KR100937434B1 - Method of buffer status reporting in a wireless communication system - Google Patents

Abstract

The present invention relates to a buffer status reporting method in a wireless communication system. In one aspect of the present invention, in a wireless communication system, a terminal transmits a first buffer status report indicating a buffer status of a terminal to a base station. After the successful transmission of the first buffer status report, the terminal fails to receive allocation information indicating allocation of radio resources for transmission of uplink data until a predetermined time elapses. Trigger the transfer procedure.

Radio resource allocation, scheduling request (SR) information, buffer status report, BSR

Description

Method of buffer status reporting in a wireless communication system

The present invention relates to a wireless communication system, and more particularly, to a buffer status reporting method in a wireless communication system.

In a wireless communication system using a multi-carrier scheme such as orthogonal frequency division multiple access (OFDMA) or single carrier-frequency division multiple access (SC-FDMA), a radio resource is a set of continuous sub-carriers and is a two-dimensional space. It is defined by the time-frequency region of. One time-frequency domain is divided into rectangles determined by time coordinates and subcarrier coordinates. That is, one time-frequency region may be divided into a rectangle partitioned by symbols on at least one or more time axes and subcarriers on a plurality of frequency axes. Such a time-frequency region may be allocated to an uplink of a specific UE or a base station may transmit the time-frequency region to a specific user in downlink. To define such a time-frequency domain in two-dimensional space, the number of consecutive subcarriers starting at a position separated by the number of OFDM symbols in the time domain and an offset from a reference point in the frequency domain should be given.

In an E-UMTS (Evolved Universal Mobile Telecommunications System) system currently under discussion, a radio frame of 10 ms is used, and one radio frame includes 10 subframes. In addition, one subframe consists of two consecutive slots. One slot is 0.5ms long. In addition, one subframe includes a plurality of OFDM symbols, and some symbols (eg, first symbols) of the plurality of OFDM symbols are used to transmit L1 / L2 control information.

FIG. 1 illustrates an example of a physical channel structure used in an E-UMTS system, and one subframe includes an L1 / L2 control information transmission area (hatched part) and a data transmission area (unhatched part). do.

2 is a view for explaining a general method for transmitting data in the E-UMTS. E-UMTS uses Hybrid Auto Repeat reQuest (HARQ), which is one of the data retransmission techniques, in order to improve throughput and perform smooth communication.

Referring to FIG. 2, the base station uses downlink scheduling information (Downlink Scheduling Information) through a DL L1 / L2 control channel, for example, a physical downlink control channel (PDCCH) in order to transmit data to a terminal by HARQ scheme. 'DL scheduling information' is transmitted. The DL scheduling information includes a terminal identifier or a group identifier of UEs (UE Id or Group Id), location and duration of radio resources allocated for transmission of downlink data, duration of assignment information, modulation scheme, and pay. Transmission parameters such as load size, MIMO-related information, HARQ process information, redundancy version, and identification information (New Data Indicator) as to whether new data may be included.

In order to indicate which UE the DL scheduling information transmitted through the PDCCH is for, the UE identifier (or group identifier), for example, a Radio Network Temporary Identifier (RNTI) is transmitted. The RNTI may be divided into a dedicated RNTI and a common RNTI. The dedicated RNTI is used for data transmission and reception to a terminal whose information is registered in the base station. The common RNTI is used for communication with terminals that have not been allocated a dedicated RNTI because information is not registered in a base station, or for transmitting and receiving information commonly used by a plurality of terminals such as system information. For example, RA-RNTI or T-C-RNTI used in a random access process through a random access channel (RACH) is an example of a common RNTI. The terminal identifier or the group identifier may be transmitted in the form of CRC masking on DL scheduling information transmitted through the PDCCH.

UEs in a specific cell monitor the PDCCH through the L1 / L2 control channel using the RNTI information they have, and receive DL scheduling information through the corresponding PDCCH when CRC decoding is successful with the RNTI. The terminal receives downlink data transmitted to itself through a physical downlink shared channel (PDSCH) indicated by the received DL scheduling information.

As described above, uplink and downlink scheduling is performed to efficiently use limited radio resources in a wireless communication system. In particular, in a system using multiple carriers such as OFDMA or SC-FDMA, a radio resource block constituted by a specific time interval and a specific frequency band can be used by only one terminal, and thus a certain time point for each terminal. Scheduling to decide how much radio resources to allocate in the system is very important.

For scheduling, the terminal may perform a buffer status report (BSR) and a channel resource request. The terminal may inform the network of the amount of data stored in its buffer through the buffer status report, so that the network can efficiently perform the scheduling. The network may perform appropriate scheduling by identifying which terminal needs a certain amount of radio resources by using the buffer status report from the terminal. Meanwhile, the terminal may actively request to allocate radio resources to the network.

The buffer status report and the channel resource request by the terminal need to be performed without error because the network is very important for proper scheduling. If an error occurs in the buffer status report and channel resource request process by the terminal, the network will not allocate radio resources to the terminal during the scheduling process. Although there is data to be transmitted, the terminal cannot receive radio resources and thus cannot perform communication smoothly.

The present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to provide a method that can efficiently use radio resources in a wireless communication system.

Another object of the present invention is to provide a method of increasing the reliability of a buffer status report and a channel resource request by a terminal in a wireless communication system.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above are apparent to those skilled in the art from the following detailed description. Can be understood.

In an aspect of the present invention, in a wireless communication system, a terminal requests allocation of radio resources for transmission of uplink data at least once to a base station according to a first radio resource allocation request method. If a predetermined condition is satisfied, the terminal requests allocation of radio resources for transmission of the uplink data to the base station according to a second radio resource allocation request method.

In another aspect of the present invention, in a wireless communication system, a terminal transmits a first buffer status report indicating a buffer status of a terminal to a base station. After the successful transmission of the first buffer status report, the terminal fails to receive allocation information indicating allocation of radio resources for transmission of uplink data until a predetermined time elapses. Trigger the transfer procedure. In this case, the transmission procedure of the second buffer status report may be performed through a random access process or a transmission process of a scheduling request information (SR) channel.

In another aspect of the present invention, in a wireless communication system, the terminal triggers a buffer status reporting procedure when a predetermined predetermined condition is satisfied. If there is no uplink radio resource allocated while the buffer status reporting procedure is triggered, scheduling request (SR) information is transmitted to the base station to receive an uplink channel resource for the buffer status reporting.

According to the present invention, it is possible to efficiently use radio resources in a wireless communication system and to increase the reliability of a buffer status report and a channel resource request by a terminal.

The construction, operation, and other features of the present invention will be readily understood by the embodiments of the present invention described with reference to the accompanying drawings. The embodiments described below are examples in which technical features of the present invention are applied to an Evolved Universal Mobile Telecommunications System (E-UMTS).

3 is a diagram illustrating a network structure of an E-UMTS. The E-UMTS system is an evolution from the existing WCDMA UMTS system and is currently undergoing basic standardization work in the 3rd Generation Partnership Project (3GPP). E-UMTS is also called a Long Term Evolution (LTE) system.

Referring to FIG. 3, an E-UTRAN consists of base stations (hereinafter, abbreviated as 'eNode B' or 'eNB'). The eNBs are connected via an X2 interface. The eNB is connected to a user equipment (hereinafter abbreviated as UE) through an air interface and is connected to an Evolved Packet Core (EPC) through an S1 interface. The EPC includes a Mobility Management Entity (MME) / System Architecture Evolution (SAE) gateway.

Layers of the radio interface protocol between the terminal and the network are based on the lower three layers of the Open System Interconnection (OSI) reference model, which is widely known in communication systems. L2 (second layer), L3 (third layer) can be divided into, wherein the physical layer belonging to the first layer provides an information transfer service (Information Transfer Service) using a physical channel, The radio resource control layer (hereinafter referred to as RRC) layer located in the third layer plays a role of controlling radio resources between the terminal and the network. To this end, the RRC layer exchanges RRC messages between the UE and the network. The RRC layer may be distributed to network nodes such as Node B and AG, or may be located independently of Node B or AG.

4 is a schematic diagram of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN). In FIG. 4, the hatched portion illustrates the functional entities of the user plane and the unhatched portion illustrates the functional entities of the control plane.

5A and 5B illustrate a structure of a radio interface protocol between a UE and an E-UTRAN. FIG. 5A is a control plane protocol configuration diagram and FIG. 5B is a user plane protocol configuration diagram. . The air interface protocols of FIGS. 5A and 5B are horizontally composed of a physical layer, a data link layer, and a network layer, and vertically a user plane for transmitting data information. It is divided into User Plane and Control Plane for Signaling. The protocol layers of FIGS. 5A and 5B are based on the lower three layers of the Open System Interconnection (OSI) reference model, which are well known in communication systems, based on L1 (first layer), L2 (second layer), It may be classified as L3 (third layer).

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. In E-UMTS, the physical channel is modulated by an orthogonal frequency division multiplexing (OFDM) scheme, thereby utilizing time and frequency as radio resources.

The medium access control (hereinafter, referred to as MAC) layer 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. The PDCP layer of the second layer performs a header compression function to reduce unnecessary control information in order to efficiently transmit data transmitted using an IP packet such as IPv4 or IPv6 in a relatively low bandwidth wireless section. .

The radio resource control layer (hereinafter referred to as RRC) layer located at the bottom of the third layer is defined only in the control plane, and the configuration and resetting of the radio bearer (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, RB means a service provided by the second layer for data transmission between the terminal and the UTRAN.

Downlink transmission channels for transmitting data from the network to the UE include a broadcast channel (BCH) for transmitting system information, a paging channel (PCH) for transmitting a paging message, and a downlink shared channel (SCH) for transmitting user traffic or control messages. There is). Traffic or control messages of a downlink multicast or broadcast service may be transmitted through a downlink SCH or may be transmitted through a separate downlink multicast channel (MCH). Meanwhile, the uplink transmission channel for transmitting data from the terminal to the network includes a random access channel (RAC) for transmitting an initial control message and an uplink shared channel (SCH) for transmitting user traffic or control messages.

Above logical channels, logical channels mapped to transport channels include BCCH (Broadcast Channel), PCCH (Paging Control Channel), CCCH (Common Control Channel), MCCH (Multicast Control Channel), MTCH (Multicast Traffic Channel) ).

In the E-UMTS system, the OFDM scheme is used in downlink, and the SC-FDMA (Single Carrier-Frequency Division Multiple Access) scheme is used in uplink. The OFDM system, which is a multi-carrier method, is a system for allocating resources in units of a plurality of subcarriers in which a part of carriers is grouped, and uses Orthogonal Frequency Division Multiple Access (OFDMA) as an access method.

6 is a process flow diagram of an embodiment of the present invention.

FIG. 6 shows that if a predetermined condition is satisfied after requesting allocation of radio resources for transmission of uplink data to the base station eNB at least once by the UE according to the first radio resource allocation request method, FIG. The present invention relates to an embodiment of requesting allocation of radio resources for transmission of the uplink data to the base station according to a radio resource allocation request method.

In FIG. 6, the first radio resource allocation request method is a radio resource allocation request method using a scheduling request (SR) channel, and the second radio resource allocation request method is a radio resource allocation request method through a RACH process. However, the present invention is not limited thereto, and the first and second radio resource allocation request methods may be any radio resource allocation request methods.

The SR channel is a physical layer channel used in the LTE system and consists of 1 bit. A terminal assigned an SR channel from a base station may request allocation of an uplink radio resource to the base station by setting an SR channel to, for example, “1”. Since the SR channel is composed of 1 bit, an error may occur during transmission. In addition, since the SR channel can be used in a state in which the terminal is synchronized with the base station, even if the terminal is assigned an SR channel, the radio resource request through the SR channel is successfully performed when the terminal is in an asynchronous state with the base station. Can't be.

Referring to FIG. 6, the UE, which is allocated an SR channel from an eNB, sets an SR channel to “1” to request an uplink radio resource when data to be transmitted to the base station is transmitted to the base station. [S61]. The terminal may use the SR channel when it is necessary to perform uplink data to be transmitted in a state in which no uplink radio resource is allocated, for example, a buffer status report (BSR). Alternatively, the SR channel may be used when data with higher priority than data stored in a buffer occurs. Alternatively, even when there is an uplink radio resource allocated by the terminal, when the data to be transmitted is additionally generated or a change in the buffer state occurs, 1-bit information may be transmitted to the base station through an SR channel.

After transmitting 1 bit information through the SR channel, the terminal drives the timer (T1). The driving time of the timer may be a transmission time of the 1 bit information or a time of receiving acknowledgment information (ACK) for the 1 bit information. If the radio resource is not allocated from the base station until the timer expires, the terminal requests radio resource allocation by retransmitting 1 bit information through the SR channel [S62] and drives the timer again.

In the process, when uplink radio resources are allocated from the base station, transmission of 1 bit information is stopped through the SR channel, and the terminal transmits uplink data to the base station through the allocated radio resources. Even after repeating the above process for a predetermined number of times [S63], if the radio resource is not allocated from the base station, the terminal performs a random access procedure (RACH procedure) to request the radio resource to be allocated to the base station [ S64]. In this case, the terminal releases a call with or separately from the RACH procedure or informs the base station that an error condition has occurred. The transmission period (or the timer T1 value) of the 1-bit information through the SR channel or the predetermined number of times may be known to the terminal by being included in system information or a dedicated RRC message previously transmitted from the base station.

A modification of the embodiment of FIG. 6 is as follows. In step S61, the terminal drives the timer after transmitting the SR channel. The terminal repeatedly transmits an SR channel until an uplink channel resource is allocated until the timer expires. At this time, the SR channel may be transmitted periodically. If the uplink channel resource is not allocated until the timer expires, the terminal performs an RACH process to request allocation of the uplink channel resource.

7 is a process flow diagram according to another embodiment of the present invention. The embodiment of FIG. 7 is an example for the UE to perform a Buffer Status Report (BSR) to the eNB.

The BSR is performed by the terminal to inform the base station of its buffer state, and FIGS. 8A and 8B illustrate data formats of short BSR and long BSR, respectively. In FIG. 8A, an LCG ID means a logical channel group identifier. The terminal may group up to four logical channels into one logical channel group and report a buffer status for each logical channel group. This grouping can reduce overhead that may occur when buffer status is reported for each logical channel. In the grouping method for the logical channels, the base station may inform the terminal. The long BSR of FIG. 8B includes four buffer size fields corresponding to each of LCG ID # 1 to # 4. Each buffer size field includes the size of all data waiting to be transmitted to the RLC layer and PDCP layer included in the corresponding logical channel group.

The BSR of FIG. 8A or 8B is transmitted in a MAC protocol data unit (MAC PDU). That is, it is included in the BSR control element, which is one of control elements of the MAC PDU generated in the MAC layer of the UE.

9A to 9C are diagrams for describing the format of a MAC PDU. 9A to 9C, the LCID indicates which logical channel the corresponding MAC SDU (MAC Service Data Unit) is or what kind of information is included in the corresponding MAC control element. The LCID corresponding to the BSR control element distinguishes whether the corresponding BSR is a short BSR or a long BSR. The E (extension) field includes information indicating whether there is another MAC subheader after the corresponding MAC subheader. The F field contains information indicating the length of the following L field. The R (reserved) field is a reserved field.

If a certain condition is satisfied, the buffer status reporting process is triggered in the terminal. At this time, if there is a radio resource allocated to the terminal, the BSR is transmitted through the allocated radio resource. If there is no radio resource allocated to the terminal and the SR channel is established, the terminal transmits 1 bit information to the base station through the SR channel. If the SR channel is not configured, the terminal transmits a BSR to the base station through an RACH process. Even when the UE that has been performing uplink data transmission in the state of the allocated uplink radio resource transitions to the state in which the allocated radio resource is not present, the UE may perform the BSR transmission procedure using the SR channel or the RACH process. have. In this case, the BSR transmission procedure is preferably started after a predetermined time elapses after the UE checks its buffer status. When the radio resource is allocated from the base station before the predetermined time elapses, the terminal transmits the BSR through the allocated radio resource without performing an SR channel transmission process or an RACH process.

Referring to FIG. 7, when the MAC layer of the terminal instructs the terminal physical layer to start a random access process, the terminal physical layer first selects one access slot and one signature and randomly selects one random access procedure. The access preamble is transmitted to the base station [S71].

When the terminal transmits the preamble, the base station transmits a response message through a downlink physical channel (for example, an Acquisition Indicator Channel (AICH)) [S72]. The AICH transmitted in response to the preamble transmits a signature corresponding to the preamble during the first predetermined length of the access slot corresponding to the access slot to which the preamble is transmitted. The base station allocates an uplink radio resource (UL grant) to the terminal through the RACH response message. The uplink radio resource is an UL-SCH (Uplink Shared Channel). The terminal transmits the MAC PDU including the BSR by using radio resource allocation information, message size, and radio parameter included in the RACH response message [S73]. Upon receiving the MAC PDU transmitted from the terminal, the base station transmits an ACK / NACK or contention resolution message to the terminal [S74].

When it is confirmed that the MAC PDU including the BSR has been successfully transmitted, for example, when receiving an ACK or a collision resolution message including the identifier of the terminal from the base station, the terminal drives the timer T2. If uplink radio resources are allocated from the base station before the timer expires, the terminal transmits data stored in a buffer to the base station using the allocated radio resources.

If the uplink radio resource is not allocated from the base station until the timer expires, the terminal considers that the BSR transmission through the RACH process has failed and triggers a new BSR process. That is, the UE attempts to transmit the BSR by performing the RACH process again [S75] or, if the SR channel is configured in the UE, transmits 1-bit information through the set SR channel to receive the radio resource and then allocates the radio resource. Send BSR through

In the process, when the BS is instructed not to perform the BSR transmission process, the SR channel transmission process, or the RACH process anymore, the timer T2 is stopped or the BSR transmission process is triggered any longer even when the timer expires. I never do that.

Referring to the embodiment of Figure 7 more generally as follows. That is, the terminal transmits a first BSR indicating the buffer status of the terminal to the base station. After the successful transmission of the first BSR, the terminal triggers a transmission procedure of the second BSR when the allocation information indicating the allocation of radio resources for the transmission of the uplink data is not received until a predetermined time elapses. do. In this case, the transmission procedure of the second BSR may be performed through a RACH procedure or an SR channel transmission procedure. When the SR channel is periodically configured in the terminal, the terminal preferably performs a BSR transmission process using a radio resource for the RACH preamble transmission and a radio resource for the SR channel having a fast allocation time.

10 is a flowchart of a procedure according to another embodiment of the present invention.

Referring to FIG. 10, the UE transmits 1 bit information to the base station eNB through the SR channel to perform a buffer status report (BSR) [S101]. When receiving 1 bit information from the terminal through the SR channel, the base station allocates an uplink radio resource, for example, UL-SCH to the terminal [S102]. The terminal transmits the MAC PDU including the BSR to the base station through the allocated uplink radio resource [S103].

If the MAC PDU is successfully received, the base station transmits an acknowledgment (ACK) to the terminal [S104]. Upon receiving the ACK, the terminal drives the timer T3 and waits for allocation of an uplink radio resource for transmitting uplink data stored in a buffer of the terminal until expiration of the timer. If the uplink radio resource is allocated from the base station before the timer expires, the terminal transmits uplink data to the base station through the allocated uplink radio resource. If the uplink radio resource is not allocated until the timer expires, the UE transmits an SR channel or performs an RACH process to perform the BSR process again [S105]. In FIG. 10, the terminal may drive the timer T3 from the time when the terminal transmits the BSR in step S103.

11 is a process flow diagram according to another embodiment of the present invention.

Referring to FIG. 11, a UE transmits a MAC PDU including a BSR to an eNB through an SR channel transmission, an RACH procedure, or a pre-allocated uplink radio resource [S111]. If the base station does not successfully receive the MAC PDU transmitted from the terminal, the base station transmits a NACK to the terminal [S112]. If an error occurs in the transmission of the NACK, the terminal receives an ACK [S112]. Accordingly, the terminal determines that the BSR has been successfully transmitted and waits for the allocation of the uplink radio resource. However, since the base station has not successfully received the BSR, the terminal does not allocate the uplink radio resource. Alternatively, even when the base station successfully receives the BSR, if there is no radio resource available, the base station does not allocate radio resources to the terminal.

In this case, the terminal checks whether there is a radio resource allocated to all HARQ processes configured in the mobile station [S114], and if there is no radio resource allocated to all HARQ processes, the terminal drives the timer T4. If the radio resource is allocated from the base station before the timer expires, the terminal stops the timer. If the radio resource is not allocated from the base station until the timer expires, the terminal triggers a buffer status report (BSR) by transmitting 1-bit information through the SR channel or performing a RACH process [S115].

In the embodiment of FIG. 11, the existence of radio resources allocated to a specific HARQ process means that data to be transmitted to the base station remains in the HARQ buffer of the corresponding HARQ process. Alternatively, the fact that there is a radio resource allocated to a specific HARQ process means that after the radio resource for initial data transmission is allocated to the HARQ process, retransmission has not occurred as much as the maximum number of retransmissions in the HARQ process and is most likely for the HARQ process. This means that the feedback received recently is NACK. Alternatively, the presence of radio resources allocated to a specific HARQ processor means a state in which radio resources for initial data transmission are allocated to the HARQ process.

As another embodiment of the present invention, an embodiment using the SR channel for other purposes may be considered. That is, in general, the SR channel is used by the terminal to request allocation of radio resources to the base station. However, even when there is a radio resource allocated from the base station, when a predetermined event occurs, the terminal transmits 1 bit information through the SR channel to the base station. By transmitting to can inform the situation of the terminal. Alternatively, the terminal may use the SR channel for transmitting a response to the radio resource allocation message transmitted from the base station. For these embodiments, in addition to the SR channel, another physical channel configured of at least 1 bit or more may be configured.

One example of the predetermined event is a situation in which there is no data to be transmitted to the base station in the buffer of the terminal when there is a radio resource allocated to the terminal.

Another example of the predetermined event is a situation where there is a bearer in which the quality of service (QoS) is not satisfied in the terminal. For example, a Maximum Bit Rate (MBR) or a PBR (Prioritized Bit Rate) may be set for each logical channel of the terminal. When the MBR or PBR set for a specific bearer is not satisfied, the terminal uses an SR channel. You can report it. MBR means the maximum amount of data that can be transmitted to the lower layer for each transmission time interval (TTI) for each logical channel, and PBR means the minimum amount of data.

Another example of the predetermined event is a situation in which data of a specific logical channel designated by the base station arrives in a buffer. That is, when data of a specific logical channel designated by the base station occurs in the terminal, the terminal may inform the base station through an SR channel.

Another embodiment of the present invention will be described as follows. Since the SR channel is a channel consisting of 1 bit, the UE does not request the allocation of radio resources through the SR channel and an error occurs during the transmission even when the UE does not transmit the BSR. It can be mistaken that 1 bit information is received. In this case, the base station transmits a message for allocating an uplink radio resource to the terminal. Upon receiving a radio resource allocation message from the base station, the terminal transmits a BSR using the allocated radio resource. On the other hand, if there is an extra space in the MAC PDU including the BSR, the UE may transmit the RRC measurement report (RRC measurement report) or RLC status report (RLC status report) in the MAC PDU to the base station.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

In this document, embodiments of the present invention have been described based on data transmission / reception relations between a terminal and a base station. Certain operations described in this document as being performed by a base station may in some cases be performed by an upper node thereof. That is, it is obvious that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station may be performed by the base station or other network nodes other than the base station. A 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the term "terminal" may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), and the like.

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of a hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

1 illustrates an example of a physical channel structure used in an E-UMTS system.

2 is a view for explaining a general method for transmitting data in the E-UMTS.

3 is a diagram illustrating a network structure of an E-UMTS.

4 is a schematic diagram of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN).

5A and 5B illustrate a structure of a radio interface protocol between a UE and an E-UTRAN. FIG. 5A is a control plane protocol configuration diagram and FIG. 5B is a user plane protocol configuration diagram. .

6 is a process flow diagram of an embodiment of the present invention.

7 is a process flow diagram according to another embodiment of the present invention.

8A and 8B illustrate data formats of a short BSR and a long BSR, respectively.

9A to 9C are diagrams for describing the format of a MAC PDU.

10 is a flowchart of a procedure according to another embodiment of the present invention.

11 is a process flow diagram according to another embodiment of the present invention.

Claims (16)

A buffer status report method in a terminal of a wireless communication system, Transmitting a first buffer status report indicating a buffer status of a terminal to a base station; And Triggering a transmission procedure of the second buffer status report when the allocation information indicating the allocation of radio resources for the transmission of the uplink data is not received until a predetermined time elapses after the transmission of the first buffer status report ( a buffer status reporting method. The method of claim 1, The allocation information is a buffer status reporting method, characterized in that the information for allocating radio resources associated with the initial transmission of the uplink data. The method of claim 1, And a timer for checking the elapse of the predetermined time is driven from a time point of receiving an acknowledgment signal (ACK) for the first buffer status report from the base station. The method of claim 1, wherein the triggering step, Receiving an uplink channel resource for transmitting the second buffer status report; And transmitting the second buffer status report to the base station through the uplink channel resource. The method of claim 4, wherein And a scheduling request (SR) information or a random access process to receive an uplink channel resource for transmission of the second buffer status report. The method of claim 1, After triggering the transmission procedure of the second buffer status report, transmitting scheduling request (SR) information to the base station. The method of claim 6, And a random access process is performed when uplink radio resources are not allocated from the base station even after transmitting the scheduling request information repeatedly for a predetermined number of times. The method of claim 7, wherein And transmitting the scheduling request information when the uplink radio resource is allocated from the base station while transmitting the scheduling request information repeatedly as many times as the predetermined number of times. The method of claim 7, wherein The information indicating the predetermined number of times is included in system information or RRC (Radio Resource Control) message, characterized in that received by the terminal, the buffer status reporting method. The method of claim 1, And the first buffer status report is included in a specific control element of a MAC protocol data unit (MAC PDU) and transmitted. In the buffer status reporting method in the terminal of the wireless communication system, Triggering a buffer status reporting procedure when a preset predetermined condition is satisfied; And Transmitting a scheduling request (SR) information to a base station in order to receive an uplink channel resource for the buffer status report when there is no allocated uplink radio resource when the buffer status report procedure is triggered. Buffer status reporting method. The method of claim 11, The predetermined condition is satisfied when the timer for buffer status reporting expires and the terminal stores data to be transmitted. The method of claim 11, And a random access process is performed when uplink radio resources are not allocated from the base station even after transmitting the scheduling request information repeatedly for a predetermined number of times. The method of claim 13, And transmitting the scheduling request information when the uplink radio resource is allocated from the base station while transmitting the scheduling request information repeatedly as many times as the predetermined number of times. The method of claim 13, The information indicating the predetermined number of times is included in the system information or RRC message is received by the terminal, characterized in that the buffer status reporting method. The method of claim 11, The buffer status report, characterized in that the buffer status report method characterized in that the transmission is included in a specific control element of the MAC PDU.

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