KR101100200B1 - method of transmitting header information of packet data for point-to-multipoint multimedia multicast service - Google Patents

Abstract

The present invention relates to a method of compressing and transmitting header information of packet data. More particularly, the present invention relates to a method of transmitting packet data header information for a point-to-multimedia multicast service capable of stably transmitting packet data. It is about. The method for transmitting the header information of the packet data for the point-to-multipoint multimedia multicast service according to the present invention includes the header information of the packet data for the point-to-multipoint multimedia multicast service. A method of compressing and transmitting a data, the method comprising: transmitting a packet for compressing the header information and identifier information indicating a type of the packet to a lower layer of a communication system; And transmitting the entire header packet including all the context information for restoring the header information to the lower layer when receiving the information about the transmission failure of the packet from the lower layer. It is done. According to the present invention, even when the context update packet is discarded in the RLC layer of the transmitting side during the U-mode operation of the ROHC, the context does not need to wait until the transmitting side transitions the state of the ROHC compressor to the entire context forming state. (context) can be updated normally.

 MBMS, ROCH, Context, Discard, Compressed

Description

Method of transmitting header information of packet data for point-to-multipoint multimedia multicast service}

1 is a conceptual diagram illustrating a network structure of a UMTS to which the prior art and the present invention are applied.

2 is a conceptual diagram illustrating a structure of a terminal and a UTRAN based on the 3GPP radio access network standard.

3 is a conceptual diagram illustrating a mapping relationship between a control channel and a data channel for an MBMS.

Fig. 4 is a conceptual diagram showing the state and transition of the compressor of the transmitting side ROHC U-mode.

5 is a flowchart illustrating a process of transmitting an entire header packet according to an exemplary embodiment of the present invention.

6 is a flowchart illustrating a process of transmitting a compressed header packet according to an exemplary embodiment of the present invention.

The present invention relates to a method of compressing and transmitting header information of data, and more particularly, to a method of transmitting header information of packet data for a point-to-multimedia multicast service capable of stably transmitting data. will be.

1 is a diagram illustrating a network structure of a UMTS (Universal Mobile Telecommunications System) to which the prior art and the present invention are applied. The UMTS system is largely composed of a user equipment (abbreviated as UE), a UTMS radio access network (hereinafter referred to as a UMTS Terrestrial Radio Access Network (hereinafter referred to as UTRAN)), and a core network (hereinafter referred to as CN). UTRAN consists of one or more Radio Network Sub-systems (hereinafter referred to as RNS), and each RNS is managed by one Radio Network Controller (hereinafter referred to as RNC) and this RNC. It consists of one or more base stations (hereinafter referred to as Node B). One or more cells exist in one Node B.

FIG. 2 illustrates a structure of a radio interface protocol between a terminal and a UTRAN (UMTS Terrestrial Radio Access Network) based on the 3GPP radio access network standard. The wireless interface protocol of FIG. 2 consists of a physical layer, a data link layer, and a network layer horizontally, and a user plane for transmitting data information vertically. And Control Plane for Signaling. The protocol layers of FIG. 2 are based on the lower three layers of the Open System Interconnection (OSI) reference model, which are well known in communication systems, and include L1 (first layer), L2 (second layer), and L3 (first layer). Three layers).

Hereinafter, each layer of FIG. 2 will be described. The physical layer, which is the first layer, provides an information transfer service to an upper layer by using a physical channel. The physical layer is connected to the upper medium access control layer through a transport channel, and data between the medium access control layer and the physical layer moves through the transport channel. Then, data is moved between different physical layers, that is, between physical layers of a transmitting side and a receiving side through physical channels.

Medium access control (hereinafter referred to as MAC) of the second layer provides a service to a radio link control layer, which is a higher layer, through a logical channel. The radio link control (hereinafter referred to as RLC) layer of the second layer supports reliable data transmission, and the RLC service data unit (hereinafter referred to as SDU) from the upper layer. Segmentation and Concatenation can be performed. Let's take a closer look at the RLC layer. The RLC layer has three modes according to a function to be performed, and each of them is a transparent mode, an unacknowledged mode, and an acknowledgment mode. One of the main functions of the RLC layer is the SDU discard function. This is a function that the sender RLC entity discards old RLC SDUs among SDUs stored in order to prevent the RLC buffer from being overloaded, and plays an important role in ensuring the QoS of the radio bearer service provided by the RLC layer. There is a method by a timer and a retransmission limit. Both methods can be used in the transparent mode and the response mode in the RLC layer.

First, when the RLC layer operates in the transparent mode, no header information is added to the RLC SDU from the upper layer, and the data is transmitted to the receiver in the form of an RLC PDU. At this time, the division and reassembly of the RLC SDU is determined whether to use the radio carrier. It consists of a sending transparent mode RLC entity and a receiving transparent mode RLC entity to transmit data in one direction. Therefore, in case of wishing to transmit data in both directions, the UE and the UTRAN must be provided with a transparent side RLC entity and a transparent side RLC entity.

Second, header information is added to the RLC SDU from the upper level, and the data is transmitted to the receiver in the form of RLC PDU. However, even if the transmission of the RLC PDU fails, retransmission is not supported. Therefore, even if data is lost or a problem occurs during transmission, the receiving side does not require retransmission and discards related data. Even in the non-response mode, the transmitting side non-response mode RLC entity transmits data in one direction to the receiving side non-response mode RLC entity. Therefore, in case of data transmission in both directions, the UE and the UTRAN are provided with a transmitting non-responsive mode RLC entity and a receiving non-responsive mode RLC entity, respectively.

Finally, when the RLC layer operates in the response mode, header information is added to the RLC SDU from the upper layer and transmitted to the receiver in the form of an RLC PDU, and retransmission is supported in case of a packet transmission failure. That is, the transmitting side RLC layer receives status information from the receiving side RLC layer to determine whether the packet is successfully transmitted, and retransmits the RLC PDU requiring retransmission. In the response mode, a response mode RLC entity including a transmitting part and a receiving part exists in the terminal and the UTRAN, respectively, to enable bidirectional communication.

The radio resource control layer (hereinafter abbreviated as RRC) layer located at the bottom of the third layer is defined only in the control plane, and the configuration and resetting of radio bearers (abbreviated as RB) are performed. It is responsible for the control of logical channels, transport channels and physical channels in relation to configuration and release. In this case, the RB refers to a service provided by the second layer for data transmission between the UE and the UTRAN. In general, the RB is configured to define characteristics of a protocol layer and a channel necessary to provide a specific service. The process of setting specific parameters and operation methods.

Hereinafter, a multimedia broadcast / multicast service (hereinafter, abbreviated as MBMS) will be described in detail. MBMS refers to a method of providing a streaming or background service to a plurality of terminals using a downlink-only MBMS bearer service. One MBMS service is composed of one or more sessions, and MBMS data is transmitted to the plurality of terminals through the MBMS bearer service only while the session is ongoing.

The UTRAN provides a MBMS bearer service to the terminal using a radio bearer. Types of radio bearers used by UTRAN include point-to-point radio bearers and point-to-multipoint radio bearers. Here, the point-to-point radio bearer is a bi-directional RB, a logical channel dedicated traffic channel (DTCH) and transport channel dedicated channel (DCH), physical channel dedicated physical channel (DPCH), or physical channel SCCPCH (Secondary Common) Control Physical Channel). In addition, the point-to-multiple radio bearer is a unidirectional directional downlink RB, and as shown in FIG. 3, a logical channel MTCH (MBMS Traffic Channel), a transport channel FACH (Forward Access Channel), and a physical channel SCCPCH.

The logical channel MTCH is configured for each MBMS service provided to one cell and is used for transmitting user plane data of a specific MBMS service to a plurality of terminals. That is, the data of the MBMS service is configured in a format suitable for the entity in the non-response mode RLC entity, then transferred to the MAC layer through the logical channel MTCH, and then transmitted to the receiver.

As shown in FIG. 3, the logical channel MCMS (MBMS Control Channel) is a point-to-multipoint downlink channel used to transmit control information related to MBMS. The logical channel MCCH is mapped to a transport channel forward access channel (FACH), and the transport channel FACH is mapped to a physical channel secondary common control physical channel (SCCPCH). Only one MCCH exists in one cell. The UTRAN providing the MBMS service transmits MCCH information to a plurality of terminals through the MCCH channel. MCCH information includes the RRC message associated with the MBMS. For example, the MCCH information includes service information for transmitting information of all MBMS services that can be serviced in the current cell, MBMS Radio Bearer Information for transmitting configuration information of a point-to-multiple radio bearer, and specific information. Access information indicating that an RRC connection is requested for the MBMS service is included. That is, the RRC message, which is a control message related to the MBMS service, is configured in a non-response mode RLC entity in a format suitable for the entity, is transmitted to the MAC layer through a logical channel MCCH, and then transmitted to the receiving side.

Hereinafter, ROHC (Robust Header Compression) among the header compression techniques in charge of the Packet Data Convergence Protocol (PDCP) layer will be described in detail. ROHC is a header compression technique generally used to reduce header information of Real-time Transport Protocol (RTP) / UDP (User Datagram Protocol) / IP (Internet Protocol) packets. ROHC is a contiguous packet belonging to one packet stream. Based on the fact that the field values of the packet headers are almost constant in, first the entire packet header field is transmitted, a context is formed using the entire packet header field, and then the packet header field Instead of transmitting the whole, only the variable fields are transmitted.

The total header size of the RTP / UDP / IP packet without header compression is 40 octets for IPv4 (IP version 4) and 60 octets for IPv6 (IP version 6), whereas the payload, which is the actual packet data part, The payload size is typically 15 to 20 octets. Therefore, it can be seen that the transmission efficiency is very low due to the problem that the header information included in transmitting this data is much larger than the data to be actually transmitted. In order to solve this problem, when using the ROCH header compression technique, the required header information size is usually only about 1 to 3 octets.

The ROHC header compression technique is largely uni-directional mode (hereinafter referred to as 'U-mode'), bi-directional optimistic mode (hereinafter referred to as 'O-mode'), and bidirectional trust mode (Bi). -directional Reliable, referred to as 'R-mode' below. In the U-mode, the sender sends the real-time packet in one direction to the receiver. In the O-mode or R-mode, the sender sends the real-time packet to the receiver and the receiver transmits the transmission status information to the sender. Do it. Accordingly, in the ROHC header compression method of the O-mode and R-mode, the transmitting side receives the ROHC header compression state information (ACK or NACK) from the receiving side in the reverse direction as well as transmitting the header compression packet of the real time data to the receiving side. Controls header compression packet transmission. The ROHC header compression state information transmitted from the receiving side to the transmitting side varies depending on the mode.In the O-mode, the NACK-related information is mainly sent to increase the compression efficiency, and the R-mode uses more stringent logic. It is to support ROHC header compression technique using ROHC header compression state information.

Looking more closely at the U-mode of the ROHC header compression technique, the compressor has three states: full context, dynamic context, and full context. The types of compression header packets that can be transmitted for each state are different, and the operation method is also different. First, the structure of the context is composed of a static context and a dynamic context.

Fig. 4 is a conceptual diagram showing the state and transition of the compressor of the transmitting side ROHC U-mode.

As can be seen in Figure 4, looking at each state in detail, the entire context formation state means that the entire context is not formed, or the entire context is completely damaged and must be reconstructed. The dynamic context formation state means that the dynamic context part of the entire context is damaged and must be reconstructed, and the entire context complete state literally means the entire context without damage. Each state will timeout every cycle and transition to another state. At this time, each cycle is different. For example, the transition period from the full context state to the full context state is much greater than the transition period from the full context state to the dynamic context formation state.

The packet transmitted by ROHC header compression technique is the total header packet and the static contextual packet transmitted in the global contextual form, the dynamic contextual packet transmitted in the dynamic contextual state, and the compression sent in the full contextual state according to each state. Composed of a header packet, and when the sender transmits the entire header packet, the static contextual packet, or the dynamic contextual packet, the receiver receives the packet and successfully forms and updates the context. Although the header packet can be successfully recovered, if the packet is not successfully received, the context cannot be formed and updated normally, so that the compressed header packet transmitted later cannot be recovered. Therefore, since the sender cannot receive the header compression state information from the receiver, such as O-mode or R-mode, the sender sends the packet several times when transmitting the entire context packet, the static contextual packet, or the dynamic contextual packet. By performing the state transition after the transmission, the receiving side can form and update the context normally so that the compressed header packet can be restored. Here, the context context packet is defined as the context context packet, the context context packet, the context context packet, and the context header packet to update the context.

The prior art described above has the following problems. In the prior art, when the ROHC header compression technique is used in the MBMS, it is defined to use the RLC UM mode and the U-mode of the ROHC due to the downlink-oriented service characteristic of the MBMS. In the RLC UM mode, there is an RLC SDU discard function to prevent the overflow of the buffer. If the context update packet is discarded at the sending RLC layer during the U-mode operation of the ROHC, the context of the receiver restorer cannot be formed or updated normally. In this case, the timeout becomes a characteristic of ROHC U-mode operation, and the transition continues from the sender to the full context form or the dynamic context form state until the entire header packet or the static context form packet or the dynamic context form packet is transmitted to the receiver side. There is a problem that the context non-update packet and the context update packet received after the discarded context update packet during the period cannot be restored normally.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to discard a RLC SDU including a context update packet at a transmitting side RLC layer in a context update packet during U-mode operation of ROHC. By passing the discard information to the header compression responsible layer in charge of ROHC, the context is normally updated as soon as possible without having to wait for the sender to transition the state of the ROHC compressor to the full or dynamic context. The present invention provides a method of transmitting header information of packet data for a point-to-multimedia multicast service.

According to a preferred embodiment of the present invention, a method of compressing and transmitting header information for a multicast or broadcast service (Multimedia Braoadcast / Multicast Service) in a wireless system and a mobile terminal by using a header compression technique will be described. do.

The method for transmitting the header information of the packet data for the point-to-multipoint multimedia multicast service according to the present invention includes the header information of the packet data for the point-to-multipoint multimedia multicast service. A method of compressing and transmitting a data, the method comprising: transmitting a packet for compressing the header information and identifier information indicating a type of the packet to a lower layer of a communication system; And transmitting the entire header packet including all the context information for restoring the header information to the lower layer when receiving the information about the transmission failure of the packet from the lower layer. It is done.

According to another aspect of the present invention, when receiving information on a packet transmission failure from the lower layer, the entire header packet including all the context information for restoring the header information may be transmitted to the lower layer. The state of the compressor is shifted to the entire context forming state irrespective of the conventional method according to the timeout. Other detailed features of the method for transmitting the header information of the packet data for the point-to-multimedia multicast service according to the present invention The context update packet includes an entire header packet including all of the context information, a static context forming packet including information about a static context in the context information, and a dynamic context among the context information. Among dynamic header forming packet including information about and compressed header packet including compressed header information. It would in any one of the compressed header packet is intended to include (Cyclic Redundancy Check) CRC.

Another detailed feature of the method for transmitting header information of packet data for a point-to-multimedia multicast service according to the present invention is that the identifier information indicates whether the context update packet is a compressed header packet, and the context update If the packet is not a compressed header packet, the identifier information includes information about the number of times the context update packet is transmitted continuously.

Another detailed feature of the method for transmitting the header information of the packet data for the point-to-multimedia multimedia multicast service according to the present invention is that the transmission failure of the context update packet is transmitted by the packet data discard function in the lower layer. It is a failure.

 Another detailed feature of the method for transmitting the header information of the packet data for the point-to-multimedia multimedia multicast service according to the present invention is the information on the context update packets discarded the information about the transmission failure of the context update packet. The information on the discarded context update packets includes information about the sequence number of discarded context update packets.

The method for transmitting the header information of the packet data for the point-to-multipoint multimedia multicast service according to the present invention includes the header information of the packet data for the point-to-multipoint multimedia multicast service. CLAIMS 1. A method for compressing and transmitting a data, comprising: receiving a context update packet for compressing the header information and identifier information indicating a type of the context update packet from an upper layer of a communication system; If there is a transmission failure of the context update packet, transmitting information on the transmission failure of the context update packet to the upper layer; And transmitting the entire header packet including all the context information for restoring the header information in the upper layer.

Still another aspect of the present invention provides a method for transmitting a context update packet discarded in a lower layer to the upper layer; The upper layer determines the type of the discarded context update packet, and transitions to the entire context forming state or the dynamic context forming state according to the result, and transmits the whole header packet or the static context forming packet in the whole context forming state. Or transmitting the dynamic context forming packet in the dynamic context forming state.

Another detailed feature of the method for transmitting header information of packet data for a point-to-multi-media multicast service according to the present invention is that the point-to-multi-media service is a Multimedia Broadcasting and Multicast Service (MBMS).

The construction, operation and other features of the present invention will become apparent from the preferred embodiments of the present invention described with reference to the accompanying drawings.

A preferred embodiment of the present invention can be described by dividing the case of transmitting the entire header packet, the static contextual type packet or the dynamic context forming packet in the PDCP layer, and the case of transmitting the context update compression header packet.

A case in which the entire header packet, the static context-forming packet or the dynamic context-forming packet is transmitted in the PDCP layer of the transmitter will be described below. In the PDCP layer, various types of packets may be transmitted as described above. Hereinafter, as a preferred embodiment, a method of transmitting packet data header information in the case of transmitting the entire header packet from the PDCP layer of the transmitting side to the RLC layer of the transmitting side will be described.

The entire header packet is transmitted from the PDCP layer of the transmitting side to the receiving side through the RLC layer of the transmitting side, and since the U-mode of ROHC is used, the transmitting side can confirm whether the entire header packet is normally received at the receiving side. none. Therefore, the entire header packet is transmitted several times in succession. When the entire header packet is transmitted to the receiving side one or more times, the receiving side may update the context. Therefore, one or more transmissions among the several times N must be successful. If all of the transmissions fail N times, the receiver cannot update the context normally. Therefore, when the transmitter becomes timeout and transitions to the full context, the entire header packet is transmitted. Should try again

The transmission failure of the entire header packet may be made by a service data unit (SDU) discard function in the transmitting RLC layer. When an RLC SDU including the entire header packet is transmitted from an upper layer of the RLC layer to the RLC layer, a timer for counting the time of staying in the RLC layer is driven for the RLC SDU, and is predetermined. When the time expires, the RLC SDU is discarded.

The PDCP layer generates indicator information indicating whether the information received in the RLC layer includes the entire header packet, the static contextual packet or the dynamic contextual packet, or the context update header packet. . For example, if '0' is stored in a specific bit of the indicator, the total header packet or static contextual packet or dynamic contextual packet is included. If '1' is stored, the context update is performed. It may mean that a compression header packet is included. In another embodiment, if a '0' is stored in a specific bit of the indicator, the entire header packet is stored; if a '1' is stored, a static context forming packet is stored; if a '2' is stored, a dynamic context forming packet is stored; When this is stored, it may mean that the context gang compression header packet is included. The entire header packet or the static contextual packet or the dynamic contextual packet is changed state after being transmitted N times consecutively in the PDCP layer, and the compressed header packet is transmitted once, so that the identifier ( indicator) Create information. The indicator information includes information about the number N of consecutive transmission of the entire header packet in the PDCP layer.

The indicator information may be included in primitive information delivered from the PDCP layer to the RLC layer. Table 1 below describes primitives between the RLC layer and higher layers. More preferably, the indicator information is included in a DiscardReq parameter included in RLC-UM-DATA-Req.primitive in RLC UM mode.

Generic name Parameters Req. Ind. Resp. Conf. RLC-UM-DATA Data, UE-ID type
indicator, DiscardReq, MUI data Not Defined MUI

The RLC layer may recognize that the entire header packet is received through the identifier information, and the PDCP layer may determine the total header packet through the information about the number of transmissions N included in the identifier information. You can see how many times the header packet is sent. If the transmission of the entire header packet fails N times in succession, the context cannot be updated normally at the receiver. Therefore, information on the failure of the transmission should be transmitted to the PDCP layer. In addition, since the failure of the transmission is caused by the SDU discard in the RLC layer, the discard information is transmitted to the PDCP layer to inform the PDCP layer that the transmission has failed.

The information about discarding includes information about service data units (SDUs) discarded at the RLC layer. In addition, the information about the service data units (SDU) is preferably information about the sequence number of the discarded SDU (sequence number). The sequence number may be transmitted to inform the PDCP layer that the transmission of the entire header packet has failed N times in succession. The method of including the information on the sequence number of the SDU in the information on the discard is not limited in kind. For example, all of the sequence numbers of discarded SDUs may be transmitted. The serial number of the discarded SDU is transmitted by transmitting only the lowest number among the number N of transmitting the entire header packet and the discarded sequence number or by transmitting only the largest number. (sequence number) can be known.

The discarding information may be included in primitive information transmitted from the RLC layer to the PDCP layer. More preferably, the discarding information is included in a message unit identifier (MUI) parameter included in RLC-UM-DATA-Req.primitive in RLC UM mode.

When the PDCP layer receives the discard information, the receiving side is in a state in which it is impossible to update the context. Thus, the PDCP layer transmits the entire header packet through the transmitting RLC layer. Send again. In other words, the state of the transmitting ROHC compressor is shifted to the entire context forming state. As a method different from the above method, even when the static context-forming packet or the dynamic context-forming packet is transmitted N times in succession, the context cannot be updated normally at the receiving side. The entire header packet is sent back to the sender RLC layer.

5 is a flowchart illustrating a process of transmitting an entire header packet according to an exemplary embodiment of the present invention. The PDCP layer on the transmitting side transmits all header packets N times in succession to the RLC layer on the transmitting side (S501). The PDCP layer may transmit identifier information together, and may transmit information on the number N of consecutive transmissions of the entire header packet through the identifier information. When the transmission side RLC layer generates an SDU discard and the transmission of the entire header packet fails N times consecutively, the transmitting RLC layer informs the transmitting side PDCP layer of the transmission failure (S502). The transmitting side PDCP layer receives the information on the transmission failure and is notified that the receiving side cannot update the context normally, and transmits the entire header packet (S503). The transmitting side RLC layer transmits the entire header packet to the receiving side to allow the receiving side to update the context normally (S504).

Hereinafter, a method of transmitting packet data header information when a context update header packet is transmitted from the PDCP layer to the RLC layer according to an embodiment of the present invention will be described. The above embodiment is applied to a case of transmitting a compression header packet including a CRC, that is, a context update compression header packet, from the PDCP layer to the RLC layer. Therefore, the receiving side receiving the context update compression header packet may update the context.

The context update compression header packet is transmitted from the PDCP layer of the transmitting side to the receiving side through the RLC layer of the transmitting side. It is also transmitted when the ROHC compressor on the transmitting side is in the full context state. If the context update header packet fails to be transmitted, the context may not be updated successfully at the receiver side and the context may be corrupted. The transmitter side transmits the entire header packet. Should be.

The transmission failure of the context update header header packet may be performed by a service data unit (SDU) discard function in the transmitting RLC layer. When an RLC SDU including the context update header packet is transmitted from an upper layer of the RLC layer to the RLC layer, a timer for counting the time of staying in the RLC layer for the RLC SDU is driven. When the predetermined time expires, the RLC SDU is discarded.

The PDCP layer generates indicator information indicating whether the information received in the RLC layer includes the entire header packet, the static contextual packet or the dynamic contextual packet, or the context update header packet. . For example, if '0' is stored in a specific bit of the indicator, the total header packet or static contextual packet or dynamic contextual packet is included. If '1' is stored, the context update is performed. It may mean that a compression header packet is included. The whole header packet or the static contextual packet or the dynamic contextual packet is transmitted N times in the PDCP layer, and the other context update header packet is transmitted once. Therefore, the identifier information is used to distinguish the two. Create

The indicator information may be included in primitive information delivered from the PDCP layer to the RLC layer. Table 2 below describes primitives between the RLC layer and higher layers. More preferably, the indicator information is included in a DiscardReq parameter included in RLC-UM-DATA-Req.primitive in RLC UM mode.

Generic name Parameters Req. Ind. Resp. Conf. RLC-UM-DATA Data, UE-ID type
indicator, DiscardReq, MUI data Not Defined MUI

The RLC layer may know that the context update header packet is received through the identifier information. If the context update header packet fails to be transmitted, the context cannot be properly updated by the receiver. Therefore, information about the failure of the context should be transmitted to the PDCP layer. In addition, since the failure of the transmission is caused by the SDU discard in the RLC layer, information about the discard is transmitted to the PDCP layer to inform the PDCP layer that the transmission has failed.

The information about discarding includes information about service data units (SDUs) discarded at the RLC layer. In addition, the information about the service data units (SDU) is preferably information about the sequence number of the discarded SDU (sequence number). The sequence number may be transmitted to inform the PDCP layer that the context update header packet transmission has failed. The method of including the information on the sequence number of the SDU in the information on the discard is not limited in kind. For example, a sequence number of discarded SDUs may be transmitted.

The discarding information may be included in primitive information transmitted from the RLC layer to the PDCP layer. More preferably, the discarding information is included in a message unit identifier (MUI) parameter included in RLC-UM-DATA-Req.primitive in RLC UM mode.

When the PDCP layer receives the discard information, the receiving side is in a state in which the context cannot be updated. Thus, the PDCP layer has a total header packet through the RLC layer of the transmitting side. Send it again. In other words, the state of the transmitting ROHC compressor is shifted to the entire context forming state.

6 is a flowchart illustrating a process of transmitting a compressed header packet according to an exemplary embodiment of the present invention. The PDCP layer on the transmitting side transmits a context update compression header packet to the RLC layer on the transmitting side (S601). The PDCP layer sends the identifier information together to indicate that the packet is a context update header packet. When the transmission side RLC layer fails to transmit the entire header packet because SDU discard occurs, the transmitting side RLC layer notifies the transmitting side PDCP layer (S602). The transmitting side PDCP layer receives the information about the transmission failure and is informed that the receiving side cannot update the context normally, and transmits the entire header packet (S603). The transmitting side RLC layer transmits the entire header packet to the receiving side so that the receiving side can update the context normally (S604).

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit and scope of the present invention. Accordingly, the scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

The effects of the method for transmitting the header information of the packet data for the point-to-multimedia multicast service according to the present invention as described above are as follows. Even if the context update packet is discarded at the sender's RLC layer during the U-mode operation of ROHC, the context is normally updated as soon as possible without waiting for the sender to transition the state of the ROHC compressor to the full context. Can be.

Claims (18)

In a method for compressing and transmitting header information of packet data in a Packet Data Convergence Protocol (PDCP) layer for a point-to-multipoint multimedia multicast service, Delivering a context update packet and identifier information indicating a type of the context update packet to a lower layer of the communication system; And When receiving the information on the transmission failure of the context update packet from the lower layer, transmitting the entire header packet including all the context information for restoring the header information to the lower layer, The identifier information indicates whether the context update packet is a compressed header packet. When the context update packet is not a compressed header packet, the identifier information includes information about the number of times the context update packet is transmitted. Method for transmitting the header information of the packet data for the point-to-multimedia multimedia multicast service, characterized in that. The method of claim 1, The context update packet includes an entire header packet including all of the context information, a static context forming packet including information about a static context in the context information, and a dynamic context among the context information. Method for transmitting the header information of the packet data for a point-to-multimedia multimedia multicast service, characterized in that any one of a dynamic context-forming packet comprising information on and a compressed header packet comprising compressed header information. 3. The method of claim 2, The compressed header packet includes a cyclic redundancy check (CRC) for transmitting header information of packet data for a point-to-multimedia multimedia multicast service. delete delete The method of claim 1, The transmission failure of the context update packet is a transmission failure due to a packet data discard function in the lower layer. The method of claim 1, And the information on the transmission failure of the context update packet is information about discarded context update packets. The method of claim 7, wherein The information on the discarded context update packets includes information on the sequence number of the discarded packets. The header information of the packet data for the point-to-multimedia multicast service is transmitted. Way. The method of claim 1, The point-to-multipoint multimedia service is a multimedia broadcasting or multicast service (MBMS), characterized in that for transmitting the header information of the packet data for the point-to-multimedia multicast service. In a method for compressing and transmitting header information of packet data in a Packet Data Convergence Protocol (PDCP) layer for a point-to-multipoint multimedia multicast service, Receiving a context update packet and identifier information indicating a type of the context update packet from an upper layer of the communication system; Transmitting information regarding a transmission failure of the context update packet when there is a transmission failure of the packet; And Receiving an entire header packet including all context information for restoring the header information from the upper layer; The identifier information indicates whether the context update packet is a compressed header packet. When the context update packet is not a compressed header packet, the identifier information includes header information of packet data for a point-to-multimedia multicast service, wherein the identifier information includes information about the number of times the context update packet is transmitted. Way. The method of claim 10, The context update packet includes an entire header packet including all of the context information, a static context forming packet including information about a static context in the context information, and a dynamic context among the context information. Method for transmitting the header information of the packet data for a point-to-multimedia multimedia multicast service, characterized in that any one of a dynamic context-forming packet comprising information on and a compressed header packet comprising compressed header information. The method of claim 11, The compressed header packet includes a cyclic redundancy check (CRC) for transmitting header information of packet data for a point-to-multimedia multimedia multicast service. delete delete The method of claim 10, The transmission failure of the context update packet is a transmission failure due to a packet data discard function. The method for transmitting header information of packet data for a point-to-multimedia multimedia multicast service. The method of claim 10, And the information on the transmission failure of the context update packet is information about discarded context update packets. The method of claim 16, The information on the discarded context update packets includes information on the sequence number of the discarded packets. The header information of the packet data for the point-to-multimedia multicast service is transmitted. Way. The method of claim 10, The point-to-multipoint multimedia service is a multimedia broadcasting or multicast service (MBMS), characterized in that for transmitting the header information of the packet data for the point-to-multimedia multicast service.

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