JP2008113152A - Transmission method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission method and a transmission device capable of obtaining an optimum compression rate in ROHC compression when applying ROHC in a path for making an IP packet path wireless. <P>SOLUTION: There are provided: a packet filter 27 grasping a first packet to be compressed among packets acquired by a client PC 13 successively; an IP-ID determination section 32 for obtaining a second identification number where a prescribed number is added to a first identification number given to the packet when the packet is grasped; an IP-ID rewrite section 33 for changing the first identification number to the second one and giving the second identification number successively to a packet to be compressed from the first packet to be compressed; an ROHC compression section 20 for successively compressing a packet to which the second identification number is given; and a radio communication section 18 for transmitting the packet compressed by the ROHC compression section 20 to a receiver. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission method and apparatus, and more particularly, to a transmission method and apparatus based on Internet Protocol (IP).

Conventionally, various communication techniques for transmitting data from the transmitter side to the receiver side have been devised. Recently, however, the IP-based method is preferred for reasons such as packet orientation and the degree of freedom of the transmission destination. Yes.
Also, when the purpose of transmission is media packet transmission such as voice and moving images, the user datagram protocol (UDP) is used with the IP packet as the lower layer, and the real-time transport protocol is used as the communication method of the higher layer. (Real time Transport Protocol: RTP) is preferably used.

Media packet transmission using RTP / UDP / IP has become the de facto standard, and although there are many cases where this method is often selected to ensure many operational commonities, the overhead is relatively low. It gets bigger.
As a method for reducing the overhead of RTP / UDP / IP and transmitting media packets over a transmission path having a narrower band, for example, “header compression method and apparatus and program” (see Patent Document 1) and “ Several packet header compression methods have been devised, such as "Method, Apparatus, and System for Transmitting Compressed Header Data" (see Patent Document 2), among which Robust Header Compression (ROHC) is included. .

  ROHC pays attention to the consistency of RTP / UDP / IP headers between consecutive packets, and information that can be inferred without repeatedly transmitting information that can be inferred by information that has already been transmitted, information that can be inferred, and information that is obtained by calculation The packet header information to be transmitted is compressed by transmitting information for inferring and information that cannot be inferred and changes each time. Here, one of the information that can be inferred is the identification number (IP-ID) in the IP header in the profile 1 (RTP profile) of ROHC (RFC3095).

  Recently, a wireless device for making a part of an IP route wireless has become a common technology, and one of them is PHS (Personal Handyphone System). In this PHS, a client PC (Client Personal Computer) looks like a modem, and an OS (Operating System) such as Windows (a registered trademark of WINDOWS (registered trademark) or Microsoft) operating on the client PC is connected to the Internet. Intermediary.

In general, a general-purpose OS such as Windows can execute a VoIP (Voice over Internet Protocol) application. The VoIP application can perform a VoIP call with a SIP (Session Initiation Protocol) telephone on the Internet using, for example, G729A (8 Kbps) as a codec and RTP / UDP / IP.
Generally, a general-purpose OS such as Windows uses the same IP-ID system for an IP-ID used in TCP (Transmission Control Protocol) or ICMP (Internet Control Message Protocol) and a UDP packet used in VoIP.
JP 2002-204260 A JP 2003-304299 A

In the above-described conventional communication system, when ROHC is applied on a route that makes an IP packet route wireless, it is possible to obtain a compression rate that is more favorable when the IP-ID continuously changes.
However, generally, the OS of the client PC determines whether or not the IP-ID is a target RTP / UDP / IP packet and is a continuous number, and cannot be determined by the VoIP application or the transmission path. Therefore, when a target IP packet other than VoIP, such as ICMP or TCP, is generated, the change in IP-ID is not a continuous change, and an optimal compression rate cannot be obtained in ROHC compression.
An object of the present invention is to provide a transmission method and apparatus capable of obtaining an optimal compression ratio in ROHC compression when ROHC is applied in a route for wirelessly converting an IP packet route.

  To achieve the above object, a transmission method according to the present invention includes a packet acquisition step of sequentially acquiring packets to be transmitted in the transmission method of sequentially assigning and transmitting a first identification number that is consecutive for each packet to be sequentially transmitted. The first grasping step for grasping the compression target packet among the packets obtained in the packet obtaining step, and the second grasping the first compression target packet among the compression subject packets grasped in the first grasping step. When the first compression target packet is grasped in the grasping step and the second grasping step, the first identification number given to the first compression target packet is changed to the first identification number. Change to a second identification number to which a predetermined number is added, and sequentially assign the second identification number to the compression target packets after the first compression target packet With another number change step, the identification number the change step second identification numbers sequentially compress the compressed packet granted, is characterized in that it comprises a compressed packet transmission step of transmitting.

In the present invention, after the identification number changing step, the first identification number assigned to each packet sequentially acquired in the packet acquisition step and a match between the second identification number and the second identification number are grasped. 3 and the second identification number assigned to the compression target packet when the first identification number and the second identification number match based on the determination. Changing the identification number to a third identification number obtained by adding a predetermined number to the second identification number, and subsequently changing the second identification number to sequentially assign the third identification number to the subsequent packets to be compressed It is preferable that after the second identification number changing step, the packets to be compressed to which the third identification number is assigned are sequentially compressed and transmitted.
In the present invention, it is preferable that the compression target packet is a user datagram protocol (User Datagram Protocol) packet.

  In addition, the transmission device according to the present invention includes a packet acquisition unit that sequentially acquires packets to be transmitted in the transmission device that sequentially assigns a first identification number for each packet to be sequentially transmitted and transmits the packet to the reception device, The grasping means for grasping the first packet to be compressed among the packets obtained by the packet obtaining means; and the grasping means for grasping the first packet to be compressed, the above-mentioned attached to the first packet to be compressed A second identification number calculating means for obtaining a second identification number obtained by adding a predetermined number to the first identification number; and the first identification number assigned to the first packet to be compressed, the second identification number The second identification number is changed to the second identification number obtained by the number calculation means, and the second identification number is sequentially assigned to the compression target packets after the first compression target packet. Number changing means, packet compression means for sequentially compressing the packet to be compressed to which the second identification number is given by the identification number changing means, and compression for transmitting the packet compressed by the packet compression means to the receiving device And a packet transmission means.

  According to the present invention, when ROHC is applied to a route that makes an IP packet route wireless, an extra change can be obtained by continuously changing the IP-ID of an RTP / UDP / IP packet intended for ROHC compression. Since it is not necessary to send information, the bandwidth does not increase, and an optimal compression rate can be obtained in ROHC compression.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory diagram showing a schematic configuration of a wireless communication system using a wireless terminal device according to an embodiment of the present invention. As illustrated in FIG. 1, a wireless communication system 11 using a wireless terminal device (transmitting device) 10 includes a wireless base station 12 that is wirelessly connected to the wireless terminal device 10, a client PC 13 that is connected to the wireless terminal device 10, A voice telephone 14 connected to the client PC 13, a SIP server 15 connected to the wireless base station 12 via the Internet, an opposing SIP telephone 16, and a PDSN (Packet Data Serving Node) 17 connected to the wireless base station 12 Have.
The voice communication device 14 is a telephone for VoIP calls that is commercially available nowadays, and includes a speaker for reception, a microphone for transmission, a keypad for various operations, a USB interface for connection with the client PC 13, and the like. I have.

The client PC 13 functions as a PPPoE client (Point-to-Point Protocol over Ethernet Client) and is connected to the wireless terminal device 10 via Ethernet (registered trademark) (Ethernet (registered trademark)).
The wireless terminal device 10 has a PPPoE server function and accepts a connection request from PPPoE. That is, the wireless terminal device 10 is connected to the wireless base station 12 through a wireless link, and transmits the PPP packet from the client PC 13 to the PDSN 17. The PDSN 17 functions as a PPP server and a DHCP (Dynamic Host Configuration Protocol) server, accepts a PPP connection request from the client PC 13, and passes a global IP address to the client PC 13. The client PC 13 connects to the Internet using a global IP address.

  The client PC 13 is installed with a VoIP application corresponding to the SIP protocol, and communicates with the SIP server 15 and the opposite SIP telephone 16 via the SIP protocol. After the call connection request from the client PC 13 is connected to the opposite SIP telephone 16 under the guidance of the SIP server 15, the speaker and microphone of the voice communication device 14 connected to the client PC 13 by USB I / F (Universal Serial Bus interface). Is used to implement a voice call with the opposite SIP telephone 16. As the voice codec, G729A (8 Kbps) is used.

  FIG. 2 is an explanatory diagram showing an example of a protocol stack transition process during a VoIP call using the wireless communication system of FIG. As shown in FIG. 2, when performing a VoIP call using the wireless communication system 11, the client PC 13 converts the voice data obtained from the microphone into digital data using the G729 codec, and packs it into an RTP / UDP / IP packet. To do. The PPPoE client of the client PC 13 encapsulates the RTP / UDP / IP packet into a PPPoE / IP packet and transmits it to the wireless terminal device 10 using Ethernet as a link channel.

  After encapsulating the PPPoE packet, the wireless terminal device 10 performs ROHC compression on each RTP / UDP / IP header and transmits the header to the wireless base station 12 using a wireless protocol. The radio base station 12 constructs an A10 / GRE (General Routing Encapsulation) packet from the data received from the radio terminal device 10. At this time, the ROHC packet that is ROHC compressed is expanded into an RTP / UDP / IP packet. The A10 / GRE packet is transmitted to the PDSN 17 using Ethernet as a link channel.

FIG. 3 is a block diagram showing an internal structure of the wireless terminal device of FIG. As illustrated in FIG. 3, the wireless terminal device 10 includes a wireless communication unit 18, a transmission buffer 19, a ROHC compression unit 20, a transmission channel context holding unit 21, a reception packet buffer 22, a PPP determination unit 23, a ROHC expansion unit 24, a reception It includes a channel context holding unit 25, a PPP packet construction unit 26, a packet filter 27, a PPP packet extraction processing unit 28, a PPPoE packet construction unit 29, a PC I / F unit 30, and an IP-ID processing unit 31.
The IP-ID processing unit 31 includes an IP-ID determination unit 32, an IP-ID rewriting unit 33, and a changeover switch 34.

  The PC I / F unit 30 has a function of receiving an Ethernet packet received from the Ethernet. Since the Ethernet packet received from the PC I / F unit 30 is a PPPoE packet, it is encapsulated by the PPP packet extraction processing unit 28 into a PPP packet. The client PC 13 uses the protocol type of the PPPoE packet as an IP packet. The packet filter 27 determines whether or not the packet needs ROHC compression by referring to the header information of the PPP packet. In general, it is possible to determine whether or not the packet is for compression by referring to the protocol field of the IP header, the payload type of the RTP packet, and the like.

  When the packet filter 27 determines that the PPP packet is the ROHC compression target packet, the packet filter 27 rewrites the protocol type of the PPP packet to the ROHC protocol, and the ROHC compression unit 20 performs compression. If the packet filter 27 determines that the PPP packet is not a ROHC compression target packet, the packet protocol 27 does not rewrite the PPP protocol type as IP, and does not allow the ROHC compression unit 20 to pass through (uncompressed). In any case, the PPP packet is stored in the transmission buffer 19 and sequentially transmitted to the radio base station 12.

Next, the IP-ID processing unit 31 will be described. Regarding PPP packet processing, the packet filter 27 refers to the contents of the PPP packet to determine whether or not the packet requires ROHC compression. If ROHC compression is necessary, the protocol type of PPP is rewritten to the ROHC protocol. The process up to this point is the same as when the IP-ID processing unit 31 is not provided, but the IP-ID processing unit 31 rewrites the IP-ID to a number managed for each context ID.
By performing such control, the IP-ID can be rewritten from the original IP-ID according to the setting. One specific method of rewriting the IP-ID will be described with reference to FIG.

  FIG. 4 is an explanatory diagram showing a domain space when the IP-ID is rewritten by the wireless terminal device according to the present invention. As shown in FIG. 4, the IP-ID is a 16-bit address space and has a domain from 0000h to FFFFh. In addition, after FFFFh, since it returns to 0000h, it can be represented by a circle. When the packet filter first recognizes an RTP / UDP / IP packet that is subject to ROHC compression and performs ROHC compression, the ROHC compression unit 20 assigns an ID called a context ID to the RTP session. This context ID is allocated independently for each context in ROHC.

  When a new context is generated and a context ID is allocated, the IP-ID (first identification number) at that time is defined as id_primary_start, and a number obtained by adding 4000h to the number is id_cid1_start (start of the second identification number) And That is, the IP-ID of the IP at the start of context ID1 is set to id_primary_start, and the context ID1 start IP-ID is id_cid1_start = id_primary_start + 4000h.

  Thereafter, when ROHC compression is performed on the RTP session of the context ID, control is performed so that the IP-ID is rewritten from id_cid1_start to a number id_cid1_current that changes in sequence. In this example, up to three contexts can be created, the second context is controlled to start from id_cid2_start with id_primary_start 8000h and id_cid3_start with id_primary_start plus C000h .

Thereafter, this operation is continued until the original IP-ID (first identification number) and each id_cid_current (second identification number) match or a new context is generated. After that, when the original IP-ID and each id_cid_current match or a new context is generated, each new id_cid_current is derived from the current id_primary_start, and the IP-ID matches for a while and there is a gap in the IP-ID. Control so as not to occur.
Id_primary_current is followed by id_cid_current at a faster speed than id_cid_current by being numbered consecutively by ICMP, UDP, and TCP for the convenience of the OS of the client PC 13. Until it is caught up, id_cid_current can be changed to be continuous.

  FIG. 5 is a flowchart showing a flow of transmission processing by the wireless terminal device according to the present invention. As shown in FIG. 5, when there is reception from the client PC 13, first, a PPP packet is constructed from the PPPoE packet (step S101). Thereafter, it is determined whether or not the configured PPP packet is a ROHC compression compatible packet (step S102). If the result of the determination is a ROHC compression compatible packet (yes), the PPP protocol type is changed to ROHC (step S103). .

  Next, it is determined whether or not the context is new (step S104). If it is determined that the context is not a new context (no), id_cid_current of the context ID is incremented (step S105). After that, it is determined whether or not it matches with other id_cid_current or IP-ID (step S106). If it does not match (no), the IP-ID is rewritten with id_cid_current (step S107).

On the other hand, if it is a new context (yes) in step S104 and if it matches (yes) in step S106, id_cid_start is recalculated from the current id_primary_current (step S108). After recalculation, the IP-ID is rewritten with id_cid_current (step S107).
After rewriting the IP-ID with id_cid_current, ROHC compression processing is performed (step S109), and after the ROHC compression processing, the PPP packet subjected to the ROHC compression processing is stored in the transmission buffer 19 (step S110). If it is determined in step S102 that the packet is not a ROHC compression compatible packet (no), the PPP protocol type remains IP (step S111), and the PPP packet is stored in the transmission buffer 19 (step S110).

Thereafter, transmission processing by the wireless communication unit 18 is performed.
FIG. 6 shows a case where the user of the wireless terminal device 10 performs a switching operation using the changeover switch 34. When the changeover switch 34 is on (ON), a process of rewriting the IP-ID to a number managed for each context ID is performed.
FIG. 6 is a flowchart showing another example of the flow of transmission processing by the wireless terminal device according to the present invention. As shown in FIG. 6, when there is reception from the client PC 13, first, a PPP packet is formed from the PPPoE packet (step S201). Thereafter, it is determined whether or not the configured PPP packet is a ROHC compression compatible packet (step S202). If the result of the determination is a ROHC compression compatible packet (yes), the PPP protocol type is changed to ROHC (step S203). .

  Next, it is determined whether or not the changeover switch 34 is on (step S204). If the changeover switch 34 is on (yes), it is determined whether or not it is a new context (step S205) and it is not a new context (no). In this case, id_cid_current of the context ID is incremented (step S206). After that, it is determined whether or not it matches with other id_cid_current or IP-ID (step S207). If it does not match (no), the IP-ID is rewritten with id_cid_current (step S208).

On the other hand, if it is a new context (yes) in step S205 and if it matches (yes) in step S207, id_cid_start is recalculated from the current id_primary_current (step S209). After recalculation, the IP-ID is rewritten with id_cid_current (step S208).
After rewriting the IP-ID with id_cid_current, ROHC compression processing is performed (step S210), and after the ROHC compression processing, the PPP packet subjected to the ROHC compression processing is stored in the transmission buffer 19 (step S211). If it is determined in step S202 that the packet is not a ROHC compression compatible packet (no), the PPP protocol type remains IP (step S212), and the PPP packet is stored in the transmission buffer 19 (step S211).

Thereafter, transmission processing by the wireless communication unit 18 is performed.
As described above, the transmission device according to the present invention provides a packet acquisition means for sequentially acquiring packets to be transmitted in a transmission device that sequentially assigns a first identification number to each packet to be transmitted and transmits the packets to the reception device. (Client PC 13), grasping means (packet filter 27) for grasping the first compression target packet among the packets obtained by the packet obtaining means, and grasping the first compression target packet by the grasping means, A second identification number calculating means (IP-ID determining unit 32) for obtaining a second identification number obtained by adding a predetermined number to the first identification number assigned to the first compression target packet; The assigned first identification number is changed to the second identification number obtained by the second identification number calculation means, and the compression after the first compression target packet is performed. The identification number changing means (IP-ID rewriting unit 33) for sequentially assigning the second identification number to the elephant packet and the compression target packet to which the second identification number is assigned by the identification number changing means are sequentially compressed. Packet compressing means (ROHC compressing section 20) for performing the processing, and compressed packet transmitting means (wireless communication section 18) for transmitting the compressed packet to the receiving device.

  The transmission method according to the present invention includes a packet acquisition step for sequentially acquiring packets to be transmitted and a packet acquisition step in the transmission method for sequentially transmitting a first identification number for each packet to be sequentially transmitted. A first grasping step for grasping a compression target packet among the acquired packets; a second grasping step for grasping the first compression target packet among the compression target packets grasped in the first grasping step; When the first compression target packet is determined in the determination step, the first identification number assigned to the first compression target packet is added to the first identification number plus a predetermined number to obtain the second identification number. An identification number changing step for sequentially assigning the second identification number to the compression target packets after the first compression target packet, and changing the identification number Second identification numbers sequentially compress the compressed packet granted by step, and a compressed packet transmission step of transmitting.

Therefore, in a wireless (transmission) device that wirelessly transmits a transmission path of an IP packet, unnecessary change information is not sent by continuously changing the IP-ID of the RTP / UDP / IP packet intended for ROHC compression. Therefore, the bandwidth is not increased, and an optimal compression rate can be obtained in ROHC compression.
Although the present invention has been described with reference to the above-described embodiment, it is not limited to this embodiment. Therefore, what is implemented as a change aspect without deviating from the meaning of the present invention is also included.

It is explanatory drawing which shows schematic structure of the radio | wireless communications system using the radio | wireless terminal apparatus which concerns on one embodiment of this invention. It is explanatory drawing which showed the example of the protocol stack transition process at the time of the VoIP call using the radio | wireless communications system of FIG. 1 with the table | surface. It is a block diagram which shows the internal structure of the radio | wireless terminal apparatus of FIG. It is explanatory drawing showing the domain space at the time of rewriting of IP-ID by the radio | wireless terminal apparatus which concerns on this invention. It is a flowchart which shows the transmission process by the radio | wireless terminal apparatus which concerns on this invention. It is a flowchart which shows the other example of the transmission process by the radio | wireless terminal apparatus which concerns on this invention.

Explanation of symbols

10 wireless terminal device 11 wireless communication system 12 wireless base station 13 client PC
14 Voice Communication Device 15 SIP Server 16 Opposite SIP Phone 17 PDSN
DESCRIPTION OF SYMBOLS 18 Wireless communication part 19 Transmission buffer 20 ROHC compression part 21 Transmission channel context holding part 22 Reception packet buffer 23 PPP determination part 24 ROHC expansion part 25 Reception channel context holding part 26 PPP packet construction part 27 Packet filter 28 PPP packet extraction process part 29 PPPoE packet construction unit 30 PC I / F unit 31 IP-ID processing unit 32 IP-ID determination unit 33 IP-ID rewriting unit 34 changeover switch

Claims (4)

In the transmission method of sequentially assigning and transmitting a first identification number that is continuous for each packet that is sequentially transmitted,
A packet acquisition step for sequentially acquiring packets to be transmitted;
A first grasping step for grasping a packet to be compressed among the packets obtained in the packet obtaining step;
A second grasping step for grasping the first packet to be compressed among the compression target packets grasped in the first grasping step;
When the first packet to be compressed is grasped in the second grasping step, the first identification number given to the first packet to be compressed is added a predetermined number to the first identification number. An identification number changing step of changing to a second identification number and sequentially assigning the second identification number to the compression target packets after the first compression target packet;
And a compressed packet transmission step of sequentially compressing and transmitting the compression target packets to which the second identification number is assigned in the identification number changing step. After the identification number changing step, a third grasping step for grasping a match between the first identification number given for each packet sequentially obtained in the packet obtaining step and the second identification number;
Based on the grasp, for the compression target packet when the first identification number and the second identification number match, the second identification number given to the compression target packet is changed to the first identification number. A second identification number changing step of changing to a third identification number obtained by adding a predetermined number to the identification number of 2, and sequentially assigning the third identification number to subsequent packets to be compressed,
The transmission method according to claim 1, wherein after the second identification number changing step, the compression target packets to which the third identification number is assigned are sequentially compressed and transmitted.   The transmission method according to claim 1 or 2, wherein the compression target packet is a user datagram protocol (User Datagram Protocol) packet. In a transmission device that sequentially assigns a first identification number that is continuous for each packet to be transmitted sequentially and transmits the packet to the reception device,
Packet acquisition means for sequentially acquiring packets to be transmitted;
Grasping means for grasping the first packet to be compressed among the packets obtained by the packet obtaining means;
A second identification for obtaining a second identification number obtained by adding a predetermined number to the first identification number assigned to the first packet to be compressed when the grasping means grasps the first packet to be compressed; Number calculating means;
The first identification number given to the first compression target packet is changed to the second identification number obtained by the second identification number calculation means, and Identification number changing means for sequentially assigning the second identification number to the packet to be compressed;
Packet compression means for sequentially compressing the compression target packets to which the second identification number is assigned by the identification number changing means;
And a compressed packet transmitting means for transmitting the packet compressed by the packet compressing means to the receiving apparatus.

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