WO2015170943A1 - Method and apparatus for network selecting and configuring terminal that is to record and report mbms related measurement information, and for terminal reporting the recorded information to base station in mobile communication system - Google Patents

Abstract

The present invention relates to a method and an apparatus for selecting and configuring a terminal that is to record and report MBMS related measurement information, and for reporting the recorded information to a base station using the selected terminal in a mobile communication system. More specifically, the present invention relates to the technical technology for providing a method and an apparatus for a network in a mobile communication system to select according to a predetermined rule a terminal that is to gather information required for optimising an MBMS service area and for configuring the selected terminal to record and report the information.

Description

Method and apparatus for selecting and setting a terminal to record and report MBMS related measurement information in a mobile communication system and reporting the recorded information to a base station by a terminal

The present invention relates to a method and apparatus for selecting and setting a terminal to record and report MBMS related measurement information in a mobile communication system, and reporting the recorded information to a base station. More specifically, in the wireless communication system, a network and a method according to a predetermined rule, to select the terminal to collect the information required to optimize the MBMS service area and to set to record and report the information to the selected terminal It relates to the technology to provide.

In general, a mobile communication system has been developed for the purpose of providing communication while securing user mobility. Such a mobile communication system has reached a stage capable of providing high-speed data communication service as well as voice communication due to the rapid development of technology.

Recently, one of the next generation mobile communication systems, 3GPP is working on the specification of Long Term Evolution (LTE). LTE is a technology that enables high-speed packet-based communication with a transmission rate of up to 100 Mbps, which is higher than the data rate that is generally provided. To this end, various measures are discussed. For example, a method of simplifying the structure of a network to reduce the number of nodes located on a communication path, or approaching wireless protocols as close as possible to a wireless channel is under discussion.

On the other hand, the data service, unlike the voice service, is determined according to the amount of data to be transmitted and the channel conditions and resources that can be allocated. Therefore, in a wireless communication system such as a mobile communication system, management such as allocating transmission resources is performed in consideration of the amount of resources to be transmitted by the scheduler, the situation of the channel and the amount of data. This is the same in LTE, one of the next generation mobile communication systems, and a scheduler located in a base station manages and allocates radio transmission resources.

Recently, a discussion about an advanced LTE communication system (LTE-Advanced, LTE-A), which improves transmission speed by incorporating various new technologies into an LTE communication system, has been in full swing. In the advanced LTE-A system, the improvement of the multicast multimedia broadcasting service (MBMS: Multimedia Broadcast Multicast Service, hereinafter referred to as MBMS) is also included. MBMS is a broadcast service provided through an LTE system. Operators must optimize the service area for MBMS service as well as unicast communication. To do this, the existing drive test can be performed to optimize cell and system settings based on the collected measurement information. . However, it increases wireless network optimization costs and operating costs, and takes a lot of time. Therefore, researches for minimizing the drive test and improving the analysis process and the manual configuration of the wireless environment are being conducted under the name of the Minimization of Drive Test (MDT). This technique can be utilized to optimize the service area of MBMS service.

The present invention is to solve the problem of collecting measurement information that is less relevant to MBMS in the above-described MDT, the network selects and selects a terminal to collect the information required to optimize the MBMS service area according to a predetermined rule The present invention relates to a method and an apparatus for enabling a terminal to record and report the information.

In the mobile communication system of the present invention for solving the above problems, the method for measuring a Minimization of Drive Test (MDT) of a base station includes transmitting an MDT measurement setup message to at least one terminal and MDT measurement result from the at least one terminal. Including the step of receiving, The MDT measurement configuration message, characterized in that transmitted through the control channel that can be received by the at least one terminal.

In addition, in the mobile communication system of the present invention, the base station for performing the measurement of the Minimization of Drive Test (MDT) transmits an MDT measurement setup message to a transceiver for performing data communication and at least one terminal, and measures the MDT from the at least one terminal. And a control unit for receiving a result, wherein the MDT measurement setting message is transmitted through a control channel that can be received by the at least one terminal.

In addition, the method of measuring a Minimization of Drive Test (MDT) of the terminal in the mobile communication system of the present invention, receiving an MDT measurement configuration message instructing to perform the MDT measurement from the base station, the terminal in accordance with the MDT measurement configuration message And measuring the received MBMS signal related information and transmitting the MDT measurement result including the measured MBMS signal related information to the base station.

In addition, in the mobile communication system according to the present invention, the terminal performing the measurement of MDT (Minimization of Drive Test) receives a MDT measurement setup message indicating to perform the MDT measurement from the transceiver, the base station for performing data communication, the MDT measurement And a control unit for measuring MBMS signal related information received by the terminal according to a configuration message and transmitting an MDT measurement result including the measured MBMS signal related information to the base station. .

According to various embodiments of the present disclosure, a message for setting MBMS related measurement may be delivered to at least one terminal.

In addition, according to the present invention, there is an effect that the MBMS-related measurements can be performed by selecting a terminal suitable for MBMS-related measurements.

In addition, according to the present invention, there is an effect that it is possible to adjust the excessive signaling overhead due to frequent retrieval.

1 is a conceptual diagram of MBMS,

2 is a downlink channel mapping diagram used for MBSFN transmission;

3 is a diagram of a downlink frame structure used in an LTE system;

4 is a view for explaining a process for the UE to receive MBSFN,

5 is a conceptual diagram for explaining MDT performance;

6 is a view for explaining the difference between the MDT for the existing MDT and MBMS measurement information,

7 is a view for explaining a method for selecting a terminal to perform the MDT, the network when applying the MCCH / BCCH option,

8 is a view for explaining a process of confirming the user consent of the terminal in the present invention,

9 is a view for explaining a method of transmitting a 1-bit indicator to the base station indicating whether the terminal is currently logged MDT in CONN to prevent frequent retrieval of the MDT measurement information,

FIG. 10 is a diagram for describing a method of sending an availability indicator only when a data amount of MDT measurement information stored by a terminal exceeds a specific threshold;

11 is a diagram illustrating a method in which a terminal does not transmit an availability indicator again for a predetermined time when the terminal transmits an availability indicator to the base station once.

12 is a block diagram showing an internal structure of a base station;

13 is a block diagram illustrating an internal structure of a terminal.

The present invention relates to a method and apparatus for selecting and setting a terminal for recording and reporting a multimedia broadcast multicast service (MBMS) related information in a mobile communication system, and reporting the recorded information to a base station. In the present invention, the network selects a terminal to collect information necessary for optimizing the MBMS service area according to a predetermined rule. The network may be configured to record and report the information to a selected terminal by using a predetermined method. In addition, the present invention proposes an efficient reporting method when considering that the UE continuously records the MBMS measurement information regardless of the standby mode or the connected mode.

Prior to describing the specific technique proposed by the present invention, the existing MBMS and MDT techniques will be described first.

1 is a diagram showing a conceptual diagram of MBMS.

The MBMS service area 100 is a network area composed of a plurality of base stations capable of performing Multimedia Broadcast multicast service Single Frequency Network (MBSFN) transmission.

The MBSFN area 105 is a network area composed of integrated cells for MBSFN transmission, and all cells in the MBSFN area are synchronized with MBSFN transmission.

All cells except MBSFN Area Reserved Cells (110) are used for MBSFN transmission. The MBSFN area reserved cell 110 is a cell that is not used for MBSFN transmission, and may be transmitted for other purposes, but limited transmission power may be allowed for a radio resource allocated for MBSFN transmission.

2 is a diagram illustrating a downlink channel mapping relationship used for MBSFN transmission.

As shown in FIG. 2, the MCH (Multicast Channel) 200 is used between the MAC layer and the physical layer, and the MCH is mapped to the physical multicast channel (PMCH) 205 of the physical layer.

A unicast scheme for transmitting data only to a specific terminal may generally use a physical downlink shared channel (PDSCH).

3 is a diagram illustrating a structure of a downlink frame used in an LTE system.

As shown in FIG. 3, any radio frame 300 consists of ten subframes 305. Here, each subframe is a 'general subframe 310' used for general data transmission and reception and a 'MBSFN (Multimedia Broadcast multicast service Single Frequency Network)' (MBSFN) subframe 315 used for broadcasts. There is a form of.

The difference between the general subframe 310 and the MBSFN subframe 315 is the number of Orthogonal Frequency Division Multiplexing (OFDM) symbols, the length of the cyclic prefix, and the cell-specific reference. differences in one or more of the structure and number of signals, CRS).

On the other hand, MBSFN subframes in Release-8 and Release-9 systems are used only for the purpose of transmitting broadcast or multicast data. However, with the evolution of the system, starting with LTE Rel-10, MBSFN subframes can be used not only for broadcast or multicast but also for unicast purposes.

In LTE, in order to efficiently use a physical downlink shared channel (hereinafter referred to as a PDSCH), each UE is connected to a multi-antenna technology and a transmission mode associated with a reference signal (RS). Set by TM).

Currently, LTE Release-10 includes TM1 to TM9. Each UE has one TM for PDSCH transmission, TM 8 is newly defined in Release-9 and TM 9 is newly defined in Release-10.

In particular, TM 9 supports single user-multi-input multi-output (SU-MIMO) having up to eight ranks. TM 9 supports the transmission of multiple layers, and enables up to eight layers to be transmitted by using a Rel-10 Demodulation Reference Signal (DMRS), hereinafter referred to as DMRS, during demodulation. In addition, the Release-10 DMRS transmits a precoded DMRS, but does not need to inform the receiver of the corresponding precoder index. In addition, in order to support TM # 9, DCI (Downlink Control Information) format 2C is newly defined in Rel-10. Note that terminals before Rel-10 do not attempt decoding in the MBSFN subframe. Therefore, having all terminals try to decode in the MBSFN subframe leads to an upgrade request of the terminal of the previous release.

In the present invention, instead of allowing all terminals to receive unicast data in the MBSFN subframe, the function is applied only to terminals requiring the above-described function, for example, high-speed data communication.

In particular, TM 9 defined in Release-10 is a transmission mode that maximizes transmission efficiency by using multiple antennas. In the present invention, the base station sets the TM 9 to the terminal that needs to increase the data throughput by receiving unicast data in the MBSFN subframe, and only the terminal configured with TM 9 receives the unicast data in the MBSFN subframe. .

On the other hand, for unicast data transmission and reception, the LTE system informs the physical downlink control channel (PDCCH) where data transmission and reception actually occurs, and transmits actual data on the physical downlink shared channel (PDSCH). The terminal should determine whether there is resource allocation information allocated to the terminal on the PDCCH before receiving the actual data.

MBSFN, on the other hand, obtains resource allocation information through a more complicated process. First, the base station informs the terminal of the transmission position of the multicast control channel (MCCH) for each MBSFN area provided by the cell through SIB13 (System Information Block 13), which is broadcast information. The MCCH includes resource allocation information for the MBSFN, and the UE can decode the MCCH to determine the transmission position of the MBSFN subframe.

As described above, the reason why the MBMS provides resource allocation information in a manner different from the conventional unicast is that the MBMS should be available to the UE in the standby mode. Therefore, the transmission position of the control channel MCCH is informed to the broadcast information SIB13. The overall process of receiving the MBMS service will be described with reference to FIG. 4.

4 is a flowchart illustrating a process for the UE to receive MBSFN.

Referring to FIG. 4, in step 405, the terminal 400 receives SIB1 from the base station 403. The SIB1 may include scheduling information for other SIBs. Accordingly, the terminal 400 must receive SIB1 prior to receiving another SIB. In step 410, the terminal 400 receives the SIB2 from the base station 403. The MBSFN subframe configuration list (MBSFN-SubframeConfigList IE) of SIB2 may indicate subframes that can be used for MBSFN transmission purposes. The MBSFN-SubframeConfigList IE may include the MBSFN-SubframeConfig IE and may indicate which subframe of which radio frame can be the MBSFN subframe. [Table 1] below is a configuration table of MBSFN-SubframeConfig IE.

Table 1

Here, a radio frame allocation period ( radioFrameAllocationPeriod) and a radio frame allocation offset ( radioFrameAllocationOffset) are used to indicate a radio frame having an MBSFN subframe, and a radio frame satisfying the formula SFN mod r adioFrameAllocationPeriod = radioFrameAllocationOffset has an MBSFN subframe.

SFN is a system frame number and indicates a radio frame number. SFN ranges from 0 to 1023 and is repeated. SubframeAllocation indicates which subframe is the MBSFN subframe in the radio frame indicated by the above equation. It may be indicated by one radio frame unit or four radio frame units. When using one radio frame unit, oneFrame IE is indicated. The MBSFN subframe may exist among 1, 2, 3, 6, 7, and 8th subframes among a total of 10 subframes in one radio frame. Thus, the oneFrame IE indicates MBSFN subframes among the subframes listed above using 6 bits. When using four radio frame units, fourFrames is directed to IE. Using a total of 24 bits to cover four radio frames, the MBSFN subframe is indicated among the subframes listed above for each radio frame. Therefore, the UE can know the subframe that can be exactly MBSFN subframe using the MBSFN-SubframeConfigList IE.

If the terminal 400 wants to receive the MBSFN, the terminal 400 receives SIB13 from the base station 405 in step 415. The MBSFN area information list ( MBSFN-AreaInfoList IE) of SIB13 may include location information through which MCCH for each MBSFN area provided by the cell is transmitted.

In step 420, the terminal 400 may receive the MCCH using the information received in step 415.

[Table 2] below shows MBSFN-AreaInfoList IE. There is an MCCH corresponding to each MBSFN area, and the MBDFN-AreaInfoList IE includes MCCH scheduling information of all MBSFN areas. MBSFN-AreaInfo IE includes MCCH scheduling and other information. Mbsfn-AreaId is an MBSFN area ID. Non-MBSFNregionLength represents the number of symbols corresponding to the non-MBSFN region among symbols in the MBFSN subframe. The symbol is located at the front of the subframe. The notificationIndicator is used to indicate a PDCCH bit informing the UE of the change of MCCH information. Mcch-Config IE contains MCCH scheduling information. Mcch-RepetitionPeriod and mcch-Offset are used to indicate the position of the frame containing the MCCH. Mcch-ModificationPeriod is a transmission period of the MCCH, and sf-AllocInfo indicates the position of the subframe including the MCCH in the frame including the MCCH. Signaling MCS represents a Modulation and Coding Scheme (MCS) applied to a subframe indicated by sf-AllocInfo and (P) MCH.

TABLE 2

The MBSFNAreaConfiguration IE of the MCCH indicates the location of a resource used for MBSFN transmission.

In step 425, the terminal 400 receives the MBSFN subframe using the information received in step 415. commonSF-Alloc represents a subframe allocated to the MBSFN area. commonSF-AllocPeriod is a period in which subframes indicated by the commonSF-Alloc repeat. The Pmch-InfoList IE may include all PMCH configuration information of one MBSFN region.

TABLE 3

In step 430, the UE 400 may acquire the location of the MBSFN subframe in which the desired MTCH is transmitted in MCH scheduling information MAC CE, which is one of MAC CE (Control Elements) of the received MAC PDU. have. In step 435, the terminal 400 may decode a desired MTCH (Multicast Traffic Channel) using MCH scheduling information.

Like the unicast service, the service area of the MBMS service should be designed so that there are no shadow areas or areas where reception signals are weak. To do this, you can perform a traditional drive test to optimize the cell and system settings based on the collected measurement information. However, it increases wireless network optimization costs and operating costs, and takes a lot of time. Therefore, researches for minimizing the drive test and improving the analysis process and the manual configuration of the wireless environment are being conducted under the name of the Minimization of Drive Test (MDT). This technique can be utilized to optimize the service area of MBMS service.

5 is a conceptual diagram illustrating the performance of MDT.

According to FIG. 5, a conventional drive test 500 loads measurement equipment on a vehicle, finds a range of sound regions, navigates a service area, and measures a signal state. In the MDT, the terminal 520 performs this instead. The NMS 505 may instruct to perform MDT. At this time, necessary configuration information is provided to the EM 510. The EM 510 configures the MDT configuration and delivers it to the eNB 515. The eNB 515 sends an MDT configuration to the UE 520 in step 525 and indicates the MDT. The UE 520 collects MDT measurement information. The MDT measurement information may include location and time information as well as signal measurement information. The collected information is reported to the eNB 515 in step 530. The eNB 515 forwards the collected information to the TCE 535. In one embodiment, the TCE 535 may be one server that collects MDT measurement information.

However, conventional MDT techniques focus on collecting measurement information that is less relevant to MBMS. In the present invention, the network selects a terminal to collect information necessary for optimizing the MBMS service area according to a predetermined rule. In addition, the network may be configured to record and report the information to the selected terminal using a predetermined method. In addition, the present invention proposes an efficient reporting method when considering that the UE continuously records the MBMS measurement information regardless of the standby mode or the connected mode.

6 is a view for explaining the difference between the MDT and the MDT for MBMS measurement information proposed in the present invention.

In the present invention, the MBMS measurement information measured based on the MDT measurement technology may include not only measurement information of a signal for MBMS service but also measurement location and measurement time information.

According to FIG. 6, MBMS measurement information may be collected based on the existing MDT technology. That is, the existing MDT technology can be largely divided into two categories. When the terminal in the standby mode is recording the measurement information, when switching to the connected mode, the "logged MDT in ILDE" reporting the recorded information to the base station and the terminal in the connected mode immediately reports the measurement information to the base station It is classified as “immediate MDT”. In Logged MDT, the terminal stops recording the measurement information when the connection mode is switched. Immediate MDT utilizes the existing RRC measurement operation as it is, and is characterized in that the terminal location information is additionally reported to the base station.

The present invention further considers “logged MDT in CONN”, which can record measurement information even in the terminal standby mode. Hereinafter, Logged MDT in CONN is compared with existing logged MDT in IDLE. Logged MDT in IDLE is set from the base station when the terminal is in the connected mode state 600. That is, the base station instructs the terminal in the connected mode to record the cell measurement information in the standby mode using the dedicated RRC message (605). The message includes configuration information for performing logged MDT. When the terminal is switched to the standby mode (610), the terminal collects and records cell measurement information by using the received configuration information. When the UE, which is performing the Logged MDT in IDLE, is switched to the connected mode again (615), the operation of recording the cell measurement information is stopped. In operation 620, the terminal transmits an indicator indicating to the base station that the terminal has information recorded by the terminal itself. This availability indicator is logMeasAvailable IE in the existing LTE standard technology. In the existing LTE standard technology, the availability indicator is to report to the base station when the terminal performs connection establishment, re-establishment, handover. The RRC messages used at this time are RRCConnectionSetupComplete, RRCConnectionReestablishmentComplete, and RRCConnectionReconfigurationComplete, respectively. When the base station receives the indicator from the terminal, the base station may request the recording information from the terminal by using a UE information procedure (625). Logged MDT in CONN can provide the necessary configuration information to the terminal in the connected state 630 through a dedicated RRC message as in the existing MDT (635). In the present invention, this is referred to as a dedicated control channel (DCCH) option. In addition, it is possible to instruct the logged MDT in CONN to the terminal through another method. In the LTE standard technology, the terminal may be provided with the MBMS service regardless of the connected mode or the standby mode. In the standby mode 640, the logged MDT cannot be set to the UE through the DCCH option. Accordingly, the present invention provides a method for providing configuration information for logged MDT on a broadcast control channel (BCCH) used to broadcast a multicast control channel (MCCH) or system information that is an MBMS control channel that can be received by the terminal in the standby mode. Suggest. (645). Since the MCCH or BCCH may be received even when the terminal is in the standby mode, the network may set the logged MDT at any time, regardless of the current mode of the terminal. The DCCH option may be used only for the terminal in the connected mode to set the logged MDT. In addition, since only a single terminal can be configured using a dedicated RRC message, it is inefficient even when the network configures logged MDTs to multiple terminals simultaneously. MDT is a function for optimizing the network of the operator, not to improve the user's convenience, so when setting the MDT to the terminal will be generally applied only when the user's consent is obtained in advance. Therefore, in the DCCH option, after confirming the user's agreement in advance, the network will generally set the MDT only for the terminal in which the agreement has been previously made. As described above, the MCCH / BCCH option may be used to set the MDT regardless of the UE's connection or standby mode. In addition, since a plurality of terminals can receive the MCCH and BCCH at the same time, it is efficient to configure a plurality of terminals at the same time. However, even then, the network does not need to instruct all terminals in a particular region to perform MDT. Therefore, there is a need for a method for selecting terminals to perform the MDT. In addition, if the terminal is in the standby mode, the base station can not determine exactly which terminal exists in its cell. As a result, when setting up logged MDTs, the network cannot verify user consent. Therefore, a method for compensating for this is required. One method is to determine whether to reject or perform an instruction to perform MDT from the network by checking the user's consent on the terminal itself. The present invention proposes a method in which a network selects terminals to perform a logged MDT and checks user consent by the terminal itself.

Although the UE performing the Logged MDT in CONN is switched from the standby mode 640 to the connected mode 650, the terminal continues to collect and record measurement information. According to the existing MDT technology, the terminal which has switched to the connected mode transmits the availability indicator to the base station indicating that there is recorded information (655). When the terminal transmits the availability indicator to the base station, the base station that has received the request may request the terminal to report it (660). The terminal may delete the reported information from the memory. However, since the measurement information is continuously recorded even in the connected mode, the terminal will retain the newly recorded information. If the terminal performs the handover (665), the availability indicator again reports to the base station (670). The base station will then request the recorded information again (675). If the terminal of the connected mode is talking to several cells while moving, the above-mentioned process will continue to occur. That is, as the availability indicator transmission of the terminal and data retrieval of the base station occur repeatedly, signaling overhead may increase. Therefore, on the other hand, since the MDT measurement information is not urgently needed, a method for reducing such signaling overhead is required.

The present invention proposes a method in which a network selects terminals to perform a logged MDT and checks user consent by the terminal itself.

FIG. 7 is a diagram for describing a method of selecting a terminal for performing MDT by a network when applying the MCCH / BCCH option. The base station 700 broadcasts the access class (AC) of the terminal to perform the MDT in the MCCH or BCCH. Each terminal has one AC value and randomly has a value between 0 and 9. For example, if the network wants to instruct about 20% of the terminals in the cell to perform MDT, the base station selects any value between 0 and 9, in this example 4 and 8, and broadcasts it on MCCH or BCCH. Cast (705). At this time, the terminal having the AC 4 (710) and 8 (715) is to perform the MDT.

Another method is that the network broadcasts a value between 0 and 1 (which is called factor_x in the present invention) (705), and when the terminals receive the value, randomly selects a value between 0 and 1. To derive. If the derived value is less than (or less than or equal to) the factor_x, the terminal is considered to perform MDT. Alternatively, if greater than (or greater than or equal to) factor_x, it may be defined as performing MDT. For example, if 20% of terminals in a cell want to instruct to perform MDT, the base station sets the value of factor_x to 0.2 and broadcasts it. The terminals in the cell that receive this select a random value between 0 and 1, and determine whether it is less than the factor_x. If less, the terminals 720 and 725 should perform MDT.

As mentioned above, the present invention proposes a method for confirming user consent by the terminal itself. To this end, user consent information of the terminal itself is required. In general, user information is stored in the HSS on the network. In the case of the existing MDT, the HSS transfers the user consent information to the MME or the base station. The MME or the base station determines which of the terminals in the connected mode state to indicate the MDT, based on the user agreement information.

However, in the present invention, since the UE in the standby state can be instructed to perform the MDT, when instructing the MDT to the UE in the standby state, the network cannot determine which standby state exists in the cell. Therefore, the terminal should confirm the user's consent by itself. To this end, the present invention is characterized in that when the terminal performs the ATTACH or TAU (Tracking Area Update) process, the user agreement information is provided to the terminal in the network. When the terminal powers on, the ATTACH process of registering the terminal itself to the network is performed. This is called the initial ATTACH process. The terminal sends an ATTACH REQUEST message to the MME to undergo an authentication process. If the authentication succeeds, the MME transmits an ATTACH ACCEPT message to the terminal.

The present invention is characterized in that the network includes user agreement information in the ATTACH ACCEPT message transmitted by the MME to the terminal. The user consent information includes at least whether to allow the terminal to perform MDT. For example, this can be indicated by using a 1-bit indicator. In addition to the ATTACH process, when the UE moves to change the tracking area to which it belongs, it notifies the MME. This process is called tracking area update (TAU). Even during the TAU process, the MME may deliver user consent information to the terminal.

8 is a diagram illustrating a process of confirming user consent by a terminal in the present invention. The terminal 800 must perform the ATTACH process at least once after power-on. Accordingly, the terminal transmits an ATTACH REQUEST 815 message to the MME 810. In order to perform the information to the MME, the terminal must switch to the connected mode. The message is delivered to the MME via the base station 805. If the authentication is successfully completed, the MME transmits an ATTACH ACCEPT 820 message to the terminal. The user consent information is included in the ATTACH ACCEPT message. This includes whether to allow the terminal to perform MDT. In step 825, the UE determines whether it can perform MDT based on the user consent information. The MME or the base station may instruct the execution of the MDT to a plurality of terminals in the cell using the MCCH or BCCH option. To this end, as described above, the factor_x value is determined (830, 835). The network entity that determines the terminal to perform the MDT will determine the factor_x value. The factor_x is broadcast through the base station (840, 845). In MCCH option, factor_x will be included in MCCH configuration information, and in BCCH option, it will be included in system information. System information is broadcast through various SIBs, depending on the type. Factor_x may be included in an existing SIB or a new SIB. In step 850, the UE will receive the broadcast factor_x. If the terminal itself is not allowed to perform the MDT, the information will be ignored. However, if the terminal is allowed to perform the MDT, the terminal selects any one value between 0 and 1. If the value selected in step 855 is less than factor_x, MDT is performed.

In the existing LTE standard technology, when the terminal performs connection establishment, re-establishment, and handover, it uses the availability indicator to inform the base station that it stores MDT measurement information. The terminal will delete the information once reported to the base station. Therefore, if the UE reports that it has MDT measurement information stored in the base station during the connection establishment process, and the base station retrievals it, it does not have the stored information anymore. Will not send. However, if the terminal is performing logged MDT in CONN, even if reporting information recorded in the base station, the newly recorded information will occur. The UE transmits the availability indicator to the base station very frequently in the connected mode, and accordingly, retrieval may occur frequently. In general, when the base station is not in a network congestion situation, when the availability indicator is received, the base station will retrieval the MDT measurement information stored by the terminal using the UE information procedure. Since the MDT measurement information is used by the operator for network optimization after the collection is completed, it is not urgent information. Therefore, frequent retrieval of MDT information only increases signaling overhead and is not beneficial.

Therefore, the present invention proposes a method for suppressing frequent retrieval of MDT measurement information stored in a terminal.

In the first method, the terminal transmits a 1-bit indicator indicating whether the logged MDT in CONN is being performed to the base station together with the availability indicator. The new indicator will be included in the RRC message including the availability indicator. The base station receiving the new 1-bit indicator may determine whether to perform retrieval now or perform retrieval later after logging MDT in CONN is completed.

As another method, when the base station transmits the MDT configuration information, the terminal transmits a condition to the terminal in advance to send the availability indicator. In the existing LTE standard technology, when the terminal stores the MDT measurement information when performing connection establishment, re-establishment, and handover, the RRCConnectionSetupComplete, RRCConnectionReestablishmentComplete, and RRCConnectionReconfigurationComplete message include an availability indicator indicating this. However, in the second method of the present invention, even if the terminal stores MDT measurement information at the event, if the terminal does not satisfy a predetermined condition set by the base station, the terminal does not send the availability indicator to the base station. For example, the second method is to send an availability indicator only when the amount of MDT measurement information stored in the terminal exceeds a specific threshold. The third method is that once the terminal transmits the availability indicator to the base station, the terminal prohibits transmitting the availability indicator again for a predetermined time.

The last method is to not send an availability indicator to the base station until the terminal terminates logged MDT in CONN. If the terminal does not terminate the logged MDT in CONN and is running, the terminal does not include the availability indicator in the RRCConnectionSetupComplete, RRCConnectionReestablishmentComplete, and RRCConnectionReconfigurationComplete messages when performing connection establishment, re-establishment, and handover. When Logged MDT in CONN is terminated, the availability indicator is included in the RRCConnectionSetupComplete, RRCConnectionReestablishmentComplete, and RRCConnectionReconfigurationComplete messages when performing connection establishment, re-establishment, and handover.

FIG. 9 is a diagram for describing a method of transmitting a 1-bit indicator indicating whether a logged MDT in CONN is currently performed to a base station in order to prevent frequent retrieval of MDT measurement information. In step 910, the terminal 900 notifies the base station 905 by using the UECapabilityInformation message that it can perform logged MDT in CONN. To this end, the UECapabilityInformtion message has a 1-bit indicator, the format is ENUMERATED {supported}. In the present invention, the indicator is called loggedMeasCONN. Since the UE in standby mode may be instructed to perform Logged MDT in CONN using MCCH or BCCH, the BS may not have a chance to receive a UECapabilityInformation message. Therefore, step 910 is an option, and even if the actual base station does not obtain the indicator, the terminal may indicate logged MDT in CONN. In step 915, the base station will instruct a specific terminal to perform logged MDT in CONN using one of the DCCH / MCCH / BCCH options. If the RRC message for transmitting the existing MDT configuration information, that is, the loggedMeasurementConfiguration message, is reused, a 1-bit indicator indicating execution of Logged MDT in CONN may be included in the MDT configuration information. For example, if the 1-bit indicator is not included, only the existing logged MDT in IDLE is performed. Otherwise, the logged MDT in CONN is performed. The 1 bit indicator shall have the form of ENUMERATED {setup}. In the present invention, the 1-bit indicator is called loggedMeasForCONN. The 1-bit indicator may also be not necessarily required as an option. That is, when receiving the MDT configuration information, if the MBSFN area configuration information is included, it may be regarded as necessarily performing logged MDT in CONN. Or, instead of reusing an existing loggedMeasurementConfiguration message, you can define a new dedicated RRC message that sets logged MDT in CONN. The MDT configuration information includes not only the 1-bit indicator but also information such as time interval information (T33x) for performing logged MDT in CONN, a recording period for periodic recording, and an absolute time for receiving configuration information. In step 920, if the terminal receives MDT configuration information from the base station and successfully decodes it, it may immediately perform logged MDT in CONN. In Logged MDT in CONN, the UE will collect and store MDT measurement information in connected mode as well as in standby mode. Therefore, as in logged MDT in IDLE, which collects and stores MDT measurement information only in the standby mode, it is not necessary to perform the MDT after the terminal is switched to the standby mode. You can perform MDT right away even if you are connected. In order to match the existing method, if the terminal is switched to the standby mode or already in the standby mode when receiving the MDT configuration information, it may start logged MDT in CONN (930). When the terminal starts logged MDT in CONN, it immediately starts the T33x timer (T33x). The terminal will perform logged MDT in CONN until the timer expires. In step 935, the terminal is switched to the connected mode. In step 940, as in the existing LTE standard technology, if all of the following conditions are satisfied, an availability indicator may be sent to the base station.

Condition 1: The UE stores MDT measurement information which has not been reported.

Condition 2: The terminal is performing one of a connection establishment, a re-establishment, and a handover process.

Condition 3: The UE sends an RRCConnectionSetupComplete, RRCConnectionReestablishmentComplete, or RRCConnectionReconfigurationComplete message.

In the present invention, a 1-bit indicator, loggedMeasCONNcont, may be included with the availability indicator. The 1-bit indicator has a format of ENUMERATED {true} and is included in the RRCConnectionSetupComplete, RRCConnectionReestablishmentComplete, or RRCConnectionReconfigurationComplete message when the terminal is executing logged MDT in CONN at the time of sending the availability indicator. The base station can determine whether the terminal transmitting the availability indicator is still performing logged MDT in CONN and collecting MDT measurement information through the 1-bit indicator. Based on the determination criteria, the base station is still performing the logged MDT in CONN, but may determine whether to retrieval the MDT measurement information from the terminal or whether to retrieval after completing the logged MDT in CONN to reduce the signaling overhead. . If the retrieval is determined, in step 945, to request a retrieval to the UE, a UEInformationRequest message is transmitted. In step 950, the UE transmits the information stored in the UEInformationResponse message to the base station. At this time, if the UE continues to perform logged MDT in CONN to collect MDT measurement information, it should be defined to what extent the MDT measurement information stored to the UEInformationResponse message is included. In the first method, the collected MDT measurement information may be included in the UEInformationResponse message until the UE successfully receives and decodes the indicator requesting the report of the MDT measurement information in the UEInformationRequest message. In the second method, after successfully receiving and decoding an indicator requesting reporting of the MDT measurement information, the collected MDT measurement information may be included in the UEInformationResponse message until the actual UEInformationResponse message is configured. Another method may include in the UEInformationResponse message the MDT measurement information collected until the terminal transmits the loggedMeasCONNCont indicator to the base station. In step 955, the terminal deletes the MDT measurement information to be reported to the base station from the memory. When the T33x timer expires in step 955, the terminal stops the logged MDT in CONN that is being performed (960). Thereafter, when the UE performs connection establishment, re-establishment, and handover, the UE includes an availability indicator indicating this in the RRCConnectionSetupComplete, RRCConnectionReestablishmentComplete, and RRCConnectionReconfigurationComplete messages, and transmits them to the base station.

FIG. 10 is a diagram for describing a method of sending an availability indicator only when a data amount of MDT measurement information stored in a terminal exceeds a specific threshold.

According to FIG. 10, the present invention is characterized in that the terminal sends the availability indicator to the base station only when the amount of data of the MDT measurement information stored is greater than a specific threshold value. Step 1010 is the same as step 910. In step 1015, the base station 1005 provides the terminal 1000 with MDT configuration information by using one of the DCCH / MCCH / BCCH options. The MDT configuration information includes a specific threshold value for the amount of data of the MDT measurement information, which is a condition value for the terminal to transmit the availability indicator. In the present invention, the threshold is called LogsAvailable. Steps 1020, 1025, 1030, and 1035 correspond to steps 920, 925, 930, and 935. In step 1040, the terminal determines whether the availability indicator can be sent.

Condition 1: The UE stores MDT measurement information which has not been reported.

Condition 2: The terminal is performing one of a connection establishment, a re-establishment, and a handover process.

Condition 3: The UE sends an RRCConnectionSetupComplete, RRCConnectionReestablishmentComplete, or RRCConnectionReconfigurationComplete message.

Condition 4: The terminal stores and the amount of data of MDT measurement information is greater than (or more than or equal to) the threshold LogsAvailable.

If all of the above conditions are met, the terminal may transmit an availability indicator to the base station. If Logged in CONN is terminated, the condition 4 is not considered and if conditions 1 to 3 are satisfied, an availability indicator is transmitted. In another embodiment, the availability indicator may be transmitted when the conditions 1 to 3 are satisfied for the first time. In another embodiment, when the terminal transmits an availability indicator, the terminal may also report the data amount of the stored MDT measurement information to the base station. Steps 1045, 1050, 1055, 1060, 1065, and 1070 are the same as steps 945, 950, 955, 965, and 970.

Instead of the data amount of MDT measurement information introduced in this embodiment, the number of recordings may be applied.

That is, the base station may provide a recording count value as a condition value for transmitting the availability indicator to the terminal.

The terminal records MBMS measurement information at regular intervals or when an event occurs. At this time, the terminal assumes that the number of recordings has increased by one.

If the number of recordings counted by the terminal is not greater than or equal to the value of the number of recordings provided to the base station, even if the conditions 1, 2, and 3 are satisfied, the terminal does not transmit an availability indicator.

FIG. 11 is a diagram for describing a method in which the terminal does not transmit the availability indicator again for a predetermined time when the terminal transmits the availability indicator to the base station once.

According to FIG. 11, operation 1110 is the same as operation 910. In step 1115, the base station 1105 provides the terminal 1100 with MDT configuration information by using one of the DCCH / MCCH / BCCH options. The MDT configuration information includes a time value for which the terminal cannot send the availability indicator again for a predetermined time after sending the availability indicator. In the present invention, this is called prohibit time duration. Steps 1120, 1125, 1130, and 1135 correspond to steps 920, 925, 930, and 935. In step 1140, the UE transmits an Availability indicator to the base station. At this time, in step 1145, the terminal sends an availability indicator and starts one timer having a period of the prohibit time duration. The terminal cannot transmit an availability indicator until the timer expires. That is, the terminal may transmit the availability indicator to the base station only when all of the following conditions are satisfied.

Condition 1: The UE stores MDT measurement information which has not been reported.

Condition 2: The terminal is performing one of a connection establishment, a re-establishment, and a handover process.

Condition 3: The UE sends an RRCConnectionSetupComplete, RRCConnectionReestablishmentComplete, or RRCConnectionReconfigurationComplete message.

Condition 4: The terminal is not operating the prohibit timer.

In step 1150, the UE performs a handover, but does not satisfy all of the above conditions (since the timer is still running), and thus does not transmit an availability indicator to the base station. In step 1155, the UE performs handover again. In this case, since all of the above conditions are satisfied (the timer expires), the terminal may transmit an availability indicator. In another embodiment, if Logged in CONN is terminated, the condition 4 is not considered and if conditions 1 to 3 are satisfied, an availability indicator is transmitted. In another embodiment, the timer may be reset and restarted when a handover occurs. Steps 1165, 1170, and 1175 correspond to steps 960, 965, and 970.

12 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention.

According to FIG. 12, the base station of the present invention includes a transceiver 1205, a controller 1210, a multiplexing and demultiplexing unit 1220, a control message processing unit 1235, various upper layer processing units 1225 and 1430, and a scheduler ( 1215).

The transceiver 1205 transmits data and a predetermined control signal through a forward carrier and receives data and a predetermined control signal through a reverse carrier. When a plurality of carriers are set, the transceiver 1205 performs data transmission and control signal transmission and reception to the plurality of carriers.

The multiplexing and demultiplexing unit 1220 multiplexes the data generated by the upper layer processing units 1225 and 1230 or the control message processing unit 1235 or demultiplexes the data received by the transmitting and receiving unit 1205 so that the appropriate upper layer processing unit 1225, 1230, the control message processor 1235, or the controller 1210. The control message processor 1235 processes the control message transmitted by the terminal to take a necessary action, or generates a control message to be transmitted to the terminal and delivers the control message to the lower layer.

The upper layer processing units 1225 and 1230 may be configured for each terminal service, and may process data generated from user services such as FTP or VoIP, and deliver the data to the multiplexing and demultiplexing unit 1220 or the multiplexing and demultiplexing unit 1220. Process the data delivered from) and deliver it to the service application of the upper layer.

The controller 1210 determines when the terminal transmits the MBMS and controls the transceiver.

The scheduler 1215 allocates a transmission resource to a terminal at an appropriate time in consideration of a buffer state, a channel state, and an active time of the terminal, and processes a signal transmitted by the terminal to a transceiver or signals a terminal. Process to send.

13 is a block diagram showing the internal structure of a terminal according to an embodiment of the present invention.

According to FIG. 13, the terminal transmits / receives data with the upper layer 1310 and transmits / receives control messages through the control message processor 1315. When the control signal or data is transmitted to the base station, the terminal transmits data through the transmitter 1300 after multiplexing through the multiplexing device 1305 under the control of the controller 1320. On the other hand, upon reception, the terminal receives the physical signal to the receiver 1300 under the control of the control unit 1320, and then demultiplexes the received signal by the demultiplexing apparatus 1305, and the upper layer 1310 according to the message information, respectively. Or the control message processing unit 1315.

Meanwhile, in the above description, the terminal is composed of a plurality of blocks, and each block performs a different function. However, this is only an example and is not necessarily limited thereto. For example, the controller 1320 itself may perform a function performed by the demultiplexer 1305.

In this case, the controller 1320 may detect the occurrence of downlink scheduling in an arbitrary transmission time interval. The controller 1320 determines whether the downlink scheduling is performed according to whether the terminal is set to transmission mode 9 or whether the transmission time interval corresponds to a multimedia broadcast multicast service single frequency network (MBSFN) subframe. The controller 1320 controls to process or ignore the downlink scheduling according to the determination result.

More specifically, the controller 1320 determines whether the transmission time interval corresponds to the measurement interval, and when the measurement period corresponds to the measurement interval, controls to ignore the downlink scheduling.

In addition, the controller 1320 determines whether the terminal is set to a transmission mode 9 when the transmission time interval does not correspond to a measurement interval, and determines whether the transmission time interval is an MBSFN subframe when the transmission time interval is not set to the transmission mode 9. In case of the MBSFN subframe, the downlink scheduling is ignored.

In addition, the controller 1320 controls to process the downlink scheduling when the transmission time interval is not the MBSFN subframe.

When the transmission mode 9 is set to the transmission mode 9, the controller 1320 controls to process the downlink scheduling.

On the other hand, the present specification and the drawings have been described with respect to the preferred embodiments of the present invention, although specific terms are used, it is merely used in a general sense to easily explain the technical details of the present invention and help the understanding of the invention, It is not intended to limit the scope of the invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

Claims (26)

In the method of measuring the Minimization of Drive Test (MDT) of the base station in a mobile communication system, Transmitting an MDT measurement configuration message to at least one terminal; And Receiving an MDT measurement result from the at least one terminal, The MDT measurement setting message, The measurement method, characterized in that transmitted through a control channel that can be received by the at least one terminal. The method of claim 1, wherein the control channel, A measurement method, characterized in that it is any one of a broadcast control channel (BCCH) used to broadcast a multicast control channel (MCCH) or system information (System Information) that is a control channel of a multimedia broadcast multicast service (MBMS). The method of claim 1, wherein the MDT measurement setting message, And measuring an access class (AC) for at least one terminal to perform the MDT measurement. The method of claim 1, wherein the MDT measurement setting message, Contains a parameter with a value between 0 and 1, The parameter is a measurement method, characterized in that used to select the terminal to perform the MDT measurement. The method of claim 1, wherein receiving the MDT measurement result from the at least one terminal comprises: Receiving an availability indicator message from the at least one terminal and information indicating whether the at least one terminal has finished MDT; Determining whether the at least one terminal has terminated MDT based on information indicating whether the at least one terminal has terminated MDT; And If the MDT measurement is completed as a result of the determination, transmitting a message requesting to transmit the MDT measurement result. The method of claim 1, wherein receiving the MDT measurement result from the at least one terminal comprises: Receiving an availability indicator message and information indicating a data amount of MDT measurement information stored in the at least one terminal, from the at least one terminal; Determining whether the data amount of the stored MDT measurement information exceeds a threshold value; And And transmitting a message requesting to transmit the MDT measurement result when the data amount of the stored MDT measurement information exceeds a threshold as a result of the determination. In the base station for performing the MDT (Minimization of Drive Test) measurement in a mobile communication system, A transceiver for performing data communication; And a controller for transmitting an MDT measurement configuration message to at least one terminal and receiving an MDT measurement result from the at least one terminal. The MDT measurement setting message, The base station, characterized in that transmitted through a control channel that can be received by the at least one terminal. The method of claim 7, wherein the control channel, A base station, characterized in that any one of a multicast control channel (MCCH), which is a control channel of a multimedia broadcast multicast service (MBMS), or a broadcast control channel (BCCH) used to broadcast system information. The method of claim 7, wherein the MDT measurement setting message, A base station comprising an access class (AC) for at least one terminal to perform the MDT measurement. The method of claim 7, wherein the MDT measurement setting message, Contains a parameter with a value between 0 and 1, The parameter is a base station, characterized in that used to select a terminal to perform the MDT measurement. The method of claim 7, wherein the control unit, Receiving an availability indicator message from the at least one terminal and information indicating whether the at least one terminal has terminated MDT, and based on the information indicating whether the at least one terminal has terminated MDT, the at least one terminal And determining whether the MDT has ended, and if the MDT measurement is finished, transmitting a message requesting the transmission of the MDT measurement result. The method of claim 7, wherein the control unit, Receiving an availability indicator message and information indicating a data amount of MDT measurement information stored in the at least one terminal from the at least one terminal, and determining whether the data amount of the stored MDT measurement information exceeds a threshold value; And transmitting a message requesting to transmit the MDT measurement result when the data amount of the stored MDT measurement information exceeds a threshold. In the method of measuring the Minimization of Drive Test (MDT) of the terminal in a mobile communication system, Receiving an MDT measurement setup message instructing to perform MDT measurement from a base station; Measuring signal information related to a multimedia broadcast multicast service (MBMS) received by the terminal according to the MDT measurement configuration message; And And transmitting the MDT measurement result including the measured MBMS-related signal information to the base station. The method according to claim 13, wherein the MDT measurement setting message, Measurement method characterized in that it is received from any one of the multicast control channel (MCCH) or the broadcast control channel (BCCH) used for broadcasting (System Information), which is a control channel of the multimedia broadcast multicast service (MBMS) . The method of claim 13, wherein the measuring of the MBMS signal related information received by the terminal according to the MDT measurement setting message comprises: And measuring information related to a multimedia broadcast multicast service (MBMS) signal received by the terminal when the access class of the terminal corresponds to AC included in the MDT measurement configuration message. The method of claim 13, wherein the measuring of the MBMS signal related information received by the terminal according to the MDT measurement setting message comprises: It measures the information related to the Multimedia Broadcast Multicast Service (MBMS) signal received by the terminal according to a result of comparing the random value between 0 and 1 selected by the terminal with a parameter between 0 and 1 included in the MDT measurement setting message. The measuring method characterized by the above-mentioned. The method of claim 13, wherein the measuring of the MBMS signal related information received by the terminal according to the MDT measurement setting message comprises: Determining whether user consent information for performing the MDT measurement exists in the terminal; And if the user consent information exists, measuring the MBMS signal related information received by the terminal. The method of claim 13, wherein the reporting step of transmitting the measured information related to the MBMS signal to the base station, Transmitting an availability indicator message and information indicating whether the terminal has terminated the MDT; And Receiving a message requesting to transmit the MDT measurement result from the base station. The method of claim 13, wherein the reporting step of transmitting the MBMS signal related information to the base station, Transmitting an availability indicator message and information indicating the amount of data of the MDT measurement result stored in the terminal to the base station; And Receiving a message requesting to transmit the MDT measurement result from the base station. In the terminal for performing the MDT (Minimization of Drive Test) measurement in a mobile communication system, A transceiver for performing data communication; Receiving an MDT measurement configuration message instructing to perform the MDT measurement from the base station, and measures the information related to the Multimedia Broadcast Multicast Service (MBMS) signal received by the terminal according to the MDT measurement configuration message, the measured MBMS signal related And a controller for transmitting the MDT measurement result including the information to the base station. The method of claim 20, wherein the MDT measurement setting message, A terminal characterized in that it is received from any one of a broadcast control channel (BCCH) used to broadcast a multicast control channel (MCCH) or system information (System Information) that is a control channel of a multimedia broadcast multicast service (MBMS). The method of claim 20, wherein the control unit, And measuring information related to a multimedia broadcast multicast service (MBMS) signal received by the terminal when the access class of the terminal corresponds to AC included in the MDT measurement configuration message. The method of claim 20, wherein the control unit, It measures the information related to the Multimedia Broadcast Multicast Service (MBMS) signal received by the terminal according to a result of comparing the random value between 0 and 1 selected by the terminal with a parameter between 0 and 1 included in the MDT measurement setting message. Terminal, characterized in that. The method of claim 20, wherein the control unit, And determining whether the user consent information for performing the MDT measurement exists in the terminal, and if the user consent information exists, measuring the MBMS signal related information received by the terminal. The method of claim 20, wherein the control unit, And an availability indicator message and information indicating whether the terminal has terminated the MDT to the base station, and receiving a message requesting to transmit the MDT measurement result from the base station. The method of claim 20, wherein the control unit, And an information indicating the availability indicator message and the data amount of the MDT measurement result stored in the terminal to the base station, and receiving a message requesting to transmit the MDT measurement result from the base station.

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