Method for transmitting scheduling request effectively in wireless communication system

A method for efficiently transmitting a scheduling request in a mobile communication system

The present invention relates to a method for transmitting and receiving data between a base station and a terminal in an LTE system (Long Term Evolution System). In particular, when a terminal requests allocation of radio resources to a base station, while performing a RACH process, its own wireless terminal The present invention relates to a method of increasing radio resource waste and efficiency by appropriately selecting radio resources when radio resources are allocated through identifiers.

1 is a diagram illustrating a network structure of an Evolved Universal Mobile Telecommunications System (E-UMTS), which is a mobile communication system to which the prior art and the present invention are applied. The E-UMTS system is an evolved system from the existing UMTS system, and basic standardization work is currently underway in 3GPP. The E-UMTS system may be referred to as a Long Term Evolution (LTE) system.

The E-UMTS network can be largely divided into E-UTRAN and CN. E-UTRAN consists of a terminal (User Equipment; hereafter abbreviated as UE), a base station (hereinafter abbreviated as eNode B), a Serving Gateway located at the end of the network and connected to an external network (Serving Gateway; hereafter abbreviated as S-GW), and a terminal It consists of a Mobility Management Entity (MME) that manages the mobility of One or more cells may exist in one eNode B.

2 and 3 show the structure of a radio interface protocol between a terminal and a base station based on the 3GPP radio access network standard. The wireless interface protocol is horizontally composed of a physical layer, a data link layer, and a network layer, and vertically a user plane for data information transmission and control. It is divided into a control plane for signal transmission. The protocol layers are L1 (Layer 1), L2 (Layer 2), and L3 (Layer 3) based on the lower three layers of the Open System Interconnection (OSI) reference model widely known in communication systems. can be divided into

Hereinafter, each layer of the radio protocol control plane of FIG. 2 and the radio protocol user plane of FIG. 3 will be described.

The first layer, the physical layer, provides an information transfer service to the upper layer 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 this transport channel. In addition, data moves between different physical layers, that is, between the physical layers of the transmitting side and the receiving side through a physical channel.

The second layer's Medium Access Control (hereinafter abbreviated as MAC) provides a service to an upper layer, the Radio Link Control layer, through a logical channel. The second layer of the radio link control (Radio Link Control; hereinafter abbreviated as RLC) layer supports reliable data transmission. The PDCP layer of the second layer performs header compression (Header Compression) function. In addition, the PDCP layer is used to perform encryption of C-plane data, for example, an RRC message. PDCP also performs encryption of U-plane data.

The radio resource control (RRC) layer located at the bottom of the third layer is defined only in the control plane, and the configuration and resetting (Re) of the radio bearer (Radio Bearer; RB) -configuration) and release (Release) are responsible for the control of logical channels, transport channels and physical channels. In this case, the RB means a service provided by the second layer for data transfer between the UE and the E-UTRAN.

Hereinafter, the RACH (Random Access Channel) will be described in detail. The RACH channel is used to transmit short-length data uplink, particularly when there is a signaling message or user data to be transmitted uplink by a terminal to which a dedicated radio resource is not allocated. Alternatively, it may be used when the base station instructs the terminal to perform the RACH process.

The following is a description of a random access procedure provided by the LTE system. The random access procedure provided by the LTE system is divided into a contention based random access procedure and a non-contention based random access procedure. A distinction between the contention-based random access procedure and the contention-free random access procedure is determined according to whether the UE directly or the base station selects the random access preamble used in the random access procedure.

In the contention-free random access process, the terminal uses a random access preamble directly allocated to the base station by the base station. Accordingly, when the base station allocates the specific random access preamble to only the terminal, only the terminal uses the random access preamble, and other terminals do not use the random access preamble. Accordingly, since a 1:1 relationship is established between the random access preamble and the UE using the random access preamble, it can be said that there is no collision. In this case, since the base station can know the terminal that has transmitted the random access preamble as soon as it receives the random access preamble, it can be said to be efficient.

Conversely, in the contention-based random access process, since the UE randomly selects and transmits the random access preambles that can be used, there is a possibility that a plurality of UEs always use the same random access preamble. Therefore, even if the base station receives a specific random access preamble, it cannot know which terminal has transmitted the random access preamble.

In general, the UE may perform a random access procedure in the following cases. 1) When the terminal does not have an RRC connection with the base station and makes initial access 2) When the terminal accesses the target cell for the first time during the handover process 3) When requested by the command of the base station 4 ) When uplink time synchronization is not met or data to uplink occurs in a situation in which a designated radio resource used for requesting a radio resource is not allocated 5) Radio link failure or handover In case of recovery process in case of handover failure.

Based on the above description, FIG. 4 shows an operation process of a terminal and a base station in a contention-based random access process.

First, in contention-based random access, the UE randomly selects one random access preamble from a set of random access preambles indicated through system information or a handover command, and transmits the random access preamble. A PRACH resource is selected and transmitted to the base station. (Step 1) The preamble at this time is called RACH MSG 1.

After the terminal transmits the random access preamble as described above, the terminal attempts to receive a response to its random access preamble within the random access response reception window indicated through system information or a handover command (step 2). In more detail, the random access response information is transmitted in the form of a MAC PDU, and the MAC PDU may be transmitted through a Physical Downlink Shared Channel (PDSCH). In addition, a Physical Downlink Control Channel (PDCCH) is also transmitted so that the UE can properly receive information transmitted through the PDSCH. That is, the PDCCH may include information of a terminal that should receive the PDSCH, frequency and time information of radio resources of the PDSCH, and a transmission format of the PDSCH. Here, if the terminal succeeds in receiving the PDCCH coming to it, it appropriately receives a random access response transmitted to the PDSCH according to the information of the PDCCH. And, the random access response includes a random access preamble identifier (ID), UL Grant (uplink radio resource), Temporary C-RNTI (temporary cell identifier), and Time Alignment Command (time synchronization correction value). The reason why the random access preamble identifier is needed is that one random access response may include random access response information for one or more terminals, so the UL Grant, Temporary C-RNTI, and Time Alignment Command information is valid for which terminal. it is to inform The random access preamble identifier coincides with the random access preamble selected by the user in step 1.

Here, when the terminal receives a random access response valid for it, it processes information included in the random access response, respectively. That is, the terminal applies the Time Alignment Command and stores the Temporary C-RNTI. In addition, data stored in the buffer of the terminal or newly generated data is transmitted to the base station by using the UL grant (step 3). In this case, the identifier of the UE must be necessarily included in the data included in the UL Grant (hereinafter also referred to as message 3). This is because, in the contention-based random access procedure, the base station cannot determine which UEs perform the random access procedure, but the UE needs to be identified in order to resolve the collision later. Here, there are two methods for including the identifier of the terminal. In the first method, if the terminal already has a valid cell identifier allocated from the corresponding cell before the random access procedure, the terminal transmits its own cell identifier through the UL Grant. On the other hand, if a valid cell identifier has not been allocated before the random access procedure, the terminal transmits it including its own unique identifier (eg, S-TMSI or Random Id). In general, the unique identifier is longer than the cell identifier. In step 3, if the terminal transmits data through the UL grant, the terminal starts a contention resolution timer.

After the terminal transmits data including its identifier through the UL grant included in the random access response, the terminal waits for an instruction from the base station to resolve the collision. That is, it attempts to receive a PDCCH to receive a specific message (step 4). Here, there are two methods for receiving the PDCCH. As mentioned above, if the identifier transmitted through the UL Grant is a cell identifier, the PDCCH is attempted to be received using the cell identifier. If the identifier is a unique identifier, it is included in the random access response. It attempts to receive the PDCCH by using the Temporary C-RNTI. After that, in the former case, if the PDCCH (hereinafter referred to as message 4) is received through its cell identifier before the collision resolution timer expires, the terminal determines that the random access process is normally performed, and random access Terminate the process. In the latter case, if the PDCCH is received through the temporary cell identifier before the collision resolution timer expires, data transmitted by the PDSCH indicated by the PDCCH (hereinafter referred to as message 4) is checked. If the content of the data includes its own unique identifier, the terminal determines that the random access process has been normally performed, and ends the random access process. Here, the message or MAC PDU received in this fourth step is often referred to as RACH MSG 4.

The following describes a method for the terminal to receive downlink data in the LTE system. 5 is an exemplary diagram illustrating radio resource allocation according to the prior art.

In the downlink direction, the physical channel is largely divided into two, which are a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH). The PDCCH is not directly related to transmission of user data, and control information necessary for operating a physical channel is transmitted. In the simplest explanation, it can be said that the PDCCH is used to control other physical channels. In particular, the PDCCH is used for transmission of information necessary for the UE to receive the PDSCH. At a specific point in time, information such as data transmitted using a specific frequency band, for which terminal, what size data is transmitted, and the like is transmitted through the PDCCH. Therefore, each terminal receives the PDCCH at a specific TTI, checks whether data to be received is transmitted through the PDCCH, and if it informs that the data to be received is transmitted, the frequency indicated by the PDCCH The PDSCH is additionally received using such information. To which terminal (one or a plurality of terminals) PDSCH data is transmitted, and information on how the terminals should receive and decode PDSCH data, the physical channel PDCCH (Physical Downlink Control Channel) It can be said that it is included and transmitted.

For example, in a specific subframe, radio resource information called A (eg, frequency location) and transmission format information called B (eg, transport block size, modulation and coding information, etc.) are RNTI (Radio Network Assume that it is CRC masked with Temporary Identity) and transmitted through PDCCH. One or more terminals in a corresponding cell monitor the PDCCH using their RNTI information. won't Accordingly, the terminal receives data by decoding the PDSCH using the transmission format information B and radio resource information A. On the other hand, in the above assumption, a CRC error is generated when the PDCCH is decoded in a UE that does not have an RNTI C. Therefore, the terminal does not receive the PDSCH.

In the above process, through each PDCCH, a Radio Network Temporary Identifier (RNTI) is transmitted in order to inform which terminals are allocated radio resources. The RNTI includes a dedicated RNTI and a common RNTI. A dedicated RNTI is allocated to one terminal and is used for transmitting and receiving data corresponding to the terminal. The dedicated RNTI is allocated only to a terminal whose information is registered in the base station. Conversely, the common RNTI is used for transmission of information commonly applied to a plurality of terminals such as system information or when terminals not assigned a dedicated RNTI because information is not registered with the base station exchange data with the base station.

As mentioned above, the two axes constituting the E-UTRAN are the base station and the terminal. A radio resource in one cell consists of an uplink radio resource and a downlink radio resource. The base station is responsible for allocating and controlling the uplink radio resource and the downlink radio resource of the cell. That is, the base station determines which radio resource is used by which terminal at any moment. For example, after 3.2 seconds, the base station may determine to allocate frequencies from 100Mhz to 101Mhz to user No. 1 for downlink data transmission for 0.2 seconds. And, after the base station makes this decision, the base station notifies the corresponding terminal of this fact so that the terminal can receive downlink data. Similarly, the base station determines when and when which terminal uses which radio resource to transmit data uplink, and the base station notifies the terminal of this decision, so that the terminal transmits data using the radio resource during the time. do it

Unlike the prior art, the base station dynamically manages radio resources in this way enables efficient use of radio resources. The prior art allows one terminal to continuously use one radio resource while a call is connected. This is irrational, especially considering that many services are based on IP packets these days. This is because most packet services do not continuously generate packets during the call connection time, but there are many sections in which nothing is transmitted during the call. Even so, it is inefficient to continuously allocate radio resources to one terminal. In order to solve this problem, the E-UTRAN system uses a method of allocating radio resources to the terminal in the above manner only when the terminal is needed and only while there is service data.

More specifically, in the LTE system, in order to efficiently use radio resources, the base station needs to know what data and how much data each user wants to transmit. In the case of downlink data, this downlink data is transferred from the access gateway to the base station. Thus, the base station knows how much data should be delivered on the downlink to each user. Conversely, in the case of uplink data, the base station cannot know how much uplink radio resources each terminal requires unless the terminal directly informs the base station of information on data that it intends to transmit in the uplink. Therefore, in order for the base station to properly allocate uplink radio resources to the terminals, each terminal must provide information necessary for the base station to schedule radio resources to the base station.

To this end, when the terminal has data to be transmitted, the terminal notifies the base station, and the base station transmits a radio resource allocation message to the terminal based on this information.

In the above process, that is, when the terminal notifies the base station when there is data to be transmitted, the terminal informs the base station of the amount of data accumulated in its buffer. This is called Buffer Status Report (BSR).

However, the buffer status information is generated in the form of a MAC Control Element (MAC CE) and is included in a MAC Protocol Data Unit (PDU) and transmitted from the terminal to the base station. That is, an uplink radio resource is also required to transmit buffer status information. This means that uplink radio resource allocation request information for transmitting buffer status information should be transmitted. When the buffer status information is generated, if there is an allocated uplink radio resource, the terminal immediately transmits the buffer status information using the uplink radio resource. However, when the buffer status information is generated, if there is no allocated uplink radio resource, the UE performs a resource allocation request (SR procedure: Scheduling Request Procedure) procedure.

There are two main types of SR procedures: a method using a Dedicated Scheduling Request (D-SR) channel configured for a Physical Uplink Control Channel (PUCCH) resource, and a method using a Random Access Channel (RACH) procedure. That is, when the SR process is triggered, the terminal sends a radio resource allocation request using the D-SR channel if the D-SR channel is assigned. If the D-SR channel is not assigned, the terminal performs the RACH process. Start. When the D-SR channel is used, a resource request allocation signal is transmitted in an uplink direction through the D-SR channel.

The SR process continues until the UE is allocated a UL-SCH resource.

In the above process, the buffer status information transmitted by the terminal notifies the amount of the buffer for each logical channel group (LCG), not the information on the amount of the buffer for each logical channel. That is, the amount of buffer is calculated for each group designated by the base station. A maximum of 4 LCGs are defined for one UE. In the above process, there are two types of buffer status information. One is Long Buffer Status Report (Long BSR) and the other is Short Buffer Status Report (Short BSR). Long BSR includes information about the amount of buffer for all four LCGs, and Short BSR includes information about the amount of buffer for only one LCG.

<p>The conventional radio resource allocation request method described above has the following problems. In general, there are a plurality of terminals in one cell, and the base station allocates radio resources from the terminal having the higher priority and the channel having the higher priority. Accordingly, in some cases, the base station may not allocate radio resources to the terminal even though it has received a radio resource request message or buffer status information from a specific terminal. In this case, if the terminal continuously sends radio resource allocation requests, this causes waste of uplink radio resources and only interference of radio resources. In addition, in the above case, the base station may directly allocate radio resources to the terminal while the terminal is performing the RACH process. For example, in a state where the second step of the RACH process is completed, the terminal may be allocated a radio resource from the base station using its dedicated identifier. However, the second message of the RACH process also has information on allocating radio resources to the terminal that has performed the RACH process. In this case, if the terminal continuously performs the RACH process, radio resources allocated using the dedicated identifier are wasted. In addition, the D-SR channel is effective only when the terminal is synchronized in the uplink (Synchronized). That is, if the terminal does not synchronize in the uplink direction, no matter how the terminal uses the D-SR channel, the base station cannot properly receive the radio resource allocation request from the terminal. In this case, if the terminal continues to transmit the radio resource allocation request without considering such a situation, only radio resource interference is caused.</p>

<p>Accordingly, it is an object of the present invention to provide a method for efficiently requesting radio resources from a base station while minimizing radio resource interference.</p><p>In order to solve the problem of the present invention as described above, there is provided a method of processing a scheduling request (SR) in a wireless communication system according to the present invention, the method comprising: determining whether the scheduling request is triggered; transmitting the scheduling request on the uplink control channel if an uplink control channel is configured for transmitting the scheduling request or if an uplink control channel is configured for transmitting the scheduling request If not, initiating a random access channel procedure (random access channel procedure); monitoring a downlink control channel; determining whether an identifier of the terminal has been received through the downlink control channel; And if it is determined that the identifier of the terminal has been received, it characterized in that it comprises the step of stopping the scheduling request triggering (triggering).</p><p>Preferably, the uplink control channel is a Physical Uplink Control Channel (PUCCH).</p><p>Preferably, the downlink control channel is a Physical Downlink Control Channel (PDCCH).</p><p>Preferably, the step of transmitting the scheduling request over the uplink control channel or the step of initiating the random access channel process is characterized in that it is performed when it is determined that the scheduling request is triggered.</p><p>Preferably, the identifier of the terminal is characterized in that the Cell-Radio Network Temporary Identifier (C-RNTI).</p><p>Preferably, if it is determined that the identifier of the terminal has not been received, the scheduling request triggering is continuously performed.</p><p>In addition, in order to solve the problem of the present invention as described above, as a method of performing a random access channel (RACH) procedure in a wireless communication system according to the present invention, a random access channel preamble is transmitted. step of; monitoring a downlink control channel after the RACH preamble is transmitted; In the step of determining whether an uplink resource is received together with an identifier of a terminal through the downlink control channel, the uplink resource is used to transmit next scheduled data; and stopping the random access channel process if it is determined that the uplink resource is received together with the identifier of the terminal.</p><p>Preferably, the downlink control channel is a Physical Downlink Control Channel (PDCCH).</p><p>Preferably, the uplink allocation resource is characterized in that the UL-GRANT.</p><p>Preferably, the identifier of the terminal is characterized in that the Cell-Radio Network Temporary Identifier (C-RNTI).</p><p>Preferably, if it is determined that the uplink allocation resource is not received together with the identifier of the terminal, the RACH process is continuously performed.</p><p>Preferably, in the step of receiving a response message in response to the transmitted RACH preamble, the response message further comprises that the response message includes another always-allocated resource.</p><p>Preferably, if it is determined that the uplink resource is received together with the identifier of the terminal, the other uplink resource is discarded.</p>

<p>The present invention provides a method for effectively using radio resources when the terminal performs a buffer status information or scheduling request (SR) process to the base station, thereby enabling the terminal to more quickly and accurately receive radio resources from the base station.</p>

1 is a network structure of E-UMTS, which is a mobile communication system to which the prior art and the present invention are applied. 2 is a control plane structure of a radio interface protocol between a terminal and a UMTS Terrestrial Radio Access Network (UTRAN) based on the 3GPP radio access network standard. 3 is a user plane structure of a radio interface protocol between a terminal and a UMTS Terrestrial Radio Access Network (UTRAN) based on the 3GPP radio access network standard. 4 is an exemplary diagram illustrating a contention-based random access process. 5 is an exemplary diagram illustrating radio resource allocation according to the prior art. 6 is an exemplary diagram illustrating an operation method used for a terminal to transmit buffer status information to a base station according to the present invention. 7 is an exemplary diagram illustrating a method for a terminal to transmit buffer status information to a base station in a random access process according to the present invention;

The present invention is applied to 3GPP communication technology, in particular, a UMTS (Universal Mobile Telecommunications System) system, a communication device, and a communication method. However, the present invention is not limited thereto, and may be applied to all wired and wireless communications to which the technical spirit of the present invention can be applied.

A basic concept of the present invention is a method for processing a scheduling request (SR) in a wireless communication system, the method comprising: determining whether the scheduling request is triggered; transmitting the scheduling request on the uplink control channel if an uplink control channel is configured for transmitting the scheduling request or if an uplink control channel is configured for transmitting the scheduling request If not, initiating a random access channel procedure (random access channel procedure); monitoring a downlink control channel; determining whether an identifier of the terminal has been received through the downlink control channel; And if it is determined that the identifier of the terminal has been received, we propose a method of processing a scheduling request (SR) in a wireless communication system, comprising the step of stopping triggering of the scheduling request and performing this method We propose a wireless mobile communication terminal that can

Also according to the present invention, there is provided a method of performing a random access channel (RACH) procedure in a wireless communication system, the method comprising: transmitting a random access channel preamble (RACH preamble); monitoring a downlink control channel after the RACH preamble is transmitted; In the step of determining whether an uplink resource is received together with an identifier of a terminal through the downlink control channel, the uplink resource is used to transmit next scheduled data; and stopping the random access channel process if it is determined that the uplink resource is received together with the identifier of the terminal. We propose a method for performing , and a wireless mobile communication terminal capable of performing such a method.

Hereinafter, the configuration and operation of embodiments according to the present invention will be described with reference to the accompanying drawings.

As described above, the present invention intends to propose a method for efficiently requesting radio resources from a base station while minimizing interference of radio resources. To this end, in the present invention, when the terminal requests a radio resource from the base station using the D-SR channel, the terminal sends the radio resource request to the base station using the D-SR channel for a predetermined number of times or for a predetermined time. If the uplink radio resource is not allocated, the radio resource request process using the D-SR channel is no longer performed. Preferably, in this process, the terminal transitions to the radio resource request process using the RACH process. In the above process, if the radio resource is allocated to the base station while the D-SR channel is not used for a predetermined number of times, the terminal immediately stops the radio resource request process. And in this case, cancel the setting of the D-SR channel and do not use it any more.

In addition, in the present invention, in order for the terminal to efficiently transmit buffer status information to the base station, when data newly arrives on a certain logical channel, the terminal considers the priority of the logical channel and the priorities of other logical channels, It is proposed to decide whether to transmit status information or not.

Specifically, the first operating method (Approach 1) according to the present invention is as follows. For a logical channel in which there was no data in the buffer previously, when data newly arrives in the logical channel, the terminal checks the priority (A) of the logical channel. In addition, the terminal checks the logical channel group to which the logical channels belong with respect to all other logical channels having data in the buffer. For each logical channel belonging to the identified logical channel group, the priority (B) of each logical channel is checked regardless of whether there is data in the buffer of the logical channels. And, the terminal compares the priorities (A) and the priorities (B), and when the priority (A) is higher than any priority (B), it triggers the buffer status information and transmits it to the base station . Preferably, in this process, only the priorities of logical channels having the highest priority in the logical channel groups may be considered and compared.

Specifically, the second operation method (Approach 2) according to the present invention is as follows. For a logical channel in which there was no data in the buffer previously, when data newly arrives in the logical channel, the terminal checks the priority (A) of the logical channel. Then, the terminal checks the priority (B) of each of the logical channels for all other logical channels having data in the buffer. And, the terminal compares the priorities (A) and the priorities (B), and when the priority (A) is higher than any other priority (B), it triggers the buffer status information and transmits it to the base station .

The difference in results by the first operation method and the second operation method is illustrated in FIG. 6 .

That is, according to the first operation method, if data newly arrives in the first logical channel, the priority of the first logical channel is not higher than that of any other logical channel (the fourth logical channel), so the buffer state Does not trigger information. However, according to the second operation method, if data newly arrives in the first logical channel, the priority of the first logical channel is the priority of all other logical channels (third logical channel) having data in the buffer. higher, so it triggers buffer status information.

Specifically, the third operation method (Approach 3) according to the present invention is as follows. For a logical channel that previously had no data in the buffer, when data newly arrives in the logical channel, the terminal checks the priority (A) of the logical channel and also identifies the logical channel group to which the logical channel belongs do. Then, the terminal checks the logical channels that have data in the buffer among the logical channels belonging to the logical channel group. When buffer information for the logical channel group or logical channels has already been delivered to the base station, the terminal does not trigger new buffer status information.

Specifically, the fourth operation method (Approach 4) according to the present invention is as follows. For a logical channel that previously had no data in the buffer, when data newly arrives in the logical channel, the terminal checks the priority (A) of the logical channel and also identifies the logical channel group to which the logical channel belongs do. Then, the terminal checks the logical channels that have data in the buffer among the logical channels belonging to the logical channel group. When buffer information for the logical channel group or logical channels has already been delivered to the base station, the terminal checks whether the amount of buffer newly accumulated in the logical channel group exceeds a reference value after the buffer status information is transferred to the base station. Check and trigger new buffer status information only when the reference value is exceeded.

Specifically, the fifth operation method (Approach 5) according to the present invention is as follows. For a logical channel that previously had no data in the buffer, when data newly arrives in the logical channel, the terminal checks the priority (A) of the logical channel and also checks which logical channel group the logical channel belongs to do. Then, the terminal checks the priority (B) of the logical channels having data in the buffer among the logical channels belonging to the logical channel group. When the priority (A) is higher than the priority (B), the UE triggers new buffer status information.

Specifically, the sixth operation method (Approach 6) according to the present invention is as follows. For a logical channel that previously had no data in the buffer, when data newly arrives in the logical channel, the terminal checks the priority (A) of the logical channel and also checks which logical channel group the logical channel belongs to do. And the terminal checks the priority (B) of each logical channel from among all the logical channels belonging to the logical channel group, regardless of whether or not data is stored in the buffer. When the priority (A) is higher than the priority (B), the UE triggers new buffer status information.

Specifically, the seventh operation method (Approach 7) according to the present invention is as follows. For a logical channel that previously had no data in the buffer, when data newly arrives in the logical channel, the terminal determines the priority ( A) is checked. For each of the other configured logical channel groups, the priority (B) of the logical channel having the highest priority among logical channels belonging to each logical channel group is checked. And, compared with the priorities (A) and the priorities (B), the terminal triggers the buffer status information and transmits the buffer status information to the base station when the priority (A) is higher than any other priority (B). Preferably, in this process, logical channels without data can be excluded from comparison.

In the above process, when the buffer status information for different logical channel groups is the same and only the buffer status information for a specific logical channel group is changed, the UE can use the Short BSR.

In addition, in the present invention, when the SR process starts, the terminal starts the RACH process when there is no D-SR channel allocated to the terminal in order to efficiently transmit the buffer status information to the base station. In the second step of the RACH process, the UE is allocated a UL-SCH resource to be used in the third step. However, in the case of the contention-based RACH process, until the contention resolution is successfully completed in the fourth step, the terminal cannot know whether the data it transmits in the third step has been successfully delivered to the base station. Therefore, it is proposed that the terminal that has started the SR process does not stop the SR process even if it is allocated radio resources in the uplink direction through the third step of the RACH process. 7 is an exemplary diagram illustrating a method for a terminal to transmit buffer status information to a base station in a random access process according to the present invention. That is, as shown in FIG. 7, only when the UE receives a GRANT using its C-RNTI in the fourth step of the RACH, it is considered that the SR process is successfully completed. That is, only when the C-RNTI of the asset is received through the PDCCH (Physical Downlink Control Channel), it is considered that the SR process has been successfully completed and the SR process is stopped. If the UE does not receive a GRANT using its C-RNTI in the fourth step of the RACH, the SR process is continuously executed without stopping.

Although the base station recognizes that a specific terminal has data to transmit according to the amount of usable radio resources present in one cell or a scheduling algorithm used by the eNB (e-NodeB), the base station is the terminal In some cases, radio resources are not allocated to Therefore, in this case, the UE hastily transmits another buffer status information or performs the SR process, resulting in waste of radio resources. Or, even if the SR process or the process of transmitting buffer status information is being performed, it should be able to properly stop. Accordingly, in the present invention, when the terminal is allocated a dedicated radio resource from the base station while performing the RACH process due to buffer status information transmission or SR process, that is, when the terminal is allocated an uplink radio resource through C-RNTI , the UE proposes to immediately stop the RACH process. In addition, in the present invention, when the SR process is started, when the dedicated radio resource is allocated from the base station, i.e., until the uplink radio resource is allocated through the C-RNTI, it is suggested that the terminal continue to perform the SR process. do. Preferably, when the UE is allocated a radio resource to be used in the third stage of the RACH in the second stage of the RACH, and at the same time, when the radio resource is allocated through the PDCCH through its C-RNTI, it is allocated through the C-RNTI It is suggested to use the received radio resource. At this time, if necessary, the BSR is transmitted using the radio resource. Preferably, when the UE is allocated radio resources to be used in the third stage of the RACH in the second stage of the RACH, and at the same time is allocated radio resources through the PDCCH through its C-RNTI, the second stage of the RACH process It is proposed to use the radio resource allocated by At this time, if necessary, the BSR is transmitted using the radio resource.

Hereinafter, a terminal according to the present invention will be described.

The terminal according to the present invention includes all types of terminals capable of using a service capable of exchanging data with each other on the radio. That is, the terminal according to the present invention is a mobile communication terminal capable of using a wireless communication service (eg, user equipment (UE), mobile phone, cellular phone, DMB phone, DVB-H phone, PDA phone, PTT phone, etc.) It is a generic term that includes laptops, laptop computers, digital TVs, GPS navigation, portable game consoles, MP3 players and other consumer electronics.

The terminal according to the present invention may include a basic hardware configuration (transmission/reception unit, processing unit or control unit, storage unit, etc.) necessary to perform functions and operations for more efficient radio resource use exemplified in the present invention.

The method according to the present invention described so far may be implemented in software, hardware, or a combination thereof. For example, the method according to the present invention may be stored in a storage medium (eg, an internal memory of a mobile terminal or base station, flash memory, hard disk, etc.) and a processor (eg, a mobile terminal or a base station) may be implemented as codes or instructions in a software program that may be executed by an internal microprocessor).

As mentioned above, although the present invention has been described with reference to the embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. . Accordingly, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.