JP2001320419A - Data transmission system, data transmission, device and data receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transmission system that reduces number of packets discarded at a receiver side due to the occurrence of an error for a wireless transmission block thereby improving the quality of transmission data through a transmission channel in the transmission of packets containing compressed data (transmission information). SOLUTION: The data transmitter of this invention is provided with a packet generating means 12 that generates a non-compression packet Pa that contains transmission information not compressed or a compression packet Pb containing compressed transmission information in response to packet discrimination information, and a transmission means 16 that transmits each packet. The compression packet Pb contains difference information on the basis of transmission information of the recent non-compression packet Pa having been sent before the compression packet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a data transmission method,
Regarding a data transmitting device and a data receiving device, especially when transmitting data in a packet unit between a plurality of information processing devices, a transmitting side compresses data corresponding to a predetermined packet, and a receiving side supports data corresponding to a predetermined packet. The present invention relates to a data transmission process for restoring compressed data to be transmitted.

[0002]

2. Description of the Related Art At present, TCP / I is a typical transmission protocol for transmitting data on the Internet.
P (Transmission Control Protocol / Internet Proto
col) or UDP / IP (User Datagram Protocol / Inte
rnet Protocol) is used. However, when data is transmitted in packet units by using these transmission protocols via a transmission path of a low to medium bit rate (9600 bps to 64 Kbps), the above-mentioned TCP,
A header corresponding to each transmission protocol such as UDP and IP is included, which may cause a communication overhead, that is, a problem that the information amount of the header portion in the packet becomes considerably larger than the information amount of the data portion.

For example, 10-byte data is transferred to a UDP / IP
When transmitting by the protocol, the total size of the UDP / IP packet is 38 bytes, even though the size of the data part of the UDP / IP packet used for transmission by this protocol is 10 bytes. In other words, the total size of the UDP / IP packet is about four times the information amount of the data actually transmitted. If such communication overhead occurs frequently, the effective transmission speed of data on the transmission path is significantly reduced as a result.

At present, as a method of reducing communication overhead by using a plurality of transmission protocols, RF is used.
C (Request For Comments) 1144 and RFC (Re
quest For Comments) V.Jacobson specified in 2508
Is used. Hereinafter, this header compression method will be described. FIG. 28 (a) shows a conventional V. Jacobso
1 shows a data transmission system to which n header compression schemes are applied. In this data transmission system Cs1, a gateway server Sga is connected to the Internet In, and terminal equipment Teq such as a personal computer is connected to the gateway server Sga by a modem, ISDN.
(Integrated Service DigitalNetwork), LAN (Loc
al Area Network). Here, the connection between the terminal device Teq and the gateway server Sga is a point-to-point connection that directly connects the transmission source and the destination by a wired line.
On the transmission path between eq and the gateway server Sga, V.
Packets subjected to data compression processing by the Jacobson header compression method are transmitted by a transmission protocol such as a PPP (Point to Point Protocol) protocol.

In the data transmission system Cs1, when data is transmitted from the gateway server Sga to the terminal device Teq, the gateway server Sga functions as a transmitting device, and the terminal device Teq functions as a receiving device. Fulfill. On the other hand, when data is transmitted from the terminal device Teq to the gateway server Sga,
The gateway server Sga plays the role of the receiving device, and the terminal device Teq plays the role of the transmitting device.

Hereinafter, data transmission using packets in the data transmission system Cs1 will be briefly described. FIG. 28B shows processing required for data transmission in the data transmission system divided into a plurality of layers. FIGS. 29A to 29E show the data structure of a packet generated by the processing of each layer. First, as shown in FIG. 28 (b), in the data transmission system,
A case in which data is transmitted from a server (transmitting device) Sin on the Internet In to a terminal device (receiving device) Teq via a gateway server (relay device) Sga (see data flow Df) will be described.

The data held by the transmitting side device Sin is the first
After the processing of the layer (application layer) Ls1 is performed, the processing of the second layer Ls2 is performed. This allows RT
An RTP packet Prtp corresponding to the P (Realtime Transport Protocol) protocol is generated. The RTP packet Prtp is composed of an RTP header section Hrtp storing header information and an RTP payload (data section) Drtp storing the data. Where RTP
The information in the header portion Hrtp includes a sequence number Isn that is incremented by one each time one packet is transmitted,
It is composed of time information (time stamp) Its used for processing on the data receiving side and other header information Ith (see FIG. 29A). The size of the RTP header part Hrtp is generally 12 bytes, 2 bytes are allocated to the sequence number Isn, and 4 bytes are allocated to the time stamp Its.

Next, the above RTP packet Prtp is subjected to the processing of the third layer Ls3, whereby the UDP (User
A UDP packet Pudp corresponding to the Datagram Protocol) is generated. This UDP packet Pudp is
A UDP header section Hudp storing header information, and R
And a data part Dudp storing the TP packet Prtp (see FIG. 29B).

Subsequently, the UDP packet Pudp includes:
The processing of the fourth hierarchy Ls4 is performed, whereby the IP (Inte
rnet Protocol) IP packet Pi
pa is generated. The IP packet Pipa is composed of an IP header section Hipa storing header information and a data section Dip storing the UDP packet Pudp (see FIG. 29 (c)). Then, the IP packet Pipa
Is a transmission path Cin according to a predetermined transmission standard (for example, Ethernet (registered trademark)) by the processing of the fifth layer Ls5.
Via the gateway server Sga.

Then, in the gateway server Sga, the IP packet Pi from the server Sin on the Internet In is sent.
pa is received in accordance with a predetermined transmission standard (for example, Ethernet) by processing of the lower layer Lin2 corresponding to the processing of the fifth layer Ls5 in the transmitting apparatus. The received IP packet Pipa is separated into its header portion Hipa and data portion Dip by the processing of the upper layer Lin1 corresponding to the processing of the fourth layer Ls4 in the transmitting device. Then, by the processing of the upper layer Leq1 corresponding to the predetermined layer (here, the fourth layer Lr4) in the receiving apparatus, the separated data section Dip includes the header section Hipb including information different from the information of the header section Hipa. As a result, an IP packet Pipb is generated (see FIG. 29D).

[0011] Thereafter, the IP packet Pipb is subjected to the processing of the lower layer Leq2 corresponding to the predetermined layer (here, the fifth layer Lr5) in the receiving apparatus, and the PPP (point-
A PPP packet Pppp corresponding to the to-point protocol is transmitted to the terminal device Teq via the wired line Ceq. This PPP packet Pppp is a CRC for checking the PPP header information Ippp and the received data.
It comprises a header section Hppp storing the code Icrc and a data section Dppp storing the IP packet Pipb (see FIG. 29 (e)). When the PPP packet Pppp is received by the terminal device Teq as a receiving device, the PPP packet Pppp is converted into a header portion Hppp and a data portion Dppp by the processing of the fifth layer Lr5 corresponding to the lower layer Leq2 in the gateway server Sga. Separated.

Next, the IP packet Pipb stored in the PPP data portion Dppp is separated into an IP header portion Hipg and an IP data portion Dip by processing in the fourth layer above the fifth layer Lr5. Subsequently, the UDP packet Pudp stored in the IP data part Dip is stored in the fourth layer Lr4.
Is divided into a UDP header part Hudp and a UDP data part Dudp by the processing of the third hierarchy Lr3, which is higher than the third layer. Further, the RTP packet Prtp stored in the UDP data portion Dudp is processed by the second layer Lr2, which is higher than the third layer Lr3, by the RTP header portion Hrtp and the RTP data portion Drtp.
And separated. Then, the data stored in the RTP payload (RTP data part) Drtp is subjected to the processing of the first layer (application layer) Lr1.

When data is transmitted from the terminal device Teq to the server Sin on the Internet, the terminal device Teq
eq is the transmitting device, and server Sin is the receiving device. In this case, a process completely opposite to the case of transmitting data from the server Sin on the Internet to the terminal device Teq via the gateway server Sga is performed. That is, in each layer Lr2 to Lr5 of the terminal device Teq, a process of generating a packet corresponding to each layer is performed, and in the gateway server Sga, the IP packet Pipb is extracted from the PPP packet Pppp from the terminal device Teq, and The packet is converted into an IP packet Pipa and transmitted to the server Sin on the Internet In based on Ethernet (registered trademark). In the server Sin, the IP packet Pipa is received by the processing of the fifth layer Ls5, and the respective layers Lr2 to Lr2 of the terminal device Teq are received.
Layer Ls4 in the server Sin corresponding to Lr4
Ls2, the data stored in the RTP payload Drtp is extracted, and the data is subjected to the processing of the application layer Ls1.

In the above description, the third hierarchy Ls3
In the processing of Lr3 and Lr3, U
Although the case where the DP packet Pudp is generated is shown, in the processing of the third layer, TCP (Transmission Control
Protocol) may be generated as a TCP packet.

In the data transmission system Cs1 as described above, when data is transmitted by the PPP protocol using the V. Jacobson header compression scheme, as shown in FIG. 30, a PPP packet Pppp transmitted by the protocol is large. Two types of packets are used separately. One is a compressed packet Py (see FIG. 30 (b)) in which data (transmission information) stored in the data part is compressed, and the other is data (transmission information) stored in the data part. ) Are uncompressed uncompressed packets Px (FIG. 3)
0 (a)). FIG. 30 shows in detail a part of the data structure of the PPP packet necessary for explaining the V. Jacobson header compression method.

That is, the uncompressed packet Px is composed of a header section Hpx storing header information and the uncompressed information Ir transmitted by the PPP protocol as transmission information (D).
And a data section Dpx in which is stored. The information of the header section Hpx includes a compression / non-compression identifier Ih1 indicating whether or not the information of the data section Dpx is compressed, and other header information Ih3. In the uncompressed packet Px, the compressed / uncompressed identifier Ih1
Indicates non-compression.

The compressed packet Py is composed of a header section Hpy storing header information and a data section Dpy storing difference information (ΔD) as compression information Id transmitted by the PPP protocol. The header section Hpy
Is composed of a compressed / uncompressed identifier Ih1 indicating whether or not the information of the data portion Dpy is compressed, and other header information Ih3. In the compressed packet Py, the compression / non-compression identifier Ih1 indicates compression. Needless to say, the other header information Ih3 includes the CRC code Icrc shown in FIG.

In the transmission processing of a PPP packet using the V. Jacobson header compression method, an uncompressed packet Px is transmitted from a transmitting side to a receiving side as an initial PPP packet, and a compressed packet Py is transmitted as a subsequent PPP packet. Here, the compressed packet P to be transmitted is
The data portion Dpy of y stores difference information (ΔD) using transmission information corresponding to the PPP packet transmitted immediately before as reference information. The difference information (Δ
D) is, specifically, a difference between the transmission information to be transmitted by the compressed packet to be transmitted and the transmission information as the reference source information.

FIG. 31 is a diagram for conceptually explaining a conventional PPP packet transmission process using the V. Jacobson header compression method. Here, a case where transmission information (D1) to (D4) corresponding to each PPP packet are sequentially transmitted will be described. First, an uncompressed packet Px (1) is transmitted from the transmitting side to the receiving side as the first PPP packet. Data portion Dpx of this uncompressed packet Px (1)
Stores transmission information (D1) as uncompressed information Ir. Thereafter, the compressed packets Py (2) to Py (4) are sequentially transmitted from the transmitting side to the receiving side as PPP packets. These compressed packets Py (2), Py
The data part Dpy of (3), Py (4) contains compression information Id
As difference information (D1-D2), (D2-D3),
(D3-D4) are stored.

Here, the difference information (D1-D2) is
This is difference information between the transmission information (D1) and (D2), and the difference information (D2-D3) is the transmission information (D2) and (D3).
The difference information (D3-D4) is difference information between the transmission information (D3) and (D4). As described above, in each compressed packet, the difference information (ΔD) between the transmission information corresponding to each compressed packet and the transmission information corresponding to the packet transmitted immediately before is stored as the compression information Id. The transmission of such a compressed packet is continued until a transmission error occurs.

On the receiving side, the uncompressed packet Px (1) is received as the first PPP packet.
Compressed packets Py (2) to Py (4) as P packets
Are sequentially received. Then, the uncompressed packet Px (1)
Is processed by the PPP protocol and its data part D
The transmission information (D1) stored in px is extracted.
Also, the compressed packets Py (2), Py (3), Py
(4) is difference information (D1-D2) processed by the PPP protocol and stored in the data part Dpy thereof,
(D2-D3) and (D3-D4) are taken out and V. Jaco
The transmission information D2, D3, D4 corresponding to each compressed packet is restored by the bson header compression method. For example, the restoration of the transmission information (D2) is performed by an addition operation of the difference information (D1-D2) and the transmission information D1, and the other transmission information (D2) is restored.
3) and (D4) are restored in the same manner.

Next, a case where a transmission error occurs in the transmission processing by the PPP protocol using the conventional V. Jacobson compression method will be described. FIG. 32 shows transmission and reception of signals between the transmission side and the reception side when the transmission error occurs. When the receiving side detects a transmission error of a predetermined PPP packet, the receiving side cannot recover the PPP packet received after the occurrence of the error, so that the transmitting side is notified that a recovery error has occurred. For example, as shown in FIG. 32, when the compressed packet Py (2) is not normally transmitted to the receiving side due to a transmission error, the receiving side generates a compressed packet P (2) following the compressed packet Py (2).
Even if y (3) is received, transmission information (D3) which is the original information of the difference information stored in the compressed packet Py (3)
Can not be restored. This is the compressed packet Py
This is because the transmission information (D2) which is the original information of the difference information stored in (2) has not been restored. Therefore, in this case, the receiving side notifies the transmitting side that a restoration error has occurred.

When the transmitting side receives the notification of the occurrence of the restoration error, the uncompressed packet Px (5) is transmitted to the receiving side as a PPP packet immediately after receiving the notification. On the other hand, on the receiving side, all the compressed packets Py (2) to Py (4) received from the time when the transmission error occurs until the time when the uncompressed packet is received thereafter are discarded. By the way, at present, the application of the Internet using a mobile phone, for example, the access of mail to the mobile phone and the service of text information, etc., have been advanced.
Third-generation mobile communication (W-CDMA: Wideband-Code Di)
Infrastructure for next-generation wireless data communication (up to 384 Kbps) is being developed for practical use of vision multiple access.

FIG. 33 (a) is a diagram showing a data transmission system intended for a wireless terminal device supporting W-CDMA. In the data transmission system Cs2, a gateway server Sga is connected to the Internet In, and a portable wireless terminal device (such as a visual terminal) Tmo is connected to the gateway server Sga via a wireless telephone network Cwr such as W-CDMA. It is connected. Also in such a data transmission system Cs2, the portable wireless terminal device T
On the transmission path between mo and the gateway server Sga, V.
Communication of packets that have undergone data compression processing using the Jacobson header compression method is performed using PPP (Point to Point Protocol).
l) etc.

FIG. 33 (b) shows the data transmission system C
The processing required for data transmission in s2 is shown divided into a plurality of layers. In this data transmission system Cs2,
Since the transmission path between the portable wireless terminal device Tmo and the gateway server Sga includes the wireless telephone network Cwr, the data transmission processing between these terminals is performed by connecting the terminal device and the gateway server via a wired line. The above data transmission system Cs1 is different only in the following points. That is, the portable wireless terminal device Tmo is transmitted from the gateway server Sga.
When a PPP packet is transmitted to the gateway server Sga, the PPP obtained by the processing of the second layer Lmo2
The packet is transmitted to the portable wireless terminal device Tmo via the wireless line Cmo by a process corresponding to the W-CDMA system of the third hierarchy Lmo3.

In the portable radio terminal device Tmo, the sixth
By processing corresponding to the W-CDMA system of the layer Lr6, P
A PP packet is received. Thereafter, similarly to the data transmission system Cs1, the fifth to second layers Lr5 to Lr5
The data stored in the RTP payload Drtp is extracted by the processing of r2, and the data is subjected to the processing of the application layer Lr1. The other communication processing in the data transmission system Cs2 shown in FIG. 33B is the same as that in the data transmission system Cs1 shown in FIG. For example, the data transmission system Cs
The processing of the first layer Lmo1 and the second layer Lmo2 on the terminal side in the gateway server Sga in the second embodiment is the same as the processing of the first layer Leq1 and the second layer Leq2 on the terminal side in the gateway server Sga in the data transmission system Cs1. is there.

[0027]

However, while the bit error rate in data transmission in a wired section is 10 ^-5 to 10 ^-7 , the bit error rate in data transmission in a wireless section is about 10 ^-3. PPP using V. Jacobson's header compression method (RFC1144, RFC2508)
In the data transmission process by the protocol, quality degradation of transmission data due to transmission error in a wireless section becomes a problem. In other words, in the data transmission system Cs2 including the wireless section, when data transmission by the PPP protocol is performed using the header compression method of V. Jacobson, the case shown in FIG.
In other words, a case where the receiving side discards the received packet frequently occurs with the occurrence of the transmission error, and as a result, there is a problem that the number of the discarded transmission packets increases dramatically.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. When data transmission by packet is performed by compressing data (transmission information) stored in the packet, an error occurs in a radio section. Thus, a data transmission method, a data transmission device, and a data reception device capable of reducing the number of packets discarded on the receiving side and thereby improving the quality of transmission data on a transmission path including a wireless section are provided. The purpose is to gain.

[0029]

A data transmission method according to the present invention (claim 1) is a data transmission method for sequentially transmitting information from a transmission side to a reception side for each piece of transmission information corresponding to a packet. Transmitting the uncompressed packet in which the transmission information is stored as uncompressed information, and continuously transmitting the compressed packet in which at least a part of the transmission information following the predetermined transmission information is compressed and stored as the compressed information Transmitting side processing, and receiving each packet from the transmitting side, based on the uncompressed information and compressed information stored in each packet, including a receiving side processing to restore the transmission information corresponding to each packet, The transmission-side process compares compressed information to be stored in a compressed packet to be transmitted with transmission information corresponding to a reference packet that is the uncompressed packet, Includes a compression process of creating on the basis of the transmission information corresponding to the elephant packet, the receiving side processing,
It includes a decompression process for decompressing transmission information corresponding to a compressed packet to be decompressed based on transmission information corresponding to the reference packet and compression information included in the decompressed compressed packet.

According to a second aspect of the present invention, in the data transmission method according to the first aspect, in the transmitting process, a packet including a packet identifier indicating the packet together with the uncompressed information is transmitted as the uncompressed packet. Then, as each compressed packet following the uncompressed packet, a packet including a reference packet identifier indicating the uncompressed packet as the reference packet together with the compression information is transmitted. In the compression processing, the reference packet is used as the compression information. And the difference information between the transmission information corresponding to the compressed packet and the transmission information corresponding to the compressed packet.

According to a third aspect of the present invention, in the data transmission method according to the second aspect, in the transmission-side processing, the difference information is calculated in the compressed packet based on transmission information corresponding to the reference packet. In the receiving side processing, difference information in the compressed packet is calculated from transmission information corresponding to the reference packet based on the additional information in the compressed packet.

According to a fourth aspect of the present invention, in the data transmission method according to the third aspect, the additional information is a number of a packet transmitted from the compressed packet after transmission of the uncompressed packet as the reference packet. This is a sequence number that can be used to identify whether there is any.

According to a fifth aspect of the present invention, in the data transmission method according to the third aspect, the additional information is a variable of a calculation formula for calculating difference information in the compressed packet from transmission information corresponding to the reference packet. There is something.

According to a sixth aspect of the present invention, in the data transmission method according to the second aspect, in the transmission-side processing, a plurality of uncompressed packets created so as to be transmitted earlier than the compressed packets are used as reference packets. The compressed packet is associated with the difference information between the transmission information corresponding to each of the reference packets and the transmission information corresponding to the compressed packet, and the reference packet identifier corresponding to each of the reference packets. The difference information and the reference packet identifier
A plurality of sets are stored as the compressed information, and in the receiving-side processing, the transmission information corresponding to the compressed packet is restored by using the difference information and the packet identifier of one of the sets in the compressed packet.

According to a seventh aspect of the present invention, in the data transmission method according to the first aspect, the non-compressed packet is transmitted at a constant period in the transmission-side processing.

According to the present invention (claim 8), in the data transmission method according to claim 1, in the transmitting side processing, when the size of the compressed information included in the compressed packet transmitted to the receiving side exceeds a certain value. , And transmits the uncompressed packet.

According to a ninth aspect of the present invention, in the data transmission method according to the first aspect, in the receiving-side processing, when the size of the compressed information included in the compressed packet from the transmitting side exceeds a certain value, The transmitting side requests the transmitting side to transmit an uncompressed packet, and in the transmitting side processing, when receiving the transmitting request for the uncompressed packet from the receiving side, the transmitting side transmits the uncompressed packet to the receiving side.

According to a tenth aspect of the present invention, in the data transmission method according to the first aspect, in the transmitting side processing, an uncompressed packet storing the same transmission information is continuously transmitted to the receiving side a plurality of times. It is.

According to the present invention (claim 11), in the data transmission method according to claim 10, in the receiving side processing, when a recovery error of the compressed information stored in the compressed packet is detected, the data is recovered to the transmitting side. Notifying that an error has occurred, and changing the number of times the uncompressed packet is continuously transmitted to the receiving side based on the frequency of notification indicating the occurrence of a decompression error from the receiving side in the transmitting side processing. It is.

According to a twelfth aspect of the present invention, in the data transmission method according to the first aspect, the transmitting side processing includes, after transmitting the uncompressed packet, a packet identifier and transmission information stored in the uncompressed packet. The auxiliary transmission packet is transmitted to the receiving side a predetermined number of times.

According to a thirteenth aspect of the present invention, in the data transmission method according to the first aspect, in the transmitting side processing, the uncompressed packet is transmitted to a receiving side with an error correction code added thereto. In the side processing, the uncompressed packet is subjected to an error correction process using an error correction code added thereto.

According to a fourteenth aspect of the present invention, in the data transmission method according to the second aspect, in the transmitting side processing, an error correction code is added to a packet identifier and transmission information in the uncompressed packet. In the processing on the receiving side, the packet identifier and the transmission information included in the uncompressed packet are subjected to an error correction process using an error correction code added thereto.

According to a fifteenth aspect of the present invention, in the data transmission method according to the first aspect, in the processing on the receiving side, when a recovery error of the compression information stored in the compressed packet is detected, the data is recovered to the transmitting side. Notifying that an error has occurred, and transmitting the uncompressed packet by adding an error correction code to the uncompressed packet in accordance with the frequency of notification indicating the occurrence of a decompression error from the receiving side. , One of the processes for transmitting the uncompressed packet without adding an error correction code thereto.

According to a sixteenth aspect of the present invention, in the data transmission method according to the first aspect, in the transmission-side processing, only the uncompressed packet is held in a retransmission buffer as retransmission data. When a transmission error of the uncompressed packet is detected, a request is made to the transmitting side to retransmit an uncompressed packet that is an error packet. In the transmitting side processing, when the retransmission request of the error packet is received, Only when an uncompressed packet corresponding to the error packet is held in the retransmission buffer, the uncompressed packet corresponding to the error packet is retransmitted to the receiving side.

According to a seventeenth aspect of the present invention, in the data transmission method according to the second aspect, in the transmission-side processing, a packet identifier and transmission information stored in the uncompressed packet are used as retransmission data as a retransmission buffer. Hold on to
In the receiving-side process, when a transmission error of the uncompressed packet is detected, a request is made to the transmitting side to retransmit a packet identifier and transmission information stored in the uncompressed packet, which is an error packet. In the side processing, when the request for retransmission of the packet identifier and the transmission information is received, the packet identifier and the transmission information are transmitted only when the packet identifier and the transmission information in the uncompressed packet corresponding to the error packet are held in the retransmission buffer. The information is retransmitted to the receiving side.

The data transmission method according to the present invention (claim 18) is a data transmission method for sequentially transmitting information from a transmission side to a reception side for each piece of transmission information corresponding to a packet. A transmitting-side process of transmitting an uncompressed packet stored as information, and continuously transmitting a compressed packet stored as compressed information in which at least a part of the transmission information following the predetermined transmission information is compressed;
Receiving each packet from the transmitting side and restoring transmission information corresponding to each packet based on the uncompressed information and the compressed information stored in each packet; In the process, compressed information to be stored in a compressed packet to be transmitted is created based on transmission information corresponding to the reference packet, which is the uncompressed packet, and transmission information corresponding to the compressed packet as the transmission target. In the receiving-side process, the transmission information corresponding to the compressed packet to be decompressed is restored based on the transmission information corresponding to the reference packet and the compression information included in the compressed packet to be decompressed. 1 is different from the method of generating the compressed information in the first data transmission process in that the compressed information stored in the compressed packet is different from that in the first data transmission process. And a second data transmission process for reconstructing the compression information stored in the compressed packet by a method different from the compression information restoration method in the first data transmission process on the receiving side. When transmitting the transmission information by packet, the first and second data transmission processes are switched according to the occurrence of a decompression process error for the compressed packet on the receiving side, and the first and second data transmission processes are switched. Of the data transmission process.

According to a nineteenth aspect of the present invention, in the data transmission method according to the eighteenth aspect, the second data transmission process includes, as a transmission-side process, compression information stored in the compressed packet to be transmitted. Includes a transmission process corresponding to the previous packet transmitted immediately before the compressed packet, and a compression process created based on the transmission information corresponding to the compressed packet as the transmission target. This includes a restoration process for restoring the compression information included in the compressed packet using the transmission information corresponding to the previous packet.

According to a twentieth aspect of the present invention, in the data transmission method according to the nineteenth aspect, when an error occurs in a decompression process for decompressing compression information included in a compressed packet on the receiving side, the data is transmitted from the receiving side. Is notified to the receiving side, and if the frequency of notification of the occurrence of the error exceeds a certain value, the transmitting side performs a process on the receiving side to change the restoring process on the receiving side to the restoring process in the first data transmission process. A change notification is performed, and then the transmitting side performs the compression processing in the first data transmission processing. On the other hand, if the frequency of notification of the occurrence of the error becomes equal to or less than a certain value, the transmitting side performs the decompression processing on the receiving side. And a process change notification to the receiving side to change to the decompression process in the second data transmission device. And performs.

According to a twenty-first aspect of the present invention, in the data transmission method according to the nineteenth aspect, on the receiving side, an error occurrence frequency at which an error of a decompression process for decompressing the compression information included in the compressed packet occurs is a predetermined value. Is exceeded, the processing change request is sent to the transmission side to change the compression processing on the transmission side to the compression processing in the first data transmission processing. On the reception side, the error occurrence frequency of the decompression processing is equal to or less than a predetermined value. When it becomes, the processing change request is sent to the transmission side to change the compression processing on the transmission side to the compression processing in the second data transmission processing, and the transmission side performs the compression in the first and second data transmission processing. In the processing, compression processing in data transmission processing in response to a processing change request from the receiving side is performed.

A data transmission method according to the present invention (claim 22) is a data transmission method in which information is sequentially transmitted from a transmitting side to a receiving side for each piece of transmission information corresponding to a packet. A transmitting-side process of transmitting an uncompressed packet stored as information, and continuously transmitting a compressed packet stored as compressed information in which at least a part of the transmission information following the predetermined transmission information is compressed;
Receiving each packet from the transmitting side and restoring transmission information corresponding to each packet based on the uncompressed information and the compressed information stored in each packet; The processing determines compression information to be stored in the compressed packet to be transmitted based on update information related to a packet transmitted earlier than the compressed packet and transmission information corresponding to the compressed packet as the transmission target. And setting information relating to the non-compressed packet as an initial value of the update information, and thereafter, each time a specific compressed packet is created, the update information is associated with the specific compressed packet. And a transmission-side update process for updating the transmission information corresponding to the compressed packet to be decompressed into a packet received earlier than the compressed packet. A restoration process for restoring using the update information related to the packet, setting information related to the uncompressed packet as an initial value of the update information, and then restoring transmission information corresponding to the specific compressed packet Every time
And updating the update information to information related to the specific compressed packet.

According to a twenty-third aspect of the present invention, in the data transmission method according to the twenty-second aspect, the update information includes a reference packet identifier indicating the uncompressed packet or a specific compressed packet as a reference packet, and Corresponding compressed information, wherein the compressed packet is a reference packet identifier indicating the uncompressed packet or the specific compressed packet as a reference packet, and an information update flag indicating whether or not to update the update information. The information update flag in the specific compressed packet is set to a value indicating that the update information should be updated, and the information update flag in a compressed packet other than the specific compressed packet indicates the update information It is set to a value indicating that it should not be updated.

According to a twenty-fourth aspect of the present invention, in the data transmission method according to the twenty-second aspect, in the transmission-side processing, the specific compressed packet is transmitted to the receiving side every time a predetermined time elapses.

According to a twenty-fifth aspect of the present invention, in the data transmission method according to the twenty-second aspect, in the transmitting side processing, the specific compressed packet is transmitted to the receiving side every time a fixed number of compressed packets are transmitted. Things.

According to a twenty-sixth aspect of the present invention, in the data transmission method according to the twenty-second aspect, in the transmission-side processing, when transmission of the specific compressed packet is requested from a receiving side, the specific compressed packet is transmitted. It is sent to the receiving side.

According to a twenty-seventh aspect of the present invention, in the data transmission method according to the twenty-second aspect, in the transmitting-side processing, when the size of the compressed information included in the compressed packet transmitted to the receiving side exceeds a certain value. , And transmits the specific compressed packet.

According to a twenty-second aspect of the present invention, in the data transmission method according to the twenty-second aspect, in the transmitting-side processing, the average value of the size of the compressed information included in the compressed packet transmitted to the receiving side is a fixed value. When it exceeds, the specific compressed packet is transmitted.

According to a twenty-second aspect of the present invention, in the data transmission method according to the twenty-second aspect, the transmission information includes item-specific transmission information corresponding to a plurality of items, and the compression information corresponds to a plurality of items. The item-specific compression information corresponding to each item in the compression information included in the compressed packet includes the item-specific compression information corresponding to each item in the transmission information corresponding to the compressed packet. This is information obtained by compressing using the item-specific transmission information corresponding to each item in the transmission information corresponding to the compressed packet or the specific compression packet, and the item-specific compression information specifies the item corresponding to each item. It includes an item type flag.

According to the present invention (claim 30), in the data transmission method according to claim 29, the item-specific compression information comprises:
It includes data length information indicating the data length.

According to a thirty-first aspect of the present invention, in the data transmission method according to the twenty-ninth aspect, the item-specific compression information is created by using a compression method corresponding to each of a plurality of compression methods. And the above-described item-specific compression information includes decompression method specifying information indicating a decompression method corresponding to the compression method for decompressing the item-specific compression information.

A data transmitting apparatus according to the present invention (claim 32) is a data transmitting apparatus for sequentially transmitting information to a receiving side for each piece of transmission information corresponding to a packet. Means for receiving the received transmission information, an uncompressed packet in which the predetermined transmission information is stored as uncompressed information, and at least a part of the transmission information following the predetermined transmission information is compressed so Packet creation means for creating a compressed packet stored as: a reference information management means for accumulating and managing information relating to the uncompressed packet created by the packet creation means as reference information; Transmitting means for transmitting each packet generated in step (1) as a transmission signal to a receiving side. Compression information to be stored in the compressed packet comprising, it is obtained by the transmission information corresponding to the compressed packet, and configured to create, based on the reference information stored in the reference information management unit.

According to the present invention (claim 33), information transmitted from the transmitting side in packet units is received as a transmission signal,
What is claimed is: 1. A data receiving apparatus for sequentially restoring transmission information corresponding to each packet, comprising: an uncompressed packet receiving said transmission signal, wherein predetermined transmission information is stored as uncompressed information;
And packet receiving means for outputting a compressed packet in which at least a part of the transmission information following the predetermined transmission information is compressed and stored as compressed information, receiving the output of the packet receiving means and storing in each of the packets Packet decompression means for performing a decompression process on each of the packets based on the information being output and outputting transmission information corresponding to each packet; Reference information management means for accumulating and managing related information as reference information, and output means for outputting transmission information corresponding to each of the packets from the packet restoration means, wherein the packet restoration means The transmission information corresponding to the compressed information contained in the compressed packet and the reference information stored in the reference information management means It is obtained by a configuration to be restored on the basis of.

[0062] A data transmitting apparatus according to the present invention (claim 34) is a data transmitting apparatus for sequentially transmitting information to a receiving side for each piece of transmission information corresponding to a packet, wherein the receiving apparatus receives the transmission information as an input signal. Means for receiving the received transmission information, an uncompressed packet in which the predetermined transmission information is stored as uncompressed information, and at least a part of the transmission information following the predetermined transmission information is compressed to obtain compressed information. Packet creation means for creating a compressed packet stored as a packet, information management means for managing information relating to an uncompressed packet and a specific compressed packet created by the packet creation means as update information, Transmission means for transmitting the packet created by the means as a transmission signal to the receiving side, the information management means,
The information related to the uncompressed packet is set as an initial value of the update information, and thereafter, every time a specific compressed packet is created, the update information is updated to information related to the specific compressed packet. Then, the packet creating unit is configured to store compressed information to be stored in a compressed packet to be created by the unit, transmission information corresponding to the compressed packet, and update information stored in the reference information managing unit. It is configured to be created on the basis of.

According to the present invention (claim 35), information transmitted from the transmitting side in packet units is received as a transmission signal,
What is claimed is: 1. A data receiving apparatus for sequentially restoring transmission information corresponding to each packet, comprising: an uncompressed packet receiving said transmission signal, wherein predetermined transmission information is stored as uncompressed information;
And packet receiving means for outputting a compressed packet in which at least a part of the transmission information following the predetermined transmission information is compressed and stored as compressed information, receiving the output of the packet receiving means and storing in each of the packets Packet decompression means for performing a decompression process on each of the packets based on the information being output and outputting transmission information corresponding to each of the packets; A reference information management unit that stores and manages information related to a specific compressed packet as reference information; and an output unit that outputs transmission information corresponding to each packet restored by the packet restoration unit. Means for setting information related to the uncompressed packet as an initial value of the update information,
Each time the decompression process is performed on the specific compressed packet, the update information is configured to be updated to information related to the specific compressed packet, and the packet decompression unit transmits transmission information corresponding to the compressed packet, The decoding is performed based on the compression information included in the compressed packet and the reference information stored in the reference information management means.

[0064]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The point of view and the basic principle of the present invention will be described below. The present inventor has conducted intensive studies on a method for improving the quality of transmission data in a network including a wireless transmission path. By using a header compression method that stores difference information obtained using transmission information corresponding to an uncompressed packet transmitted earlier than this compressed packet as compressed transmission information, It was found that the quality of transmitted data can be improved.

In each of the following embodiments, as for data communication, as shown by a data flow Df in FIG. 33, a single communication from a server Sin on the Internet to a portable wireless terminal device (such as a visual terminal) Tmo is performed. Although only one-way transmission will be described, data is simultaneously communicated in both directions by configuring communication devices such as a server and a terminal device for performing data communication to have both functions of a transmission side and a reception side. Data communication processing can be realized. In addition,
In the data communication from the server Sin on the Internet to the portable wireless terminal device Tmo as described above, the gateway server Sga (see FIG. 33 (b)) receives data from the server Sin on the Internet, Is transmitted to the terminal device Tmo, and the portable wireless terminal device Tmo performs a reception process of receiving data from the gateway server Sga. Also, in each embodiment of the present invention, as transmission information including various header information, R corresponding to IP packet Pipb (see FIG. 29 (d)) is used.
A description will be given of a case where a TP / UDP / IP packet is transmitted by a PPP protocol by compressing its header information.
It is not limited to P / UDP / IP packets and PPP protocol.

(Embodiment 1) FIGS. 1 to 11 are diagrams for explaining a data transmission method according to Embodiment 1 of the present invention. The first embodiment has claims 1 to 9 and
18 to 21, 32, 33, 36, and 37.
The data transmission method according to the first embodiment performs data transmission from the transmitting device to the receiving device in packet units,
The transmitting device creates and transmits an uncompressed packet and a compressed packet, and the receiving device receives the packet from the transmitting device and sequentially restores the received packet. Stores the difference information based on the transmission information stored in the uncompressed packet closest to the compressed packet transmitted earlier than the compressed packet as the corresponding transmission information. Here, the difference information stored in the compressed packet as the transmission target should be transmitted by the transmission target compressed packet from the reference source information using the transmission information stored in the uncompressed packet as the reference source information. This is obtained by subtracting the transmission information.

In the following description, the transmission information stored in the uncompressed packet is also referred to as transmission information corresponding to the uncompressed packet, and the transmission information to be transmitted by the compressed packet corresponds to the compression information. Also called transmission information. FIG. 1 is a diagram for explaining a data transmission method according to the first embodiment of the present invention, wherein an uncompressed packet (FIG. 1A) and a compressed packet (FIG. 1B) used in the data transmission method. ) Shows the data structure. Note that FIG. 1 shows in detail the data structure of the PPP packet, which is necessary for explaining the header compression method, as in FIG.

The details will be described below.
Is composed of a header section Hpa storing header information and a data section Dpa storing uncompressed information Ir transmitted by the PPP protocol. The information in the header portion Hpa includes a compression / non-compression identifier Ih1 indicating whether the information in the data portion Dpa is compressed, and a packet identifier (I
D) Ih2a and other header information Ih3. Here, the compression / non-compression identifier Ih1 of the non-compression packet Pa indicates non-compression. The uncompressed information Ir is transmission information (D) transmitted by the uncompressed packet.

On the other hand, the compressed packet Pb is composed of a header section Hpb storing header information and a data section Dpb storing compression information Id transmitted by the PPP protocol. The information in the header portion Hpb includes a compression / non-compression identifier Ih1 indicating whether or not the information in the data portion Dpb is compressed, and an uncompressed packet (reference packet) storing the transmission information used as the reference source information. Reference packet identifier (ID) Ih for identifying
2b and other header information Ih3. Here, the compression / non-compression identifier Ih1 of the compressed packet Pb indicates compression. The compression information Id includes transmission information (reference source information) corresponding to an uncompressed packet (reference packet) closest to the compressed packet transmitted before the compressed packet Pb, and transmission information corresponding to the compressed packet. This is the difference information. The other header information Ih3 includes the CRC code Icrc shown in FIG.
Needless to say, it is included.

FIG. 2 is a block diagram for explaining a data transmission device in a data transmission system for transmitting data according to the data transmission method of the first embodiment. This data transmitting apparatus 101 corresponds to the gateway server Sga in the data transmission system Cs2 shown in FIG. The data transmitting apparatus 101 receives a first transmission signal S1 including transmission information transmitted from the Internet In side to a reception side (portable wireless terminal device Tmo), and outputs the transmission information as a reception signal Src. 11 and a compression / compression method of packetizing transmission information from the receiving means 11 based on a transmission standard such as a PPP protocol and outputting an uncompressed packet Pa or a compressed packet Pb.
Uncompressed packet creating means 12 and packet creating means 1
And a packet transmitting means 16 for transmitting the packet created by the method 2 as a second transmission signal S2 to the receiving side by a method such as W-CDMA.

The data transmitting apparatus 101 receives the restoration error notification signal Ne indicating that a restoration error has occurred, transmitted from the receiving side, and receives the error notification reception signal S
n, and manages the type of the packet created by the packet creation means 12, and based on the managed packet type information and the error notification reception signal Sn, A compression / non-compression determination unit 13 that determines the type of a packet to be created next and outputs a packet determination signal Jp. Here, in the determination means 13, the management of the packet type is performed by recording the uncompressed / compressed identifier Ih1 of the created packet in association with each packet. Also,
In the determination means 13, the type of the packet created first after the start of transmission and the type of the packet created immediately after receiving the error notification reception signal Sn are uncompressed, and the types of the other packets are compressed. , The packet type is determined.

Further, the data transmitting apparatus 101 associates the transmission information (D) stored as the uncompressed information Ir in the uncompressed packet Pa with the packet identifier (ID) Ih2a for identifying the uncompressed packet. It has reference information management means 15 for additionally managing the transmission side reference information Im1. The transmission-side reference information Im1 includes an identifier (ID) having the same value as the packet identifier (ID) Ih2a and reference source information (D) equal to the transmission information (D) corresponding to the uncompressed packet Pa. Have been.
Each time an uncompressed packet is created by the packet creation means 12, the management means 15 receives the transmission-side management information Cm1 from the creation means 12 and transmits the transmission-side reference information Im.
The identifier (ID) and the reference source information (D) recorded as 1 are updated.

Then, in the data transmitting apparatus 101,
One of the uncompressed packet Pa and the compressed packet Pb is created by the compressed / uncompressed packet creating means 12 based on the packet determination signal Jp. When creating the uncompressed packet Pa, the transmission information (D) is stored as uncompressed information Ir in the data portion Dpa, and the packet identifier Ih is stored in the header portion Hpa.
As 2a, a value (ID) specifying the uncompressed packet Pa
Is stored. When the compressed packet Pb is created, difference information (ΔD) based on the transmission information (D) corresponding to the uncompressed packet as the reference packet is stored in the data portion Dpb as the compressed information Id. In the header portion Hpb, a value (ID) for specifying the uncompressed packet Pa as the reference packet is stored as the reference packet identifier Ih2b. Here, the difference information (ΔD) corresponding to each compressed packet Pb is difference information between transmission information corresponding to the compressed packet and transmission information corresponding to an uncompressed packet as a reference packet. An uncompressed packet as a reference packet is a compressed packet P
b is the last uncompressed packet among the previously created uncompressed packets.

FIG. 3 is a block diagram for explaining a data receiving apparatus in a data transmission system for performing data transmission according to the data transmission method of the first embodiment. This data receiving device 201 corresponds to the portable wireless terminal device Tmo in the data transmission system Cs2 shown in FIG. The data receiving apparatus 201 converts the packet transmitted from the transmitting side as the second transmission signal S2 into W
Packet receiving means 21 for receiving by a method such as CDMA, and a received packet Rp output from the receiving means 21
, An error packet in which an error occurs during transmission is detected, and a normally transmitted reception packet Rp
Is output as a normal packet Pno. Also, the data receiving device 2
01 is a packet restoring unit 23 that receives a normal packet Pno from the detecting unit 22, performs restoration processing on the packet Pno and outputs restoration information Irs, and outputs an error occurrence signal Se when a restoration error occurs.
An error occurrence notification transmitting means 24 for receiving the error occurrence signal Se and transmitting a restoration error notification signal Ne notifying the transmission side that a restoration error has occurred, and the restoration information Irs
And output means 26 for outputting the transmission information (D) as the output signal S3.

Here, in the packet restoring means 23,
As a decompression process for the uncompressed packet, the data portion D of the uncompressed packet Pa based on the PPP protocol or the like
A process of extracting the transmission information (D) from pa is performed. Further, as a restoration process for the compressed packet, the data part Dpb of the compressed packet Pb is based on the PPP protocol or the like.
, The difference information Id is extracted from the data, and the transmission information corresponding to the compressed packet is decompressed with reference to the transmission information corresponding to the uncompressed packet as the reference packet.

Also, when the decompression process is performed on the uncompressed packet Pa by the decompression means 23, the data receiving device 201 sets the packet identifier (ID) Ih2a of the uncompressed packet Pa targeted for the decompression process. And transmission information (D) in association with each other, and has reference information management means 25 for managing as reception side reference information Im2. In addition,
The receiving side reference information Im2 includes the packet identifier (I
D) An identifier (ID) having the same value as Ih2a and reference source information (D) equal to the transmission information (D) corresponding to the uncompressed packet Pa. This management means 25
Every time the decompression process is performed on the uncompressed packet by the packet decompression unit 23, the identifier (ID) and the reference source recorded as the reception side reference information Im2 by the reception side management control signal Cm2 from the decompression unit 23. Information (D)
Is updated. Then, in the data receiving apparatus 201, when the decompression process is performed on the compressed packet by the packet decompression unit 23, the reference packet identifier (ID) in the compressed packet and the transmission information (D) corresponding to the reference packet are respectively The identifier (ID) managed by the reference information management unit 25 and the reference source information (D) corresponding to the identifier (ID) are collated. In addition, as a result of the collation, unless the identifiers (ID) and the information (D) match each other, that is, the management unit 25 refers to the reference necessary for the decompression processing of the compressed packet to be decompressed. Packet identifier (I
When one of D) and the transmission information (D) is not stored, an error occurrence signal Se indicating that a restoration error has occurred is output from the packet restoration means 23 to the error occurrence notification transmission means 24.

Next, the function and effect will be described. 4 and 5 are diagrams for explaining the data transmission method according to the first embodiment. FIG. 4 shows a flow of a plurality of packets from a transmitting side to a receiving side in a normal transmission state, and FIG.
The flow of a plurality of packets from the transmission side to the reception side when a transmission error occurs is shown. Here, the transmission information (D1) to (D4) are information corresponding to each packet, which are grouped so as to be transmitted in packet units. In the first embodiment, the transmission information (D1) is not compressed. It is transmitted by an uncompressed packet Pa (1), and the transmission information (D
2) to (D4) are compressed and uncompressed packets Pa
The compressed packets Pb (2) to Pb (4) subsequent to (1) are sequentially transmitted.

On the transmitting side, first, the uncompressed packet P
a (1) is generated, and the uncompressed packet Pa (1) is transmitted to the receiving side. At this time, the uncompressed packet Pa (1)
Of the transmission information (D
1) is stored, and the header portion Hpa stores an identifier Ih indicating non-compression, a packet identifier (ID = 0) Ih2a for identifying this packet, and other header information Ih3.

Next, the compressed packet Pb (2) is generated, and the compressed packet Pb (2) is transmitted to the receiving side. At this time, the data portion Dpb of the compressed packet Pb (2)
Stores difference information (D1-D2) as compression information Id, and its header Hpb includes an identifier Ih indicating compression.
1, reference packet identifier (ID = 0) Ih2b, and other header information Ih3. The difference information (D1-D2) is obtained by subtracting the transmission information (D2) corresponding to the compressed packet Pb (2) from the transmission information (D1) corresponding to the uncompressed packet Pa (1) as the reference packet. Information that can be obtained.

Subsequently, the compressed packet Pb (3) is generated, and the compressed packet Pb (3) is transmitted to the receiving side. At this time, the data portion Dpb of the compressed packet Pb (3)
Stores difference information (D1-D3) as compression information Id, and its header Hpb has an identifier Ih indicating compression.
1b, reference packet identifier (ID = 0) Ih2b, and other header information Ih3. The difference information (D1-D3) is obtained by subtracting the transmission information (D3) corresponding to the compressed packet Pb (3) from the transmission information (D1) corresponding to the uncompressed packet Pa (1) as the reference packet. This is the information that can be obtained.

Further, the compressed packet Pb (4) is generated, and the compressed packet Pb (4) is transmitted to the receiving side. At this time, the data portion Dpb of the compressed packet Pb (4)
Stores difference information (D1-D4) as compression information Id, and its header portion Hpb has an identifier Ih indicating compression.
1, reference packet identifier (ID = 0) Ih2b, and other header information Ih3. The difference information (D1-D4) is obtained by subtracting the transmission information (D4) corresponding to the compressed packet Pb (4) from the transmission information (D1) corresponding to the uncompressed packet Pa (1) as the reference packet. This is the information that can be obtained.

Here, each of the compressed packets Pb (2),
The reference packet identifier (ID = 0) Ih2b stored in the header portion Hpb of Pb (3) and Pb (4) is based on the fact that the reference packet required for the decompression process for each compressed packet is the uncompressed packet Pa This is an identifier indicating (1).

The uncompressed packet Pa (1) sequentially transmitted from the transmitting side as described above and the compressed packet P
In the normal data transmission state, b (2) to Pb (4) are sequentially received by the receiving side, and transmission information (D1) to (D4) corresponding to each packet is restored. That is, on the receiving side, when the uncompressed packet Pa (1) is received, the transmission information (D1) is extracted from the data part Dpa. Subsequently, when the compressed packet Pb (2) is received, the difference information (D1-D2) is extracted from the data part Dpb, and the uncompressed packet Pa specified as the reference packet by the reference packet identifier (ID = 0) Ih2b. With reference to the transmission information (D1) corresponding to (1), the difference information (D1-D
From 2), the transmission information (D2) corresponding to the compressed packet Pb (2) is restored.

Thereafter, the compressed packets Pb (3), (4)
Is received, as in the case of the compressed packet Pb (2), the difference information (D1-D3),
(D1-D4) is taken out and the reference packet identifier (I
D = 0) With reference to the transmission information (D1) corresponding to the uncompressed packet Pa (1) specified as the reference packet by Ih2b, the compressed packet Pb is obtained from the difference information (D1-D3) and (D1-D4). The transmission information (D3) and (D4) corresponding to (3) and (4) are restored.

In the first embodiment, even if a transmission error of the compressed packet Pb (2) occurs as shown in FIG. 5 in a state where the packet is being transmitted as described above, When the compressed packets Pb (3) and (4) subsequent to the packet Pb (2) are received, the transmission information (D3) corresponding to the compressed packets Pb (3) and (4) is transmitted.
The restoration of (D4) is performed normally. That is, in the first embodiment, the difference information (ΔD) stored in the data portion Dpb of each compressed packet Pb is
Is not the difference information between the transmission information corresponding to the compressed packet Pb and the transmission information corresponding to the packet immediately before the compressed packet Pb.
, And the difference information between the transmission information corresponding to the most recent uncompressed packet Pa transmitted before the compressed packet Pb. Therefore, the first embodiment
In this data transmission system, even if a transmission error of a compressed packet occurs, the transmission error does not affect the restoration processing of the next normally received compressed packet. Therefore, when a transmission error of the compressed packet occurs, only the error packet is discarded, and the receiving side does not notify the transmitting side of the restoration error.

When a transmission error of the uncompressed packet Pa (1) occurs during transmission of information by packet, a notification signal Ne indicating the occurrence of a restoration error is received in the same procedure as that shown in FIG. Transmitted from the sender to the sender.
Immediately after the transmission side receives the restoration error notification signal Ne, an uncompressed packet is transmitted from the transmission side, and a compressed packet is sequentially transmitted following the uncompressed packet. At this time, the receiving side discards the error packet and the subsequent compressed packet, that is, the error received after the occurrence of the transmission error until the uncompressed packet is normally received.

Next, the operation of the data transmitting apparatus 101 in the data transmission system will be described. In the data transmitting apparatus 101, as shown in FIG. 4 or FIG. 5, the transmission information (D1) to (D4) are sequentially transmitted to the receiving side by the corresponding uncompressed packet and compressed packet. More specifically, for example, transmission information (D1) to (D4) (see FIG. 4) transmitted from a server Sin on the Internet (see FIG. 33A) by a transmission method such as Ethernet is transmitted to the data transmitting apparatus. When the signal 101 is input as a first transmission signal S1, the receiving means 11 uses the transmission method to transmit the transmission information (D1) to (D4).
Is received. And the received transmission information (D1)
(D4) are sequentially output to the packet creating means 12 as a received signal Src.

The packet creating means 12 creates a packet for transmitting each piece of transmission information to the receiving side based on a transmission protocol such as the PPP protocol. On this occasion,
The compression / non-compression determination means 13 is inquired about the type of the packet to be created. In response to this inquiry
The determination means 13 provides a packet determination signal Jp indicating the packet type to the packet creation means 12. More specifically, the transmission information (D1) is
2 is input to the first packet after the start of communication.
From No. 3, information indicating the creation of an uncompressed packet is output to the packet creation means 12 as the packet determination signal Jp. Then, the creation unit 12 determines creation of an uncompressed packet based on the packet determination signal Jp, and creates an uncompressed packet Pa (1) in which the transmission information (D1) is stored as uncompressed information Ir. .

At this time, the uncompressed packet Pa (1)
The value “uncompressed” is set to the compressed / uncompressed identifier Ih1 of, and the identifier (ID = 0) indicating the uncompressed packet Pa (1) is set to the packet identifier Ih2a.
The uncompressed packet Pa (1)
Is generated, the reference information management unit 15 uses the transmission side management control signal Cm1 from the generation unit 12 to generate the reference packet identifier (I) as the transmission side reference information Im1.
D) and the reference source information (D) are set in the identifier (ID = 0) indicating the uncompressed packet Pa (1) and the transmission information (D1) corresponding to the uncompressed packet Pa (1), respectively. Then, the uncompressed packet Pa (1) is output to the packet transmitting unit 16 and the packet transmitting unit 16
A predetermined wireless communication method (for example, W-CDMA, etc.)
Is transmitted to the receiving side.

Next, when the transmission information (D2) output from the receiving means 11 is input to the packet generating means 12, even if the first packet is generated after the start of communication, the receiving side This is not the case when the first packet is created after receiving the restoration error notification signal from
Is output to the packet creation unit 12 indicating that the compressed packet is created. Then, the creation unit 12 inquires the management unit 15 about the transmission-side reference information Im1. In this case, in the management unit 15, the reference packet identifier (ID) is set to the identifier (ID = 0) and the reference source information (D) is set to the transmission information (D1). Identifier (ID = 0)
The transmission information (D2) corresponding to the uncompressed packet Pa (1) indicated by
Is compressed. Thereby, difference information (D1-D2) between the transmission information (D1) and the transmission information (D2) is generated as the compression information Id stored in the compressed packet.

Subsequently, in the packet creating means 12,
The difference information (D1) is used as the compression information Id of the transmission information (D2).
A compressed packet Pb (2) storing -D2) is generated. The value “compression” is set in the compression / non-compression identifier Ih1 of the compressed packet Pb (2), and the reference packet identifier Ih2b is set as the reference packet necessary for the restoration processing of the compressed packet Pb (2). Compressed packet P
An identifier (ID = 0) indicating a (1) is set. When the creating unit 12 creates the compressed packet Pb (2), the reference information management unit 15 updates the reference packet identifier (ID) and the reference source information (D) as the sender-side reference identification Im1. Not done. Then, the compressed packet Pb (2) is output to the packet transmitting means 16, and the packet transmitting means 16 transmits the compressed packet Pb (2) to the receiving side (portable wireless terminal device) by a predetermined wireless communication method (for example, W-CDMA or the like). . Then, the receiving means 11
When the transmission information (D3) and (D4) output from the communication device (D3) and (D4) are input to the packet creating means 12, the difference information (D2) is input in the same manner as when the transmission information (D2) is input.
1-D3) is stored in the compressed packet Pb (3) and the difference information (D1-D4) is stored in the compressed packet Pb.
(4) is generated.

FIG. 6 shows the packet creation means 12
And the flow of the processing described in FIG. When the transmission information (D) received by the receiving means 11 is input to the packet creating means 12 (step S).
a1) The determination unit 13 is inquired about which packet to create, an uncompressed packet or a compressed packet (Step Sa2). Based on the packet determination signal Jp from the determination unit 13, the type of the packet to be created is determined. A determination is made (step Sa3). As a result, when an uncompressed packet is to be created, an identifier (ID) is assigned to the uncompressed packet as the packet identifier Ih2a, and an uncompressed packet Pa including the packet identifier Ih2a is created (step Sa7). After that, according to an instruction (transmission side management control signal Cm1) from the packet creation means 12,
Sender-side reference information (that is, identifier (ID) and reference source information (D)) managed by reference information management means 15
m1 is updated (step Sa8).

On the other hand, when a compressed packet is to be created, the packet creation means 12 sends the reference information management means 15 the identifier (ID) and the reference source information (ID) as the transmission-side reference information Im1. It is inquired whether D) is managed (step Sa4). Next, based on the transmission-side reference information (identifier (ID) and reference source information (D)) Im1 from the management unit 15, the compressed packet P
The data part Dpb of b is created (step Sa5). Further, an identifier (ID) is used as a reference packet identifier Ih2b.
Is stored in the header portion Hpb together with other header information Ih3, and a compressed packet Pb is created.
6). Then, the created uncompressed packet Pa or compressed packet Pb is sent to the transmitting means 16 (step Sa9). Thereafter, the processing of the creation unit 12 is performed in step S
It returns to the process of a2. The processing of the creating unit 12 is as follows.
The transmission is performed until the transmission of the last transmission information is completed.

Next, the operation of the data receiving apparatus 201 in the data transmission system will be described. In the data receiving apparatus 201, as shown in FIG. 4 or 5, an uncompressed packet and a compressed packet transmitted from the transmitting side are sequentially received, and a restoration process is performed on each packet.

More specifically, for example, in the packet receiving means 21, the uncompressed packet Pa transmitted from the transmitting side is transmitted.
(1), the compressed packets Pb (2) to Pb (4) are received in order, and the received packet Rp is
2 is output. Then, the error packet detecting means 22
Then, an error detection process is performed on each received packet Rp. As a result, when it is confirmed that the received packet Rp has been transmitted correctly, the received packet Rp is output to the packet restoring means 23 as a normal packet Pno. On the other hand, if it is not confirmed that the received packet Rp has been transmitted correctly, the received packet Rp is discarded. Here, CRC (Cyclic Redundancy Check), which is generally widely used, is used for the error detection method, but the error detection method is not limited to this.

When the uncompressed packet Pa (1) is inputted as the normal packet Pno, the decompression means 23 outputs the compressed / uncompressed identifier I included in the header of the normal packet Pno.
Based on h1, it is determined whether the normal packet Pno is a compressed packet or an uncompressed packet. In this case, since the normal packet Pno received by the decompression means 23 is the uncompressed packet Pa (1), the decompression means 23 transmits the transmission information (D) from the data portion Dpa of the uncompressed packet Pa (1).
A restoration process for extracting 1) is performed.

Next, in the management means 25, the receiving side reference information (identifier (I)) managed by the management means 25 in accordance with the instruction (receiving side management control information) Cm2 from the restoring means 23.
D) and reference source information (D)) Im2 are updated. Thus, the identifier (ID) recorded in the management means 25
And reference source information (D) are identifiers (ID = 0), respectively.
And transmission information (D1). After that, in the restoring means 23, the transmission information (D1) which is the restoration information Irs is sent to the output means 26, and the transmission information (D1) is outputted to the output means 2
6 is output.

Next, when the compressed packet Pb (2) is input as the normal packet Pno,
Whether the normal packet Pno is a compressed packet or an uncompressed packet is determined by the compression / non-compression identifier Ih1 included in the header of the normal packet Pno. In this case, since the normal packet Pno is the compressed packet Pb (2), the decompression means 23 instructs the reference information management means 25 to identify (ID = 0) the reference packet identifier Ih2b included in the compressed packet, And this identifier (I
It is inquired whether reference source information (D1) corresponding to (D = 1) is stored in the management means 25.

In this case, the identifier (ID = 0) and the reference source information (D
1) is stored, the restoring means 23 stores the reference source information (D1) stored in the management means 25 and the difference information (D1-D1) stored in the compressed packet Pb (2).
Using D2), the transmission information (D2) corresponding to the compressed packet Pb (2) is restored. Then, the restoration means 2
3, the transmission information (D2) is sent to the output unit 26 as the restoration information Irs of the difference information (D1-D2), and the transmission information (D2) is output by the output unit 26.

Thereafter, when the compressed packets Pb (3) and Pb (4) are input to the packet decompression means 23 as the normal packet Pno, the compressed packet Pb
In the same way as when (2) is input, the difference information (D1
Transmission information (D3) and (4) are generated as restoration information Irs for -D3) and difference information (D1-D4). The transmission information (D3) and (4) are output to the output unit 2
6 and output by the output means 26.

The identifier (ID = 0) stored in the normal packet Pno input as a compressed packet to the decompression means 23 and the reference source information (D1) corresponding thereto.
Is not stored in the management unit 25, the decompression unit 23 discards the normal packet Pno input as a compressed packet, and the decompression unit 23 informs the error occurrence notifying unit 24 of the decompression error. An error occurrence signal Se indicating that the error has occurred is output. In the notifying unit 24, when the error occurrence signal Se is input, the notifying unit 24 notifies the transmitting side of the occurrence of the restoration error by the restoration error notification signal Ne.

FIG. 7 shows the packet restoring means 23.
And the flow of the processing described in FIG. When the normal packet Pno is input from the error packet detecting unit 22 (step Sb1), the packet restoring unit 23 determines whether the normal packet Pno is an uncompressed packet or a compressed packet (step Sb).
2).

When the normal packet Pno is the uncompressed packet Pa, the transmission information (D) is extracted from the data portion Dpa of the uncompressed packet Pa by the decompression process for the uncompressed packet Pa (step Sb6). Then, the instruction of the packet restoring means 23 (the receiving side management control signal Cm
According to 2), the identifier (ID) and the reference source information (D) which are the receiving side reference information Im2 in the reference information management means 25 are obtained.
Is updated (step Sb7). The transmission information (D) extracted from the data portion Dpa of the uncompressed packet Pa
Is sent to the output means 26 (step Sb10). On the other hand, when the normal packet Pno is the compressed packet Pb, the packet decompression unit 23 inquires the reference information management unit 25 whether the identifier (ID) and the reference source information (D) are managed as the reception side reference information Im2 ( Step Sb3).

Next, it is determined whether or not an uncompressed packet as a reference packet necessary for restoring the difference information of the compressed packet has been received (step Sb).
4). This determination is based on the identifier (ID) stored as the reference packet identifier Ih2b in the compressed packet Pb, the transmission information (D) corresponding to the compressed packet Pb, and the identifier (ID) stored in the reference information management means 25. And the corresponding reference source information (D).

When the uncompressed packet Pa as a reference packet corresponding to the compressed packet Pb has been received, the reference information (D) stored in the reference information management means 25 is used to compress the packet. The transmission information (D) corresponding to the packet Pb is restored (Step Sb5). Further, the restored transmission information (D) is sent to the output means 26 (step Sb10). After that, the process of the restoration unit 23 returns to the process of step Sb2.

As a result of the determination in step Sb4,
If an uncompressed packet as a reference packet corresponding to the received compressed packet has not been received, the packet restoration unit 23 discards the received compressed packet Pb, which is a normal packet Pno (step Sb).
8). Then, the error occurrence signal Se is output to the error occurrence notifying means 24 (step Sb9). After that, the process of the restoration unit 23 returns to the process of step Sb2. Such processing of the restoration means 23 is performed until the last packet is received.

As described above, in the data transmission method according to the first embodiment, the transmission information is transmitted by using the uncompressed packet Pa that stores the transmission information without compression and the compressed packet Pb that stores the transmission information by compressing it. When transmitting in packet units, difference information (ΔD) between the transmission information corresponding to the compressed packet Pb and the transmission information corresponding to the most recent uncompressed packet Pa transmitted before the compressed packet is used as the compression information Id. Since the compressed packet is stored in the compressed packet, even if a transmission error of the compressed packet Pb occurs while the uncompressed packet Pa is normally transmitted, the difference between the normally transmitted compressed packet Pb and the error packet after the error packet is obtained. Information (ΔD)
Can be restored using the transmission information of the uncompressed packet Pa. For this reason, the number of compressed packets to be discarded due to occurrence of a transmission error of the compressed packet is greatly reduced. As a result, it is possible to improve the quality of data transmitted in the wireless section. In other words, the effective speed of data transmission can be improved, and the time and cost required to transmit an unrecoverable packet can be significantly reduced. In the first embodiment, the header portion Hpb of the compressed packet Pb has one reference packet identifier (ID) Ih2b, but the header portion Hpb includes a plurality of the reference packet identifiers (ID). It is also possible. However, in this case, it is necessary to continuously transmit a plurality of uncompressed packets.

(Modification 1 of Embodiment 1) FIG.
The compressed packet has two reference packet identifiers (ID)
Shows the data structure of the uncompressed packet Paa used when two are included. In this case, the uncompressed packet P
aa is transmitted twice consecutively. This uncompressed packet Paa
Is composed of a header section Hpaa storing header information and a data section Dpaa storing transmission information (D) as uncompressed information Ir transmitted by the PPP protocol. Here, the information in the header portion Hpaa includes the compressed / uncompressed identifier Ih1 and the packet identifier (ID) I.
h2a and other header information Ih3. The compression / non-compression identifier Ih1 of the uncompressed packet Paa indicates non-compression.

FIG. 8B shows a data structure of a compressed packet Pbb including two reference packet identifiers (identification IDs). The compressed packet Pbb includes a header section Hpbb storing header information and a data section Dpbb storing first and second compressed information Id1 and Id2 transmitted by the PPP protocol. Here, the information in the header section Hpbb is the compressed / uncompressed identifier I
h1, first and second reference packet identifiers (ID1, ID1) for identifying an uncompressed packet as a reference packet
2) Ih2b1, Ih2b2, and other header information Ih
3 is comprised. Compression of this compressed packet Pbb /
The uncompressed identifier Ih1 indicates compression. Here, the second compressed information Id2 is difference information (Δ2D) between the transmission information corresponding to the latest uncompressed packet Paa transmitted before the compressed packet Pbb and the transmission information corresponding to the compressed packet Pbb. It is. Further, the first compression information Id
1 is difference information (Δ1) between transmission information corresponding to the uncompressed packet Paa transmitted immediately before the latest uncompressed packet Paa and transmission information corresponding to the compressed packet Pbb.
D).

In this case, FIG.
(D1) to (D4) are transmitted as follows. FIG. 9 shows a flow of a plurality of packets from the transmission side to the reception side in a normal transmission state. In the first modification of the first embodiment, the transmission information (D1) and (D2) are not compressed and uncompressed packets Paa (1) and Paa (2).
, And the transmission information (D3) and (D4) are compressed and sequentially transmitted by the compressed packets Pb (3) and Pb (4) following the uncompressed packet Paa (2).

On the transmitting side, first, the uncompressed packet P
aa (1) is generated, and the uncompressed packet Paa (1) is transmitted to the receiving side. At this time, the uncompressed packet Paa (1)
The transmission information (D1) is stored as non-compressed information Ir in the data portion Dpaa of the, and the header portion Hpaa has an identifier Ih indicating non-compression, a packet identifier (ID = 0) Ih2a for identifying this packet, and others. Header information I
h3 is stored.

Subsequently, the uncompressed packet Paa (2) is generated, and the uncompressed packet Paa (2) is transmitted to the receiving side. At this time, the transmission information (D2) is stored as uncompressed information Ir in the data part Dpaa of the uncompressed packet Paa (2), and the identifier I indicating uncompressed is stored in the header Hpaa.
h1, a packet identifier (ID =
1) Ih2a and other header information Ih3 are stored.

After that, the compressed packet Pbb (3) is generated, and the compressed packet Pbb (3) is transmitted to the receiving side. At this time, the data portion Dpbb of the compressed packet Pbb (3)
Stores first and second compression information Id1 and Id2 for the transmission information (D3), and the header portion Hpbb includes
An identifier Ih indicating compression, a first reference packet identifier (ID = 0) Ih2b1, and a second reference packet identifier (I
D = 1) Ih2b2 and other header information Ih3 are stored.

Here, the first compressed information Id1 is the transmission information (D1) corresponding to the packet Paa (1) using the uncompressed packet Pa (1) as a reference packet.
From the transmission information (D) corresponding to the compressed packet Pbb (3)
3) is difference information (D1-D3) obtained by subtracting 3). The compression information Id2 is obtained by using the uncompressed packet Paa (2) as a reference packet.
This is difference information (D2-D3) obtained by subtracting the transmission information (D3) corresponding to the compressed packet Pbb (3) from the transmission information (D2) corresponding to aa (2).

Further, the compressed packet Pbb (4) is generated, and the compressed packet Pbb (4) is transmitted to the receiving side. At this time, the data portion Dpbb of the compressed packet Pbb (4)
Stores first and second compression information Id1 and Id2 for the transmission information (D4), and the header Hpbb includes
An identifier Ih indicating compression, a first reference packet identifier (ID = 0) Ih2b1, and a second reference packet identifier (I
D = 1) Ih2b2 and other header information Ih3 are stored.

Here, the first compressed information Id1 is obtained by using the uncompressed packet Paa (1) as a reference source packet and transmitting information (D) corresponding to the packet Paa (1).
This is difference information (D1-D4) obtained by subtracting the transmission information (D4) corresponding to the compressed packet Pb (4) from 1). The second compressed information Id2 corresponds to the compressed packet Pb (4) from the transmission information (D2) corresponding to the packet Paa (2) using the uncompressed packet Paa (2) as a reference packet. It is difference information (D2-D4) obtained by subtracting the transmission information (D4).

The compressed packets Pbb (3), Pbb (3)
The first packet identifier (ID = 0) Ih2b1 stored in the header portion Hpbb of bb (4) indicates that the reference packet is the uncompressed packet Paa (1). The compressed packets Pbb (3), Pbb
The second packet identifier (ID = 1) Ih2b2 stored in the header part Hpbb of (4) indicates that the reference packet is the uncompressed packet Paa (2).

As described above, the uncompressed packets Paa (1) and Paa (2) sequentially transmitted from the transmitting side and the compressed packets Pbb (3) and Pbb (4) subsequent thereto are sequentially transmitted in a normal data transmission state. The transmission information (D1) to (D4) received by the receiving side and corresponding to each packet is restored. That is, on the receiving side, the uncompressed packet Paa (1), Paa
When (2) is received, the transmission information (D1) and (D2) are extracted from the data part Dpaa. Subsequently, when the compressed packet Pbb (3) is received, the second difference information (D2-D3) is extracted from the data part Dpbb, and the second difference information (ID = 1) Ih2b2 is specified by the second reference packet identifier (ID = 1). 2 with reference to the transmission information (D2) corresponding to the uncompressed packet Pa (2) from the difference information (D2-D3).
The transmission information (D3) corresponding to the compressed packet Pbb (3) is restored.

Thereafter, when the compressed packet Pbb (4) is received, the difference information (D2-D4) is extracted from the data part Dpbb and the second reference packet is received, as in the case of the compressed packet Pbb (3). With reference to the transmission information (D2) corresponding to the uncompressed packet Paa (2) specified by the identifier (ID = 1) Ih2b2, the transmission corresponding to the compressed packet Pbb (4) from the difference information (D2-D4). Information (D
4) is restored.

Here, each compressed packet Pbb (3), Pbb
Uncompressed packet P which is a reference packet for bb (4)
Since both aa (1) and Paa (2) are normally received, an uncompressed packet Paa (2) close to each compressed packet
Is used as a reference packet, but when a transmission error occurs in an uncompressed packet Paa (2) close to each compressed packet,
With the previous uncompressed packet Paa (1) as a reference packet, a decompression process is performed on each compressed packet.

As described above, two uncompressed packets Paa are transmitted successively, and the difference information (Δ1
D), (Δ2D), and a packet storing the first and second reference packet identifiers (ID1, ID2) Ih2b1 and Ih2b2 indicating that both of the uncompressed packets are reference packets, thereby transmitting the compressed packet. If at least one of the identifiers (ID1) and (ID2) and the reference source information corresponding to this identifier are stored in the reference information management unit 25, the compressed packet can be restored. . In other words, the number of compressed packets discarded due to transmission errors of uncompressed packets can be reduced.

Further, in the first embodiment, the compression / non-compression determining means 13 in the data transmitting apparatus 101 performs the non-compression immediately after the start of communication and immediately after receiving the decoding error notification signal Ne from the error occurrence notification receiving means 14. After the packet is created, the packet creating unit 12 is controlled so that the compressed packet is created until the decoding error notification signal Ne is received. The configuration is not limited to such a configuration, and the configuration may be such that the packet creation unit 12 is controlled so that uncompressed packets are transmitted periodically. In other words, in this case, in a state where there is no notification of the occurrence of the restoration error from the receiving side, the transmitting side performs compression / non-compression so that one uncompressed packet is transmitted every time a predetermined number of compressed packets are transmitted. The compression determining unit 13 issues an instruction to the packet creating unit 12. For example, if the number of compressed packets predetermined as the transmission interval of uncompressed packets is 3, 1
Transmission of one uncompressed packet and subsequent transmission of three compressed packets are repeated.

The effect of such a configuration will be briefly described. Image information and audio information, and header information such as TCP / IP packets and UDP / IP packets necessary for transmitting them are stored in PPP packets transmitted by the PPP protocol (that is, in FIGS. 1A and 1B). (Packets shown) are stored as transmission information in the data portions Dpa and Dpb. However, usually, the above image information, audio information,
The difference information between two adjacent packets of the header information and the header information is often very small or 0, but the difference information between packets that are far apart tends to be large. For this reason, by transmitting uncompressed packets periodically, the average value of the difference information is reduced while improving the quality of data transmitted wirelessly, that is, the compression efficiency of information in the data part is also improved. be able to.

Further, the compression / non-compression determining means 13 in the data transmitting apparatus 101 according to the first embodiment determines the average size m of the difference information stored in the data part of the compressed packet.
And the packet generation unit 12 may be configured to transmit an uncompressed packet when the size exceeds a certain value x. Here, the average size m of the difference information
Is obtained as an average value of difference information of a plurality of compressed packets transmitted from the last transmission of the uncompressed packet to the current time. Specifically, four compressed packets are transmitted since the last transmission of the uncompressed packet, and the size of the difference information of these four compressed packets is “2”, “4”, “4”, respectively. , "6",
The average size m of the difference information at the present time is 4 = (2 + 4 +
4 + 6) / 4. Also in this case, it is possible to reduce the average value of the difference information, that is, improve the compression efficiency of the information in the data portion while improving the quality of the data transmitted by radio.

The measurement of the average size m of the difference information may be performed by the data receiving device 201. Specifically, on the receiving side, the packet restoring unit 23 measures the average size m of the difference information, and outputs an oversize signal to the error occurrence notifying unit 24 when the average size m exceeds a certain value x. Configuration. The error occurrence notification transmitting means 24 not only transmits the restoration error notification signal Ne to the transmission side when the error occurrence signal Se is received,
Upon receiving the oversize signal, a packet request signal for requesting the transmission side to transmit an uncompressed packet is transmitted. On the transmission side, the error notification unit 14 in the data transmission terminal 101 compresses the error notification reception signal Sn not only when receiving the restoration error notification signal Ne but also when receiving the packet request signal. The output is provided to the non-compression determining means 13.

The transmission of the uncompressed packet is not performed when the average size x of the difference information exceeds the fixed value x, but is transmitted when the size of the difference information exceeds the fixed value m. Alternatively, it may be performed when it is received. For example, when the size of the compression information included in the compressed packet to be transmitted exceeds a certain value, the data transmitting apparatus 101 may transmit an uncompressed packet following the compressed packet to be transmitted. Good.

When the size of the compressed information included in the compressed packet to be subjected to the decompression processing received from the transmitting side exceeds a certain value, the data receiving apparatus 201 requests the transmitting side to transmit the uncompressed packet. And the data transmission device 10
In No. 1, the uncompressed packet may be transmitted to the receiving side immediately after receiving the transmission request of the uncompressed packet from the receiving side.

(Modification 2 of Embodiment 1) Further, in Embodiment 1 described above, the data portion Dpb of the compressed packet Pb includes, as shown in FIG. The difference information (ΔD) from the entire transmission information corresponding to the compressed packet is stored, but information obtained by compressing only a part of the transmission information corresponding to the compressed packet is stored in the data portion Dpb of the compressed packet Pb. It may be stored. In other words, the transmission information is divided into compression target information to be compressed and non-compression target information not to be compressed. And the difference information from the compression target information in the transmission information corresponding to the compressed packet, and the non-compression target information in the transmission information corresponding to the compressed packet.

FIG. 10A shows the data structure of an uncompressed packet Pc used when the transmission information is composed of information to be compressed and information not to be compressed. This uncompressed packet Pc is composed of a header H storing header information.
pc and the uncompressed information I transmitted by the PPP protocol
and a data section Dpc storing r. The information in the header portion Hpc is, like the uncompressed packet Pa shown in FIG. 1A, used to identify a compressed / uncompressed identifier Ih1 indicating whether or not the information in the data portion is compressed, and to identify the uncompressed packet. Packet identifier (ID) Ih2a
And other header information Ih3.
Here, the data part Dpc stores compression target information that is not compressed and non-compression target information Inc.
The non-compressed compression target information includes item-specific non-compression information Ira, Ira corresponding to the first, second, and third compression target items.
rb, Irc. More specifically, the item-specific uncompressed information Ira, Irb, and Irc are information (Da) and (Da) corresponding to the first, second, and third compression target items, respectively, in the transmission information corresponding to the uncompressed packet. Db), (D
c).

FIG. 10B shows the data structure of a compressed packet Pd used when the transmission information is composed of information to be compressed and information not to be compressed. This compressed packet Pd has a header part HPd storing header information.
And a data portion Dpb that stores partially compressed information transmitted by the PPP protocol. The information in the header portion Hpb includes a compressed / uncompressed identifier Ih1 indicating whether or not the information in the data portion is compressed and a reference packet for identifying the reference packet, similarly to the compressed packet Pb shown in FIG. Identifier (ID)
Ih2b and other header information Ih3.

Here, the data part Dpb stores compressed information to be compressed and non-compression information Inc. The compressed information to be compressed is stored in the first, second, and second data. Item-specific compression information Id corresponding to item 3 to be compressed
a, Idb, and Idc. Specifically, the item-specific compression information Ida is the information (D) corresponding to the first compression target item in the transmission information corresponding to the uncompressed packet.
This is difference information (ΔDa) between a) and information (Da) corresponding to the first compression target item in transmission information corresponding to a compressed packet. The item-specific compression information Idb corresponds to information (Db) corresponding to the second compression target item in the transmission information corresponding to the non-compressed packet, and corresponding to the second compression target item in the transmission information corresponding to the compressed packet. This is difference information (ΔDb) from the information (Db) to be executed. The item-specific compression information Idc is information (Dc) corresponding to the third item to be compressed in the transmission information corresponding to the uncompressed packet.
(Dc) in the transmission information corresponding to the compressed packet and the information (Dc) corresponding to the third compression target item.
Dc).

In this case, the reference information management means 15 in the data transmitting apparatus 101 uses the reference packet identifier (ID)
In addition, each compression target item and information (reference-by-item information) corresponding to each compression target item in reference source information (transmission information in a reference packet) are stored in a table. Further, the reference information management unit 25 in the data receiving device 201 is similar to the reference information management unit 15 described above.
The reference packet identifier (ID), the respective compression target items, and the item-by-item reference source information are stored in a table. In such a configuration, since the transmission information is compressed for each individual compression target item, the management means 15 and the management means can be reduced while maintaining the effect of reducing a certain amount of information by information compression. 2
5 can reduce the storage capacity of a memory such as a RAM mounted thereon.

(Third Modification of First Embodiment) Further, the first embodiment and its first modification, or its second modification.
In the data part of the compressed packet, as shown in FIG. 1 (b) or FIG. 10 (b), the transmission information corresponding to the whole or part of the transmission information corresponding to the compressed packet corresponds to the uncompressed packet. The difference information between the whole or a part of the transmission information and the whole or a part of the transmission information corresponding to the compressed packet is stored. The difference information is calculated instead of or together with the difference information. May be stored in the header or data portion of the compressed packet. For example,
In the compressed packet Pb shown in FIG. 1B, instead of this difference information, difference specifying additional information (K) for calculating the difference information can be stored. Further, in the compressed packet Pd shown in FIG. 10B, instead of the difference information which is at least a part of the plurality of item-specific compressed information, the difference specifying addition for calculating the difference information is performed. Information (K) can be stored.

FIG. 11 is a diagram for explaining the data structure of the packet used when the difference specifying additional information (K) is stored in the compressed packet. FIG.
(a) and (b) respectively show the data structures of the uncompressed packet Pe and the compressed packet Pf used in this case. The uncompressed packet Pe is composed of a header portion Hpe storing header information and a data portion Dpe storing transmission information transmitted by the PPP protocol. The uncompressed packet Pc shown in FIG. It has the same configuration as.

The compressed packet Pf has a header portion Hpf storing header information and a data portion Dpf storing partially compressed information transmitted by the PPP protocol.
It is composed of In this header section Hpf, FIG.
In addition to the compressed / uncompressed identifier Ih1, reference packet identifier (ID) Ih2b, and other header information Ih3 in the compressed packet Pd shown in (b), the difference specifying additional information (K) Ih4 is stored. Further, the data part Dpf contains three items of compression information Ida, Idb, Idc and non-compression target information Inc, as in the case of the compressed packet Pd shown in FIG. 10B. Here, the difference specifying additional information (K) is a sequence number indicating the order of the compressed packet that is located from the uncompressed packet referred to in the decompression process.
The difference information (ΔDa) and (ΔDb) as the item-specific compression information Ida and Idb are equal to the difference specifying additional information (K). Therefore, the difference information (ΔD
The data sizes of a) and (ΔDb) are 0 bytes.

Hereinafter, in the case where the difference specifying additional information (K) is stored in a compressed packet, RTP (Real Time
Protocol) will be described as an example of data transmission using a protocol. Specifically, image information or audio information is
According to the RTP protocol specified by FC1889 / 1890, the data is converted into RTP format data, and
Format data is converted to UDP / IP format data according to the UDP protocol and the IP protocol, and RTP / U
A case where data in the DP / IP format is transmitted from the data transmitting terminal 101 to the data receiving terminal 201 will be described.
The data in the RTP / UDP / IP format is shown in FIG.
This corresponds to the IP packet Pipb shown in FIG. 9 (d).

Usually, the header Hrtp of the RTP packet Prtp
The sequence number Isn (see FIG. 29A) included in
Each time one RTP packet is created, its value increases by one. Also, the packet identification ID (IPv4 (Int Int) included in the header Hipb of the IP packet Pipb
The value of the Ethernet protocol version 4) ID) (not shown) also increases by one each time one IP packet is created. When these values are stored as difference information in the compressed packet, if it is known how many positions the compressed packet is counted from the uncompressed packet as the reference packet corresponding to the compressed packet, 0 Can be

In other words, when the sequence number Isn in the header part Hrtp of the RTP packet Prtp is stored in the compressed packet as simple difference information, the information amount of the sequence number Isn always needs to be 1 byte or more.
By using the difference specifying additional information, the size of the difference information corresponding to the sequence number Isn is usually 0 byte.
And the compression efficiency can be increased. For example, when the size of the difference specifying additional information (K) is 1 byte, RT
Sequence number Is in header part Hrtp of P packet
The size of the difference information of n is usually 0 bytes, and the sum of the difference specifying additional information and the difference information is usually 1 byte. In this case, even if the difference specifying additional information (K) is used, the RTP
The information amount of the packet does not change. However, if the transmission information includes a plurality of pieces of compression target information that can be restored using the same calculation method as the above calculation method (that is, the sum of the difference specifying additional information and the difference information), for example, as described above, the RTP packet When there are two types of information such as a sequence number in a header part and an IPv4 ID in a header part of an IP packet, a substantial effect can be obtained by using the difference specifying additional information, and the compression efficiency can be improved. Can be.

Further, using the difference specifying additional information as a variable, the transmission information corresponding to the reference packet (uncompressed packet) used for the decompression processing of the target compressed packet to be processed is obtained by subtracting the difference corresponding to the target compressed packet from the transmission information. A calculation formula for obtaining information may be used. Here, as the above calculation formula, for example, four arithmetic operations (addition, subtraction, integration, division)
And those that define function operations such as sin and cos. Further, the calculation formula using the difference specifying additional information as a variable may be determined in advance on the transmission side and the reception side, or may be dynamically changed during data transmission according to a certain rule. This makes it possible to further improve the compression efficiency of the transmission information stored in the data portion of the PPP packet, and to further improve the quality of wirelessly transmitted data and the effective transmission speed.

(Embodiment 2) FIG. 12 is a block diagram for explaining a data transmission method according to Embodiment 2 of the present invention, and shows a data transmission apparatus in a data transmission system using this data transmission method. ing. It should be noted that the second embodiment is described in claims 1, 2, 10 to 12, 18 to
21, 32, 33, 36, and 37. This data transmitting apparatus 102 has the same configuration as that of the data transmitting apparatus 101 of the first embodiment, and further includes a non-compressed Packet transmission number monitoring means 31
It is provided with. The transmission count monitoring means 31 receives the packet from the compressed / uncompressed packet creation means 12 and repeats the same uncompressed packet Pa a fixed number of times (here, 2
Times), the packet is output to the packet transmitting means 16 continuously, and then the compressed packet Pb following the uncompressed packet Pa is output to the packet transmitting means 16. Other configurations of the data transmitting apparatus 102 are the same as those of the data transmitting apparatus 101 of the first embodiment. Embodiment 2
The data receiving device in the data transmission system of the third embodiment has the same configuration as the data receiving device 201 in the data transmission system of the first embodiment.

Next, the function and effect will be described. In the data transmitting apparatus 102 according to the second embodiment having such a configuration, the number of transmissions of the uncompressed packet is monitored by the transmission number monitoring unit 31, and the uncompressed packet is output from the packet generation unit 12 to the transmission number monitoring unit 31. Then, the same uncompressed packet Pa (1) is sent from the transmission count monitoring unit 31 a predetermined number of times (here, twice) as shown in FIG. 13, for example.
Subsequently, it is output to the packet transmitting means 16. Thereafter, the compressed packets Pb (2), Pb following the uncompressed packets
(3) and Pb (4) are sequentially output to the packet transmitting means 16. Then, the packet transmission unit 16 sequentially transmits the packets supplied from the transmission count monitoring unit 31 by a predetermined wireless transmission method such as W-CDMA. Other operations in data transmitting apparatus 102 are performed in the same manner as data transmitting apparatus 101 of the first embodiment.

In the data receiving apparatus, when two consecutive uncompressed packets Pa (1) are normally received as shown in FIG. 13, the reference information management means 25 sequentially transmits the identifier (ID) and the reference The original information (D) is updated. As a result, the compressed packet Pb follows the uncompressed packet.
When (2), Pb (3), and Pb (4) are received, the identifier (ID =
0) and reference source information (D1).
Further, even if one of the two consecutive uncompressed packets Pa (1) is not transmitted to the receiving side due to a transmission error, the normally transmitted uncompressed packet is transmitted to the packet decompression unit via the error packet detection unit 22. 23. Therefore, in the reference information management unit 25, the identifier (ID) and the reference source information (D), which are the receiving side reference information Im2, are updated to those for the uncompressed packet Pa (1).

As described above, in the second embodiment, in addition to the configuration of the first embodiment, the uncompressed packet Pa is transmitted twice consecutively, and then the compressed packet Pb following the uncompressed packet Pa is transmitted. Therefore, even if a transmission error occurs in one of the plurality of uncompressed packets transmitted, the receiving side can correctly restore the difference information of the subsequent compressed packet. As a result, the number of received packets discarded due to a restoration error on the receiving side is reduced,
The quality of wirelessly transmitted data can be improved.
In the second embodiment, the uncompressed packet is transmitted twice consecutively. However, the number of continuous transmissions of the uncompressed packet may be three or more.

In the second embodiment, the transmission count monitoring means 31 manages the transmission count of the uncompressed packet so that the uncompressed packet itself is transmitted a plurality of times. Reference numeral 31 denotes that after an uncompressed packet is transmitted, an auxiliary packet different from the uncompressed packet, which stores a packet identifier (ID) and transmission information (D) corresponding to the uncompressed packet, is repeated one or more predetermined times. It may be configured to manage the number of packet transmissions so that the packet is transmitted. In this case, the packet creation means 12
After the creation of an uncompressed packet, an auxiliary packet storing a packet identifier (ID) and transmission information (D) corresponding to the uncompressed packet is created. Thereafter, a plurality of compressed packets corresponding to the uncompressed packets (that is, compressed packets storing difference information created using the transmission information of the uncompressed packets) are created. When the uncompressed packet, the auxiliary packet, and each compressed packet are supplied to the transmission count monitoring unit 31 in the order in which they are created, the transmission count monitoring unit 31 transmits the uncompressed packet. It is transmitted a predetermined number of times continuously. Thereafter, each compressed packet is transmitted sequentially.

In such a configuration, the reference packet identifier and the reference source information are transmitted at least twice by one uncompressed packet and a predetermined number of auxiliary packets before the compressed packet corresponding to the uncompressed packet is transmitted. Therefore, even if a transmission error occurs in one of the uncompressed packet and the auxiliary packet, the receiving side can correctly restore the differential information of the subsequent compressed packet. As a result, the number of received packets discarded due to a restoration error on the receiving side is reduced, and the quality of wirelessly transmitted data can be improved.

Further, in the second embodiment, the uncompressed packet or the auxiliary packet is transmitted continuously for a predetermined number of times. May be changed in accordance with the frequency of notification of the restoration error performed for the. For example, when changing the number of continuous transmissions of uncompressed packets, the compressed / uncompressed transmission determination unit 13 outputs the error notification reception signal Sn from the error occurrence notification reception unit 14.
Is counted per unit time, the count value is compared with a fixed reference value Y, and a transmission number control signal is output to the transmission number monitoring means 31 according to the comparison result. The transmission count monitoring means 31 increases or decreases the transmission count of the uncompressed packet or the auxiliary packet based on the transmission count control signal. In particular,
When the count value exceeds a certain reference value Y, the number of transmissions of the uncompressed packet or the auxiliary packet increases, and when the count value becomes equal to or less than the reference value Y,
The number of transmissions of uncompressed packets or auxiliary packets is reduced.

In such a configuration, when the quality of the transmission data is relatively stable, the transmission efficiency can be increased by reducing the number of transmissions of the uncompressed packet or the auxiliary packet, and the quality of the transmission data is unstable. In the case of, the number of packets to be discarded on the receiving side due to a decompression error can be reduced by increasing the number of times of transmission of the uncompressed packet or the auxiliary packet.

(Embodiment 3) FIGS. 14 and 15 are diagrams for explaining a data transmission method according to Embodiment 3 of the present invention. The third embodiment is based on Claims 1 and 2.
2,13-15,18-21,32,33,36,37
It corresponds to. FIG. 14 is a block diagram showing a data transmission device in a data transmission system that performs data transmission by this data transmission method. This data transmission device 1
03 receives the uncompressed packet Pa and the compressed packet Pb output from the compressed / uncompressed packet creation means 12 in addition to the configuration of the data transmitting apparatus 101 of the first embodiment, and An error correction code adding means 32 for giving a correction code is provided. The means 32 transmits an ECC-added uncompressed packet Pac to which an error correction code has been added and a compressed packet Pb passed through the means 32. This is supplied to the means 16. And the third embodiment
The other configuration of the data transmitting apparatus 103 is the same as that of the data transmitting apparatus 101 of the first embodiment.

FIG. 15 is a block diagram showing a data receiving apparatus in a data transmission system for performing data transmission according to the data transmission method of the third embodiment. The data receiving device 203 according to the third embodiment includes a packet receiving unit 2 in addition to the configuration of the data receiving device 201 according to the first embodiment.
Out of the received packet Rp output from No. 1 to the non-compressed packet Pac to which the error correction code is added, and outputs the uncompressed packet Pac to which the error correction code is added, and outputs the compressed packet Pb to which the error correction code is not added as it is. An error correction unit 41 is provided, and the packet output from the error correction unit 41 is supplied to the error packet detection unit 22. Other configurations of the data receiving device 203 are the same as those of the data receiving device 201 of the first embodiment.

Next, the function and effect will be described. In the data transmitting apparatus 103 according to the third embodiment having such a configuration, the uncompressed packet created by the packet creating means 12, that is, the packet storing the reference source information used for the decompression process of the compressed packet is an error. Correction code adding means 3
2, the error correcting code adding means 32 adds an error correcting code to the uncompressed packet Pa, and adds the ECC added uncompressed packet Pa to which the error correcting code is added.
c is output to the packet transmitting means 16. The compressed packet Pb created by the packet creating unit 12 is output to the packet transmitting unit 16 without being processed by the error correction code adding unit 32. Data transmission device 10
Other operations in the third embodiment are the same as those of the data transmitting apparatus 101 of the first embodiment. On the other hand, in the data receiving device 203, when the received packet Rp output from the packet receiving unit 21 is input to the error correcting unit 41, the EC of the received packet Rp to which the error correction code is added is added.
The C-added uncompressed packet Pac is subjected to error correction processing and output to the error packet detecting means 22, and the compressed packet Pb to which no error correction code is added is output to the error packet detecting means 22 as it is. Other operations of the data receiving device 203 are the same as those of the data transmitting device 201 of the first embodiment.

As described above, in the third embodiment, the ECC is performed by adding the error correction code to the uncompressed packet Pa on the transmitting side.
The transmission of the additional uncompressed packet Pac is performed.
Since error correction processing is performed on the CC-added uncompressed packet Pac using an error correction code, even if a transmission error occurs, most of the uncompressed packets are rescued by the error correction processing on the receiving side. It is possible to suppress occurrence of a bad received uncompressed packet due to an error. As a result, the number of received packets discarded due to a decompression error of a compressed packet following an uncompressed packet is reduced, and the quality of data transmitted wirelessly can be improved.

In the third embodiment, the error correction code is added to the non-compressed packet itself. (Identifier (ID)
And an error correction code may be added only to a portion including the reference source information (D). In this case, at the receiving end, at least the identifier (I
Error correction processing is performed on D) and reference source information (D).

As a result, the number of received packets discarded due to a decompression error of a compressed packet following an uncompressed packet is reduced, and the quality of data transmitted wirelessly can be improved.

Further, in the third embodiment, an error correction code is always added to an uncompressed packet. However, according to the frequency of notification of a restoration error performed from the receiving side to the transmitting side, It may be determined whether or not to add an error correction code to an uncompressed packet. In this case, the compression / non-compression transmission determination means 13 counts the number of times the error notification reception signal Sn from the error occurrence notification reception means 14 is input per unit time, and compares the count value with a fixed reference value Y. The comparison is performed, and an error correction control signal is output to the creation unit 12 according to the comparison result. The creating unit 12 notifies the error correcting code adding unit 32 of whether or not to add an error correcting code to the uncompressed packet based on the error correction control signal. Specifically, when the count value exceeds a certain reference value Y, the error correction code adding means 32 adds an error correction code to the uncompressed packet and outputs the uncompressed packet from the means 32. When the value falls below the value Y,
The error correction code adding means 32 outputs the uncompressed packet without applying the error correction code to the uncompressed packet.
In such a configuration, when the quality of the transmission data is relatively stable, by transmitting the uncompressed packet as it is, the size of the entire uncompressed packet can be suppressed to increase the effective data transmission speed. When the quality of transmission data is unstable, the number of packets discarded on the receiving side due to a restoration error can be reduced by adding an error correction code to an uncompressed packet.

(Embodiment 4) FIGS. 16 and 17 are block diagrams for explaining a data transmission method according to Embodiment 4 of the present invention. FIG. 16 shows a data transmission system using this transmission method. 1 shows a data transmission device 104. It should be noted that the fourth embodiment has the following features.
2, 16 to 21, 32, 33, 36, and 37.

This data transmitting apparatus 104 receives an uncompressed packet retransmission request notification signal Nr from the receiving side instead of error occurrence notification receiving means 14 in data transmitting apparatus 101 of the first embodiment, and issues Received signal Sr
And a retransmission request notification receiving means 14d for outputting a packet. Is changed.

That is, the compression / non-compression transmission determination means 13d in the data transmission device 104 outputs a packet determination signal Jp indicating the type of the packet created by the packet creation means 12d to the packet creation means 12d. When receiving the retransmission request reception signal Sr, a re-creation command signal Sc is output to the packet generation means 12d so that an uncompressed packet to be re-transmitted is generated again instead of the packet determination signal Jp. .

Further, the packet creating means 12d in the data transmitting apparatus 104 creates one of an uncompressed packet and a compressed packet based on the packet determination signal Jp, and upon receiving the re-creation command signal Sc, the reference managing means 15, the last created uncompressed packet is created again based on the identifier (ID) and the reference source information (D). The retransmission request notification signal Nr, the retransmission request reception signal Sr, and the re-creation command signal Sc include an identifier (ID) for specifying an uncompressed packet to be retransmitted. The other configuration of the data transmitting apparatus 104 according to the fourth embodiment is the same as that of the data transmitting apparatus 101 according to the first embodiment.

FIG. 17 shows a data receiving device 204 in the data transmission system according to the fourth embodiment. The data receiving apparatus 204 according to the fourth embodiment temporarily adds a compressed packet determined as a decompression error packet Pre among received compressed packets in addition to the configuration of the data receiving apparatus 201 according to the first embodiment. The restoration error information Pre is stored on the basis of the reference information of the retransmitted uncompressed packet.
In this configuration, the error occurrence notification transmitting means 24 and the packet decompressing means 23 of the data receiving apparatus 201 are modified so as to perform the decompressing process on the compressed packet determined as follows. That is, in the data receiving device 204, instead of the error occurrence notification transmitting means 24 in the data receiving device 201 of the first embodiment, when a restoration error occurs, the restoration process of the restoration error packet is performed based on the error occurrence signal Sre. A retransmission request transmitting unit 24d for outputting a signal (retransmission request notification signal) Nr for requesting retransmission of an uncompressed packet as a required reference packet to the transmitting side is provided.

The packet restoring means 23d in the data receiving apparatus 204 stores the identifier (ID) and the reference source information (D), which are the receiving side reference information Im2 necessary for the restoration processing of the received compressed packet, in the reference information management. Means 2
5, the received compressed packet is determined to be a decompression error packet, and the error occurrence signal Sre is output to the retransmission request notification transmitting means 24d. The error occurrence signal Sre contains an identifier (ID) for specifying an uncompressed packet to be retransmitted. Then, in the data receiving device 204, a decompression process is performed on the compressed packet determined as the decompression error packet Pre based on the identifier (ID) of the retransmitted uncompressed packet and the transmission information (D). I have. The other configuration of the data receiving apparatus 204 of this embodiment is the same as that of the data receiving apparatus 201 of the first embodiment.

Next, the function and effect will be described. In the data transmission system according to the fourth embodiment having such a configuration, when a restoration error of the compressed packet Pb occurs, the non-compressed packet is retransmitted from the transmitting side by the retransmission request notification signal Nr from the receiving side. That is, on the receiving side, the compressed packet Pb is stored in the reference information management unit 25 by the packet decompression unit 23d, in which the identifier (ID) and the reference source information (D) that are the reception side reference information Im2 necessary for the decompression processing are stored. When the compressed packet Pre is determined to be a decompression error packet Pre because it has not been restored, the compressed packet Pre is output from the packet decompression unit 23d to the decompression information storage unit 42 and is temporarily stored. At this time, an error occurrence signal Sre including the reference packet identifier (ID) of the restoration error packet Pre is output to the retransmission request notifying unit 24d. Then, the retransmission request notification transmitting unit 24d transmits the reference packet identifier (I
A retransmission request notification signal Nr including D) is transmitted to the transmitting side.

In the data transmitting apparatus 104, when the retransmission request notification signal Nr including the reference packet identifier (ID) is received by the receiving means 14d, the retransmitting request received signal Sr is output from the receiving means 14d to the determining means 13d. Then, the determination means 13 outputs a signal (re-creation instruction signal) Sc for instructing the creation of the uncompressed packet specified by the reference packet identifier to the packet creation means 12d. Then, the packet creation unit 12d sends the reference information management unit 1
5, an uncompressed packet necessary for the restoration process of the restoration error packet is created again based on the identifier (ID), which is the transmission-side reference information Im1, and the reference source information (D). The packet is transmitted by the packet transmitting means 1
6 is retransmitted to the receiving side.

On the receiving side, when the retransmitted uncompressed packet is received by the packet receiving means 21, it is supplied to the packet restoring means 23d via the error packet detecting means 22. Then, in the packet restoring means 23d, the identifier (ID) and the transmission information (D) are extracted from the retransmitted uncompressed packet, and based on the extracted identifier (ID) and the transmission information (D), the decompression information storing means is stored. The difference information (ΔD) of the compressed packet stored in 42 is restored. On the other hand, the extracted identifier (ID) and transmission information (D) are supplied to the reference information management unit 25, and the identifier (ID) and the reference source information (D), which are the receiving side reference information Im2, are updated by these information. Is done.

As described above, according to the fourth embodiment, when a decompression error of a compressed packet occurs, the transmitting side responds to the retransmission request notification signal Nr from the receiving side to determine whether or not the decompression of the compressed packet is necessary. Since the compressed packet is retransmitted, the receiving side does not have the receiving side reference information (identifier (ID) and reference source information (D)) necessary for the process of restoring the received compressed packet. Is determined as a decompression error packet, the decompression error packet can be correctly decompressed after the retransmission processing of the uncompressed packet is completed. As a result, the number of received packets discarded due to a compression packet decompression error is reduced, and the quality of wirelessly transmitted data can be improved.

In the fourth embodiment, the reference information management means 15 stores the identifier (I
D) and transmission information (D).
The reference information management means 15 may store the uncompressed packet itself. In this case, when retransmitting the uncompressed packet, the process of creating the uncompressed packet in the packet creating unit 12d can be omitted.

In the fourth embodiment, the non-compressed packet itself is retransmitted in response to a retransmission request from the receiving side. Only a portion including (ID) and transmission information (D) may be stored in a predetermined retransmission packet and retransmitted. Also in this case, the decompression processing for the received compressed packet determined as the decompression error packet becomes possible after the transmission of the retransmission packet.
The number of received packets discarded due to a compressed packet decompression error can be reduced, and the quality of wirelessly transmitted data can be improved.

Further, in the first to fourth embodiments,
In the compressed packet, difference information (first difference information) between the transmission information corresponding to the uncompressed packet and the transmission information corresponding to the compressed packet is stored as the compression information. The compression information to be transmitted is
And the other difference information (second difference information) in accordance with the packet transmission status. Here, as the second difference information, the difference information defined in the document of V. Jacobson described in the related art, that is, the transmission information corresponding to the compressed packet, and the packet created immediately before it Difference information from the corresponding transmission information (see FIG. 31) is given.

Hereinafter, as described above, the data transmission method for switching the compression information stored in the compressed packet between the first difference information and the second difference information according to the packet transmission status will be described. A case where the present invention is applied to the data transmission system according to mode 1 will be briefly described with reference to FIGS. 2 and 3. In this case, the error occurrence notification receiving means 14 in the data receiving apparatus 101 is configured to calculate the reception frequency (z) of the restoration error notification signal Ne per unit time transmitted from the receiving side. Further, the compressed / uncompressed packet creating means 12 receives the signal indicating the reception frequency (z) calculated by the error occurrence notification receiving means 14, and the reception frequency (z) exceeds a certain reference value Y. In this case, the first difference information is created as compression information to be stored in the compressed packet. On the other hand, when the reception frequency (z) becomes smaller than the reference value Y, the second difference information is created as the compression information. Is configured to create the difference information.

The operation in this case will be briefly described.
First, when an error occurs in the restoration processing for restoring the compression information included in the compressed packet on the reception side, the reception side notifies the transmission side of the occurrence of the error. Then, on the sending side,
When the error occurrence frequency exceeds a certain value, a process change notification to the receiving side is made to change the restoring process on the receiving side to the restoring process using the first difference information. Thereafter, on the transmitting side, compression processing using the first difference information is performed. On the other hand, on the transmitting side, when the notification frequency of the occurrence of the error becomes equal to or less than a certain value, a process change notification to the receiving side is made to change the restoring process on the receiving side to the restoring process using the second difference information. Then, on the transmitting side, compression processing using the second difference information is performed.
Then, on the receiving side, a decompression process corresponding to the compression process on the transmitting side is performed. In this case, the compressed packet Pb
May include an identifier indicating whether the compression information is one of the first and second difference information.

In the method of switching the compression information Id stored in the compressed packet Pb between the first difference information and the second difference information, the following effects can be obtained. In other words, usually, the difference between two consecutive packets of information such as the transmission information (image information and audio information) and the header information is often very small or 0, but the difference between distant packets is Tends to be larger. For this reason, by switching and using the first difference information and the second difference information as the compression information, it is possible to improve the quality of data transmitted wirelessly and reduce the average value of the difference information. Can also be improved in the compression efficiency of the information stored in the.

In the method of using the above-mentioned compressed information by switching between the first difference information and the second difference information, the transmitting side uses which of the first and second difference information is used. Is determined, but which of the first and second difference information is used as the compression information may be determined according to a command from the receiving side. In this case, switching between the first difference information and the second difference information may be performed based on, for example, the number of occurrences of transmission errors per unit time. In this case, the number of transmission errors per unit time (transmission error occurrence rate) is obtained by the error packet detecting means 22 of the data receiving apparatus, and the obtained transmission error occurrence rate is transmitted by the error occurrence notifying means 24. To be notified.

Further, the switching between the first difference information and the second difference information may be performed according to the frequency of occurrence of a restoration error on the receiving side. In this case, the restoration error occurrence frequency (z) per unit time is obtained by the packet restoration means 23 on the receiving side, and the restoration error occurrence frequency (z) is obtained.
Is compared with a certain reference value Y, and the result of the comparison is notified to the transmitting side by the error occurrence notifying means 24. One is used as compression information.

The operation in this case will be briefly described.
On the receiving side, when the error occurrence frequency at which the error of the decompression process for decompressing the compression information included in the compressed packet occurs exceeds a predetermined value, the compression process on the transmission side is performed by the first
A processing change request to the transmitting side is made to change to the compression processing using the difference information. On the other hand, on the receiving side, when the error occurrence frequency of the above-mentioned restoration processing becomes equal to or less than a predetermined value, a processing change request to the transmitting side is made to change the compression processing on the transmission side to the compression processing using the second difference information. Will be Then, on the transmission side, compression processing using difference information according to the processing change request from the reception side is performed, and on the reception side also, restoration processing corresponding to the compression processing using the difference information requested to the transmission side Is performed.

(Embodiment 5) FIGS. 18 to 27 illustrate a data transmission method according to a fifth embodiment of the present invention and a data transmission system using this data transmission method. This fifth embodiment is similar to the fifth embodiment.
~ 31,34,35,38 ~ 40. The data transmission system according to the fifth embodiment is a system for transmitting information from a transmitting side to a receiving side in packet units.
On the transmitting side, when creating an uncompressed packet storing transmission information and a compressed packet storing compressed transmission information, the transmission information is converted into transmission information (reference information) corresponding to the uncompressed packet and a specific compressed packet. Compress using
On the receiving side, the compressed transmission information is restored using the reference source information.

FIG. 18 shows an uncompressed packet used in the data transmission system of the fifth embodiment (FIG. 18A).
FIG. 3 is a diagram showing a data structure (format) of a compressed packet (FIG. (B)). The uncompressed packet Pg includes a header portion Hpg storing header information and a data portion Dpg storing uncompressed information Ir transmitted by the PPP protocol.
It is composed of The information of the header part Hpg is the header part Hpa in the uncompressed packet Pa of the first embodiment.
Similarly to the above, it is composed of a compressed / uncompressed identifier Ih1 indicating whether or not the information in the data portion is compressed, a packet identifier (ID) Ih2a for identifying an uncompressed packet, and other header information Ih3. I have. Here, the uncompressed information Ir is transmission information (D) transmitted by the uncompressed packet. The compressed packet Ph is
A header portion Hph storing header information and a data portion D storing compression information Id transmitted by the PPP protocol
It consists of ph. The information of the header part Hph is as follows:
A compression / non-compression identifier Ih1 indicating whether or not the information in the data portion is compressed; a reference packet identifier (ID) Ih2b indicating a reference packet necessary for the restoration processing of the compression information Id; Reference information update flag Ih indicating whether to update the reference source information used at the time of
5 and other header information Ih3.

Here, in a normal compressed packet Ph, the reference information update flag Ih5 is set to a value “Off” indicating that the reference source information is not updated, and in a specific compressed packet Ph, the reference information update flag Ih5 is set to “Off”. Update flag Ih5
Is set to a value “On” indicating that the reference source information is updated. The compression information Id includes transmission information (D) corresponding to an uncompressed packet closest to the compressed packet or a specific compressed packet transmitted before the compressed packet Pb to be transmitted, and the transmission target (D). Difference information (Δ) from the transmission information (D) corresponding to the compressed packet
D). Needless to say, the other header information Ih3 includes the CRC code Icrc shown in FIG.

FIG. 19 is a block diagram showing a data transmission device in the data transmission system according to the fifth embodiment. The data transmitting apparatus 105 receives the first transmission signal S1 including the transmission information (D) and outputs a reception signal Src, similarly to the data transmission apparatus 101 of the first embodiment, Src, and receives the transmission information (D)
Packetized on the basis of the control signal to generate an uncompressed packet Pg or a compressed packet Ph;
And a packet transmitting means 16 for transmitting the packet created by the above as a second transmission signal S2 to the receiving side.

Further, similarly to the data transmission apparatus 101, the data transmission apparatus 105 receives the restoration error notification signal Ne from the receiving side and outputs an error notification reception signal Sn, and The type of the packet created by the packet creating means 12e is managed, and the type of the packet to be created next is determined based on the managed packet type information and the error notification reception signal Sn. The compression / output which outputs the determination signal Jp to the packet creation means 12e as the above control signal
And a non-compression transmission determining means 13. Here, the packet creating means 12e creates one of the uncompressed packet Pg and the compressed packet Ph according to the packet determination signal Jp.

The data transmitting apparatus 105 transmits the compressed / uncompressed identifier I from the packet creating means 12e.
Based on h1 and the reference information update flag Ih5, a reference information update determination unit 17 that manages the transmission history of the compressed packet transmitted to the receiving side and determines whether to update the reference source information when the compressed packet is created is provided. are doing. Here, the reference information update determination means 17 outputs a reference information update signal Jr for instructing updating of reference source information to the packet creation means 12e as the control signal every time a packet is generated n times (for example, three times). Configuration. In the packet creating means 12e, the reference information update signal J is used as the control signal.
When r is input, the value “On” indicating that the reference source information is updated is stored in the header portion Hph of the compressed packet Ph as the reference information update flag Ih5, and a specific compressed packet is created. On the other hand, the reference information update signal J
When r is not input, a value “Off” indicating that reference source information is not updated is stored in the header portion Hph of the compressed packet Ph as a reference information update flag Ih5, and a normal compressed packet is created. .

The data transmitting apparatus 105 transmits the transmission information (D) referred to when creating the compression information corresponding to each compressed packet and the reference packet indicating the reference packet corresponding to the transmission information (D). Reference information management means 15 that associates identifiers (ID) with each other and manages them as transmission-side reference information (reference source information (D) and identifier (ID)) Im1.
e. In the reference information management unit 15e, when an uncompressed packet is created, or when a specific compressed packet including the update determination flag “On” Ih5 is created, the transmission-side management control signal Cm1 from the packet creation unit 12e is used. The reference source information (D) and the identifier (ID), which are the transmission-side reference information Im1, are updated.

FIG. 20 is a block diagram illustrating a data receiving device in the data transmission system according to the fifth embodiment. This data receiving apparatus 205 is similar to that of the first embodiment.
Packet receiving means 21 for receiving a packet transmitted from the transmitting side as the second transmission signal S2 and outputting a received packet Rp, and receiving the received packet Rp and detecting an error packet. By
An error packet detecting unit 22 for outputting a normally transmitted normal packet Pno; a packet restoring unit 23e receiving the normal packet Pno from the detecting unit 22 and restoring the uncompressed information or the compressed information stored in each packet;
Output means 2 for outputting restoration information (transmission information (D)) Irs obtained by the restoration processing as an output signal S3
6.

The data receiving apparatus 205 transmits the transmission information (D) referred to when decompressing the compressed information corresponding to each compressed packet and the reference information for identifying the reference packet corresponding to the transmission information (D). Reference information management means 2 for associating with a packet identifier (ID) and managing as reception-side reference information (reference source information (D) and identifier (ID)) Im2
5e. In this reference information management means 25e,
When the decompression process is performed on the non-compressed packet, or when the decompression process is performed on the specific compressed packet including the update determination flag “On” Ih5, the reception management control signal Cm2 from the packet decompression unit 23e receives the data. The reference source information (D) and the identifier (ID), which are the side reference information Im2, are updated.

In the packet restoration means 23e,
When performing the restoration process on the compressed packet Ph, the reference packet identifier (ID) stored in the compressed packet Ph and the reference source information (D) corresponding to the identifier (ID) are held in the reference information management unit 25e. And an error occurrence signal S indicating that a decompression error has occurred for the compressed packet in accordance with the determination result.
e is output. Further, the data receiving device 205
An error occurrence notification transmission unit 24 receives an error occurrence signal Se indicating occurrence of a restoration error from the packet restoration unit 23e, and notifies the transmission side of the occurrence of the restoration error on the reception side by the restoration error notification signal Ne. .

Next, the function and effect will be described. FIGS. 21 and 22 are diagrams for explaining the data transmission method according to the fifth embodiment. FIG. 21 shows a flow of a plurality of packets from the transmission side to the reception side in a normal transmission state, and FIG. 22 shows a flow of a plurality of packets from the transmission side to the reception side when a transmission error occurs. . Here, the transmission information (D1) to (D11) are information corresponding to each packet, which are collected so as to be transmitted in packet units. In the fifth embodiment, the transmission information (D1) is not compressed. The transmission information (D2) to (D11) is transmitted by the uncompressed packet Pg (1), and the transmission information (D2) to (D11) is compressed and the compressed packets Ph (2) to Ph following the uncompressed packet Pg (1)
(11) are sequentially transmitted.

On the transmitting side, first, the uncompressed packet P
g (1) is generated, and the uncompressed packet Pg (1) is transmitted to the receiving side. At this time, the uncompressed packet Pg
In the data part Dpg of (1), the transmission information (D1) is stored as uncompressed information Ir, and its header HPg has an identifier Ih1 indicating uncompressed, a packet identifier (ID = 0) Ih2a identifying this packet, And other header information Ih
3 is stored. After that, the compressed packets Ph (2) to
Ph (11) are sequentially created and transmitted to the receiving side.

At the time of creating such a compressed packet,
For example, the header part Hph of the compressed packets Ph (2) to Ph (5) includes an identifier Ih indicating compression, a reference packet identifier (ID = 0) Ih2b, and a reference information update flag Ih.
5, and other header information Ih3. Also, the data part D of the compressed packets Ph (2) to Ph (5)
The ph stores difference information (D1-D2), difference information (D1-D3), difference information (D1-D4), and difference information (D1-D5), respectively. However, in the fifth embodiment, since the reference source information is updated every time three packets are transmitted, the compressed packets Ph (2) to P (P) are updated.
h (4), the reference information update flag Ih of the header Hph
The value of “5” indicates that the reference source information is not updated.
f ”. On the other hand, in the compressed packet Ph (5), the value of the reference information update flag Ih5 of the header Hph is:
The value is “On” indicating that the reference source information is updated.
That is, after the transmission of the compressed packet Ph (5), the reference packet identifier is a value indicating the compressed packet Ph (5) (ID
= 1), the reference source information is updated to the transmission information (D5) corresponding to the reference packet Ph (5).

Therefore, 4 following the compressed packet Ph (5)
Header H of one compressed packet Ph (6) to Ph (9)
The ph stores an identifier Ih indicating compression, a reference packet identifier (ID = 1) Ih2b, an update determination flag Ih5, and other header information Ih3. The data portions Dph of the compressed packets Ph (6) to Ph (9) have difference information (D5-D6) and difference information (D5-D, respectively).
7), difference information (D5-D8) and difference information (D5-D
9) is stored. These compressed packets Ph (6)-
In Ph (8), the reference information update flag I of the header Hph
The value of h5 is a value “O” indicating that the reference source information is not updated.
ff ”, while the compressed packet Ph (9)
Then, the value of the reference information update flag Ih5 of the header portion Hph is “On” indicating that the reference source information is updated. That is, after the transmission of the compressed packet Ph (9), the reference packet identifier is set to a value (ID = 2) indicating the compressed packet Ph (9), and the reference source information is set to the reference packet Ph (9).
Has been updated to the transmission information (D9) corresponding to.

Therefore, the header portion H of the compressed packets Ph (10) and Ph (11) following the compressed packet Ph (9)
The ph stores an identifier Ih indicating compression, a reference packet identifier (ID = 2) Ih2b, an update determination flag Ih5, and other header information Ih3. The data portions Dph of the compressed packets Ph (10) and Ph (11) have difference information (D9-D10) and difference information (D
9-D11) is stored. These compressed packets Ph
In (10) and Ph (11), the value of the reference information update flag Ih5 of the header portion Hph is a value “Off” indicating that the reference source information is not updated.

The uncompressed packet Pg (1) sequentially transmitted from the transmitting side as described above and the compressed packet P
In a normal data transmission state, h (2) to Ph (11) are sequentially received by the receiving side, and transmission information (D1) to (D11) corresponding to each packet is restored. That is, on the receiving side, when the uncompressed packet Pg (1) is received, the transmission information (D1), which is the uncompressed information Ir, is transmitted from the data portion Dpg.
Is taken out. Thereafter, the compressed packets Ph (2) to P
When h (11) is received, the difference information of the data portion Dph is restored to the transmission information based on the reference source information. Specifically, the packets Ph (2), Ph (3), Ph
(4), and difference information (D1-D2) of Ph (5),
(D1-D3), (D1-D4), (D1-D5)
Uncompressed packet P specified by identifier (ID = 0)
It is restored with reference to the transmission information (D1) corresponding to g (1).

The packets Ph (6), Ph (7),
Difference information of Ph (8) and Ph (9) (D5-D
6), (D5-D7), (D5-D8) and (D5-D
9) is restored with reference to the transmission information (D5) corresponding to the compressed packet Ph (5) specified by the identifier (ID = 1). Further, the packets Ph (10) and Ph
The difference information (D9-D10) and (D9-D1) of (11)
1) is restored with reference to the transmission information (D9) corresponding to the compressed packet Ph (9) specified by the identifier (ID = 2). Then, in the state where the packet is being transmitted as described above, as shown in FIG. 22, when a transmission error of the compressed packet Ph (10) occurs, when the compressed packet Pb (11) is received, The compressed packet Pb
The restoration of the difference information (D9-D11) stored in (11) is performed in the same manner as when no transmission error of the compressed packet Pb (10) has occurred.

That is, also in the fifth embodiment, as in the first embodiment, when restoring the difference information (ΔD) stored in each compressed packet Ph, the processing target is always used as the reference source information. Instead of using the transmission information corresponding to the packet immediately before the compressed packet to be transmitted, the transmission information corresponding to the uncompressed packet transmitted first or immediately after the occurrence of the decompression error, and transmitted every time a predetermined number of packets are transmitted The transmission information corresponding to the specific compressed packet is used. Therefore, in the fifth embodiment, even when a transmission error of a compressed packet other than a specific compressed packet occurs, the transmission error does not affect the restoration processing of the next normally received compressed packet. In this case, on the receiving side, only the error packet is discarded, and the receiving side does not notify the transmitting side of the restoration error.

If a transmission error of the uncompressed packet Pg (1) or a transmission error of a specific compressed packet occurs during transmission of information by packet, a restoration error is performed in the same procedure as that shown in FIG. A notification of occurrence is transmitted to the sender. Immediately after the transmission side receives the notification of the occurrence of the restoration error, the transmission side transmits an uncompressed packet, and thereafter, a normal compressed packet and a specific compressed packet are repeatedly transmitted. At this time, on the receiving side, the error packet and the subsequent compressed packet are discarded.

Next, the operation of data transmitting apparatus 105 when data transmission is performed as described above will be described. For example, continuous transmission information (D1) to (D11) (see FIGS. 21 and 22) transmitted from the information providing side by a transmission method such as Ethernet is input to the data transmission apparatus 105 as the first transmission signal S1. Then, the transmission information (D
1) to (D11) are received. Then, the received transmission information is sequentially output to the compressed / uncompressed packet creating unit 12e as received information Src.

The packet creating means 12e creates a packet for transmitting each piece of transmission information to the receiving side based on a transmission protocol such as the PPP protocol. At this time, according to the packet determination signal Jp from the compression / non-compression transmission determination means 13 and the reference information update signal Jr from the reference information update determination means 17, the non-compression packet, the normal compression packet, and the specific compression packet are compared. Either is created. The uncompressed packet Pg and the compressed packet Ph created in this way are sequentially output to the packet transmitting means 16,
The packet transmission means 16 transmits the second transmission signal S2 to the receiving side. Specifically, when communication is started and when the error notification reception signal Sn is input from the error occurrence notification reception unit 14 to the determination unit 13,
The packet determination signal Jp instructs creation of an uncompressed packet, and in other cases, the packet determination signal Jp instructs creation of a compressed packet.

When creation of a compressed packet is instructed, the reference information update signal Jr is transmitted to the transmission-side reference information Im1.
When an instruction to update is transmitted, a specific compressed packet is created as a compressed packet. When the reference information update signal Jr does not instruct an update of the transmission side reference information Im1, a normal compressed packet is created as a compressed packet. Here, the compression / non-compression determination means 13 generates a compression / non-compression identifier Ih1 of each created packet and an error notification reception signal Sh.
Based on n, it is determined whether to generate an uncompressed packet or a compressed packet, and a packet determination signal Jp indicating the type of the packet to be generated is output. Specifically, immediately after the communication is started, a packet determination signal Jp indicating that an uncompressed packet should be created is output. When the notification reception signal Sn is input, a packet indicating that a compressed packet should be created. A determination signal Jp is output.

The packet creating means 12e creates an uncompressed packet Pg in the same manner as in the first embodiment. The compressed packet Ph is stored in the reference information management unit 15.
The transmission-side reference information Im1 (specifically, the identifier (ID) and the reference source information (D)) managed in e. At this time, the header part Hph of the normal compressed packet
Stores a reference information update flag Ih5 whose value is set to "Off", together with a compressed / uncompressed identifier Ih1, a reference packet identifier Ih2b, and other header information Ih3. Also, the reference information update flag Ih whose value is set to “On” is included in the header portion Hph of the specific compressed packet.
5 is stored together with the compressed / uncompressed identifier Ih1, the reference packet identifier Ih2b, and other header information Ih3. The data part Dph of these compressed packets stores difference information (ΔD) based on the reference source information managed by the reference information management unit 15e.

When the uncompressed packet Pg or the specific compressed packet Ph is created, the reference information management means 15e sends the transmission-side reference information Im based on the transmission-side update control signal Cm1 from the packet creation means 12e.
The identifier (ID) of m1 and the corresponding reference source information (D) are updated to the reference packet identifier (D) for identifying the packet Pg or Ph and the corresponding transmission information (D).

The reference information update judging means 17 calculates the compressed / uncompressed identifier Ih1 of each created packet and the reference information update flag Ih5 of the compressed packet.
The number of normal compressed packets transmitted after transmission of an uncompressed packet or a specific compressed packet is counted.
When the count value reaches a predetermined value (here, 3), a reference information update signal Jr is output, and the count value is reset. When the count value is smaller than a predetermined value (here, 3), the reference information update signal Jr is not output.

Hereinafter, the processing in the packet creation means 12e will be described with reference to the flow chart shown in FIG. When the transmission information received by the receiving unit 11 is input (step Sc1), the packet creating unit 12e inquires of the determining unit 13 about which of an uncompressed packet and a compressed packet should be created (step Sc1). Sc
2) Based on the packet determination signal Jp from the determination means 13, the type of the packet to be created is determined (Step Sc3). As a result, when an uncompressed packet is to be created, an identifier (ID) for identifying the uncompressed packet is assigned as the packet identifier Ih2a, and the uncompressed packet P including the packet identifier (ID) is assigned.
g is created (step Sc11). Thereafter, an instruction from the packet creation means 12e (the transmission-side management control signal Cm
By 1), the identifier (ID) managed by the reference information management unit 15e as the transmission-side reference information Im1 and the corresponding reference source information (D) are updated (step Sc1).
2).

On the other hand, when a compressed packet is to be created, the packet creating means 12e sends the reference information managing means 15
With respect to the identifier (ID) and the reference source information (D) managed by the management unit 15 as the transmission-side reference information Im1.
Is inquired (step Sc4). Then, the data part Dph of the compressed packet is created based on the identifier (ID) obtained by the inquiry and the reference source information (D) (step Sc5). Thereafter, the packet creating unit 12e inquires of the determining unit 17 whether to update the transmission-side reference information Im1 (Step Sc6),
Based on the reference information update signal Jr from the determination means 17,
It is determined whether to update the transmission-side reference information Im1 (step Sc7). As a result, the transmission-side reference information Im1
Is to be updated, the identifier (ID) and reference source information (D) managed by the reference information management unit 15e are updated by an instruction from the packet creation unit 12e (step Sc8), and the specific compression is performed. The packet Ph is created (Step Sc9).

On the other hand, if the transmission-side reference information Im1 should not be updated, a normal compressed packet is created (step Sc10). Then, each of the above packets is sent to the transmitting means 16 (Step Sc13). Thereafter, the processing of the packet creating means 12e returns to step Sc2. Such processing is performed until the last packet is transmitted.

Next, the operation of the data receiving apparatus 205 when packets are sequentially transmitted as shown in FIGS. 21 and 22 will be described. In the packet receiving means 21, packets Pg (1), Ph (2) to
h (11) are sequentially received, and the error packet detecting means 2
2 is output. When it is confirmed that the received packet has been transmitted correctly, the error packet detecting means 22 outputs the received packet to the packet restoring means 23e as a normal packet Pno. If it is not confirmed that the received packet was transmitted correctly,
The received packet is discarded as an error packet. Here, a CRC (Cyclic Redundancy Check), which is generally widely used, is used for the error detection method, but the error detection method is not limited to this.

In the packet restoring means 23e, the compressed / uncompressed identifier I included in the header of the received normal packet (hereinafter, also referred to as normal received packet) Pno
Based on h1, it is determined whether the normally received packet Pno is a compressed packet or an uncompressed packet. For example,
Normally received packet Pno input to the restoring means 23e
Is an uncompressed packet Pg (1), the decompression means 2
In 3e, a restoration process for extracting the transmission information (D1) from the data portion Dpg of the uncompressed packet Pg (1) is performed.

Next, in the management means 25e, the restoration means 2
The identifier (ID) and the reference source information (D) stored as the receiving side reference information Im2 are updated by the receiving side management control signal Cm2 from 3e. As a result, the identifier (ID) and the reference source information (D) recorded as the receiving-side reference information Im2 in the management unit 25e are changed to the identifier (ID = 0) and the transmission information (D1), respectively. Thereafter, in the restoring means 23e, the transmission information (D1) which is the restored information is output to the output means 26, and the output means 2
6 outputs the transmission information (D1).

On the other hand, when the packet input to the decompression means 23e is, for example, a specific compressed packet Ph (5), the reference information management means 25e is instructed by the reference packet identifier (ID = ID) included in the compressed packet. 0) and whether reference source information (D1) corresponding thereto is accumulated. When the reference packet identifier (ID = 0) and the corresponding reference source information (D1) are stored in the management unit 25e, the restoration unit 23e stores the reference source information (D1) and the difference information (D1-D5). , The transmission information (D5) corresponding to the packet is restored. At this time, if either one of the reference packet identifier (ID = 0) and the corresponding reference source information (D1) is not stored in the management unit 25e, the received compressed packet is discarded as an error packet, An error occurrence signal Se indicating that a restoration error has occurred is output to the error occurrence notifying unit 24. Then, the notifying unit 24 transmits a restoration error notification signal Ne to the transmitting side.

Further, in the restoring means 23e, the reference information update flag Ih5 of the header Hph is checked, and when this indicates that the reception side reference information Im2 is to be updated, the reception side update control signal Cm2 indicates the reference information management signal Cm2. Means 25
e. In the management unit 25e, the stored identifier (ID) and the corresponding reference source information (D) are converted into new information, for example, the reference packet identifier (ID = 1) and the reference source information by the reception side update control signal Cm2. (D5)
Will be updated to Thereafter, the transmission information (D5) restored by the restoration unit 23e is output to the output unit 26, and the transmission information (D5) is output by the output unit 26 as a reception signal S3. When the packet input to the decompression unit 23e is a normal compressed packet, the decompression unit 23e and the reference information management unit 25e operate in the same manner as in the first embodiment except for the process of checking the reference information update flag Ih5. Processing is performed.

Hereinafter, the processing in the packet restoration means 23e will be described with reference to the flow chart shown in FIG. When the normally received packet Pno is input from the error packet detecting unit 22 (step Sd1), the packet restoring unit 23e determines whether the normally received packet is an uncompressed packet or a compressed packet (step Sd).
2). If the normally received packet is an uncompressed packet,
The transmission information (D) is extracted from the data portion Dpg of the uncompressed packet Pg by the restoration process for the uncompressed packet (step Sd12). Then, according to the instruction of the packet restoring unit 23e, the identifier (ID) and the reference source information (D), which are the receiving side reference information Im2, in the reference information management unit 25e are updated to the packet identifier and the transmission information of the uncompressed packet ( Step Sd13). The transmission information extracted from the data part of the uncompressed packet is sent to the output means 26 (step Sd9).

When the normal received packet is a compressed packet, the packet decompression means 23e sends the reference information management means 25e a reference packet identifier (ID) Ih2b stored in the compressed packet and a reference source corresponding to the identifier Ih2b. An inquiry is made as to whether or not the information (D) is recorded (step Sd3).
5e (step Sd).
4).

When the reference packet identifier (ID) Ih2b and the corresponding reference source information (D) are not stored in the reference information management means 25e, the normally received packet is discarded as an error packet (step Sd1).
0), the error occurrence signal Se is the error occurrence notification transmitting means 2
4 (step Sd11). Thereafter, the processing by the packet restoring unit 23e returns to the processing of step Sd2. On the other hand, if the reference packet identifier (ID) Ih2b and the corresponding reference source information (D) are stored in the reference information management means 25e, the difference information of the compressed packet is included in the transmission information based on the reference source information. It is restored (step Sd5).

Next, it is determined whether or not the reference information update flag Ih5 stored in the compressed packet indicates that the reference information is to be updated (step Sd6), indicating that the reference information is to be updated. In this case, the identifier (ID) and the reference source information (D) stored in the reference information management unit 25e as the receiving side reference information Im2 are updated to new information (step Sd8). Thereafter, the transmission information is output to the output means 26 (step Sd9). In addition,
If the result of determination in step Sd6 does not indicate that reference information is to be updated, the transmission information is output to the output unit 26 without updating the receiving-side reference information Im2 (step Sd9). The processing of the packet restoring means 23e is performed in step Sd.
Return to 2. Such processing is performed until the last packet is received.

As described above, in the data transmission method according to the fifth embodiment, the uncompressed packet storing the transmission information without compression and the compressed packet storing the transmission information by compressing the transmission information are used.
When transmitting transmission information in packet units, transmission information corresponding to a compressed packet is compressed using transmission information corresponding to a previously transmitted uncompressed packet or a specific compressed packet as reference source information. In a state where an uncompressed packet and a specific compressed packet are transmitted normally, even if a transmission error of the compressed packet occurs, the difference information of the normally transmitted compressed packet after the error packet is the uncompressed packet or It can be restored using transmission information corresponding to a specific compressed packet. For this reason, the number of compressed packets to be discarded due to occurrence of a transmission error of the compressed packet is greatly reduced. As a result, it is possible to improve the quality of data transmitted in the wireless section. In other words, the effective speed of data transmission can be improved, and the time and cost required for unrecoverable packet transmission can be significantly reduced.

In the fifth embodiment, the timing for updating the reference information on the transmitting side and the receiving side, in other words, one specific compressed packet is transmitted every time a predetermined number (three) of compressed packets are transmitted. Although the transmission side determines in advance, the transmission of the specific compressed packet may be performed every time a fixed time (n seconds) elapses, and the size of the difference information stored in the compressed packet is fixed. It may be performed when the threshold value is exceeded.

The transmission of the specific compressed packet is performed when a request for updating the reference source information is received from the receiving side, or when the size of the difference information or the average value of the difference information exceeds a certain threshold value. May be performed. For example, when the transmission side requests transmission of the specific compressed packet from the reception side, the transmission side transmits the specific compression packet to the reception side. Further, the transmitting side transmits the specific compressed packet when the size of the compressed information included in the compressed packet transmitted to the receiving side exceeds a certain value. Further, in the processing on the transmitting side, the specific compressed packet is transmitted when the average value of the size of the compressed information included in the compressed packet transmitted to the receiving side exceeds a certain value. Further, the method of determining the timing for updating the transmission side and reception side reference information may be a combination of the above methods.

By determining the timing for updating the transmission side and reception side reference information as described above, the following effects can be obtained. Normally, the difference between two contiguous packets of the image information, audio information, and header information is often very small or 0, but the difference between packets that are far apart tends to be large. Therefore, by transmitting uncompressed packets periodically, it is expected to improve the quality of data transmitted wirelessly and reduce the average value of difference information, that is, to improve the compression efficiency of the data part. it can.

(Modification of the Fifth Embodiment) In the fifth embodiment, the compression information stored in the data portion Dph of the compressed packet Ph is, as shown in FIGS. , And the difference information (ΔD) between the entire transmission information corresponding to the uncompressed packet and the entire transmission information corresponding to the uncompressed packet, the compressed information stored in the data portion Dph of the compressed packet Ph is Only a part may be compressed. That is, the transmission information is
Partitioning into compression target information corresponding to multiple items to be compressed and non-compression target information not to be compressed,
In the data portion Dph of the compressed packet Ph, difference information between the compression target information in the transmission information corresponding to the uncompressed packet and the compression target information in the transmission information corresponding to the compressed packet is stored as item-specific compression information. The non-compression target information in the transmission information corresponding to the packet is stored.

FIG. 25A shows the data structure of an uncompressed packet used when transmission information is composed of information to be compressed and information not to be compressed. This uncompressed packet Pi has a header portion Hpi storing header information.
And transmission information (D) transmitted by the PPP protocol
Is stored as uncompressed information Ir. As in the case of the uncompressed packet Pg shown in FIG. 18A, the header portion Hpi has a compressed / uncompressed identifier Ih1 indicating whether or not information in the data portion is compressed, and a packet identifier for identifying the uncompressed packet. (ID) Ih2a
And other header information Ih3.
Here, the non-compression information Ir is the item-specific compression target information Ira, Irb, Ir corresponding to the four items to be compressed.
c, Ird, and compression-inapplicable information Inc not to be compressed
It is composed of Here, as the item-specific compression target information (item-specific uncompressed information) Ira, Irb, Irc, Ird, the item-specific transmission information (Da), (Db), (Dc),
(Dd) is stored.

FIG. 25B shows the data structure of a compressed packet Pj used when the transmission information is composed of information to be compressed and information not to be compressed. The compressed packet Pj is composed of a header Hpj storing header information and P
A part transmitted by the PP protocol is composed of a data part Dpj storing compressed information (ΔD). The header part Hpj includes a compressed / uncompressed identifier Ih1,
A reference packet identifier (ID) Ih2b, a reference information update flag Ih5, a difference information presence / absence flag Ih6, and other header information Ih3 are stored. Here, the difference information presence / absence flag Ih6 is a flag that indicates whether or not the compressed item-specific compression target information whose value is not 0 is included in the compressed packet.

Here, the data part Dpj contains item-specific compression information Ida, Idb, Id corresponding to the four compression target items.
c, Idd, and non-compressed non-compression target information Inc. The compressed information Ida includes item-specific transmission information (Da) in transmission information corresponding to an uncompressed packet;
This is a difference from the item-specific transmission information (Da) in the transmission information corresponding to the compressed packet (item-specific difference information (ΔDa)). The compressed information Idb includes item-specific transmission information (Db) in transmission information corresponding to an uncompressed packet and item-specific transmission information (Db) in transmission information corresponding to a compressed packet.
(Item-specific difference information (ΔDb)). The compressed information Idc is the difference between the item-specific transmission information (Dc) in the transmission information corresponding to the uncompressed packet and the item-specific transmission information (Dc) in the transmission information corresponding to the compressed packet (item-specific difference information (ΔDc)). ). Compression information I
dd is the difference (item-specific difference information (ΔDd)) between the item-specific transmission information (Dd) in the transmission information corresponding to the uncompressed packet and the item-specific transmission information (Dd) in the transmission information corresponding to the compressed packet. .

[0219] In this case, the reference information management means 15e in the data transmitting apparatus 105 transmits the reference packet identifier (I
D), information indicating each compression target item to be compressed, and reference source compression (item-specific reference source information) corresponding to each compression target item are tabulated, and the transmission-side reference information Im1
Is stored. Also, the data receiving device 20
5, the reference information management unit 25e also has a reference packet identifier (ID), like the reference information management unit 15e.
Information indicating each compression target item to be compressed, and reference source compression (item-specific reference source information) corresponding to each compression target item
Are stored in a table and stored as reception-side reference information Im2.

FIG. 25C specifically shows a process of compressing the transmission information D (Y) to create a compressed packet Pj (Y). In this case, the reference information management unit 15e stores the reference packet identifier (ID) as the transmission-side reference information Im1.
= X) and item-specific reference source information (Da (X)), (Db
(X)), (Dc (X)), and (Dd (X)).

Further, difference information (ΔDa), (Δ
Db), (ΔDc), and (ΔDd) are expressed by the following (Equation 1)
As shown in (Equation 4), each item of reference source information (Da (X)), (Db (X)),
(Dc (X)), (Dd (X)) and transmission information (D
(Y)), the corresponding item-specific transmission information (Da
(Y)), (Db (Y)), (Dc (Y)), (Dd
(Y)). ΔDa = Da (X) −Da (Y) = 0 (Equation 1) ΔDb = Db (X) −Db (Y) ≠ 0 (Equation 2) ΔDc = Dc (X) −Dc (Y ) ≠ 0 (Equation 3) ΔDd = Dd (X) −Dd (Y) = 0 (Equation 4)

As described above, although the values of the item-specific difference information (ΔDa) and (ΔDd) are 0, the item-specific difference information (ΔD
Since the values of b) and (ΔDc) are not 0, the difference information presence / absence flag I of the header portion Hj of the compressed packet Pj (Y) is
In h6, a value “On” indicating that the value is not 0 among a plurality of item-by-item difference information is set, and the data portion Dj of the compressed packet Pj (Y) has Only difference information (ΔDb) and (ΔDc) are stored.

FIG. 26 is an enlarged view showing a part of the compressed packet Pj (Y). The item-specific difference information includes a subsequent difference information presence / absence flag and a reference source information type flag as information (format) common to these items. Here, the compression information (the difference information for each item (ΔD
b)) The value of the subsequent difference information presence / absence flag Ico1 in Idb is a value “On” indicating that other item-specific difference information is stored in the data portion Dpj following this item-specific difference information (ΔDb). The reference source information type flag Ico2 in the compression information Idb indicates that the item-specific transmission information (Db) should be referenced when the item-specific difference information Idb is restored. Further, the compression information (the difference information by item (ΔD
d)) The value of the subsequent difference information presence / absence flag Ico1 in Idc is stored in the data portion Dpj in the item-specific difference information (ΔDd).
Is "Off" indicating that there is no compression information following the reference information type flag Ico in the compression information Idc.
2 indicates the item-specific transmission information (D
This indicates that c) should be referred to.

As described above, by including the subsequent difference information presence / absence flag Ico1 and the reference source information type flag Ico2 in each item-specific difference information, only the item-specific difference information having a non-zero information amount is added to the data portion of the compressed packet. It can be included as a component of information. Thereby, individual components in the transmission information (information corresponding to each compression target item)
The transmission information can be compressed every time, and the reference information management means 15e on the transmission side can be maintained while maintaining a certain compression effect.
In addition, the storage area such as the RAM in the reference information management unit 25e on the receiving side can be reduced.

Further, in the item-specific difference information Idc, the common information (subsequent difference information presence / absence flag and reference source information type flag) is set as unique information (format) separately from the difference information length data Iun1 and the compression method type flag. Inu2. Here, the difference information length data Iun1 indicates the data size of the item-by-item difference information Idc.
The compression method type flag Inu2 is the item-specific difference information Idc.
The restoration method for restoring the image is specified from among a plurality of restoration methods. Thus, the item-by-item difference information (Δ
By including the difference information length data Iun1 in Dc), when the item-specific difference information (ΔDc) is small, the size can be reduced, and the compression efficiency can be further increased.

The compression method type flag Iun2 is made up of, for example, 2-bit information. By prescribing a compression method according to the value, the compression efficiency can be further increased. For example, when the value of the compression method type flag Iun2 is “00”, the item-by-item difference information is a difference (ΔDn) from the reference source information, and when the value is “01”, the item-by-item difference information is ( ΔDn / 2), and when the value is “10”, the difference information for each item is (ΔDn /
8), and if the value is “11”, the difference information for each item is (ΔDn / 64).

FIG. 27 is a diagram for explaining specific information stored in the uncompressed packet Pi and the compressed packet Pj. FIG. 27A shows data (data) to be transmitted by the packet. FIG. 27B shows transmission information in an uncompressed packet and difference information in a compressed packet. Here, the case of transmitting RTP data (only a part is described) is taken as an example.

The transmission information is an IP packet (RTP / UDP / IP data) Pipb shown in FIG.
The transmission information includes first to fourth compression target items K1 to K4.
Is included. Information corresponding to the first and second compression target items K1 and K2 (compression target information Ira and Irb shown in FIG. 25A) is a sequence number (SN) and a time stamp (ST) of the RTP packet, respectively. , Information corresponding to the third compression target item K3 (FIG. 25)
The compression target information Irc shown in (a) is the identifier (ID) of the IP packet, and the information corresponding to the fourth compression target item K4 (compression target information Ird shown in FIG. 25A) is the UDP port number (Port No. .). Note that each of the above transmission information (D1) to
The specific information corresponding to each compression target item in (D5) is No. in the table of FIG. 1 to No. As shown in column 5.

When RTP / UDP / IP data is actually transmitted as the transmission information (D1) to (D5),
The transmission information is stored in PPP packets (uncompressed packets and compressed packets) by the PPP protocol, and is transmitted from the data transmitting device 105 to the data receiving device 205. At this time, the data portion D of the uncompressed packet Pi (1)
pi is the compression target information Ir in the transmission information (D1).
a, Irb, Irc, and Ird are stored without being compressed. The header portion Hpi includes a 1-bit compressed / uncompressed identifier Ih1 and a 5-bit packet identifier (ID).
Ih2a and Ih2b are other header information Ih3 (FIG. 27).
(not shown in (b)).

Also, compressed packets Pj (2), Pj
In the data part Dpj of (3), the transmission information (D2),
Item-specific compression target information (item-specific uncompressed information) corresponding to each compression target item in (D3) Ira, Irb, Irc, Ird
Are compressed, and the item-specific compression information Ida, Idb, Idc, Idd
Is stored. Here, the compressed packets Pj (2), Pj
The item-specific compression information Ida corresponding to the sequence number (SN) in (3) is 8-bit difference information “1” and “2”, respectively. Compressed packet Pj
The item-specific compression information Idb corresponding to the time stamp (ST) in (2) and Pj (3) is 16-bit difference information “50” and “100”, respectively. The item-specific compression information Idc corresponding to the identifier (ID) of the IP packet in the compressed packets Pj (2) and Pj (3) is 8-bit difference information “1” and “2”, respectively.
The item-specific compression information Idd corresponding to the UDP port number (Port No.) in the compressed packets Pj (2) and Pj (3) is 0 bit.

Further, the compressed packets Pj (2), Pj
The header portion Hpj of (3) includes a 1-bit compressed / uncompressed identifier Ih1 and a 5-bit reference packet identifier (identification I
D) Ih2b and 1-bit reference information update flag Ih5
In addition, a 1-bit difference information presence flag Ih6 and other header information Ih3 (not shown in FIG. 27B) are stored.

In FIGS. 26 and 27, the reference data type flag Ico2,
Difference information length data Iun1, compression method type flag Iun2
Has been shown in the difference information (ΔDn). However, when the reference source information is updated,
That is, when the uncompressed packet Pi is created or when a specific compressed packet (the value of the reference information update flag Ih5 is “O
When the compressed packet Pj of “n” is created, it may be added to its header part Hpi, Hpj or data part Dpi, Dpj.

In this case, the transmission-side reference information management means 15
e and the reference information management unit 25e on the receiving side are configured to manage the difference information length data Iun1 and the compression method type flag Iun2 for each item of reference source information, so that on the receiving side, these data Iun1 and flag Iun2 On the basis of the,
Decompression processing can be performed on the compressed packet.

Thus, the differential information length data Iun1 and the compression method type flag Iun2 are included in the item-specific difference information (ΔDn) in the compressed packet every time the compressed packet is transmitted.
Need not be included, and the compression efficiency can be further increased.

When the item-by-item reference source information is updated as described above, the reference information type flag Ico2 is added to the header portion or data portion of an uncompressed packet or a specific compressed packet.
The method of adding the difference information length data Iun1 and the compression method type flag Iun2 is particularly effective when the compression method for transmission information is complicated and there are a plurality of them, but the compression method changes at regular intervals. Thus, the effect of increasing the compression efficiency can be expected to be even greater.

In the fifth embodiment, the method of using an uncompressed packet, a specific compressed packet, and a normal compressed packet as a data transmission process for transmitting information for each piece of transmission information corresponding to each packet has been described. However, in the data transmission process, the data transmission method described in Embodiment 5 and another data transmission method may be switched according to the packet transmission status. Here, as the other data transmission method, the data transmission method of the first to fourth embodiments or the data transmission method using the conventional V. Jacobson header compression method (see FIG. 31) can be used.

[0237]

As described above, according to the data transmission method of the present invention (claim 1), when transmitting information in packet units, the transmitting side follows the uncompressed packet containing the uncompressed transmission information. Compressed packets including transmission information compressed by the above-mentioned method are continuously transmitted. At this time, the compressed information to be stored in the compressed packet to be transmitted is transmitted by the transmission information corresponding to the reference packet, which is the uncompressed packet, and Based on the transmission information corresponding to the target packet as a target, the transmission side corresponding to the compressed packet is created on the receiving side by:
Since the restoration is performed based on the compression information included in the compressed packet and the transmission information corresponding to the reference packet, even if a transmission error of the compressed packet occurs in the wireless section, the subsequent compressed packet is It can be restored based on the transmission information corresponding to the uncompressed packet as the reference packet. This makes it possible to reduce the number of packets that are discarded on the receiving side due to the occurrence of an error in a wireless section, thereby improving the quality of transmission data on a transmission path including the wireless section.

According to the present invention (claim 2), claim 1
In the described data transmission method, on the transmitting side, as each compressed packet following the uncompressed packet, a packet including a reference packet identifier indicating the uncompressed packet as the reference packet together with the compression information is transmitted.
On the receiving side, a reference packet required for the decompression process on the compressed packet can be specified by the reference packet identifier. In addition, since difference information between the transmission information corresponding to the reference packet and the transmission information corresponding to the compressed packet is created as the compression information, the compression information included in the compressed packet can be created by a simple calculation process. Can be.

According to the present invention (Claim 3), Claim 2
In the data transmission method described above, on the transmitting side, the compressed packet stores additional information for calculating the difference information based on the transmission information corresponding to the reference packet, and on the receiving side, the compressed packet Is calculated from the transmission information corresponding to the reference packet based on the additional information, so that the information amount of the difference information can be reduced, and the data compression efficiency can be improved. Can also be improved.

According to the present invention (claim 4), claim 3
In the data transmission method described above, as the additional information,
Since the compressed packet uses a sequence number capable of identifying the order of the packet transmitted after the transmission of the uncompressed packet as the reference packet, for transmission information that increases by a certain amount each time a packet is transmitted, The difference information can be set to 0 bits.

According to the present invention (claim 5), claim 3
In the data transmission method described above, as the additional information,
Since a variable of a calculation formula for calculating difference information in the compressed packet from the transmission information corresponding to the reference packet is used, for transmission information that fluctuates according to a certain function each time a packet is transmitted, the difference information is greatly reduced. Can be.

According to the present invention (Claim 6), Claim 2
In the data transmission method described above, the transmitting side uses a plurality of uncompressed packets created to be transmitted earlier than the compressed packet as reference packets, and the compressed packet includes a transmission corresponding to each of the reference packets. The difference information between the information and the transmission information corresponding to the compressed packet is associated with the reference packet identifier corresponding to each of the reference packets, and a plurality of sets of the corresponding difference information and the reference packet identifier are stored as the compression information. , In the receiving side process,
Since the transmission information corresponding to the compressed packet is decompressed using any pair of difference information and the packet identifier in the compressed packet, the reliability of the transmission process for the uncompressed packet including the information necessary for decompression of the compressed packet , And the quality of wirelessly transmitted data can be greatly improved.

According to the present invention (claim 7), claim 1
In the data transmission method described above, in the transmission-side processing,
Since the above-mentioned uncompressed packet is transmitted at a constant period, the data size of the compressed packet is suppressed from becoming extremely large
The compression efficiency of transmission information can be kept within a substantially constant fluctuation range. As a result, not only the quality of wirelessly transmitted data but also the data transmission efficiency can be improved.

According to the present invention (claim 8), claim 1
In the data transmission method described above, the transmitting side transmits the uncompressed packet when the size of the compressed information included in the compressed packet transmitted to the receiving side exceeds a certain value, so that the data size of the compressed packet is reduced. In addition, it is possible to increase the compression efficiency of the transmission information, thereby improving not only the quality of the wireless transmission data but also the data transmission efficiency.

According to the present invention (claim 9), claim 1
In the data transmission method described above, the receiving side requests the transmitting side to transmit an uncompressed packet when the size of the compressed information included in the compressed packet from the transmitting side exceeds a certain value. Since the non-compressed packet is transmitted to the receiving side in response to the transmission request of the uncompressed packet from the side, it is possible to suppress the data size of the compressed packet and increase the compression efficiency of the transmission information, and improve only the quality of the radio transmission data. In addition, data transmission efficiency can be improved.

According to the present invention (claim 10), in the data transmission method according to claim 1, the transmitting side transmits the uncompressed packet storing the same transmission information to the receiving side continuously plural times. In addition, the reliability of transmission processing for uncompressed packets required for restoring compressed packets can be improved, and thereby the quality of wirelessly transmitted data can be greatly improved.

According to the present invention (claim 11), in the data transmission method according to claim 10, when the receiving side detects a recovery error of the compressed information stored in the compressed packet, it recovers the data to the transmitting side. The transmitting side notifies that an error has occurred, and the transmitting side changes the number of times of continuously transmitting the uncompressed packet to the receiving side based on the frequency of notification indicating the occurrence of a decompression error from the receiving side. Continuous transmission of compressed packets can be performed efficiently.

According to the present invention (claim 12), in the data transmission method according to claim 1, after transmitting the uncompressed packet, the transmitting side includes a packet identifier and transmission information stored in the uncompressed packet. Since the auxiliary transmission packet is transmitted to the receiving side a predetermined number of times, the reliability of the transmission process for the information necessary for decompressing the compressed packet can be improved, and the quality of data transmitted wirelessly can be greatly improved. .

According to the present invention (claim 13), in the data transmission method according to claim 1, the transmitting side transmits the uncompressed packet to the receiving side with an error correction code added thereto. In the side processing, the error correction processing is performed on the uncompressed packet using the error correction code assigned thereto, so that the reliability of the transmission processing for the uncompressed packet including the information necessary for restoring the compressed packet is increased. Therefore, the quality of wirelessly transmitted data can be greatly improved.

According to the present invention (claim 14), in the data transmission method according to claim 2, the transmitting side assigns an error correction code to a packet identifier and transmission information in the uncompressed packet, and On the side, the packet identifier and the transmission information included in the uncompressed packet are subjected to error correction processing using the error correction code assigned to the packet identifier. Can be greatly improved, and thereby the quality of wirelessly transmitted data can be greatly improved.

According to the present invention (claim 15), in the data transmission method according to claim 1, when the receiving side detects a recovery error of the compressed information stored in the compressed packet, it recovers the compressed information to the transmitting side. A process of notifying that an error has occurred, and transmitting the uncompressed packet with an error correction code added thereto according to the frequency of notification indicating the occurrence of a decompression error from the receiving side, Since one of the processes of transmitting an uncompressed packet without adding an error correction code thereto is performed, the process of adding an error correction code to the uncompressed packet and the error correction process of the uncompressed packet are effectively performed. be able to.

According to the present invention (claim 16), in the data transmission method according to claim 1, on the transmission side, only the uncompressed packet is held in the retransmission buffer as retransmission data, and an error from the reception side is stored. Only when an uncompressed packet corresponding to the error packet is held in the retransmission buffer in response to the packet retransmission request, the uncompressed packet corresponding to the error packet is retransmitted to the receiving side. In addition to greatly improving the reliability of the transmission process for the information required for non-compression, retransmission of uncompressed packets can be performed efficiently, thereby greatly improving the quality of wirelessly transmitted data and the data transmission efficiency. .

According to the present invention (claim 17), in the data transmission method according to claim 2, the transmitting end uses the packet identifier and the transmission information stored in the uncompressed packet as retransmission data as a retransmission buffer. In response to a request for retransmission of the packet identifier and the transmission information stored in the error packet from the receiving side, the packet identifier and the transmission information in the uncompressed packet corresponding to the error packet are stored in the retransmission buffer. Only when this is the case, the packet identifier and the transmission information are retransmitted to the receiving side, so that the reliability of the transmission process for the information necessary for the decompression of the compressed packet is greatly improved, and the retransmission of the uncompressed packet can be performed efficiently. And the data recording capacity of the retransmission buffer can be reduced.

According to the data transmission method of the present invention (claim 18), the transmitting side continuously transmits a compressed packet containing compressed transmission information, following an uncompressed packet containing uncompressed transmission information. At this time, the compression information to be stored in the compressed packet to be transmitted is determined based on the transmission information corresponding to the reference packet, which is the uncompressed packet, and the transmission information corresponding to the target packet as the transmission target. First, the receiving side restores transmission information corresponding to the compressed packet based on the compression information included in the compressed packet and the transmission information corresponding to the reference packet.
And the transmitting side creates the compression information stored in the compressed packet by a method different from the method of creating the compressed information in the first data transmission processing, and the receiving side stores the compressed information in the compressed packet. And a second data transmission process for restoring the compressed information in the first data transmission process by a method different from the restoring method of the compressed information in the first data transmission process. The switching is performed according to the state of occurrence of an error in the restoration processing of the compressed packet on the side, so that the quality of wireless transmission data can be improved when the frequency of error is high, and the transmission information is compressed when the frequency of error is low. Efficiency can be improved.

According to the present invention (claim 19), in the data transmission method according to claim 18, the transmitting side includes, as the second data transmission process, compression information stored in the compressed packet to be transmitted. Created based on the transmission information corresponding to the previous packet transmitted immediately before the compressed packet and the transmission information corresponding to the compressed packet to be transmitted, and included on the receiving side in the compressed packet to be decompressed. Since the data transmission processing for restoring the compressed information using the transmission information corresponding to the preceding packet is performed, the compression efficiency of the transmission information can be greatly improved when the frequency of error occurrence is low.

According to the present invention (claim 20), in the data transmission method according to claim 19, when the frequency of notification of the occurrence of an error from the receiving side exceeds a certain value on the transmitting side, the first method is used. When the frequency of notification of the occurrence of the error becomes equal to or less than a certain value, the compression process in the second data transmission process is performed. Therefore, the quality of wireless transmission data when the frequency of occurrence of the error is high is reduced. It is possible to adaptively switch between a high transmission method and a transmission method with high transmission information compression efficiency when the error occurrence frequency is low.

According to this invention (Invention 21), in the data transmission method according to Claim 19, when the frequency of occurrence of a decompression processing error for the compressed packet exceeds a predetermined value, the first The second data transmission processing is performed when the error occurrence frequency of the restoration processing becomes equal to or less than a predetermined value, so that the quality of the wireless transmission data when the error occurrence frequency is high is high. And a transmission method with high transmission information compression efficiency when the frequency of occurrence of errors is low can be adaptively switched.

According to the data transmission method of the present invention (claim 22), when transmitting information in packet units, the transmitting side transmits the compressed information to be stored in the compressed packet to be transmitted to the compressed packet. It is created based on the update information related to the packet transmitted earlier and the transmission information corresponding to the compressed packet as the transmission target. At this time, the update information related to the uncompressed packet is used as an initial value of the update information. Then, every time a specific compressed packet is created, the update information is updated to information related to the specific compressed packet. On the receiving side, transmission information corresponding to the compressed packet to be decompressed is transmitted. , Using the update information related to the packet received earlier than the compressed packet, and using the update information related to the uncompressed packet as an initial value of the update information. Information, and thereafter, each time the transmission information corresponding to the specific compressed packet is restored, the update information is updated to information relating to the specific compressed packet. The improvement can improve the effective speed of data transmission, and can also increase the data compression efficiency. As a result, the time and cost required for unrecoverable packet transmission can be significantly reduced. Furthermore, by transmitting the specific compressed packet, the reference information necessary for the decompression process is updated to the compressed packet, so that the data transmission efficiency is kept high,
The compression efficiency of transmission information can be increased.

According to the present invention (claim 23), in the data transmission method according to claim 22, the compressed packet includes a reference packet identifier indicating the uncompressed packet or a specific compressed packet as a reference packet; Since the information update flag indicating whether or not the update information should be updated is stored, the receiving side can easily determine whether or not the update information should be updated based on the information update flag.

According to the present invention (claim 24), in the data transmission method according to claim 22, in the transmission-side processing, the specific compressed packet is transmitted to the reception side every time a predetermined time elapses. The increase in the amount of difference information in the compressed packet is suppressed, and the quality of the transmission data in the wireless section is improved to improve the effective data transmission speed, and the data compression efficiency can be further increased.

According to the present invention (claim 25), in the data transmission method according to claim 22, in the transmission-side processing, every time a fixed number of compressed packets are transmitted, the specific compressed packet is transmitted to the receiving side. Since the transmission is performed, an increase in the amount of difference information in the compressed packet is suppressed, so that the quality of transmission data in a wireless section is improved, the effective speed of data transmission is improved, and the data compression efficiency can be further increased.

According to the present invention (claim 26), in the data transmission method according to claim 22, in the transmission-side processing, when the transmission of the specific compressed packet is requested from the reception side, the specific compression Since the packet is transmitted to the receiving side, it is possible to improve the quality of the transmission data in the wireless section and the effective speed of the data transmission, and further increase the data compression efficiency.

According to the present invention (claim 27), in the data transmission method according to claim 22, in the transmitting process, the size of the compressed information included in the compressed packet transmitted to the receiving side exceeds a certain value. At this time, since the specific compressed packet is transmitted, it is possible to suppress an increase in the amount of difference information in the compressed packet.

According to the present invention (claim 28), in the data transmission method according to claim 22, in the transmission-side processing, the average value of the size of the compression information included in the compressed packet transmitted to the reception side is constant. When the value exceeds the value, the specific compressed packet is transmitted. Therefore, it is possible to suppress an increase in the amount of difference information in the compressed packet and to stably control the fluctuation of the difference information. Also in this case, it goes without saying that the time and cost required for packet transmission that cannot be restored can be further greatly reduced.

According to the present invention (claim 29), in the data transmission method according to claim 22, the transmission information comprises:
Including item-specific transmission information corresponding to a plurality of items, the compression information includes item-specific compression information corresponding to the plurality of items,
The item-specific compression information corresponding to each item in the compression information included in the compressed packet is used to convert the item-specific compression information corresponding to each item in the transmission information corresponding to the compressed packet into the uncompressed packet or the specific compressed packet. This is information obtained by compressing using the item-specific transmission information corresponding to each item in the corresponding transmission information, and since the item-specific compression information includes an item type flag that specifies the corresponding item, the Compression processing for information can be performed for each item, an optimal compression effect can be realized for each item, and R for storing update information and the like can be obtained.
It is possible to reduce the storage area composed of AM and the like. As a result, not only the time and cost required for packet transmission that cannot be restored can be reduced, but also the cost required for manufacturing the transmitting terminal device and the receiving terminal device can be reduced.

According to the present invention (claim 30), in the data transmission method according to claim 29, since the item-specific compression information includes data length information indicating the data length, a restoration process for the item-specific compression information is performed. Can be performed efficiently.

According to the present invention (claim 31), in the data transmission method according to claim 29, each of the item-specific compression information is a decompression corresponding to the compression method for decompressing the item-specific compression information. Since the decompression method specifying information indicating the method is included, it is possible to efficiently perform the decompression process on a plurality of item-specific compression information that has been subjected to various compression processes.

According to the data transmitting apparatus of the present invention (claim 32), the non-compressed packet in which the received transmission information is received and the predetermined transmission information is stored as the non-compression information, Packet generation means for generating a compressed packet in which the transmission information following at least a part of the transmission information is compressed and stored as compression information; and information relating to the uncompressed packet generated by the packet generation means as reference information. Reference information management means for accumulating and managing, the packet creation means, the compression information to be stored in the compressed packet to be created by the means,
Since it is created based on the transmission information corresponding to the compressed packet and the reference information stored in the reference information management means, even if a transmission error of the compressed packet occurs in the radio section, the receiving side Then, the following compressed packet is
It can be restored based on the transmission information corresponding to the uncompressed packet as the reference packet. This allows
The number of packets discarded on the receiving side due to the occurrence of an error in a wireless section can be reduced, and the quality of transmission data on a transmission path including the wireless section can be improved.

According to the data receiving apparatus of the present invention (claim 33), the data receiving apparatus receives information transmitted from the transmitting side in packet units as a transmission signal, and sequentially restores transmission information corresponding to each packet. The uncompressed packet in which the transmission signal is received and the predetermined transmission information is stored as uncompressed information, and the transmission information following the predetermined transmission information is stored as compressed information by compressing at least a part thereof. Packet receiving means for outputting a compressed packet, packet restoring means for performing a restoring process on each packet based on information stored in each of the packets, and decompressing process performed by the packet restoring means. Reference information management means for storing and managing information related to the uncompressed packet as reference information, and the packet decompression means, The transmission information corresponding to the compressed packet is reconstructed based on the compression information included in the compressed packet and the reference information stored in the reference information management means. Even if a transmission error occurs, the subsequent compressed packet can be restored based on the transmission information corresponding to the uncompressed packet as the reference packet, thereby improving the quality of the transmission data on the transmission path including the wireless section. Can be improved.

According to the data transmitting apparatus of the present invention (claim 34), an uncompressed packet in which the received transmission information is received, and the predetermined transmission information is stored as the non-compressed information, Packet generation means for generating a compressed packet in which transmission information following at least a part of the transmission information is compressed and stored as compression information, and relating to the uncompressed packet and the specific compressed packet generated by the packet generation means Information management means for managing information as update information, wherein the information management means sets information relating to the uncompressed packet as an initial value of the update information, and thereafter, every time a specific compressed packet is created. In the configuration, the update information is configured to be updated to information related to the specific compressed packet, and the packet creating unit is configured to The compressed information to be stored in the compressed packet is created based on the transmission information corresponding to the compressed packet and the update information stored in the reference information management means. In addition to improving the quality of data, the effective speed of data transmission can be improved, and the data compression efficiency can also be increased. As a result, the time and cost required for unrecoverable packet transmission can be significantly reduced. further,
By transmitting a specific compressed packet, the reference information necessary for the decompression process is updated to the compressed packet, so the number of times of transmission of the uncompressed packet is reduced, the data transmission efficiency is kept high, and the transmission information compression efficiency is improved. Can be enhanced.

According to the data receiving apparatus of the present invention (claim 35), the data receiving apparatus receives information transmitted from the transmitting side in packet units as a transmission signal, and sequentially restores transmission information corresponding to each packet. The uncompressed packet in which the transmission signal is received and the predetermined transmission information is stored as uncompressed information, and the transmission information following the predetermined transmission information is stored as compressed information by compressing at least a part thereof. Packet receiving means for outputting a compressed packet, packet restoring means for performing a restoring process on each packet based on information stored in each of the packets, and decompressing process performed by the packet restoring means. Reference information management means for accumulating and managing information relating to uncompressed packets and specific compressed packets as reference information; The information management means sets information relating to the uncompressed packet as an initial value of the update information, and thereafter, every time a decompression process is performed on the specific compressed packet, the update information is added to the specific compressed packet. The packet decompression unit is configured to update transmission information corresponding to the compressed packet with the compression information included in the compressed packet and the reference information stored in the reference information management unit. Based on the configuration based on the restoration, while improving the quality of the transmission data in the wireless section to improve the effective speed of data transmission,
The data compression efficiency can also be improved, and as a result, the time and cost required for unrecoverable packet transmission can be significantly reduced. Further, each time a specific compressed packet is restored, the reference information necessary for the restoration processing is updated to the compressed packet, so that the number of times of transmitting the non-compressed packet is reduced, and the data transmission efficiency and the transmission information compression efficiency are reduced. High transmission processing can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a data transmission method according to a first embodiment of the present invention, in which an uncompressed packet (FIG. 1A) and a compressed packet (FIG.
(b)) shows the data structure.

FIG. 2 is a block diagram for explaining a data transmission system using the data transmission method according to the first embodiment;
2 shows a data transmission device in the data transmission system.

FIG. 3 is a block diagram for explaining a data transmission system using the data transmission method according to the first embodiment;
2 shows a data receiving device in the data transmission system.

FIG. 4 is a diagram for explaining the data transmission method according to the first embodiment, and shows a flow of a plurality of packets from a transmission side to a reception side in a normal transmission state.

FIG. 5 is a diagram for explaining a data transmission method according to the first embodiment, showing a flow of a plurality of packets from a transmission side to a reception side when a transmission error occurs.

FIG. 6 is a diagram showing a flow of a packet creation process in the data transmitting apparatus of the first embodiment.

FIG. 7 is a diagram showing a flow of a packet restoration process in the data receiving device of the first embodiment.

FIG. 8 is a diagram for explaining a data transmission method according to a first modification of the first embodiment of the present invention, in which an uncompressed packet (FIG. (A)) and a compressed packet (FIG. The data structure shown in FIG.

FIG. 9 is a diagram for explaining a data transmission method according to a first modification of the first embodiment, and shows a flow of a plurality of packets from a transmission side to a reception side in a normal transmission state.

FIG. 10 is a diagram for explaining a data transmission method according to a second modification of the first embodiment of the present invention, wherein an uncompressed packet (FIG. (A)) and a compressed packet (FIG. The data structure shown in FIG.

FIG. 11 is a diagram for explaining a data transmission method according to a third modification of the first embodiment of the present invention, wherein an uncompressed packet (FIG. (A)) and a compressed packet (FIG. The data structure shown in FIG.

FIG. 12 is a block diagram for explaining a data transmission system using a data transmission method according to a second embodiment of the present invention, and shows a data transmission device in the data transmission system.

FIG. 13 is a diagram for explaining a data transmission method according to the second embodiment, and shows a flow of a plurality of packets from a transmission side to a reception side in a normal transmission state.

FIG. 14 is a block diagram for explaining a data transmission system using a data transmission method according to a third embodiment of the present invention, and shows a data transmission device in the data transmission system.

FIG. 15 is a block diagram for explaining a data transmission system using the data transmission method according to the third embodiment, and shows a data receiving device in the data transmission system.

FIG. 16 is a block diagram for explaining a data transmission system using a data transmission method according to a fourth embodiment of the present invention, and shows a data transmission device in the data transmission system.

FIG. 17 is a block diagram for explaining a data transmission system using the data transmission method according to the fourth embodiment, and shows a data receiving device in the data transmission system.

FIG. 18 is a diagram for explaining a data transmission method according to the fifth embodiment of the present invention, wherein an uncompressed packet (FIG. 13A) and a compressed packet (FIG.
(b)) shows the data structure.

FIG. 19 is a block diagram for explaining a data transmission system using the data transmission method of the fifth embodiment, and shows a data transmission device in the data transmission system.

FIG. 20 is a block diagram for explaining a data transmission system using the data transmission method according to the fifth embodiment, and shows a data receiving device in the data transmission system.

FIG. 21 is a diagram for explaining a data transmission method according to the fifth embodiment, and shows a flow of a plurality of packets from a transmission side to a reception side in a normal transmission state.

FIG. 22 is a diagram for explaining a data transmission method according to the fifth embodiment, and shows a flow of a plurality of packets from a transmission side to a reception side when a transmission error occurs.

FIG. 23 is a diagram illustrating a flow of a packet creation process in the data transmission device of the fifth embodiment.

FIG. 24 is a diagram showing a flow of a packet restoration process in the data receiving apparatus of the fifth embodiment.

FIG. 25 is a diagram for explaining a data transmission method according to a modification of the fifth embodiment of the present invention, wherein an uncompressed packet (FIG. (A)) and a compressed packet (FIG. (b)) Data structure and transmission information D (Y)
To create a compressed packet Pj (Y) by compressing
(c)).

FIG. 26 is an enlarged view showing a part of a compressed packet Pj (Y) according to a modification of the fifth embodiment.

FIG. 27 is a diagram illustrating transmission information (FIG. 17A) to be transmitted and a non-compressed packet Pi in the modification of the fifth embodiment.
And specific information stored in the compressed packet Pj (FIG.
It is a figure for explaining (b)).

FIG. 28 is a diagram for explaining a conventional data transmission system to which V. Jacobson header compression is applied, the overall configuration of the data transmission system (FIG. 12A), and data transmission in the data transmission system; Processing required for processing (Figure (b))
Is shown.

FIG. 29 is a diagram showing the data structure of a packet used in the conventional data transmission system, and is an RTP packet (FIG. (A)), a UDP packet (FIG. (B)), and an IP packet (FIG. (C), FIG. (d)) and a PPP packet (FIG. (e)).

FIG. 30 is a diagram showing the data structure of a PPP packet used in a conventional data transmission system to which V. Jacobson header compression is applied, and shows an uncompressed packet (FIG. (A)) and a compressed packet (FIG. (B) )).

FIG. 31 is a diagram for conceptually explaining a conventional PPP packet transmission process using the V. Jacobson header compression method.

FIG. 32 is a diagram for explaining a case where a transmission error occurs in a conventional PPP packet transmission process using the V. Jacobson header compression method.

FIG. 33 is a diagram for explaining a data transmission system having a wireless transmission section to which conventional V. Jacobson header compression is applied, and shows the overall configuration of the data transmission system (FIG. (A)); Fig. 3 shows processing (Fig. (B)) necessary for data transmission in the data transmission system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Receiving means 12 Compressed / uncompressed packet creation means 13 Compressed / uncompressed transmission determining means 14 Error occurrence notification receiving means 15 Reference information managing means 16 Packet transmitting means 17 Reference information update determining means 21 Packet receiving means 22 Error packet detecting means 23 Packet restoration means 24 Error occurrence notification transmission means 25 Reference information management means 26 Output means 31 Uncompressed packet transmission count monitoring means 32 Error correction code addition means 41 Error correction means 42 Restoration waiting information storage means 101, 102, 103, 104, 105 Data transmitting device 201, 203, 204, 205 Data receiving device Cm1 Transmission-side management control signal Cm2 Reception-side management control signal Dcp Compressed data Dpa, Dpaa, Dpb, Dpbb, Dpc, Dpd, Dpe, Dp
f, Dpg, Dph, Dpi data part Hpa, Hpaa, Hpb, Hpbb, Hpc, HPd, Hpe, Hp
f, Hpg, Hph, Hpj Header Ico1 Subsequent difference information presence flag Ico2 Reference information type flag Id Compression information (difference information (ΔD)) Ida, Idb, Idc, Idd Item-specific compression information Id1 First compression information (difference information (Δ1D)) Id2 Second compressed information (difference information (Δ2D)) Ih1 Compressed / uncompressed identifier Ih2a Packet identifier (ID) Ih2b First reference packet identifier (ID1) Ih2b1 Second reference packet identifier (ID2) Ih2b2 Reference packet identifier (ID) Ih3 Other header information Ih4 Difference specifying additional information Ih5 Reference information update flag Ih6 Difference information presence / absence flag Im1 Transmitter reference information Im2 Reception item reference information Inc Non-compression target information Ir Uncompressed information (transmission information (D )) Ira, Irb, Irc, Ird Compression target information by item Irs restoration information (transmission information (D)) Iun1 Difference information length data Iun2 Compression method type flag Jp Packet discrimination signal Jr Reference information update signal K1 to K4 First to fourth compression target items Ne Decompression error notification signal Nr Retransmission request notification signal Pa, Pa (1), Paa ( 1), Pc, Pe, Pg, P
g (1), Pi, Pi (1) Uncompressed packet Pac ECC added uncompressed packet Pb, Pb (2) to Pb (4), Pbb (2) to Pbb
(4), Pd, Pf, Ph, Ph (2) to Ph (1
1), Pj, Pj (Y), Pj (2), Pj (3) Compressed packet Pno Normal packet Pre Restoration error packet Rp Received packet S1, S2 First and second transmission signal S3 Output signal Sc Re-creation command signal Se error occurrence signal Sn error notification reception signal Sr retransmission request reception signal Src reception signal

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kirsten Blumeister, Germany Darmstadt D-64295 Schep Aare 47 (72) Inventor Loaf Hackenberg, Germany Darmstadt D-64295 Kurzell Weg 3F Term ( Reference) 5K014 AA01 BA06 FA11 5K030 HA08 JA05 LA07

Claims (35)

[Claims] 1. A data transmission method for sequentially transmitting information from a transmitting side to a receiving side for each piece of transmission information corresponding to a packet, comprising transmitting an uncompressed packet in which predetermined transmission information is stored as uncompressed information. A transmitting side process of continuously transmitting a compressed packet in which at least a part of the transmission information following the predetermined transmission information is compressed and stored as compression information; and receiving each packet from the transmission side, And a receiving side process for restoring transmission information corresponding to each packet based on the uncompressed information and the compressed information stored in the compressed packet to be transmitted. A compression process for creating information based on transmission information corresponding to a reference packet, which is the uncompressed packet, and transmission information corresponding to a target packet to be transmitted. Wherein the receiving-side process decompresses transmission information corresponding to the compressed packet to be decompressed based on the transmission information corresponding to the reference packet and the compression information included in the decompressed compressed packet. A data transmission method comprising a restoration process. 2. The data transmission method according to claim 1, wherein, in the transmission-side processing, a packet including a packet identifier indicating the packet together with the uncompressed information is transmitted as the uncompressed packet. As each subsequent compressed packet,
A packet including a reference packet identifier indicating an uncompressed packet as the reference packet together with the compression information is transmitted. In the compression processing, the compression information corresponds to the transmission information corresponding to the reference packet and the compression packet. A data transmission method characterized by creating difference information from transmission information. 3. The data transmission method according to claim 2, wherein, in the transmission-side processing, additional information for calculating the difference information based on transmission information corresponding to the reference packet is stored in the compressed packet. And a receiving-side process for calculating difference information in the compressed packet from transmission information corresponding to the reference packet based on additional information in the compressed packet. 4. The data transmission method according to claim 3, wherein the additional information is a sequence capable of identifying an order number of the compressed packet transmitted after transmission of the uncompressed packet as the reference packet. A data transmission method characterized by being a number. 5. The data transmission method according to claim 3, wherein the additional information is a variable of a calculation formula for calculating difference information in the compressed packet from transmission information corresponding to the reference packet. Transmission method. 6. The data transmission method according to claim 2, wherein in the transmitting side processing, a plurality of uncompressed packets created to be transmitted before the compressed packet are used as reference packets, and Is associated with difference information between the transmission information corresponding to each of the reference packets and the transmission information corresponding to the compressed packet, and a reference packet identifier corresponding to each of the reference packets. Is stored as a plurality of sets of the compressed information, and in the receiving-side processing, the transmission information corresponding to the compressed packet is restored using the differential information and the packet identifier of one of the sets in the compressed packet. Data transmission method. 7. The data transmission method according to claim 1, wherein, in the transmission-side processing, the uncompressed packet is transmitted at a constant cycle. 8. The data transmission method according to claim 1, wherein in the transmitting side processing, when the size of the compressed information included in the compressed packet transmitted to the receiving side exceeds a certain value, the uncompressed packet is transmitted. A data transmission method. 9. The data transmission method according to claim 1, wherein in the receiving side processing, when the size of the compressed information included in the compressed packet from the transmitting side exceeds a certain value, the transmitting side transmits the uncompressed packet to the transmitting side. A data transmission method comprising: requesting transmission; and transmitting the uncompressed packet to the receiving side when receiving the request for transmitting the uncompressed packet from the receiving side. 10. The data transmission method according to claim 1, wherein in the transmission side processing, an uncompressed packet storing the same transmission information is transmitted to the reception side a plurality of times in succession. . 11. The data transmission method according to claim 10, wherein in the receiving-side processing, when detecting a decompression error of the compression information stored in the compressed packet, the transmission side is notified of the occurrence of the decompression error. In the transmitting process, the number of times the uncompressed packet is continuously transmitted to the receiving side is changed based on the frequency of notification indicating the occurrence of a decompression error from the receiving side. . 12. The data transmission method according to claim 1, wherein, in the transmission-side processing, after transmitting the uncompressed packet, an auxiliary transmission packet including a packet identifier and transmission information stored in the uncompressed packet is transmitted a predetermined number of times. A data transmission method for transmitting to a receiving side. 13. The data transmission method according to claim 1, wherein, in the transmitting side processing, the uncompressed packet is transmitted to a receiving side with an error correction code added thereto. A data transmission method comprising performing an error correction process on a packet using an error correction code assigned to the packet. 14. The data transmission method according to claim 2, wherein in the transmitting side processing, an error correction code is added to a packet identifier and transmission information in the uncompressed packet, and in the receiving side processing, A data transmission method, wherein an error correction process is performed on a packet identifier and transmission information included in a compressed packet using an error correction code assigned thereto. 15. The data transmission method according to claim 1, wherein the receiving side processing notifies the transmitting side of the occurrence of a decompression error when detecting a decompression error of the compression information stored in the compressed packet. In the transmitting side processing, the uncompressed packet is transmitted with an error correction code added thereto according to the frequency of notification indicating the occurrence of a decompression error from the receiving side. A data transmission method for performing one of transmission processes without adding an error correction code to the data. 16. The data transmission method according to claim 1, wherein in the transmitting side processing, only the uncompressed packet is held as retransmission data in a retransmission buffer, and in the receiving side processing, the transmission of the uncompressed packet is performed. When an error is detected, a request is made to the transmitting side to retransmit an uncompressed packet that is an error packet. When the transmitting side process receives the retransmission request for the error packet, the non-compressed packet corresponding to the error packet is received. Only if the packet is held in the retransmission buffer,
A data transmission method comprising retransmitting an uncompressed packet corresponding to the error packet to a receiving side. 17. The data transmission method according to claim 2, wherein, in the transmission-side processing, a packet identifier and transmission information stored in the uncompressed packet are held as retransmission data in a retransmission buffer; In the processing, when a transmission error of the uncompressed packet is detected, the transmitting side requests the transmitting side to retransmit a packet identifier and transmission information stored in the uncompressed packet which is an error packet. When the packet identifier and the transmission information are received, the packet identifier and the transmission information are received only when the packet identifier and the transmission information in the uncompressed packet corresponding to the error packet are held in the retransmission buffer. A data transmission method characterized by resending to the side. 18. A data transmission method for sequentially transmitting information from a transmission side to a reception side for each piece of transmission information corresponding to a packet, comprising transmitting an uncompressed packet in which predetermined transmission information is stored as uncompressed information. A transmitting side process for continuously transmitting a compressed packet in which at least a part of the transmission information subsequent to the predetermined transmission information is compressed and stored as compression information, and receiving each packet from the transmission side, Based on the uncompressed information and the compressed information stored in the packet,
Receiving side processing for restoring transmission information corresponding to each packet. In the transmitting side processing, compressed information to be stored in a compressed packet to be transmitted corresponds to a reference packet which is the uncompressed packet. Created based on the transmission information and the transmission information corresponding to the compressed packet as the transmission target, and in the reception-side processing, the transmission information corresponding to the compression packet to be decompressed is converted into the transmission information corresponding to the reference packet. A first data transmission process for decompressing based on the compression information included in the compressed packet to be decompressed;
The compression information is created by a method different from the method of creating the compressed information in the first data transmission process, and the compression information stored in the compressed packet is received on the receiving side by the compression information decompression method in the first data transmission process. And a second data transmission process for decompressing by a different method. When the transmission information is transmitted in a packet, the first and second data transmission processes may be decompressed on the receiving side with respect to a compressed packet. A data transmission method characterized by switching according to a situation and performing one of the first and second data transmission processes. 19. The data transmission method according to claim 18, wherein, in the second data transmission process, the compression information stored in the compressed packet to be transmitted is transmitted immediately before the compressed packet as a transmission side process. Including a compression process created based on the transmission information corresponding to the transmitted previous packet and the transmission information corresponding to the compressed packet as the transmission target, the compression included in the compression packet to be decompressed as the reception-side process A data transmission method including a restoration process for restoring information using transmission information corresponding to the previous packet. 20. The data transmission method according to claim 19, wherein when an error occurs in a decompression process for decompressing the compression information included in the compressed packet on the reception side, the reception side notifies the transmission side of the occurrence of the error. On the transmitting side, when the error notification frequency exceeds a certain value, the transmitting side issues a process change notification to the receiving side to change the restoring process on the receiving side to the restoring process in the first data transmission process. The side performs compression processing in the first data transmission processing. On the transmission side, when the frequency of notification of error occurrence falls below a certain value, the restoration processing on the reception side is performed by the second data transmission apparatus. A process change notification is sent to the receiving side to change to the process.
A data transmission method comprising performing a compression process in the data transmission process. 21. The data transmission method according to claim 19, wherein, on the receiving side, when an error occurrence frequency at which an error of a decompression process for decompressing the compression information included in the compressed packet occurs exceeds a predetermined value, the transmission side. Compression processing in the first
Requesting the transmission side to change to the compression processing in the data transmission processing of the above. On the other hand, when the error occurrence frequency of the above-mentioned decompression processing becomes equal to or less than a predetermined value, the reception side executes the compression processing on the transmission side in the second Requesting the transmission side to change to the compression processing in the data transmission processing, and the transmission side responds to the processing change request from the reception side in the compression processing in the first and second data transmission processing. A data transmission method comprising performing compression processing in data transmission processing. 22. A data transmission method for sequentially transmitting information from a transmitting side to a receiving side for each piece of transmission information corresponding to a packet, comprising transmitting an uncompressed packet in which predetermined transmission information is stored as uncompressed information. A transmitting side process for continuously transmitting a compressed packet in which at least a part of the transmission information following the predetermined transmission information is compressed and stored as compression information, and receiving each packet from the transmission side, Receiving side processing for restoring transmission information corresponding to each packet based on the uncompressed information and compressed information stored in the packet, wherein the transmitting side processing is stored in a compressed packet to be transmitted. Compression information to be generated based on update information related to a packet transmitted before the compressed packet and transmission information corresponding to the compressed packet to be transmitted. Compression processing, and setting information related to the uncompressed packet as an initial value of the update information. Thereafter, every time a specific compressed packet is created, the update information is added to information related to the specific compressed packet. And updating the transmission information corresponding to the compressed packet to be decompressed using the update information related to the packet received earlier than the compressed packet. Processing, and setting the information related to the uncompressed packet as an initial value of the update information, and thereafter, whenever the transmission information corresponding to the specific compressed packet is restored, the update information is stored in the specific compressed packet. And a receiving side updating process for updating to information related to the data transmission. 23. The data transmission method according to claim 22, wherein the update information includes a reference packet identifier indicating the uncompressed packet or a specific compressed packet as a reference packet, and transmission information corresponding to the reference packet. The compressed packet includes a reference packet identifier indicating the uncompressed packet or the specific compressed packet as a reference packet, and an information update flag indicating whether or not to update the update information. The information update flag in the packet is set to a value indicating that the update information should be updated, and the information update flag in a compressed packet other than the specific compressed packet indicates that the update information should not be updated. A data transmission method characterized by being set to a value. 24. The data transmission method according to claim 22, wherein in the transmission-side processing, the specific compressed packet is transmitted to a reception side every time a predetermined time elapses. 25. The data transmission method according to claim 22, wherein in the transmission-side processing, the specific compressed packet is transmitted to a receiving side every time a fixed number of compressed packets are transmitted. Method. 26. The data transmission method according to claim 22, wherein in the transmission-side processing, when a transmission of the specific compressed packet is requested from a receiving side, the specific compressed packet is transmitted to the receiving side. Characteristic data transmission method. 27. The data transmission method according to claim 22, wherein, in the transmitting side processing, when the size of the compressed information included in the compressed packet transmitted to the receiving side exceeds a certain value, the specific compressed packet is transmitted. A data transmission method characterized by transmitting. 28. The data transmission method according to claim 22, wherein in the transmission side processing, when the average value of the size of the compressed information included in the compressed packet transmitted to the receiving side exceeds a certain value, the specific processing is performed. A data transmission method comprising transmitting a compressed packet. 29. The data transmission method according to claim 22, wherein the transmission information includes item-specific transmission information corresponding to a plurality of items, and the compression information includes item-specific compression information corresponding to a plurality of items. The item-specific compressed information corresponding to each item in the compressed information included in the compressed packet is the item-specific compressed information corresponding to each item in the transmission information corresponding to the compressed packet, the uncompressed packet or the specific compressed packet. Is obtained by compressing using the item-specific transmission information corresponding to each item in the transmission information corresponding to the item, wherein the item-specific compression information includes an item type flag for specifying the corresponding item. Characteristic data transmission method. 30. The data transmission method according to claim 29, wherein the item-specific compression information includes data length information indicating the data length. 31. The data transmission method according to claim 29, wherein the item-specific compression information is created using a compression method corresponding to each of a plurality of compression methods. A data transmission method, wherein the compression information includes decompression method specifying information indicating a decompression method corresponding to the compression method for decompressing the item-specific compression information. 32. A data transmitting apparatus for sequentially transmitting information to a receiving side for each piece of transmission information corresponding to a packet, a receiving means for receiving the transmission information as an input signal, and receiving the received transmission information; Uncompressed packet in which predetermined transmission information is stored as uncompressed information, and packet creation for generating a compressed packet in which at least a part of transmission information following the predetermined transmission information is compressed and stored as compressed information Means, reference information management means for storing and managing, as reference information, information relating to the uncompressed packet created by the packet creation means, and receiving each packet created by the packet creation means as a transmission signal. Transmitting means for transmitting the compressed information to the compressed packet to be generated by the means. The data transmission device comprising a transmission information corresponding to the compressed packet, to create on the basis of the reference information stored in the reference information management unit. 33. A data receiving apparatus for receiving information transmitted in packet units from a transmitting side as a transmission signal and sequentially restoring transmission information corresponding to each packet, the data receiving apparatus comprising: An uncompressed packet in which information is stored as uncompressed information, and packet receiving means for outputting a compressed packet in which at least a part of the transmission information following the predetermined transmission information is compressed and stored as compression information, A packet restoration unit that receives an output of the packet reception unit, performs restoration processing on each packet based on information stored in each packet, and outputs transmission information corresponding to each packet; Reference information management means for storing and managing information relating to the uncompressed packet subjected to the decompression processing by the packet decompression means as reference information, Output means for outputting transmission information corresponding to each of the packets from the packet decompression means, wherein the packet decompression means transmits transmission information corresponding to the compressed packet, compression information included in the compressed packet, A data receiving apparatus for performing restoration based on reference information stored in reference information management means. 34. A data transmitting apparatus for sequentially transmitting information to a receiving side for each piece of transmission information corresponding to a packet, comprising: a receiving means for receiving the transmission information as an input signal; Uncompressed packet in which predetermined transmission information is stored as uncompressed information, and packet creation for generating a compressed packet in which at least a part of transmission information following the predetermined transmission information is compressed and stored as compressed information Means; information management means for managing information relating to the uncompressed packet and the specific compressed packet created by the packet creation means as update information; and receiving the packet created by the packet creation means as a transmission signal. Transmission means for transmitting the information to the non-compressed packet as an initial value of the update information. And thereafter, each time a specific compressed packet is generated, the update information is updated to information related to the specific compressed packet. The compression information to be stored in the target compressed packet is created based on transmission information corresponding to the compressed packet and update information stored in the reference information management means. Data transmission device. 35. A data receiving apparatus for receiving information transmitted in packet units from a transmitting side as a transmission signal and sequentially restoring transmission information corresponding to each packet, the data receiving apparatus comprising: An uncompressed packet in which information is stored as uncompressed information, and packet receiving means for outputting a compressed packet in which at least a part of the transmission information following the predetermined transmission information is compressed and stored as compression information, A packet restoration unit that receives an output of the packet reception unit, performs restoration processing on each packet based on information stored in each packet, and outputs transmission information corresponding to each packet; Information relating to the uncompressed packet and the specific compressed packet subjected to the restoration processing by the packet restoration means is stored and managed as reference information. Reference information management means, and output means for outputting transmission information corresponding to each packet restored by the packet restoration means, wherein the information management means relates to the uncompressed packet as an initial value of the update information. After that, every time the decompression process for the specific compressed packet is performed,
The update information is configured to be updated to information related to the specific compressed packet, and the packet decompression means converts transmission information corresponding to the compressed packet into compression information included in the compressed packet, A data receiving apparatus configured to perform restoration based on reference information stored in an information management unit.