JP4687538B2 - Receiving device, transmitting device, and communication method therefor - Google Patents

Description

  The present invention relates to a receiving device, a transmitting device, and a communication method thereof for communicating hierarchically encoded data.

  Conventionally, as this communication method, for example, there is a method described in Patent Document 1.

  That is, in a system in which the transmission device 11 and the reception device 12 communicate via an external network, the transmission device 11 packetizes a plurality of layers of hierarchically encoded data and transmits the packet to the reception device 12 in units of layers. . The receiving device 12 transmits response information including the packet transmission time and the ID of the lost packet to the transmitting device. Then, the transmission device 11 calculates an optimal transmission rate according to the response information from the reception device 12, and sets the number of transmission packets based on the transmission rate. As a result, useless packet transmission can be eliminated, and communication efficiency can be improved.

The transmission rate control used at this time is TFRC (TCP FriendlyRate).
Control, RFC 3448) technology.

  This TFRC technique estimates and controls a transmission rate (X) that can share a bandwidth fairly with TCP based on a loss event rate (p) and a round trip time (R). Specifically, the transmission rate (X) is estimated by the following (Equation 1).

Here, R: round trip time (seconds), p: loss event rate, s: packet size (bytes), b: TCP acknowledgment unit, T_RTO: TCP timeout value (= 4 × R).
Note that the round trip time used in (Equation 1) is obtained from the transmission source transmission time included in the response information and the time when the transmission apparatus receives the response information packet.

  In transmission rate control using TFRC, the transmission apparatus performs transmission rate estimation using (Equation 1) or when notification of occurrence of packet loss is received. In addition, the receiving apparatus notifies the loss generated in a plurality of packets at once for each layer.

  FIG. 10 is a diagram illustrating response control when a conventional receiver receives hierarchically encoded data.

In FIG. 10, the data flow is divided into three layers from the basic layer to the extended two layers, and when there is a packet loss, the receiving apparatus collectively transmits response information (NACK) for each layer.
JP 2004-193992 A (pages 9-15, FIG. 3) TFRC (TCP Friendly Rate Control Specification), RFC 3448), Internet <URL: http://www.faqs.org/rfcs/rfc3448.html>

  However, in the conventional method, since the receiving device notifies the transmitting device of loss information for each layer, there is a problem that a control signal corresponding to a multiple of the number of layers flows over the network and the bandwidth is wasted. Was. Furthermore, the conventional transmission apparatus has a problem that it takes a very large load to receive a large amount of control signals from the reception apparatus and calculate the transmission rate.

  The present invention has been made to solve the above-described conventional problems. The object of the present invention is to suppress the consumption of the network bandwidth due to the response information of the receiving device in the transmission rate control of the hierarchical coded data communication, and An object of the present invention is to provide a communication method that reduces the load for performing transmission rate control.

  The receiving apparatus of the present invention streams hierarchically encoded data from the transmitting apparatus. In particular, the receiving apparatus of the present invention includes a packet receiving unit, a packet loss calculating unit, a reception state recording unit, an aggregate response information generating unit, and a packet transmitting unit. The packet receiving unit receives a hierarchically encoded data packet, and the packet loss calculating unit detects a missing or abnormal packet for each layer and calculates a packet loss rate. The reception band calculation unit counts packets received for each layer and calculates the reception band. The reception state recording unit calculates the packet loss rate calculated by the packet loss calculation unit and the reception band calculation unit. The reception status information including the received reception band is recorded. Further, the aggregate response information generation unit aggregates the reception status information of all layers recorded in the reception status recording unit into one response information, and the packet transmission unit generates response information generated by the response information generation unit. Is transmitted to the transmitter.

  As a result, the receiving device only has to create response information in which all hierarchies are combined into one, so that the response information creation load can be reduced. Further, since response information packets flowing on the network can be reduced as compared with the conventional case, the load on the network can be reduced.

  Further, in the receiving device of the present invention, the aggregate response information generation unit calculates an average value of packet loss rates of all layers for each predetermined time, for each predetermined number of data flows, or for each predetermined data amount, and The aggregated reception state information is generated by adding up the received data amounts of all layers from the previous aggregation to the present time.

  Thereby, the receiving apparatus can collect response information regularly or for every predetermined data amount.

  In the receiving apparatus of the present invention, the aggregate response information generation unit weights each layer and calculates an average value of the packet loss rate.

  Thereby, the receiving device can generate response information according to the importance of the hierarchy.

  In addition, when there is a packet loss or abnormality in the basic layer of the hierarchy, in the reception apparatus of the present invention, the aggregate response information generation unit includes the packet loss rate of the basic layer in the reception state information aggregated. Further, when there is no packet loss or abnormality in the base layer, the reception state information aggregated by weighting layers other than the base layer is calculated.

  As a result, the receiving apparatus can notify the transmitting apparatus of control of the transmission layer that guarantees reception of the base layer.

  The receiving apparatus of the present invention further includes a communication delay measuring unit and a response timing detecting unit. The communication delay measuring unit records the packet round trip time described in the received packet of each layer in the reception state recording unit for each layer. The response timing detection unit averages the packet round-trip required time recorded in the reception state recording unit and updates the obtained value as the predetermined period when the predetermined time set last time has passed since the previous transmission of the response information. To do.

  Thus, when the response information is transmitted every predetermined time, the receiving device can update the predetermined time according to the reception state.

  In addition, the receiving apparatus of the present invention further includes a priority policy setting unit that specifies a hierarchy combination policy for receiving a data flow of hierarchically encoded data from the transmitting apparatus. Then, the packet transmission unit transmits the policy to the transmission device.

Thereby, the receiving apparatus can request the transmitting apparatus to prioritize an object such as content preferred by the user or to prioritize the relationship between objects.
The receiving apparatus of the present invention determines the weight set by the aggregate response information generation unit based on the reciprocal of the reception band recorded in the reception status recording unit.

  As a result, the receiving apparatus can request the transmitting apparatus to control the transmission rate with an emphasis on a smaller reception band.

  The transmission apparatus of the present invention includes an object encoding unit, a packet transmission unit, a packet reception unit, a receiver band estimation unit, a flow combination determination unit, and a hierarchical delivery setting unit. The object encoding unit hierarchically encodes the content data, and the packet transmission unit transmits the encoded data as a packet.

  The packet receiving unit receives response information transmitted from the receiving device that has received the packet. The receiver band estimation unit includes packet loss information, reception band information, and response band information described in the response information. The transmission rate suitable for the receivable band of the receiving device is estimated based on the packet round-trip required time between itself and the receiving device. Further, the flow combination determining unit determines a data flow combination of hierarchically encoded data corresponding to the estimated transmission rate, and the hierarchical distribution setting unit groups receiving devices to be distributed for each data flow. The identification information of the corresponding receiving device is set in the destination list.

  Thereby, the transmission device can control the transmission rate based on the response information from the reception device.

  In the transmission apparatus of the present invention, the receiver band estimation unit estimates the transmission rate in accordance with TFRC (TCP Friendly Rate Control).

  The transmission apparatus of the present invention further includes a rate candidate recording unit that records the transmission rate when all data flows are combined. Then, the flow combination determination unit selects a transmission rate that minimizes the vacant bandwidth at the transmission rate estimated by the receiving apparatus from the rate candidate recording unit.

  Thereby, the transmission device can perform transmission using the bandwidth of the reception device most efficiently when changing the transmission rate to the reception device.

  In addition, the transmission device of the present invention further includes a priority policy management unit that records a transmission rate in which data flows are combined in accordance with a priority policy for a combination of data flows requested from the reception device in a rate candidate recording unit.

  Thereby, the transmission apparatus can perform transmission rate control that satisfies the request of the reception apparatus.

  The communication method of the present invention is performed as follows. That is, when the transmitting device transmits a packet of hierarchically encoded data, the receiving device receives the packet, detects packet loss or abnormality for each layer, calculates and records the packet loss rate. Or count the packets received for each layer, calculate the reception bandwidth, and record it. Then, the receiving apparatus aggregates the recorded reception state information including the packet loss rate and the reception band of all layers into one response information, and transmits the response information to the transmitting apparatus. The transmitting device receives the response information, and is suitable for the receivable bandwidth of the receiving device based on the packet loss information described in it, the received bandwidth information, and the packet round trip time between itself and the receiving device. Estimate the transmission rate. Then, the transmission apparatus determines a data flow combination of hierarchically encoded data corresponding to the estimated transmission rate.

  In the communication method of the present invention, the response information is aggregated every predetermined time, every predetermined number of data flows, or every predetermined amount of data, and the average value of packet loss rates of all layers and the previous time This is a process of calculating the sum of received data amounts of all layers from the aggregation to the current time.

  In the communication method of the present invention, the receiving device transmits a priority policy for determining a combination of data flows to the transmitting device, and the transmitting device determines a data flow combination according to the received priority policy.

  ADVANTAGE OF THE INVENTION According to this invention, consumption of the network band by the response of a control signal can be suppressed in hierarchy coding data communication. Further, the transmission apparatus can reduce the load for controlling the transmission rate of the hierarchically encoded data.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a communication system according to the present invention.

  In FIG. 1, a transmission apparatus 10 and a reception apparatus 20 can communicate with each other via an external network 30 such as the Internet, and the reception apparatus 20 streams video, audio data, and the like from the transmission apparatus.

  The transmission apparatus 10 determines object encoding units 300 to 302 that hierarchically encode objects such as video and audio received from the media 1 (400) to the medium N (402), and an object layer to be distributed for each reception apparatus. And a communication control unit 100 that transmits a multicast packet and an explicit multicast (hereinafter referred to as “XCAST”) packet to the receiving device.

  The receiving device 20 receives a packet addressed to itself, extracts a communication control unit 500 for extracting object data, object decoding units 700 to 702 for decoding the extracted object data, and combines the decoded objects. And a scene composition unit 800 for outputting to the playback device 900.

  In XCAST, when a packet is delivered to a plurality of receiving apparatuses, the transmitting apparatus creates a destination list in the packet and transmits it to the first node in the destination list.

  FIG. 9 is a diagram illustrating the format of an XCAST packet. The XCAST performs communication using IPv6 as an IP address.

  In FIG. 9, an XCAST header (XCASTHdr) 1401 includes an IPv6 header (IPv6Hdr) 1402 and a routing header (RoutingHdr) 1403. The source address 1404 of the IPv6 header 1402 describes the IP address of the packet source node, and the destination address 1405 describes a multicast address indicating XCAST.

  The routing header 1403 describes all destination addresses 0 to n (1407) and destination ports (Port) 0 to n (1408), which are multicast transmission destinations. In the destination bitmap 1406, a bit is designated corresponding to the destination node, and an undelivered destination node ('1' is set) and a delivered destination node ('0') are set. Is clearly stated. In the following description, the destination bitmap 1406 and the destination address 1407 are collectively referred to as a “destination list”.

  When the node corresponding to XCAST receives the packet, it refers to its route table and outputs the packet to the first undelivered node in the destination list. At this time, the node appropriately duplicates the packet, and corrects the destination bitmap 1406 so that only the bit corresponding to the undelivered destination node becomes “1”. Upon receiving this, the terminal that is the destination node sets the bit corresponding to itself in the destination bitmap 1406 to “0” for delivery, and transmits the packet to the terminal that is an undelivered destination node.

  As a result, even if an IP multicast address is not used, one packet is sequentially transmitted to a plurality of terminals, so that the same data can be transmitted to terminals of a plurality of destination groups as in the case of IP multicast.

  FIG. 2 is a diagram illustrating a configuration of the communication control unit 100 of the transmission apparatus 10 according to the present invention.

  In FIG. 2, a packet transmission unit 103 generates and transmits a packet of a data flow related to each delivery group using a multipoint delivery method such as multicast or XCAST.

  Note that the packet transmission unit 103 can perform unicast in addition to multicast. The packet receiving unit 102 receives control signals such as response information and a bandwidth request for a communication status inquiry from the receiving device.

  Further, the rate control unit 101 performs control to estimate a network communicable band from response information from the receiving apparatus or to change a transmission rate based on a band request from the receiving apparatus. The rate control unit 101 further includes a receiver band estimation unit 1011, a flow combination determination unit 1012, a rate candidate recording unit 1013, and a hierarchical delivery setting unit 1014.

  The receiver band estimation unit 1011 calculates and estimates a transmission rate suitable for the receiving apparatus using (Equation 1) based on the response information and the band request received from the receiving apparatus.

  The flow combination determination unit 1012 can transmit a data flow (for example, a layer-encoded layer, object, or media) that can be transmitted by the transmission apparatus with respect to the band (transmission rate) estimated by the receiver band estimation unit 1011. Is determined.

  The rate candidate recording unit 1013 records a transmission rate candidate set based on different combinations of various data flows.

  The hierarchical delivery setting unit 1014 adds or deletes the identification information of the receiving device to the delivery list of the delivery group corresponding to the data flow combination newly determined by the flow combination determination unit 1012. This delivery list is used in XCAST, and the delivery destination node transfers the packet received by itself to the nodes described in this delivery list.

  Here, the rate candidate recording unit 1013 and the flow combination determining unit 1012 will be described below using specific object data.

  FIG. 4 is a diagram showing a combination of hierarchically encoded data and hierarchically encoded data distributed to each receiving device.

  In FIG. 4, objects 1, 2, and 3 are each hierarchized into three hierarchies. In each hierarchically encoded data, a necessary band is designated.

  Table 1 shows the transmission rate when the hierarchical data of these objects are combined, and is recorded in the rate candidate recording unit 1013. For example, Table 1 shows that a reception band of 290 kbps is required to receive the base layer of all objects and the extended one layer of object 3.

  Then, the flow combination determination unit 1012 refers to the rate candidate recording unit 1013 and selects a layer combination so that the estimated bandwidth of the receiving device can be used effectively.

  FIG. 4 shows layers selected by the flow combination determination unit 1012 when the receiving apparatuses 1 to 4 can use bands of 480 kbps, 410 kbps, 315 kbps, and 650 kbps, respectively.

  In other words, the flow combination determination unit 1012 uses the base layer of the object A, the base layer of the object B and the extension 1 layer, and the base layer of the object C as hierarchically encoded data that can be distributed within 480 kbps, which is the usable bandwidth of the receiving device 1. , Extended 1 layer, extended 2 layer are selected. Similarly, the flow combination determination unit 1012 uses the base layer of the object A, the base layer of the object B, the extension 1 layer, the extension 2 layer, the base layer of the object C, and the extension 1 as the hierarchically encoded data that can be delivered to the receiving device 2. Select a layer.

  Further, the flow combination determination unit 1012 selects the base layer of the object A, the extended 1 layer, the base layer of the object B, and the base layer of the object C as the hierarchically encoded data that can be delivered to the receiving device 3. In addition, the flow combination determination unit 1012 includes, as hierarchically encoded data that can be delivered to the receiving device 4, a basic layer of Object A, an extended 1 layer, an extended 2 layer, a basic layer of Object B, an extended 1 layer, an extended 2 layer, an object C base layer and extended 1 layer are selected.

  The operation and action of the transmission apparatus configured as described above will be described below.

  FIG. 5 is a flowchart for explaining the operation of the transmission apparatus.

  In FIG. 5, first, the flow combination determination unit 1012 determines a data flow combination that can be delivered with an initial value of a transmission rate defined in advance in the receiving apparatus, and notifies the hierarchical delivery setting unit 1014 (step S501). .

  In response to this, the hierarchical delivery setting unit 1014 extracts a destination to which object data is delivered for each layer, and describes the extracted identification information of the receiving device in the delivery list. For example, in the case of the combination shown in FIG. 4, all of the receiving devices 1 to 4 are described in the base layer object data destination list, and the receiving device 3 Only 4 is described (step S502).

  Next, the packet transmitting unit 103 transmits the packet to the first receiving device in the destination list at the transmission rate set in the layer object data (step S503).

  Next, the flow combination determination unit 1012 checks whether or not transmission of all object data has been completed (step S504). If transmission has been completed, the transmission process ends.

  On the other hand, when the flow combination determination unit 1012 has not completed transmission of object data, the packet reception unit 102 receives a control packet in which response information such as RTT and packet loss rate is described from the reception device 20. Then, the receiver band estimation unit 1011 calculates the transmission rate of the receiving apparatus that has transmitted the response information (step S504).

  Next, the flow combination determination unit 1012 refers to the rate candidate recording unit 1013, and selects a layer combination that matches the newly estimated reception band (step S505).

  Thereafter, the process returns to step S502, and an XCAST packet is created with the updated layer combination and transmitted to the receiving apparatus.

  The above is the description of the configuration and operation of the transmission apparatus of the present invention.

  Next, the receiving apparatus of the present invention will be described.

  FIG. 3 is a diagram illustrating a configuration of the communication control unit 500 of the receiving apparatus according to the present embodiment.

  In FIG. 3, a packet receiving unit 602 receives a packet such as a data flow or a control signal transmitted from a transmitting device, and sends data from which the header is removed to the reception state management unit 601.

  The packet transmission unit 603 packetizes the response information generated by the reception state management unit 601 and transmits the packet to the transmission device.

  The response timing detection unit 604 measures timing for transmitting response information to the transmission device.

  The reception state management unit 601 calculates the reception state of the data flow and generates response information. The reception state management unit 601 further includes a communication delay measurement unit 6011, a packet loss calculation unit 6012, a reception band calculation unit 6013, a reception state recording unit 6014, and an aggregate response information generation unit 6015.

  The communication delay measuring unit 6011 extracts the transmission time of the received packet and records it in the reception state recording unit 6014. The packet loss calculation unit 6012 detects packet loss from missing serial numbers of received packets, calculates a loss rate, and records it in the reception state recording unit 6014. The loss rate calculation method uses a method defined by TFRC.

  The reception band calculation unit 6013 measures the amount of data received from the previous response time to the present, calculates the band that can be received, and records the reception band in the reception state recording unit 6014. .

  Table 2 is a table showing reception state information recorded by the reception state recording unit 6014. The flow ID indicates each layer that is hierarchically encoded, the flow ID 1 indicates the basic layer, the flow ID 2 indicates the extended 1 layer, and the flow ID 3 indicates the extended 2 layer. Further, the passage of the update time indicates the time when the RTT, the packet loss rate, and the reception band are updated.

  The aggregate response information generation unit 6015 aggregates the packet loss rate and reception band information of each layer recorded in the reception state recording unit 6014 into one for every predetermined time.

(Expression 2) is an expression for aggregating packet loss rates, and an average value of packet loss rates of all layers is obtained.

  (Expression 3) is an expression for aggregating the reception bands, and the sum of the reception bands of all layers is obtained.

  In addition, (Equation 2) and (Equation 3) treat each layer equally, but since the importance of scene reproduction differs for each layer, it is more preferable to weight each layer. For example, as shown in Table 3, each layer is given a weight.

  A calculation formula for aggregating packet loss rates at this time is shown in (Formula 4).

The weighting is determined by the transmission device and notified to the reception device.
In addition to the above weighting, if there is packet loss in the base layer, use the packet loss rate of the base layer and the reception bandwidth as response information, and only when there is no packet loss in the base layer. It is also possible to calculate the response information aggregated by the above (Formula 3) and (Formula 4) by weighting other layers.

  The operation and action of the receiving apparatus configured as described above will be described below.

  FIG. 6 is a flowchart for explaining the operation of the receiving apparatus.

  In FIG. 6, first, when the packet reception unit 602 receives a plurality of hierarchically encoded data (S601), the communication delay measurement unit 6011, the packet loss calculation unit 6012, and the reception bandwidth calculation unit 6013 of the reception state management unit 601 receive them. The reception state is recorded in the reception state recording unit 6014 from the packet information (step S602).

  Next, the response timing detection unit 604 compares the elapsed time from the previous response to the present with the average period of the elapsed time from the time recorded in the RTT of each layer of the reception state storage unit 6014 to the present. (Step S603). When the elapsed time from the previous response is longer, the response timing detection unit 604 instructs the aggregate response information generation unit 6015 to generate response information (Yes in step S603).

  In response, the aggregate response information generation unit 6015 generates response information in which the packet loss rate and the reception band recorded in the reception status recording unit 6014 are aggregated, and sends the response information to the packet transmission unit 603 (step S604). Further, the aggregate response information generation unit 6015 copies the RTT recorded immediately before receiving the instruction from the response timing detection unit 604 to the RTT in the packet header.

  In response to this, the packet transmission unit 603 transmits a packet describing the response information to the transmission device (step S605), and the process returns to step S601.

  On the other hand, if the elapsed time from the previous response is not longer in step S603, the process returns to step S601.

  The above is the description of the configuration and operation of the transmission apparatus of the present invention.

  As described above, according to the present embodiment, the receiving apparatus only needs to transmit the response information for transmission rate control for the received layer encoded data, once for all the layers, once every predetermined time. The state is shown in FIG.

  In FIG. 7, response information (NACK) is a response that collectively includes response information of all layers when packet loss occurs.

  As described above, the response information generation load of the receiving apparatus can be reduced as compared with the response state illustrated in FIG. 10. Further, the number of packets in which response information flowing on the network is described can be reduced to a fraction of the number of layers, and network congestion can be avoided. Furthermore, the transmission apparatus can perform the transmission rate control processing performed when receiving the response information from the reception apparatus all at once, and can reduce the load of transmission rate control.

  In the present embodiment, the response information is generated once every predetermined time. However, the present invention is not limited to this, and the response information can be aggregated for every predetermined number of data flows or every predetermined amount of data.

  In addition, the transmission device notifies the reception device of the transmission time in order to measure the packet round-trip time, but in addition to all the reception devices receiving the same data flow as the transmission device itself It is also possible to select a maximum value (GRTT) from a plurality of measured RTTs and notify the receiving apparatus. In this case, the receiving apparatus extracts the GRTT from the received packet, records it in the reception state recording unit for each layer, and sets the averaged time as the interval of the aggregation process.

(Embodiment 2)
FIG. 8 is a diagram illustrating a configuration of a transmission device and a reception device in the present embodiment.
The transmission apparatus according to the present embodiment is different from that according to the first embodiment in that it includes a priority policy management unit.

  The priority policy management unit 200 manages which of the following three methods is selected, and creates a transmission rate table suitable for each priority policy in the rate candidate recording unit 1013.

  As the priority policy, there are the following three methods.

  The first priority method is a method that uses the reception band most effectively, the second priority method is a method that prioritizes the user's preference, and the third priority method is each layer of hierarchically encoded data. This is a method of giving priority to the relationship strength between objects. It should be noted that the priority policy is notified from the receiving device, and when there is no notification, the first priority method is selected.

  The first priority method is the method shown in Embodiment 1, and an example of the transmission rate table is as shown in Table 1.

  An example of the transmission rate table of the second priority method is shown in Table 4. This table is generated by the priority policy management unit 200 when the receiving apparatus requests that the object 2 be prioritized. That is, when the estimated reception band of the receiving apparatus is smaller than 335 kbps, the combination of only the base layer of all objects (215 kbps), the combination of all the basic layers and the extended one layer of object 2 (255 kbps), One of a combination of the base layer and the extension 1 layer of the object 2 and the extension 2 layer (335 kbps) is selected. In Table 4, when the estimated reception band of the receiving apparatus is larger than 335 kbps, a combination of layers that can use the reception band most effectively is selected.

  An example of the transmission rate table of the third priority method is shown in Table 5. This table is generated by the priority policy management unit 200 when the receiving apparatus requests to prioritize the relationship between the objects 2 and 3. That is, when the estimated reception band of the receiving apparatus is smaller than 560 kbps, the combination of only the base layers of all objects (215 kbps), the combination of all the basic layers and the extended one layer of object 2 (255 kbps), A combination of the base layer and the extended layer of the object 3 (290 kbps), a combination of the extended layer of all the basic layers and the object 2 and the extended layer of the object 3 (330 kbps), and an extended layer of all the basic layers and the object 2 And a combination of the extended 2 layer and the extended layer of the object 3 (410 kbps), a combination of all the basic layers, the extended layer of the object 2, the extended 2 layer, the extended layer of the object 3 and the extended 2 layer (560 kbps). Some are selected. In Table 5, when the estimated reception band of the receiving apparatus is larger than 560 kbps, a combination of layers that can use the reception band most effectively is selected.

The operation of the transmission apparatus configured as described above will be described below.
First, when receiving a request for a priority policy from the receiving device, the priority policy management unit 200 creates a transmission rate table in the rate candidate recording unit 1013 according to the priority policy.

  Next, the flow combination determination unit 1012 selects a transmission rate table corresponding to the priority policy notified from the priority policy management unit 200 from the rate candidate recording unit 1013, and based on the transmission rate table, the initial reception of the receiving device Determine the combination of data flow layers according to bandwidth.

  Thereafter, the operations in steps S502 to S506 of the first embodiment are performed.

  The above is the description of the configuration and operation of the transmission apparatus according to this embodiment.

  Next, the receiving apparatus in this embodiment will be described.

  In FIG. 8, the receiving apparatus according to the present embodiment is different from that according to the first embodiment in that it includes a priority policy setting unit 600.

  The priority policy setting unit 600 is used by the user to set preferences and object relationships that the user wants to prioritize in the scene reproduction, that is, the priority policy, and has an interface for the user to set them.

  The priority policy setting unit 600 transmits the priority policy set by the user to the transmission device via the packet transmission unit 503. The request for the priority policy to the transmitting apparatus is preferably made before the start of content reception. Other operations are the same as those in the first embodiment.

  As described above, according to the transmission device and the reception device in the present embodiment, it is possible to receive object data that matches the user's preference from the transmission device, even if a change occurs in the reception band of the reception device, From the transmission device, it is possible to receive object data that can be received in the reception band and that best suits the user's preference.

  INDUSTRIAL APPLICABILITY The present invention is useful for a transmission device, a reception device, and the like that perform hierarchical encoded data communication, and is suitable for transmission rate control using TFRC.

The figure which shows the structure of the communication system in Embodiment 1 of this invention. The figure which shows the structure of the communication control part of the transmitter in Embodiment 1 of this invention. The figure which shows the structure of the communication control part of the receiver in Embodiment 1 of this invention. The figure which showed the combination of the hierarchy coding data in Embodiment 1 of this invention, and the hierarchy coding data delivered to a receiver. FIG. 3 is a flowchart for explaining the operation of the transmission apparatus according to Embodiment 1 of the present invention. FIG. 3 is a flowchart for explaining the operation of the receiving apparatus according to Embodiment 1 of the present invention. The figure which shows the state which transmits the response information which the receiver in Embodiment 1 of this invention performs The figure which shows the structure of the communication system in Embodiment 2 of this invention. The figure which shows the format of the packet of the conventional XCAST The figure which shows the state which transmits the response information which the conventional receiver performs

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transmission apparatus 20 Reception apparatus 30 External network 100 Communication control part 101 Rate control part 102 Packet reception part 103 Packet transmission part 200 Priority policy management part 300 thru | or 302 Object encoding part 400 thru | or 402 Media 500 Communication control part 600 Priority policy setting part 601 Reception state management unit 602 Packet reception unit 603 Packet transmission unit 604 Response timing detection unit 700 to 702 Object decoding unit 800 Scene synthesis unit 900 Playback device 1011 Receiver bandwidth estimation unit 1012 Flow combination determination unit 1013 Rate candidate recording unit 1014 Hierarchy Delivery setting unit 6011 communication delay measurement unit 6012 packet loss calculation unit 6013 reception band calculation unit 6014 reception state recording unit 6015 aggregate response information generation unit

Claims (16)

A packet reception unit that receives hierarchically encoded data that is hierarchically encoded into one or more layers and is transmitted from a transmission device using different packets in each layer;
A calculation unit that detects communication quality for each of the one or more layers based on a reception status of the packet;
An aggregate response information generation unit that aggregates communication quality for all layers into one response information;
A packet transmitter that transmits the response information to the transmitter;
A communication device. A packet reception unit that receives hierarchically encoded data that is hierarchically encoded into one or more layers and is transmitted from a transmission device using different packets in each layer;
A detection unit for detecting packet loss based on a sequence number of the received packet;
An aggregate response information generating unit that aggregates packet loss for all layers generated in one interval period in all layers into one NACK information;
A packet transmission unit for transmitting the NACK information to the transmission device;
A communication device. A receiving apparatus that streams hierarchically encoded data that has been hierarchically encoded into one or more hierarchies and transmitted from a transmitting apparatus using different packets in each hierarchy ,
A packet receiver for receiving the hierarchically encoded data packet;
A packet loss calculation unit that detects the loss or abnormality of the received packet for each layer and calculates the packet loss rate;
A reception bandwidth calculation unit that counts packets received for each layer and calculates a reception bandwidth;
A reception state recording unit that records reception state information including the packet loss rate calculated by the packet loss calculation unit and the reception band calculated by the reception band calculation unit;
An aggregate response information generation unit that aggregates reception status information of all layers recorded in the reception status recording unit into one response information;
And a packet transmission unit configured to transmit the response information generated by the aggregate response information generation unit to the transmission device. The aggregate response information generation unit calculates an average value of packet loss rates of all layers for every predetermined time, for each predetermined number of data flows, or for each predetermined data amount, and for all the data from the previous aggregation to the present time. The receiving apparatus according to claim 3 , wherein the sum of the received data amounts of the layers is used as aggregated reception state information. The receiving apparatus according to claim 4 , wherein the aggregate response information generation unit calculates an average value of the packet loss rates by weighting each layer. When there is packet loss or abnormality in the base layer of the hierarchy, the aggregate response information generation unit includes the packet loss rate of the base layer in the reception state information aggregated, and there is no packet loss or abnormality in the base layer, The receiving apparatus according to claim 5 , wherein reception state information that is weighted and aggregated to a layer other than a layer is calculated. A communication delay measuring unit that records a packet round-trip required time described in a received packet of each layer in the reception state recording unit for each layer;
A response timing detection unit that averages the packet round-trip required time recorded in the reception status recording unit and updates the obtained value as the predetermined period when a predetermined time set last time has passed since the previous transmission of the response information The receiving device according to claim 4 , further comprising: A priority policy setting unit for specifying a combination policy of layers for receiving a data flow of layer encoded data from the transmission device;
The receiving device according to claim 4 , wherein the packet transmitting unit transmits the policy to a transmitting device. The receiving apparatus according to claim 5 , wherein the weighting set by the aggregate response information generation unit is determined based on an inverse number of a reception band recorded in the reception state recording unit. An object encoding unit that hierarchically encodes content data into one or more layers ;
A packet transmission unit that transmits encoded data using different packets in each layer, and transmits a weight of each layer of the one or more layers ;
A packet receiving unit that receives the response information generated by the receiving device that has received the packet using the weighting, the communication quality of all layers being aggregated into one response information ;
Estimate the transmission rate suitable for the receivable bandwidth of the receiving device based on the packet loss information, the received bandwidth information, and the packet round trip time between itself and the receiving device described in the response information A receiver band estimation unit to
A flow combination determination unit for determining a data flow combination of hierarchically encoded data corresponding to the estimated transmission rate;
A transmission apparatus comprising: a grouping delivery setting unit that groups the reception apparatuses to be delivered for each data flow and sets identification information of the corresponding reception apparatus in a destination list. The transmission apparatus according to claim 10 , wherein the receiver band estimation unit estimates the transmission rate according to TFRC (TCP Friendly Rate Control). A rate candidate recording unit that records a transmission rate when all the data flows are combined;
The transmission device according to claim 10 , wherein the flow combination determination unit selects a transmission rate at which a vacant bandwidth is minimized at the transmission rate estimated by the reception device from the rate candidate recording unit. Transmitting apparatus according to claim 1 2, further comprising a priority policy management unit for recording a transmission rate that combines the data flow according to the priority policy combination of data flow requested by the receiving device to the rate candidate recording unit. A step of transmitting a packet of data that is hierarchically encoded into one or more layers and subjected to layer encoding using a different packet in each layer ;
Receiving the packet, detecting missing or abnormal packet for each layer, calculating a packet loss rate, and recording,
A reception device that counts packets received for each layer, calculates a reception band, and records;
The receiving device aggregates the received state information including the packet loss rate and the reception band of all layers recorded into one response information;
A receiving device transmitting the aggregated response information to a transmitting device;
The transmission device receives the response information, and receives the reception device based on the packet loss information and the reception band information described in the response information and the packet round-trip required time between itself and the reception device. Estimating a transmission rate suitable for the possible bandwidth;
Determining a data flow combination of hierarchically encoded data corresponding to the estimated transmission rate. The aggregation of the response information is performed every predetermined time, every predetermined number of data flows, or every predetermined amount of data, and the average value of the packet loss rate of all layers and the total of all layers from the previous aggregation to the present time. communication method according to claim 1 4, which is a process of calculating the sum of the amount of received data. The receiving device transmitting a priority policy for determining a combination of the data flows to a transmitting device;
The communication method according to claim 15 , wherein the transmission device receives the priority policy and determines the combination of the data flows according to the priority policy.

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