JP4790663B2 - Relay device - Google Patents

Description

  The present invention relates to a relay device that relays data and a relay method in the relay device.

  Typical wireless network systems including wireless sections include a wireless local area network (LAN) (IEEE 802.11) and a cellular system (for example, 3GPP: Third Generation Partnership Project).

  FIG. 20 is a diagram illustrating a configuration example of a wireless LAN. The wireless LAN includes, for example, a media server, a wireless network gateway connected to the media server, a plurality of access points connected to the wireless network gateway, and a plurality of terminals existing in the wireless service area of the access point.

FIG. 21 is a diagram illustrating a configuration example of a 3GPP (cellular) system. The 3GPP system is, for example, an xGSN (serving / gateway GPRS Support Node connected to the Internet).
), A plurality of RNCs (Radio Network Controllers) connected to the xGSN, a plurality of Node-Bs (BTS) connected to the RNC, and a plurality of terminals existing in the wireless service area of the Node-B.

  When communicating in a wireless communication environment such as a wireless LAN or a 3GPP system, congestion due to the concentration effect tends to occur in a wireless LAN, for example, in a wireless network gateway, and in a cellular system, in an xGSN or RNC. In other words, the wireless network gateway generally has a tree configuration in which a plurality of access points, a plurality of RNCs in the xGSN, and a plurality of BTSs (Base Transceiver Stations) in the RNC are arranged. For this reason, the data is concentrated in the radio network gateway, xGSN and RNC. Moreover, since the wireless access network has a narrow bandwidth, it is in a state where it is more likely to be congested.

In such a situation, for example, in the cellular system, band control is performed by the RNC. For example, real-time data (for example, moving image streaming transfer data) and non-real-time data (for example, text data) are divided into classes, and transmission priorities are assigned. In the wireless LAN, transmission priority is set according to the data type in EDCA (Enhanced Distributed Channel Access) as defined in IEEE802.11e. These are generally called QoS (Quality of Service) control.

Through this QoS control, real-time data is given a high transmission priority and is controlled to ensure its quality.
JP-A-11-98128 JP 2000-197104 A

QoS control as described above is very convenient for real-time data. In general, it is important that all non-real-time data arrives at the receiving side, and the trouble caused by the arrival time of non-real-time data being delayed is not a problem. Furthermore, since the restrictions on the arrival time of the non-real time data are looser than those of the real time data, if the non-real time data is discarded in the middle of transmission, it is sufficient to be rescued by retransmitting the data. For this reason, control is performed to postpone transmission for non-real-time data. Conversely, real-time data has stronger time restrictions on arrival time than non-real-time data. Further, when non-real time data is discarded in the middle of transmission, a case may occur where the arrival time on the receiving side, that is, the reproduction time is not in time. Therefore, mid-term discard of real-time data affects the quality of data reproduction. In addition, when UDP (User Datagram Protocol) is applied as a communication protocol for real-time data, data is not retransmitted, and there is a concern about the effect on the quality of reproduced data due to mid-term discard of real-time data. .

  QoS control as described above is not particularly problematic when the amount of real-time data is smaller than the total traffic of real-time and non-real-time data. However, in recent years, the distribution of real-time data has increased rapidly, and the ratio of the amount of real-time data to the total traffic has increased. For example, conventionally, most of the data related to a Web page transferred when accessing a Web site is occupied by non-real-time data such as text data and image data. In recent years, stream-type advertisements are often embedded in Web pages, and video distribution such as Web news is often performed from Web sites. Such stream-type advertisements and video-delivered data are real-time data.

When the occupation rate of the real-time data occupies most of the total traffic, priority control between the real-time data significantly occurs. In general, the boundary between UDP being a real-time system and TCP (Transmission Control Protocol) being a non-real-time system is not clear, and much of the data to be handled is being required to be real-time.

  Also, prioritizing real-time data is very inconvenient for traffic that takes the form of general data downloads. For example, the priority delay and priority discard of non-real-time data appear as throughput that does not increase at all. In other words, the occupation of the transmission band by the real-time data generally takes a long time, so that the influence on the normal non-real-time service is significant. For example, TCP generally reduces its transmission rate to half by discarding data (TCP reno method). This is a control that assumes temporary congestion. For this reason, in the case of congestion that continues for a long time, the usable bandwidth is extremely reduced. Contrary to such a situation, the occurrence of an additional connection for real-time data further reduces the bandwidth of non-real-time data. Even a non-real-time service with loose arrival time restrictions is very uncomfortable for the user.

  Furthermore, the recent increase in real-time data, particularly broadcast-type data, has spurred the above-described problem of bandwidth reduction of non-real-time data. This is because advertisement-type traffic and unidirectional traffic do not have a feedback route and cannot be controlled according to the circumstances of a specific network.

  By the way, unlike the case described above, a problem occurs even when the real-time traffic amount does not occupy the entire transmission band.

  FIG. 22 is a diagram illustrating an example of occurrence of stagnation due to synchronization of transmission periods of streams in a relay apparatus (access point, RNC, or the like). It is assumed that streaming data 1 to 9 and ac are flowing to a plurality of terminals # 1 to # 6, respectively. Since the streaming data is asynchronous, transmission synchronization between the streaming data can occur. Even if the total amount of streaming data occupies half of the transmittable amount (transmission bandwidth) in a certain period of time, when the transmission timing of all streaming is synchronized at a specific time, it occupies the internal buffer, Data may accumulate.

  It is an object of the present invention to provide a relay device that can suppress delay of non-real time data when real-time data and non-real time data coexist.

  The present invention employs the following means in order to solve the above problems.

That is, the present invention
A receiving unit for receiving real-time data and non-real-time data;
A storage unit for storing real-time data and non-real-time data received by the receiving unit;
Percentage of transmission bandwidth of real-time data relative to the maximum transmission bandwidth or transmission bandwidth of real-time data and non-real-time data to be transmitted, or real-time data and non-real-time data stored in the storage unit A measurement unit that measures the proportion of real-time data,
A determination unit that determines a discard rate of real-time data based on the ratio;
Based on the discard rate, a discard unit that discards a part of real-time data to be transmitted without transmitting,
A transmission unit that transmits non-real-time data to be transmitted and real-time data that has not been discarded by the discard unit among real-time data to be transmitted;
Is used.

Further, the present invention receives real-time data and non-real-time data,
Stores received real-time data and non-real-time data,
Percentage of transmission bandwidth of real-time data relative to the maximum transmission bandwidth or transmission bandwidth of real-time data and non-real-time data to be transmitted, or real-time data relative to stored real-time data and non-real-time data Measure the proportion of
Determine the discard rate of real-time data based on the ratio,
Based on the discard rate, discard part of the real-time data to be transmitted without transmitting,
Transmitting non-real-time data to be transmitted and real-time data that has not been discarded by the discarding unit among real-time data to be transmitted;
A relay method in the relay device is used.

  ADVANTAGE OF THE INVENTION According to this invention, the relay apparatus which can suppress the delay of non-real-time data in the case where real-time data and non-real-time data coexist can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration of the embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.

[Embodiment 1]
<Overview>
For example, in the network configuration as shown in FIG. 20 or FIG. 21, when data is transmitted to the wireless terminal side, traffic concentration occurs in the wireless network gateway or access point that relays the data, or in the xGSN or RNC Actively discards less important data among real-time data according to the traffic situation. The less important data is, for example, a non-reference picture in MPEG, and background noise data in audio.

  FIG. 1 is a diagram showing a network configuration showing an embodiment of the present invention. This network includes a receiving device 102, a relay device 104 (a device to which the present invention is applied), and a transmitting device 106. Note that there may be a plurality of receiving apparatuses 102 (# 0 to #n are illustrated in FIG. 1). A section between each receiving apparatus 102 and the relay apparatus 104 is referred to as section A. A section between the relay device 104 and the transmission device 106 is referred to as a section B. In the present embodiment, when the transmission rate of the section A is lower than the transmission speed of the section B, the delay of the non-real time data is suppressed and is particularly effective (however, the application is not limited to this). Moreover, there is no restriction | limiting about the communication system of the area A and the area B. FIG. In other words, either a wired network or a wireless network may be used. However, since wireless communication can be considered as a communication method in which the transmission speed of the section A is likely to be low, the delay of non-real-time data is suppressed when applied when the section B is a wired network and the section A is a wireless network. And good effects can be obtained.

  On the contrary, it can be applied to the case where the transmission rate of the section B is lower than that of the section A. For example, there is a case where each receiving apparatus 102 illustrated in FIG. 1 has a data transmission function, and even if the transmission speed of each receiving apparatus 102 is low, the sum thereof has a wider band than section B. Note that the network configuration shown in FIG. 1 is an example, and there may be two or more transmission apparatuses 106. There may be one or more other relay devices between the transmission device 106 and the relay device 104.

  The transmission device 106 is, for example, a server or a media server illustrated in FIGS. 20 and 21, and the reception device 102 is, for example, an access point, a terminal, an xGSN, a Node-B, illustrated in FIGS. The relay device is an RNC, and is, for example, a radio network gateway, an access point, xGSN, RNC, or Node-B shown in FIGS.

  Here, a case is considered where the transmission speed (transmission band) of the section A is lower (smaller) than that of the section B. Specifically, the network communication capability in the section A, an error in the case where a part or all of the section A is configured with a wireless link, and the like can be considered. In this case, traffic concentration is likely to occur in the relay device 104.

  The relay device 104 receives the real-time data and real-time data from the transmission device 106 by the reception unit and temporarily stores them in a storage device (storage unit: for example, a buffer memory). The transmission unit of the relay device 104 stores the data Data to be transferred is read from the device and transferred to the receiving device 102 that is the destination of the read data. It is not an essential requirement of the present invention that real-time data and non-real-time data received by the relay device 104 are transmitted from the same transmission device 106. The present invention can be applied even when the relay device 104 receives real-time data and non-real-time data from a plurality of transmission devices 106.

  Regarding the discarding of data for securing the transmission band, the discard amount of the less important data among the real time data is determined using the following method, and the less important real time data is discarded.

(1) The ratio of the sum of the transmission band of real-time data and the transmission band of non-real-time data to the maximum transmission band of the relay device 104 is obtained. The ratio of the free bandwidth to the maximum transmission bandwidth of the relay device 104 may be obtained. The maximum transmission band is the maximum transmission band that can be transmitted by the relay apparatus. The transmission band is obtained from the amount of data transmitted per predetermined time.

  (2) Subsequently, the data discard amount is determined based on the ratio of the transmission band of the real-time data to the sum of the transmission band of the real-time data and the transmission band of the non-real-time data (transmission band occupation ratio).

  (3) Discard less important data in real-time data.

  Here, when the real-time data includes audio data, data handling only background noise information in the audio data can be discarded. The audio data is generated with a period of 20 ms, for example. In this case, even if the 20 ms portion is temporarily lost, the service recipient rarely feels quality degradation. Here, there is an instantaneous interruption time as a performance index of handover represented as one of the functions of the wireless network. One guideline of the allowable instantaneous interruption time is 250 ms or less. Therefore, in discarding the audio data, it is considered that the maximum is within the allowable range if it is 250 ms or less.

  In addition, when the real-time data includes video data and the video data is encoded (for example, MPEG data), the encoded video data is basically used to increase the encoding efficiency. Reference picture data, non-reference picture data based on motion information for the reference picture, and control data. That is, the transmission data amount is compressed by transmitting the reference picture and the non-reference picture without transmitting all the pictures (in addition, the compression process is performed by the quantization parameter at the time of encoding). ). Important data in such video data is reference pictures and control data. That is, the loss of the reference picture and control data has a significant effect on video reproduction. On the other hand, loss of non-reference pictures does not have a significant effect. Such non-reference picture data is discarded as data of low importance.

  Real-time data always occupies a certain bandwidth. Therefore, with the increase of multimedia services in the future, the opportunity to compress the bandwidth will increase. This means that the bandwidth that can be processed by non-real-time data is reduced. Based on the fairness of the network, it is based on the idea that when the bandwidth is tight, even if it is real-time data, the bandwidth is provided as much as possible. This process may not be performed when there is sufficient free space in the storage device (buffer memory). This is because when there is a sufficient free area, there is little possibility of congestion, and there is no need to discard data in order to secure bandwidth and buffer capacity.

  FIG. 2 is a diagram illustrating an example of the occupied state of the transmission band of real-time data and non-real-time data with respect to the maximum transmission band of the relay device. 2 includes a transmission band for real-time data and a transmission band for non-real-time data. The example of FIG. 2 shows an example of the occupied state 11 of the transmission band with a large free band and the occupied state 12 of the transmission band with a small free band. In the case of the occupied state 11 of the transmission band having a large free band, there is no possibility of congestion and there is little need to discard data in order to secure the band. On the other hand, in the case of the occupied state 12 of the transmission band with a small free band, there is a possibility that congestion may occur. Therefore, it is necessary to perform processing for discarding data and securing the band.

FIGS. 3 and 4 are diagrams showing examples of the amount of real-time data discarded when the transmission band occupation state is the transmission band occupation state 12 of FIG. FIG. 3 shows a case where the ratio of real-time data to non-real-time data is large. FIG. 4 shows a case where the ratio of real-time data to the non-real-time data is small. As shown in FIG. 3, when the ratio of real-time data is large, data to be discarded is determined from data of low importance among real-time data. Since the ratio of real-time data to non-real-time data is large, the amount of data discarded increases both absolutely and relatively. On the other hand, as shown in FIG. 4, even when the ratio of the real-time data to the non-real-time data is small, similarly, the less important data among the real-time data is discarded. However, since the ratio of the real-time data to the non-real-time data is small, the amount of discard is absolutely and relatively small.

  FIG. 5 is a diagram showing discard data in the importance / low data. The discard data (data to be discarded) is selected from the importance / low data of the real-time data. There are two methods of data disposal: a method of discarding data continuously based on the amount of data determined based on a fixed amount of data, and a method of discarding data determined at a fixed cycle. A method of determining a period for discarding based on the above and intermittently performing the discarding process can be considered.

FIG. 6 is a diagram illustrating an example in which the discard process is intermittently performed. When the amount of data to be discarded is calculated, the data to be discarded is selected and discarded from a column of data blocks (called streams) that share the same source and destination on the time axis. (Intermittent disposal). In the example of FIG. 6, data is discarded every four blocks.

  FIG. 7 is a diagram illustrating an example of intermittent discard when there are a plurality of streams. The amount of data discarded for each stream is determined so that the data discarded for a specific stream is not biased. Similarly to the example of FIG. 6, in each stream, data to be discarded is selected and discarded.

  FIG. 8 is a diagram illustrating an example of the relationship between the discard amount calculation period and the data discard period. Data is discarded only during a specific data discard period in the discard amount calculation cycle. The calculation of the data discard period may be determined based on, for example, a predetermined system discard rate (ratio of the discard amount with respect to the maximum transmission bandwidth). In this case, when the discard amount is determined and the system discard rate is determined, the data discard period is also determined. When the data discard period is longer than the discard amount calculation cycle, the system discard rate is increased when priority is given to the discard amount, and the discard amount is decreased when priority is given to the system discard rate. On the contrary, a certain discard period may be determined in advance, and the discard amount may be averaged within the discard period.

<Details>
<Network configuration>
FIG. 9 is a diagram showing a configuration example (embodiment) of a network system which is one of the embodiments of the present invention. In FIG. 9, the network system includes a relay device 104, an AP (Access Point) 202 connected to the relay device 104, and a terminal 204.

  Here, it is assumed that the wireless network is applied, and an example in which a wireless LAN is targeted is shown. As a configuration of the wireless LAN, a plurality of access points (AP, Access Point) and a relay device 104 that controls the access points are used. Wireless access is made between the AP 202 and the terminal 204. Data for the terminal 204 is transmitted from the relay device 104 to the AP 202 having control of the terminal 204.

  FIG. 10 is a basic block diagram of the relay apparatus. The relay device 104 includes a reception unit 1002, a data type determination unit 1004, a data storage unit 1006, a transmission schedule unit 1008, a transmission unit 1010, a discard determination unit 1020, and an occupation rate determination unit 1022.

The receiving unit 1002 receives data (real-time data and non-real-time data) from the network. The receiving unit 1002 converts the received data into the data type determining unit 100.
4 to send.

  The data type determination unit 1004 determines the type of received data, that is, whether it is a real-time data type or a non-real-time data type. Judgment of whether or not. The data identification determination unit 1004 transmits the received data to the data storage unit 1006 together with the data type.

  As a method for determining whether the data is real-time data or non-real-time data, for example, when the data unit to be received is an IP packet, the upper layer header is checked. When the upper layer is TCP or UDP, it can be determined which data type is based on the TCP or UDP port number. For example, non-real-time data can be used for TCP, and real-time data can be used for UDP.

  Furthermore, regarding the importance of the real-time data, for example, an RTP (Real-time Transport Protocol) packet positioned at the upper level of the UDP packet is included in the NAL packet (in the case of H.264 / AVC) header at the higher level. It can be identified by recognizing with an identifier indicating the existing importance. The determination of the data type and the determination of the importance are not limited to these, and various methods can be used.

  The data storage unit 1006 stores data received from the data identification determination unit 1004. The stored data is transmitted to the transmission schedule unit 1008 at the time of transmission together with the data type. Further, when the discard determination unit 1020 uses the buffer occupancy rate in the data storage unit 1006 at the time of discard, the data storage unit 1006 can provide this information to the discard determination unit 1020. The buffer occupancy is a ratio of the data amount of real-time data and non-real-time data stored in the data storage unit 1006 to the data amount (total buffer capacity) that can be stored in the data storage unit 1006.

  The transmission schedule unit 1008 reads the transmission data from the data storage unit 1006 according to the transmission priority order, and transfers the data to the transmission unit 1010. The transmission schedule unit 1008 receives data discard information from the discard determination unit 1020. If the received data is data to be discarded based on the data discard information, the transmission schedule unit 1008 discards this data. The transmission schedule unit 1008 allocates the bandwidth that can be transmitted by discarding the data to the non-real-time data, receives the non-real-time data from the data storage unit 1006, and transmits it to the transmission unit 1010.

  The transmission schedule unit 1008 recognizes real-time data for each destination and for each session (it can be recognized by a combination of an IP address and a TCP / UDP port number, but is not limited thereto). The target data may be discarded at regular intervals according to the amount of real-time data discarded. In this case, the transmission schedule unit 1008 can perform an average discard for each data stream, and can perform a known intermittent discard process for data of low importance in a video stream.

  The transmission schedule unit 1008 has a counter that determines the timing of data discard for each real-time data stream when performing intermittent discard processing, and controls the length of the counter that circulates based on the determined discard amount. The data can also be discarded at every counter cycle. The discard amount is determined by the discard determination unit 1020, and the transmission schedule unit 1008 acquires the data discard information from the discard determination unit 1020.

The occupancy rate determination unit 1022 receives transmission information for each type of data (information on real-time data (importance / high, importance / low) transmission band, non-real-time data transmission band) from the transmission schedule unit 1008. get. The occupancy rate determination unit 1022 determines, based on the transmission information for each data type, the transmission band occupancy rate (the maximum transmission band of the relay device or the transmission band of real-time data and non-real-time data to be transmitted) The ratio of the transmission bandwidth of The occupancy rate determination unit 1022 calculates the transmission band occupancy rate at a predetermined cycle (discard amount calculation cycle) and notifies the discard determination unit 1020 of it.

  The discard determination unit 1020 determines the discard rate, the discard amount, and the discard target data from the transmission band occupation rate received from the occupation rate determination unit 1022. Data to be discarded is data of low importance among real-time data. The discard determination unit 1020 notifies the transmission schedule unit 1008 of data discard information (discard rate, discard amount, discard target data). The data to be discarded may be determined based on information described in the data received by the receiving unit 1002.

  Also, the discard determination unit 1020 determines the discard rate, the discard amount, and the discard target data only when the ratio of the transmission band of the real-time data and the non-real-time data to the maximum transmission band in the transmission schedule unit 1008 is within a specific range. (Discarding determination processing may be performed). For example, in the information acquired from the occupation rate determination unit 1022, when the transmission band occupies 80% to 100% of the maximum transmission band, the discard determination unit 1020 may perform the discard determination process. Alternatively, the buffer occupancy rate in the data storage unit 1006 may be used as a criterion for the discard determination unit 1020 to perform the discard determination process. In this case, the discard determination unit 1020 acquires the buffer occupancy rate from the data storage unit 1006.

  The transmission unit 1010 transmits the data transferred from the transmission schedule unit 1008 to the destination. In addition, when there are a plurality of APs 202, the transmission unit 1010 performs distribution to the destination AP.

<Operation example>
FIG. 11 is a diagram illustrating an example of a basic processing flow of the relay apparatus.

  The transmission schedule unit 1008 of the relay device 104 reads the transmission data from the data storage unit 1006 according to the transmission priority order, and transfers the data to the transmission unit 1010. In normal control, transmission of real-time data is prioritized during transmission.

  The occupation rate determination unit 1022 of the relay device 104 determines whether or not the bandwidth monitoring cycle (discard amount calculation cycle) has expired (S1004). This is because data is discarded at regular intervals. Accordingly, the next data discarding process is not performed before a certain period expires.

  When the bandwidth monitoring cycle expires (S1004; YES), the relay device 104 enters the next bandwidth monitoring cycle. The occupation rate determination unit 1022 of the relay device 104 determines whether or not the status of the transmission band of the real-time data and the non-real-time data is within the discard control condition (S1006).

Specifically, the occupancy rate determination unit 1022 of the relay apparatus 104 obtains transmission information for each data type from the transmission schedule unit 1008, and the transmission bandwidth of real-time data and non-real-time data is greater than the maximum transmission bandwidth. It is determined whether or not the occupation ratio is equal to or greater than a predetermined value. The occupation rate determination unit 1022 of the relay device 104 satisfies the discard control condition (discard control is necessary) when the ratio of the transmission band of real-time data and non-real-time data to the maximum transmission band is equal to or greater than a predetermined value. (S1006; YES). This is because when the ratio of the transmission bandwidth of real-time data and non-real-time data to the maximum transmission bandwidth is greater than or equal to a predetermined value, congestion may occur, and data discard control must be performed. . However, the configuration may be such that data discard control is performed regardless of the ratio of the transmission bandwidth of real-time data and non-real-time data to the maximum transmission bandwidth.

  When it is determined that the ratio of the transmission bandwidth of the real-time data and the non-real-time data to the maximum transmission bandwidth is within the discard control condition (S1006; YES), the occupation rate determination unit 1022 of the relay device 104 A transmission band occupation ratio is calculated (S1008).

The occupancy rate determination unit 1022 of the relay device 104 obtains the transmission band of real-time data, the transmission band of non-real-time data, the data of the maximum transmission band, etc. from the transmission schedule unit 1008. The transmission bandwidth occupancy (A) is calculated.

In Expression (1), the transmission band of the real-time data with respect to the maximum transmission band of the relay device 104 is defined as a transmission band occupation ratio (A).

  The occupation rate determination unit 1022 of the relay device 104 determines whether or not the real-time data needs to be discarded (S1010). The occupancy rate determination unit 1022 of the relay device 104 determines that it is not necessary to discard the real-time data when the transmission bandwidth occupancy rate (A) of the real-time data does not exceed a predetermined value (S1010; NO). This is because the transmission band for non-real-time data is considered to be sufficiently secured because the transmission band for real-time data is small. Further, the occupancy rate determination unit 1022 of the relay device 104 determines that the real-time data needs to be discarded when the transmission bandwidth occupancy rate (A) of the real-time data exceeds a predetermined value, and determines the discard. The data discard determination process is instructed to the unit 1020 (S1010; YES).

  When the transmission bandwidth occupancy rate (A) of real-time data exceeds a predetermined value (S1010; YES), the discard determination unit 1020 of the relay device 104 calculates the discard amount and the discard rate of real-time data (S1012). ).

The discard determination unit 1020 of the relay device 104 determines the discard rate (B) and the discard amount (C) of real-time data according to the following formula.

Equation (2) represents the discard rate (B), and is obtained as a power of the transmission band occupation rate (A) and an exponent n. Expression (3) represents the discard amount (C), and is obtained by multiplying the transmission amount of data with low importance by the discard rate (B). The discard amount (C) is a discard amount of data with low importance.

  The index n in equation (2) is a coefficient that suppresses the discard rate (B). By increasing the coefficient n, the discard rate (B) can be further suppressed when the transmission band occupation rate (A) of real-time data is small. By manipulating the discard rate by the coefficient n, the size of the transmission band can be kept within a predetermined range.

  FIG. 12 is a diagram illustrating a table of the relationship between the coefficient n in Expression (2) and the discard rate (B). For example, when the coefficient n is 4, when the value of the transmission bandwidth occupancy rate (A) is 30%, the discard rate is 0.81%, and real-time data with low importance is hardly discarded. On the other hand, when the value of the transmission bandwidth occupancy rate (A) is 90%, the discard rate is 65.91%, and many real-time data with low importance are discarded. Thus, by setting the value obtained by raising the transmission band occupancy rate (A) to the power of the coefficient n as the discard rate (B), the discard rate can be further suppressed when the transmission band occupancy rate (A) is small. . The coefficient n can be a constant or a value that depends on the transmission bandwidth occupancy rate (A) (for example, a large value is taken when A is small and a small value is taken when A is large).

  Further, the discard amount (C) may be determined based on a transmission band of real-time data or a transmission band of highly important data among real-time data.

The discard determining unit 1020 of the relay apparatus 104 calculates a discard period. The discard determination unit 1020 determines the discard period (I) in the discard calculation cycle from the discard amount (C) and the maximum transmission band (G). When congestion occurs, the transmission band (transmission rate) of the relay device 104 can be regarded as the maximum transmission band (maximum transmission rate). Therefore, the discard period (I) is given using the following equation (4).

  Here, the system discard rate (H) is set in advance. The system discard rate (H) is a discard rate with respect to the maximum transmission band defined for the entire relay apparatus 104 regardless of the discard rate (B) in the equation (2). Therefore, the denominator of equation (4) means the amount discarded per unit time. Therefore, the discard period (I) is obtained as a value obtained by dividing the discard amount (C) by the data amount discarded per unit time.

Here, when the discard period (I) exceeds the maximum discard period (discard amount calculation period), the discard period (I) is set as the maximum discard period (J). At this time, the system discard rate (H) is obtained as in the following equation (5).

  The discard determination unit 1020 of the relay apparatus 104 determines data to be discarded based on the calculated discard amount, and notifies the transmission schedule unit 1008 of the data. The transmission schedule unit 1008 may determine data to be discarded based on the discard amount calculated by the discard determination unit 1020. The relay device 104 intermittently discards the data determined to be discarded from the data received by the transmission schedule unit 1008 from the data storage unit 1006 (S1014). When there are a plurality of streams, the amount of data to be discarded is determined for each stream so that the data to be discarded in a specific stream is not biased, and is intermittently discarded. The band that has been freed by discarding can be used for transmission of non-real-time data.

  When the discard period calculated by the discard determination unit 1020 expires, the relay device 104 ends the discard of data in this bandwidth monitoring cycle (discard amount calculation cycle) (S1016; YES). The relay apparatus 104 waits without discarding data until the bandwidth monitoring period (discard amount calculation period) expires (S1004).

<Effect of this embodiment>
According to the present embodiment, real-time data with low importance can be discarded without being transmitted based on the transmission band of real-time data and non-real-time data.

  According to the present embodiment, it is possible to avoid the transmission band occupation by the real-time data and to suppress the delay of the non-real-time data. In addition, fairness between the real-time service and the non-real-time service when congestion occurs can be maintained, and a decrease in the communication speed of the user of the non-real-time service can be suppressed when congestion occurs. Furthermore, it is possible for a user of a real-time service to release a certain band without causing significant quality degradation, for example, a state in which video recognition becomes impossible.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. The second embodiment has common points with the first embodiment. Therefore, differences will be mainly described, and description of common points will be omitted.

  In this embodiment, data is discarded from the data storage unit in order to secure the capacity of the buffer (data storage unit).

<Overview>
The basic network configuration to which the present embodiment is applied is the same as the network configuration of the first embodiment in FIG.

  Regarding the discarding of data in the data storage unit (buffer) that is performed when the present embodiment is applied, the amount of discarding data with low importance of real-time data is determined using the following method. Based on the amount of data discarded, data with low importance of real-time data is discarded.

  (1) Measure the buffer occupancy rate (the ratio of real-time data and non-real-time data to the total buffer capacity of the data storage unit).

  (2) The total buffer capacity of the data storage unit, or the ratio of the data amount of real-time data to the data amount of real-time data and non-real-time data in the data storage unit, and the data amount of real-time data The amount of data discarded is determined based on the proportion of less important data in the real-time data.

  (3) Discard less important data from real-time data from the data storage unit.

  FIG. 13 is a diagram illustrating an example of the occupation state of the data storage unit (buffer). The buffer occupation in FIG. 13 indicates a state where real-time data and non-real-time data occupy the buffer. The example of FIG. 13 shows an example of the occupied state 21 of a buffer with many free buffers and the occupied state 22 of a buffer with few free buffers. In the case of the buffer occupation state 21 where there are many free buffers, there is no possibility of congestion, and there is little need to discard data in order to secure the buffer. On the other hand, in the case of the buffer occupancy state 22 where there are few free buffers, there is a possibility that congestion may occur. Therefore, it is highly necessary to discard data and secure a buffer.

  FIG. 14 and FIG. 15 are diagrams showing examples of the amount of real-time data discarded when the buffer occupation state is the occupation state 22 of FIG. FIG. 14 shows a case where the ratio of real-time data to non-real-time data is large. FIG. 15 shows a case where the ratio of real-time data to non-real-time data is small.

  As shown in FIG. 14, when the ratio of the real-time data is large, the data to be discarded is determined from the less important data among the real-time data. Since the ratio of the real-time data is large, the amount of the discard increases absolutely and relatively.

  On the other hand, as shown in FIG. 15, even when the ratio of the real-time data is small, the less important data among the real-time data is similarly discarded. However, since the ratio of real-time data is small, the amount of discard is reduced both absolutely and relatively.

<Details>
<Network configuration>
A configuration example (embodiment) of the network system that is one embodiment of the present invention can be the same as the configuration example of the network system of the first embodiment in FIG. Similar to the configuration example of the network system in FIG. 9, the network system includes a relay device 104, an AP (Access Point) 202 connected to the relay device 104, and a terminal 204.

  FIG. 16 is a basic block diagram of the relay apparatus. The relay device 104 includes a reception unit 2002, a data type determination unit 2004, a data storage unit (buffer) 2006, a transmission schedule unit 2008, a transmission unit 2010, a discard determination unit 2020, and an occupation rate determination unit 2022.

    The receiving unit 2002 receives data (real-time data and non-real-time data) from the network. The received data is, for example, an IP packet. The receiving unit 2002 transmits the received data to the data type determining unit 2004.

  The data type determination unit 2004 determines the type of received data, that is, whether it is a real-time data type or a non-real-time data type, or if it is real-time data, it is data with high importance or data with low importance. The data identification determination unit 1004 transmits the received data to the data storage unit 1006.

  The data storage unit 2006 stores data received from the data identification determination unit 2006. The data type of the stored data is sent to the occupation rate determination unit 2022. The data stored in the data storage unit 2006 is transmitted to the transmission schedule unit 2008 at the time of transmission. In addition, when there is a data discard instruction from the discard determination unit 2020, the data storage unit 2006 discards the data according to the instruction. That is, the data storage unit also functions as a discard unit.

  The occupancy rate determination unit 2022 determines the occupancy rate of real-time data (importance / high, importance / low) and non-real-time data in the data storage unit 2006 from the data type acquired from the data storage unit 2006. However, the method for acquiring the data type information is not particularly limited. That is, for example, when data is transmitted from the data type determination unit 2004 to the data storage unit 2006, the data type stored in the data storage unit 2006 may be received, and the transmission schedule unit 2008 receives data from the data storage unit 2006. , The transmission data type may be acquired from the transmission schedule unit 2008. Further, it is assumed that the total buffer capacity that can be stored in the data storage unit 2006 has been set in advance.

  The discard determination unit 2020 determines the amount of data to be discarded and its target from the occupancy rate of the data storage unit 2006 of the data type received from the occupancy rate determination unit 2022. Data to be discarded is data of low importance among real-time data. The discard determination unit 2020 of the relay apparatus 104 generates the following parameter and determines the discard amount based on this parameter.

(1) Ratio of the amount of data stored in the data storage unit (data amount of real-time data and data amount of non-real-time data) to the total buffer capacity of the data storage unit (2) Data amount stored in the data storage unit (3) Ratio of less important data amount to real-time data amount In the discard determination unit 2020, the data amount stored in the data storage unit 2006 is within a specific range. It is also possible to carry out the discard determination process only. Information on the amount of data in the data storage unit 2006 for determining whether or not to perform the discard determination process may be received from the occupation rate determination unit 2022 or directly from the data storage unit 2006.

  The transmission schedule unit 2008 reads data from the data storage unit 2006 according to the transmission priority order, and transfers the data to the transmission unit 2010. Here, the transmission schedule unit 2008 may receive data discard amount information from the discard determination unit 2020.

  The transmission unit 2010 transmits the data transferred from the transmission schedule unit 2008 to the destination. In addition, when there are a plurality of APs 202, the transmission unit 2010 performs distribution to the destination AP.

<Operation example>
The transmission schedule unit 2008 of the relay device 104 reads the transmission data from the data storage unit 2006 according to the transmission priority order, and transfers the data to the transmission unit 2010. In normal control, transmission of real-time data is prioritized during transmission.

(Batch disposal)
FIG. 17 is a diagram illustrating an example of a basic processing flow of the relay device when the data of the present embodiment is collectively discarded.

The occupation rate determination unit 2022 of the relay device 104 determines whether or not the discard control is ON (S2004). When the discard control is ON (S2), the occupation rate determination unit 2022 of the relay device 104
004; YES), the disposal control process is started.

  The occupation rate determination unit 2022 of the relay device 104 calculates the buffer occupation rate (S2008).

  The occupation rate determination unit 2022 of the relay device 104 obtains the data amount of the real-time data, the data amount of the non-real-time data stored in the data storage unit, the information on the total buffer capacity, and the like from the data storage unit 2006. The information on the real-time data includes information on whether the data is high in importance or low in importance.

  The occupation rate determination unit 2022 of the relay device 104 calculates the following parameters from these pieces of information.

A: Ratio of the amount of data stored in the data storage unit (the amount of real-time data and the amount of non-real-time data) to the total buffer capacity of the data storage unit B: The amount of real-time data relative to the amount of stored data Ratio C: Ratio of the data amount of less important data to the data amount of real-time data The relay apparatus 104 refers to each parameter (A, B, C) calculated by the occupancy rate determination unit 2022 and discards it. It is determined whether or not it is necessary (S2010). For example, when the ratio of the stored data amount to the total buffer capacity exceeds a predetermined value, the relay device 104 determines that discarding is necessary. It is also possible to adopt a configuration in which discard processing is always performed regardless of the ratio of the stored data amount to the total buffer capacity.

The relay device 104 calculates the discard amount according to the following equation (6) (S2012).

  The discard amount (D) is obtained by multiplying the amount of data of low importance by the above A, B, and C.

For example, in Formula (6), when A, B, and C are all 50%, the discard rate is 12.5%, and 12.5% of the data amount of less important data is the target of discard. . Furthermore, it is conceivable to apply a specific coefficient to the equation (6). This specific coefficient is determined depending on the buffer occupancy rate (A) of the data storage unit 2006. For example, a coefficient 30% may be set in advance when A is 30%, and a coefficient 70% may be set in advance when A is 60%. Assuming that this coefficient is F, the discard amount (E) is expressed as in the following equation (7).

  Only when the value of A is within a specific range, it may be a discard control target.

  FIG. 18 is a diagram illustrating an example of the discard control target range. Expression (6) or Expression (7) may be applied when the data stored in the data storage unit 2006 reaches or exceeds a certain ratio.

  The discard determination unit 2020 of the relay device 104 determines data to be discarded from data with low importance of real-time data according to the calculated discard amount, discards the data from the data storage unit 2006 (S2014), and performs processing Is finished (S2020).

(Intermittent disposal)
FIG. 19 is a diagram illustrating an example of a basic processing flow of the relay device when data is periodically discarded according to the present embodiment.

  When the processing is started (S3002), the occupation rate determination unit 2022 of the relay device 104 determines whether or not the bandwidth monitoring cycle (discard amount calculation cycle) has expired (S3004). This is because data is discarded at regular intervals. Accordingly, the next data discarding process is not performed before a certain period expires.

  When the bandwidth monitoring period expires (S3004; YES), the occupancy rate determination unit 2022 of the relay device 104 calculates the buffer occupancy rate (S3008).

  The occupancy rate determination unit 2022 of the relay device 104 obtains the same information and the like from the data storage unit 2006 as in the case of the collective discard (FIG. 17). The information on the real-time data includes information on whether the data is highly important or not important. The occupancy rate determination unit 2022 of the relay device 104 calculates the same parameters (A, B, C) as in the case of batch discard described above.

  The relay device 104 refers to each parameter (A, B, C) calculated by the occupancy rate determination unit 2022 and determines whether or not disposal is necessary (S3010). For example, the occupation rate determination unit 2022 of the relay device 104 determines that discarding is necessary when the ratio of the stored data amount to the total buffer capacity exceeds a predetermined value. It is also possible to adopt a configuration in which discard processing is always performed regardless of the ratio of the stored data amount to the total buffer capacity.

  The discard determining unit 2020 of the relay apparatus 104 calculates the discard amount according to the equation (6) (S3012). Further, the relay device 104 can also calculate the discard amount using the equation (7), as in the case of the collective discard. Further, it can be set as a discard control target only when the value of A is within a specific range.

Further, the discard determining unit 2020 of the relay apparatus 104 calculates a discard period. The discard determination unit 2020 determines the discard period (I) in the discard amount calculation cycle from the discard amount (D or E) and the maximum transmission band (G) of the relay device 104. The discard period (I) is given by the following equation (8).

Here, the system discard rate (H) is set in advance. The system discard rate (H) is a discard rate with respect to the maximum transmission band of the relay device 104. Therefore, the denominator of equation (8) means the amount discarded per unit time. Therefore, the discard period (I) is obtained as the discard amount divided by the amount discarded per unit time.

Here, when the discard period (I) exceeds the maximum discard period (discard amount calculation period), the discard period (I) is set as the maximum discard period (J). At this time, the system discard rate (H) is obtained as in the following equation (9).

  The discard determination unit 2020 of the relay apparatus 104 determines data to be discarded based on the calculated discard amount. The discard determination unit 2020 of the relay device 104 instructs the data storage unit 2006 to intermittently discard the determined discard data from the data stored in the data storage unit 2006 (S3014). When there are a plurality of streams, the amount of data to be discarded is determined for each stream so that the data to be discarded in a specific stream is not biased, and is intermittently discarded.

  When the discard period calculated by the discard determination unit 3020 expires, the relay device 104 ends the discard of data in this bandwidth monitoring cycle (discard amount calculation cycle) (S3016; YES). The relay apparatus 104 waits without discarding data until the bandwidth monitoring period (discard amount calculation period) expires (S3004).

<Effect of this embodiment>
According to this embodiment, real-time data with low importance can be discarded based on the amount of real-time data and non-real-time data stored in the data storage unit (buffer).

  According to the present embodiment, buffer occupancy due to real-time data can be avoided, and delay of non-real-time data can be suppressed. In addition, fairness between the real-time service and the non-real-time service when congestion occurs can be maintained, and a decrease in the communication speed of the user of the non-real-time service can be suppressed when congestion occurs. Furthermore, it is possible for a user of a real-time service to release a certain band without causing significant quality degradation, for example, a state in which video recognition becomes impossible.

[Others]
The above-described embodiments disclose the following invention. The following inventions can be appropriately combined as necessary.
(Appendix 1)
A receiving unit for receiving real-time data and non-real-time data;
A storage unit for storing real-time data and non-real-time data received by the receiving unit;
Percentage of transmission bandwidth of real-time data relative to the maximum transmission bandwidth or transmission bandwidth of real-time data and non-real-time data to be transmitted, or real-time data and non-real-time data stored in the storage unit A measurement unit that measures the proportion of real-time data,
A determination unit that determines a discard rate of real-time data based on the ratio;
Based on the discard rate, a discard unit that discards a part of real-time data to be transmitted without transmitting,
A transmission unit that transmits non-real-time data to be transmitted and real-time data that has not been discarded by the discard unit among real-time data to be transmitted;
A relay device comprising:
(Appendix 2)
The measuring unit is a ratio of the real-time data and non-real-time data transmission band to the maximum transmission band, or a ratio of the real-time data and non-real-time data to the total capacity of the storage unit. Measure some occupancy,
The determining unit determines the discard rate when the occupation rate exceeds a predetermined value;
The relay device according to attachment 1.
(Appendix 3)
The discard unit discards real-time data with low importance of a transmission target based on the discard rate without transmitting it,
The relay device according to appendix 1 or 2.
(Appendix 4)
The discard unit is a discard rate that is a value obtained by raising a power of a predetermined coefficient to a ratio of a transmission band of real-time data to a transmission band of the maximum transmission band or real-time data to be transmitted and non-real-time data,
The relay device according to any one of appendices 1 to 3.
(Appendix 5)
The predetermined coefficient is determined based on a ratio of a transmission band of real-time data to a transmission band of the maximum transmission band or real-time data to be transmitted and non-real-time data.
The relay device according to attachment 4.
(Appendix 6)
The discard unit determines the discard rate for each predetermined period.
The relay device according to any one of appendices 1 to 5.
(Appendix 7)
The discard unit discards the real-time data intermittently within the predetermined period based on the determined discard rate.
The relay device according to attachment 6.
(Appendix 8)
The discard unit intermittently discards the real-time data based on the discard rate in a period set within the predetermined period and less than the length of the predetermined period.
The relay device according to appendix 7.
(Appendix 9)
The discard unit determines the set period based on the discard rate;
The relay device according to attachment 8.
(Appendix 10)
Receive real-time and non-real-time data,
Stores received real-time data and non-real-time data,
Percentage of transmission bandwidth of real-time data relative to the maximum transmission bandwidth or transmission bandwidth of real-time data and non-real-time data to be transmitted, or real-time data relative to stored real-time data and non-real-time data Measure the proportion of
Determine the discard rate of real-time data based on the ratio,
Based on the discard rate, discard part of the real-time data to be transmitted without transmitting,
Send non-real-time data to be sent and real-time data that was not discarded among real-time data to be sent,
A relay method in a relay device.
(Appendix 11)
The ratio of the transmission bandwidth of real-time data and non-real-time data to the maximum transmission bandwidth, or the ratio of the amount of real-time data and non-real-time data to the total capacity of the storage unit in which the data is stored Measure the occupancy,
Determining the discard rate when the occupancy exceeds a predetermined value;
The relay method in the relay device according to appendix 10, wherein
(Appendix 12)
Based on the discard rate, discard real-time data of low importance for transmission without transmitting,
12. The relay method in the relay device according to appendix 10 or 11, characterized in that.
(Appendix 13)
The discard rate is a value obtained by raising a power of a predetermined coefficient to the ratio of the transmission bandwidth of the real-time data to the transmission bandwidth of the maximum transmission bandwidth or the real-time data to be transmitted and the non-real-time data.
The relay method in the relay device according to any one of appendices 10 to 12, characterized in that: (Appendix 14)
The predetermined coefficient is determined based on a ratio of a transmission band of real-time data to a transmission band of the maximum transmission band or real-time data to be transmitted and non-real-time data.
14. The relay method in the relay device according to appendix 13, wherein
(Appendix 15)
Determining the discard rate for each predetermined period;
15. The relay method in the relay device according to any one of appendices 10 to 14, characterized in that: (Appendix 16)
Based on the determined discard rate, the real-time data is discarded intermittently within the predetermined period.
The relay method in the relay device according to Supplementary Note 15, wherein
(Appendix 17)
Within the predetermined period, the real-time data is discarded based on the discard rate intermittently in a period set to be equal to or less than the length of the predetermined period.
The relay method in the relay device according to Supplementary Note 16, wherein
(Appendix 18)
Determining the set period based on the discard rate;
18. The relay method in the relay device according to appendix 17, wherein

It is a figure which shows a basic network structure. It is a figure which shows the example of the occupation state of the transmission band with respect to the maximum transmission band of a relay apparatus. It is a figure which shows the figure which shows the example of the discard amount of real time type data when the ratio of real time type data is large. It is a figure which shows the figure which shows the example of the discard amount of real time type data when the ratio of real time type data is small. It is a figure which shows the example of the discard data in importance and low data. It is a figure which shows the example of an intermittent discard. It is a figure which shows the example of intermittent discard when a some stream exists. It is a figure which shows the example of the relationship between a discard amount calculation period and a data discard period. It is a figure which shows the network structural example. It is a figure which shows the basic block example of a relay apparatus. It is a figure which shows the example of the basic processing flow of a relay apparatus. It is a figure which shows the relationship between the coefficient n and a discard rate. It is a figure which shows the occupation state of a buffer. It is a figure which shows the figure which shows the example of the discard amount of real time type data when the ratio of real time type data is large. It is a figure which shows the figure which shows the example of the discard amount of real time type data when the ratio of real time type data is small. It is a figure which shows the basic block example of a relay apparatus. It is a figure which shows the example of the basic processing flow (batch disposal) of a relay apparatus. It is a figure which shows the example of the discard control object range. It is a figure which shows the example of the basic processing flow (intermittent discard) of a relay apparatus. It is a figure which shows the structural example of wireless LAN. It is a figure which shows the structural example of 3GPP (cellular). It is a figure which shows generation | occurrence | production of the stay by the synchronization of the transmission period of each stream.

Explanation of symbols

11 Occupancy status of transmission band (1)
12 Occupancy status of transmission band (2)
21 Buffer occupancy status (1)
22 Buffer occupancy status (2)
102 receiving device 104 relay device 106 transmitting device 202 AP (access point)
204 terminal 1002 receiving unit 1004 data type determining unit 1006 data storing unit 1008 transmission scheduling unit 1010 transmitting unit 1020 discard determining unit 1022 occupancy rate determining unit 2002 receiving unit 2004 data type determining unit 2006 data storing unit 2008 transmission scheduling unit 2010 transmitting unit 2020 Disposal determination unit 2022 Occupancy rate determination unit

Claims (4)

A receiving unit for receiving real-time data and non-real-time data;
A storage unit for storing real-time data and non-real-time data received by the receiving unit;
Percentage of transmission bandwidth of real-time data relative to the maximum transmission bandwidth or transmission bandwidth of real-time data and non-real-time data to be transmitted, or real-time data and non-real-time data stored in the storage unit A measurement unit that measures the proportion of real-time data,
A determination unit that determines a discard rate of real-time data based on the ratio;
Based on the discard rate, a discard unit that discards a part of real-time data to be transmitted without transmitting,
A transmission unit that transmits non-real-time data to be transmitted and real-time data that has not been discarded by the discard unit among real-time data to be transmitted;
A relay device comprising: The measuring unit is a ratio of the real-time data and non-real-time data transmission band to the maximum transmission band, or a ratio of the real-time data and non-real-time data to the total capacity of the storage unit. Measure some occupancy,
The determining unit determines the discard rate when the occupation rate exceeds a predetermined value;
The relay device according to claim 1. The discard unit discards real-time data with low importance of a transmission target based on the discard rate without transmitting it,
The relay device according to claim 1 or 2. Receive real-time and non-real-time data,
Stores received real-time data and non-real-time data,
Percentage of transmission bandwidth of real-time data relative to the maximum transmission bandwidth or transmission bandwidth of real-time data and non-real-time data to be transmitted, or real-time data relative to stored real-time data and non-real-time data Measure the proportion of
Determine the discard rate of real-time data based on the ratio,
Based on the discard rate, discard part of the real-time data to be transmitted without transmitting,
Send non-real-time data to be sent and real-time data that was not discarded among real-time data to be sent,
A relay method in a relay device.

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