KR100379404B1 - header data format in cable modem and suppressed method of the same - Google Patents

Abstract

The present invention provides a header data structure and a compression method of a cable modem for transmitting only PHSF (Payload Header Suppression Field) TLV information to a receiver, and a payload selected using PHSM TLV information at a transmitter. Compressing each byte of the header and transmitting a packet including a PHSF composed of only the compressed byte stream to a receiving side, obtaining SID and PHSI information from the packet data transmitted at the transmitting side, and used for compression. Detecting PHSM, PHSF, and PHSS TLV information; comparing the number of bytes of the detected PHSS with the number of bytes in the actual PHSF information; and if the comparison result is different, according to each bit value of the PHSM. If 1, the byte value in the detected PHSF is read in order. If the value is 0, the byte value of the corresponding position is read from the transmitted payload header. Come into yirueojim including the step of: reconfiguring the payload header, and at least the size of the PHS-related data to be transmitted in the Configuration file or a MAC management message can maximize the efficiency of the cable network.

Description

Header data format in cable modem and suppressed method of the same}

The present invention relates to cable network communication, and more particularly, to a header data structure and a compression method for improving data transmission efficiency of a cable modem.

Cable network communication has been widely used worldwide as media providing various multimedia services such as analog signals, data signals, voice and video.

The cable network communication is a cable modem terminal system connected to a wide area network for transmitting and receiving data with a cable modem (CM) 20, which greatly helps to transmit and receive data from a user side, as shown in FIG. 1. (Cable Modem Terminal System: CMTS) (10).

The CMTS 10 is included in a head end portion and receives a signal (upstream) transmitted from the cable modem 20 of each household, and receives a data signal (downstream) to the cable modem 20 of each household. Will be sent.

In the downstream signal transmitted from the CMTS 10, several cable modems 20 are commonly used to transmit media access control (MAC) management messages for controlling cable media. Using this information, the cable modem 20 obtains information about how it should be operated.

As such, voice data among data exchanged between the CM 20 and the CMTS 10 may be implemented in the format shown in FIG. 2 (G.711 VoIP Traffic).

In FIG. 2, FGPS is information required for a PHY layer, and is a MAC (Media Access Control) header from MAC OH (Over Head) to HCS (Header Check Sum), which is added in the MAC layer along with an Ethernet field. The remaining fields are information added from the upper layer above it.

As can be seen in FIG. 2, the inefficiency of the voice data packet can be confirmed by comparing the size of the voice byte field and the size of the remaining header field.

That is, the sum of the total headers is 53 bytes, and the voice data field is at most 160 bytes. Therefore, the byte ratio of the entire header to voice data has a ratio of 53: 160, about 1: 3.

It can be seen that the header occupies about 25% of all packets except FGPS.

In order to improve such inefficiency, payload header compression is used, which compresses and compresses a portion transmitted in every packet without changing continuously among the values of the payload header portion (Ethernet to RTP field) of a transmitted data packet. It is a method of transmitting a packet having a payload header.

Payload Header Suppression Mask (PHSM) Type-Length-Value (TLV), which is the location information of the portion to be compressed, to recover the compressed packet, and Payload Header Suppression Field (PHSF) TLV, which is the actual value of the compressed field, The Payload Header Suppression Index (PHSI) TLV, which is the index value for the information, and the Payload Header Suppression Size (PHSS) TLV, which is the total payload header size value to be compressed, must be transmitted to the CM in a configuration file or other method.

And, by providing the PHSV (Payload Header Suppression Verify) TLV information by comparing the PHSF and the field to be actually compressed to determine whether the PHSF is configured correctly.

The PHS TLV information is transmitted to the CM 20 by a configuration file or a dynamic service addition / replacement / deletion MAC management message in a format as shown in FIG. 5.

Such a conventional payload header compression method will be described below with reference to FIGS. 3A to 3B.

First, referring to FIG. 3A, when a packet arrives at the transmitter (S10), the packet is classified by type, and the PHSF, PHSI, PHSM, PHSS, and PHSV are searched through the header of each classified packet ( S20).

Then, whether or not to compress each byte of the payload header is determined according to the value of PHSV among the searched PHS data formats (S30).

That is, when the PHSV value is on, it is determined that compression is performed, and when it is off, it is determined that compression is not performed.

Accordingly, when the PHSV value is on, a portion to be compressed and a portion to be transmitted as it is is selected with the PHSF information (S40).

When a compression execution command is applied (S50), compression is performed using a PHSF value indicating a bit to be compressed among PHSF information data of each byte, and a PHSI having an index value for each PHS data format is added to the compressed payload header. To generate (S60).

Subsequently, the packet including the generated compressed payload header is transmitted to the receiving side (S70).

Next, referring to FIG. 3B, when a packet including a compressed payload header transmitted from a transmitter arrives (S80), the receiver has index values for SIDs and PHS data formats included in all packets. The PHSI is detected (S90).

Then, the PHSF, PHSM, and PHSS values are searched through the detected PHSI information (S100).

Subsequently, the cable modem 20 reconstructs the header using the retrieved PHS data format (S110), and then transmits the reconstructed packet to the user (S120).

The operation principle of the PHS using the payload header compression method will be described in detail with reference to FIG. 4 as follows.

First, if each bit in the PHSM Value field is set to 1 at the sender, data (A, C, E bytes) at the position is not transmitted. If the bit in the PHSM Value field is 0, The data (B, D bytes) at the position is transferred as it is.

In this case, the value of the payload header compressed field size (PHSS) TLV is 5 bytes in which both the compressed portion and the uncompressed portion are added together.

Therefore, the data packet actually transmitted through the cable network is compressed 3 bytes out of 5 bytes and only the remaining 2 bytes are transmitted, the receiver is to restore the original data using the PHSMTLV and PHSF TLV information.

As shown in FIG. 4, the PHSF TLV information transmits not only the information of the compressed portion but also the information of the uncompressed portion to the receiver. Accordingly, the actual number of bytes of the compressed data is 3 bytes, but as much as 2 bytes of uncompressed information is also included in the PHSF information, and a total of 5 bytes are transmitted to the cable modem 20.

Accordingly, the present invention has been made to solve the above problems, and in the method of efficiently transmitting data using the payload header compression method, only PHSF (Payload Header Suppression Field) TLV information is actually required to the CM. By transmitting, the purpose is to maximize the efficiency of the cable network by minimizing the size of the PHS-related data to be transmitted in the configuration file or MAC management message.

1 illustrates a cable modem network according to the prior art.

2 illustrates a format of a voice data packet according to the prior art.

3 is a flowchart illustrating the operation of payload header compression according to the prior art.

4 is a view illustrating an operation principle of payload header compression according to the prior art.

5 is a diagram illustrating an information data format of payload header compression according to the prior art.

6 illustrates an information data format of payload header compression according to the present invention.

7 illustrates an operation principle of payload header compression according to the present invention.

8 is a view comparing the conventional method and the payload header compression method of the present invention.

9 is a flowchart illustrating the operation of payload header compression according to the present invention.

* Explanation of symbols for main parts of the drawings

10: CMTS 20: Cable Modem (CM)

A feature of the header data structure and compression method of a cable modem according to the present invention for achieving the above object is a header data structure of a cable modem used for transmission and reception of header data on a cable network, wherein the header data structure is a compressed field. PHSF having only byte strings sequentially compressed to the actual value of F, PHSM having position information of the portion to be compressed to recover the compressed packet, PHSS having the total payload header size value being compressed, and the PHSF and actual And a PHSI having an index value for the PHSF, PHSM, PHSS, and PHSV information by comparing a field to be compressed and confirming whether the PHSF is properly configured.

A feature of the method for compressing header data of a cable modem according to the present invention for achieving the above object includes a PHSF configured to compress each byte of a payload header selected using PHSM TLV information at a transmitting side and consist of only a compressed byte stream. A first step of transmitting a packet to the receiving side, and a second step of obtaining SID and PHSI information from the packet data transmitted from the transmitting side and detecting PHSM, PHSF, and PHSS TLV information used for compression; And a third step of comparing the number of bytes of the detected PHSS and the number of bytes in the actual PHSF information; and if the comparison result is different, if the value is 1 according to each bit value of the PHSM, the byte value in the detected PHSF is determined. Including a fourth step of reading in sequence, and if 0, reconstructing the payload header by reading the byte value at that position in the transmitted payload header It is done.

If the comparison result of step 3 is the same, the value of PHSF information byte of the bit position is read according to each bit value of PHSM. If the bit value is 0, the byte value of the position is read from the transmitted payload header. There is another feature, which further comprises reading and reconstructing the payload header.

The packet transmitted in the first step removes the PHSF information byte value at the position where the bit value of the PHSM is 0, and transmits a packet including the PHSF sequentially configured with only the PHSF information byte value at the position 1 to the receiving side. There are other features.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

A preferred embodiment of the header data structure and the compression method of the cable modem according to the present invention will be described with reference to the accompanying drawings.

6 is a diagram illustrating a PHS information data format according to the present invention, in which a transmitting party compressing data transmits PHS TLV information such as FIG. 6 to a receiving side in the form of a configuration file or a MAC management message.

In this case, the transmitting side and the receiving side are CM in the upstream direction, the CMTS is the receiving side, the downstream side is the CMTS, and the receiving side is CMTS.

As shown in FIG. 6, the PHS information data format according to the present invention differs from the conventional technology in that the value field value of the Payload Header Suppression Field (PHSF) TLV is composed of only payload header data actually compressed among the PHS TLV information. will be.

That is, in the prior art, even if the compressed byte is the first and the last two bytes of the total n bytes as shown in A) of FIG. 8, the value field data of the PHSF TLV delivers all n bytes of information to the cable modem However, in the present invention, as shown in B) of FIG. 8, only data of an actual compressed location may be transmitted to the cable modem through the value field of PHSF.

7 and 9 illustrate a method of recovering compressed data by a cable modem when transmitting to a cable modem through a PHSF TLV configured only with information that is actually compressed. The operation thereof is as follows.

First, the transmitting side (CMTS) transfers the PHS information of each service in the configuration file to the receiving side (CM) in the form of TLV (Type-Length-Value) as shown in FIG. The cable modem receiving this information checks whether a PHS packet is being received (S130).

At this time, the transmitting side selects the portion to be compressed and the portion to be transmitted as it is by using the PHSM TLV information before transmitting to the receiving side. Each bit of the value field of the PHSM TLV determines whether or not each byte of the payload header is compressed.

That is, if the bit in the PHSM information is set to 1, the data of this bit position is compressed and inserted into the packet and transmitted to the receiving side. If the bit is 0, the data of this bit position is inserted into the packet without compression. Send to the receiver.

Packet data compressed and transmitted in this manner is received by the cable modem.

The cable modem obtains SID and Payload Header Suppression Index (PHSI) information from the received packet data (S140) and finds PHSM, PHSF, and PHSS TLV information used for compression (S150).

The cable modem compares the number of bytes of the detected PHSS with the number of bytes in the actual PHSF information. If the values are different, the cable modem judges that the present invention has PHSF TLV information proposed by the present invention. It is determined that the method proposed in has PHSF TLV information (S160).

Therefore, when determining that the cable modem uses the PHSF information proposed by the present invention, the cable modem checks each bit value of the PHSM as shown in FIG. If the bit value is 0, the byte value is read and reconstructed from the transmitted payload header without referring to the byte value in the PHSF information (S180).

At this time, the PHSF TVL information received by the receiver is continuously configured with only the bit value when the PHSM bit value is one. Therefore, each byte position of the original PHSF information before transmitting at the transmitting side has a different position value from each byte position of the PHSF information after receiving at the receiving side.

Accordingly, the present invention does not reconstruct using the byte position value of the received payload header value, and reconfigures the byte position in the conventional device by sequentially reading the byte value of the received PHSF information when the bit value of the PHSM is 1. It is compatible with no device to specify.

If it is determined that the cable modem uses the PHSF information proposed in the prior art, the cable modem checks each bit value of the PHSM as shown in FIG. 4, and if the bit value is 1, reads the PHSF information byte value of the bit position. If the bit value is 0, the byte value is read and reconstructed from the transmitted payload header without referring to the byte value in the PHSF information (S170).

The packet reconstructed in this manner is delivered to the user (S190).

As described above, the present invention minimizes the configuration file download time by minimizing the size of the configuration file and the size of the MAC management message by configuring only the compressed byte information as shown in FIG. 6 without using PHSF TLV information as shown in FIG. In addition, the PHS TLV government in the MAC management message can be optimized to effectively use the bandwidth of the cable network.

The header data structure and compression method of the cable modem according to the present invention as described above has the following effects.

First, in case of PHS, the size of PHSF TLV information can be optimized to minimize the size of configuration file or MAC management message.

Second, it can minimize the time required when the cable modem downloads the configuration file, and it can minimize the packet size when sending and receiving MAC management messages between the CMTS and the CM to optimize the bandwidth of the cable network. Can be.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (4)

In the header data structure of a cable modem used to transmit and receive header data over a cable network, The header data structure includes a PHSF having only byte strings sequentially compressed to actual values of a compressed field; PHSM having position information of the portion to be compressed to restore the compressed packet, PHSS with the total payload header size value being compressed, A PHSV comparing the PHSF with a field to be actually compressed to confirm that the PHSF is configured correctly; And a PHSI having an index value for the PHSF, PHSM, PHSS, and PHSV information. A first step of compressing each byte of the selected payload header using PHSM TLV information at the transmitting side and transmitting a packet including a PHSF composed of only the compressed byte stream to the receiving side; A second step of obtaining SID and PHSI information from the packet data transmitted from the transmitting side and detecting PHSM, PHSF, and PHSS TLV information used for compression; A third step of comparing the number of bytes of the detected PHSS with the number of bytes in actual PHSF information; If the comparison result is different, if the value is 1 according to each bit value of PHSM, the byte value in the detected PHSF is read in order, and if the value is 0, the byte value of the corresponding position is read from the transmitted payload header to reconstruct the payload header. The header data compression method of the cable modem, characterized by comprising a fourth step. The method of claim 2, If the comparison result of step 3 is the same, the value of PHSF information byte of the bit position is read according to each bit value of PHSM. If the bit value is 0, the byte value of the position is read from the transmitted payload header. And reconfiguring the payload header by reading the header data compression method of the cable modem. The method of claim 2, The packet transmitted in the first step removes the PHSF information byte value at the position where the bit value of the PHSM is 0, and transmits a packet including the PHSF sequentially configured with only the PHSF information byte value at the position 1 to the receiver. A header modem data compression method for a cable modem.