JP2013207431A - Transmission terminal device, data transmission and reception system, data transmission method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission terminal device, a data transmission and reception system, a data transmission method, and a program capable of improving the reproduction quality of multimedia data such as moving images, sounds.SOLUTION: A copy packet generator 105D generates copy packets. An order determination unit 105E determines the read-out timing (order) of the copy packets. A controller 105 controls an RTP processor 105G to read the copy packets in accordance with the read-out timing (order) of the copy packets determined by the order determination unit 105E.

Description

  The present invention relates to a transmission terminal device, a data transmission / reception system, a data transmission method, and a program.

  The use of real-time applications such as VoIP (Voice Over Internet Protocol) and data streams for transmitting and receiving data such as video and audio via an IP (Internet Protocol) network is increasing. When transmitting and receiving data in real time, RTP (Real-time Transport Protocol) is used. In order to place importance on real-time properties, UDP (User Datagram Protocol) is usually used as a transport layer.

  Unlike UDP (Transmission Control Protocol) having an error correction function such as retransmitting lost packet data by performing packet sequence check, this UDP does not perform packet data delivery confirmation. Therefore, when communication is performed via an unreliable IP network such as microwave radio communication, there is a problem in that the packet drop rate in the packet transmission process increases and the quality of video or audio deteriorates. is there.

  As a solution to this problem, for example, in Patent Document 1, when the transmission device receives a signal indicating that the packet data transmitted from the reception device could not be received, a plurality of the same packet data are continuously transmitted thereafter. Then, a method for transmitting to the receiving apparatus has been proposed.

  Further, for example, in Patent Document 2, when it is determined that a transmission error of an RTP packet has occurred, the payload included in the RTP packet immediately before the transmission error has occurred so as to be equal to or smaller than the jitter buffer size provided in the receiving device. A method has been proposed in which data (actual data) and data to be transmitted next are combined and an RTP packet including the combined data is transmitted to a receiving apparatus at the next RTP packet transmission timing.

  In the method proposed in Patent Document 2, the actual data included in the RTP packet that failed to be transmitted is combined with the data to be transmitted next, and the RTP packet including the combined data is converted into the next RTP packet. Since transmission is performed at the transmission timing, it is possible to retransmit the actual data that failed to be transmitted without increasing the load on the CPU and the network.

JP 2004-350252 A JP 2009-260719 A

  However, in the method proposed in Patent Document 1, a plurality of the same packet data is continuously transmitted, and therefore, if a burst error occurs, all the same packet data may be lost. .

  In addition, in the method proposed in Patent Document 2, when the transmission of the RTP packet fails, taking into consideration the state of the IP network, the transmission of the next RTP packet is not performed, instead of immediately transmitting the failed data. Send in time.

  However, since the transmission interval of RTP packets is usually very short, it is unlikely that the state of the IP network is improved even if it is transmitted at the next transmission timing. For this reason, even if data that has failed to be transmitted is transmitted together with data to be transmitted next, there is a possibility that the packet will be lost again, which does not necessarily improve the quality of the moving image or audio.

  Further, in the method proposed in Patent Document 2, after receiving the notification of the transmission error of the RTP packet, the data that failed to be transmitted is sent together with the data to be transmitted next. Can not be absorbed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a transmission terminal device, a data transmission / reception system, a data transmission method, and a program capable of improving the reproduction quality of multimedia data.

In order to achieve the above object, a transmission terminal apparatus according to the first aspect of the present invention provides:
A communication unit that transmits a packet including multimedia data to a receiving terminal device via a network;
A duplicate packet generator for generating a duplicate of the packet;
At least one other packet is inserted between the transmission order of the replication source packet and the transmission order of the replicated packet, and the replicated packet and the replication source packet are transmitted to the receiving terminal device. An order determination unit for determining the order;
In accordance with the order determined by the order determination unit, a control unit for controlling the timing of transmitting the duplicated packet and the original packet,
It is characterized by providing.

In addition, a communication with the receiving terminal device further comprises a missing rate acquisition unit that acquires a missing rate that is a rate at which packets transmitted to the receiving terminal device are lost in the propagation process,
The duplicate packet generation unit generates a number of copies of the packet according to the packet loss rate acquired by the loss rate acquisition unit;
It is good as well.

Further, the missing rate acquisition unit intermittently acquires the missing rate of the packet,
The order determination unit determines the order of transmitting the duplicated packet and the duplication source packet to the receiving terminal device each time the missing rate acquisition unit obtains the missing rate of the packet.
It is good as well.

Further, the apparatus further comprises a determination unit that determines whether or not the missing rate acquired this time by the missing rate acquisition unit has changed from the previously acquired missing rate,
Only when it is determined that there is a change in the missing rate, the order determination unit determines the order in which the duplicated packet and the duplicated source packet are transmitted to the receiving terminal device.
It is good as well.

A control table storage unit that stores in advance a replication number control table in which the packet loss rate and the packet replication number are associated;
With reference to the replication number control table, a packet replication number determination unit that determines the replication number of the packet from the deletion rate acquired by the deletion rate acquisition unit;
Further comprising
The duplicate packet generator generates duplicate packets for the number of replicas determined by the packet replica number determiner;
It is good as well.

Further, the communication apparatus further includes a maximum storable number calculating unit that calculates the maximum number of the packets that can be stored in a jitter buffer included in the receiving terminal device by communication with the receiving terminal device.
The order determination unit determines whether a difference between an order in which the last transmitted packet is transmitted and an order in which the first transmitted packet is transmitted among the copied packet and the original packet. Determining the transmission timing so as to be smaller than the maximum number calculated by the maximum storable number calculation unit;
It is good as well.

The order determining unit randomly determines the order of transmitting the duplicated packet and the duplication source packet to the receiving terminal device.
It is good as well.

Further, a maximum storable number calculating unit that calculates the maximum number of the packets that can be stored in a jitter buffer included in the receiving terminal device by communication with the receiving terminal device;
In order to specify the order of transmitting the duplicated packet and the duplication source packet to the receiving terminal device from the packet drop rate and the maximum number of packets that can be stored in the jitter buffer of the receiving terminal device An order specification table storage unit for storing the order specification table in advance,
Further comprising
The order determining unit refers to the order specifying table and replicates the packet from the packet loss rate acquired by the loss rate acquisition unit and the maximum number calculated by the maximum storable number calculation unit. Determining the order in which the received packet and the duplication source packet are transmitted to the receiving terminal device,
It is good as well.

In addition, transmission of multimedia data to the receiving terminal device is in real time.
It is good as well.

The network is a wireless network.
It is good as well.

In order to achieve the above object, a data transmission / reception system according to the second aspect of the present invention provides:
A data transmission / reception system comprising: a transmission terminal device that transmits multimedia data via a network; and a reception terminal device that receives multimedia data transmitted from the transmission terminal device,
The transmitting terminal device
A communication unit that transmits a packet including the multimedia data to the receiving terminal device via the network;
A duplicate packet generator for generating a duplicate of the packet;
At least one other packet is inserted between the transmission order of the replication source packet and the transmission order of the replicated packet, and the replicated packet and the replication source packet are transmitted to the receiving terminal device. An order determination unit for determining the order;
In accordance with the order determined by the order determination unit, the control unit for controlling the timing of transmitting the replicated packet and its replication source packet;
With
The receiving terminal device
A communication unit that receives the packet transmitted from the transmission terminal device;
A determination to determine whether a packet including multimedia data identical to the multimedia data included in the received packet is received before receiving the received packet each time the packet is received And
When it is determined by the determination unit that a packet including the same multimedia data has already been received, a control unit that deletes the received packet;
Comprising
It is characterized by that.

In order to achieve the above object, a data transmission method according to a third aspect of the present invention includes:
Generate duplicates of packets containing multimedia data,
Order in which at least one other packet is inserted between the transmission order of the duplication source packet and the duplication packet transmission order, and the duplication packet and the duplication source packet are transmitted to the receiving terminal device Decide
In accordance with the determined order, the duplicated packet and the duplication source packet are transmitted to the receiving terminal device.
It is characterized by that.

In order to achieve the above object, a program according to the fourth aspect of the present invention provides:
To a computer having a function of transmitting multimedia data to a receiving terminal device of a communication partner via a network,
Generating a copy of the packet containing the multimedia data;
At least one other packet is inserted between the transmission order of the replication source packet and the transmission order of the replicated packet, and the replicated packet and the replication source packet are transmitted to the receiving terminal device. Processing to determine the order;
In accordance with the determined order, a process of transmitting the duplicated packet and its original packet to the receiving terminal device;
Is executed.

  According to the present invention, it is possible to improve the reproduction quality of multimedia data such as moving images and sounds.

(A) is a figure which shows the structure of the data transmission / reception system in Embodiment 1. FIG. FIG. 2B is a functional block diagram illustrating a configuration of a transmission terminal device or a reception terminal device that configures the data transmission / reception system according to the first embodiment. 3 is a functional block diagram illustrating a configuration of a transmission terminal device in Embodiment 1. FIG. 4 is a functional block diagram illustrating a configuration of a storage unit included in a transmission terminal device in Embodiment 1. FIG. 4 is a functional block diagram illustrating a configuration of a control unit included in a transmission terminal device in Embodiment 1. FIG. 2 is a functional block diagram illustrating a configuration of a receiving terminal device in Embodiment 1. FIG. 3 is a functional block diagram illustrating a configuration of a storage unit included in the receiving terminal device in Embodiment 1. FIG. 3 is a functional block diagram illustrating a configuration of a control unit included in the reception terminal device in Embodiment 1. FIG. 6 is a diagram illustrating an example of a maximum storable number information table in the first embodiment. FIG. 6 is a diagram illustrating an example of a replication number control table in the first embodiment. FIG. It is a figure which shows the example of a structure of a RR packet. It is the figure which showed the read-out timing typically. FIG. 6 is a diagram illustrating a flowchart of a reading order determination process in the first embodiment. 6 is a diagram illustrating a flowchart of RTP packet reception processing in Embodiment 1. FIG. 6 is a diagram illustrating a flowchart of RR packet transmission processing in Embodiment 1. FIG. (A) thru | or (c) is a figure for demonstrating the reception process of the RTP packet in a receiving terminal device. 6 is a functional block diagram illustrating a configuration of a storage unit in Embodiment 2. FIG. It is a figure which shows the example of the order specific table in Embodiment 2. FIG. FIG. 10 is a functional block diagram illustrating a configuration of a control unit in a third embodiment. FIG. 10 is a diagram illustrating a flowchart of a reading order determination process in the third embodiment. FIG. 10 is a diagram illustrating a part of a flowchart of a reading order determination process in Modification 1; FIG. 10 is a diagram illustrating a part of a flowchart of a reading order determination process in Modification 2.

  A decoding apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1A is a block diagram showing the configuration of the data transmission / reception system 1. The digital communication system 1 according to the present embodiment includes a transmission terminal device 100 and a reception terminal device 200, and can transmit and receive data to and from each other via an IP network NW. As shown in FIG. 1B, the transmission terminal device 100 and the reception terminal device 200 are configured to include an input unit 001, an A / D002, a DSP003, an output unit 004, a storage unit 005, a control unit 006, and an operation. For example, it can be realized by a PC (Personal Computer), a mobile phone, a high-function mobile phone, a PDA (Personal Digital Assistants), an IP phone, an IP radio, and the like.

  The transmitting terminal device 100 can communicate with a plurality of receiving terminal devices 200 at the same time, but since each process is the same, the transmitting terminal device 100 is connected to one receiving terminal device 200 via the IP network NW. An example of performing data communication will be described below. Further, the transmission terminal device 100 functions as a reception terminal device, and conversely, the reception terminal device 200 functions as a transmission terminal device, but the transmission terminal device 100 functions as a transmission terminal device, and the reception terminal device 200 functions as a reception terminal device. Only the function of each functional unit when functioning will be described below.

  As shown in FIG. 2, the transmission terminal apparatus 100 includes an input unit 101, an A / D 102, a DSP 103, a storage unit 104, a control unit 105, a wireless communication unit 106, and the like.

  The input unit 101 includes an imaging element such as a charge coupled device (CCD) and a complementary metal oxide semiconductor image sensor (CMOS), a microphone, and the like, and inputs multimedia data such as video and audio.

  The A / D 102 digitally converts analog audio data input from the input unit 101.

The DSP 103 encodes the data digitized by the A / D 102 by a predetermined codec method, and frames the encoded data. Then, the DSP 103 generates a packet P ⁿ from one or a plurality of frame data. Packets P ⁿ generated by the DSP 103 are sequentially stored in a buffer unit 104A of the storage unit 104 described later.

The storage unit 104 includes an HD (Hard Disc Drive), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, and the like. As shown in FIG. 3, a buffer unit 104A and a duplicate packet buffer unit 104B, a storable number storage unit 104C, and a control table storage unit 104D. The storage unit 104 stores various programs such as an operation program, and stores various data such as the read timing (order) of the duplicate packet P ⁿ k determined by an order determination unit 105E of the control unit 105 described later. .

Buffer unit 104A sequentially stores packets ^{P n} generated by the DSP 103.

The duplicate packet buffer unit 104B stores the duplicate packet P ⁿ k generated from the packet P ⁿ by the duplicate packet generation unit 105D of the control unit 105 described later.

The storable number storage unit 104C stores a maximum storable number information table T1 illustrated in FIG. In this maximum storable number information table T1, as shown in FIG. 8, the receiving terminal device identification number ID for uniquely identifying the receiving terminal device 200 and the jitter buffer unit 202A of the receiving terminal device 200 can be stored. The maximum number M of RTP packets P ⁿ (or P ⁿ k) is stored in association with each other, and these pieces of information are stored by a maximum storable number calculation unit 106A described later. The receiving terminal device identification number ID may be anything as long as it can uniquely identify the receiving terminal device 200 of the communication partner, but in the present embodiment, the RR (Receiver Report) packet transmitted from the receiving terminal device 200 is included. An SSRC (Synchronization Source) identifier for identifying the creation source of the included RR packet is used.

The control table storage unit 104D stores a replication number control table T2 illustrated in FIG. As shown in FIG. 9, the copy number control table T2 associates the missing rate r with the copy number K of the copy packet P ⁿ k. The packet replication number determination unit 105C described later searches the missing rate r column of the replication number control table T2, and the RTP packet (UDP packet) acquired by the missing rate acquisition unit 105B from the RR packet transmitted by the receiving terminal device 200. by identifying the P ⁿ (or ^P n k) copy number K corresponding to the missing rate r of determining the copy number K of duplicate packets ^{P n} k to generate the packet ^{P n.}

The control unit 105 includes a CPU (Central Processing Unit) and the like, and controls each functional unit and executes an operation program stored in the storage unit 104, thereby allowing maximum storage as shown in FIG. The number calculation unit 105A, the missing rate acquisition unit 105B, the packet duplication number determination unit 105C, the duplicate packet generation unit 105D, the order determination unit 105E, the determination unit 105F, and the RTP processing unit 105G are realized. In addition, the control unit 105 executes various processes such as a read order determination process described later by executing the operation program. Further, the control unit 105 switches the read destination of the RTP processing unit 105G according to the timing (order) determined by the order determination unit 105E, and changes the duplicate packet P ⁿ k stored in the duplicate packet buffer unit 104B to RTP. The data is read by the processing unit 105G.

The maximum storable number calculation unit 105A calculates the maximum number M of RTP packets P ⁿ (or P ⁿ k) that can be stored in the jitter buffer unit 202A of the receiving terminal device 200 that is the communication partner, and calculates the maximum storable number M and the identification number ID that can uniquely identify the receiving terminal device 200 are associated with each other and stored in the maximum storable number information table T1.

Specifically, the maximum storable number calculation unit 105A is generated by the RTP processing unit 105G and responds to an SR (Sender Report) packet transmitted from the wireless communication unit 106 to the receiving terminal device 200, and receives the receiving terminal device 200. For example, the size of the jitter buffer unit 202A of the receiving terminal apparatus 200 is calculated (estimated) by using the following equation using the packet interval jitter (Interarrival Jitter) included in the RR packet transmitted from:
(Formula 1)
(Jitter buffer size) = (Packet interval jitter) × (RTP packet size) / (RTP packet transmission interval)

Then, the maximum storable number calculation unit 105A calculates the maximum number of RTP packets P ⁿ (or P ⁿ k) that can be stored in the jitter buffer unit 202A from the calculated size of the jitter buffer unit 202A of the receiving terminal device 200 according to the following equation. M is calculated. Here, rounddown is a natural number that is rounded down to the nearest decimal point. For example, in the case of rounddown (1.45), the value is “1”.
(Formula 2)
(Maximum storable number M) = rounddown {(jitter buffer size) / (RTP packet size)}

  The size information of the jitter buffer unit 202A of the receiving terminal device 200 can also be obtained by using an RTCP SDES (Source DEScription) packet. In this case, the RTP processing unit 105G, which will be described later, generates an SDES packet, transmits it to the receiving terminal device 200, acquires information on the size of the jitter buffer unit 202A from the response from the receiving terminal device 200, and calculates the maximum storable number The unit 106A calculates the maximum number M of RTP packets that can be stored in the jitter buffer unit 202A of the receiving terminal device 200 from the above-described Expression 2.

  Here, an RR (Receiver Report) packet transmitted from the receiving terminal device 200 in response to an SR (Sender Report) packet generated by the RTP processing unit 105G and transmitted from the wireless communication unit 106 to the receiving terminal device 200. explain. FIG. 10 is a diagram illustrating an example of the configuration of an RR packet. In the RR packet, an SSRC identifier that identifies a generation source of the RR packet, the above-described packet interval jitter, and the RTP packet ( Information such as the missing rate of UDP packets and the cumulative number of missing RTP packets (UDP packets) is included.

  Returning to FIG. 4, the missing rate acquisition unit 105 </ b> B is transmitted from the receiving terminal device 200 in response to an SR (Sender Report) packet generated by the RTP processing unit 105 </ b> G and transmitted from the wireless communication unit 106 to the receiving terminal device 200. RR packet is analyzed to obtain a missing rate r of RTP packets (UDP packets).

The packet replication number determination unit 105C searches the missing rate r column of the replication number control table T2 stored in the control table storage unit 104D, and corresponds to the missing rate r of the RTP packet acquired by the missing rate acquisition unit 105B. by specifying the number of copies K, determines the number K of the duplicate packet P ^{n k} be duplicated from the packet P ^n.

The duplicate packet generation unit 105D generates the number K of duplicate packets P determined by the packet duplication number determination unit 105C in the order from the packet ^Pn stored in the buffer unit 104A to the RTP processing unit 105G. ^{n k (k = 1, ...} , K) sequentially generates. The generated duplicate packet P ⁿ k is stored in the duplicate packet buffer unit 104B. For example, referring to the replication number control table T2 illustrated in FIG. 9, when the RTP packet loss rate r = 10%, the packet replication number determination unit 105C determines the number of replication packets P ⁿ k, K = 1. And decide. The duplicate packet generation unit 105D generates a duplicate packet ^{P n} 1 from the packet ^{P n.}

Order determining unit 105E is generated by duplicate packet generation unit 105D, a duplicate packet ^{P n} k stored in the buffer unit 104B for duplicate packets, and determines the timing (order) to read the RTP processing unit 105G, it was determined The read timing (order) of the duplicate packet P ⁿ k is stored in the storage unit 104. At this time, ^if the read timing of the duplicate packet P ⁿ k has already been stored, it is updated to the newly determined read timing (order). The control unit 105 switches the read destination of the RTP processing unit 105G according to the timing (order) determined by the order determination unit 105E, and transmits the duplicate packet P ⁿ k stored in the duplicate packet buffer unit 104B to the RTP processing unit. Read to 105G.

Specifically, the order determining unit 105E receives the copy packet P ⁿ k (k = 1,..., K) as the RTP processing unit after the copy source packet P ⁿ is read by the RTP processing unit 105G. It is determined whether the data is read by 105G. At this time, the order determination unit 105E refers to the maximum storable number information table T1 and counts from the copy source packet P ⁿ and reads it by the RTP processing unit 105G until the last copy packet P ⁿ K is read. The duplicate packet P ⁿ k is read so that the number MK of packets that have been received is equal to or less than the maximum storable number M of the jitter buffer unit 202A of the receiving terminal device 200 of the communication partner calculated by the maximum storable number calculation unit 105A. The timing (order) to be performed is determined. For example, by assigning different random numbers Lk (natural numbers satisfying 3 ≦ Lk ≦ M) to the duplicate packets P ⁿ k (k = 1,..., K), the above-described timing (order) can be determined. Become. A conventional method can be used to determine the random number Lk. Further, by setting the minimum value of Lk to 3, other packets always enter between the duplication source packet P ⁿ and the duplication packet P ⁿ k, and packet data having the same content is transmitted continuously. Absent. For this reason, the possibility of missing all packet data having the same content is reduced, and the reproduction quality of multimedia data is improved.

Here, a specific example will be described with reference to FIGS. In this example, the ID of the receiving terminal device 200 as the communication partner is ID1, the maximum storable number M1 = 7 in the jitter buffer unit 202A, and the loss rate r of the RTP packet transmitted to the receiving terminal device 200 having ID1 is Assume 21%. In this case, the duplicate packet generation unit 105D generates a duplicate packet ^{P n} 1 and ^{P n} 2 from the packet ^{P n,} and stores in the buffer unit 104B for duplicate packets. The order determining unit 105E determines the timing (order) at which the duplicate packets P ⁿ 1 and P ⁿ 2 are read so that the number of packets MK ≦ 7.

FIG. 11 is a diagram schematically showing the read timing (order) determined by the order determining unit 105E in this example. As shown in FIG. 11, the number of packets MK of the original packets P ⁿ , P ^{n + 1} , and P ^{n + 2} is equal to or less than the maximum storable number M1 = 7 in the jitter buffer unit 202A. The order determination unit 105E determines the timing (order) at which each of the duplicate packets P ⁿ k (k = 1,..., K) is read by the RTP processing unit 105G by the method described above. Then, the control unit 105 switches the reading destination of the RTP processing unit 105G according to the timing (order) determined by the order determining unit 105E, and transmits the duplicate packet P ⁿ k from the duplicate packet buffer unit 104B to the RTP processor 105G. Read. By doing so, it becomes possible to distribute the transmission timing of the RTP packet (UDP packet) P ⁿ (or P ⁿ k) transmitted to the receiving terminal device 200. As a result, even if a burst error occurs, the possibility that all the same RTP packets (UDP packets) P ⁿ and P ⁿ k are lost can be reduced, and the reproduction quality can be improved.

  Returning to FIG. 4, the determination unit 105 </ b> F determines whether or not the SR packet transmission timing has come, and periodically or intermittently generates the SR packet that is generated by the RTP processing unit 105 </ b> G and transmitted to the reception terminal device 200. In response, it is determined whether an RR packet transmitted from the receiving terminal device 200 of the communication partner has been received. Further, the determination unit 105F searches the receiving terminal device identification number ID field of the maximum storable number information table T1, and the SSRC identifier of the receiving terminal device 200 included in the RR packet transmitted from the receiving terminal device 200 is registered. It is determined whether or not.

The RTP processing unit 105G is generated by the DSP 103 under the control of the control unit 105, and is generated by the packet P ⁿ stored in the buffer unit 104A or the duplicate packet generation unit 105D and stored in the duplicate packet buffer unit 104B. The duplicate packets P ⁿ k are sequentially read out, RTP heads are added, and RTP packets P ⁿ (or P ⁿ k) are sequentially generated. The RTP header includes a time stamp indicating the transmission time of the RTP packet, a sequential number CN indicating the sequence number of the RTP packet transmission, and the like. Moreover, RTP processor 105G adds the UDP header to the generated RTP packet ^{P n} (or ^P n k), UDP packet ^{P n} (or ^P n k) generates, generated UDP packet ^P n ( Alternatively, P ⁿ k) is transmitted from the wireless communication unit 106 described later upon reception. The UDP header includes the IP address of the destination receiving terminal device 200 and the like.

  In addition, the RTP processing unit 105G generates an SR (Sender Report) packet periodically or intermittently and also generates an SDES (Source DEScription) packet or the like. The generated SR packet and the like are transmitted from the wireless communication unit 106 to the receiving terminal device 200 of the communication partner under the control of the control unit 105.

  The wireless communication unit 106 includes an antenna, a communication module, and the like, and transmits / receives data to / from the receiving terminal device 200.

  Next, the configuration of the reception terminal device 200 will be described with reference to FIGS. 5, 6, and 7. As shown in FIG. 5, the receiving terminal device 200 includes an output unit 201, a storage unit 202, a control unit 203, a wireless communication unit 204, and the like.

The output unit 201 includes a monitor such as an LCD (Liquid Crystal Display) and an organic EL (Electro-Luminescence), a speaker, and the like, and is generated from an RTP packet P ⁿ (or P ⁿ k) transmitted from the transmission terminal device 100. Video or audio data.

  The storage unit 202 includes HD, RAM, ROM, flash memory, and the like, and functions as a jitter buffer unit 202A as shown in FIG. The storage unit 202 stores various programs such as operation programs.

The jitter buffer unit 202A stores RTP packets P ⁿ (or P ⁿ k) sequentially transmitted from the transmission terminal apparatus 100 in the order of time stamps included in the RTP header.

The control unit 203 is composed of a CPU (Central Processing Unit) and the like, and controls each functional unit and executes an operation program stored in the storage unit 202, thereby, as shown in FIG. 203A and the function as the determination unit 203B are implemented, and various processes such as an RTP packet reception process described later are performed. In addition, when the determination unit 203B described later determines that the RTP packet P ⁿ (or P ⁿ k) including the same actual data has already been received, the control unit 203 receives the received RTP packet P ⁿ (or P ^{n n} k) is deleted, and when it is determined that the RTP packet P ⁿ (or P ⁿ k) including the same actual data has not been received yet, the received RTP packet P ⁿ (or P ⁿ k) is jittered. The data is stored in the buffer unit 202A.

  The RTP processing unit 203A generates an RR packet in response to the SR packet transmitted from the transmission terminal device 100, transmits the generated RR packet to the transmission terminal device 100 via the wireless communication unit 204, and transmits the RR packet. In response to the SDES packet transmitted from the terminal device 100, the size information of the jitter buffer unit 202A and the like are transmitted.

Judging unit 203B is configured to determine whether it has received the RTP packet ^{P n} (or ^P n k), the received RTP packets ^{P n} (or ^P n k) RTP containing the same actual data packet ^{P n} (or It is determined whether P ⁿ k) has already been received. That is, it is determined whether or not the RTP packet generated from the replication source packet P ⁿ or the replication packet P ⁿ k has already been received.

  The wireless communication unit 204 includes an antenna, a communication module, and the like, and transmits and receives data to and from the receiving terminal device 100.

  Next, with reference to FIG. 12, the flow of the reading order determination process of the transmission terminal device 100 will be described. This reading order determination process is triggered by the arrival of the SR packet transmission timing.

  The determination unit 105F determines whether it is the SR packet transmission timing (step S101). If it is determined that it is not the transmission timing of the SR packet (step S101; NO), the processing of step S101 is repeated to wait for the SR packet transmission timing.

  On the other hand, when it is determined that it is the transmission timing of the SR packet (step S101; YES), the RTP processing unit 105G generates an SR packet, and the control unit 105 controls the wireless communication unit 106 to generate the SR packet. The SR packet is transmitted to the receiving terminal device 200 (step S102).

  And the determination part 105F determines whether the RR packet transmitted from the receiving terminal device 200 of a communication other party was received in response to the SR packet transmitted by the process of step S102 (step S103). If it is determined that the RR packet has not been received (step S103; NO), the process of step S103 is repeated to wait for the RR packet to be received.

  On the other hand, when it is determined that the RR packet has been received (step S103; YES), the determination unit 105F further receives the maximum storable number information table T1 stored in the storable number storage unit 104C. By searching the identification number ID column and determining whether the SSRC identifier included in the received RR packet is registered, the maximum storable number M of the jitter buffer unit 202A of the receiving terminal device 200 of the communication partner can be stored at the maximum. It is determined whether it is stored in the number information table T1 (step S104).

  If it is determined that the maximum storable number M of the jitter buffer unit 202A of the receiving terminal device 200 of the communication partner is stored in the maximum storable number information table T1 (step S104; YES), the process proceeds to step S106. Proceed to processing.

On the other hand, if it is determined that the maximum storable number M of the jitter buffer unit 202A of the receiving terminal device 200 of the communication partner is not stored in the maximum storable number information table T1 (step S104; NO), the maximum storable number The number calculation unit 105A calculates the maximum number M of RTP packets P ⁿ (or P ⁿ k) that can be stored in the jitter buffer unit 202A of the receiving terminal device 200 that is the communication partner, and receives the calculated maximum storable number M and reception The terminal device 200 is associated with an identification number ID (SSRC identifier included in the RR packet) that can uniquely identify the terminal device 200 and stored in the maximum storable number information table T1 (step S105).

  Then, the missing rate acquisition unit 105B analyzes the received RR packet and acquires the missing rate r of the RTP packet (UDP packet) included in the RR packet (step S106).

Then, the packet replication number determination unit 105C searches the missing rate r column of the replication number control table T2 stored in the control table storage unit 104D, and sets the RTP packet missing rate r acquired by the missing rate acquisition unit 105B. by identifying the corresponding copy number K, it determines the number K of the duplicate packet ^{P n} k be duplicated from the packet ^{P n} (step S107).

Then, the duplicate packet generation unit 105D performs the number K of duplications determined by the packet duplication number determination unit 105C in the order from which the packet ^Pn stored in the buffer unit 104A is read out to the RTP processing unit 105G. Packets P ⁿ k (k = 1,..., K) are sequentially generated. Then, the duplicate packet generation unit 105D sequentially stores the duplicate packet P ⁿ k thus generated in the duplicate packet buffer unit 104B (step S108).

Then, the order determination unit 105E determines the timing (order) at which the RTP processing unit 105G reads the duplicate packet P ⁿ k generated by the duplicate packet generation unit 105D and stored in the duplicate packet buffer unit 104B. stores the determined duplicated packet ^{P n} k of the read timing (order) in the storage unit 104 (step S109). At this time, ^if the read timing (order) of the duplicate packet P ⁿ k is already stored in the storage unit 104, it is updated to the newly determined read timing (order).

The control unit 105 transfers the read destination by the RTP processing unit 105G from the buffer unit 104A to the copy packet buffer unit 104B according to the read timing (order) of the copy packet determined by the order determination unit 105E stored in the storage unit 104. Switch. RTP processor 105G according to the control of the control unit 105, from the buffer unit 104A or the duplicate packet buffer unit 104B, sequentially reads the packet ^{P n} or the duplicate packet ^{P n} k, from the read packet ^{P n} or the duplicate packet ^{P n} k RTP (UDP) packets are sequentially generated (step S110). In this case, if the storage unit 104 read timing (order) is not stored, the buffer unit 104B for duplicate packet, since the duplicate packet P ^{n k} is not stored, the control unit 105, buffer unit 104A And switching between the duplicate packet buffer unit 104B are not performed.

Then, sequentially generated RTP (UDP) packets P ⁿ or P ⁿ k under the control of the control unit 105 are sequentially transmitted to the receiving terminal device 200 of the communication partner via the wireless communication unit 106 (step S111). .

  Next, a flow of RTP (UDP) packet reception processing of the reception terminal device 200 will be described with reference to FIG.

The determination unit 203B determines whether or not an RTP (UDP) packet P ⁿ or P ⁿ k has been received (step S201). If it is determined that the RTP (UDP) packet P ⁿ or P ⁿ k has not been received (step S201; NO), the processing of step S201 is repeated, and the RTP (UDP) packet P ⁿ or P ⁿ k is received. Wait for it.

On the other hand, when it is determined that the RTP (UDP) packet P ⁿ or P ⁿ k has been received (step S201; YES), the determination unit 203B further receives the received RTP packet P ⁿ (or P ⁿ k). It is determined whether or not an RTP packet P ⁿ (or P ⁿ k) including the same actual data has already been received (step S202).

When it is determined that the RTP packet P ⁿ (or P ⁿ k) including the same actual data has already been received (step S202; YES), the control unit 203 receives the received RTP packet P ⁿ (or P ⁿ k) is deleted (step S203), and when it is determined that the RTP packet P ⁿ (or P ⁿ k) including the same actual data has not yet been received (step S202; NO), the control unit 203 The received RTP packet P ⁿ (or P ⁿ k) is stored in the jitter buffer unit 202A in the order according to the generation number of the multimedia data or the sequential number CN indicating the transmission order of the RTP packet (step S204). These series of processes are repeated until all RTP packets P ⁿ (or P ⁿ k) are received.

  Next, the flow of the RR packet transmission process of the receiving terminal device 200 will be described with reference to FIG.

  The determination unit 203B determines whether or not an SR packet transmitted from the transmission terminal device 100 has been received (step S301). If it is determined that the SR packet has not been received (step S301; NO), the process of step S301 is repeated to wait for the SR packet to be received.

  On the other hand, when it is determined that the SR packet has been received (step S301; YES), the RTP processing unit 203A generates an RR packet in response to the SR packet, and the wireless communication unit is controlled by the control unit 203. The generated RR packet is transmitted to the transmission terminal apparatus 100 via 204 (step S302), the process returns to the process of step S301, and the above-described process is repeated.

Here, referring to FIG. 15, based on a specific example, it is read according to the read timing (order) of the duplicate packet P ⁿ k determined by the read order determination process described above, and is encapsulated by the RTP processing unit 105G. Next, how the RTP (UDP) packet P ⁿ (or P ⁿ k) sequentially transmitted after that is received in the receiving terminal device 200 will be described.

FIG. 15A is a diagram schematically showing the order of the packet P ⁿ or the duplicate packet P ⁿ k read from the buffer part 104A or the duplicate packet buffer part 104B by the RTP processor 105G. FIG. 15B shows an RTP (UDP) packet that is read from the buffer unit 104A or the duplicate packet buffer unit 104B, encapsulated by the RTP processing unit 105G, and sequentially sent to the IP network via the wireless communication unit 106. some of the P n ^(or P ^{n k)} is a diagram schematically showing that it is lost in the propagation process. FIG. 15C is a diagram schematically illustrating a state in which the RTP packet P ⁿ (or P ⁿ k) received by the receiving terminal device 200 is stored in the jitter buffer.

As shown in FIG. 15B, RTP (UDP) packet P ¹ , RTP (UDP) packet P ¹ 1, RTP (UDP) packet P ² 2, RTP (UDP) packet P ³ , RTP ( UDP) packet P ⁴ 1, RTP (UDP) packet P ⁴ 2, RTP (UDP) packet P ⁶ and RTP (UDP) packet P ⁵ 2 are lost in the propagation process. That is, the RTP (UDP) packet received by the receiving terminal device 200 includes the packet P ² , the packet P ² 1, the packet P ¹ 2, the packet P ³ 1, the packet P ^4, and the packet P ³ 2. , Packet P ⁵ , packet P ⁵ 1, and packet P ⁶ 1. Although the order of reception may be changed due to so-called fluctuations that occur in the propagation process, in this example, description will be made assuming that the signals are received in the above order, that is, in the order of transmission.

Upon receiving the packet ^{P 2} (step S201; YES), before the packet ^{P 2,} the packet including the same real data, that is not received duplicate packets ^{P 2} 1 and ^{P 2} 2 (step S202; NO) , the control unit 203 stores the packet ^{P 2} in the jitter buffer section 202A (step S204). Next, when the packet P ² 1 is received (step S201; YES), since the packet P ² has already been received and stored in the jitter buffer unit 202A (step S202; YES), the control unit 203 receives the packet P ² 1. Delete (step S203).

Next, when receiving the packet ^{P 1} 2 (step S201; YES), the packet ^{P 1} before the packet ^{P 1} 2, because no packet is received ^{P 1} 2 (step S202; NO), the control unit 203, a packet P ¹² is stored in the jitter buffer unit 202A (step S204). Next, when the packet P ³ 1 is received (step S201; YES), the packet P ³ and the packet P ³ 2 are not received before the packet P ³ 1 (step S202; NO). P ³¹ is stored in the jitter buffer unit 202A (step S204).

Next, when receiving the packet ^{P 4} (step S201; YES), the packet ^P 4 1 before the packet ^{P 4,} because no packet is received ^{P 4} 2 (step S202; NO), the control unit 203, packet P ⁴ is stored in the jitter buffer unit 202A (step S204). Next, when the packet P ³ 2 is received (step S201; YES), the packet P ³ 1 has already been received before the packet P ³ 2 and stored in the jitter buffer unit 202A (step S202; NO). Unit 203 deletes packet P ³ 2.

Next, when receiving the packet ^{P 5} (step S201; YES), the packet ^P 5 1 before the packet ^{P 5,} since no packet is received ^{P 5} 2 (step S202; NO), the control unit 203, packet P ⁵ is stored in the jitter buffer unit 202A (step S204). Next, when receiving the packet ^{P 5} 1 (step S201; YES), already received the packet ^{P 5} before the packet ^{P 5} 1, since they are stored in the jitter buffer section 202A (step S202; NO), the control unit 203 deletes the packet P ⁵ 1.

Next, when the packet packet P ⁶ 1 is received (step S201; YES), the packet P ⁶ and the packet P ⁶ 2 are not received before the packet P ⁶ 1 (step S202; NO). stores the packet ^{P 6} 1 to the jitter buffer section 202A (step S204).

According to the first embodiment, the number of duplicate packets P ⁿ k to be generated is determined according to the loss rate of the transmitted RTP (UDP) packet P ⁿ (or P ⁿ k), and the read timing of the duplicate packet P ⁿ k is determined. (Order) was determined. Thereby, the RTP packet P ⁿ generated from the copy source packet P ^n, it is possible to open the transmission interval of the RTP packet P ^{n k} generated from the duplicate packet P ^{n k,} occurs a burst error In addition, it is possible to reduce the possibility that all RTP packets P ⁿ and P ⁿ k (k = 1,..., K) including the same actual data are lost.

Further, according to the first embodiment, counting from the copy source packet P ⁿ of read timing (order N), the timing of the last duplicate packet P ^{n k} is read (the order Nk) is a communication partner receiving terminal The read timing (order) is determined so as not to exceed the maximum storable number M of RTP packets P ⁿ (or P ⁿ k) in the jitter buffer unit 202A of the apparatus 200, that is, Nk−N + 1 ≦ M. . Thereby, for example, even RTP generated from the copy source packet ^{P n} (UDP) packet ^{P n} is lost in the propagation process, RTP generated from the duplicate packet ^{P n} k (UDP) packets ^P n k If the receiving terminal device 200 can receive any of the above, it is possible to absorb the reception delay caused by the loss in the jitter buffer unit 202A, so that it is possible to improve the reproduction quality of moving images or sounds.

(Embodiment 2)
In the first embodiment, for example, by assigning different random numbers Lk (natural numbers satisfying 3 ≦ Lk ≦ maximum storable number M) to the respective duplicate packets P ⁿ k (k = 1,..., K), duplicate packets It has been described that the timing (order) at which the RTP processing unit 005G reads the duplicate packet P ⁿ k stored in the buffer unit 104B is determined.

In this embodiment, the timing (order) at which the duplicate packet P ⁿ k is read by the RTP processing unit 105G is determined using the order specifying table T3 illustrated in FIG.

  The configuration of the transmission terminal device 100 and the reception terminal device 200 in the present embodiment is basically the same as the configuration in the first embodiment. However, as shown in FIG. 16, the point that the storage unit 104 of the transmission terminal device 100 further functions as the order specification table storage unit 104E is different from that of the first embodiment. Further, the functions of the order determination unit 105E are slightly different from those of the first embodiment.

The storage unit 104 further functions as the order specification table storage unit 104E. The order specification table storage unit 104E stores in advance an order specification table T3 illustrated in FIG. The order identification table T3, the copy number K of duplicate packets P ^{n k,} and the maximum storable number M of the jitter buffer section 202A, duplicate packets P specified by the relationship between the copy number K and the maximum storable number M ^{n k} readout timing as (order), is associated.

The order determination unit 105E refers to the order specification table T3 stored in advance in the order specification table storage unit 104E, and stores the maximum number of copies K of the duplicate packet P ⁿ k determined by the packet copy number determination unit 105C. From the maximum storable number M of the jitter buffer unit 202A of the receiving terminal device 200 of the communication partner calculated by the possible number calculation unit 105A, the read timing (order) of the duplicate packet P ⁿ k is specified. Then, the order determining unit 105E stores the specified read timing (order) in the storage unit 104. At this time, if the read timing (order) is already stored in the storage unit 104, the update is performed at the specified read timing (order).

Referring to FIG. 17, for example, the number of duplicates of duplicate packet P ⁿ k is determined by packet duplication number determining section 105C to be K = 2, and the maximum storable number calculating section 105A is a jitter buffer section of receiving terminal apparatus 200 of the communication partner. When it is calculated that the maximum storable number M = 5 of 202A, the order determination unit 105E refers to the order specification table T3 as the read timing (order) of the duplicate packets P ⁿ 1 and P ⁿ 2 (3). , 5). In (3, 5), the duplicate packet P ⁿ 1 is counted from the duplicate packet, and is read out by the RTP processing unit 105G at the third timing (order). The duplicate packet P ⁿ 2 is This means that the RTP processing unit 105G reads the data from the packet at the fifth timing (order).

Further, for example, the number of duplicates of the duplicate packet P ⁿ k is determined by the packet duplication number determination unit 105C to be 3 and the maximum storable number calculation unit 105A can store the maximum in the jitter buffer unit 202A of the receiving terminal device 200 of the communication partner. When the number M = 8 is calculated, the order determination unit 105E refers to the order specification table T3 as the read timing (order) of the duplicate packets P ⁿ 1, P ⁿ 2, and P ⁿ 3 (3, 3). 5, 8) is specified.

Under the control of the control unit 105, the RTP processing unit 105G counts from the read timing (order) of the replication source packet ^Pn and stores it in the duplicate packet buffer unit 104B at the third read timing (order). The duplicate packet P ⁿ 1 is read, the duplicate packet P ⁿ 2 is read at the fifth read timing (order), and the duplicate packet P ⁿ 3 is read at the eighth read timing (order).

According to the second embodiment, the order determining unit 105E refers to the order specifying table T3 stored in advance in the order specifying table storage unit 104E, and determines the duplicate packet P ⁿ k determined by the packet replication number determining unit 105C. a copy number K of the maximum number of storable M jitter buffer portion 202A of the receiving terminal device 200 of the communication partner that has been calculated by the maximum storable number calculating section 105A from, duplicate packets P ^{n k} of the read timing (order) Identified. This makes it possible to reliably distribute the read timing (order) of the copy source packet P ⁿ and each copy packet P ⁿ k (k = 1,..., K). Therefore, all of the RTP (UDP) packets P ⁿ and P ⁿ k generated from the original packet P ⁿ and the duplicate packet P ⁿ k (k = 1,..., K) including the same actual data are caused by the burst error. The possibility of being lost can be further reduced.

(Embodiment 3)
In the first and second embodiments, every time the RR packet transmitted from the receiving terminal device 200 is received, the process of determining the read timing (order) of the duplicate packet P ⁿ k is executed. In the present embodiment, when the missing rate included in the RR packet has not changed from the previous time, or when the copy number K determined by the packet copy number determination unit 105C has not changed from the previous time, the duplicate packet The processing speed can be increased by using the previously determined timing (order) without executing the determination process of the reading timing (order) of P ⁿ k.

  The configurations of the transmission terminal device 100 and the reception terminal device 200 in the present embodiment are basically the same as those in the first embodiment. However, as shown in FIG. 18, the configuration of the functional unit of the control unit 105 realized by the CPU executing the operation program is different, and a missing rate storage unit 105H and a packet duplication number storage unit 105I are further added. The function performed by the determination unit 105F is slightly different from that in the first embodiment.

The determination unit 105F further compares the missing rate r of the RTP (UDP) packet P ⁿ (or P ⁿ k) acquired by the missing rate acquisition unit 105B with the missing rate stored in the storage unit 104, Determine if it has changed. At this time, if the missing rate is not stored in the storage unit 104, the determination unit 105F determines that it has changed. Further, the determination unit 105F determines whether or not the replication number K determined by the packet replication number determination unit 105C has changed compared to the replication number stored in the storage unit 104. At this time, if the replication number K determined by the packet replication number determination unit 105C is not stored in the storage unit 104, the determination unit 105F determines that it has changed.

  When the determination unit 105F determines that the missing rate r acquired by the missing rate acquisition unit 105B has changed compared to the missing rate stored in the storage unit 104, the missing rate storage unit 105H The missing rate r acquired by the missing rate acquisition unit 105B is stored in the storage unit 104, and the missing rate r stored in the storage unit 104 is updated.

The packet replication number storage unit 105I changes the generation number K of the duplicate packet P ⁿ k determined by the packet replication number determination unit 105C by the determination unit 105F in comparison with the replication number stored in the storage unit 104. If it is determined that the number of copies, the copy number K of the duplicate packet P ⁿ k determined by the packet copy number determination unit 105C is stored in the storage unit 104, and the copy number K stored in the storage unit 104 is updated. .

  Next, with reference to FIG. 19, the flow of the reading order determination process in the present embodiment will be described. In addition, the same code | symbol is attached | subjected about the process (step) same as Embodiment 1. FIG. That is, Step S401, Step S402, S403, and Step S404 are added after the missing rate acquisition step of Step S106 and after the packet replication number determination step of Step S107, respectively.

  Since the processing from step S101 to step S106 and the processing from step 108 to step 111 are the same as in the first embodiment, the processing from step S106 will be described here.

The missing rate acquisition unit 105B analyzes the received RR packet and acquires the missing rate r (step S106). The determination unit 105F determines whether the missing rate r acquired by the missing rate acquisition unit 105B has changed compared to the missing rate stored in the storage unit 104 (step S401). When it is determined that the missing rate r acquired by the missing rate acquisition unit 105B in the process of step S106 has not changed (step S401; NO), the duplicate packet generation unit 105D is stored in the storage unit 104. Based on the number K of duplicates, a duplicate packet P ⁿ k is generated (step S405).

Then, the process proceeds to processing in step S110, the control unit 105 according to the read timing stored in the storage unit 104 (the order), to read the duplicate packet ^{P n} k the RTP processing unit 105G, RTP processor 105G Sequentially generates RTP (UDP) packets P ⁿ (or P ⁿ k) from the read packets P ⁿ or duplicate packets P ⁿ k (step S110).

On the other hand, when it is determined that the missing rate r acquired this time has changed (step S401; YES), the missing rate storage unit 105H stores the missing rate r acquired by the missing rate acquisition unit 105B in the storage unit 104. Then, the missing rate r stored in the storage unit 104 is updated (step S402). Then, the packet replication number determination unit 105C searches the missing rate r column of the replication number control table T2 stored in the control table storage unit 104D, and sets the RTP packet missing rate r acquired by the missing rate acquisition unit 105B. by identifying the corresponding copy number K, it determines the number K of the duplicate packet ^{P n} k be duplicated from the packet ^{P n} (step S107).

Then, the determination unit 105F determines whether or not the copy number K of the copy packet P ⁿ k determined by the packet copy number determination unit 105C has changed compared to the copy number stored in the storage unit 104. (Step S403). When it is determined that the replication number K determined by the packet replication number determination unit 105C has not changed (step S403; NO), the replication packet generation unit 105D determines the replication number K stored in the storage unit 104. Based on, a duplicate packet P ⁿ k is generated (step S405).

Then, the process proceeds to processing in step S110, the control unit 105 according to the read timing stored in the storage unit 104 (the order), to read the duplicate packet ^{P n} k the RTP processing unit 105G, RTP processor 105G Sequentially generates RTP (UDP) packets P ⁿ (or P ⁿ k) from the read packets P ⁿ or duplicate packets P ⁿ k (step S110).

  On the other hand, when it is determined that the replication number K determined by the packet replication number determination unit 105C has changed (step S403; YES), the packet replication number storage unit 105I is determined by the packet replication number determination unit 105C. The number of copies K is stored in the storage unit 104, and the number of copies stored in the storage unit 104 is updated (step S404).

According to the third embodiment, only when the drop rate r changes and the replication number K determined by the packet replication number determination unit 105C changes, the order determination unit 105E reads the replication packet P ⁿ k. (Order) was determined. By doing so, it is possible to realize high-speed processing.

(Modification 1)
It has been described that in the reading order determination process in the embodiment, the process waits for the reception of the RR packet (step S103) and proceeds to the processes after step S104. However, the present invention is not limited to this. For example, the control unit 105 may include an internal timer, and the flow of the reading order determination process may be configured as shown in FIG.

  The SR packet generated by the RTP processing unit 105G is transmitted (step S102), and an internal timer is started (step S601). And the determination part 105F determines whether the RR packet transmitted from the receiving terminal device 200 of a communication other party was received in response to the SR packet transmitted by the process of step S102 (step S103). If it is determined that the RR packet has been received (step S103; YES), the process proceeds to the process of step S104.

  On the other hand, when it is determined that the RR packet has not been received (step S103; NO), the determination unit 105F determines whether or not the internal timer has timed out (step S602). If it is determined that the time-out has not occurred (step S602; NO), the process returns to the process of step S103 and repeats the above-described process.

  On the other hand, when it is determined that a time-out has occurred (step S602; YES), the determination unit 105F displays the receiving terminal device identification number ID column of the maximum storable number information table T1 stored in the storable number storage unit 104C. A search is performed to determine whether or not the maximum storable number M of the jitter buffer unit 202A of the receiving terminal device 200 of the communication partner is stored in the maximum storable number information table T1 (step S603).

If it is determined that the maximum storable number M of the jitter buffer unit 202A of the receiving terminal device 200 that is the communication partner has already been stored in the maximum storable number information table T1 (step S603; YES), the duplicate packet The generation unit 105D generates a duplicate packet P ⁿ k based on the number of duplicates K stored in the storage unit 104 (Step S604).

Then, the process proceeds to processing in step S110, the control unit 105 according to the read timing stored in the storage unit 104 (the order), to read the duplicate packet ^{P n} k the RTP processing unit 105G, RTP processor 105G Sequentially generates RTP (UDP) packets P ⁿ (or P ⁿ k) from the read packets P ⁿ or duplicate packets P ⁿ k (step S110).

On the other hand, when it is determined that the maximum storable number M of the jitter buffer unit 202A of the receiving terminal device 200 that is the communication partner is not stored in the maximum storable number information table T1 (step S603; NO), packet duplication The number determination unit 105C determines that the number of copies K = 1 of the duplicate packet P ⁿ k (step S605). And a process progresses to the process of step S108 or step S403.

According to the first modification example, when the RR packet transmitted from the receiving terminal device 200 that is the transmission destination of the SR packet cannot be received within the predetermined time (step S602; YES), the maximum storable number information table T1 is stored. It is determined whether the maximum storable number M of the receiving terminal device 200 that is the communication partner is stored (step S603). If not stored (step S603; NO), the packet replication number determination unit 105C It is determined that the number of copies K = 1 of the packet P ⁿ k is 1 (step S605). On the other hand, if it is stored (step S603; YES), the duplicate packet generator 105D determines the duplicate packet P ⁿ k based on the duplicate number K of duplicate packets P ⁿ k stored in the storage unit 104. generated (step S604), and to read the duplicate packet ^{P n} k using the read timing stored in the storage unit 104. In this way, even when the RR packet is lost for any reason, it is possible to appropriately execute the reading order determination process.

(Modification 2)
Further, the RR packet transmitted from the receiving terminal device 200 that is the transmission destination of the SR packet cannot be received within a predetermined time (step S602; YES), and the maximum storable number M of the receiving terminal device 200 that is the communication partner is received. Is not stored in the maximum storable number information table T1 (step S603; NO), as shown in FIG. 21, the missing rate r of the RTP (UDP) packet is estimated from the reception rate of the RR packet. Good (step S701).

  In the above embodiment, the division of the missing rate in the copy number control table T2 is an example, and the division may be subdivided, or conversely, the number of divisions may be reduced.

  Further, in the above embodiment, the size of the jitter buffer unit 202A of the receiving terminal device 200 that is the communication partner is obtained by obtaining the round trip time RTT from the reception time of the RR packet and the LSR and DLSR included in the RR packet. It is also possible to estimate.

Further, in the above embodiment, a duplicate of the packet P ⁿ generated by the DSP 103 is generated, the generated duplicate packet P ⁿ k is stored in the duplicate packet buffer unit 104B, and the read timing determined by the order determining unit 105E ( In accordance with the order), the RTP processing unit 105G is caused to read the duplicate packet P ⁿ k. However, the present invention is not limited to this. For example, instead of generating a copy of the packet P ⁿ generated by the DSP 103, a copy of the RTP (UDP) packet P ⁿ generated by the RTP processing unit 105G is generated. May be. In this case, the generated duplicate RTP (UDP) packet P ⁿ k may be configured to be transmitted to the receiving terminal apparatus 200 according to the transmission timing determined by the order determining unit 105E.

In the above embodiment 1, for example, duplicate packets ^{P n k (k = 1,} ..., K) for each, (a natural number satisfying 3 ≦ Lk ≦ maximum number of storable M) different random Lk By assigning Although it has been described that the timing (order) at which the RTP processing unit 005G reads the duplicate packet P ⁿ k stored in the duplicate packet buffer unit 104B is determined, the duplicate packet P ⁿ k (k = 1,..., K ) A different random number Lk (2 ≦ Lk ≦ natural number satisfying the maximum storable number M) may be assigned to each. In this case, for example, whether the random numbers Lk assigned to the duplicate packets P ⁿ k (k = 1,..., K) are not consecutive numbers from 2, that is, all the assigned random numbers Lk are K + 1. It may be determined whether or not it is less than or equal, and if all the random numbers Lk are equal to or less than K + 1, the random number Lk may be assigned again. By doing so, other packets always enter between the duplication source packet P ⁿ and the duplication packet P ⁿ k, and packet data having the same contents are not transmitted continuously. For this reason, the possibility of missing all packet data having the same content is reduced, and the reproduction quality of multimedia data is improved.

Moreover, in the said Embodiment 2, each timing (order) of the order specific table T3 is an example, and is not limited to this, Read timing (order) of the replication source packet P ⁿ and the replication packet P ⁿ k The timing (order) can be set arbitrarily.

In the above embodiment, the program to be executed is a computer-readable recording medium such as a flexible disk, a CD-ROM (Compact Disc Read-Only Memory), a DVD (Digital Versatile Disc), and an MO (Magneto-Optical Disc). The above-described processing may be executed by storing and distributing the program and installing the program.
Further, the program may be stored in a disk device or the like included in a predetermined server device on a communication network such as the Internet, and may be acquired by being superimposed on a carrier wave, for example.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the specific embodiment which concerns, This invention includes the invention described in the claim, and its equivalent range It is.

1 Data Transmission / Reception System NW IP Network 001 Input Unit 002 A / D
003 DSP
004 Output unit 005 Storage unit 006 Control unit 007 Operation unit 008 Wireless communication unit 100 Transmission terminal device 101 Input unit 102 A / D
103 DSP
104 storage unit 104A buffer unit 104B duplicate packet buffer unit 104C storable number storage unit 104D control table storage unit 104E order specification table storage unit 105 control unit 105A maximum storable number calculation unit 105B missing rate acquisition unit 105C packet replication number determination unit 105D Duplicate packet generation unit 105E Order determination unit 105F Judgment unit 105G RTP processing unit 105H Missing rate storage unit 105I Packet replication number storage unit 106 Wireless communication unit 200 Receiving terminal device 201 Output unit 202 Storage unit 202A Jitter buffer unit 203 Control unit 203A RTP Processing unit 203B Determination unit 204 Wireless communication unit T1 Maximum storable number information table T2 Replication number control table T3 Order identification table RR RR packet B bus

Claims (13)

A communication unit that transmits a packet including multimedia data to a receiving terminal device via a network;
A duplicate packet generator for generating a duplicate of the packet;
At least one other packet is inserted between the transmission order of the replication source packet and the transmission order of the replicated packet, and the replicated packet and the replication source packet are transmitted to the receiving terminal device. An order determination unit for determining the order;
In accordance with the order determined by the order determination unit, a control unit for controlling the timing of transmitting the duplicated packet and the original packet,
A transmission terminal device comprising: A communication with the receiving terminal device further comprises a missing rate acquisition unit for acquiring a missing rate that is a ratio of lost packets transmitted in the propagation process to the receiving terminal device,
The duplicate packet generation unit generates a number of copies of the packet according to the packet loss rate acquired by the loss rate acquisition unit;
The transmission terminal apparatus according to claim 1. The missing rate acquisition unit intermittently acquires the missing rate of the packet,
The order determination unit determines the order of transmitting the duplicated packet and the duplication source packet to the receiving terminal device each time the missing rate acquisition unit obtains the missing rate of the packet.
The transmission terminal apparatus according to claim 2, wherein: A determination unit that determines whether the missing rate acquired this time by the missing rate acquisition unit has changed from the previously acquired missing rate;
Only when it is determined that there is a change in the missing rate, the order determination unit determines the order in which the duplicated packet and the duplicated source packet are transmitted to the receiving terminal device.
The transmission terminal device according to claim 3. A control table storage unit that stores in advance a replication number control table in which the packet loss rate and the packet replication number are associated with each other;
With reference to the replication number control table, a packet replication number determination unit that determines the replication number of the packet from the deletion rate acquired by the deletion rate acquisition unit;
Further comprising
The duplicate packet generator generates duplicate packets for the number of replicas determined by the packet replica number determiner;
The transmission terminal device according to claim 2, wherein the transmission terminal device is a transmission terminal device. A maximum storable number calculating unit that calculates the maximum number of packets that can be stored in a jitter buffer included in the receiving terminal device by communication with the receiving terminal device;
The order determination unit determines whether a difference between an order in which the last transmitted packet is transmitted and an order in which the first transmitted packet is transmitted among the copied packet and the original packet. Determining the transmission timing so as to be smaller than the maximum number calculated by the maximum storable number calculation unit;
The transmission terminal apparatus according to claim 1, wherein the transmission terminal apparatus is a transmission terminal apparatus. The order determining unit randomly determines the order of transmitting the duplicated packet and the duplication source packet to the receiving terminal device.
The transmission terminal device according to claim 1, wherein the transmission terminal device is a transmission terminal device. A maximum storable number calculating unit that calculates the maximum number of packets that can be stored in a jitter buffer included in the receiving terminal device by communication with the receiving terminal device;
In order to specify the order of transmitting the duplicated packet and the duplication source packet to the receiving terminal device from the packet drop rate and the maximum number of packets that can be stored in the jitter buffer of the receiving terminal device An order specification table storage unit for storing the order specification table in advance,
Further comprising
The order determining unit refers to the order specifying table and replicates the packet from the packet loss rate acquired by the loss rate acquisition unit and the maximum number calculated by the maximum storable number calculation unit. Determining the order in which the received packet and the duplication source packet are transmitted to the receiving terminal device,
The transmission terminal device according to claim 2, wherein the transmission terminal device is a transmission terminal device. The transmission of multimedia data to the receiving terminal device is real-time,
The transmission terminal apparatus according to claim 1, wherein the transmission terminal apparatus is a transmission terminal apparatus. The network is a wireless network;
The transmission terminal device according to claim 1, wherein the transmission terminal device is a transmission terminal device. A data transmission / reception system comprising: a transmission terminal device that transmits multimedia data via a network; and a reception terminal device that receives multimedia data transmitted from the transmission terminal device,
The transmitting terminal device
A communication unit that transmits a packet including the multimedia data to the receiving terminal device via the network;
A duplicate packet generator for generating a duplicate of the packet;
At least one other packet is inserted between the transmission order of the duplicate packet and the transmission order of the duplicate packet, and the duplicate packet and the duplicate packet are transmitted to the receiving terminal device. An order determination unit for determining the order;
In accordance with the order determined by the order determination unit, the control unit for controlling the timing of transmitting the replicated packet and its replication source packet;
With
The receiving terminal device
A communication unit that receives the packet transmitted from the transmission terminal device;
A determination to determine whether a packet including multimedia data identical to the multimedia data included in the received packet is received before receiving the received packet each time the packet is received And
When it is determined by the determination unit that a packet including the same multimedia data has already been received, a control unit that deletes the received packet;
Comprising
A data transmission / reception system characterized by the above. The sending terminal device
Generate duplicates of packets containing multimedia data,
Order in which at least one other packet is inserted between the transmission order of the duplication source packet and the duplication packet transmission order, and the duplication packet and the duplication source packet are transmitted to the receiving terminal device Decide
In accordance with the determined order, the duplicated packet and the duplication source packet are transmitted to the receiving terminal device.
A data transmission method characterized by the above. To a computer having a function of transmitting multimedia data to a receiving terminal device of a communication partner via a network,
Generating a copy of the packet containing the multimedia data;
At least one other packet is inserted between the transmission order of the replication source packet and the transmission order of the replicated packet, and the replicated packet and the replication source packet are transmitted to the receiving terminal device. Processing to determine the order;
In accordance with the determined order, a process of transmitting the duplicated packet and its original packet to the receiving terminal device;
A program characterized by having executed.

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