies the bandwidth reservation control unit 18 of the selected physical data rate value PDR.

  The bandwidth reservation control unit 18 is based on the first bandwidth reservation amount RB1 (t) (= DA) notified from the first bandwidth reservation amount calculation unit 14 and the physical data rate value PDR notified from the wireless communication unit 15. Then, the number of MAS necessary for transmission of the video data of the bit rate value B is calculated as follows using the physical data rate value PDR.

First, the transmission band DA necessary for transmitting the transmission data input to the data input unit 11 to the receiving device 2 is the total communication capacity (physical data rate) in the selected communication channel of the communication network 3. A ratio RA in the PDR is obtained from the following equation (2).

Since there are 256 MASs in the superframe, the number of MASs necessary for transmission of video data (the number of MASs necessary for transmission of video data among 256 MASs in each superframe) is given by It is not less than the value NA obtained from (3).

When the DA in equation (3) is replaced with the right side of equation (1) and rewritten, the following equation (4) is obtained.

  Since actual bandwidth reservation is performed in units of MAS, it is necessary to reserve bandwidth for the number of MAS rounded up after the decimal point of the value NA obtained by Equation (3) or Equation (4).

算出された値（約２８．４）の小数点以下を切り上げると２９となる。この結果、各スーパーフレーム内の２９個のＭＡＳを予約する必要があることが算出された。 For example, when the bit rate value B of the video data is 20 Mbps, the physical data rate value PDR is 200 Mbps, the packet error rate PER is 0.1, and the penalty time PTM is 0, the necessary number of MASs RM (t) Can be calculated using the equation (4) as in the following equation (5).

29 is obtained by rounding up the calculated value (about 28.4) after the decimal point. As a result, it was calculated that 29 MASs in each superframe need to be reserved.

  The bandwidth reservation control unit 18 calculates the MAS number RM (t) necessary for transmission of video data as described above, and requests the wireless communication unit 15 to reserve the bandwidth of the calculated MAS number RM (t).

  The communication channel change request unit 16 requests movement or change of the communication channel as necessary. Factors for requesting a channel change include a case where a request is made from the outside of the transmission apparatus 1 and a case where a band for transmitting video data cannot be secured due to the occurrence of disturbance noise. Whether or not the band for transmitting the video data can be secured can be determined based on whether or not the number of MASs required for the physical data rate PDR in the physical layer selected by the wireless communication unit 15 can be reserved. The determination result is notified from the wireless communication unit 15 to the communication channel change request unit 16.

  If the wireless communication unit 15 notifies that the band for transmitting the content cannot be secured, the communication channel change request unit 16 requests the wireless communication unit 15 to change the communication channel, The request is also notified to the second bandwidth reservation amount calculation unit 17.

  When the communication channel change request unit 16 requests the communication channel change, the wireless communication unit 15 changes the communication channel used for communication from the currently used communication channel (second communication channel) to the other channel. Change to the communication channel (second communication channel). The second communication channel to be selected is selected from communication channels assigned for each wireless communication system in accordance with laws and wireless communication standards. For example, in a UWB (Ultra Wideband) wireless communication system, communication channels are arranged as shown in FIG. In UWB, communication channels are expressed in terms of bands, and 14 channels from Band 1 (Band # 1) to Band 14 (Band # 14) are allocated. For example, band 1 has a center frequency of 3432 MHz, and band 2 (Band # 2) has a center frequency of 3960 MHz. Of the 14 channels, usable communication channels may be restricted by laws related to radio waves. Of these usable communication channels, a communication channel other than the currently used communication channel is selected as the second communication channel.

  The wireless communication unit 15 may randomly select the second communication channel from among the usable communication channels other than the currently used communication channel, or select them in the band number order. May be.

The wireless communication unit 15 may include a communication state investigation unit (not shown) that examines the communication state of communication channels other than the first communication channel, in addition to the communication unit that communicates with the receiving device 2. This communication state investigation unit sequentially adjusts the frequency to a communication channel other than the first communication channel, and investigates the number of MASs already reserved in the communication channel. For example, other communication shown in FIG. The thing similar to the channel investigation part 21 can be used.
The wireless communication unit 15 may select, as the second communication channel, a communication channel in which the number of MAS reserved by the bandwidth reservation device 10 in the first communication channel can be newly reserved.

  FIG. 5 shows the bit rate value B (t) and the first bandwidth reservation amount RB1 (t) of the video data input to the bandwidth reservation device 10 according to the embodiment when the communication channel used for transmission of the video data is changed. ) Shows an example of the time change.

  The vertical axis in FIG. 5 indicates the bit rate value B (t) and the first bandwidth reservation amount RB1 (t) of the video data, and the horizontal axis indicates time (time) t. In FIG. 5, B1 is the bit rate value of the video data, and RB1 (t) is the first bandwidth reservation amount based on the bit rate value B of the video data. Time T1 is the time when the reserved bandwidth is released on the first communication channel, and time T2 is the time when the first bandwidth reservation amount RB1 (t) is secured on the second communication channel (reserved on the second communication channel). Time when data transmission is possible in the band).

  The second bandwidth reservation amount calculation unit 17 determines the reserved bandwidth reserved in the first communication channel when the communication channel for transmitting video data is changed from the first communication channel to the second communication channel. From the release time T1, the time when the bandwidth reservation of the first bandwidth reservation amount RB1 (t) calculated by the first bandwidth reservation amount calculation unit 14 is completed on the second communication channel (reserved bandwidth in the second channel) The amount of data calculated by integrating the bit rate B (t) of the video data over a period T12 up to T2 is calculated as a bandwidth reservation compensation amount C (t). This calculation is expressed by the following equation (6).

The bit rate B (t) necessary for performing the calculation of Expression (6) is notified from the bit rate notification unit 13.
Time T1 is a reservation release time. For example, a time when a channel change processing start instruction is received from the communication channel change instruction unit 16 is set as a reservation release time.
The time T2 is a time point at which the second communication channel is secured or a time point at which it is expected to be secured, but the time T12 necessary for changing the communication channel is almost constant. The value may be stored in the storage unit 22, supplied from the storage unit 22 to the second bandwidth reservation amount calculation unit 17, and a value obtained by adding the time T12 to the time T1 may be used as the approximate value of the time T2.

  If B (t) is constant during the period T12, the data amount C (t) represented by the equation (6) is the area of the rectangular hatched portion in FIG. 5 (or FIG. 7 described later). , B (t) × T12, C (t) can be obtained.

  The bandwidth reservation compensation amount C (t) indicates a shortage of the reserved bandwidth secured on the communication network 3 in comparison with the bit rate value B (t) of the video data during the period from time T1 to time T2. Value.

  Note that the bandwidth reservation compensation amount C (t) may be calculated using the first bandwidth reservation amount RB1 (t) instead of the video data bit rate B (t). In this case, instead of the bit rate B (t), the first bandwidth reservation amount RB1 (t) is calculated by the second bandwidth reservation amount calculation unit 17 as shown by the dotted line in FIG. Supplied from the unit 14.

  FIG. 6 shows a change over time in the remaining amount of data in the transmission data buffer 12 of the bandwidth reservation apparatus 10 according to the embodiment. Before time T1 (period T11), the data output amount and the data input amount of the transmission data buffer 12 are balanced, and the remaining data amount of the transmission data buffer 12 is other than during an exceptionally long communication failure. The state of almost zero continues. When the reserved bandwidth is released on the first communication channel at time T1, the data output amount from the transmission data buffer 12 becomes 0, and the remaining data amount in the transmission data buffer 12 starts to increase. The increase in the remaining amount of data in the transmission data buffer 12 continues until time T2 when the first bandwidth reservation amount is reserved in the second communication channel (period T12). After time T2, the data output amount and the data input amount of the transmission data buffer 12 are balanced, and the remaining data amount of the transmission data buffer 12 hardly changes.

The more data remaining in the transmission data buffer 12, the more difficult it is to withstand sudden long-term communication failures. When the maximum amount of data that can be stored in the transmission data buffer 12 is indicated by DBF and the remaining amount of data in the transmission data buffer 12 is indicated by DB1, the difference value (DBF−DB1) between them is divided by the bit rate value B of the video data. This value is the communication failure time that can be tolerated by this system. For example, in FIG. 6, the communication failure time E1 that can withstand before time T1 can be calculated by the following equation:
E1 = DBF ÷ B

The communication failure time E2 that can be tolerated after time T2 can be calculated by the following equation.
E2 = (DBF−DB1) ÷ B

  Therefore, as shown in FIG. 6, when the remaining data amount in the transmission data buffer 12 does not decrease after time T2, there is a possibility that a long communication failure time cannot be endured and stable transmission cannot be secured. It is not preferable. In the transmission apparatus 1 of the present embodiment, the remaining data amount in the transmission data buffer 12 is quickly reduced by securing the second bandwidth reservation amount RB2 (t) calculated by the second bandwidth reservation amount calculation unit 17. . The process will be described below.

  First, a method for calculating the second bandwidth reservation amount RB2 (t) in the second bandwidth reservation amount calculation unit 17 will be described. As the second bandwidth reservation amount RB2 (t) is larger, the remaining data amount in the transmission data buffer 12 can be quickly reduced. Therefore, the second bandwidth reservation amount calculation unit 17 may set the maximum transmission bandwidth that can be reserved in the communication network 3 as the second bandwidth reservation amount RB2 (t). In other words, the second bandwidth reservation amount calculation unit 17 may set the second bandwidth reservation amount RB2 (t) so as to reserve all MASs that are not reserved in the communication network 3.

  However, on the other hand, if the second bandwidth reservation amount RB2 (t) is set to be large and the bandwidth is reserved, the number of MASs not reserved for bandwidth on the communication network 3 decreases, and other data communication using the same communication network 3 is performed. Has the disadvantage of making it difficult to reserve bandwidth. Therefore, the second bandwidth reservation amount calculation unit 17 multiplies the maximum transmission bandwidth that can be reserved in the communication network 3 by a percentage G% (where 0 <G <100 (unit:%)). May be calculated as the second bandwidth reservation amount RB2 (t). In this case, (100-G)% of the maximum transmission band that can be reserved by the communication network 3 remains unreserved, so that other data communication using the same communication network 3 can reserve the band. The possibility can be left.

  As a method for determining the ratio G%, a fixed value may be set in advance. Instead, the ratio G% may be determined in inverse proportion to the number of communication links NL that have reserved a bandwidth on the same communication channel. For example, when three communication links have reserved bandwidths on the same communication channel (when NL = 3), the ratio G% is 1/3 and is determined to be approximately 33%. The number of communication links NL that have reserved a band on the same communication channel can be easily grasped by detecting a beacon signal on the communication channel.

  Instead, the ratio G% may be determined in inverse proportion to the number of terminals NT existing on the same communication channel. For example, when five terminals exist on the same communication channel (when NT = 5), the ratio G% is determined to be 1/5 and 20%.

  The second bandwidth reservation amount calculation unit 17 may calculate a predetermined bandwidth amount as the second bandwidth reservation amount RB2 (t). Also in this case, there is a possibility that a transmission band that is not reserved for bandwidth remains, and the possibility that other data communication using the same communication network 3 can reserve the bandwidth can be left.

  After the change of the communication channel, the second bandwidth reservation amount RB2 (t) is set to zero after the time when the remaining amount of data in the transmission data buffer 12 is expected to be zero or a predetermined value close to zero. The reservation amount RB2 (t) is not added.

  The first bandwidth reservation amount RB1 (t) calculated by the first bandwidth reservation amount calculator 14 and the second bandwidth reservation amount RB2 (t) calculated by the second bandwidth reservation amount calculator 16 are respectively bandwidth reservation control. And the bandwidth reservation control unit 18 sets the sum of the first bandwidth reservation amount RB1 (t) and the second bandwidth reservation amount RB2 (t) as the combined bandwidth reservation amount RB3 (t), and the corresponding MAS. A bandwidth reservation of several RM (t) is requested to the wireless communication unit 15.

  A method for obtaining the corresponding MAS number RM (t) from the first bandwidth reservation amount RB1 (t) also when obtaining the corresponding MAS number RM (t) from the combined bandwidth reservation amount RB3 (t) is expressed by the equation (2). In the same manner as described with reference to Equation (5), the synthesized bandwidth reservation amount RB3 (t) is divided by the physical data rate value PDR, multiplied by 256 (the number of MASs in the superframe), and the decimal part is subtracted. Perform round-up processing.

  FIG. 7 shows an example of the temporal change of the bit rate value B (t) of the video data input to the bandwidth reservation apparatus 10 according to the embodiment and the temporal change of the combined bandwidth reservation amount RB3 (t). The combined bandwidth reservation amount RB3 (t) is the sum of the first bandwidth reservation amount RB1 (t) and the second bandwidth reservation amount RB2 (t). In FIG. 7, the vertical axis represents the bit rate value B (t) of the video data and the combined bandwidth reservation amount RB3 (t), and the horizontal axis represents time (time) t.

  Time T1 is the time when the reserved bandwidth is released on the first communication channel, and time T2 is the time when the first bandwidth reservation amount RB1 (t) is secured on the communication network 3 on the second communication channel.

  In FIG. 7, in a period T12 from time T1 to time T2, the reserved transmission band is insufficient with respect to the bit rate value of the video data, which is also referred to as an insufficient amount (“insufficient transmission band amount”). ) Is (B-RB1) = (B-0). A data amount (corresponding to the area of the hatched area in the period from time T1 to time T2 in FIG. 7) obtained by integrating the shortage amount of the transmission band over the period from time T1 to time T2 is the transmission data buffer 12 Is equal to the remaining data amount. The remaining amount of data in the transmission data buffer 12 increases until time T2. DB1 indicates the remaining amount of data in the transmission data buffer 12 at time T2.

  The amount of data stored in the transmission data buffer 12 from time T1 to time T2 is the same as the above-described bandwidth reservation compensation amount C (t). By additionally securing a transmission band corresponding to the band reservation compensation amount C (t) during a period T13 up to time T3, the transmission band is increased and stored in the transmission data buffer 12 from time T1 to time T2. Thus, the remaining data amount can be reduced to zero or a value close to zero at time T3.

式（７）を変形すると、下記の式（８）が得られる。 Even in transmission for reducing the amount of data stored in the transmission data buffer 12, it is necessary to take into account the packet error rate PER and the penalty time PTM. That is, the time T13 depends on the additionally reserved transmission band, that is, the second bandwidth reservation amount RB2 (t), the packet error rate PER, and the penalty time PTM.
If the second bandwidth reservation amount RB2 (t) is constant during the time T13, the following is made between the second bandwidth reservation amount RB2 (t), the time T13, and the bandwidth reservation compensation amount C (t): (7).

When the equation (7) is transformed, the following equation (8) is obtained.

式（８）により、期間Ｔ１３を算出することができる。期間Ｔ１３の算出も、第二帯域予約量算出部１７で行われる。そのため、第二帯域予約量算出部１７は、パケットエラー率ＰＥＲを示す情報を無線通信部１５から受け、ペナルティ時間ＰＴＭを示す情報を記憶部２２から受ける。

The period T13 can be calculated by Expression (8). The calculation of the period T13 is also performed by the second bandwidth reservation amount calculation unit 17. Therefore, the second bandwidth reservation amount calculation unit 17 receives information indicating the packet error rate PER from the wireless communication unit 15 and information indicating the penalty time PTM from the storage unit 22.

  The second bandwidth reservation amount calculation unit 17 recognizes the time T2 based on the notification from the wireless communication unit 15 (notification indicating that the reserved bandwidth has been secured), and measures the period T13 using the clock 19. Then, the addition of the second bandwidth reservation amount RB2 (t) is started at time T2, and the addition of the second bandwidth reservation amount RB2 (t) is ended at time T3 when the period T13 has elapsed from time T2. If the packet error rate PER is zero, the area hatched in the period from time T1 to time T2 is equal to the area hatched in the period from time T2 to time T3 in FIG. Thus, the time T3 is obtained using this relationship.

Further, even if the additional bandwidth reservation by the second bandwidth reservation amount RB2 (t) is not performed until the remaining data amount of the transmission data buffer 12 becomes exactly zero, it is expected to be zero or a predetermined value close to zero. It can be done until the time.
Further, as described above, since it is not necessary to accurately predict the time until the remaining amount of data in the transmission data buffer 12 becomes zero or a predetermined value close to zero, instead of the equation (8), the bandwidth A value obtained by dividing the reservation compensation amount compensation amount C (t) by the second band reservation amount RB2 (t) is a time T13 until the time when the remaining data amount of the transmission data buffer 12 becomes zero or a predetermined value close to zero. Approximate calculation may be performed, and additional reservation with the second bandwidth reservation amount RB2 (t) may be performed only during the time T13.

  FIG. 8 shows the remaining amount of data in the transmission data buffer 12. In FIG. 8, the vertical axis indicates the remaining amount of data (data remaining amount) accumulated in the transmission data buffer 12, and the horizontal axis indicates time. In FIG. 8, the remaining amount of data in the transmission data buffer 12 increases in a period T12 from time T1 to time T2, the remaining amount of data in the transmission data buffer 12 becomes the value DB1 at time T2, and the time from time T2 to time T3. In this example, the remaining data amount of the transmission data buffer 12 decreases during the period T13, and the remaining data amount of the transmission data buffer 12 becomes zero at time T3. As shown in FIG. 8, the increased data remaining amount in the transmission data buffer 12 decreases rapidly according to the transmission band additionally secured as the second bandwidth reservation amount RB2 (t), and becomes 0 at time T3. The tolerance to communication failure is restored to the same level as before the communication channel change.

  According to the first embodiment, even if transmission data is suddenly generated in the communication channel, the second time from when the reserved bandwidth is released in the first communication channel (for example, time T1). Data of transmission data input to the transmission data buffer 12 during a period (for example, period T12) until the time (for example, time T2) when the first bandwidth reservation amount RB1 (t) is secured on the communication network 3 on the communication channel. By additionally reserving the bandwidth corresponding to the transmission bandwidth (for example, the hatched portion of the period T13 in FIG. 7), the remaining amount of data stored in the transmission data buffer 12 can be quickly obtained as shown in FIG. The transmission data buffer 12 is less likely to overflow and stable transmission data transmission is possible.

Embodiment 2. FIG.
FIG. 9 schematically shows a configuration of transmitting apparatus 1 according to Embodiment 2 of the present invention. The transmission device 1 is used in the communication system shown in FIG.
The illustrated transmission apparatus 1 has the same configuration except that the communication channel change execution determination unit 20 and the other communication channel communication checking unit 21 are added to the configuration of FIG. 2 described in the first embodiment. Therefore, the description of the same matters as those described in Embodiment 1 is omitted. The communication channel change execution determination unit 20 forms part of the bandwidth reservation device 10.

  The communication channel change execution determination unit 20 determines whether to change the communication channel used for data transmission based on the amount of data stored in the transmission data buffer 12.

  The other communication channel investigation unit 21 investigates the communication state of communication channels other than the first communication channel used for communication. Specifically, the other communication channel investigation unit 21 sequentially adjusts the frequency to a communication channel other than the first communication channel, investigates the number of MASs already reserved in the communication channel, and newly reserves in the communication channel. Calculate the number of possible MASs.

  The communication channel change request unit 16 determines whether or not the change of the communication channel is appropriate when the change of the communication channel is necessary during the communication on a certain communication channel (first communication channel). This is requested to the channel change execution determination unit 20. The communication channel change request unit 16 is the same as that of the first embodiment, and the communication channel change request output from the communication channel change request unit 16 is received by the communication channel change execution determination unit 20. It may be received as a request for determining whether or not the change is appropriate.

  The communication channel change execution determination unit 20 determines whether or not to change the communication channel in response to the request from the communication channel change request unit 16. As a criterion for this determination, the remaining amount of data stored in the transmission data buffer 12 is used.

  An example of the transition of the remaining data amount of the transmission data buffer 12 when the communication channel is changed is shown in FIG. In FIG. 10, the reserved bandwidth in the first communication channel is released at time T4, the change to the second communication channel is started, and the bandwidth reservation is completed in the second communication channel at time T5. In the example of FIG. 10, the remaining amount of data in the transmission data buffer has increased to DB2 due to the influence of a temporary communication error or the like before time T4. Therefore, communication associated with the communication channel change from time T4 to time T5. Due to an increase in the remaining amount of data in the transmission data buffer due to a lack of bandwidth, the remaining data amount exceeds DBF, which is the maximum data size of the transmission data buffer 12, and a buffer overflow occurs at time T6.

  When a buffer overflow occurs, transmission data to be transmitted to the receiver 2 is lost. When the transmission data is video data, when the transmitted video data is played back, noise or frame loss occurs in the playback video. As a result, the playback video quality is degraded.

Therefore, when data is accumulated in the transmission data buffer 12 during a period T45 from time T4 to time T5, the data amount DB3 is calculated. The calculation of the accumulated data amount DB3 is performed at time T4, the predicted value at time T5 is used, and the accumulated data amount DB3 is also an expected value.
Since the time from time T4 to time T5, that is, the time T45 necessary for changing the communication channel is almost constant, for example, a value obtained by measurement in advance is stored in the storage unit 22, and the storage unit 22 It can be supplied to the communication channel change execution determination unit 20 and used. If the bit rate value B notified from the bit rate notification unit 13 is multiplied by the time T45, the data amount DB3 accumulated in the transmission data buffer 12 during the time T45 can be calculated.

  If the remaining data amount DB2 of the transmission data buffer 12 at time T4 is equal to or less than the value (threshold value) DB4 obtained by subtracting the data amount DB3 from the maximum data size DBF of the transmission data buffer 12, bandwidth reservation is made on the second communication channel. No overflow occurs in the transmission data buffer 12 by the time T5 when is completed.

  Accordingly, when the communication channel change execution determination unit 20 is requested by the communication channel change request unit 16 to determine whether or not the communication channel change is appropriate, the remaining data DB2 of the transmission data buffer 12 is equal to or less than the threshold DB4. If so, the second bandwidth reservation amount calculation unit 17 and the wireless communication unit 15 are requested to change to the second communication channel. The wireless communication unit 15 is not requested to change to the second communication channel.

  If the remaining data DB2 of the transmission data buffer 12 is equal to or less than the threshold DB4 but is close to the threshold DB4, a buffer overflow is likely to occur in the transmission data buffer 12 after time T5. A value (DB4-ΔD) obtained by subtracting the value (ΔD) may be used as a determination reference value, and if the remaining data amount is larger than that, no change may be requested.

  At time T4, the remaining amount of data in the transmission data buffer 12 is equal to or greater than the threshold value DB4 or the determination reference value (DB4-ΔD), and even when the second communication channel is not changed, the first data is received after time T4. If the communication state of the communication channel is improved, the remaining amount of data in the communication data buffer 12 can be expected to decrease. Therefore, for example, after a predetermined time elapses, it is determined again whether or not the change of the communication channel is appropriate, and if the determination result that the change is appropriate is obtained, the change of the communication channel can be performed.

  As described above, when the communication channel change request unit 16 requests to determine whether or not the change of the communication channel is appropriate, the communication channel change execution determination unit 20 determines whether or not to change the communication channel. In addition, by using the remaining amount of data stored in the transmission data buffer 12, when there is a high probability that a buffer overflow will occur, it is possible to suppress the change of the communication channel, and to reduce the quality of transmitted data. Can be suppressed.

  As described above, in the example of FIG. 10, the communication channel change execution determination unit 20 is between the data amount DB2 stored in the transmission data buffer 12 and the bandwidth reservation blank time T45 generated when the communication channel is changed. When the data amount (DB3 + DB2) obtained by adding the transmission data amount DB3 input to the transmission buffer 12 exceeds the maximum accumulated data amount DBF of the transmission data buffer 12, it is determined that the communication channel is to be changed. Determines not to change the communication channel.

  When it is determined whether or not to change the communication channel based on the above determination, information on a bandwidth that can be reserved in the second channel (candidate communication channel after the change) is unnecessary. Accordingly, the supply of information indicating the second channel to the communication channel change execution determination unit 20 can be omitted, and the above determination can be performed before the selection of the second channel.

  Instead, after changing to the second communication channel, the estimated time (the estimated time until buffer stabilization) until the remaining amount of data stored in the transmission data buffer 12 is reduced to 0 is used as a criterion for the above determination. May be used. In this case, when the communication channel change request unit 16 requests the communication channel change execution determination unit 20 to determine whether the change of the communication channel is appropriate, the communication channel after the selected change (destination) (Candidate) and information indicating the amount of bandwidth that can be reserved in the communication channel is notified to the communication channel change execution determination unit 20.

  One of the purposes of temporarily storing transmission data in the transmission data buffer 12 is a speed at which transmission data is input from the data input unit 11 and a speed at which transmission data is transmitted to the communication network 3 by the wireless communication unit 15. The difference is to absorb. For example, when data transmission becomes impossible due to a temporary communication failure on the communication network 3 or the communication speed is reduced, transmission data input from the data input unit 11 is stored without being lost. Data integrity can be maintained. Therefore, the ability to absorb the difference in speed and maintain the integrity of transmission data depends on the free size of the transmission data buffer 12. The empty size of the transmission data buffer 12 is a value obtained by subtracting the remaining data amount of the transmission data buffer 12 from the maximum size of the transmission data buffer 12.

  The state where the remaining amount of data in the transmission data buffer 12 is not 0 is a state where the capacity of the transmission data buffer 12 cannot be utilized to the maximum, and is a state vulnerable to a communication failure. A state in which the remaining data amount of the transmission data buffer 12 is not zero continues for a long time, which means that a state vulnerable to a communication failure continues for a long time and should be avoided as much as possible. Therefore, when the estimated time until the remaining amount of data stored in the transmission data buffer 12 decreases to 0 is long, it can be determined that the communication channel should not be changed.

  When the communication channel change execution determination unit 20 is requested by the communication channel change request unit 16 to determine whether or not the communication channel change is appropriate, the communication channel change execution determination unit 20 can make a reservation with the notified communication channel (candidate). Information on the number of MASs is obtained from the other communication channel survey unit 21. The number of MASs corresponding to the transmission band calculated by the first band reservation amount calculation unit 14 is subtracted from the number of MASs that can be reserved, and the second band reservation amount calculation unit 17 calculates from the remaining number of MASs. The number of MAS corresponding to the transmission band is calculated.

  An example of the transition of the remaining amount of data in the transmission data buffer when the communication channel is changed is shown in FIG. In FIG. 11, time T7 is the time to release the reserved bandwidth on the first communication channel, and time T8 is the time to complete the bandwidth reservation on the second communication channel to be changed (reserving the reserved bandwidth on the second channel). The time T9 is a time when the remaining data amount of the transmission data buffer 12 decreases to 0 after changing to the second communication channel.

Here, the remaining data DB 6 of the transmission data buffer 12 at the time T8 when the band reservation is completed in the second communication channel of the change destination is calculated. This calculation is performed at time T7, and an expected value at time T8 is used. If the bit rate value B (t) is constant during a time T78 from time T7 to time T8, the data amount DB7 accumulated in the transmission data buffer 12 during the time T78 is notified from the bit rate notification unit 13. Can be expressed by the following equation (9).
DB7 = T78 × B (9)
Since the time T78 required for changing the communication channel is almost constant and almost constant, for example, a value obtained by measurement in advance is stored in the storage unit 22 and the communication channel is changed from the storage unit 22. It can be supplied to the execution determination unit 20 and used. By adding the data amount DB7 obtained by Expression (9) and the remaining data amount DB5 of the transmission data buffer 12 at time T7, the remaining data amount DB6 of the transmission data buffer 12 at time T8 can be calculated.

  After changing to the second communication channel, the expected time T89 until the remaining data amount of the transmission data buffer 12 decreases to 0 is calculated using the remaining data amount (DB5 + DB7) of the transmission data buffer at time T8. It can be obtained by an expression similar to Expression (8), that is, an expression in which C (t) in Expression (8) is replaced with (DB5 + DB7) and T13 is replaced with T89. If the packet error rate PER is zero, T89 can be obtained by dividing (DB5 + DB7) by the second bandwidth reservation amount RB2 (t).

  The communication channel change execution determination unit 20 calculates the second bandwidth reservation amount if the estimated time T89 until the remaining data amount of the transmission data buffer 12 calculated as described above is within a predetermined time. Unit 17 and wireless communication unit 15 are requested to change to the second communication channel, and if the predetermined time is exceeded, second bandwidth reservation amount calculation unit 17 and wireless communication unit 15 Does not require switching to a communication channel.

  In the above example, the time until the remaining amount of data in the transmission data buffer 12 becomes 0 is defined as the buffer stabilization time, and it is determined whether the buffer stabilization time is within a predetermined time. , Instead of the time until “0” is reached, the time until it decreases to a predetermined value close to 0 or less may be used as the buffer stabilization time.

  In addition, instead of the above-mentioned “expression similar to expression (8)”, the value obtained by dividing (DB5 + DB7) by the second bandwidth reservation amount RB2 (t) is zero or zero in the transmission data buffer 12. Approximate calculation with time T89 until the time when it reaches a predetermined value close to, and whether or not the time T89 exceeds a predetermined value is used as a criterion. good.

  According to the transmission apparatus according to the second embodiment, even when there is a communication channel change request from the communication channel change request unit 16, the probability of buffer overflow occurring due to the state of the remaining data in the transmission data buffer 12 Is high, the change of the communication channel can be suppressed, and the quality deterioration of the transmitted data can be suppressed.

  Further, according to the second embodiment, when a change in the remaining amount of data in the transmission data buffer is predicted when the communication channel is changed, and there is a possibility that the transmission data buffer overflows, the communication channel is changed. There is an effect that the data can be suppressed and stable data transmission can be performed.

Although the embodiment of the present invention has been described as the bandwidth reservation device, the bandwidth reservation method implemented by the bandwidth reservation device, the communication device including the bandwidth reservation device, and the communication system including the communication device are also described. It forms part of the invention.
The bandwidth reservation apparatus and the bandwidth reservation method according to Embodiments 1 and 2 of the present invention are input at a constant bit rate value such as video data and audio data via a communication network that performs bandwidth reservation type media access control. The present invention can be applied to a communication system that transmits video data to be transmitted from a transmission device to a reception device, such as a wireless video / audio transmission system.

  DESCRIPTION OF SYMBOLS 1 Transmission apparatus, 2 Reception apparatus, 3 Communication network, 4 Content supply source, 10 Band reservation apparatus, 11 Data input part, 12 Transmission data buffer, 13 Bit rate value notification part, 14 1st band reservation amount calculation part, 15 Wireless Communication unit, 16 communication channel change request unit, 17 second bandwidth reservation amount calculation unit, 18 band reservation control unit, 19 clock, 20 communication channel change execution determination unit, 21 other communication channel survey unit, 22 storage unit.

Claims (12)

A transmission band reservation type communication system comprising a transmission data buffer for temporarily storing the transmission data during a period from transmission data input to transmission of the transmission data to a communication network, and a plurality of transmission data buffers on the communication network In the communication channel selected from among the communication channels, a bandwidth reservation device of a communication device for reserving a transmission band and transmitting data stored in the transmission data buffer in the reserved transmission band,
A bit rate value notifying unit for detecting and notifying a bit rate value of the transmission data;
From the bit rate value of the transmission data, a first bandwidth reservation amount calculation unit that calculates a bandwidth amount necessary for transmission in the communication network as a first bandwidth reservation amount;
When the communication channel used for transmission of the transmission data is changed, the bandwidth reservation blank time which is the time until the reserved bandwidth acquired in the communication channel before the change is released and the bandwidth is reserved in the channel after the change A second bandwidth reservation amount calculation unit for calculating an additional bandwidth for reducing the data accumulated in the transmission data buffer by transmission on the changed communication channel as a second bandwidth reservation amount;
During the time when the communication channel for transmitting the transmission data is changed, the reserved bandwidth is released,
A bandwidth reservation control unit that reserves a combined bandwidth reservation amount of the first bandwidth reservation amount and the second bandwidth reservation amount in a time for transmitting transmission data on the communication channel after the change ,
The second bandwidth reservation amount calculation unit,
A bit rate of the transmission data or a value obtained by integrating the first bandwidth reservation amount over the bandwidth reservation blank time is calculated as a data amount accumulated in the transmission data buffer in the bandwidth reservation blank time,
A value obtained by dividing the data amount by the second bandwidth reservation amount is calculated as a time until the remaining data amount of the transmission data buffer becomes zero or a predetermined value close to zero,
The bandwidth reservation apparatus, wherein the second bandwidth reservation amount is added for the calculated time . Based on the amount of data accumulated in the transmission data buffer, to claim 1, further comprising a communication channel change execution determination unit that determines whether to perform the change of the communication channel for transmitting transmission data The bandwidth reservation device described. The communication channel change execution determination unit has a data amount obtained by adding a data amount accumulated in the transmission data buffer and a transmission data amount expected to be input to the transmission data buffer during the bandwidth reservation blank time. , if the does not exceed the maximum amount of data stored in the transmission data buffer, it is determined that carrying out the change of the communication channel, if more than, claim 2, wherein the determining not to implement the change of the communication channel Bandwidth reservation device described in 1. The communication channel change execution determination unit includes a data amount obtained by adding a data amount accumulated in the transmission data buffer and a transmission data amount expected to be input to the transmission data buffer during the bandwidth reservation blank time; Based on the second bandwidth reservation amount that is expected to be secured after the change of the communication channel, the time until the remaining data amount of the transmission data buffer is expected to decrease to zero or a predetermined value close to zero, 3. The bandwidth reservation apparatus according to claim 2 , wherein when the predetermined value is not exceeded, it is determined that the communication channel is changed, and when the predetermined value is exceeded, it is determined that the communication channel is not changed. The communication channel change execution determination unit adds a data amount obtained by adding a data amount accumulated in the transmission data buffer and a transmission data amount expected to be input to the transmission data buffer during the bandwidth reservation blank time. When the value divided by the second bandwidth reservation amount that is expected to be secured after the communication channel is changed does not exceed a predetermined value, it is determined that the communication channel is changed. 3. The bandwidth reservation apparatus according to claim 2 , wherein it is determined not to change the channel. A transmission band reservation type communication system comprising a transmission data buffer for temporarily storing the transmission data during a period from transmission data input to transmission of the transmission data to a communication network, and a plurality of transmission data buffers on the communication network A bandwidth reservation method in a communication device for reserving a transmission band in a communication channel selected from among the communication channels and transmitting data stored in the transmission data buffer in the reserved transmission band,
A bit rate value notification step of detecting and notifying a bit rate value of the transmission data;
A first bandwidth reservation amount calculation step of calculating a bandwidth amount necessary for transmission in the communication network as a first bandwidth reservation amount from the bit rate value of the transmission data;
When the communication channel used for transmission of the transmission data is changed, the bandwidth reservation blank time which is the time until the reserved bandwidth acquired in the communication channel before the change is released and the bandwidth is reserved in the channel after the change A second bandwidth reservation amount calculating step for calculating, as a second bandwidth reservation amount, an additional bandwidth for reducing the data accumulated in the transmission data buffer by transmission on the changed communication channel;
The reserved bandwidth is released during the time when the communication channel for transmitting the transmission data is changed, and the first bandwidth reservation amount and the second bandwidth reservation amount are set during the time when the transmission data is transmitted on the changed communication channel. and a bandwidth reservation control step of reserving a synthetic bandwidth reservation amount and,
The second bandwidth reservation amount calculating step includes:
A bit rate of the transmission data or a value obtained by integrating the first bandwidth reservation amount over the bandwidth reservation blank time is calculated as a data amount accumulated in the transmission data buffer in the bandwidth reservation blank time,
A value obtained by dividing the data amount by the second bandwidth reservation amount is calculated as a time until the remaining data amount of the transmission data buffer becomes zero or a predetermined value close to zero,
The bandwidth reservation method, wherein the second bandwidth reservation amount is added only for the calculated time . On the basis of the amount of data accumulated in the transmission data buffer, to claim 6, further comprising if the communication channel change execution determination step of determining whether to implement the change in the communication channel for transmitting transmission data The bandwidth reservation method described. In the communication channel change execution determination step, the data amount obtained by adding the amount of data stored in the transmission data buffer and the amount of transmission data expected to be input to the transmission data buffer during the bandwidth reservation blank time is , does not exceed the maximum amount of data stored in the transmission data buffer, it is determined that carrying out the change of the communication channel, if more than, claim 7, characterized in that to determine not to implement the change of the communication channel Bandwidth reservation method described in 1. The communication channel change execution determining step includes a data amount obtained by adding a data amount accumulated in the transmission data buffer and a transmission data amount expected to be input to the transmission data buffer during the bandwidth reservation blank time; Based on the second bandwidth reservation amount that is expected to be secured after the change of the communication channel, the time until the remaining data amount of the transmission data buffer is expected to decrease to zero or a predetermined value close to zero, 8. The bandwidth reservation method according to claim 7 , wherein when the predetermined value is not exceeded, it is determined that the communication channel is changed, and when the predetermined value is exceeded, it is determined that the communication channel is not changed. In the communication channel change execution determination step, a data amount obtained by adding a data amount accumulated in the transmission data buffer and a transmission data amount expected to be input to the transmission data buffer during the bandwidth reservation blank time is obtained. When the value divided by the second bandwidth reservation amount that is expected to be secured after the communication channel is changed does not exceed a predetermined value, it is determined that the communication channel is changed. The bandwidth reservation method according to claim 7 , wherein it is determined that the channel change is not performed. The bandwidth reservation apparatus according to any one of claims 1 to 5 ,
And a wireless communication unit that transmits the transmission data according to a bandwidth reservation amount requested by the bandwidth reservation control unit. A communication device according to claim 11 ;
An access control means provided in the communication network.

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