KR100736484B1 - Method of managing buffer for supporting HSDPA system dynamic in mobile system - Google Patents

Abstract

The present invention relates to buffer management of a multiple access control (MAC) layer and a radio link control layer (RLC) in a 3GPP asynchronous (UMTS) mobile communication High Speed Downlink Packet Acsess (HSDPA) system. In particular, a MAC buffer and an RLC buffer coexist. The present invention relates to a buffer management method for supporting an HSDPA system of a mobile communication in which an HSDPA system can coexist with an existing third generation wireless communication system through an efficient buffer management method.

According to another aspect of the present invention, there is provided a buffer management method for supporting a HSDPA system of a mobile communication, the method including: adding a MAC buffer, which is a data buffer, by extending a MAC layer; Transmitting and storing data to the Mac buffer at an upper RLC layer; Updating data retransmission and buffer status for efficient management of the RLC buffer and the Mac buffer; And providing additional data according to the buffer status of the MAC layer.

Description

Buffer management method for supporting HSDPA system of mobile communication {Method of managing buffer for supporting HSDPA system dynamic in mobile system}             

1 is a block diagram of a 3GPP UMTS (asynchronous) system to which the prior art and the present invention are applied.

2 is a structure of a radio interface protocol according to the 3GPP radio access network standards

3 shows an example of a protocol hierarchy for each radio access network component according to 3GPP standards

4 is a structure of an RLC layer and a MAC layer of the UTRAN side

5 is a structure of the RLC buffer and the status indicator of the RLC buffer

6 is a MAC layer structure of the HSDPA system

7 is a protocol hierarchy for each component of a wireless access network supporting the HSDPA system

8 is MAC buffer structure and MAC buffer status indicator of the HSDPA system

9 is an RLC buffer structure and an RLC buffer state indicator of an HSDPA system.

10 is a flowchart of buffer management for supporting the HSDPA system of the present invention.

11 is a flowchart for requesting supply of additional RLC PDUs to the RLC layer (when triggered by the MAC layer).

12 is a flowchart for supplying additional RLC PDUs to the MAC buffer (when triggered by the RLC layer)

The present invention relates to buffer management of a multiple access control (MAC) layer and a radio link control layer (RLC) in a 3GPP asynchronous (UMTS) mobile communication High Speed Downlink Packet Acsess (HSDPA) system. In particular, a MAC buffer and an RLC buffer coexist. The present invention relates to a buffer management method for supporting an HSDPA system of a mobile communication in which an HSDPA system can coexist with an existing third generation wireless communication system through an efficient buffer management method.

In more detail, the MAC layer is extended to add a MAC buffer, which is a data buffer, to the Node B of the RNC, and data is transferred to the Mac buffer from the upper RLC layer to the Mac buffer in the form of a Mac PDU. In order to efficiently manage the RLC buffer and the Mac buffer, data retransmission and buffer status are updated between the RLC layer and the MAC layer so that additional RLC PDUs can be provided by the MAC layer request or the RLC layer according to the buffer state of the MAC layer. The present invention relates to a buffer management method for supporting an HSDPA system.

In general, ARIB in Japan, ETSI in Europe, T1 in USA, TTA in Korea, and TTC in Japan have been developed through the project called Third Generation Partnership Project (hereinafter abbreviated as 3GPP). A third generation mobile communication system that can provide such multimedia services in a wireless environment is under development.

Next-generation mobile communication technology through 3GPP aims to provide high-speed data service by introducing and developing management technique of GSM (Global System for Mobile Communications) network and Code Division Multiple Access (CDMA) technology. I am doing it.

3GPP supports the activities of five Technical Specification Groups (hereinafter abbreviated as TSG) for fast and efficient project operation and technology development, and each TSG has a set of standards related to the assigned area. Responsible for development, approval, and management. Among them, the Radio Access Network (RAN) group aims to define a new radio access network in the third generation mobile communication system, and abbreviated as a mobile station and a Universal Mobile Telecommunications Network Terrestrial Radio Access Network (hereinafter referred to as UTRAN). Develop specifications for the functionality, requirements, and interfaces of

The TSG-RAN Group is again composed of a Plenary Group and four Working Groups. Working Group 1 (WG1) develops standards for the Physical Layer (WG1), while the second Working Group (WG2) works with the Data Link Layer (2nd Layer) and Network Layer (WG2). Role of the third tier). In addition, the third operation group defines standards for interfaces between base stations, radio network controllers (hereinafter, abbreviated as RNCs), and core networks in the UTRAN, and the fourth operation group defines radio link performance. Discuss requirements and requirements for radio resource management.

1 is a block diagram of a 3GPP UMTS (asynchronous) system to which the prior art and the present invention are applied.                         

For example, the user equipment (UE) 10 may be a mobile station (MS) of mobile communication, a base station 20a (Node B), a control station 20b (RNC; Radio Network Controller) and the control station. A diagram showing a universal terrestrial radio access network (UTRAN) 20 including a control station manager 20c (BSM, Base Station Manager) for managing.

In the above configuration, each RNC is connected to a large number of base stations Node Bs.

2 shows a structure of a radio interface protocol according to the 3GPP radio access network standard.

The air interface protocol between the user equipment and the UTRAN consists of a physical layer, a data link layer, and a network layer horizontally, and vertically, the protocol structure includes a control plane and data for transmitting control signals. It is divided into a user plane for transmitting information.

More specifically, referring to FIG. 2, a control layer includes a radio resource control layer (hereinafter, referred to as RRC) as a third layer and a radio link control layer in a second layer. Layer (hereinafter, abbreviated as RLC) and Medium Access Control Layer (hereinafter, abbreviated as MAC), and a physical layer as a first layer.

In the user plane, RLC and MAC are in the second layer, and the physical layer is at the lowest level.

The physical layer provides an information transfer service to a higher layer using various wireless transmission technologies.

The upper MAC layer is connected through a transport channel, and data between the MAC layer and the physical layer moves through the transport channel. The transport channel is divided into a dedicated transport channel (DTCH) and a common transport channel (CTCH), respectively, depending on whether the mobile station is exclusively available or shared by multiple mobile stations.

The MAC layer is connected to the RLC layer by a logical channel, and various logical channels are provided according to the type of information to be transmitted. In general, a control channel is used for transmitting control plane information, and a traffic channel is used for transmitting user plane information.

In addition, the MAC layer provides a reallocation service of radio resources and MAC parameters. This service is performed when the RRC requests reallocation of radio resources or changes of MAC parameters.

The RLC layer provides a radio link establishment and release service. In addition, it performs a segmentation and reassembly function related to an RLC Service Data Unit (hereinafter, abbreviated as SDU) from a higher layer of the user plane.

The RLC SDU is sized to fit the processing capacity in the RLC layer and then header information is added to the MAC layer in the form of a Protocol Data Unit (hereinafter, abbreviated as PDU). At this time, the RLC layer has an RLC buffer for storing the RLC PDUs from the upper layer.

The RRC provides an information broadcast service that broadcasts information to all mobile stations located in an arbitrary area.

It is also responsible for control plane signal processing for control signal exchange in the third layer, and has a function of setting, maintaining and releasing radio resources between the mobile station and the UTRAN.

In particular, the RRC has a function of setting, maintaining, and releasing a radio access bearer, and allocating, relocating, or releasing radio resources required for radio resource access. (The bearer can then be thought of as a defined capability for signaling on the air interface).

Each mobile station includes all radio interface layers, but in UTRAN these protocol layers are separated by radio access network components.

Each protocol layer responsible node is shown in FIG. 3 and will be referred to FIG. 1.

Node B is responsible for the transmission and reception of radio resources with the mobile station and serves as a physical layer.

Node B is managed by the RNC, which is responsible for the management of radio resources. The RNC, which is in charge of Node B's direct management, is called Control RNC, and the CRNC is responsible for the management of public radio resources.

The place that manages dedicated radio resources assigned to each mobile station is called a serving RNC, and the RNC does not change even during handoff.                         

The control RNC (CRNC) and the responsible RNC (SRNC) may be the same, but the control RNC and the responsible RNC may be different when the mobile station moves out of the area of the responsible RNC and moves to another RNC to perform a soft handoff.

The interface between Node B and RNC is called Iub, and the interface between two RNCs is called Iur.

The MAC layer may be further divided into a MAC-d sublayer and a MAC-c / sh sublayer. The MAC-d sublayer manages a dedicated logical channel (DTCH) for a specific mobile station while in the responsible RNC as shown in FIG. 3, and the MAC-c / sh sublayer is located in the control RNC to manage a common transport channel (CTCH). do.

Since the MAC-c / sh sublayer manages a shared transport channel shared by all mobile stations in a cell, there exists one for each cell, and the MAC-d sublayer exists for each mobile station because it provides a dedicated service for the mobile station. .

4 shows the structure of the RLC layer and the MAC layer of the UTRAN side.

When data is transmitted using downlink, the RLC layer stores RLC PDUs in the RLC buffer when data comes down from an upper layer and sends down as many PDUs as required by the MAC layer.

The RLC PDU down to the MAC-d layer is transmitted on a dedicated transport channel or a shared transport channel through channel switching. In the case of transmission on a dedicated transport channel, a header associated with the MAC-d sublayer is attached and sent down to the physical layer through a dedicated channel (DCH).

However, when a common transport channel is allocated, it is transmitted from the MAC-d sublayer to the MAC-c / sh sublayer, and its associated header is attached and multiplexed with other logical channels to enable paging channel (PCH), forward access channel (FAC), It is sent on a shared transport channel such as a downlink shared channel (DSCH).

In the case of uplink, data is transmitted from a common transport channel such as a reverse access channel (RACH) and a common packet channel (CPCH) and a DCH and sent to a higher layer. In this case, it is transmitted to the RLC layer via a path opposite to the downlink.

For example, a case in which data is transmitted through a DSCH, which is a common transport channel, will be described with reference to FIG. 4.

Since the RLC PDU from the RLC layer uses a DSCH, it is transmitted to the MAC-c / sh sublayer through channel switching and control transmission multiplexing. Control transmission multiplexing is responsible for multiplexing multiple logical channels. Data transmitted to the MAC-c / sh sublayer is multiplexed with other logical channels.

In addition, in the common transport channel, various mobile station data can be transmitted, so that the identification table of the destination mobile station is added through multiplexing of the mobile station identification table to indicate the destination of the corresponding data. In this case, TCTF multiplexing is responsible for mapping between logical channels and transport channels. Data mapped to the DSCH transmission channel is transmitted to the DSCH through scheduling considering the priority of the mobile station.

Thereafter, a transport format that can be transmitted in the DSCH is determined, a code to be used is selected, and transmitted to the physical layer.

Hereinafter, a conventional technique for a buffer structure and a management method related to the present invention will be described.

5 shows the structure of the RLC buffer and the status indicators of the RLC buffer.

Each RLC PDU includes a sequence number (SN) in a header and is stored in an RLC buffer according to the serial number.

The stored RLC PDUs are transmitted to the MAC layer (receiving side) as many as required by the MAC layer, and are basically transmitted in serial number order. However, since the state of the wireless channel may not be good, the transmitted data may not be successfully received.

In this case, the RLC layer (sending side) retransmits data that failed to be transmitted. The RLC PDU retransmission method used in the RLC layer selectively retransmits only RLC PDUs that have failed to be transmitted by the Selective Repeat Automatic Repeat reQuest method.

The receiving side (MAC layer) informs the transmitting side (RLC layer) of unsuccessful reception, and the transmitting side can know the RLC PDU to be retransmitted based on the information sent by the receiving side.

The control information used by the receiver to inform the sender of the reception status of the RLC PDUs is transmitted in the form of a status PDU, which includes the serial number of the properly delivered RLC PDU and the RLC PDU that needs retransmission. It contains the serial number and status information of the receiving RLC buffer.

In general, retransmitted RLC PDUs have a higher priority than RLC PDUs transmitted first.                         

The receiver may discover the RLC PDU lost during transmission by observing the serial number of the received RLC PDU. For example, if the serial number of the received RLC PDU was # 23, # 24, # 25, # 32, # 34, it can be said that the RLC PDU having the serial numbers of # 26 ~ # 31 and # 33 has been lost.

The transmitter must store the RLC PDU transmitted for a certain period of time even after the RLC PDU is transmitted in preparation for retransmission. If a message is received that the transmission is successful, the RLC PDU may be removed from the buffer, but if retransmission is requested, the PDU should be retransmitted.

The sender uses Buffer State Managers for buffer management.

Fig. 5 shows a conceptual diagram of VT (S) and VT (A) which are status indicators of the transmitting RLC buffer.

VT (S) means the serial number of the next RLC PDU to be transmitted among the first PDU to be transmitted, VT (A) means the smallest serial number of the PDU waiting for positive acknowledgment (Positive Acknowledgment). That is, PDUs with serial numbers smaller than VT (A) are RLC PDUs that have been successfully transmitted and no longer need to be stored in the buffer.

On the other hand, there is a discussion about a technology that can dramatically increase the transmission speed of downlink centering on the second operation group of 3GPP. The new system is defined as High Speed Data Packet Access (hereinafter referred to as HSDPA), and discussions continue to extend the role of DSCH, the transport channel, and introduce new wireless technologies based on current standards. It is becoming. In particular, in the current system, since the RLC layer is located in the RNC, high-speed packet service is not easy due to the delay time to Node B.

Therefore, in HSDPA, the MAC layer is extended up to Node B and data buffers are placed in Node B so that it can be quickly adapted to a variable radio channel environment to use an efficient scheduling method.

In order to support high-speed packet service, HSDPA system uses ARQ method, Hybrid Automatic Repeat reQuest (hereinafter abbreviated as HARQ) method that combines error correction code, and changes the data transmission rate according to channel status. Adaptive Modulation and Coding (hereinafter abbreviated as AMC) method is used. In addition, in order to reduce the interference effect of the downlink, the UE uses a fast cell site selection (FCS) scheme in which the UE selectively selects a cell and transmits data during soft handoff.

These three technologies are key technologies for supporting high-speed data transmission services, but the delay time between the network and the terminal must be short to support these technologies.

However, in the current system, since the RLC buffer is located in the responsible RNC, considering the delay time between the RNC and the Node B, it is not suitable for the environment assumed in the HSDPA system.

Therefore, in the HSDPA system, the MAC layer is extended to the Node B region and the MAC buffer is provided to enable transmission between the terminal and the network without passing through the RNC region.

6 shows the structure of the MAC layer for the HSDPA system. In 3GPP, the role of the existing DSCH channel is expanded to support high-speed data service, and the DSCH channel used in the HSDPA system is defined as HS-DSCH (HSDPA Downlink Shared Channel).

As described above, a MAC HS-DSCH sublayer having a buffer is added to the Node B in order to reduce the delay time between the mobile station and the network.

The MAC HS-DSCH sublayer performs part of the existing MAC-c / sh sublayer function, and a function for HARQ has been added. The RLC PDU from the RLC is stored in the buffer of the MAC HS-DSCH sublayer through the MAC-d sublayer and the MAC-c / sh sublayer, and then transmitted to the terminal (mobile station) at an appropriate time. (In the future, the buffer located in the MAC HS-DSCH sublayer is defined as a MAC buffer.)

Since the HARQ function requires the functions of the MAC layer and the physical layer at the same time, the related control is performed in the "HARQ" block located in the MAC HS-DSCH. There is a MAC buffer in the HARQ block, and one HARQ block exists for each terminal. The number of MAC PDUs that can be stored in the MAC buffer may be set from a control signal through the RRC, and the MAC layer may request an additional amount of data necessary for the RLC layer.

Figure 7 shows the node in charge for each protocol layer of the HSDPA system. The RLC layer, MAC-d, and MAC-c / sh sublayers are located in the same manner as the existing 3GPP standard, and a MAC HS-DSCH sublayer is added to the Node B on the physical layer.

In the HSDPA system, the MAC layer is extended from Node B to the Node B, and the data buffer is placed in Node B to quickly adapt to the variable radio channel environment. However, as the buffer is located at the MAC layer, Due to consideration, there was no efficient buffer management method by using the MAC buffer which performs the similar function while continuing to use the RLC buffer.                         

Therefore, the present patent proposes a standard for the exchange and operation of control information signals for supporting the MAC buffer in the HSDPA system.

The present invention has been made to solve the above-described problems, in the present invention, by adding a function related to the MAC buffer added to the HSDPA system, and defines the relationship between the RLC buffer and the RLC buffer and MAC buffer coexist We propose an efficient buffer management method in the system.

That is, the buffer status indicators for MAC and RLC are set for managing the MAC buffer and the RLC buffer, and the VT (S) and VT (A) necessary for transmission and retransmission are updated using the buffer status indicator, and the status By using indicators, we propose an efficient buffer management method that can request additional data by comparing MAC and RLC buffer sizes and reference values.

According to another aspect of the present invention, there is provided a buffer management method for supporting a HSDPA system of a mobile communication, the method including: adding a MAC buffer, which is a data buffer, by extending a MAC layer; Transmitting and storing data to the Mac buffer at an upper RLC layer; Updating data retransmission and buffer status for efficient management of the RLC buffer and the Mac buffer; And providing additional data according to the buffer status of the MAC layer.                     

In the present invention, the MAC (MAC) buffer is characterized in that it is added to the Node B.

In the present invention, the additional data supply to the MAC layer is characterized in that if the number of stored MAC PDUs decreases below the threshold value, the Mac buffer is provided by the data request to the RLC buffer or voluntarily provided from the RLC buffer to the MAC buffer.

In addition, the MAC layer on the receiving side provides positive or negative response information to the MAC layer on the transmitting side for retransmission of MAC PDUs lost during transmission in the step of updating the retransmission and buffer status of the present invention, and VT_MAC (M ), VT_MAC (S) or VT_MAC (A).

In addition, in the step of updating the retransmission and buffer status of the present invention, the transmitting MAC buffer status indicators are updated according to the acknowledgment or negative response information sent from the receiving MAC layer and reported to the RLC layer.

In addition, the information reported to the RLC layer in the present invention is characterized by including the serial number of the RLC PDUs successfully transmitted in the MAC layer in addition to the update information of the MAC buffer status indicators.

Also, in the retransmission and buffer status update of the present invention, the RLC layer can grasp the status of the MAC buffer through the information reported from the MAC layer, and VT (A) and VT (S) of the sender RLC buffer status indicators It is updated by a status PDU including a positive or negative response sent from a receiving RLC layer, and VT (MAC_S), VT (MAC_A) or VT (MAC_M) is updated based on information transmitted from a MAC layer which is a lower layer. It is done.                     

In the present invention, VT (S) and VT (A) of the RLC buffer status indicator value is characterized by having a value equal to or less than VT (MAC_S) and VT (MAC_A).

Also, in the present invention, VT (A) and VT (S) of the sender RLC buffer status indicators are added to VT (MAC_A) and VT (MAC_S) information, which is the status information of the RLC buffer updated by information sent from the MAC layer, which is a lower layer. Updating is also possible, and in this case, VT (S) and VT (A) of the RLC buffer status indicator value have the same value as VT (MAC_S) and VT (MAC_A).

Also, in the present invention, the additional data request for the RLC buffer may include a difference between the VT_MAC (M) value and the VT_MAC (A) value, which are MAC buffer status indicators, is smaller than the threshold value B _TH1 received from the RRC, or the VT_MAC (M) value and the VT_MAC value. (S) is a case where the difference is _smaller than the threshold value B _TH2 received from the RRC.

In the present invention, the RLC PDU is supplied to the MAC buffer in the RLC layer, the difference between the VT (MAC_M) value and the VT (MAC_A) value of the RLC buffer status indicator is smaller than the threshold value (B _TH1 ) received from the RRC, or VT (MAC_M). When the difference between the value and VT (MAC_S) value is smaller than the threshold value (B _TH2 ) received from the RRC, it is characterized by supplying the RLC PDU as much as the amount suggested by the RRC layer.

In addition, in the present invention, the threshold value is transmitted from the RRC layer through a call setup or reset process, and the threshold value is derived in consideration of the effects of the size of the RLC buffer, the data rate, and the transmission delay time between the RNC and the Node B. It is characterized by.

Other objects and features of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.                     

Hereinafter, a buffer management method for supporting a HSDPA system of a mobile communication according to the present invention will be described with reference to the accompanying drawings.

First, the present invention will be described in general, and relates to an efficient buffer management method in a system in which an RLC buffer and a MAC buffer coexist by adding a function related to a MAC buffer added to an HSDPA system and defining an association with an RLC buffer. Hereinafter, each drawing will be described with reference to FIG. 10.

8 shows the structure of the MAC buffer added to Node B of the RNC for the HSDPA system (step 101).

That is, the MAC buffer structure and MAC buffer status indicators of the HSDPA system are shown.

In FIG. 8, the status indicators on the buffer indicate the beginning of the associated buffer and are indicated by arrows.

The RLC PDU from the RLC passes through the MAC-d sublayer and the MAC-c / sh sublayer and is stored in the MAC buffer in the form of a MAC PDU.

Like the RLC PDU, a serial number is designated in the header of the MAC PDU and stored in the MAC buffer according to the designated serial number. (Step 102).

Since the size of the MAC buffer may be different from that of the RLC buffer, the serial number of the MAC header is assigned differently from the serial number of the RLC PDU. As in the RLC layer, the MAC PDU lost during transmission is retransmitted by a selective retransmission request method, and the receiving MAC layer provides positive or negative response information for retransmission.

In a similar concept to the conventional RLC buffer, the following sender MAC buffer status indicator is used (step 103).

VT_MAC (M): Serial number of MAC PDU to be supplied from RLC next time

VT_MAC (S): Serial number of MAC PDU to be transmitted next

VT_MAC (A): The smallest serial number among MAC PDUs requiring retransmission.

VT_MAC (S) and VT_MAC (A) play the same role as VT (S) and VT (A) used in the RLC buffer, respectively. The MAC buffer status indicators are updated according to the information such as the acknowledgment, the negative response, etc. sent from the receiving MAC layer of the terminal (mobile station), and the updated information is reported to the RLC layer.

The reported information includes serial numbers of RLC PDUs successfully transmitted in the MAC layer, in addition to update information of the MAC buffer status indicators (step 104).

In the RLC layer, the status of the MAC buffer can be determined through the information reported by the MAC layer.

In the RLC layer, the following RLC buffer status indicators are defined in addition to the conventional VT (S) and VT (A) as shown in FIG. (Step 105).

VT (MAC_S): Serial number of RLC PDU included in MAC PDU with serial number of VT_MAC (S)

VT (MAC_A): Serial number of RLC PDU included in MAC PDU with serial number of VT_MAC (A)

VT (MAC_M): Serial number of RLC PDU included in MAC PDU with serial number of VT_MAC (M)                     

Figure 9 shows the RLC buffer structure and RLC buffer status indicators of the HSDPA system.

In FIG. 9, it is assumed that the values of VT (S) and VT (A) are updated through the negative response, the positive response, and the RLC buffer status information included in the status PDU of the receiving RLC layer, as in the conventional system. . (Step 106).

Accordingly, in FIG. 9, even though the transmission of the MAC PDU is successful, the value of VT (S) is not updated, and thus, VT (S) may have a smaller value than VT (MAC_S). For the same reason, VT (A) may also have a smaller value than VT (MAC_A).

The VT (S) and VT (A) information is basically updated according to the information in the PDU sent from the receiving RLC layer, but the information of VT (MAC_S), VT (MAC_A) and VT (MAC_M) is stored in the lower layer. It is updated by the information sent from the MAC layer.

Therefore, the information of the VT (S) can be updated slower than the VT (MAC_S) information so that the VT (MAC_S) value is always equal to or larger than that of the VT (S) (step 106).

1) When updated through a status PDU sent from the receiving RLC:

As described above, the VT (A) and VT (S) values are updated by the information sent by the receiving side RLC, and the update information of VT (MAC_A), VT (MAC_S) and VT (MAC_M) is sent by the MAC layer. It is loaded in MAC-STATUS-Ind information.

VT(MAC_S)이다. 마찬가지로, VT(A)와 VT(MAC_A)값이 다를 수 있으며 VT(A)

VT(MAC_A)이다. In this case, the values of VT (S) and VT (MAC_S) may be different, and VT (S)

VT (MAC_S). Similarly, the values of VT (A) and VT (MAC_A) can be different and VT (A)

VT (MAC_A).

In detail, these MAC-STATUS-Ind information may include serial numbers of RLC PDUs successfully transmitted in the MAC buffer.

On the other hand, the updating method of the VT (S) and the VT (A) can be different as follows according to the setting information at the time of the setting of the radio access bearing (step 107).

2) When updated by MAC buffer information sent from MAC layer, which is lower layer:

This is a case where VT (A) and VT (S) are updated using VT (MAC_A) and VT (MAC_S) which are status information of the RLC buffer updated by information sent from the MAC layer, which is a lower layer.

In this case, VT (A) = VT (MAC_A) and VT (S) = VT (MAC_S) are set.

The MAC buffer stores some of the data sent from the RLC.

The MAC PDUs that are no longer needed at the end of the transfer are deleted, and when the number of stored MAC PDUs decreases below the threshold, an additional MAC PDU is requested in the RLC buffer (it does not matter here, because the RLC PDU requires a MAC). If the header is attached, it becomes a MAC PDU).

The threshold value used is transmitted from the RRC layer through the call setup or reconfiguration process. The value is affected by the size of the RLC buffer, the size of the MAC buffer, the data transmission speed, and the transmission delay time between the RNC and Node B. The decision is made in consideration of the above.

When additional data is requested to the RLC buffer, information of the MAC buffer status indicators VT_MAC (M), VT_MAC (A), or VT_MAC (S) can be used.

If the difference between the VT_MAC (M) and VT_MAC (A) values is less than the threshold (B _TH1 ) or the difference between the VT_MAC (M) and VT_MAC (S) values is less than the threshold (B _TH2 ) This means that there is not much data left, so you can request additional data from the RLC buffer. (Step 108).

In the same principle as step 108, even if there is no request of the MAC layer, the RLC layer may additionally transmit data using status indicators related to the MAC buffer.

That is, when the difference between the VT (MAC_M) value and the VT (MAC_A) value is smaller than the threshold value B _TH1 or the difference between the VT (MAC_M) value and the VT (MAC_S) value is smaller than the threshold value B _TH2 , RRC After transmitting the RLC PDUs as much as the amount suggested by the layer to the MAC layer, the value of the VT (MAC_M) is updated (step 109).

11 and 12 show a method of additionally transmitting the RLC PDU to the MAC buffer, and FIGS. 11 and 12 are fully mentioned in the detailed description of the present invention (steps 108,109) and will be described in brief instead of the detailed description.

In FIG. 11, the MAC layer requests an additional RLC PDU to the RLC layer using the MAC buffer status indicator, and FIG. 12 illustrates a case in which the RLC layer voluntarily supplies the additional RLC PDU to the MAC buffer through the status indicator of the RLC buffer. to be.

At this time, assuming that the size of the RLC buffer is N _RLC and the size of the MAC buffer is N _MAC , the operation between the status indicators must perform a Modulo operation.

As described above, the present invention extends the MAC layer to add a MAC buffer, which is a data buffer, to the Node B of the RNC, and transfers data to the Mac buffer from the upper RLC layer to form a Mac buffer in the form of a Mac PDU. In order to efficiently manage the RLC buffer and Mac buffer, data retransmission and buffer status are updated between the RLC layer and the MAC layer, and additional RLC PDUs are provided by the MAC layer request or the RLC layer according to the buffer state of the MAC layer. The buffer management method for supporting the HSDPA system, characterized in that.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments.

Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

As described above, the present invention provides a variety of buffer management methods that can be interoperated with the existing system while having a buffer in the Node B in the HSDPA system that provides a high-speed packet data service in the downlink, HSDPA system is present It can be used in conjunction with the specifications provided by 3GPP.

Claims (13)

In buffer operation of mobile communication system, Expanding the MAC layer to add a MAC buffer, which is a data buffer; Transmitting and storing data to the Mac buffer at an upper RLC layer; And a data retransmission and updating a buffer status for efficient management of the RLC buffer and the Mac buffer. The buffer management method of claim 1, further comprising providing additional data according to the buffer status of the MAC layer. The method of claim 2, wherein the supply of additional data to the MAC layer is characterized in that the MAC buffer is provided by the data request to the RLC buffer or voluntarily provided from the RLC buffer to the MAC buffer when the number of stored MAC PDUs decreases below the threshold. Buffer management method to support HSDPA system. 2. The method of claim 1, wherein the MAC layer at the receiving side provides acknowledgment or negative response information to the MAC layer at the transmitting side for retransmission of MAC PDUs lost during transmission in the retransmission and updating the buffer status, and as the information, VT_MAC. (M), VT_MAC (S) or VT_MAC (A) using a buffer management method for supporting the HSDPA system, characterized in that. The method of claim 1, wherein in the step of updating the retransmission and the buffer status, the sending MAC buffer status indicators update according to the acknowledgment or negative response information sent from the receiving MAC layer and report to the RLC layer. Buffer management method The method of claim 5, wherein the information reported to the RLC layer includes serial numbers of RLC PDUs successfully transmitted in the MAC layer, in addition to update information of the MAC buffer status indicators. The method according to claim 1 or 5, wherein in the retransmission and updating the buffer status, the RLC layer can determine the status of the MAC buffer through the information reported from the MAC layer, and the VT (A) of the sender RLC buffer status indicators. The VT (S) is updated by a status PDU containing a positive or negative response sent from the RLC layer of the receiving side, and VT (MAC_S), VT (MAC_A) or VT (MAC_M) is applied to the information transmitted from the MAC layer which is a lower layer. The buffer management method for supporting the HSDPA system, characterized in that updated according to. 8. The method of claim 7, wherein VT (S) and VT (A) of the RLC buffer status indicator value have a value equal to or less than that of VT (MAC_S) and VT (MAC_A). . The VT (A) and VT (MAC_S) of claim 7, wherein VT (A) and VT (S) of the transmitting RLC buffer status indicators are status information of the RLC buffer updated by information sent from the MAC layer, which is a lower layer. It is also possible to update the information.In this case, VT (S) and VT (A) of the RLC buffer status indicator value have the same values as VT (MAC_S) and VT (MAC_A). Way. 4. The method of claim 3, wherein the request for additional data to the RLC buffer is based on a difference between the VT_MAC (M) value and the VT_MAC (A) value, which are MAC buffer status indicators, less than the threshold value B _TH1 received from the RRC or the VT_MAC (M) value. And a case in which the difference between the VT_MAC (S) value is smaller than the threshold value B _TH2 received from the RRC. 4. The method according to claim 3, wherein the difference between the VT (MAC_M) value and the VT (MAC_A) value, which is the RLC buffer status indicator, is smaller than the threshold value B _TH1 received from the RRC. Buffer management to support HSDPA system, which supplies RLC PDU as much as suggested by RRC layer when difference between (MAC_M) value and VT (MAC_S) value is smaller than threshold value (B _TH2 ) received from RRC. Way. 12. The method of claim 10 or 11, wherein a threshold value is transmitted from the RRC layer through a call setup or reconfiguration process. The threshold value includes a size of the RLC buffer, a data transmission rate, and a transmission delay time between the RNC and the Node B. Buffer management method for supporting the HSDPA system, characterized in that derived by considering the impact. 2. The method of claim 1, wherein a MAC buffer is added to Node B.

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