KR20120048858A - Apparatus and method for performing mdt(minimization driving test) in wireless communication system - Google Patents

Abstract

PURPOSE: An operation test minimizing method and an apparatus thereof in a wireless communication system are provided to efficiently control an MDT procedure in handover. CONSTITUTION: An SeNB(Source evolved-NodeB) transmits an MDT request message to a TeNB(Target evolved-NodeB) related to MDT(Minimization Driving Test) control(S1520). The TeNB inspects a state of the MDT which is performed in the SeNB(S1530). The TeNB transmits an MDT available indication message and an MDT reconfiguration message(S1540). The SeNB determines whether the MDT is performed in a target cell(S1550).

Description

Apparatus and Method For Performing Minimization Driving Test (MDT) in Wireless Communication System}

The present invention relates to a wireless communication technology, and more particularly, to an apparatus and method for configuring and performing a driving environment (Minimization Driving Test (MDT)).

In order to increase the performance of a wireless communication system, a wireless communication network should always consider throughput, frequency efficiency, mobility, coverage, and enhancement of multimedia broadcast / multimedia service (MBMS). As wireless communication technologies have evolved, each of these factors affecting wireless communication networks has changed significantly.

For example, wireless communication systems generally use one bandwidth for data transmission, but vary in bandwidth for each mobile generation. For example, the second generation wireless communication system uses a bandwidth of 200KHz ~ 1.25MHz, the third generation wireless communication system uses a bandwidth of 5MHz ~ 10MHz. To support the increasing transmission capacity, the recent Long Term Evolution (LTE) or IEEE 802.16m of the 3rd Generation Partnership Project (3GPP) continues to expand its bandwidth to 20 MHz or more.

As such, it is essential to increase the bandwidth in order to increase transmission capacity. However, except for some regions of the world, the allocation of a large bandwidth frequency is not easy due to the lack of frequency resources.

In order to operate an effective mobile communication system, a service provider must consider various conditions according to the environment. That is, the service provider should consider how to use the scarce frequency resources, for example, how much cell radius to have when establishing a base station, how much the frequency requirements of the cell, and the like.

In order to effectively operate the system while maintaining a high quality of service (QoS), the service provider needs to know what the coverage area of the network is, for example, the call quality state in the cell or the state of signal transmission and reception.

An object of the present invention is to provide an apparatus and method for performing a driving test minimization in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for effectively controlling a Minimization Driving Test (MDT) procedure even when a handover is performed.

Another object of the present invention is to provide an apparatus and method for preventing power consumption and memory waste of a terminal by controlling the execution of MDT during handover.

Another object of the present invention is to provide an apparatus and method for controlling MDT performance during handover using a handover procedure.

It is another object of the present invention to provide an apparatus and method for indicating MDT setting in a wireless communication system.

It is also an object of the present invention to provide an apparatus and method for instructing MDT reset in a wireless communication system.

In addition, an object of the present invention is to provide an apparatus and method for transmitting and receiving information regarding the availability and reset of MDT in a wireless communication system.

An aspect of the present invention is a method for processing a Minimization Driving Test (MDT) of a source base station at the time of handover in a wireless communication system, when it is determined that handover is necessary based on a measurement report received from a terminal performing MDT. Transmitting the first MDT message about the MDT to the target base station, based on the second MDT message transmitted by the target base station in response to the first message, determining whether the MDT is to be continued at the target base station, and based on the determination And transmitting a third MDT message to the terminal.

In this case, the first MDT message may include at least one of the MDT information of the source base station and an indicator indicating whether the MDT can be performed.

Here, the MDT information of the source base station, the MDT version / release information of the source base station, the information on the time of the source base station, the information about the period of the log proceeding, the information about the log period / interval, the region to perform the MDT measurement It may include at least one of information on, information on a Public Land Mobile Network (PLMN) ID capable of MDT, information on the list of MDT triggering events, information on the MDT triggering event type.

In the MDT processing method of the source base station, the second MDT message may include at least one of the MDT information of the target base station and an indicator indicating whether the MDT can be performed.

In this case, the MDT information of the target base station may include at least one of MDT version / release information of the target base station and MDT resetting information according to the MDT setting of the target base station. In this case, the MDT reset information may include information on the time of the target base station, information on the period during which the log proceeds, information on the log period / interval, information on the region where the MDT measurement is performed, information on the cell ID of the target cell, The information may include at least one of information on a tracking ID of a target cell, information on a Public Land Mobile Network (PLMN) ID of a target cell, information on a list of MDT triggering events, and information on an MDT triggering event type.

In the MDT processing method of the source base station, the third MDT message may include at least one of information indicating whether to perform the MDT in the target base station and MDT resetting information according to the MDT setting of the target base station.

In this case, the MDT resetting information may include information about the time of the target base station, information about the period during which the log proceeds, information about the log period / interval, information about the region where the MDT measurement is performed, information about the cell ID of the target cell. It may include at least one of information on a tracking ID of a target cell, information on a Public Land Mobile Network (PLMN) ID of a target cell, information on a list of MDT triggering events, and information on an MDT triggering event type.

In the MDT processing method of the source base station, the third MDT message may be the same as the second MDT message.

In the MDT processing method of the source base station, when the second MDT message is not received from the target base station, it is determined that the MDT is not performed in the target cell, and based on this, the third MDT message may be transmitted to the terminal.

In the MDT processing method of the source base station, at least one of the first MDT message transmission step, whether to perform the MDT execution step, and the third MDT message transmission step may be performed together with the handover procedure.

Another aspect of the present invention is a method for processing a Minimization Driving Test (MDT) of a target base station during a handover in a wireless communication system, the method comprising at least one of MDT configuration information of the source base station received from the source base station and an MDT continuation request; 1 reviewing the MDT status based on the MDT message and transmitting the second MDT message including at least one of MDT progress information and MDT reset information based on the MDT status review.

If the target base station cannot process the first MDT message received from the source base station, the second MDT message may not be transmitted.

In the MDT processing method of the target base station, at least one of the MDT status review step and the second MDT message transmission step may be performed together with the handover procedure.

Another aspect of the present invention is a method for processing a Minimization Driving Test (MDT) of a terminal during handover in a wireless communication system, the method comprising: transmitting a predetermined measurement report to a source base station and MDT in a target cell received from the source base station; And changing the MDT setting based on an MDT message including at least one of an indication of whether to continue or the MDT reset information.

In this case, the MDT setting change may be to change the MDT setting to any one of maintaining the MDT setting, stopping the MDT, and resetting the MDT.

According to the present invention, even when a handover is performed, the Minimization Driving Test (MDT) procedure can be effectively controlled. According to the present invention, it is possible to appropriately control the execution of the MDT during the handover, thereby preventing power consumption and memory waste of the terminal. According to the present invention, it is possible to effectively control the execution of MDT during handover using the handover procedure.

1 is a block diagram illustrating a wireless communication system to which the present invention is applied.
2 is a block diagram showing functional division between an E-UTRAN and an EPC in a system to which the present invention is applied.
3 is a block diagram illustrating a radio protocol structure for a user plane in a system to which the present invention is applied.
4 is a block diagram illustrating a radio protocol structure for a control plane in a system to which the present invention is applied.
5 is a conceptual diagram schematically illustrating a handover of a terminal between base stations in a system to which the present invention is applied.
FIG. 6 is a flowchart schematically illustrating a handover process of changing a base station when a terminal is connected to an LTE system using a single component carrier in a system to which the present invention is applied.
FIG. 7 is a conceptual diagram schematically illustrating a concept of a driving test for measuring wireless call quality and / or coverage using a vehicle in a system to which the present invention is applied.
FIG. 8 is a conceptual diagram schematically illustrating measuring a communication environment of a network, that is, wireless call quality and / or coverage, using MDT in a system to which the present invention is applied.
9 is a flowchart schematically illustrating a method for setting an MDT in a system to which the present invention is applied.
10 is a conceptual diagram schematically illustrating an example of forming a log in periodic MDT in a system to which the present invention is applied.
11 is a flowchart schematically illustrating a method of setting an event trigger MDT in a system to which the present invention is applied.
FIG. 12 is a conceptual diagram schematically illustrating an example of creating a log in a mixture of a periodic method and an event trigger method in a system to which the present invention is applied.
13 is a flowchart schematically illustrating the operation of a network for MDT measurement in a system to which the present invention is applied.
14 is a flowchart schematically illustrating an operation of a terminal for MDT measurement in a system to which the present invention is applied.
FIG. 15 is a flowchart schematically illustrating that an MDT control procedure is performed along with a handover preparation procedure performed between a source base station and a target base station in a system to which the present invention is applied.
FIG. 16 is a flowchart schematically illustrating that an MDT control procedure is performed along with a handover procedure performed between a terminal and a source base station in a system to which the present invention is applied.
FIG. 17 is a flowchart schematically illustrating MDT control performed by a source base station when performing a handover procedure in a system to which the present invention is applied.
18 is a flowchart schematically illustrating MDT control performed by a target base station when performing a handover procedure in a system to which the present invention is applied.
19 is a flowchart schematically illustrating an MDT control performed by a terminal when performing a handover procedure in a system to which the present invention is applied.
20 is a block diagram illustrating a wireless communication system in which an embodiment of the present invention is implemented.

Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings and examples in connection with the present disclosure. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible, even if displayed on different drawings. In addition, in describing the embodiments of the present specification, when it is determined that the detailed description of the related well-known configuration or function may obscure the subject matter of the present specification, the detailed description thereof will be omitted.

In addition, in describing the components of the present specification, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled", or "connected" to another component, that component may be directly connected or connected to that other component, but there is another component between each component. It will be understood that may be "connected", "coupled", "connected".

In addition, the present invention will be described with respect to a wireless communication network. The work performed in the wireless communication network may be performed in a process of controlling a network and transmitting data by a system (e.g., a base station) Work can be done at a terminal connected to the network.

1 is a block diagram illustrating a wireless communication system. This may be a network structure of 3GPP LTE / LTE-A. The E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) includes a base station 20 (BS) that provides a control plane and a user plane to a user equipment (UE) 10. do.

The terminal 10 may be fixed or mobile and may be called by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), and a wireless device. .

The base station 20 refers to a fixed station communicating with the terminal 10, and may be referred to by other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and the like.

One or more cells may exist in one base station 20. In this case, the cell should be interpreted as a comprehensive meaning representing a part of the area covered by the base station 11 and encompasses various coverage areas such as a mega cell, a macro cell, a micro cell, a pico cell, a femto cell, and a relay.

An interface for transmitting user traffic or control traffic may be used between the base stations 20. The base stations 20 may be connected to each other through an X2 interface.

The base station 20 is connected to a Mobility Management Entity (MME) through an Evolved Packet Core (EPC), more specifically, S1-MME through an S1 interface, and a Serving GateWay (S-GW) through S1-U. The S1 interface supports a many-to-many-relation between the base station 20 and the MME / SAE gateway 30.

Hereinafter, downlink means communication from the base station 20 to the terminal 10, and uplink means communication from the terminal 10 to the base station 20. In downlink, the transmitter may be part of the base station 20 and the receiver may be part of the terminal 10. In addition, in uplink, the transmitter may be part of the terminal 10 and the receiver may be part of the base station 20.

2 is a block diagram illustrating a functional split between an E-UTRAN and an EPC in a system to which the present invention is applied. The hatched box represents the radio protocol layer and the white box represents the functional entity of the control plane. Describe the function of each functional entity.

The base station performs the following functions.

(1) Radio resource management such as radio bearer control, radio admission control, connection mobility control, and dynamic resource allocation to a terminal ; RRM) function. (2) Internet Protocol (IP) header compression and encryption of user data streams. (3) Routing of user plane data to S-GW. (4) Scheduling and sending of paging messages. (5) Scheduling and transmission of broadcast information. (6) Set up measurements and measurement reports for mobility and scheduling.

The MME performs the following functions.

(1) Non-Access Stratum (NAS) signaling. (2) NAS signaling security. (3) idle mode UE Reachability, (4) tracking area list management. (5) Roaming Functions (6) Authentication.

S-GW performs the following functions.

(1) mobility anchoring. (2) lawful interception.

P-GW (P-Gateway) performs the following functions.

(1) Terminal IP (Internet Protocol) allocation. (2) packet filtering.

3 is a block diagram illustrating a radio protocol architecture for a user plane in a system to which the present invention is applied. 4 is a block diagram illustrating a radio protocol structure for a control plane in a system to which the present invention is applied. The data plane is a protocol stack for user data transmission, and the control plane is a protocol stack for control signal transmission.

3 and 4, a physical layer (PHY) provides an information transfer service to a higher layer by using a physical channel. The physical layer is connected to a medium access control (MAC) layer, which is a higher layer, through a transport channel.

Data travels between the MAC and physical layers over the transport channel. Transport channels are classified according to how and with what characteristics data is transmitted over the air interface. Data moves between physical layers, that is, between physical layers of a transmitter and a receiver. In the physical layer, a physical control channel may be used.

Physical Downlink Control CHannel (PDCCH) informs the UE of resource allocation of Paging CHannel (PCH) and DownLink Shared CHannel (DL-SCH) and Hybrid Automatic Repeat reQuest (HARQ) information related to DL-SCH.

The PDCCH may carry an uplink scheduling grant informing the UE of resource allocation of uplink transmission.

The Physical Control Format Indicator CHannel (PCFICH) informs the UE of the number of OFDM symbols used for PDCCHs and is transmitted every subframe.

PHICH (Physical Hybrid ARQ Indicator CHannel) carries a HARQ ACK / NAK signal in response to uplink transmission.

Physical Uplink Control CHannel (PUCCH) carries uplink control information such as HARQ ACK / NAK, scheduling request, and CQI for downlink transmission.

PUSCH (Physical Uplink Shared CHannel) carries UL-SCH (UpLink Shared CHannel).

Functions of the MAC layer include mapping between logical channels and transport channels and multiplexing / demultiplexing into transport blocks provided as physical channels on transport channels of MAC service data units (SDUs) belonging to the logical channels.

The MAC layer provides a service to a Radio Link Control (RLC) layer through a logical channel. The logical channel may be divided into a control channel for transmitting control region information and a traffic channel for delivering user region information.

Functions of the RLC layer include concatenation, segmentation, and reassembly of RLC SDUs.

In order to guarantee the various quality of service (QoS) required by the radio bearer (RB), the RLC layer uses a transparent mode (TM), an unacknowledged mode (UM), and an acknowledged mode. , Three modes of operation (AM). AM RLC provides error correction through Automatic Repeat reQuest (ARQ).

Functions of the Packet Data Convergence Protocol (PDCP) layer in the user plane include delivery of user data, header compression, and ciphering. Functions of the PDCP layer in the user plane include the transfer of control plane data and encryption / integrity protection.

The RRC (Radio Resource Control) layer is defined only in the control plane. The RRC layer is responsible for the control of logical channels, transport channels and physical channels in connection with the configuration, re-configuration and release of radio bearers.

RB refers to a logical path provided by the first layer (PHY layer) and the second layer (MAC layer, RLC layer, PDCP layer) for data transmission between the terminal and the network. The establishment of the RB means a process of defining characteristics of a radio protocol layer and a channel to provide a specific service, and setting each specific parameter and operation method.

The RB can be divided into two types, a signaling RB (SRB) and a data RB (DRB). The SRB is used as a path for transmitting the RRC message in the control plane, and the DRB is used as a path for transmitting the user data in the user plane.

The non-access stratum (NAS) layer located above the RRC layer performs functions such as session management and mobility management.

On the other hand, the quality of each radio link changes rapidly and to some extent randomly within the cell of mobile radio communication, and this change must be considered in order to effectively operate the communication system.

A scheduler is one way to deal with this quality link change. The scheduler for the downlink is generally a round-robin scheduler in which terminals alternately use shared resources without considering the channel state, and the terminal with the absolute best downlink channel state is scheduled. -C / I scheduler (also known as maximum rate scheduler), a PF (Proportional-Fair) scheduler that allocates shared resources to the terminal with the highest radio link state but limits the long-term quality of service difference between terminals to a certain level or less. And the greedy filling scheduler, which is commonly used in non-orthogonal multiple access schemes.

Unlike the downlink in which the power resources are concentrated in the base station, in the uplink, the power resources are divided among the terminals. In addition, the maximum uplink transmission power of a single terminal is generally significantly lower than the output of the base station. In this regard, uplink scheduling may be different from downlink scheduling, but the above-described scheduling principles for downlink may also be applied to uplink.

Although there are various scheduling schemes, the scheduling algorithm or the scheduling strategy itself is generally a matter of (base station) implementation, so other standards, including 3GPP, do not specifically standardize it. However, almost all service providers attempt to effectively use radio resources in a cell while maintaining an appropriate quality of service (QoS) between users in base station construction and wireless communication system operation. Therefore, a terminal having a relatively advantageous channel condition by using a channel change between terminals while guaranteeing the same average user throughput for all terminals or a certain minimum user throughput for at least all terminals. Scheduling is the overall goal of most schedulers.

As such, there may be a significant gain in system capacity if the state of the channel is taken into account for scheduling. Scheduling according to channels is used in HSPA / HSUPA or LTE. In case of LTE, not only the channel change in the time domain but also the channel change in the frequency domain can be considered.

In case of scheduling according to the channel state in downlink, the terminal may transmit a channel-status report to the base station. The channel status report may include instantaneous channel quality in the time and / or frequency domain. In case of spatial multiplexing, information necessary for antenna processing may also be included in the channel status report.

The channel status report is a report regarding transmission settings and / or parameters determined by the terminal to be suitable for use when transmitting the DL-SCH to the corresponding terminal. The UE determines transmission configuration and / or parameters based on the downlink instantaneous channel state. The channel status report may be configured according to a setting, and may include one or more of the following indicators.

Rank indicator (RI) is an indicator transmitted only when the terminal supports spatial multiplexing, and provides information on the rank of the channel, that is, the number of layers desired to be used for downlink transmission to the terminal. do.

Precoder Matrix Indicator (PMI) is an indicator reported only when the UE is in a closed-loop spatial multiplexing mode and provides information on a precoder matrix that is desired to be used for downlink transmission. In this case, the reported precoder matrix is determined based on the number of layers reported through the rank indicator.

Channel-Quality Indicator (CQI) indicates a modulation scheme and coding rate that are desired to be used for downlink transmission.

The base station or network does not necessarily follow the manner in which these indicators recommand. For example, when the base station or the network follows the channel status report, the precoder only needs to confirm that the precoder setting indicated by the precoder matrix indicator is used for downlink transmission. If the base station or network does not follow the channel status report, information about the precoder used should be explicitly included in the downlink scheduling assignment.

In the case of LTE, the channel status report may be periodic or aperiodic. In aperiodic cases, when there is an explicit request from a base station or network, a channel status report is sent to the base station or network. The base station or the network may request a channel status report by including a flag for requesting a channel status report in an uplink scheduling grant or the like.

In the case of periodic channel status report, the channel status report is transmitted from the terminal to the base station or the network at a predetermined period. The above-mentioned different information, for example, rank indicator, precoder matrix indicator, channel quality indicator, etc., need not all be reported in the same period or the same number of times. In general, the periodic channel status report may be delivered to the base station or the network through the PUCCH physical channel.

Channel-based scheduling is generally used for downlink transmission, but channel-based scheduling may also be used for uplink transmission. In the case of scheduling according to the channel state in the uplink, a sounding reference signal (SRS) transmitted from each terminal may be generally used for estimating the channel quality at the base station.

As such, what is basically needed at the transmitting side is an estimate that reflects the channel state at the moment of transmission. That is, in order to schedule considering the instantaneous channel state, the instantaneous channel state information is required. However, the network must also know the state of communication within the cell for other purposes.

The terminal continuously or at a specific time point measures the communication quality of a serving cell currently providing a service and the communication quality of a neighbor cell around the serving cell.

The terminal transmits the communication quality of the measured cells to the network according to the requirements of the network, the terminal's own needs, or according to predetermined rules or instructions, and the network sends a handover command to the terminal based on the measured values reported by the terminal. You can also get off. In this way, the network can effectively support the mobility of the terminal by using the communication quality within and around the cell measured by the terminal.

5 is a conceptual diagram schematically illustrating a handover of a terminal between base stations in a system to which the present invention is applied.

As mentioned in the description of FIG. 1, the base stations 20 may be connected to each other through an X2 interface. The X2 interface is used by the base stations 20 to send and receive messages dynamically. The base station 20 is connected to an evolved packet system (EPS), more specifically, a mobility management entity (MME) / serving gateway (S-GW) 30 through an S1 interface. The S1 interface supports a many-to-many-relation between base station 20 and MME / S-GW 30.

The PDN-GW 40 is used to provide packet data services to the MME / S-GW 30. The PDN-GW 40 varies depending on the purpose or service of communication, and the PDN-GW 40 supporting a specific service can be found using APN information. These architectures and interfaces are based on 3GPP TS23.401 and TS23.402.

Inter-E-UTRAN handover is a basic handover mechanism used for handover between E-UTRAN access networks, and is composed of X2 based handover and S1 based handover.

X2-based handover is used when the UE wants to handover from a source base station (SeNB: Source BS) 21 to a target base station (TeNB: Target eNB) 22 using an X2 interface. In this case, the MME / S-GW (30) ) Does not change.

By S1 based handover, the first bearer established between the P-GW 40, the MME / S-GW 30, the source base station 21, and the terminal 10 is released, and P is released. A new second bearer is established between the GW 40, the MME / S-GW 30, the target base station 22 and the terminal 10.

FIG. 6 is a flowchart schematically illustrating a handover process of changing a base station when a terminal is connected to an LTE system using a single component carrier in a system to which the present invention is applied.

As described above, the UE continuously or at a specific time point measures the communication quality of a serving cell currently providing a service and the communication quality of a neighbor cell around the serving cell. The UE UE transmits a measurement report regarding the measurement result to the source base station SeNB (S610). The measurement report includes information determined according to the measurement report setting. For example, the measurement report may include a measurement value regarding a measurable cell state such as RSRP, RSRQ, etc. of the cell. The source base station (SeNB) determines whether handover is necessary through the measurement report received from the terminal.

If it is determined that the handover is necessary, the source base station transmits a message for requesting handover to the target base station TeNB (S620). The handover request message is a message for requesting preparation of necessary resources together with a request for handover to a target base station.

Receiving the handover request message, the target base station adopts handover admission control (Admission Control) which determines whether to accept or not handover in consideration of the current system load and radio conditions and / or the status of available resources. It performs (S630).

After determining whether to accept the handover, the target base station transmits a handover request ACK to the source base station (S640). The handover request response may include information on whether to allow or disallow handover to the corresponding UE.

The source base station determines whether to perform a handover based on information on whether to allow or disallow handover included in the handover request response received from the target base station (S650).

If it is determined to perform the handover, the source base station transmits a handover command (handover command) to the terminal (S660).

When the terminal receives the handover command from the source base station, it disconnects from the source base station cell and attempts to connect to the target cell (S690). At this time, the source base station transmits the context used by the terminal in the source base station to the target base station (S680).

In order to access the target cell, the UE performs operations required for access to the first and second layers, that is, a radio physical layer (PHY), a medium access control (MAC) layer, and a radio link control (RLC) layer. An operation required for the connection may include a random access operation using the RACH.

Random access is a terminal that fails to acquire or misses uplink synchronization using a random access channel (RACH) to achieve uplink time synchronization. The scenario in which the RACH is used is, for example, as follows. (1) UE that is in the RRC_CONNECTED state but is not uplink synchronized and needs to transmit new uplink data and control information, such as an event-triggered measurement report. (2) UE in the RRC_CONNECTED state, but is not uplink synchronized and needs to receive new subband data, and thus needs to transmit a corresponding ACK / NACK signal. (3) UE in the RRC_CONNECTED state, but handing over from the current serving cell to the target cell. (4) Transition from RRC_IDLE state to RRC_CONNECTED.

The terminal completes the connection with the target cell (S690). When the connection between the terminal and the target cell is completed, packet transmission and reception may be performed between the terminal and the target base station.

In addition to being used to support the mobility of the terminal as described above, the measurement values of the communication environment of the network measured by the terminal may be used to build and operate the network system.

In general, a network operator optimizes a network such as a base station or a cell environment by confirming whether a coverage is lost or coverage hold related to a wireless call quality or a cell radius of a terminal when constructing a wireless communication network. For example, the terminal may determine the location where the terminal can talk by identifying the strength of the base station signal, or the terminal may identify the location where the call becomes difficult due to the attenuation of the signal, thereby effectively coping with this. Alternatively, a measurement value of communication quality including signal strength of a base station may be used to identify a shaded area that is a location where a terminal cannot make a call and to solve the problem.

FIG. 7 is a conceptual diagram schematically illustrating a concept of a driving test for measuring wireless call quality and / or coverage using a vehicle in a system to which the present invention is applied. The network operator and the like move within the call area, that is, the cell, of the established base station 700 using the vehicle 710.

As can be seen in the movement path 720 of the vehicle 710, the vehicle 710 collects call quality of the corresponding area by using a terminal mounted while going through all possible places in the cell. The call quality within a cell varies due to various factors, such as the placement of buildings 730 within the cell or the top and bottom of the terrain. For example, there may be callable areas 740 and 750, while there may be call shadowed areas 760. Furthermore, there may be regions 740 with good call quality, and regions 750 with poor call quality, among the callable areas.

In general, call quality may vary depending on the distance from the base station 700. For example, the region 740 with good call quality is closer to the base station 600 than the region 750 with poor call quality, so it may be predicted that the call quality will be better in terms of transmission power. However, as mentioned above, call quality or call condition is affected by various factors. Given topographical influences, such as building 730, actual local call quality may be different than expected. For example, it may be the same, located between the buildings, not far from the base station, but in the call shading area 760.

Therefore, in order to actually optimize the network, detailed information about the communication environment in the network is required. This requires a lot of time and manpower to drive the test wherever needed in the cell.

Considering how to measure the quality of the communication environment in a network without having to measure the call quality by moving all the possible areas in the cell directly through a vehicle or the like. That is, a method of measuring call quality in the network while minimizing driving test (Minimization Driving Test: MDT, hereinafter referred to as 'MDT') may be considered.

FIG. 8 is a conceptual diagram schematically illustrating measuring a communication environment of a network, that is, wireless call quality and / or coverage, using MDT in a system to which the present invention is applied.

Minimize the measurement of the call quality in the cell while moving directly to the vehicle, etc., and confirm the wireless communication environment and the coverage situation through the communication quality at various locations in the cell measured and reported by each terminal. Similar to the actual driving test by using the values measured by terminals scattered in various regions, the region where the terminal can make a call or the region where the terminal cannot make a call due to signal attenuation, etc. are similar to the actual driving test. I can figure it out.

Referring to FIG. 8, by using a plurality of terminals 800 interspersed in a cell to measure wireless call quality, the measurement vehicle 710 only needs to travel a minimum path 760.

In addition to the measurements performed by the moving vehicle 710, measurements for the wireless environment are performed at multiple terminals in various locations within the cell. Each terminal can measure the radio environment according to the current location according to the MDT configuration.

At this time, the information measured by the terminal for the MDT wireless environment is called a log. The log may be a content that the terminal checks and stores in the memory the signal strength, the measurement position, the measurement time, etc. of the serving cell or the adjacent cell. The terminal may continuously accumulate logs and store them in a new log form whenever the state of the wireless communication environment is measured. The terminal may report to the network or the base station that it currently has a log (Log) accumulated by performing the MDT. When the terminal receives the log information from the network or the base station, the terminal may transmit the log information to the network or the base station.

9 is a flowchart schematically illustrating an MDT configuration method in a system to which the present invention is applied. The network configures MDT setting parameters (S910). In this case, the network is not a simple network or a core network, but a concept including all of a base station eNB or a base station 3GPP UTRAN, LTE E-UTRAN, WCDMA UMTS. Hereinafter, in the present specification, the network may not be a simple network or a core network, but may be used as a concept including all of a base station eNB or a base station 3GPP UTRAN, LTE E-UTRAN, WCDMA UMTS, and the like. Therefore, the MDT configuration parameter may be configured at the base station, or the MDT configuration parameter may be configured at the base station.

The MDT configuration parameters configured in the network include the measurement object of MDT measurement, the duration of MDT measurement, the period of MDT measurement, the report method of log, the reporting period of log, the time of base station, etc. It may contain information about.

The network may set, through a parameter about an object of MDT measurement, an object to be measured by the UE in order to obtain information about a communication state or call quality of the network. The MDT measurement target may be limited to the signal quality of the serving cell and may be set to include the strength of the signal transmitted from the base station of the neighboring cell as needed.

The network may set the duration of the MDT measurement and the period of measurement performed during the measurement period through parameters related to the duration and the period of the MDT measurement. In this regard, it may be set to perform the MDT measurement for a predetermined period and to terminate it, or may be set to perform the MDT measurement for a predetermined period periodically at regular intervals.

The network may set a method of transferring the result of the MDT measurement from the terminal to the network through a parameter related to a log reporting method. The reporting of the log information may take a manner in which the terminal reports the log information to the network when the network requests the report of the log to the terminal. The terminal may transmit to the network or the base station that it currently has a log accumulated through the MDT. The network may request the report of the log from the terminal after grasping the state of the log of the terminal received from the terminal. In addition, even if there is no explicit request from the network, after a certain time elapses after starting the MDT measurement, the terminal may take a method of reporting log information to the network. In addition, log information may be periodically reported at regular intervals.

When the network is configured to report the log information every fixed time, the network may set the report period of the log information through a parameter related to the report period of the log. In this case, the network may perform MDT for each of the above-described MDT measurement targets, and may set different reporting periods of log information for each MDT measurement target. In addition, the network may be configured to periodically report the log of some of the above-described MDT measurement targets, and some only to report when there is an explicit request from the network.

The network may set a reference time for the MDT measurement through a parameter regarding the time of the base station.

Although some parameters related to the MDT setting have been described herein, the parameters related to the MDT setting may be variously configured according to the needs of network optimization in addition to the above-described parameters. For example, in relation to the reporting method of the log, the log is reported only when there is an explicit request for reporting the log from the network. However, when there is no explicit request from the network, how to handle the log accumulated therein is described. You can also set parameters. In addition, an existing MDT configuration parameter may be modified or deleted, or a new MDT configuration parameter may be added to the existing MDT configuration parameter.

The base station includes the MDT setting value in a log configuration request message and transmits it to the terminal UE (S920). The log setting request message includes related information necessary for measuring the MDT in the terminal. The log setup request message may include an indicator to initiate the MDT measurement. The log setting request message may also be an indicator for initiating MDT measurement.

The log setting request message may include the MDT setting parameters as described above, for example, a measurement object of MDT measurement, a duration of MDT measurement, a period of MDT measurement, a report method of log, a log of It may be configured according to the MDT configuration parameters such as the reporting period, the time of the base station.

The UE may receive a log setting request message from the base station and set a log environment according to the MDT setting included in the received message (S930).

If log information is needed, the network may request log information from the terminal (S940). Upon receiving the log information request from the network, the terminal may create a log information report based on the created log (S950). Alternatively, the terminal stores the log obtained by logging according to the log setting request message and may use the stored log information as a log information report. Subsequently, the terminal may transmit the generated log information report to the network (S960). Here, the terminal has been described as delivering the log report to the network only when there is a log information request (request) from the network, the present invention is not limited to this, according to the preset conditions, the explicit log information request from the network Log information can be reported to the network even if it is not present.

MDT can be classified into IMDT (Immediate MDT) and LMDT (Logged MDT) according to a mode in which a measurement is performed. In both cases, the IMDT and the LMDT receive the MDT configuration in the RRC_CONNECTED mode.

 Regarding the measurement, in the case of IMDT, the UE performs the measurement in the RRC_CONNECTED mode. The UE of the RRC_CONNECTED mode performs the measurement according to the MDT configuration at a certain period. In addition, the UE in the RRC_CONNECTED mode may perform the measurement when the triggering event occurs according to the instruction of the base station or as predetermined. The terminal logs the measurement results. For example, the terminal may log when RLF (Radio Link Failure) occurs. The terminal may transmit to the base station that it is in a state that can report the log (report), through which the base station can determine that the terminal is in a state capable of MDT reporting. The base station may request the MDT report from the terminal. In the case of IMDT, the base station may transmit a message requesting an MDT report by including it in an information request message about measurement that the terminal generally performs, such as the channel information described above. The terminal receiving the MDT report request message transmits an MDT report message to the corresponding base station based on the measured log.

Regarding the measurement, in the case of the LMDT, the UE performs the measurement in the RRC_IDLE mode. The UE in the RRC_IDLE mode may perform the measurement at regular intervals according to the MDT configuration. For example, the UE may wake up every cycle that is set to a constant multiple of the 'On Duration' cycle of DRX, and may measure according to the MDT configuration. In addition, the terminal may perform the measurement when the triggering event occurs according to the instruction or predetermined by the base station. According to the MDT configuration, the terminal performing the measurement logs the measurement result. The UE in the RRC_IDLE mode may access the cell through, for example, a cell selection / reselection process. In this case, the terminal may transmit to the base station that it is in a state that can report the log (report) through the process of accessing the cell, through which the base station can determine that the terminal can be a state MDT reporting. The base station may request the MDT report from the terminal. The base station may include a message requesting the MDT report in the information request message and transmit the message. The terminal receiving the MDT report request message transmits an MDT report message to the corresponding base station based on the measured log.

In addition, the MDT may be classified into a periodic MDT and an event triggering MDT according to a method in which a measurement is performed.

10 is a conceptual diagram schematically illustrating an example of forming a log in periodic MDT in a system to which the present invention is applied.

Referring to FIG. 10, the terminal performs measurement for a network communication environment at every measurement time point T ₁ to T ₅ according to the MDT measurement period T _M during the MDT measurement period T _on . The MDT measurement period and / or MDT measurement period may be configured by the network as a setting parameter of the periodic MDT. In this case, the network is not a simple network or a core network, but a concept including all of a base station eNB or a base station 3GPP UTRAN, LTE E-UTRAN, WCDMA UMTS. Therefore, the parameters related to the MDT configuration may be configured at the base station or may be configured at the base station.

In the example of FIG. 10, the MDT measurement period T _M is set to a multiple of the paging DRX cycle T _d . In order to reduce power consumption in the terminal reception circuit, LTE supports Discontinuous Reception (DRX), and HSPA, etc., corresponds to a Continuous Packet Connectivity (CPC) function. If a DRX cycle is specified, the UE observes downlink control signaling in one subframe per DRX cycle and maintains a sleep mode in another subframe. In periodic MDT, this DRX cycle can be used as a reference for setting MDT measurement cycle.

The terminal measures the network communication environment according to the MDT setting, and creates a log, which is measurement information. At every measurement, the log is continuously accumulated and stored in the terminal in a new log form. As shown in the example of the log shown in FIG. 10, a log number according to a measurement time point may be displayed in the log to distinguish each log, a timestamp for a value of a measured wireless communication environment and a measurement time, Measurement location information and the like. Herein, it has been described as including a measurement value, a time stamp, and location information for a wireless communication environment. However, the present invention is not limited thereto, and each log may include various information as necessary.

In the case of the periodic MDT periodically operated as described above, the terminal measures the network communication quality and creates / stores / manages logs according to the preset period during the preset period.

With this periodic MDT, an event trigger MDT can be used to more accurately determine the call quality within the cell.

11 is a flowchart schematically illustrating a method for setting an event triggered MDT in a system to which the present invention is applied.

The network sets the method of event trigger MDT (S1110). In this case, the network is not a simple network or a core network, but a concept including all of a base station eNB or a base station 3GPP UTRAN, LTE E-UTRAN, WCDMA UMTS. Therefore, the parameters related to the MDT configuration may be configured at the base station or may be configured at the base station. The network may set the event trigger MDT to be set separately from the periodic MDT, or may set the event trigger MDT through the setting of the periodic MDT.

In the present specification, the network is used as a concept including all of a base station eNB or a base station 3GPP UTRAN, LTE E-UTRAN, WCDMA UMTS and the like.

The parameter configured to set the event trigger MDT may include information about a type of triggering event. In addition, the parameter configured to set the event trigger MDT may include information about logging and / or reporting log information.

There can be various triggering events for the MDT measurement, and the network can select the desired triggering event from among them. For example, when the location information of the terminal is updated as an event that can use the event trigger MDT, the network state measured by the terminal changes, the operation of the terminal or the operation of the base station may be considered.

The network includes the event trigger MDT configuration parameter in a log configuration request message and transmits it to the UE (S1120). The log setup request message may include an indicator to initiate an event trigger MDT measurement. In addition, the log setting request message may be an indicator for initiating event trigger MDT measurement. Here, the log setting request message has been described as including the event trigger MDT configuration parameter, but may be transmitted to the terminal by including the event trigger MDT configuration parameter in a message other than the log configuration request message. In addition, the network may configure and send a message including only the event trigger MDT configuration parameter to the terminal. When the network transmits the event trigger MDT configuration parameter, the network may separately notify the terminal of information about the transmission, if necessary.

The UE may set a log environment based on the message received from the network (S1130). If the received message includes only the parameters related to the event trigger MDT setting, a log environment based on the event trigger MDT setting may be set. If the received message is, for example, a log setting request message and includes a parameter related to the event trigger MDT setting, the log environment based on the MDT setting of the log setting request message is set and the log environment based on the event trigger MDT setting is set. Can be set.

If log information is needed, the network may request log information from the terminal (S1140). Upon receiving the log information request from the network, the terminal may create a log report based on the created log (S1150). Subsequently, the terminal delivers the generated log report to the network (S1160). The log report may be final log information stored through the log set by the terminal.

Herein, the terminal transmits a log report to the network when there is a log information request from the network. However, the present invention is not limited thereto, and according to a preset condition, even if there is no explicit log information request from the network. Log information can be reported to the network.

The event trigger MDT performs MDT measurement according to the occurrence of the above-described triggering event. When the triggering event occurs, the terminal may perform the MDT measurement and log according to a predetermined predetermined rule or instruction. Or, when a triggering event occurs, you can make MDT measurements and log only if there is a clear request from the network.

In the event triggering MDT, when the network requests a report of the log to the terminal, the terminal may report the log information to the network in response thereto. In addition, even if there is no explicit request from the network, log information may be reported after a certain time after the MDT measurement.

On the other hand, as described above, there are various triggering events in which the network may require MDT measurement, and the network may select a desired triggering event from among them. Hereinafter, as an example of a triggering event, (1) the case where the location information of the terminal is updated, (2) the case where the network state measured by the terminal changes, and (3) the case where the operation of the terminal or the operation of the base station fails.

(1) When the location information of the terminal is updated.

Methods for determining the location of the terminal can be largely divided into a network-based method and a handset-based method. The basic principles of the positioning method of the network-based method are Time Difference of Arrival (TDOA), Angle of Arrival (AOA) and RF Fingerprint (RF Fingerprint). There is a Time of Arrival (TOA) using a Global Positioning System (GPS). There is also a hybrid positioning method that combines the basic principles of such a positioning method.

The positioning method based on Observed TDOA (OTDOA), which measures the position by observing the relative difference of the radio wave arrival time from two signal sources, has been standardized. In LTE, a positioning method using an LTE Positioning Protocol (LPP) is used. In WCDMA, the position of the terminal can be confirmed using the terminal positioning method.

The terminal may have a connection or session for receiving location information or location update information, such as a network that provides a service based on position or positioning. Here, the network may be a server of a base station and / or location based service.

When the location information of the terminal changes, such as when the location is changed due to movement or the location information is newly received by the location information service, the terminal may acquire the changed location information through the above-described connection setting. do.

When the location information of the terminal is changed, the terminal may report this as a triggering event for MDT measurement and perform MDT measurement. The terminal performing the MDT measurement creates a log of the measured information. The log may include location information and time stamp at the time of measurement.

When the change of the location information is used as a triggering event, the terminal notifies the network, and receives a message including a parameter about the location information change as a parameter related to event triggering MDT setting from the network and performs MDT measurement. .

In addition, the MDT measurement may be performed using the location information change as a triggering event without receiving a message including a parameter regarding the location information change from the network. In this case, the network may transmit only an instruction to use the location information change as a triggering event instead of a parameter related to the location information change to the terminal so that the MDT measurement is performed.

In addition, when there is a predetermined rule or instruction between the terminal and the base station or between the terminal and the network that there is a change in the location information, the terminal acquires the change information of the location information and performs MDT measurement. It may be.

(2) triggering events based on measurements

The terminal continuously detects a wireless communication state such as signal strength or signal quality provided from the base station through measurement for a predetermined time or in a specific situation. Based on the continuous signal measurement operation of the terminal, the terminal or the network can identify a specific situation occurring in the terminal, and set the specific situation as a triggering event to perform MDT measurement and log the measured value as a log. I can write it. Which situation to view as the triggering event may be set in advance between the terminal and the network.

For example, the terminal may measure whether a triggering event occurs continuously using a DRX cycle. As shown in FIG. 10, when the period of measurement for the triggering event is set to a multiple of the DRX cycle, the terminal determines whether a condition that the triggering event has occurred is satisfied every cycle for checking the occurrence of the triggering event, and triggering When it is determined that an event has occurred, an event triggered MDT log may be generated. In this case, as a condition for determining that the triggering event has occurred, various values such as a threshold or an offset with respect to the preset triggering event may be used.

As a triggering event based on measurements, one can think of a change in the communication state of the network. The terminal may determine whether the measured value of the state of the network measured by the terminal, etc. is smaller or larger than a predetermined threshold value, and may be used as a condition for generating a triggering event for a network communication state change.

Hereinafter, when a measurement value for a network state of a serving cell or the like becomes larger than a predetermined threshold value, a value that is smaller than a predetermined threshold value and a difference that is larger than a predetermined offset in comparison with a measurement value for a neighboring cell are examples of triggering events. Explain.

-Triggering event 1: When the measured value of the network condition, etc. is larger than the predetermined threshold

The case where the measured value measured by the terminal regarding the network state or the like is larger than the predetermined threshold will be described as the triggering event 1. In this case, event triggered MDT configuration parameters include an event type, a threshold of the corresponding event type, a hysteresis value of the corresponding event type, and the like.

If the measured value is larger than the preset threshold value, it may be determined that the triggering event 1 has occurred.

Triggering event 1 may be used in various cases. For example, when the event type is a change in signal strength, the signal strength is measured by the mobile terminal, so that the boundary of the signal strength is changed from an area where the signal strength is weaker to an area where the signal strength is greater than or equal to a predetermined value, that is, a wireless communication network. Or it may be used to check the coverage of the cell. As such, if the event type is a change in signal strength, the predetermined signal strength may be set as a threshold, and whether or not a triggering event is generated may be determined by comparing the threshold and the measured value.

The event trigger MD configuration parameter, for example, an event type, a threshold value of the corresponding event type, a hysteresis value of the corresponding event type, and the like may be set in a network (base station or control station).

Triggering Condition 1 describes the triggering conditions.

(a) M _s ≥ Thresh or M _s > Thresh

In this case, M _s may be, for example, a reference signal received power (RSRP) or a reference signal received quality (RSRQ) as a measurement value of the corresponding event type for the serving cell, and Thresh is a corresponding event. The threshold for the type. In the case of the triggering condition (a), when the M _s value is greater than or equal to the threshold value, or when the M _s value is greater than the threshold value, the triggering event 1 is considered to have occurred.

(b) M _s -Hys> Thresh: Start event triggering

M _s + Hys <Thresh: End event triggering

In this case, M _s may be, for example, a reference signal received power (RSRP) or a reference signal received quality (RSRQ) as a measurement value of the corresponding event type for the serving cell, and Thresh is a corresponding event. The threshold for the type. Hys is the hysteresis value for that event type.

When the triggering condition (b) is used, the value of M _s Event triggering starts when the difference between hysteresis is greater than Thresh. Event triggering ends when the sum of M _s and hysteresis is less than Thresh.

Triggering event 2: When the measured value regarding the network status is smaller than the predetermined threshold

The case where the measured value measured by the terminal regarding the network state or the like is smaller than the predetermined threshold will be described as the triggering event 2. FIG. In this case, event triggered MDT configuration parameters include an event type, a threshold of the corresponding event type, a hysteresis value of the corresponding event type, and the like.

When the measured value is larger than the preset threshold value, it may be determined that the triggering event 2 has occurred.

Triggering event 2 may be used in various cases. For example, when the event type is a change in signal strength, the signal strength is measured by a moving terminal, so that the boundary of the signal strength is changed from an area where the signal strength is strong to an area where the signal strength is less than or equal to a predetermined value, that is, a wireless communication network or the corresponding. It may be used to check the coverage of the cell. As such, if the event type is a change in signal strength, the predetermined signal strength may be set as a threshold, and whether or not a triggering event is generated may be determined by comparing the threshold and the measured value.

The event trigger MD configuration parameter, for example, an event type, a threshold value of the corresponding event type, a hysteresis value of the corresponding event type, and the like may be set in a network (base station or control station).

Triggering condition will be described in Triggering Event 2.

(a) Ms ≤ Thresh or M _s <Thresh

In this case, M _s may be, for example, a reference signal received power (RSRP) or a reference signal received quality (RSRQ) as a measurement value of the corresponding event type for the serving cell, and Thresh is a corresponding event. The threshold for the type. In the case of the triggering condition (a), it is assumed that the triggering event 2 occurs when the M _s value is smaller than or equal to the threshold value, or when the M _s value is smaller than the threshold value.

(b) M _s + Hys <Thresh: Start event triggering

M _s -Hys> Thresh: End event triggering

In this case, M _s may be, for example, a reference signal received power (RSRP) or a reference signal received quality (RSRQ) as a measurement value of the corresponding event type for the serving cell, and Thresh is a corresponding event. The threshold for the type. Hys is the hysteresis value for that event type.

When the triggering condition (b) is used, the value of M _s Event triggering starts when the sum of hysteresis values is smaller than Thresh. Event triggering ends when the difference between M _s value and hysteresis value is larger than Thresh.

-Triggering event 3: When the measured value regarding the network state and the like is different from the measured value for the neighbor cell by more than a predetermined offset

A case in which the measured value measured by the terminal regarding the network state or the like is different from the measured value for the neighbor cell by more than a predetermined offset will be described as the triggering event 3. In this case, the event triggered MDT configuration parameter includes an event type, a predetermined offset value for the measurement of neighbor cells with respect to the corresponding event type, and the like.

The triggering event 3 may be used as an event for identifying a location and a time point at which the UE performs a handover from the serving cell to the neighbor cell, and the measurement value for the serving cell is preset in comparison with the measurement value for the neighbor cell. An event can be triggered if it is greater than a predetermined offset. For example, an event may be triggered when a measurement value regarding a network state measured while the terminal moves, for example, a measurement value for a strength of a radio signal is larger than that of a current serving cell.

The event trigger MD configuration parameter, for example, the event type, a predetermined offset value for the measurement of neighbor cells with respect to the event type, and the like can be set in the network (base station or control station) or the like.

Triggering condition is explained in triggering event 3.

(a) M _n ≥ M _s + Offset or M _n > M _s + Offset

In this case, M _s may be, for example, a reference signal received power (RSRP) or a reference signal received quality (RSRQ) as a measurement value of a corresponding event type for the serving cell, and M _n is M A measure of the neighbor cell for the same event type as _s . In addition, Offset is a predetermined offset value for the corresponding event type. If the triggering condition (a), the M _n values are considered as occurred in this case is greater than the offset value, than M _s or greater, or a M _n value is greater if the triggering event 3+ offset value than M _s.

(b) M _n -Hys> M _s + Offset: Start event

M _n + Hys <M _s + Offset: End event

In this case, M _s may be, for example, a reference signal received power (RSRP) or a reference signal received quality (RSRQ) as a measurement value of a corresponding event type for the serving cell, and M _n is M A measure of the neighbor cell for the same event type as _s . In addition, Offset is a predetermined offset value for the corresponding event type, and Hys is a hysteresis value for the corresponding event type.

In the case of using a triggering condition (b), M _n value and Hysteresis (hysteresis) of the difference value is greater than the sum of the value of M _s and the offset (Offset) triggering event is started, and the M _n value If the sum of the hysteresis values is less than the sum of the M _s values and the offset, the event triggering is terminated.

An example of an event that triggers a measurement of the network state of a serving cell or the like becomes larger than a predetermined threshold, a case in which the measurement becomes smaller than a predetermined threshold, and a difference that is greater than a predetermined offset compared to the measurement for a neighboring cell. As described above, the triggering event that can be used in the event triggered MDT method is not limited to this, and event trigger MDT measurement may be performed using various triggering events.

As described above, the MDT setting method can be largely divided into a periodic MDT method and an event triggered MDT method. In general, MDT uses a periodic MDT scheme. In addition, when it is necessary to more specifically understand the network environment according to a specific situation of the terminal or the network, the event trigger MDT method may be used. The periodic MDT method and the event trigger MDT method may be used alone or in combination. Therefore, in operating the MDT method, the MDT operation mode of the terminal may be divided into three modes as follows.

(1) Periodic (Type 1)

(2) Event triggered method (type 2)

(3) Mixed method of periodic method and event trigger method (Type 3)

The MDT operation mode may be set by the network in the MDT setting process. The network may transmit to the terminal which MDT operation mode should be set. In addition, the network may instruct to change only the set value while maintaining the same MDT mode of operation.

For example, in FIG. 9 and / or FIG. 11, the network configures MDT parameters (S910) or sets an event trigger MDT scheme (S1110), selects an MDT operation mode, and transmits information on this to a terminal or requests log setting. It may be included in a message and delivered to the terminal.

When the network determines that the MDT operation mode needs to be changed during or after the MDT measurement, or before and after the MDT measurement, the network configures a new MDT setting related parameter and includes the same in a log configuration request message. UE).

In addition, the network may configure a new MDT configuration parameter and transmit it to the terminal separately. In addition, when a specific situation occurs or a certain condition is satisfied according to a predetermined preset rule or indication, the terminal may change the MDT operation mode without an explicit indication from the network. Here, the predetermined preset rule or instruction may be included in the initial log setting request message and transmitted from the network to the terminal, or may be transmitted to the terminal when it is determined that a new condition or setting is necessary.

As described above, the MDT operation mode may be any one of operation modes classified as Type 1: Periodic Only, Type 2: Event Trigger Only, Type 3: Mixing of Periodic and Event Trigger. It can be one.

In this case, the network may configure information indicating any one of these three types and transmit the information to the terminal separately or include the information in the MDT mode of the log setting request message and transmit the information to the terminal. Upon receiving the information on the MDT operation mode, the UE may set a log environment according to the corresponding MDT operation mode (see S930 and S1130) and perform MDT measurement.

The above-described three MDT operation modes may be newly set as needed, or may be changed while the MDT measurement is in progress or before and after the MDT measurement.

Type 2 can be changed during or after MDT measurements with Type 1 or before or after MDT measurements. The terminal may end the periodic MDT configuration and perform the MDT measurement when a predetermined triggering event occurs.

Type 1 can be changed during or after MDT measurements with Type 1 or before or after MDT measurements. The terminal may perform the MDT measurement when a predetermined triggering event occurs while continuing the MDT measurement according to the periodic MDT setting.

Type 1 can be changed during or after MDT measurements with Type 2 or before or after MDT measurements. The terminal may terminate the event trigger MDT configuration and perform the MDT measurement according to the periodic MDT configuration.

The type 2 can be changed during or after the MDT measurement. The UE may perform the MDT measurement when the triggering event occurs according to the event trigger MDT setting, and may perform the MDT measurement according to the periodic MDT setting.

Type 1 can be changed during or after MDT measurements with Type 3 or before or after MDT measurements. The terminal may terminate the event trigger MDT configuration and the periodic MDT configuration, and perform the MDT measurement according to the new periodic MDT configuration. In addition, the terminal may terminate the event trigger MDT configuration only, and may perform the MDT measurement while maintaining only the periodic MDT configuration. The new periodic MDT setting may be the same as the existing periodic MDT setting. The new periodic MDT setting may be different from the existing periodic MDT setting.

Type 2 can be changed during or after MDT measurements with Type 3 or before or after MDT measurements. The terminal may terminate the event trigger MDT configuration and the periodic MDT configuration, and perform the MDT measurement according to the new event trigger MDT configuration. In addition, the terminal may terminate the periodic MDT configuration only, and may perform the MDT measurement while maintaining only the event trigger MDT configuration. The new event trigger MDT setting may be the same as the existing event trigger MDT setting. The new event trigger MDT setting may differ from the existing event trigger MDT setting.

Herein, a change in the MDT operation mode, that is, a case in which the MDT type is changed has been described. However, only the MDT setting may be changed while maintaining the same type.

FIG. 12 is a conceptual diagram schematically illustrating an example of creating a log in a mixture of a periodic method and an event trigger method in a system to which the present invention is applied.

Referring to FIG. 12, during the MDT measurement period T _on , the UE measures the network communication environment according to the periodic MDT setting at every measurement time point T ₁ to T ₅ according to the MDT measurement period T _M. Can be done. The measurement period of the periodic MDT and / or the measurement period of the MDT may be configured as a periodic MDT setting parameter. The measurement period or measurement period of the periodic MDT can be set variously as needed. In the example of FIG. 11, the measurement period T _M of the periodic MDT is set as a multiple of the paging DRX cycle T _d .

The terminal may measure a network communication environment or the like according to the periodic MDT setting, and create a log, which is measurement information. At every measurement, the log is continuously accumulated and stored in the terminal in a new log form. As shown in the example of the log shown in FIG. 12, the log includes a log number for distinguishing logs at each measurement, a timestamp for a value of a measured wireless communication environment, a measurement time, and a measurement position information. May be included. Herein, it has been described as including a measurement value, a timestamp, and location information for a wireless communication environment. However, the present invention is not limited thereto, and a log may include various information as necessary.

When the event is triggered, the terminal may measure the network communication environment according to the event triggered MDT setting, and create a log thereof. The log may be configured differently according to the type of triggering event. For example, when the triggering event is a change in the location information of the terminal, the log for the event trigger MDT may include the location information of the terminal and a time stamp at the time of measurement.

Logs for periodic MDTs and event triggers The logs for MDTs can be created / stored / managed / reported according to different settings in the terminal. In addition, the terminal may perform a log for the periodic MDT and the creation / storage / management / reporting of the log for the event trigger MDT according to some or all the same settings as necessary. For example, in case of the periodic MDT, if there is an explicit report request from the network, the event trigger MDT may report the log information to the network if a predetermined condition is satisfied even if there is no explicit report request from the network. It may be. In addition, in case of an event triggered MDT, the network may report to the network if there is an explicit report request, and in the case of a periodic MDT, log information may be reported to the network if a predetermined condition is satisfied without the network's explicit report request. have.

13 is a flowchart schematically illustrating the operation of a network for MDT measurement in a system to which the present invention is applied.

The network configures MDT setting parameters (S1310). In case of periodic MDT, the MDT configuration parameter is a measurement object of MDT, duration of MDT measurement, period of MDT measurement, report method of log, report period of log, time of base station And the like may be included. In addition, in the event trigger MDT, the MDT configuration parameter may include a type of a triggering event, information on logging, and / or reporting log information.

The network transmits a log setting request message including the MDT setting parameter (S1320). The network may determine whether it is necessary to change the MDT operation mode during the MDT measurement or before or after the MDT measurement (S1330). If it is determined that the change of the MDT operation mode is necessary, the network instructs the terminal to change the MDT operation mode (S1340). The instruction to change the MDT operation mode may be performed by creating and transmitting a new log setting request message or by transmitting a separate message to the terminal.

In relation to the change of the MDT operation mode, the changed MDT configuration may be delivered to the terminal by configuring a new MDT configuration parameter by the network and including the new MDT configuration parameter in a log configuration request message. . In addition, a new MDT configuration parameter may be configured by the network, and the new MDT configuration parameter may be transmitted to the terminal separately from the log configuration request message. In addition, the terminal may be configured to change the MDT setting according to a predetermined preset rule or indication. The predetermined rule or instruction may be included in the first log setting request message and transmitted from the network to the terminal, or may be transmitted to the terminal when the network determines that a new condition or setting is necessary.

In the present description, the network determines whether it is necessary to change the MDT operation mode, and accordingly, the instruction for changing the MDT operation mode has been described as being transmitted to the terminal. However, the present invention is not limited thereto, and the network uses one MDT operation mode. It is also possible to make MDT measurements.

After the MDT measurement is completed or while the measurement of the periodic MDT is being performed, the network may request a log report from the terminal (S1350), and if the terminal transmits a log report in response to the log report request, it is received (S1360). . Herein, the network explicitly requests and receives a log report from the terminal, but the present invention is not limited thereto, and the network is not limited to this. When the condition is satisfied, the log report may be received from the terminal.

14 is a flowchart schematically illustrating an operation of a terminal for MDT measurement in a system to which the present invention is applied.

The terminal receives a log setting request message from the network (S1410). In case of periodic MDT, the MDT configuration parameter is a measurement object of MDT, duration of MDT measurement, period of MDT measurement, report method of log, report period of log, time of base station And the like may be included. In addition, in the event trigger MDT, the MDT configuration parameter may include a type of a triggering event, information on logging, and / or reporting log information.

The terminal sets a log environment according to the MDT configuration parameter (S1420). For example, the terminal configures an environment in which the MDT measurement can be performed and logged according to the MDT configuration parameter.

Subsequently, the terminal may determine whether there is an instruction for changing the operation mode from the network or when a predetermined condition is achieved regarding the MDT operation mode change (S1430). If it is determined that the MDT operation mode needs to be changed, the MDT operation mode may be changed according to an instruction from the network or a predetermined condition set in advance (S1440).

Regarding the change of the MDT operation mode, the changed MDT setting is obtained by configuring a new MDT configuration parameter by the network and transmitting the new MDT configuration parameter to the UE by being included in a Log Configuration Request message. May be In addition, a new MDT configuration parameter may be configured by the network, and the new MDT configuration parameter may be transmitted to the terminal separately from the log configuration request message. In addition, the terminal may be configured to change the MDT setting according to a predetermined preset rule or indication. The predetermined rule or instruction may be included in the first log setting request message and transmitted from the network to the terminal, or may be transmitted to the terminal when the network determines that a new condition or setting is necessary.

The terminal performs MDT measurement in the corresponding MDT operation mode and creates / stores / manages a log (S1450). If the periodic MDT and the event trigger MDT is mixed, the terminal may create / store / manage / report the log for the periodic MDT and the log for the event trigger MDT according to different settings. In addition, the terminal may perform a log for the periodic MDT and the creation / storage / management / reporting of the log for the event trigger MDT according to some or all of the same settings as necessary.

After the MDT measurement and the creation / storage / management of the log, the terminal may again determine whether to change the MDT operation mode (S1460). When it is determined that the MDT operation mode needs to be changed, the MDT operation mode may be changed (S1440), and accordingly, MDT measurement and log writing / storing / management may be performed again (S1450).

Herein, the UE determines whether to change the MDT operation mode and explains that the MDT operation mode is changed accordingly. However, the present invention is not limited thereto, and the UE may perform MDT measurement while maintaining one MDT operation mode.

The terminal receives an MDT log reporting request from the network (S1470), and correspondingly transmits an MDT log report to the network (S1480). Although the present invention has been described as receiving a log report request from the network and correspondingly delivering the log report, the present invention is not limited thereto, and the terminal is not limited to an explicit log report request from the network according to a predetermined rule or instruction. A log report may be sent to the network when certain conditions are met.

Minimization Driving Test (MDT) minimizes driving test by using a user terminal in a cell. However, users continue to move with the terminal in the cell, and the terminal performing the MDT may change the base station outside the cell.

Currently, not all base stations support MDT, and even if all base stations support MDT in the future, all base stations may not support MDT in the same specification or in the same manner.

The terminal of the user performing the MDT may continue to measure and log according to the MDT configuration received from the conventional base station even though the terminal of the base station that supports the MDT leaves. In addition, the terminal of the user performing the MDT according to the MDT configuration of the conventional base station, even if entering the cell of the base station supporting the MDT different from the MDT configuration of the conventional base station, the measurement and logging (logging) according to the MDT configuration received from the conventional base station May continue.

By performing MDT measurement that does not need to be performed or continuing MDT measurement that does not conform to the setting, the user terminal unnecessarily consumes power and causes a waste of memory.

Therefore, when the user terminal performs the handover, it is necessary to control the MDT being performed. According to the MDT execution situation of the target base station, it is necessary to adjust the MDT measurement and / or MDT measurement log report of the user terminal. For example, the terminal may be adapted to a changed cell environment, such as changing the configuration of the terminal in advance based on whether the target base station supports MDT or MDT specification. In addition, the target base station may transmit the specification of the MDT currently in progress and / or the degree of MDT support of the terminal in advance to change the MDT setting of the terminal or stop performing unnecessary MDT.

MDT control according to handover may be performed together with a handover process between base stations and between a terminal and a base station.

Hereinafter, the MDT control method according to the handover, which is performed between the targets performing the handover, will be described with reference to the accompanying drawings.

<Source Base Station (SeNB) and Target Base Station (TeNB)-Use of Handover Preparation Procedure>

When handover is performed between base stations, the source base station and the target base station perform a handover preparation procedure such as S620 to S640 of FIG. 6. FIG. 15 is a flowchart schematically illustrating that an MDT control procedure is performed along with a handover preparation procedure performed between a source base station and a target base station. Message transmission and reception between the source base station and the target base station may be performed through the X2 interface, or may be performed through other wired or wireless channels.

As described with reference to FIG. 6, when the source base station receives the measurement report of the terminal and determines that handover is necessary, the source base station starts the handover preparation procedure (S1510).

In relation to the MDT control, the source base station transmits an MDT request message and / or an MDT configuration message to the target base station (S1520). Transmission of an MDT request message and / or an MDT configuration message may be included in a handover request message transmitted from a source base station to a target base station in a handover procedure.

The source base station may transmit an MDT request message to the target base station. The MDT request message determines whether or not to perform MDT in the target cell, and when the target base station receives the MDT request message, it determines that the MDT has been performed at the source base station and the source base station inquires whether the MDT will continue to be performed at the target cell. can do. The MDT request message may be configured as shown in Table 1, for example.

{  MDT_Release_Information Information about MDT version or release  MDT_Available_Flag Flag for MDT Availability }

Table 1 includes only information on the version or release of the MDT and a flag relating to whether or not the MDT is possible, but may include information on a corresponding terminal or MDT configuration information of the terminal acquired by the source base station in relation to the MDT. The target base station receives the MDT request information, and can also confirm that the source base station is currently performing the MDT, and the terminal that is the target of the handover is the terminal that supports the MDT.

When the source base station transmits only the MDT request message to the target base station, additional information required for performing the MDT, such as an MDT configuration message, may be transmitted to the terminal or obtained from the terminal after the handover is completed. .

The source base station may transmit the MDT configuration information together with the MDT request information to the target base station. In this case, the MDT related information may be configured as shown in Table 2.

{  MDT_Release_Information Information about the MDT version or release  MDT_Available_Flag MDT availability    {     Absolute_Time_Information Time information of cell     Logging_Duration Log progress     Logging_Interval Log progress interval     Area_Configuration Log Progress Area Information       Cell_Global_ID_List List of Logable Cell IDs       Tracking_Area_Code_List List of Logable Tracking Areas     MDT_PLMN_ID MDT-capable PLMN ID     MDT_Event_Triggered_List MDT Triggering Event List       MDT_Event_Type1 MDT Triggering Event Types       MDT_Event_Type2 MDT Triggering Event Types    } }

The MDT configuration message includes configuration information regarding the MDT that was performed in the source cell. For example, parameters relating to the time of the base station from which the reference time for MDT measurement and / or reporting can be known, parameters relating to the duration of the log progress, parameters relating to the log period or log interval, parameters relating to the region in which the MDT measurement is performed, The parameters may include parameters related to a public land mobile network (PLMN) ID capable of MDT, a parameter related to a list of triggering events, a parameter related to an MDT triggering event type, and the like. The source base station may transmit all of the information related thereto, or may transmit only necessary information according to the specification of the terminal, the specification of the target base station, the network status of the target base station, or the like, and may further include the necessary information.

The parameter regarding the list of the triggering event indicates information about the corresponding triggering event in the case of the event trigger MDT, and includes a parameter regarding the type of the MDT triggering event. As described above, the MDT triggering event may exist in various ways, and the network may select a desired triggering event from among them. For example, when the location information of the terminal is updated as an event that can use the event trigger MDT, the network state measured by the terminal changes, the operation of the terminal or the operation of the base station may be considered.

At this time, as shown in Table 2, the MDT configuration message may be transmitted together with the MDT request message, or may be transmitted without the MDT request message in Table 1. When only the MDT setup message is transmitted without the MDT request message, the target base station can determine that there is a request for performing the MDT from the source base station using only the MDT setup message and that the MDT is in progress at the source base station. In order to confirm the MDT request message and / or the MDT setup message, a requirement may be required that the target base station is at a certain level or higher, or has a function capable of supporting MDT. If the requirement is not met, the target base station may ignore the MDT request message and / or the MDT setup message.

The target base station checks the MDT request information and / or MDT configuration information included in the handover request message and examines the state of the MDT performed at the source base station (S1530). The checking of the MDT state by the target base station may be performed in the handover admission control step of the handover procedure.

The target base station determines whether the terminal needs to continue to perform the MDT performed by the source base station even after changing the base station to the target base station. MDT is a recent technology, and LTE base stations based on LTE Release 8 and 9 and earlier do not support MDT. If the target base station cannot support the MDT supported by the source base station, or if it is not necessary to perform the MDT in the cell environment of the target cell, it may not be necessary to proceed with the MDT. Here, the need not to perform the MDT means that it is not necessary to perform the MDT measurement and the log generation with the same settings as the MDT setting at the source base station.

In addition, base stations supporting MDT may not support MDT in the same manner and in the same manner. In addition, when the method of performing the MDT required in the cell environment of the target cell is different from that of the source base station, the MDT should be changed by changing the MDT configuration. For example, if a target base station requires or supports an MDT triggered by a particular event, while a periodic MDT has been performed at the source base station, the target base station may reset the MDT configuration to perform the event trigger MDT. In this case, the target base station may perform the necessary preparation by reviewing the MDT state based on the MDT request message and / or the MDT setting message transmitted from the source base station.

The target base station transmits an MDT Available Indication message and / or an MDT Reconfiguration message to the source base station based on the review of the MDT state (S1540). The MDT availability indication message and / or the MDT reset message may be transmitted in a handover request ACK message in a handover procedure.

The MDT availability indication message is an indicator as to whether the target base station continues to perform MDT. When the target base station decides to perform the MDT, the target base station may include the ACK information in the MDT availability indication message and transmit the same. The target base station may perform the MDT according to the MDT configuration of the source base station, or may perform the MDT by resetting the matters related to the MDT. If the MDT needs to be reset, the target base station may include only the ACK information in the MDT availability indicator and transmit the message, or may additionally transmit a message including the MDT reset information. When the target base station includes only the ACK information in the MDT availability indicator and transmits the necessary reset information, the handover may be directly transmitted to the terminal through the network.

If the target base station does not perform the MDT, it transmits including the NACK information in the MDT availability indication message. In addition, when the target base station is a base station that cannot process the MDT-related information, for example, when the MDT-related information is ignored as described above, the handover request response message may be transmitted without including the MDT availability indication message. In this case, the source base station may determine that the target base station does not support MDT.

The MDT availability indication message may be configured as shown in Table 3, for example.

{  MDT_Release_Information Information about the MDT version or release  MDT_Available_Indication MDT availability }

The target base station may transmit information on whether it is a base station capable of supporting the MDT through information on the MDT version or release, and whether the target base station will perform the MDT as described above through the flag indicating whether or not the MDT is available. It can convey information about it. Table 3 includes only the information on the version or release of the MDT and the indicator on whether the MDT is possible. For example, when the source base station transmits a message about the MDT by including the terminal information, the MDT related function of the corresponding terminal. It may further include information on whether it is supported by this target base station and / or information on required specifications and the like.

In addition, the target base station may include the MDT reset message together with the MDT availability indication message and transmit the message including the handover request response message. In this case, the MDT availability indication message and the MDT reset message may be configured as shown in Table 4.

{  MDT_Release_Information MDT version or release information  MDT_Available_Indication MDT availability    {     Absolute_Time_Information Time information of cell     Logging_Duration Log progress     Logging_Interval Log progress interval     Area_Information Log Progress Area Information       Cell_Global_ID Cell ID of the target cell       Tracking_Area_Code Tracking Area ID of Target Cell     MDT_PLMN_ID PLMN ID of the target cell     MDT_Event_Triggered_List List of MDT triggering event types desired by the target cell       MDT_Event_Type1 MDT Triggering Event Types       MDT_Event_Type2 MDT Triggering Event Types    } }

The MDT reset message includes configuration information about the MDT performed in or supported by the target cell. For example, parameters relating to the time of the base station from which the reference time for MDT measurement and / or reporting can be known, parameters relating to the duration of the log progress, parameters relating to the log period or log interval, parameters relating to the region in which the MDT measurement is performed, Parameters related to the cell ID of the target cell, parameters related to the tracking ID of the target cell, parameters related to the Public Land Mobile Network (PLMN) ID of the target cell, parameters related to the list of triggering events, parameters related to the MDT triggering event type, and the like. It may include. The target base station may transmit all of the information related thereto, or may transmit only necessary information according to the specification of the terminal, the specification of the target base station, the network status of the target base station, and the like, and may further include the necessary information.

The parameter regarding the list of the triggering event indicates information about the corresponding triggering event in the case of the event trigger MDT, and includes a parameter regarding the type of the MDT triggering event. As described above, the MDT triggering event may exist in various ways, and the network may select a desired triggering event from among them. For example, when the location information of the terminal is updated as an event that can use the event trigger MDT, the network state measured by the terminal changes, the operation of the terminal or the operation of the base station may be considered.

At this time, as shown in Table 4, the MDT reset message may be transmitted together with the MDT availability indication message, or may be transmitted without the MDT availability indication message in Table 3. When only the MDT reconfiguration message is transmitted without the MDT availability indication message, it is a case where the source base station can determine that the MDT has decided to perform the MDT from the target base station using only the MDT reconfiguration message.

The source base station determines whether the MDT continues in the target cell based on the MDT availability indication message and / or the MDT reset message transmitted by the target base station (S1550). This decision may be performed along with the handover decision on the handover procedure. The source base station may determine that the MDT continues in the target cell when the ACK information is included in the MDT availability indication message transmitted by the target base station. Also, the source base station may determine that the MDT continues in the target cell even when the target base station transmits an MDT reconfiguration message.

<Source base station (SeNB) and user terminal (UE)-handover>

FIG. 16 is a flowchart schematically illustrating that an MDT control procedure is performed along with a handover procedure performed between a terminal and a source base station in a system to which the present invention is applied.

As described above, the source base station checks whether the MDT continues in the target cell based on the MDT availability indication message and / or the MDT reset message transmitted by the target base station (S1610). This decision may be performed along with the handover decision on the handover procedure.

The source base station transmits an MDT availability indication message and / or an MDT reset message to the terminal (S1620). The MDT availability indication message and / or the MDT reset message transmitted from the source base station to the terminal may be included in the handover command or transmitted together with the handover command in the handover procedure. The handover command may be transmitted to the terminal through an RRC message transmitted from the base station to the terminal, for example, an RRC retransmission message.

The source base station may transmit the MDT availability indication message and / or MDT reset message transmitted by the target base station to the terminal as it is, and extract only the necessary portion or add necessary portions from the MDT availability indication message and / or MDT reset message. It can also be transmitted to the terminal with a change. For example, if information related to the MDT is not transmitted from the target base station and the source base station determines that the MDT cannot be performed in the target cell or the MDT does not need to be performed in the target cell, the MDT is stopped in the MDT availability indication message. Including information can be transmitted.

The MDT availability indication message transmitted from the source base station to the terminal may be configured as shown in Table 5, for example.

{  MDT_Available_Indication MDT availability }

The MDT availability indication message transmitted from the source base station to the terminal includes information on MDT availability. The information on whether the MDT is possible may be implemented by, for example, ACK information when the MDT is continuously performed in the target cell, and NACK information when the MDT cannot be performed in the target cell. The MDT availability indication message further includes information on whether the MDT configuration of the target base station is different from the MDT configuration of the source base station, whether the MDT configuration should be changed, the version or release of the target base station, etc., in addition to the MDT availability information. You may.

 When the source base station determines that the MDT continues in the target cell and transmits an MDT availability indication message to the terminal, the MDT reset message may be transmitted together. At this time, the MDT availability indication message and the MDT reset message may be configured, for example, as shown in Table 6.

{  MDT_Release_Information Information about the MDT version or release  MDT_Available_Indication MDT availability    {      Absolute_Time_Information Time of cell      Logging_Duration Log progress      Logging_Interval Log progress interval      Area_Information Log Progress Area Information        Cell_Global_ID Cell ID of the target cell        Tracking_Area_Code Tracking Area ID of Target Cell      MDT_PLMN_ID PLMN ID of the target cell      MDT_Event_Triggered_List List of MDT triggering event types desired by the target cell        MDT_Event_Type1 MDT Triggering Event Types        MDT_Event_Type2 MDT Triggering Event Types    } }

The MDT availability indication message transmitted from the source base station to the terminal may include information about which version or release the target base station is, as shown in Table 6. Since the information about the MDT resetting is necessary when the MDT continues to be performed in the target cell, the information about whether to enable MDT in this case may indicate that the MDT will continue to be performed in the target cell.

The MDT reset message includes configuration information about the MDT performed in or supported by the target cell. For example, parameters relating to the time of the base station from which the reference time for MDT measurement and / or reporting can be known, parameters relating to the duration of the log progress, parameters relating to the log period or log interval, parameters relating to the region in which the MDT measurement is performed, Parameters related to the cell ID of the target cell, parameters related to the tracking ID of the target cell, parameters related to the Public Land Mobile Network (PLMN) ID of the target cell, parameters related to the list of triggering events, parameters related to the MDT triggering event type, and the like. It may include. The source base station may transmit all of the information related thereto, or may transmit only necessary information according to the specification of the terminal, the specification of the target base station, the network status of the target base station, or the like, and may further include the necessary information.

The parameter regarding the list of the triggering event indicates information about the corresponding triggering event in the case of the event trigger MDT, and includes a parameter regarding the type of the MDT triggering event. As described above, the MDT triggering event may exist in various ways, and the network may select a desired triggering event from among them. For example, when the location information of the terminal is updated as an event that can use the event trigger MDT, the network state measured by the terminal changes, the operation of the terminal or the operation of the base station may be considered.

At this time, as shown in Table 6, the MDT reset message may be transmitted with the MDT availability indication message, or may be transmitted without the MDT availability indication message in Table 6. Even if only the MDT reset message is transmitted without the MDT availability indication message, the UE may determine that the MDT will be performed in the target cell by the new MDT setting included in the MDT reset message.

The terminal may receive the MDT availability indication message and / or the MDT reset message from the source base station, and maintain the MDT configuration, stop the MDT, or change the MDT configuration based on this (S1630).

As described above, when the source base station has indicated that it is not necessary to proceed with the MDT on the MDT availability indication message, the MDT measurement and / or log generation may be stopped after the handover is completed. In this case, the disposition of the log measured and produced so far can be transmitted or discarded to the base station according to the instruction of the network / base station, and can be stored.

When the source base station instructs to continue the MDT on the MDT availability indication message, the terminal may continue to perform the MDT while maintaining the current MDT configuration.

When the MDT reset message is transmitted together with the MDT availability indication message, or when only the MDT reset message is transmitted, the terminal may change or prepare to change the MDT setting even before completing the handover in order to continue performing the MDT.

In addition, even when the MDT reset message is not transmitted together and only an instruction to continue the MDT on the MDT availability indication message is transmitted, after the handover to the target base station is completed, the terminal is configured according to the MDT state of the target base station. You can change it.

In addition, even when the MDT reset message and the MDT availability indication message are not transmitted to the terminal, the MDT control for the terminal may be set by the network / base station in advance. For example, when handover is performed without transmitting the MDT reset message and the MDT availability indication message, the MDT setting may be maintained and the MDT may be continuously performed. On the contrary, when the handover is performed without transmitting the MDT reset message and the MDT availability indication message, the MDT may be stopped.

The UE may continue to perform the MDT after the handover or stop the MDT after the handover based on the MDT execution stop message of the source base station according to the configuration to be changed.

Hereinafter, a method of performing MDT control for each subject performing a handover procedure will be described with reference to the drawings.

FIG. 17 is a flowchart schematically illustrating MDT control performed by a source base station when performing a handover procedure in a wireless communication system to which the present invention is applied.

Referring to FIG. 17, the source base station receives a measurement report from the terminal (S1710). The source base station determines whether a handover for the terminal is necessary based on the measurement report from the terminal.

If it is determined that handover is necessary, the source base station transmits an MDT request message and / or an MDT configuration message to the target base station (S1720). Transmission of the MDT request message and / or MDT setup message may be included in a handover request message transmitted from the source base station to the target base station in the handover procedure.

The source base station receives an MDT availability indication message and / or an MDT reset message including information determined by the target base station about the MDT based on the MDT request message and / or the MDT setup message (S1730). The MDT availability indication message and / or the MDT reset message may be included in a handover request ACK message and transmitted from the target base station in a handover procedure. The MDT availability indication message includes information on whether MDT is to be continuously performed in the target cell. The MDT resetting message includes information on the DMT setting of the target base station when the MDT continues in the target cell and the MDT setting of the target base station and the source base station is different.

The source base station determines whether the MDT continues in the target cell based on the MDT availability indication message and / or the MDT reset message (S1740). This decision may be performed along with the handover decision on the handover procedure.

The source base station constructs an availability indication message and / or an MDT reconfiguration message including information on whether the MDT will continue in the target cell and transmits it to the terminal (S1750). The MDT availability indication message and / or the MDT reset message transmitted from the source base station to the terminal may be included in the handover command or transmitted together with the handover command in the handover procedure. The handover command may be transmitted to the terminal through an RRC message transmitted from the base station to the terminal, for example, an RRC retransmission message. The MDT availability indication message and / or MDT reset message may be transmitted to the terminal as it is transmitted by the target base station, or may be transmitted by extracting or adding necessary information by the source base station.

18 is a flowchart schematically illustrating MDT control performed by a target base station when performing a handover procedure in a wireless communication system to which the present invention is applied.

The target base station receives an MDT request message and / or an MDT setup message from the source base station (S1810). Transmission of the MDT request message and / or MDT setup message may be included in a handover request message transmitted from the source base station to the target base station in the handover procedure.

The target base station checks the MDT request information and / or MDT configuration information included in the handover request message and examines the state of the MDT performed at the source base station (S1820). The checking of the MDT state by the target base station may be performed in the handover admission control step of the handover procedure.

The target base station sets an MDT availability indication message and / or an MDT reset message based on the review of the MDT state, and transmits it to the source base station (S1830). The MDT availability indication message and / or the MDT reset message may be transmitted as included in the handover request response message in the handover procedure.

19 is a flowchart schematically illustrating an MDT control performed by a terminal when performing a handover procedure in a wireless communication system to which the present invention is applied.

The terminal continuously or at a specific time point measures the communication quality of a serving cell currently providing a service and the communication quality of a neighbor cell around the serving cell. The terminal UE transmits a measurement report regarding the measurement result to the source base station SeNB (S1910). The measurement report includes information determined according to the measurement report setting. For example, the measurement report may include a measurement value regarding a measurable cell state such as RSRP, RSRQ, etc. of the cell.

The terminal receives an MDT availability indication message and / or an MDT reset message from the source base station (S1920). The MDT availability indication message and / or the MDT reset message may be included in the handover command or received with the handover command in the handover procedure.

The terminal may maintain the MDT configuration, stop the MDT, or change the MDT configuration based on the MDT availability indication message and / or the MDT reset message received from the source base station (S1930).

20 is a block diagram illustrating a wireless communication system in which an embodiment of the present invention is implemented.

Referring to FIG. 20, the base station 2000 may be a source base station or a target base station. The base station 2000 includes a processor 2010, an RF unit 2020, and a memory 2030. The processor 2010 implements the proposed functions, processes and / or methods. According to the present invention, the processor 2010 transmits information on whether the base station can support the MDT using information on the MDT version or release. Alternatively, information on whether to perform MDT may be transmitted using a flag regarding whether MDT is available. Alternatively, information related to the MDT support and / or required information may be further configured to be transmitted through the RF unit 2020. At this time, the RF unit 2020 configures a handover request message (MDT availability indication message) or an MDT reset message to transmit the MDT related information.

Here, the relevant information for the MDT support, information about the time of the base station, information about the period of the log proceeding for MDT, information about the log period / interval, and the region (AREA) for performing the MDT measurement The information may further include at least one of information on information on a Public Land Mobile Network (PLMN) capable of MDT, information on a list of MDT triggering events, and information on an MDT triggering event type.

Layers of the air interface protocol may be implemented by the processor 2010. The memory 2030 is connected to the processor 2010 and stores various information for driving the processor 2010. The RF unit 2030 is connected to the processor 2010 and transmits and / or receives a radio signal.

The user terminal 2040 includes a processor 2050, an RF unit 2060, and a memory 2070. The processor 2050 implements the proposed functions, processes and / or methods. For example, according to the present invention, the processor 2050 may continuously or at a specific time point determine a communication quality of a serving cell currently providing a service and a communication quality of a neighbor cell around the serving cell. After the measurement, the measurement report (Measurement Report) for the measurement result (Measurement Report) or log report for the MDT measurement according to the invention can be performed (log report). In this case, the measurement report may include a measurement value regarding a measurable cell state such as RSRP and RSRQ of the cell.

In addition, the MDT configuration may be maintained, the MDT may be stopped, or the MDT configuration may be changed based on the MDT availability indication message and / or the MDT reset message received from the base station. In addition, in relation to the MDT measurement, the MDT triggering event type, MDT version or release information may be transmitted. Here, the information related to the MDT measurement, information about the period of the log proceeding for the MDT, information about the log period / interval, information about the area (AREA) for performing the MDT measurement, information about the UE The method may further include at least one of information on a list of MDT triggering events and information on an MDT triggering event type.

In this case, the RF unit 2060 may receive the MDT related information through a handover request message (MDT availability indication message) or an MDT reset message.

Layers of the air interface protocol may be implemented by the processor 2050. The memory 2070 is connected to the processor 2050 and stores various information for driving the processor 2050. The RF unit 2060 is connected to the processor 2050 and transmits and / or receives a radio signal.

The processors 2010 and 2050 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device as a processor. The memories 2030 and 2070 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. The RF unit 2020 and 2060 may include a baseband circuit for processing a radio signal.

Control information transmitted from the upper layer described in the present invention may be transmitted in a separate physical control channel, and may be updated periodically or aperiodically at the request of a base station or a terminal or according to a predetermined rule or indication. .

In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (16)

A method for processing a Minimization Driving Test (MDT) of a source base station during handover in a wireless communication system,
If it is determined that handover is necessary based on the measurement report received from the terminal performing the MDT, transmitting a first MDT message regarding the MDT to the target base station;
Determining whether the MDT is to be continued at the target base station based on the second MDT message transmitted by the target base station in response to the first message; And
And transmitting a third MDT message to the terminal based on the determination. The method of claim 1, wherein the first MDT message,
MDT information of the source base station and the MDT processing method of the source base station, characterized in that it comprises at least one of the indicator indicating whether or not. The method of claim 2, wherein the MDT information of the source base station,
MDT version / release information of the source base station, information on the time of the source base station, information on the duration of the log, information on the log period / interval, information on the region to perform the MDT measurement, PLMN capable of MDT (Public Land Mobile Network) MDT processing method of the source base station, characterized in that it comprises at least one of information on the ID, information on the list of the MDT triggering event, information on the MDT triggering event type. The method of claim 1, wherein the second MDT message,
And at least one of an indicator indicating whether the target base station can perform the MDT information and the MDT. The method of claim 4, wherein the MDT information of the target base station,
And at least one of MDT version / release information of the target base station and MDT resetting information according to the MDT setting of the target base station. The method of claim 5, wherein the MDT resetting information includes information on the time of the target base station, information on the duration of the log progress, information on the log period / interval, information about the region to perform the MDT measurement, cell ID of the target cell At least one of information about the information, a tracking ID of the target cell, information on a Public Land Mobile Network (PLMN) ID of the target cell, information on a list of MDT triggering events, and information on an MDT triggering event type. MDT processing method of source base station. The method of claim 1, wherein the third MDT message,
And at least one of information indicating whether to perform the MDT in the target base station and MDT resetting information according to the MDT setting of the target base station. The method of claim 7, wherein the MDT reset information,
Information on the time of the target base station, information on the duration of the log, information on the log period / interval, information on the area to perform the MDT measurement, information on the cell ID of the target cell, tracking ID of the target cell And at least one of information on a Public Land Mobile Network (PLMN) ID of a target cell, information on a list of MDT triggering events, and information on an MDT triggering event type. The method of claim 1, wherein the third MDT message is the same as the second MDT message. The method of claim 1, wherein if the second MDT message is not received from the target base station, determining that the MDT is not performed in the target cell, and transmitting the third MDT message to the terminal based on the determination. MDT processing method of the source base station. The method according to claim 1, wherein at least one of the step of transmitting the first MDT message, the step of determining whether to continue the MDT, and the step of transmitting the third MDT message is performed together with a handover procedure. A method for processing a Minimization Driving Test (MDT) of a target base station during handover in a wireless communication system,
Reviewing the MDT status based on a first MDT message including at least one of the MDT configuration information of the source base station and an MDT follow-up request received from the source base station; And
And transmitting a second MDT message including at least one of MDT follow-up information and MDT reset information based on the MDT status review. The method of claim 12, wherein the target base station does not transmit the second MDT message when the target base station cannot process the first MDT message received from the source base station. The method of claim 12, wherein at least one of the MDT status review step and the second MDT message transmission step is performed together with a handover procedure. A method for processing a Minimization Driving Test (MDT) of a terminal during handover in a wireless communication system,
Transmitting a predetermined measurement report to a source base station; And
And modifying the MDT setting based on an MDT message including at least one of an instruction regarding whether to continue MDT in the target cell received from the source base station and MDT reset information. The method of claim 15, wherein the MDT setting change comprises changing the MDT setting to any one of maintaining MDT setting, stopping MDT, and resetting MDT.

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