JP2002314583A - Relay method and gateway - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gateway and a relay method where a reception terminal makes no re-transmission request with respect to a packet loss for a wired block. SOLUTION: The gateway analyzes a header of a received packet to check whether or not a packet with high importance for the wired block has a loss, and when a packet loss takes place, the gateway corrects the header of the packet so as to prevent a reception terminal from detecting the packet loss and from making a re-transmission request.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relay method, a relay device, and a receiving terminal, and more particularly, to a relay method, a relay device, and a relay device for receiving a packet transmitted from a transmitting terminal and transmitting the packet to a receiving terminal. The present invention relates to a receiving terminal that decodes data included in a received packet.

[0002]

2. Description of the Related Art Real-time video content viewing and listening services require RTP (Real-time Transport).
Protocol) / UDP (User Datagram Protocol) / IP (Int
ernetProtocol) is considered suitable and 3GPP
(Third Generation Partnership Project = an organization that defines international standards for 3G mobile communications)
It is expected that UDP / IP will be adopted. RTP / UDP /
IP does not have a mechanism for retransmitting a packet when a packet loss occurs, so data cannot be reliably delivered to the terminal. However, since retransmission does not occur, data can be transmitted without losing real-time performance. There is.

As data to be transmitted, for example, there is image data compressed and encoded by the moving picture compression technology MPEG4. In the case of moving image contents, since the image data cannot be decoded in a portion where packet loss has occurred, the portion is generally interpolated in the immediately preceding frame. MP
In the EG4, similarly to the MPEG1 and the MPEG2, there are a frame (intra frame) that can be decoded only by the image frame and a frame (inter frame) that is decoded by using difference information between frames before and after the frame. Generally, one intra frame is arranged every 1 to 5 seconds, and the other is arranged with an inter frame. Therefore, if a packet including an intra frame is lost due to a transmission error, the effect is propagated to a subsequent inter frame, so that the effect on the image quality is large.

[0004] Therefore, a packet containing important data such as an intra frame should be retransmitted.
The Internet Engineering Task Force (ETF) is studying RTP incorporating a retransmission function.

The RTP incorporating the retransmission function under study will be described below with reference to FIGS. FIG. 14 is a configuration diagram of the moving image distribution system. 9, a wireless GW 1403 (relay device) receives a packet transmitted from a content distribution server (transmitting terminal) 1402 via a wired line, and receives the received packet via a wireless line. ) 1404. Note that the content distribution server 1402 distributes AV data or AV content stored on the disk 1401 in the form of an RTP packet.

[0006] The receiving terminal 1404 transmits data to the content distribution server 1402 by RTSP (Real-time Strea- ture).
ming Protocol). This is interpreted by the intervening wireless GW 1403, and transmitted as a data request from the wireless GW 1403 to the content distribution server 1402. The content distribution server 1402 is a wireless GW 140
3 and the wireless GW 1403 returns
A response is returned to 404. Content distribution server 1402
Transmits an RTP packet to the wireless GW 1403. The wireless GW 1403 transmits the received RTP packet to the receiving terminal 1404, and at the same time,
An RTP packet is temporarily stored in a memory or a hard disk in the server so that it can respond to a retransmission request from the receiving terminal 1404. Wireless GW1 from receiving terminal 1404
The retransmission request for 403 is transmitted by RTCP (Real-time Trans
port Control Protocol) packet. The reply to the RTCP packet from the wireless GW 1403 to the receiving terminal 1404 is not explicitly performed, but is performed implicitly in the form of transmission of a retransmission packet.

FIG. 15 is a diagram showing an example of the configuration of an RTP packet with a playback function transmitted from the content distribution server 1402. In the method using the RTP packet, an additional packet sequence number is defined, and is updated only in the case of a packet of high importance, so that the receiving terminal detects a loss of a packet containing important data, and The server can be notified of the retransmission request. The application of this method to a wireless network is under study. In FIG. 15, the RTP packet 1500 is S
QN (Sequence Number), TS (Timestamp), SSN (S
econd Sequence Number), DiffTS (Differential
Timestamp) and a payload (data) section. SQN is a sequence number that increases by one in packet units, TS is a time stamp indicating the display time of data included in the packet, S is 1 for packets with high importance, and 1 for other packets. Is a 1-bit flag in which 0 is set. SSN is a second sequence number that increases by 1 when S is 1. DiffTS is the TS of the current packet and the TS of the packet that was received before and whose S is 1.
This is the difference from.

FIG. 16 shows a content distribution server 1402.
Is a diagram when the RTP packets 1500 transmitted from the SQN = 1, 4, 7 are packets of high importance. In the packet sequence shown in FIG. 16, when a packet of SQN = 4 which is a packet of high importance and a packet of SQN = 5 which is a packet of low importance are not transmitted to the reception terminal 1404 due to packet loss, the reception terminal An operation in which 1404 requests wireless GW 1403 to retransmit a packet with SQN = 4 will be described below.

[0009] Receiving terminal 1404 first sets SQN = 4,5
Is lost during transmission. Then, when the packet of SQN = 6 is received, the SSN of the previously received packet of SQN = 3 is SSN = 1, whereas the SSN of the packet of SQN = 6 is SS
Since N = 2, it is detected that the SSN is increased by one. Further, since S of the packet of SQN = 6 is S = 0, it is detected that there is a packet of high importance at SQN = 4 or SQN = 5. Furthermore, SQN =
6 is DiffTS = 2000, and from the difference between TS and DiffTS, a packet of high importance is a packet of TS = 4000, that is, SQN =
4 is detected. From the above,
Receiving terminal 1404 issues a retransmission request for a packet with S = 1 and SSN = 2, that is, a packet with SQN = 4, if it is in time for decoding and display even after requesting retransmission of a packet of TS = 4000. , RTCP
This is performed by the wireless GW 1403 using a packet. Wireless GW1
403, upon receiving the retransmission request, S = 1 and SSN
= 2 packets are retransmitted.

FIG. 17 is a diagram showing an example of the configuration of an RTP packet with a playback function transmitted from the content distribution server 1402. In FIG. 17, RTP packet 1
Reference numeral 700 includes an RTP header section, an LP (Low Priority) header section, and a payload (data) section. The LP header is included only in RTP packets of low importance,
DSN (Differential Sequence) representing the difference between the SQN of the immediately preceding packet of high importance and the SQN of the current packet.
Number), and a DiffTS representing the difference between the TS of the immediately preceding packet of high importance and the TS of the current packet.

FIG. 18 shows a content distribution server 1402.
Is a diagram when the RTP packets 1700 transmitted from SQN = 1, 4, 7 are packets of high importance. In the packet sequence shown in FIG. 18, when a packet of SQN = 4 with high importance and a packet of SQN = 5 with low importance are not transmitted to the reception terminal 1404 due to packet loss, the reception terminal 1404
Retransmits SQN = 4, 5 packets to wireless GW 1403
The method of requesting is described below.

[0012] Receiving terminal 1404 first sets SQN = 4,5
Packet is lost during transmission, and since the DSN of the packet with SQN = 6 is DSN = 2, the packet with SQN = 4 is a packet of high importance from the difference between SQN and DSN. Is detected. From the above, if the receiving terminal 1404 requests the retransmission of the packet of SQN = 4, if it is in time for the decoding and display, the receiving terminal 1404 cannot receive the packet including the packet of SQN = 4, that is, SQN = A request for retransmission of packets 4 and 5 is made to the wireless GW 1403. Upon receiving the retransmission request, wireless GW 1403 retransmits SQN = 4, 5 packets.

[0013]

However, in the above-described conventional packet transmission method, packet loss occurring in a wired section between the content distribution server 1402 and the wireless GW 1403, the wireless GW 1403 and the receiving terminal 1
Both the packet loss occurring in the wireless section between the reception terminal 1404 and the reception terminal 1404 are detected without distinction.
For the packet loss in the wireless section, the wireless GW 140
Since the lost packet is stored in No.3, retransmission can be performed. However, for a packet loss in a wired section, the packet is not received even in the wireless GW 1403, so that the corresponding packet must be retransmitted. Can not. Therefore, the occurrence of a retransmission request for packet loss in a wired section is useless, and does not result in effective use of the bandwidth.

[0014] The packet loss occurring in the wired section and the packet loss occurring in the wireless section have different causes. Packet loss occurring in a wired section is basically due to congestion. On the other hand, packet loss occurring in a wireless section may be caused by congestion, but is usually radio interference. Congestion refers to a state in which the amount of data to be transmitted exceeds the transmission band. Therefore, if a retransmission request is made for a packet loss in a wired section, congestion will be further exacerbated.

Accordingly, it is an object of the present invention to provide a relay method and a relay apparatus in which a receiving terminal does not make a retransmission request for a packet loss in a wired section. In addition, when a loss of a packet with high importance is detected in a wired section, a reproduction request is not issued, and when a loss of a packet is detected in a wired section, a decoding mode of data included in the packet is set. It is an object of the present invention to provide a receiving terminal that switches between.

[0016]

A relay method according to a first aspect of the present invention receives a packet transmitted from a transmitting terminal via a wired line, and receives the received packet via a wireless line. A retransmission command transmitted in response to a retransmission instruction generated when a loss of a packet of high importance is detected by the header analyzing process in the receiving terminal. A packet retransmission step, analyzing a header of a packet transmitted from the transmitting terminal, and detecting a loss of a packet of high importance in a wired section in which the packet is transmitted by the wired line by analyzing the header; A header analysis correcting step of correcting the header so that the loss of the high-importance packet is not detected in the header analysis process at the receiving terminal. Characterized by comprising.

A relay method according to claim 2 of the present invention is a relay method for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to the receiving terminal via a wireless line. According to the header analyzing process at the receiving terminal, the first header information indicating the number of transmitted packets of high importance and the second header information specifying the display time of the high importance packets are respectively A packet retransmission step of retransmitting the retransmitted packet in response to a retransmission instruction generated when the inconsistency is detected; analyzing a header of a packet transmitted from the transmitting terminal; When a header analysis detects a loss of a packet of high importance in a wired section in which a packet is transmitted by the wired line, a header analysis process in the receiving terminal is performed. Characterized in that it comprises a header analysis correction step of correcting said first header information as inconsistent in the first header information is not detected by.

A relay method according to a third aspect of the present invention is a relay method for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to the receiving terminal via a wireless line. The first header information for specifying the sequence number of the packet with high importance and the second header information for specifying the display time of the packet with high importance are analyzed by the header analyzing process at the receiving terminal. A packet retransmission step of retransmitting the retransmission-instructed packet in response to a retransmission instruction generated when each inconsistency is detected, and analyzing a header of a packet transmitted from the transmitting terminal, When the header analysis detects a loss of a packet of high importance in a wired section in which a packet is transmitted by the wired line, the packet is transmitted to the receiving terminal. Missing high the importance packet at da analysis process, characterized in that it includes a header analysis correction step of deleting said first header information and the second header information so as not to be detected.

A relay method according to a fourth aspect of the present invention is a relay method for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to the receiving terminal via a wireless line. The first header information for specifying the sequence number of the packet with high importance and the second header information for specifying the display time of the packet with high importance are analyzed by the header analyzing process at the receiving terminal. A packet retransmission step of retransmitting the retransmission-instructed packet in response to a retransmission instruction generated when each inconsistency is detected, and analyzing a header of a packet transmitted from the transmitting terminal, When the header analysis detects a loss of a packet of high importance in a wired section in which a packet is transmitted by the wired line, the packet is transmitted to the receiving terminal. Inconsistency of the first header information by Da analysis process, characterized in that it includes a header analysis correction step of correcting the first header information so as not to be detected.

A relay device according to a fifth aspect of the present invention is a relay device for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to a receiving terminal via a wireless line. Packet retransmitting means for retransmitting the retransmitted packet in response to a retransmission instruction generated when a packet of high importance is detected by the header analyzing process at the receiving terminal, While analyzing the header of the packet transmitted from the transmitting terminal, the header analysis, when detecting the loss of a packet of high importance in the wired section in which the packet is transmitted by the wired line, the receiving terminal, Header analysis and correction means for correcting the header so that the loss of the packet of high importance is not detected in the header analysis processing.

A relay device according to claim 6 of the present invention is a relay device for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to a receiving terminal via a wireless line. According to the header analyzing process at the receiving terminal, the first header information indicating the number of transmitted packets of high importance and the second header information specifying the display time of the high importance packets are respectively In response to a retransmission instruction generated when inconsistency is detected, packet retransmission means for retransmitting a retransmission-instructed packet, and analyzing a header of a packet transmitted from the transmitting terminal, and When the header analysis detects a loss of a packet of high importance in a wired section in which a packet is transmitted by the wired line, the header analysis processing in the receiving terminal is performed. And having a header analyzing correction means contradiction of the first header information to modify the first header information so as not to be detected.

A relay device according to claim 7 of the present invention is a relay device for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to a receiving terminal via a wireless line. The first header information for specifying the sequence number of the packet with high importance and the second header information for specifying the display time of the packet with high importance are analyzed by the header analyzing process at the receiving terminal. In response to a retransmission instruction generated when each inconsistency is detected, packet retransmission means for retransmitting a retransmission-instructed packet, and analyzing a header of a packet transmitted from the transmitting terminal, By the header analysis,
When detecting a loss of a packet of high importance in a wire section where a packet is transmitted by the wire line, the header analysis processing at the receiving terminal is performed so that the loss of the packet of high importance is not detected. A header analysis and correction unit for deleting the first header information and the second header information.

A relay device according to claim 8 of the present invention is a relay device that receives a packet transmitted from a transmitting terminal via a wired line and transmits the received packet to a receiving terminal via a wireless line. The first header information for specifying the sequence number of the packet with high importance and the second header information for specifying the display time of the packet with high importance are analyzed by the header analyzing process at the receiving terminal. In response to a retransmission instruction generated when each inconsistency is detected, packet retransmission means for retransmitting a retransmission-instructed packet, and analyzing a header of a packet transmitted from the transmitting terminal, By the header analysis,
When detecting a loss of a packet of high importance in a wired section in which a packet is transmitted by the wired line, the inconsistency of the first header information is not detected in a header analysis process in the receiving terminal. And a header analysis and correction means for correcting the first header information.

According to a ninth aspect of the present invention, there is provided a receiving terminal, comprising: first header information indicating the number of transmitted packets of high importance;
And receiving a packet including second header information for specifying the display time of the packet of high importance, performing a decoding process on data included in the packet, and
When both the header information and the second header information are inconsistent, a request for retransmission of a packet including the header information is received, the receiving means receiving the packet, and the receiving means And a decoding unit for decoding data included in the packet received by the receiving unit. The header analyzing unit includes: And analyzing the header information and the second header information, and instructing the decoding means on the decoding method of the data included in the packet including the header information.

[0025] According to a tenth aspect of the present invention, in the receiving terminal according to the ninth aspect, the header analyzing means is configured to determine that the second header information is inconsistent and the first header information is inconsistent. If not, an instruction is given to the decoding means so as not to decode the data included in the packet including the header information.

[0026] The receiving terminal according to claim 11 of the present invention comprises: first header information for specifying a sequence number of a packet of high importance; and second header information for specifying a display time of a packet of high importance. Receiving the packet including the packet, performing decoding processing on the data included in the packet, and when both the first header information and the second header information are inconsistent, the packet including the header information Receiving means for receiving the packet, header analyzing means for analyzing header information contained in the packet received by the receiving means, and receiving by the receiving means Decoding means for decoding data contained in the packet, wherein the header analysis means analyzes the first header information and the second header information, Characterized by instructing the decoding method of the data contained in the packet including these header information to the decoding means.

[0027] According to a twelfth aspect of the present invention, in the receiving terminal according to the eleventh aspect, the header analyzing means may be configured such that the second header information is inconsistent and the first header information is inconsistent. If not, an instruction is given to the decoding means so as not to decode the data included in the packet including the header information.

[0028]

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of a wireless GW 100 according to Embodiment 1 of the present invention. The wireless GW 100 (relay device) receives a packet transmitted from the content distribution server (transmission side terminal) via a wired line, and transmits the received packet to a reception terminal (reception side terminal) via a wireless line. Device. The content distribution server distributes AV data or AV content in the form of RTP packets.

The wireless GW 100 analyzes the received packet buffer 11 for storing the received packet and the header of the received packet to determine whether a packet of high importance has been lost. A header analysis and correction unit 12 for correcting the header of the packet so that the receiving terminal does not detect the fact and request for retransmission, a transmission packet buffer 13 for storing the packet from the header analysis and correction unit 12 as a transmission packet,
A packet sending unit 14 for sending a packet stored in the sending packet buffer 13; and a retransmission request receiving unit 15 for receiving a retransmission request RTCP packet from the receiving terminal.
And packet clear means 16 for instructing the transmission packet buffer 13 to discard packets older than a certain time. The clock 17 supplies an operation clock to each unit. Further, when receiving a retransmission request instruction from the retransmission request receiving unit 15, the packet transmitting unit 14 converts the packet to the operation clock supplied from the clock 17 if a packet corresponding to the packet remains in the transmission packet buffer 13. Resend based on.

The wireless GW 100 configured as described above
However, the operation when receiving the RTP packet 1500 as shown in FIG. 15 will be described below. Wireless GW10
When the RTP packet 1500 is received, the header analysis / correction unit 12 analyzes the S and SSN included in the header of the received packet, checks the difference between the SSN of the header of the packet received immediately before, and S When S = 0, SSN
If the SSN has increased by one, or if the SSN has increased by two or more, the SSN and DiffTS are corrected.

For example, the RTP packet 1500 transmitted from the content distribution server becomes a packet sequence as shown in FIG. 2A, and the packet received by the wireless GW 100 becomes a packet sequence as shown in FIG. The following is a description. In this case, since SQN = 1, 4, and 7 are packets of high importance and packets of SQN = 4 and 5 are lost in the wired section, the wireless GW 100 is configured as shown in FIG.
Is transmitted to the receiving terminal, the receiving terminal detects that the packet of SQN = 4 lost during transmission is a packet of high importance, and if S = 1 and SSN
= 2, that is, a retransmission request for a packet with SQN = 4. Here, the receiving terminal determines that the packet of SQN = 6 is S = 0 and SSN = 2, whereas the packet of SQN = 3 received immediately before is S = 0 and SSN = 2. = 1 and the difference between the TS and the DiffTS of the packet of SQN = 6 is 4000, so that the packet of SQN = 4 lost during transmission is detected as a packet of high importance. Therefore, the header analysis correcting means 12 corrects the SSN = 2 of the packet of SQN = 6 to SSN = 1, and corrects the SSN of SQN = 3 and SQN = 6.
Is changed to the same value, and the SSN of subsequent packets of SQN = 7 to SQN = 9 is corrected from SSN = 3 to SSN = 2. Accordingly, the TS of the packet of SQN = 6
And the difference between the TS of the packet with SQN = 1 and SQ
The DiffTS of the packet with N = 6 is changed to DiffTS = 50.
00, and the TS of the packet with SQN = 7 and the SQN
The difference from the TS of the packet of = 1 is obtained, and the DiffTS of the packet of SQN = 7 is corrected to DiffTS = 6000. The packet corrected as described above and transmitted from the wireless GW 100 becomes a packet sequence as shown in FIG. As described above, when the wireless GW 100 detects that a packet of high importance has been lost in the wired section, the wireless GW 100 corrects the SSN and DiffTS included in the packet to make them continuous so that the receiving terminal can In a wired section, loss of a packet of high importance cannot be detected, and a retransmission request for the packet is not issued.

Also, the packet transmitted from the content distribution server becomes a packet sequence as shown in FIG.
A case where a packet received by the wireless GW 100 is a packet sequence as shown in FIG. 3B will be described. In this case, the important data is divided into packets of SQN = 4 to SQN = 6, and the packet of SQN = 5 is lost in the wired section.
Transmits the packet sequence shown in FIG. 3 (b) to the receiving terminal,
The receiving terminal detects that SQN = 5 lost during transmission is a packet of high importance, and if S = 1 and SSN
= 3 packets may be transmitted. That is, the receiving terminal converts the packet of SQN = 6 into S
SQ received just before SN = 2
Since the packet of N = 3 is SSN = 4, it is detected that the packet of SQN = 5 lost during transmission is a packet of high importance. Therefore, header analysis means 1
2 is the SSN of SQN = 6 from SSN = 4 to SSN = 3
, And the following SSN of SQN = 7,8
N = 4 to SSN = 3, and SSN of SQN = 9 to S
Modify SN = 5 to SSN = 4. By modifying the packet as described above, the packet sequence transmitted from the wireless GW 100 becomes a packet sequence as shown in FIG. Thus, the wireless GW 100 loses SQN = 5 in the wired section.
Is not detected by the receiving terminal as a packet of high importance, S = 1 and SSN
= 3, that is, a packet of SQN = 5 is not generated.

Also, for example, a packet transmitted from the content distribution server becomes a packet sequence as shown in FIG. 4A, and a packet received by the wireless GW 100 is
If the packet sequence is as shown in (b), SQN = 4
Is lost in the wired section, but the SQN
= 4 is a packet of low importance, the wireless GW 100 determines the S
No modification is made to SN and DiffTS. Therefore, the transmission packet sequence from the wireless GW 100 becomes a packet sequence as shown in FIG.

As described above, according to the first embodiment, the wireless GW 100 analyzes the S and SSN of the header of the RTP packet 1500 transmitted from the content distribution server by the header analysis and correction means 12 and immediately before The difference between the received packet and the SSN is checked, and when S is 0, if the SSN is increased by 1 or if the SSN is increased by 2 or more,
Since the packet in which the SSN and DiffTS have been modified is transmitted to the receiving terminal, even when a packet of high importance is lost in the wired section, a useless retransmission request for the packet is made to the wireless GW 100 from the receiving terminal. And the band can be used effectively.

(Second Embodiment) In the first embodiment, when the header analysis and correction means 12 of the wireless GW 100 detects that a packet of high importance has been lost in the wired section, it corrects the SSN and DiffTS of the header. However, in the second embodiment, the header analysis / correction unit 12
An embodiment in which only N is corrected will be described.

For example, the RTP packet 1500 transmitted from the content distribution server becomes a packet sequence as shown in FIG. 5A, and the packet received by the wireless GW 100 becomes a packet sequence as shown in FIG. Will be described. In this case, since SQN = 1, 4, 7 are packets with high importance and packets with high importance SQN = 4 are lost in the wired section, the header analysis / correction means 12 of the wireless GW 100 uses SQN = 5 , SS of packet 6
N is modified from SSN = 2 to SSN = 1, and SQN = 3
And SQN = 5, 6 have the same value in SSN,
SSN = 3 for the SSN of the packet with QN = 7 to SQN = 9
To SSN = 2 and SSN of SQN = 10,11 to SS
Modify N = 4 to SSN = 3. At that time, SQN =
The 5, 6, and 7 DiffTSs are not modified. The packet sequence corrected in this way and transmitted to the receiving terminal is a packet sequence as shown in FIG.

FIG. 6 shows receiving terminal 2 according to the second embodiment.
FIG. 2 is a block diagram showing a configuration of a 00. In FIG. 6, a receiving terminal 200 includes a receiving unit 21 and a receiving buffer 22.
RTP packet analyzing means 23, decoding means 24,
A display unit 25, a retransmission request unit 26, a header analysis unit 27, and a frame memory 28 are provided.

Receiving means 21 receives the RTP packet, examines S and SSN included in the header of the received RTP packet, and detects a loss of a packet of high importance, and detects a lost packet of high importance. SS
N37 is notified to the retransmission request unit. Receive buffer 22
Stores the received RTP packet.

The RTP packet analysis means 23 receives the data request instruction signal 33 from the decoding means 24, reads an RTP packet for one VOP from the reception buffer 22,
The TP packet header 35 is output to the header analysis means 27. At this time, the header analysis unit 27 checks S, SSN, DiffTS included in the header, and outputs a decoding instruction mode signal 34 to the RTP packet analysis unit 23 based on the analysis result. Then, the RTP packet analyzing means 23
Outputs the encoded video data 31 read from the reception buffer 22 and the decoding instruction mode signal 34 to the decoding means 24.

The decoding means 24 outputs the encoded video data 31
Is decoded based on the decoding instruction mode signal 34. The video decoded data 36 is stored in the frame memory 28 for reference.
Are stored as data. The display means 25 displays the video-decoded data 32. The retransmission request unit 26 forms an RTCP packet for a retransmission request and transmits the RTCP packet to the wireless GW 100.

An operation when the receiving terminal 200 configured as described above receives a packet sequence as shown in FIG. 5C will be described. Upon receiving the packet, the receiving terminal 200 uses the header analysis unit 27 to decode S, S of the header of the packet before decoding video encoded data included in the packet.
Check the SSN, DiffTS. Header analysis means 27
Is that the relationship between TS and DiffTS is from SQN = 1 to S
Since there is no inconsistency up to QN = 3 and there is inconsistency from SQN = 5, it is detected that the packet of SQN = 4 lost in the wired section is a packet of high importance. However, in this case, even if the receiving terminal 200 detects that the packet of SQN = 4 lost in the wired section is a packet of high importance, the SGW of the packet of SQN = 5 or later is corrected in the wireless GW 100. Therefore, S = 1,
No retransmission request is made for a packet with SSN = 2, that is, a packet with SQN = 4.

Further, the header analyzing means 27 converts the decoding mode instruction signal 34 into an RTP based on the analysis result of the header.
The data is output to the decoding means 24 via the packet analysis means 23 to instruct the decoding mode of the video encoded data.

Hereinafter, an example of decoding video encoded data when it is detected that a packet of high importance has been lost in a wired section will be described with reference to FIGS. 7 and 8
, CT is a code indicating how the VOP is coded, ie, how the VOP is coded, read by the RTP packet analysis means 23, I is intra-frame coding, and P is inter-frame forward prediction coding. , B indicate that the VOP is encoded by bidirectional predictive encoding.

First, the case where the header analysis means 27 instructs the decoding means 24 by the decoding mode instruction signal 34 whether or not to decode the VOP included in the packet whose header has been analyzed will be described with reference to FIG. I do. In FIG. 7, "0" is assigned to the VOP of the packet to be decoded, X is assigned to the VOP of the packet not to be decoded, and "-" is assigned to the packet lost in the wired section. Here, a packet of SQN = 4, which is a packet of high importance, is lost in the wired section. As shown in FIG. 7, the VOP of SQN = 4 is used as a reference image for VOPs of packets of SQN = 5 to SQN = 9. If the packet of SQN = 4 has not been lost in the wired section, the receiving terminal 200
= 5,6 are VOPs of SQN = 1,4, SQN
= 7 is the VOP of SQN = 4, SQN = 8,9
Decodes VOPs of SQN = 4, 7 as reference images. On the other hand, if the packet of SQN = 4 is lost in the wired section and the wireless GW 100 corrects the SSN and DiffTS as in the first embodiment, the receiving terminal 200
Are VOPs of SQN = 5 and 6 are SQN = 1 and SQN = 1
The previous P-VOP, the VOP of SQN = 7 is SQ
The VOP of N = 1 and the VOP of SQN = 8, 9 are SQN =
The VOPs 1, 7 are decoded as reference images.
Therefore, as compared with the case where the packet of SQN = 4 has not been lost, the temporally distant VOP is used as the reference image, and the decoded image may be disturbed. Therefore,
The header analysis means 27 has SQN = 1 to SQN = 3, SQN
= 10 and 11 are decoded, but SQN = 5 to S
An instruction not to decode the packet of QN = 9 is output as a decoding mode instruction signal 34.

The decoding mode instruction signal 34 is sent to the decoding means 24 via the RTP packet analysis means 23, and the decoding means 24 decodes the VOP, that is, the encoded video data 31, based on the decoding mode instruction signal 34.

Next, a case where the header analysis means 27 designates a reference image of a VOP to be decoded by the decoding mode instruction signal 34 will be described with reference to FIG. In this case, the header analysis unit 27 outputs an instruction to use a decoded image that is closer in time as a reference image as the decoding mode instruction signal 34. For example, as shown in FIG.
In the case where the packet of SQN = 4 is not lost in the wired section, VOP = 4,7 is decoded as the reference image, whereas the packet of SQN = 4 is lost in the wired section, and SSN, Di in the wireless GW 100 as in 1.
Assuming that the ffTS has been corrected, VOPs with SQN = 1, 7 are decoded as reference images. Therefore, the header analysis unit 27 instructs to decode the VOP of SQN = 8 as a VOP closer in time as a reference image, that is, decodes the already decoded VOP of SQN = 3 as a reference image. Instruction to the decoding mode instruction signal 34
Output as

The decoding mode instruction signal 34 is sent to the decoding means 24 via the RTP packet analysis means 23, and the decoding means 24 decodes the VOP, that is, the encoded video data 31, based on the decoding mode instruction signal 34.

As described above, according to the second embodiment, the wireless GW 100 analyzes the S and SSN of the header of the RTP packet 1500 transmitted from the content distribution server by the header analysis and correction means 12 and immediately before The difference between the received packet and the SSN is checked, and when S is 0, if the SSN has increased by 1 or if the SSN has increased by 2 or more, the importance of the receiving terminal 200 in the wired section is determined. When only the SSN is modified so that a retransmission request is not generated even if a loss of a packet having a high packet is detected, the receiving terminal 200 analyzes the header of the received packet, and decodes the data included in the packet obtained by analyzing the header. Since the decoding mode of the data is switched based on the result of the header analysis, when an important packet is lost in the wired section, the receiving terminal transmits the packet to the wireless GW. It is possible to effectively use the bandwidth as is not performed useless retransmission request for the packet Te, decoded at the receiving terminal, it is possible to prevent disorder of the image to be displayed.

(Embodiment 3) In Embodiment 3, an example in which the wireless GW 100 receives an RTP packet 1700 as shown in FIG. 17 will be described.
Upon receiving the RTP packet 1700, the wireless GW 100 analyzes the RTP header and the LP header included in the packet received by the header analysis correcting unit 12.

For example, the RTP packet 1700 transmitted from the content distribution server becomes a packet sequence as shown in FIG. 9A, and the packet received by the wireless GW 100 becomes a packet sequence as shown in FIG. 9B. Will be described. In this case, the packets of SQN = 1, 4, 7 are packets of high importance, and SQN
= 4 and 5 packets have been lost, the wireless GW
When 100 transmits a packet sequence as shown in FIG. 9B to the receiving terminal, the receiving terminal detects that the packet of SQN = 4 lost during transmission is a packet of high importance,
There is a possibility that a retransmission request for packets of SQN = 4, 5 will be made. That is, the receiving terminal detects that the packets of SQN = 4, 5 have been lost, and the DSN of the packet of SQN = 6 is DSN = 2.
, It is detected that the packet of SQN = 4 is a packet of high importance. Therefore, the header analysis correction unit 12 converts the DSN of SQN = 6 from DSN = 2 to DSN
= 5, DiffTS is changed from DiffTS = 2000 to D
Correct to ifTS = 5000. By performing such correction, even if the receiving terminal receives the packet of SQN = 6, the packet of SQN = 1 is regarded as the immediately preceding packet of high importance, and the retransmission request for SQN = 4,5 Does not occur. Modified as above, wireless G
The packet transmitted from W100 is a packet sequence as shown in FIG.

As described above, according to the third embodiment, the wireless GW 100 determines whether the RTP header included in the RTP packet 1700 transmitted from the content distribution server
The P header is analyzed by the header analysis and correction means 12, and when it is detected that a packet of high importance is lost in the wired section from the difference between the SQN and the DSN, the DSN and DiffTS are corrected and the packet is transmitted to the receiving terminal. Thus, even when a packet of high importance is lost in the wired section, it is possible to prevent the receiving terminal from making useless retransmission requests for the packet to the wireless GW, and to effectively use the band. It can be used.

(Embodiment 4) In Embodiment 3 described above,
When a loss of a packet of high importance occurs in the wired section, the wireless GW 100 uses the DSN included in the LP header to prevent the receiving terminal from generating a retransmission request.
In the fourth embodiment, an example in which the LP header is deleted will be described.

For example, as shown in FIG. 10B, when a packet of SQN = 4 of high importance and a packet of SQN = 5 of low importance are lost in the wired section, the wireless GW 100
Deletes the LP header of the packet of SQN = 6. By deleting such LP header, DSN of SQN = 6
And DiffTS are deleted, and the packet transmitted from the wireless GW 100 becomes a packet sequence as shown in FIG. Therefore, the receiving terminal regards the packet of SQN = 6 as a packet of high importance, and does not generate a retransmission request for SQN = 4, 5.

As described above, according to the fourth embodiment, the wireless GW 100 transmits the RTP header included in the RTP packet 1700 transmitted from the content distribution server,
The P header is analyzed by the header analysis / correction unit 12, and when a loss of a packet of high importance in the wired section is detected from the difference between the SQN and the DSN, the L including the DSN and the DiffTS is detected.
Since the P header is deleted and the packet is transmitted to the receiving terminal, even when a packet of high importance is lost in the wired section, a useless retransmission request for the packet is sent from the receiving terminal to the wireless GW. This can be easily prevented without modifying the DSN and DiffTS, and the band can be used effectively.

In FIG. 10, assuming that SQN = 7,8 is a low-priority packet and SQN = 9 is a high-priority packet, the LP header of the SQN = 7,8 packet is also deleted. And sends it to the receiving terminal.

(Fifth Embodiment) In the third embodiment, when the wireless GW 100 detects that a packet of high importance has been lost in a wired section, the DSN of the LP header is detected.
In the fifth embodiment, an example in which the wireless GW 100 modifies only the DSN will be described.

For example, the RTP packet 1700 transmitted from the content distribution server becomes a packet sequence as shown in FIG. 11A, and the packet received by the wireless GW 100 becomes a packet sequence as shown in FIG. , The packet with the high importance SQN = 4 is lost in the wired section.
2 is the DSN of SQN = 5, DSN = 1 to DSN = 4
Then, the DSN of SQN = 6 is modified from DSN = 2 to DSN = 5. At this time, DiffTS of SQN = 5, 6 is not modified. The packet corrected in this way and transmitted to the receiving terminal becomes a packet sequence as shown in FIG.

Hereinafter, the operation of the receiving terminal 200 when receiving a packet in which only the DSN is modified as shown in FIG. 11C will be described below. Upon receiving the packet, the receiving terminal 200 first checks the SQN, DSN, and DiffTS included in the packet by the header analysis unit 27. The header analysis unit 27 detects that the packet of SQN = 4 has been lost during transmission, and the packets of SQN = 5, 6 have no contradiction in DSN but have inconsistency in DiffTS. The lost SQN = 4 packet has high importance, and detects that it has been lost in the wired section. However, in this case, since there is no inconsistency in DSN, receiving terminal 200 has lost SQN = 4 in the wired section.
Do not request resending.

Further, the header analyzing means 27 outputs a decoding mode instruction signal 34 to the decoding means 24 via the RTP packet analyzing means 23 based on the result of the header analysis, and instructs a decoding mode of the encoded video data. .

Hereinafter, the SQN which is a packet of high importance
FIG. 1 shows a decoding example of video coded data (VOP) when it is detected that a packet of = 4 has been lost in a wired section.
This will be described with reference to FIGS. The signs of CT, I, B, P, 0, X, and − assigned to the packet strings in FIGS. 12 and 13 have the same meanings as those assigned to the packet strings in FIGS. The description is omitted as it has.

As shown in FIG. 12, the VOP of SQN = 4 is used as the reference image because the VOP of SQN = 5 to SQN = 9 is used.
It is. If the packet of SQN = 4 has not been lost in the wired section, the receiving terminal 200 transmits the VOP of SQN = 5,6.
Is the VOP of SQN = 1,4, and the VOP of SQN = 7 is
The VOP of SQN = 4 and the VOP of SQN = 8, 9
The VOP of QN = 4, 7 is decoded as a reference image. On the other hand, the packet of SQN = 4 is lost in the wired section, and the wireless GW 100 causes the DSN, Di as in the third embodiment.
When the ffTS is modified, the receiving terminal 200 sets the SQN =
The VOPs of 5 and 6 are SQN = 1 and the P-VOP one step before SQN = 1, and the VOP of SQN = 7 is the VON of SQN = 1.
P is the VOP of SQN = 8,9 is the VO of SQN = 1,7.
P will be decoded as a reference image. Therefore,
Compared to the case where the packet of SQN = 4 is not lost, a temporally distant VOP is used as the reference image, and the decoded image may be disturbed. Therefore, the header analysis unit 27 issues an instruction to decode the packets of SQN = 1 to SQN = 3 and SQN = 10 and 11 but not to decode the packets of SQN = 5 to SQN = 9, and issue the decoding mode instruction signal 34.
Output as

The decoding mode instruction signal 34 is sent to the decoding means 24 via the RTP packet analyzing means 23, and the decoding means 24 decodes the VOP, that is, the encoded video data 31, based on the decoding mode instruction signal 34.

Next, a case where the header analysis means 27 designates the reference picture of the VOP to be decoded by the decoding mode instruction signal 34 will be described with reference to FIG. In this case, the header analysis unit 27 outputs an instruction to use a decoded image that is closer in time as a reference image as a decoding mode instruction signal.
For example, as shown in FIG. 13, SQN = 8 becomes SQN =
If the packet No. 4 has not been lost in the wired section, the VO
While P = 4 and 7 are decoded as reference images, when DSN and DiffTS are corrected as in the third embodiment, VOPs with SQN = 1 and 7 are decoded as reference images. Therefore, the header analysis means 27 calculates the SQN =
An instruction to decode the VOP of No. 8 as a VOP closer in time as a reference image is output as a decoding mode instruction signal. That is, an instruction to decode the VOP of SQN = 8 as the already decoded VOP of SQN = 3 is output as the decoding mode instruction signal 34.

The decoding mode instruction signal 34 is sent to the decoding means 24 via the RTP packet analyzing means 23, and the decoding means 24 decodes the VOP, that is, the video coded data 31, based on the decoding mode instruction signal 34.

As described above, according to the fifth embodiment, wireless GW 100 transmits R
The SQN and DSN contained in the LP header of the TP packet 1700 are analyzed by the header analysis and correction means 12, and the SQN and D
If it is detected from the difference in SN that a packet of high importance has been lost in the wired section, it is detected that the important packet has been lost in the wired section in the receiving terminal 200, but a retransmission request is not made. Modify only DSN,
The receiving terminal 200 analyzes the header of the received packet,
When decoding data included in the packet whose header has been analyzed, the decoding mode of the data is switched based on the result of the header analysis. Wireless GW
In addition, it is possible to effectively use the band by preventing a useless retransmission request for the packet from being made, and to prevent disturbance of the image decoded and displayed by the receiving terminal.

[0066]

As described above, according to the relay method of the first aspect, when the header of the packet transmitted from the transmitting terminal is analyzed and a loss of a highly important packet in the wired section is detected. Is that the header is corrected so that the loss of the packet of high importance in the wired section is not detected by the receiving terminal, so that the waste of the loss of the packet of high importance in the wired section at the receiving terminal is corrected. A retransmission request can be prevented from being generated, and the bandwidth can be used effectively.

According to the relay method of the second aspect,
Analyze the header of the packet sent from the sending terminal,
When detecting that the first header information indicating the number of transmitted packets of high importance included in the header and the second header information specifying the display time of the packet of high importance are inconsistent, Since the inconsistency of the first header information is corrected so that the receiving terminal does not generate a retransmission request for a packet of high importance lost in the wired section, the receiving terminal has high importance in the wired section. Even if a packet loss is detected, a useless retransmission request for the packet can be prevented from being generated, and the bandwidth can be used effectively.

According to the relay method of the third aspect,
Analyze the header of the packet sent from the sending terminal,
When it is detected that the first header information for specifying the sequence number of the packet of high importance included in the header and the second header information for specifying the display time of the packet of high importance are inconsistent. The first header information and the second header information so that a retransmission request for a packet of high importance lost in a wired section is not generated at a receiving terminal.
Since the header information is deleted, it is possible to prevent a useless retransmission request for a loss of a packet of high importance in a wired section from being generated at the receiving terminal without correcting the header information, The bandwidth can be used effectively.

According to the relay method of the fourth aspect,
Analyze the header of the packet sent from the sending terminal,
When it is detected that the first header information for specifying the sequence number of the packet of high importance included in the header and the second header information for specifying the display time of the packet of high importance are inconsistent. Since the inconsistency of the first header information is corrected so that a request for retransmission of a packet of high importance lost in the wired section at the receiving terminal is not generated, the importance of the packet in the wired section at the receiving terminal is corrected. Even if a loss of a packet having a high packet loss is detected, a useless retransmission request for the packet can be prevented from being generated, and the bandwidth can be used effectively.

Further, according to the relay device of the fifth aspect,
While analyzing the header of the packet transmitted from the transmitting side and detecting the loss of a packet with high importance in the wired section, the loss of the packet with high importance in the wired section is not detected by the receiving terminal. Is provided with a header analysis correcting means for correcting the header, so that a useless retransmission request for a loss of a packet of high importance in a wired section can be prevented from being generated at the receiving terminal, and effective use of bandwidth can be prevented. It becomes possible.

According to the relay device of the sixth aspect,
Analyze the header of the packet sent from the sending terminal,
When detecting that the first header information indicating the number of transmitted packets of high importance included in the header and the second header information specifying the display time of the packet of high importance are inconsistent, Since the receiving terminal is provided with a header analysis correcting means for correcting the inconsistency of the first header information so as not to generate a retransmission request for a packet of high importance lost in the wired section at the receiving terminal, Even if a loss of a packet with high importance is detected, a useless retransmission request for the packet can be prevented from being generated, and the bandwidth can be used effectively.

According to the relay device of the seventh aspect,
Analyze the header of the packet sent from the sending terminal,
When it is detected that the first header information for specifying the sequence number of the packet of high importance included in the header and the second header information for specifying the display time of the packet of high importance are inconsistent. The first header information and the second header information so that a retransmission request for a packet of high importance lost in a wired section is not generated at a receiving terminal.
The header analysis correction means for deleting the header information of the packet, prevents the receiving terminal from generating a useless retransmission request for a loss of a packet of high importance in the wired section without correcting the header information. And the bandwidth can be used effectively.

Further, according to the relay device of claim 8,
Analyze the header of the packet sent from the sending terminal,
When it is detected that the first header information for specifying the sequence number of the packet of high importance included in the header and the second header information for specifying the display time of the packet of high importance are inconsistent. Since the receiving terminal includes a header analysis and correction unit that corrects the inconsistency of the first header information so that a retransmission request for a packet of high importance lost in the wired section is not generated, Thus, even if a loss of a packet of high importance is detected, a useless retransmission request for the packet can be prevented from being generated, and the bandwidth can be used effectively.

According to the receiving terminal of the ninth aspect,
Receiving means for receiving a packet, header analyzing means for analyzing a header of the received packet, and decoding means for decoding data stored in the packet, wherein the header analyzing means determines the number of transmitted packets of high importance. The header including the first header information to be displayed and the second header information for specifying the display time of the packet with high importance is analyzed, and the data included in the packet including the header information is analyzed based on the analysis result. Since the decoding method is instructed to the decoding means, it is possible to detect a loss of a packet of high importance in a wired section and prevent an image to be decoded and displayed from being disturbed.

According to a tenth aspect of the present invention, in the receiving terminal according to the ninth aspect, the header analyzing means determines that the second header information is inconsistent and the first header information is inconsistent. When there is no inconsistency, an instruction is given to the decoding means so as not to decode the data included in the packet including the header information. Can be detected, and the image to be decoded and displayed can be prevented from being disturbed.

According to the receiving terminal of the present invention, a receiving means for receiving a packet, a header analyzing means for analyzing a header of the received packet, and a decoding for decoding data stored in the packet. Means, the header analysis means analyzes a header including first header information specifying a sequence number of a packet of high importance and second header information specifying a display time of a packet of high importance, Since the decoding means is instructed to the decoding means based on the analysis result for the data included in the packet including the header information, the loss of a highly important packet in the wired section can be detected. In addition, the image to be decoded and displayed can be prevented from being disturbed.

Further, according to the receiving terminal of the present invention, in the receiving terminal of the present invention, the header analyzing means may determine that the second header information is inconsistent and the first header information is inconsistent. When the header information is not inconsistent, an instruction is given to the decoding means so as not to decode the data included in the packet including the header information. Packet loss can be detected, and the image to be decoded and displayed can be prevented from being disturbed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a wireless GW according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a packet sequence of a packet relayed by a wireless GW of the present invention between a content distribution server on a transmission side and a reception terminal on a reception side, wherein (a) shows a transmission packet sequence of the content distribution server; b) is a wireless GW received packet sequence, and (c)
Is a transmission packet sequence of the wireless GW.

FIG. 3 is a diagram showing a packet sequence of packets relayed by the wireless GW of the present invention between a content distribution server on the transmission side and a reception terminal on the reception side, where (a) shows a transmission packet sequence of the content distribution server; b) is a wireless GW received packet sequence, and (c)
Is a transmission packet sequence of the wireless GW.

FIG. 4 is a diagram showing a packet sequence of a packet relayed by the wireless GW of the present invention between a content distribution server on the transmission side and a reception terminal on the reception side, where (a) shows a transmission packet sequence of the content distribution server, b) is a wireless GW received packet sequence, and (c)
Is a transmission packet sequence of the wireless GW.

FIG. 5 is a diagram showing a packet sequence of packets relayed by the wireless GW of the present invention between a content distribution server on the transmission side and a reception terminal on the reception side, where (a) shows a transmission packet sequence of the content distribution server; b) is a wireless GW received packet sequence, and (c)
Is a transmission packet sequence of the wireless GW.

FIG. 6 is a block diagram showing a configuration of a receiving terminal according to Embodiment 2 of the present invention.

FIG. 7 is a diagram for explaining a data decoding method in the receiving terminal of the present invention.

FIG. 8 is a diagram for explaining a data decoding method in the receiving terminal of the present invention.

FIG. 9 is a diagram showing a packet sequence of packets relayed by the wireless GW of the present invention between the content distribution server on the transmitting side and the receiving terminal on the receiving side, where (a) shows a transmission packet sequence of the content distribution server, b) is a wireless GW received packet sequence, and (c)
Is a transmission packet sequence of the wireless GW.

FIG. 10 is a diagram showing a packet sequence of packets relayed by the wireless GW of the present invention between a content distribution server on the transmission side and a reception terminal on the reception side, where (a) shows a transmission packet sequence of the content distribution server, b) is a wireless GW received packet sequence,
(c) is a transmission packet sequence of the wireless GW.

FIG. 11 is a diagram showing a packet sequence of packets relayed by the wireless GW of the present invention between the content distribution server on the transmission side and the reception terminal on the reception side, where (a) shows a transmission packet sequence of the content distribution server; b) is a wireless GW received packet sequence,
(c) is a transmission packet sequence of the wireless GW.

FIG. 12 is a diagram for explaining a data decoding method in the receiving terminal of the present invention.

FIG. 13 is a diagram for explaining a data decoding method in the receiving terminal of the present invention.

FIG. 14 is a diagram illustrating a configuration of a general moving image distribution system.

FIG. 15 is a diagram showing a configuration of an RTP packet with a retransmission function.

16A and 16B are diagrams showing a packet sequence of a packet relayed by a conventional wireless GW between a content distribution server on the transmission side and a reception terminal on the reception side, where FIG. 16A shows a transmission packet sequence of the content distribution server, and FIG. ) Is a received packet sequence of the wireless GW.

FIG. 17 is a diagram showing a configuration of an RTP packet with a retransmission function.

FIG. 18 is a diagram showing a packet sequence of packets relayed by a conventional wireless GW between a content distribution server on the transmission side and a reception terminal on the reception side, where (a) shows a transmission packet sequence of the content distribution server and (b) ) Is a received packet sequence of the wireless GW.

[Explanation of symbols]

 Reference Signs List 11 reception packet buffer 12 header analysis correction means 13 transmission packet buffer 14 packet transmission means 15 packet clear means 16 retransmission request reception means 17 clock 21 reception means 22 reception buffer 23 RTP packet analysis means 24 decoding means 25 display means 26 retransmission request means 27 Header analysis means 28 Frame memory 1401 Disk 1402 Content distribution server 1403,100 Wireless GW 1404,200 Receiving terminal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 29/08 H04L 13/00 307Z (72) Inventor Takao Yamaguchi 1006 Kazuma Kazuma Kadoma City, Osaka Matsushita Electric Industrial (72) Inventor Tomoyoshi Ito 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Junichi Sato 1006 Okadoma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 5B089 GA31 GB02 HA11 KA12 KE01 ME08 5K030 GA08 GA11 HA08 HB02 HB17 HD01 HD05 HD06 JL01 LA01 MB13 5K033 BA13 CB03 CB08 CC01 DA05 DA17 DB18 5K034 CC02 EE03 HH11 MM03 MM22

Claims (12)

[Claims] 1. A relay method for receiving a packet transmitted from a transmitting terminal via a wired line, and transmitting the received packet to the receiving terminal via a wireless line, comprising: a header at the receiving terminal. A packet retransmission step of retransmitting a retransmission-instructed packet in response to a retransmission instruction generated when a loss of a packet of high importance is detected by the analysis processing of: a header of a packet transmitted from the transmitting terminal. When the header analysis detects a loss of a packet of high importance in a wired section in which a packet is transmitted by the wired line, the header analysis processing in the receiving terminal performs the header analysis. A header analysis correction step of correcting the header so that a high packet loss is not detected. 2. A relay method for receiving a packet transmitted from a transmitting terminal via a wired line, and transmitting the received packet to a receiving terminal via a wireless line, comprising: a header at the receiving terminal. The first header information indicating the number of transmitted packets of high importance and the second header information specifying the display time of the packets of high importance are detected by the analysis processing of A packet retransmission step of retransmitting the packet instructed to be retransmitted in response to the retransmission instruction generated in step (a), analyzing the header of the packet transmitted from the transmitting terminal, and analyzing the header, the When detecting the loss of a packet of high importance in the transmitted wired section, the header analysis processing at the receiving terminal causes inconsistency in the first header information. Relay method which comprises a header analysis correction step of correcting the first header information so as not to be detected. 3. A relay method for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to a receiving terminal via a wireless line, wherein the header at the receiving terminal is Is analyzed, it is detected that the first header information for specifying the sequence number of the packet of high importance and the second header information for specifying the display time of the packet of high importance are inconsistent with each other. A packet retransmission step of retransmitting a packet instructed to be retransmitted in response to a retransmission instruction that is sometimes generated, and analyzing a header of a packet transmitted from the transmitting terminal, and analyzing the header by using the header analysis. When detecting the loss of a packet of high importance in the wired section where the data is transmitted, the header analysis processing at the receiving terminal performs the analysis of the packet with high importance. Relay method missing packets is characterized in that it comprises a header analyzing modification step of deleting said first header information and the second header information so as not to be detected. 4. A relay method for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to a receiving terminal via a wireless line, wherein the header at the receiving terminal is Is analyzed, it is detected that the first header information for specifying the sequence number of the packet of high importance and the second header information for specifying the display time of the packet of high importance are inconsistent with each other. A packet retransmission step of retransmitting a packet instructed to be retransmitted in response to a retransmission instruction that is sometimes generated, and analyzing a header of a packet transmitted from the transmitting terminal, and analyzing the header by using the header analysis. When a loss of a packet of high importance is detected in a wired section in which the first header is transmitted, the first header is analyzed by a header analysis process in the receiving terminal. Relaying method characterized by inconsistencies distribution includes a header analysis modifying step of modifying the first header information so as not to be detected. 5. A relay device for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to a receiving terminal via a wireless line, wherein the header at the receiving terminal is Packet retransmitting means for retransmitting a retransmission-instructed packet in response to a retransmission instruction generated when a loss of a packet of high importance is detected by the analyzing process, and a header of a packet transmitted from the transmitting terminal. When the header analysis detects a loss of a packet of high importance in a wired section in which a packet is transmitted by the wired line, the header analysis processing in the receiving terminal performs the header analysis. A relay device comprising: header analysis and correction means for correcting the header so that a high packet loss is not detected. 6. A relay device for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to a receiving terminal via a wireless line, wherein the header at the receiving terminal is The first header information indicating the number of transmitted packets of high importance and the second header information specifying the display time of the packets of high importance are detected by the analysis processing of Packet retransmitting means for retransmitting the retransmitted packet in response to the retransmission instruction generated in step (a), analyzing the header of the packet transmitted from the transmitting terminal, and performing the header analysis, the packet is transmitted by the wired line. When detecting the loss of a packet of high importance in a transmitted wired section, the header analysis processing at the receiving terminal detects inconsistency of the first header information. Relay apparatus characterized by comprising a header analyzing modifying means for modifying the first header information so as not to be. 7. A relay device for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to a receiving terminal via a wireless line, wherein the header at the receiving terminal is Is analyzed, it is detected that the first header information for specifying the sequence number of the packet of high importance and the second header information for specifying the display time of the packet of high importance are inconsistent with each other. Packet retransmitting means for retransmitting a packet instructed to be retransmitted in response to a retransmission instruction that is sometimes generated; analyzing a header of a packet transmitted from the transmitting terminal; When a loss of a packet of high importance is detected in a wired section in which is transmitted, the packet of high importance is detected by a header analysis process in the receiving terminal. Relay device missing bets are characterized by having a header analyzing modification means for deleting said first header information and the second header information so as not to be detected. 8. A relay device for receiving a packet transmitted from a transmitting terminal via a wired line and transmitting the received packet to a receiving terminal via a wireless line, wherein the header at the receiving terminal is Is analyzed, it is detected that the first header information for specifying the sequence number of the packet of high importance and the second header information for specifying the display time of the packet of high importance are inconsistent with each other. Packet retransmitting means for retransmitting a packet instructed to be retransmitted in response to a retransmission instruction that is sometimes generated; analyzing a header of a packet transmitted from the transmitting terminal; When detecting the loss of a packet of high importance in the wired section where the first header information is transmitted, the header analysis processing in the receiving terminal performs the first header information processing. Relay apparatus characterized by inconsistencies and a header analysis modifying means for modifying the first header information so as not to be detected. 9. A packet including first header information indicating the number of transmitted packets of high importance and second header information specifying the display time of the packet of high importance is received and included in the packet. A receiving terminal that performs a decoding process on data and, when both the first header information and the second header information are inconsistent, generates a retransmission request for a packet including the header information. Receiving means for receiving the packet; header analyzing means for analyzing header information contained in the packet received by the receiving means; and decoding means for decoding data contained in the packet received by the receiving means. The header analysis unit analyzes the first header information and the second header information, and includes the header information in a packet including the header information. Receiving terminal, characterized by instructing the decoding scheme that data to the decoding means. 10. The receiving terminal according to claim 9, wherein the header analysis unit is configured to determine when the second header information is inconsistent and the first header information is not inconsistent.
A receiving terminal for instructing the decoding means not to decode data included in a packet including the header information. 11. A packet including first header information for specifying a sequence number of a packet of high importance and second header information for specifying a display time of a packet of high importance is received and included in the packet. A receiving terminal that performs a decoding process on the data to be transmitted and, when both the first header information and the second header information are inconsistent, generates a retransmission request for a packet including the header information. Receiving means for receiving the packet; header analyzing means for analyzing header information contained in the packet received by the receiving means; and decoding for decoding data contained in the packet received by the receiving means. Means for analyzing the first header information and the second header information, and a packet including the header information. Receiving terminal, characterized in that the instruction to said decoding means decoding method of the data contained in the. 12. The receiving terminal according to claim 11, wherein the header analysis unit is configured to determine when the second header information is inconsistent and the first header information is not inconsistent.
A receiving terminal for instructing the decoding means not to decode data included in a packet including the header information.