JP4320024B2 - Transmission rate control method using error correction packet and communication apparatus using the same - Google Patents

Description

  The present invention relates to transmission rate control, and more particularly to a transmission rate control method using an error correction packet and a communication apparatus using the same.

  Recently, there is an increasing demand for transmission of real-time data such as transmission / reception of multimedia materials and voice communication on a network.

  On the other hand, with the development of communication and network technology, the recent network environment has changed from a wired network environment using a wired medium such as a coaxial cable or an optical cable to a wireless network environment using wireless signals of various frequency bands.

  By the way, unlike a wired network, a wireless network does not have a fixed data transmission path. Therefore, a wireless network has a limited bandwidth compared to a wired network, and has variable traffic characteristics caused by movement of communication devices and changes in characteristics of wireless links. For this reason, the wireless network has a higher packet loss rate than the wired network.

  In addition, even if packets are transmitted so that the communication device fits the initial network bandwidth, the bandwidth decreases as the number of service targets increases, resulting in a network congestion condition and stability. It is impossible to guarantee the packet transmission.

  Therefore, packet loss that occurs in a wireless network can be classified into packet loss due to lack of available bandwidth and packet loss due to the characteristics of the wireless link. If the available bandwidth decreases and packet loss occurs, the transmission rate needs to be reduced. However, if temporary packet loss occurs due to the characteristics of the radio link, the transmission rate must be lowered. There is no. In particular, when transmitting real-time data as in a streaming service, it is important to maintain the transmission rate and guarantee real-time performance by reducing the transmission rate against temporary packet loss. Therefore, when packet loss occurs, a technique for analyzing the cause and appropriately adjusting the transmission rate is required.

  In the prior art, there is a method of estimating a congestion loss when a packet adjacent to a packet whose transmission time is longer than an expected value is lost by using a ROTT (Relational One Way Round Trip Time). However, such a method is not suitable for transmitting real-time data because it requires retransmission of response packets and lost packets for transmitted packets.

  On the other hand, International Publication No. WO01 / 84731 A1 (Methods and systems for forward error correction based loss loss recovery for interactive video transmission, which is a packet loss correction technique for multimedia data packets) The current situation is that no solution can be presented for situations where a large amount of packets can only be lost continuously due to the reduced width.

  An object of the present invention is to predict a bandwidth by using an error correction packet used for restoration of a lost data packet, and thereby control a transmission rate.

  The object of the present invention is not limited to the object described above, and other objects not described above can be clearly understood by those skilled in the art from the following.

  To achieve the above object, a transmission rate control method using an error correction packet according to an embodiment of the present invention receives a first packet group in which data packets and error correction packets are configured at a predetermined ratio. Transmitting a second packet group in which a ratio of error correction packets is adjusted according to feedback information regarding the first packet group, and adjusting a transmission rate according to feedback information regarding the second packet group. including.

  In order to achieve the above object, a transmission rate control method using an error correction packet according to an embodiment of the present invention provides a packet group in which data packets and error correction packets are configured at a predetermined rate to a predetermined transmission rate. And when the overall packet loss rate included in the feedback information of the receiving device for the packet group is less than a threshold, the ratio of the error correction packets and the transmission rate are increased, and the feedback information If the total packet loss rate included in the packet is equal to or greater than a threshold, the error correction packet ratio and the transmission rate are decreased.

  In order to achieve the above object, a communication apparatus according to an embodiment of the present invention includes a receiving unit that receives feedback information including information on packet loss, and a rate and a transmission rate of error correction packets by the feedback information. A control unit for adjusting, a packet providing unit for providing an error correction packet and a data packet according to a ratio adjusted by the control unit, and a packet provided by the packet providing unit is transmitted at a transmission rate adjusted by the control unit Includes a transmitter.

  Specific matters of other embodiments are included in the detailed description and drawings.

  Advantages and features of the present invention and methods of achieving them will be apparent with reference to the embodiments described in detail below in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be carried out in various forms different from each other, and the embodiments are merely to complete the disclosure of the present invention. The present invention is only defined by the scope of the claims, and is provided to fully inform those skilled in the art to the scope of the invention. Throughout the specification, the same reference numerals refer to the same components.

  According to the transmission rate control method using the error correction packet and the communication apparatus using the error correction packet according to the present invention as described above, the usable bandwidth is predicted through the error correction packet, thereby adjusting the transmission rate. There is an effect that can be.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a transmission rate control system according to an embodiment of the present invention.

  The illustrated system includes two communication devices 100 and 200. Each of the communication devices 100 and 200 is a computer device having a data calculation capability and capable of wired or wireless communication.

  In the illustrated communication devices 100 and 200, one can transmit a data packet including multimedia data, and the other receives the data packet and provides predetermined feedback information. Hereinafter, for convenience of explanation, a communication device that transmits a data packet is referred to as a transmission device, and a communication device that provides feedback information after receiving a data packet is referred to as a reception device. In this embodiment, the communication device A (100) functions as a transmission device, and the communication device B (200) functions as a reception device.

  Transmitting apparatus 100 transmits an error correction packet together with a data packet. The error correction packet is a packet including information that can be recovered when the data packet is lost. As a preferred embodiment of the error correction packet, an FEC (Forward Error Correction) packet can be used. The transmission apparatus 100 changes the ratio of error correction packets transmitted together with the data packet according to feedback information provided from the reception apparatus 200, and information on packet loss of packets transmitted after the ratio of error correction packets changes. The transmission rate is adjusted according to feedback information including.

  When a part of the data packets transmitted from the transmitting apparatus 100 is lost, the receiving apparatus 200 restores the lost data packet using the error correction packet. At this time, the receiving apparatus 200 provides feedback information including information regarding the packet loss of the packet transmitted from the transmitting apparatus 100. The feedback information provided by the receiving apparatus 200 uses the data packet received from the transmitting apparatus 100 during the threshold time, the packet loss rate for the entire error correction packet (hereinafter referred to as the total packet loss rate), and the error correction packet. And a data packet loss rate resulting from restoring lost data packets. The feedback information provided by the receiving apparatus 200 may further include various information regarding the network status and service quality.

  It is preferable that the packet providing operation of the transmitting device 100 and the feedback information providing operation of the receiving device 200 are performed through RTP (real time protocol) and RTCP (RTP control protocol), respectively. However, the present invention is not limited to this.

  On the other hand, although not shown, an intermediate node that relays packet transmission between the transmission apparatus 100 and the reception apparatus 200 may exist. At this time, the packet transmission path between the transmission device 100 and the reception device 200 may be all wireless or only a part may be wireless. Therefore, at least one of the transmission device 100 and the reception device 200 can be a wireless communication device. For example, the transmitting device 100 and the receiving device 200 may be mobile devices such as a mobile phone, a PDA, and a notebook computer, but the present invention is not limited to this.

  Hereinafter, the transmission device 100 and the reception device 200 according to the embodiment of the present invention will be described in more detail with reference to FIGS.

  FIG. 2 is a block diagram showing a transmission apparatus according to an embodiment of the present invention.

  The illustrated transmission apparatus 100 includes an application unit 110, a packet providing unit 120, a transmission unit 130, a reception unit 140, and a control unit 150.

  The application unit 110 provides data to be transmitted. Preferably, the application unit 110 can provide multimedia data such as moving images and sounds. For example, when the transmission device 100 functions as a moving image providing server, the application unit 110 can be MPEG4, H.264, or the like. Video data coded with a compression technique such as H.264 can be provided.

  The packet providing unit 120 packetizes the data provided from the application unit 110 and provides a data packet. At this time, the packet providing unit 120 can provide both error correction packets. The error correction packet includes information that can recover even if a part of the data packet is lost.

  An FEC packet can be used as a preferred embodiment of the error correction packet. In this case, in order to provide the FEC packet, the packet providing unit 120 includes various coding methods using an XOR (eXclusive OR) operation, a Reed-Solomon coding method that converts information of each data packet into a polynomial count, and the like. Any FEC scheme can be used.

  For example, when a coding method using an XOR operation is used, the packet providing unit 120 can generate an FEC packet by taking an XOR operation between two or more data packets. If two data packets are used to generate one FEC packet, the packet providing unit 120 arranges the two data packets in a bit stream and then matches the size of the long data packet. To pad a short data packet. Thereafter, the bit stream created from the result of taking the XOR operation constitutes one FEC packet between the bit streams having the same length.

  An embodiment of a packet provided by the packet providing unit 120 using such a method is shown in FIG. In FIG. 3, hatched blocks 330 and 360 are FEC packets, and the remaining blocks 310, 320, 340, and 350 are data packets. In the drawing, each FEC packet is generated by an XOR operation result between two data packets, and an f (a, b) packet 330 is an XOR between an a packet 310 and a b packet 320. The f (c, d) packet 360 is generated by an XOR operation between the c packet 340 and the d packet 350. The packet providing unit 120 can use RTP for providing a packet.

  Referring to FIG. 2, the transmission unit 130 transmits a series of packets provided from the packet providing unit 120 to the reception device 200.

  The reception unit 140 receives feedback information regarding the packet transmitted by the transmission unit 130 from the reception device 200. The feedback information includes an overall packet loss rate and a data packet loss rate.

  The control unit 150 controls the rate and transmission rate of error correction packets. In particular, the control unit 150 can adjust the rate and transmission rate of error correction packets according to feedback information received by the receiving unit 140 from the receiving device 200.

  On the other hand, in FIG. 2, the transmission unit 130 and the reception unit 140 are shown as separate functional blocks, but this is exemplary, and the transmission unit 130 and the reception unit 140 have integrated functionality. It can also be realized as a block.

  FIG. 4 is a block diagram showing a receiving apparatus according to an embodiment of the present invention.

  The illustrated receiving apparatus includes a receiving unit 210, a restoring unit 220, a loss rate calculating unit 230, a feedback information providing unit 240, and a transmitting unit 250.

  The reception unit 210 receives a series of packets from the transmission device 100. The received packet includes a data packet and an error correction packet.

  The restoration unit 220 restores the lost data packet using the received error correction packet. The data packet restoration operation can be performed in a manner corresponding to the scheme used by the transmission apparatus 100 to generate the error correction packet. For example, if the transmitting apparatus 100 transmits a packet as shown in FIG. 3 and the b packet 320 is lost, the restoration unit 220 uses the a packet 310 and the f (a, b) packet 330. B packet 320 can be restored by performing an XOR operation between

  The loss rate calculation unit 230 performs a recovery operation on the lost data packet using the overall packet loss rate for the packet received during the threshold time and the error correction packet received by the recovery unit 220 during the threshold time. Calculate the resulting data packet loss rate. Whether or not there is a lost packet among the packets transmitted by the transmission device 100 can be confirmed via a sequence number included in the received packet. An embodiment of the loss rate calculation by the loss rate calculation unit 230 will be described with reference to FIG.

  The number given to each packet in FIG. 5 is for indicating the number of data packets and error correction packets, and does not mean the sequence number of the packet. Further, in FIG. 5, the error correction packet and the data packet are shown as being grouped separately, but the error correction packet is distributed among the data packets as shown in FIG. You can also.

  As shown in FIG. 5, the total number of packets transmitted from the transmitting apparatus 100 to the receiving apparatus 200 is “N + M”, which is a combination of “N” data packets and “M” error correction packets. is there. On the other hand, the packets normally received by the receiving apparatus 200 are “N-x” data packets and “M-y” error correction packets. Therefore, in the present embodiment, the number of lost data packets is ‘x’, and the number of lost error correction packets is ‘y’. In such a case, the overall packet loss rate calculated by the loss rate calculation unit 230 is

一方、復元部２２０が受信した誤り訂正パケットを用いて復元作業を行った結果、損失されたデータパケット中、ｚ個のデータパケットが復元されれば、損失率計算部２３０が計算するデータパケット損失率は、

On the other hand, if z data packets are restored among the lost data packets as a result of the restoration operation using the error correction packet received by the restoration unit 220, the data packet loss calculated by the loss rate calculation unit 230 Rate is

損失率計算部２３０によって行われる損失率計算作業は、一定時間間隔ごとに行われる。したがって、損失率計算部２３０は、以前に損失率を計算した時点から閾値時間が経過するまで受信されたパケットに対し全体パケット損失率およびデータパケット損失率を計算することができる。

The loss rate calculation work performed by the loss rate calculation unit 230 is performed at regular time intervals. Therefore, the loss rate calculation unit 230 can calculate the total packet loss rate and the data packet loss rate for the received packets until the threshold time elapses from the time when the loss rate was previously calculated.

  Referring to FIG. 4, the feedback information providing unit 240 provides feedback information including the total packet loss rate and the data packet loss rate calculated by the loss rate calculating unit 230. In addition, the feedback information provided by the feedback information providing unit 240 may further include QoS (Quality of Service) information such as SNR (signal to noise ratio), jitter interval, and packet delay time. The feedback information providing unit 240 can use RTCP to provide such feedback information.

  The transmission unit 250 transmits the feedback information provided from the feedback information providing unit 240 to the transmission device 100.

  On the other hand, in FIG. 4, the reception unit 210 and the transmission unit 250 are illustrated as separate functional blocks, but this is exemplary, and the reception unit 210 and the transmission unit 250 are integrated functionalities. It can also be realized as a block.

  Each functional block referred to as “unit” in the description of FIGS. 2 and 4 may be a kind of module. Module here refers to software or a hardware component such as a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC), where the module plays a role. However, the module is not limited to software or hardware. A module can be configured to reside in a storage medium that can be addressed, or can be configured to run one or more processors. Thus, by way of example, a module is comprised of components such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware. , Including microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided by the components and modules can be combined as a smaller number of components and modules or further separated as additional components and modules.

  Hereinafter, the operation processes of the transmission device 100 and the reception device 200 described above will be described in more detail with reference to FIGS.

  FIG. 6 is a flowchart schematically showing a transmission rate control process between the transmitting apparatus and the receiving apparatus according to an embodiment of the present invention.

  The transmission device 100 transmits the first packet group in which the data packets and the error correction packets are configured at a predetermined ratio to the reception device (S10).

  Receiving device 200 receives this, generates feedback information about the received packet (S20), and transmits this to transmitting device 100 (S30).

  The transmission apparatus 100 adjusts the ratio of error correction packets based on feedback information about the first packet group (S40), and transmits the second packet group in which the ratio of error correction packets is adjusted to the reception apparatus 200 (S50).

  The receiving device 200 that has received this generates feedback information regarding the received packet (S60), and transmits this to the transmitting device 100 (S70).

  The transmitting apparatus 100 adjusts the transmission rate according to feedback information about the second packet group (S80), and transmits the remaining packets at the adjusted transmission rate (S90).

  Hereinafter, each operation | movement of the transmitter 100 and the receiver 200 is demonstrated.

  FIG. 7 is a flowchart illustrating a feedback information providing process according to an embodiment of the present invention. The illustrated process is performed by the receiving apparatus 200.

  First, when the reception unit 210 receives a series of packets from the transmission device 100 (S110), the loss rate calculation unit 230 calculates an overall packet loss rate for the received packets (S120). The total packet loss rate calculation is performed every threshold time interval. Therefore, the loss rate calculation unit 230 calculates the total packet loss rate for the received packets until the threshold time elapses from the time when the total packet loss rate was calculated previously. Data packets and error correction packets are mixed in the received packets, and the total packet loss rate indicates the loss rate between the data packets received during the threshold time and the entire error correction packets. The total packet loss rate may be calculated as a ratio between the number of packets that should be normally received and the number of lost packets during the threshold time interval, as described with reference to FIG. it can.

  Meanwhile, the restoration unit 220 restores the lost data packet using the received error correction packet (S130).

  When the restoration operation of the data packet is completed by the restoration unit 220, the loss rate calculation unit 230 calculates the loss rate of the data packet (S140). The loss rate of data packets is calculated as a ratio between the number of data packets to be received normally and the number of lost data packets during the threshold time interval as described with reference to FIG. The

  Thereafter, the feedback information providing unit 240 generates feedback information including the overall packet loss rate and the data packet loss rate calculated by the loss rate calculating unit 230 (S150). In addition, the feedback information may further include QoS information such as SNR, jitter interval, and packet delay time.

  Thereafter, the transmission unit 250 transmits feedback information to the transmission device 100 (S160).

  Thus, the process of providing the overall packet loss rate and the data packet loss rate to the transmitting apparatus 100 can be performed via RTCP. That is, the overall packet loss rate and the data packet loss rate are included in the RTCP feedback information as a kind of feedback information and transmitted to the transmitting apparatus 100.

  The process of FIG. 7 is continuously performed by the receiving apparatus until all the packet transmissions from the transmitting apparatus are completed.

  Hereinafter, an operation process of the transmission apparatus will be described.

  FIG. 8 is a flowchart showing a transmission rate control method according to an embodiment of the present invention. The illustrated process is performed by the transmission apparatus 100.

  First, if the packet providing unit 120 provides a first packet group in which data packets and error correction packets are configured at a predetermined ratio (S210), the transmitting unit 130 receives the first packet group at a predetermined transmission rate. The data is transmitted to the device 200 (S220). The ratio and transmission rate of error correction packets can be set in advance by the control unit 150 according to the type of data packet to be transmitted, the usable network bandwidth, and the like.

  If the transmission unit 130 transmits a packet included in the first packet group, the reception unit 140 can receive feedback information about the first packet group from the reception device 200 (S230). As described above, the feedback information includes the overall packet loss rate and the data packet loss rate.

  At this time, the controller 150 determines whether or not the total packet loss rate included in the feedback information is equal to or greater than a threshold (S240).

  If the overall packet loss rate is less than the threshold, it is considered that the packet loss currently occurring is temporarily caused by the characteristics of the wireless network such as interference. Further, such a level of packet loss does not significantly affect the packet transmission process between the transmission device 100 and the reception device 200. Therefore, when the total packet loss rate is less than the threshold, the control unit 150 can maintain the current transmission rate and the rate of error correction packets as they are (S250). In this case, the packet providing unit 120 can provide a packet group including the same percentage of error correction packets as the conventional one, and the transmitting unit 130 can maintain the same level of transmission rate as the conventional one.

  However, if the overall packet loss rate is equal to or greater than the threshold, packet loss may occur due to a lack of available bandwidth. In such a case, the control unit 150 stores the data packet loss rate included in the feedback information (S260), determines whether the transmission rate should be reduced, and performs a transmission rate adjustment operation accordingly (S270). This will be described more specifically with reference to FIG.

  FIG. 9 is a flowchart showing step S270 of FIG. 8 more specifically.

  If the total packet loss rate is equal to or greater than the threshold, the control unit 150 can increase the rate of error correction packets and the transmission rate (S310). Here, the amount of increase in the rate of error correction packets may have a preset value. Alternatively, the increase amount of the error correction packet ratio may be dynamically determined to have a value proportional to the total packet loss rate included in the feedback information regarding the first packet group. Also, increasing the ratio of error correction packets here means increasing the number of error correction packets output per unit time while maintaining the number of data packets output per unit time constant. Means that. Therefore, the amount of increase in the transmission rate can be determined by the degree to which the rate of error correction packets has increased.

  Under the control of the control unit 150, the packet providing unit 120 provides a second packet group in which the ratio of error correction packets is increased compared to the first packet group (S315), and the transmission unit 130 transmits the second packet group to the receiving device 200. (S320).

  If the transmission unit 130 transmits a packet included in the second packet group, the reception unit 140 can receive feedback information about the second packet group from the reception device 200 (S325).

  At this time, the controller 150 stores the received feedback information (S330), and determines whether or not a threshold time has elapsed since the start of transmission of the second packet group (S335). If the threshold time has not elapsed, the control unit 150 continues to store feedback information received by the receiving unit 140. Here, the threshold time has a different meaning from the threshold time mentioned in FIG.

  On the other hand, if the threshold time elapses from the start of transmission of the second packet group, the control unit 150 is included in each received feedback information until the threshold time elapses from the transmission of the second packet group. An average value of the obtained data packet loss rates is calculated (S340).

  Thereafter, the control unit 150 compares the data packet loss rate stored in step (S260) of FIG. 8 with the average value calculated in step (S340) of the present embodiment (S345).

  As a result of the comparison, if the average value is less than the data packet loss rate stored in step (S260) of FIG. 8, this increased the transmission rate, but a larger number of data packets were recovered through the error correction packet. Means the result. For example, as shown in FIG. 10a, if the available bandwidth is sufficient, the overall packet loss rate is greater than or equal to a threshold value, so that the rate of error correction packets is increased, thereby increasing the transmission rate. Even if it is slightly increased (time t1), the data packet loss rate can be reduced more than before due to an increase in error correction packets.

  Therefore, in such a case, the total packet loss rate in the step (S240) of FIG. 8 is equal to or greater than the threshold because the temporary packet loss that occurred due to the characteristics of the wireless environment in a situation where the bandwidth is sufficient. Since it can be determined that this is the cause, the control unit 150 maintains the ratio and the transmission rate of the error correction packets at the level at the time of transmitting the first packet group (S350). Accordingly, the packet providing unit 120 provides a packet group including error correction packets at the same rate as the existing one, and the transmitting unit 130 transmits the packet at the same transmission rate as the existing one.

  However, if the average value is equal to or greater than the data packet loss rate stored in step (S260) of FIG. 8 as a result of the comparison in step (S345), this means that more packets are lost due to the increase in the transmission rate. To do. For example, as shown in FIG. 10b, if the available bandwidth is not sufficient, the overall packet loss rate is greater than or equal to the threshold value, so that the rate of error correction packets is increased, thereby increasing the transmission rate. Increases slightly (time t1), more packets are lost, so even if the rate of error correction packets increases, this does not improve the data packet loss rate.

  Therefore, in such a case, it can be determined that the total packet loss rate in the step (S240) of FIG. 8 is equal to or greater than the threshold value is caused by the packet loss caused by the lack of bandwidth. The transmission rate is reduced from the time of transmitting the first packet group (S355). At this time, the decrease rate of the transmission rate may have a preset value. Alternatively, the amount of decrease in the transmission rate may be dynamically determined to have a value proportional to the average value calculated in step (S340). At this time, the controller 150 can reduce the rate of error correction packets to the level at the time of transmitting the first packet group.

  On the other hand, even when the transmission rate is lower than the existing level, the transmitting apparatus 100 can perform the work of increasing the transmission rate to the existing level under a certain condition, which will be described with reference to FIG.

  FIG. 11 is a flowchart showing a transmission rate control method according to another embodiment of the present invention.

  After the transmission rate is lowered in step (S355) in FIG. 9, when each total packet loss rate included in the feedback information received during the threshold time is equal to or less than the threshold value, the transmission apparatus 100 has improved network conditions. Search for excess bandwidth available. The threshold value and the threshold time mentioned in this embodiment have different meanings from the threshold value and the threshold time mentioned in FIGS.

  If the packet providing unit 120 provides a packet group in which data packets and error correction packets are configured at a predetermined ratio (S410), the transmitting unit 130 receives the provided packet group at a predetermined transmission rate. (S420). At this time, the ratio of error correction packets and the transmission rate can maintain the levels set in step (S355) of FIG.

  If the transmission unit 130 transmits a packet included in the packet group, the reception unit 140 can receive feedback information including information on the loss of the packet included in the packet group from the reception device 200 (S430).

  At this time, the controller 150 determines whether or not the total packet loss rate included in the feedback information is equal to or greater than a threshold (S440).

  When the total packet loss rate is less than the threshold, the controller 150 can increase the rate and transmission rate of error correction packets (S450). Here, the increase amount of the error correction packet ratio may have a previously defined value. In addition, increasing the rate of error correction packets here means increasing the number of error correction packets output per unit time while maintaining the number of data packets output per unit time constant. Means that Therefore, the amount of increase in the transmission rate can be determined by the degree to which the rate of error correction packets has increased. Alternatively, the increase amount of the transmission rate can be determined by a preset value, and the increase amount of the error correction packet ratio can be determined by the increase amount of the transmission rate.

  Accordingly, the packet providing unit 120 provides a packet group in which the ratio of error packets is increased (S460), and the transmitting unit 130 transmits the packet group to the receiving device 200 (S420). As described above, when the operations from step (S420) to step (S460) are repeated, the transmission rate sequentially increases.

  While performing such an operation, if the overall packet loss rate included in the feedback information received by the receiving unit 140 is equal to or greater than the threshold value as a result of the determination in step (S440), the bandwidth that the current transmission rate can use is set. The controller 150 can determine that the packet rate has been exceeded, and adjust the rate of error correction packets to the rate at which the first packet group is provided (S410) (S470). At this time, the amount of decrease in the transmission rate may be determined according to a preset threshold value or may be dynamically set to be proportional to the overall packet loss rate. Also, if the ratio of error correction packets is lowered to the existing level, the number of data packets increases in the packet group provided by the packet providing unit 120, and the number of error correction packets decreases.

  FIG. 12 shows the change in transmission rate and the number of packets transmitted per unit time due to the operation of the embodiment of FIG.

  As shown in FIG. 12, when the rate of error correction packets is increased and the rate of transmission increases, the rate of transmission exceeds the available bandwidth (300). The total packet loss rate included in the received feedback information exceeds the threshold, and at this time (t2), the transmitting apparatus 100 decreases the transmission rate by a certain amount. Therefore, the transmission device 100 can maintain a transmission rate close to the currently available bandwidth.

  On the other hand, when looking at the number of packets output per unit time due to a change in the transmission rate, the number of error correction packets output per unit time increases while the transmission rate is sequentially increased. Thereafter, when the transmission rate is determined to exceed the usable bandwidth (t2), the transmission rate is decreased, so that the total number of packets output per unit time is also reduced. At this time, since the ratio of error correction packets also decreases, the number of data packets in the entire packet increases and the number of error correction packets decreases. Accordingly, it is possible to predict a usable bandwidth in a state where no loss of data packet is induced, and to increase the transmission rate so as to match the predicted bandwidth.

  On the other hand, the embodiment of FIG. 11 can also be applied to predict a usable bandwidth when the transmission apparatus 100 starts packet transmission to the reception apparatus 200. In such a case, the ratio and transmission rate of error correction packets in step (S410) can have values set in advance by the control unit 150 according to the type of data packet to be transmitted, network conditions, and the like.

  The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention has its technical idea and essential features as long as the person has ordinary knowledge in the technical field to which the present invention belongs. Obviously, it can be implemented in other specific forms without modification. Accordingly, it will be understood that the embodiments described above are illustrative in all aspects and not limiting.

It is the figure which showed the transmission rate control system which concerns on one embodiment of this invention. It is the block diagram which showed the transmitter which concerns on one embodiment of this invention. FIG. 3 is a diagram illustrating a series of packets provided by the packet providing unit of FIG. 2 according to an embodiment of the present invention. It is the block diagram which showed the receiver which concerns on one embodiment of this invention. It is a figure for demonstrating the loss rate which the loss rate calculation part of FIG. 4 calculates by one embodiment of this invention. It is the flowchart figure which showed roughly the transmission rate control process between the transmitter which concerns on one embodiment of this invention, and a receiver. It is the flowchart figure which showed the feedback information provision process which concerns on one embodiment of this invention. It is the flowchart figure which showed the transmission rate control method which concerns on other embodiment of this invention. It is the flowchart figure which showed the step (S270) of FIG. 8 more concretely. It is the figure which showed the condition of the bandwidth and transmission rate which concern on one embodiment of this invention. It is the figure which showed the condition of the bandwidth and transmission rate which concern on other embodiment of this invention. It is the flowchart figure which showed the transmission rate control method which concerns on other embodiment of this invention. It is the figure which showed the transmission rate control process which concerns on one embodiment of this invention.

Explanation of symbols

110 Application unit 120 Packet providing unit 130 Transmitting unit 140 Receiving unit 150 Control unit 210 Receiving unit 220 Restoring unit 230 Loss rate calculating unit 240 Feedback information providing unit 250 Transmitting unit

Claims (10)

Transmitting a first packet group in which data packets and error correction packets are configured at a predetermined ratio to a receiving device;
Receiving feedback information about the first packet group from the receiving device;
When the overall packet loss rate included in the feedback information related to the first packet group is equal to or greater than a threshold, transmitting the second packet group in which the ratio of error correction packets is increased from the first packet group to the receiving device; ,
Receiving feedback information about the second packet group from the receiving device during a threshold time;
When the average value of the data packet loss rates included in the feedback information regarding the second packet group received during the threshold time is equal to or greater than the data packet loss rate included in the feedback information regarding the first packet group. Reducing the transmission rate, and
The overall packet loss rate included in the feedback information is calculated by using the data packet and the error correction packet included in the packet group received by the receiving device, and the ratio between the total packet received and the lost packet. ,
The data packet loss rate included in the feedback information is obtained by using the error correction packet included in the packet group received by the receiving device to restore the lost data packet in the data packet included in the packet group. Calculated by the result of
A transmission rate control method using an error correction packet characterized by the above . The increase amount of the ratio of error correction packets included in the second packet group is either a value proportional to the total packet loss rate included in the feedback information regarding the first packet group or a preset value. rate control method using the error correction packet according to claim 1 having a one value. The decrease in the rate, the value proportional to the average value, the transmission rate control method using the error correction packet according to claim 1 or 2 having any one value of the preset value . The error correction packet, the transmission rate control method using the error correction packet according to any one of claims 1 to 3 is a FEC packet. The transmission rate control method using an error correction packet according to any one of claims 1 to 4, wherein feedback information about the first packet group and feedback information about the second packet group are provided through RTCP. A communication device that transmits a packet group in which a data packet and an error correction packet are configured at a predetermined ratio to a receiving device,
A receiving unit that receives feedback information about the first packet group from the receiving device and receives feedback information about the second packet group from the receiving device for a threshold time;
When the overall packet loss rate included in the feedback information related to the first packet group is equal to or greater than a threshold, the second packet group in which the ratio of error correction packets is increased from the first packet group is transmitted to the receiving device;
When the average value of the data packet loss rates included in the feedback information regarding the second packet group received during the threshold time is equal to or greater than the data packet loss rate included in the feedback information regarding the first packet group. A control unit for reducing the transmission rate,
The total packet loss rate included in the feedback information is calculated by the receiving apparatus using the data packet and error correction packet included in the received packet group and the ratio of the total packet received and the lost packet. And
The data packet loss rate included in the feedback information is calculated based on the data packet lost in the data packet included in the packet group by using the error correction packet included in the received packet group. Calculated by the restored result,
A communication device characterized by the above . The increase amount of the ratio of error correction packets included in the second packet group is either a value proportional to the total packet loss rate included in the feedback information regarding the first packet group or a preset value. The communication apparatus according to claim 6 , wherein the communication apparatus has one value. The communication apparatus according to claim 6 , wherein the amount of decrease in the transmission rate has any one of a value proportional to the average value and a preset value. The communication apparatus according to claim 6 , wherein the error correction packet is an FEC packet. The communication apparatus according to any one of claims 6 to 9, wherein feedback information about the first packet group and feedback information about the second packet group are provided through RTCP.

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