KR20210089961A - Method and appartus to log inoformation for access network optimization in wireless communication - Google Patents

Abstract

The present disclosure relates to a method of processing information for network optimization in a next-generation mobile communication system and an apparatus thereof. According to one embodiment, the method of operating a terminal in a wireless communication system includes the following steps of: counting and storing the number of first consecutive connection establishment failures in a first cell; counting and storing the number of second consecutive connection establishment failures in a second cell after a transfer from the first cell to the second cell; counting and storing the number of third consecutive connection establishment failures in the first cell after a transfer from the second cell to the first cell; and reporting at least one among the number of first consecutive connection establishment failures, the number of second consecutive connection establishment failures, and the number of third consecutive connection establishment failures to a base station after the establishment of the connection with the first cell. Therefore, the present invention is capable of performing network optimization in a wireless communication system.

Description

A method and apparatus for processing information for network optimization in a next-generation mobile communication system {METHOD AND APPARTUS TO LOG INOFORMATION FOR ACCESS NETWORK OPTIMIZATION IN WIRELESS COMMUNICATION}

The present disclosure relates to a wireless communication system, and to a method and apparatus for processing information for network optimization in a next-generation mobile communication system.

4G (4 ^th generation) to meet the traffic demand in the radio data communication system increases since the commercialization trend, efforts to develop improved 5G (5 ^th generation) communication system, or pre-5G communication system have been made. For this reason, the 5G communication system or the pre-5G communication system is called a system after the 4G network (Beyond 4G Network) communication system or the LTE system after (Post LTE). In order to achieve high data rates, 5G communication systems are being considered for implementation in very high frequency (mmWave) bands (eg, 60 gigabytes (70 GHz) bands). In order to mitigate the path loss of radio waves and increase the propagation distance of radio waves in the very high frequency band, in the 5G communication system, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) are used. ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed. In addition, for network improvement of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), an ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and reception interference cancellation Technology development is underway. In addition, in the 5G system, Hybrid FSK and QAM Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), which are advanced coding modulation (ACM) methods, and Filter Bank Multi Carrier (FBMC), NOMA, which are advanced access technologies, (non-orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.

On the other hand, the Internet is evolving from a human-centered connection network where humans create and consume information to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers, etc. with IoT technology, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between objects and a machine to machine communication (Machine to Machine) are required. , M2M), and MTC (Machine Type Communication) are being studied. In the IoT environment, an intelligent IT (Internet Technology) service that collects and analyzes data generated from connected objects and creates new values in human life can be provided. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliance, advanced medical service, etc. through the convergence and complex between existing IT (information technology) technology and various industries. can be applied to

Accordingly, various attempts are being made to apply the 5G communication system to the IoT network. For example, technologies such as sensor network, machine to machine (M2M), and MTC (Machine Type Communication) are being implemented by 5G communication technologies such as beamforming, MIMO, and array antenna. . The application of a cloud radio access network (cloud RAN) as the big data processing technology described above is an example of convergence of 3eG technology and IoT technology.

As described above, with the development of a wireless communication system, a method for processing information for network optimization is required.

Based on the above discussion, the present disclosure provides a method and apparatus for processing information for network optimization in a wireless communication system.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description. will be able

A method of operating a terminal in a wireless communication system according to an embodiment includes counting and storing the number of consecutive first connection establishment failure attempts in a first cell, after moving from the first cell to the second cell, Counting and storing the number of consecutive failed attempts to establish a second connection in the second cell, and after moving from the second cell to the first cell again, counting the number of consecutive failed attempts to establish a third connection in the first cell and storing the successive number of failed first connection establishment attempts, the number of consecutive failed attempts to establish a second connection, or the successive third connection establishment attempts, which are stored after being established with the first cell. It may include reporting at least one or more of the number of failures to the base station.

According to an embodiment of the present disclosure, network optimization may be performed in a wireless communication system.

1A is a diagram showing the structure of a next-generation mobile communication system.
1B is a diagram for explaining a wireless connection state transition in a next-generation mobile communication system.
1C is a diagram for describing a technique for collecting and reporting cell measurement information according to an embodiment of the present disclosure.
1D is a diagram illustrating a method of collecting and reporting cell measurement information according to an embodiment of the present disclosure.
1E is a flowchart of an operation for collecting and reporting cell measurement information according to an embodiment of the present disclosure.
1F is a diagram for explaining a cell ID in a next-generation mobile communication system according to an embodiment of the present disclosure.
1G is a flowchart of a terminal storing cell ID information according to an embodiment of the present disclosure.
1H is a flowchart of a terminal storing PLMN information according to an embodiment of the present disclosure.
1I is a flowchart of a terminal for storing information on the number of establishment failures according to an embodiment of the present disclosure.
1J is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present disclosure.
1K is a block diagram illustrating a configuration of a base station according to an embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to more clearly convey the gist of the present disclosure without obscuring the gist of the present disclosure by omitting unnecessary description.

For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings. In addition, the size of each component does not fully reflect the actual size. In each figure, the same or corresponding elements are assigned the same reference numerals.

Advantages and features of the present disclosure, and a method of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms, only the embodiments of the present disclosure make the present disclosure complete, and common knowledge in the technical field to which the present disclosure belongs It is provided to fully inform those who have the scope of the disclosure, and the present disclosure is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

At this time, it will be understood that each block of the flowchart diagrams and combinations of the flowchart diagrams may be performed by computer program instructions. These computer program instructions may be embodied in a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions performed by the processor of the computer or other programmable data processing equipment are not described in the flowchart block(s). It creates a means to perform functions. These computer program instructions may also be stored in a computer-usable or computer-readable memory that may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus the computer-usable or computer-readable memory. It may also be possible for the instructions stored in the flow chart block(s) to produce an article of manufacture containing instruction means for performing the function described in the flowchart block(s). The computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other programmable data processing equipment. It may also be possible for instructions to perform the processing equipment to provide steps for performing the functions described in the flowchart block(s).

Additionally, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). It should also be noted that in some alternative implementations it is also possible for the functions recited in blocks to occur out of order. For example, two blocks shown one after another may in fact be performed substantially simultaneously, or it may be possible that the blocks are sometimes performed in the reverse order according to a corresponding function.

At this time, the term '~ unit' used in this embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and '~ unit' performs certain roles do. However, '-part' is not limited to software or hardware. The '~ unit' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Accordingly, according to some embodiments, '~ part' refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, and programs. Includes procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, components and '~ units' may be implemented to play one or more CPUs in a device or secure multimedia card. Also, according to some embodiments, '~ unit' may include one or more processors.

Hereinafter, the operating principle of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description of the present disclosure, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present disclosure, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present disclosure, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

Hereinafter, the base station, as a subject performing resource allocation of the terminal, is at least one of gNode B (gNB), eNode B (eNB), Node B, base station (BS), radio access unit, base station controller, or a node on the network. can The terminal may include a user equipment (UE), a mobile station (MS), a terminal, a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. Of course, it is not limited to the above example.

A term for identifying an access node used in the following description, a term referring to network entities, a term referring to messages, a term referring to an interface between network objects, and a term referring to various identification information and the like are exemplified for convenience of description. Therefore, it is not limited to the terms used in the present disclosure, and other terms referring to objects having equivalent technical meanings may be used.

For convenience of description, in the present disclosure, terms and names defined in standards for 5G, NR, and LTE systems are used. However, the present disclosure is not limited by these terms and names, and may be equally applied to systems conforming to other standards.

That is, in describing the embodiments of the present disclosure in detail, the 3GPP will mainly focus on the communication standard set by the standard, but the main gist of the present disclosure is to greatly extend the scope of the present invention to other communication systems having a similar technical background. It can be applied with some modifications within the scope not departing from, which will be possible at the judgment of a person skilled in the art of the present disclosure.

1A is a diagram showing the structure of a next-generation mobile communication system.

Referring to FIG. 1A, as shown, the radio access network of a next-generation mobile communication system (5G or New Radio, NR) includes a next-generation base station (New Radio Node B, hereinafter gNB) (1a-10) and AMF (Access and Mobility Management) Function, 1a-05) or NR CN (New Radio Core Network) or NG CN (Next Generation Core Network). A user terminal (New Radio User Equipment, hereinafter NR UE or terminal, 1a-15) accesses an external network through gNB (1a-10) and AMF (1a-05).

In FIG. 1A , gNBs 1a-10 correspond to an Evolved Node B (eNB) of an LTE system. The gNB 1a-10 is connected to the NR UE 1a-15 through a radio channel and can provide a service superior to that of the existing Node B (1a-20). In the next-generation mobile communication system, since all user traffic is serviced through a shared channel, a device for scheduling by collecting status information such as the buffer status of the UEs, the available transmission power status, and the channel status is required. 1a-10) is in charge. One gNB 1a-10 can control a plurality of cells, and can be composed of a central unit (CU) in charge of control and signaling and a distributed unit (DU) in charge of transmitting and receiving signals. Next-generation mobile communication system (5G or NR). In order to implement ultra-high-speed data transmission compared to the LTE system, it may have a maximum bandwidth greater than or equal to the existing maximum bandwidth, and additionally beamforming technology may be applied by using Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology. In addition, an adaptive modulation & coding (AMC) scheme for determining a modulation scheme and a channel coding rate according to the channel state of the terminal may be applied. The AMF 1a-05 performs functions such as mobility support, bearer setup, QoS setup, and the like. The AMF (1a-05) is a device in charge of various control functions as well as a mobility management function for the terminal, and is connected to a plurality of base stations. In addition, the next-generation mobile communication system (5G or NR) may be linked with the LTE system, and the AMF (1a-05) is connected to the MME (1a-25) through a network interface. The MME (1a-25) is connected to the existing base station eNB (1a-30). A UE supporting LTE-NR Dual Connectivity (EN-DC) may transmit and receive data while maintaining a connection to not only the gNB 1a-10 but also the eNB 1a-30 (1a-35).

1B is a diagram for explaining a wireless connection state transition in a next-generation mobile communication system.

The next-generation mobile communication system has three radio access states (RRC states). The connected mode (RRC_CONNECTED, 1b-05) is a wireless connection state in which the terminal can transmit and receive data. The standby mode (RRC_IDLE, 1b-30) is a radio access state in which the terminal monitors whether paging is transmitted to itself. These two modes (1b-05, 1b-30) are radio access states that are also applied to the LTE system, and the detailed technology is the same as that of the LTE system. In the next-generation mobile communication system, a newly defined inactive (RRC_INACTIVE) radio connection state (1b-15) is defined. In the radio access state (1b-15), the UE context is maintained in the base station and the terminal, and RAN (Radio Access Network) based paging is supported. The characteristics of these new wireless access states are listed below.

- Cell re-selection mobility;

- CN - NR RAN connection (both C/U-planes) has been established for UE;

- The UE AS context is stored in at least one gNB and the UE;

- Paging is initiated by NR RAN;

- RAN-based notification area is managed by NR RAN;

- NR RAN knows the RAN-based notification area which the UE belongs to;

The INACTIVE radio access state, which is the new radio access state 1b-15, may transition to a connected mode or a standby mode using a specific procedure. For example, according to the Resume process, the INACTIVE mode is converted to the connected mode, and the connected mode is converted to the INACTIVE mode by using the Release procedure including the suspend configuration information (1b-10). This procedure may be accomplished by transmitting and receiving one or more RRC messages between the terminal and the base station, and may consist of one or more steps. In addition, it is possible to switch from INACTIVE mode to standby mode through the Release procedure after Resume (1b-20). Switching between connected mode and standby mode follows LTE technology. That is, through the establishment or release procedure, the mode conversion is made (1b-25).

1C is a diagram for describing a technique for collecting and reporting cell measurement information according to an embodiment of the present disclosure.

When constructing or optimizing a network, a mobile communication service provider measures signal strength in a typical expected service area, and then goes through a process of deploying or re-adjusting base stations in the service area based on this. The operator loads the signal measurement equipment on the vehicle and collects the cell measurement information in the expected service area, which requires a lot of time and money. This process is commonly referred to as a drive test, using a vehicle. In order to support operations such as cell reselection, handover, and serving cell addition when the UE moves between cells, the UE is equipped with a function of measuring a signal with the base station. Therefore, instead of the drive test, a terminal in the service area can be used, which is called minimization of drive test (MDT). The operator can set the MDT operation to specific terminals through various components of the network, and these specific terminals are in connected mode (RRC_Connected), standby mode (RRC_Idle) or inactive mode (RRC_Inactive) from the serving cell and neighboring cells. Collect and store signal strength information. Furthermore, various information such as location information, time information, and signal quality information may be stored together. The stored information may be reported to the network and delivered to a specific server when the corresponding terminals are in the connected mode.

MDT operation is largely classified into immediate MDT and logged MDT.

Immediate MDT is characterized by reporting the collected information directly to the network. In Immediate MDT, since the UE must immediately report the collected information, only the connected mode UE can perform this. In general, the RRM measurement process for supporting operations such as handover and serving cell addition is recycled, and location information and time information are additionally reported.

Logged MDT is characterized in that the collected information is stored without directly reporting to the network, and after the terminal switches to the connected mode, the stored information is reported. In general, a terminal in a standby mode that cannot directly report to the network performs a Logged MDT operation. The terminal in the inactive mode introduced in the next-generation mobile communication system performs a Logged MDT operation. When a specific terminal is in the connected mode, the network provides configuration information for performing the Logged MDT operation to the terminal, and after the terminal switches to the standby mode or inactive mode, the configured information is collected and stored. [Table 1] below shows the relationship between the MDT operation and the RRC state.

[Table 1]

1D is a diagram illustrating a method of collecting and reporting cell measurement information according to an embodiment of the present disclosure.

The terminal 1d-05 switches from the standby mode or the inactive mode (1d-10) to the connected mode (1d-15). In the connected mode (1d-15), MDT data is collected and reported to the base station through immediate MDT operation. The terminal 1d-05, which has been switched to the connected mode (1d-15), is provided with Logged MDT configuration information performed in the standby mode or the inactive mode from the base station (1d-20). The Logged MDT configuration information receives a predetermined RRC message and is transmitted to the terminal 1d-05, and the terminal 1d-05 receiving the predetermined RRC message drives a first timer (1d-55). The terminal 1d-05 performs the Logged MDT operation in the standby mode or the inactive mode (1d-10) period until the first timer expires. The value of the first timer is included in the Logged MDT configuration information. When the terminal 1d-05 switches to the standby mode or the inactive mode (1d-10), it performs Logged MDT according to the received Logged MDT configuration information (1d-25). The terminal 1d-05 stores predetermined information collected for each set period and logging interval 1d-35 (1d-30, 1d-45). Also, if valid location information (1d-40) has been collected, the collected information should also be stored. The validity of the location information is determined to be valid when a predetermined time (1d-50) has elapsed after the corresponding information is collected. This predetermined time is equal to or shorter than the logged interval (1d-35). Even before the first timer expires, the terminal 1d-05 temporarily suspends the Logged MDT operation being performed when switching to the connected mode 1d-15 (1d-60). However, the first timer does not stop even in the connected mode (1d-15) period, but continues to be driven. That is, the first timer continues to be driven regardless of a change in the radio connection state (RRC state). However, when the terminal memory for storing the MDT data is insufficient, when it cannot be stored anymore, or when the Logged MDT setting information is released, the first timer is stopped. The case in which the Logged MDT configuration information is released is when other Logged MDT configuration information is provided from the serving RAT or another RAT, or when the terminal 1d-05 is detached or the power is cut off. During the connection establishment process (RRC Connection Establishment) or the connection restart process (RRC Connection Resume), the terminal (1d-05) uses the RRC Setup Complete message or the RRC Resume Complete message to collect the collection stored by the terminal (1d-05) It reports to the base station that it has information (MDT data) (1d-65).

The connection establishment process (RRC Connection Establishment) is a process in which the terminal switches from the standby mode to the connected mode. The connection establishment process usually consists of three steps as follows, and three types of RRC messages are used.

- Step 1: The terminal transmits an RRC Setup Request message to the base station

- Step 2: The base station transmits the RRC Setup message to the terminal

- Step 3: The terminal transmits the RRC Setup Complete message to the base station

Here, the connection restart process is a process in which the terminal switches from the inactive mode to the connected mode. The connection restart process usually consists of three steps as follows, and three types of RRC messages are used.

- Step 1: The terminal transmits an RRC Resume Request message to the base station

- Step 2: The base station transmits an RRC Resume message to the terminal

- Step 3: UE transmits RRC Resume Complete message to base station

The terminal 1d-05 reports information indicating that it has collection information (MDT data) to the target base station during the RRC Connection Reestablishment and handover processes in addition to the connection establishment process or the connection restart process. If Logged MDT is set, but there is no collected and saved information yet, report is omitted. The base station receiving this report may request a report of the MDT data stored by the terminal 1d-05 if necessary. The unreported MDT data must be continuously stored by the terminal 1d-05 for a predetermined time. If the terminal 1d-05 is switched back to the standby mode or the inactive mode, and the first timer has not yet expired, the Logged MDT operation is restarted again (1d-70). If the first timer expires, the Logged MDT operation is stopped (1d-75). The terminal 1d-05, which has stopped the logged MDT operation, drives the second timer (1d-80), and maintains the stored MDT data until the second timer expires. After the second timer expires, whether to delete the MDT data being stored is determined by the terminal implementation. The value of the second timer is included in the Logged MDT setting information, or is not set and a predefined value is applied. When the terminal 1d-05 is switched back to the connected mode, it reports to the base station that it has the collection information (MDT data) it stores (1d-85). This time, the base station uses a predetermined RRC message to request a report of the MDT data stored by the terminal 1d-05 (1d-90). Accordingly, the terminal 1d-05 receives the MDT data being stored in a predetermined RRC message, and reports the RRC message to the base station (1d-95).

1E is a flowchart of an operation for collecting and reporting cell measurement information according to an embodiment of the present disclosure.

The terminal 1e-05 establishes a connection with the base station 1e-10 (1e-15). The terminal 1e-05 provides terminal capability information to the base station 1e-10 (1e-20), and may indicate whether it supports the MDT operation and what frequency it can measure. The base station 1e-10 receives the configuration information necessary to perform the Logged MDT operation in a predetermined RRC message and transmits it to the terminal 1e-05 (1e-25). In one embodiment, the configuration information required to perform the Logged MDT operation may include at least one of the following information.

- Trace Reference information

- Trace Recording Session Reference information

- TCE (Trace Collection Entity) ID information: The base station transmits the MDT data information reported from the terminal to the data server designated by the TCE ID.

- Absolute Time: Absolute time in the current cell that provides Logged MDT setting information.

- Area Configuration: Through the Logged MDT operation, the area information that can collect and store measurement information is indicated in units of cells. It may also include RAT information for which measurement information should be collected. The list included in the RAT information is a black list or a white list. If it is a black list, cell measurement information is collected for RATs not included in the list. If it is a white list, cell measurement information is not collected for RATs not included in the list.

- Logging Duration: As the value of the first timer, when the first timer is running, the Logged MDT operation is performed in the standby mode or the inactive mode.

- Logging Interval: It is the period to save the collected information.

- plmn-IdentityList (i.e. MDT PLMN list): PLMN list information, and stores PLMN information capable of not only performing a Logged MDT operation, but also reporting whether to store MDT data and report MDT data.

- An indicator indicating whether to perform Logged MDT operation in standby mode, inactive mode, or both. The RRC state for performing the Logged MDT operation may be indicated by the corresponding indicator, or it may be defined to always perform the Logged MDT operation in the standby mode and the inactive mode without the indicator. The UE performs the Logged MDT operation only in the RRC state indicated by the indicator.

- An indicator indicating whether to collect and store beam level measurement information. A beam antenna may be applied in a next-generation mobile communication system. Without a corresponding indicator, it can be defined that beam level measurement measurements are always collected and stored for a frequency at which a beam-based operation is performed.

- Information on the maximum number of beams to be collected or stored, and information about the minimum signal strength of the beam to be stored. The terminal omits the storage of information on a beam weaker than the minimum signal strength. If all beams are weaker than the set minimum signal value, the terminal may store one beam information having the strongest signal strength among them, or may include an indicator that all beams are weaker than the set minimum signal value.

- An indicator indicating whether the MDT retrieval operation can be triggered in the 2-step restart process (RRC Resume)

Upon receiving the Logged MDT configuration information, the terminal 1e-05 drives the first timer (1e-30). The value of the first timer may be set to be the same as the value of Logging Duration. The base station 1e-10 uses the RRC Release message to switch the terminal 1e-05 to the standby mode or the inactive mode (1e-35). Depending on which RRC state is converted, the RRC Release message contains configuration information for operation in the RRC state. If the first timer is running, the terminal 1e-05 performs Logged MDT in the standby mode or the inactive mode (1e-40). Signal strength of the serving cell and neighboring cells is measured, and location information is obtained. When the beam level measurement is set, a signal strength value for a beam greater than the set minimum value is collected and stored in the serving cell and the adjacent cell. The maximum number of beams that can be stored is set or predefined. Signal strength means RSRP or RSRQ or SINR. The collected information is saved every Logged Interval period. Each log information stored in each cycle includes an indicator indicating whether the stored information was collected in the standby mode or in the inactive mode. Alternatively, the indicator may be included in every first log in which the mode is switched. This can minimize signaling overhead due to the indicator. When the first timer expires (1e-45), the Logged MDT operation is stopped (1e-50).

If the terminal 1e-05 is in standby mode or inactive mode by the RRC Release message, receives RAN or CN paging from the base station 1e-10, or MO data transmission is activated, the terminal 1e- 05) initializes the establishment process or the resume process for switching from the standby mode or the inactive mode to the connected mode.

The establishment process or resume process can be configured as follows.

- Step 1: The UE transmits an RRC Setup Request message or RRC Resume Request message to the base station (1e-55)

- Step 2: BS transmits RRC Setup message or RRC Resume message to UE (1e-60)

- Step 3: UE transmits RRC Setup Complete message or RRC Resume Complete message to the base station (1e-65)

The terminal 1e-05 receives an indicator indicating whether there is MDT data stored therein in the RRC Setup Complete or RRC Resume Complete message. Upon receiving the RRC Setup Complete message, the base station 1e-10 requests a report of the MDT data by using a predetermined RRC message, if necessary (1e-70). Upon receiving this request, the terminal 1e-05 reports MDT data using a predetermined RRC message (1e-75).

1F is a diagram for explaining a cell ID in a next-generation mobile communication system according to an embodiment of the present disclosure.

The cell ID used in the LTE system, Evolved Cell Global Identifier (ECGI), is unique regardless of the operator. However, the NCGI (New Radio Cell Global Identifier) in the next-generation mobile communication system may be different for each operator. In one embodiment, the NCGI may be composed of bits (1f-05) indicating the PLMN, bits indicating the gNB (1f-10), and other bits (1f-15). In this case, the bits indicating the gNB and other bits are referred to as NCI (New Radio Cell Identity), and in general NR RRC, NCI is provided as cellIdentity IE. In the MDT operation, ID information of cells measured by the terminal is stored, and the information stored in the connected mode is reported to the base station. Although the UE stores one ECGI value as ID information for an LTE cell, a method for efficiently storing and reporting the multiple cell IDs exists for an NR cell is required. For example, in LTE MDT, the terminal stores the following information through the MDT operation. The stored information is reported to the base station through the UEInformationResponse message. In the following stored information, the servCellIdentity field indicates ID information, ECGI, of an LTE serving cell.

The NR base station stores the ID information of the NR cell in the following PLMN-IdentityInfoList IE of SIB1 and provides it to the terminal. One operator may provide a cellIdentity field corresponding to each PLMN together with a plurality of PLMNs. The combination of the NCI value indicated by the PLMN and the corresponding cellIdentity is the NCGI. Accordingly, there may be several NCGIs indicating one cell. The reason why the NR system was developed so that each operator can have a plurality of cell IDs is to efficiently operate cells when sharing networks between operators.

1G is a flowchart of a terminal for storing cell ID information in the present invention.

In step 1g-05, the terminal collects cell ID information from system information broadcast by the base station.

In step 1g-10, the UE determines the purpose of collecting cell ID information.

If the purpose of collecting cell ID information in step 1g-15 is Automatic Neighbor Relation (ANR), the UE reports all PLMN information and cell information collected in the connected mode to the serving base station.

If the purpose of collecting cell ID information in step 1g-20 is MDT, the UE stores specific PLMN information and cell information when in standby mode or inactive mode.

In step 1g-25, the UE reports specific PLMN information and cell information when in standby mode or inactive mode.

In one embodiment, predetermined specific PLMN and cell information in steps 1g-20 and 1g-25 may be determined as follows.

Option 1: Store or report one NCGI information.

Option 1-1: PLMN-IdentityInfoList Stores or reports the first PLMN-Identity stored in the first PLMN-IdentityInfo in the IE and the cellIdentity value stored in the first PLMN-IdentityInfo. In general, the first PLMN-IdentityInfo in the PLMN-IdentityInfoList IE is a business operator that operates the corresponding base station, and thus contains cell information used by the operator.

Option 1-2: If there is a match among the RPLMNs or equivalent PLMNs among the PLMNs supported by the serving cell, the cellIdentity value stored in the PLMN-IdentityInfo belonging to the matching RPLMN and the RPLMN is stored or reported.

Option 1-3: Stores or reports the PLMN belonging to the MDT PLMN list among the PLMNs supported by the serving cell and the cellIdentity value stored in the PLMN-IdentityInfo belonging to the corresponding PLMN. If a plurality of PLMNs among the PLMNs supported by the serving cell belong to the MDT PLMN list, one PLMN is selected from the MDT PLMN list. For example, it is possible to select the earliest PLMN or PLMN matching the RPLMN in the order received in the MDT PLMN list.

Option 2: Store or report multiple NCGI information.

Option 2-1: PLMN-IdentityInfoList Stores or reports the first PLMN-Identity stored in each PLMN-IdentityInfo and the cellIdentity value stored in each PLMN-IdentityInfo in the IE. Accordingly, there are as many combinations of PLMN-Identity and cellIdentity as the number of PLMN-IdentityInfo.

Option 4: PLMN-IdentityInfoList Stores or reports all PLMN-Identities stored in each PLMN-IdentityInfo and cellIdentity values stored in each PLMN-IdentityInfo in the IE. Accordingly, a combination of one or more PLMN-Identity and cellIdentity exists as many as the number of PLMN-IdentityInfo.

Option 5: PLMN-Identity indicating the PLMN belonging to the MDT PLMN list and the cellIdentity value stored in the PLMN-IdentityInfo to which the PLMN-Identity belongs are stored or reported.

The method of storing NCGI information may be applied to storing cell ID information in accessibility measurement, RLF report, and RACH report in addition to logged MDT.

1H is a flowchart of a terminal storing PLMN information according to an embodiment of the present disclosure.

Accessibility measurement is a technique for storing terminal measurement information at the time of failure when the establishment or resume process performed by the terminal to switch from the standby mode or inactive mode to the connected mode fails, and reporting it when the terminal switches to the connected mode later to be. For establishment, when the UE triggers the RRCSetupRequest message, the UE drives the T300 timer. If the terminal does not receive the RRCSetup message from the base station until the T300 timer expires, it is considered that the establishment process has failed. For resume, when the UE triggers the RRCResumeRequest message, the UE drives the T319 timer. If the terminal does not receive the RRCResume message from the base station until the T319 timer expires, it is considered that the resume process has failed.

The establishment process may not have an RPLMN because it can be performed at the initial access of the terminal. Therefore, the terminal stores the selected PLMN when establishment failure occurs. Thereafter, after switching to the connected mode in one serving cell, if the current RPLMN matches the stored selected PLMN, an indicator indicating that there is stored information in an establishment failure is reported to the serving cell. In contrast, the terminal in the inactive mode has an RPLMN because it has connected to the base station at least once. Therefore, the terminal stores the RPLMN when resume failure occurs. Thereafter, after being switched to the connected mode in one serving cell, if the current RPLMN matches the stored RPLMN, an indicator indicating that there is stored information upon resume failure is reported to the serving cell.

In step 1h-05, the terminal determines whether the T300 or T319 timer has expired.

If the T300 timer expires in step 1h-10, the terminal considers it an establishment failure and deletes the information stored in the VarConnEstFailReport IE.

In step 1h-15, the terminal stores the selected PLMN selected by the terminal NAS among the PLMNs included in the plmn-IdentityList of SIB1 broadcast by the cell that has performed the establishment process in the VarConnEstFailReport IE.

If the T319 timer expires in step 1h-20, the UE regards it as resume failure and deletes the information stored in the VarConnEstFailReport IE.

In step 1h-25, the UE stores the RPLMN in the VarConnEstFailReport IE.

1I is a flowchart of a terminal for storing information on the number of establishment failures according to an embodiment of the present disclosure.

The number of connection setup attempts that occurred after RLF (LTE Radio Link Failure) is useful information for network optimization. RLF can occur for a number of reasons.

The physical layer of the terminal measures the downlink signal quality from the CRS of the serving cell. Then, it is determined whether the signal quality is lower than a certain threshold Qout. Here, the threshold value is a signal quality value corresponding to a specific BLER (Block Error Ratio) measured in a Physical Downlink Control Channel (PDCCH). If the signal quality is lower than the specific threshold Qout, the physical layer transmits an 'out-of-sync' indicator to the upper layer. This operation is called RLM (Radio Link Monitoring). If the 'out-of-sync' indicator is delivered to the upper layer more than a specific number of times, the upper layer drives a specific timer, and when the timer expires, RLF is declared.

As previously explained, RLFs can be declared according to the results from the RLM. The physical layer of the UE determines whether the downlink signal quality is lower than a specific threshold Qout from a CRS (Cell Specific Reference Signal) of the serving cell at every specific period, Qout evaluation period. If the signal quality is lower than the specific threshold Qout, the physical layer transmits an 'out-of-sync' indicator to the upper layer. After the minimum indicator is transmitted to the upper layer, when the specific number of times N310 is transmitted to the upper layer, a specific timer T310 is driven. The physical layer also determines whether the downlink signal quality is higher than a specific threshold Qin from the CRS of the serving cell. If the signal quality is higher than the specific threshold Qin, the physical layer transmits the 'in-sync' indicator to the upper layer. When the 'in-sync' indicator is delivered to the upper layer a certain number of times, the running T310 timer is stopped. If the T310 timer is not stopped and expires, the upper layer declares an RLF. After RLF declaration, the UE drives another T311 timer. The terminal searches for a new suitable cell, and if it does not find a new suitable cell until the T311 timer expires, it switches to the standby mode. If a new suitable cell is found before the T311 timer expires, the UE drives the T301 timer and performs a re-establishment process with the new suitable cell. If the re-establishment is not successfully completed before the T301 timer expires, the UE switches to the standby mode. If the re-establishment is successful, the terminal continues the connected mode in the cell. RLF may be declared by an RLM operation, and may be declared according to another condition. RLF may be declared even when random access fails. In addition, even if the maximum number of retransmissions in the RLC layer is reached or the packet is not successfully delivered, RLF is declared.

Another case in which RLF is declared is when handover fails. Upon receiving the RRCConnectionReconfiguration message including the handover configuration information and the mobilityControlInfo IE, the UE drives the T304 timer. The timer value of T304 is provided in mobilityControlInfo. If the random access with the target cell is not successfully completed before the T304 timer expires, the UE regards it as a handover failure and declares an RLF.

The present disclosure describes a process of storing the number of consecutive failed connection setup attempts per cell after RLF generation and reporting this through an establishment failure reporting (accessibility measurement reporting) process. After the RLF occurs, the UE may attempt to setup one or more cells. At this time, the number of consecutive failed setup attempts is stored separately for each cell in which setup is attempted, or the number of failed setup attempts that have occurred continuously is stored, or the number of failed attempts in the cell where the most consecutive failed setup attempts occurred The number of times can be saved.

In step 1i-05, the UE undergoes continuous establishment failure in the first cell.

In step 1i-10, the terminal counts and stores the number of successive setup attempts failure in the first cell.

In step 1i-15, the UE moves to the second cell.

In step 1i-20, the UE undergoes continuous establishment failure in the second cell.

In step 1i-25, the terminal counts and stores the number of successive setup attempts failure in the second cell.

In step 1i-30, the UE moves back to the first cell.

In step 1i-35, the UE undergoes continuous establishment failure in the first cell.

In step 1i-40, the terminal counts and stores the number of successive setup attempts failure in the first cell.

In step 1i-45, the UE succeeds in the establishment process in the first cell and is switched to the connected mode.

In step 1i-50, the terminal reports the stored information on the number of consecutive connection attempt failures to the cell. At this time,

- Report information on the number of consecutive failures in the first cell, information on the number of consecutive failures in the second cell, and information on the number of consecutive failures in the second first cell (total 3 sets)

- Report information on the number of consecutive failures in the second first cell that was attempted last; or

- Report the number of failed attempts in the cell where the most consecutive failed setup attempts occurred.

If only the most recent consecutive failed setup attempts are reported, the terminal deletes previously stored information on the number of consecutive failed attempts and stores only the most recent information.

1J is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present disclosure.

Referring to FIG. 1J , the terminal includes a radio frequency (RF) processing unit 1j-10, a baseband processing unit 1j-20, a storage unit 1j-30, and a control unit 1j-40.

The RF processing unit 1j-10 performs a function for transmitting and receiving a signal through a wireless channel, such as band conversion and amplification of the signal. That is, the RF processing unit 1j-10 up-converts the baseband signal provided from the baseband processing unit 1j-20 into an RF band signal, transmits it through the antenna, and converts the RF band signal received through the antenna to the baseband. down-convert to a signal. For example, the RF processing unit 1j-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog to digital converter (ADC), and the like. have. In FIG. 1J , only one antenna is shown, but the terminal may have multiple antennas. Also, the RF processing unit 1j-10 may include a plurality of RF chains. Furthermore, the RF processing unit 1j-10 may perform beamforming. For beamforming, the RF processing unit 1j-10 may adjust the phase and magnitude of each of signals transmitted and received through a plurality of antennas or antenna elements. In addition, the RF processing unit may perform MIMO, and may receive multiple layers when performing the MIMO operation.

The baseband processing unit 1j-20 performs a function of converting between the baseband signal and the bit stream according to the physical layer standard of the system. For example, when transmitting data, the baseband processing unit 1j-20 generates complex symbols by encoding and modulating the transmitted bit stream. Also, upon data reception, the baseband processing unit 1j-20 restores the received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit 1j-10. For example, in the case of orthogonal frequency division multiplexing (OFDM), when transmitting data, the baseband processing unit 1j-20 encodes and modulates a transmission bit stream to generate complex symbols, and maps the complex symbols to subcarriers. After that, OFDM symbols are constructed through inverse fast Fourier transform (IFFT) operation and cyclic prefix (CP) insertion. In addition, upon data reception, the baseband processing unit 1j-20 divides the baseband signal provided from the RF processing unit 1j-10 into OFDM symbol units, and is mapped to subcarriers through a fast Fourier transform (FFT) operation. After restoring the signals, the received bit stream is restored through demodulation and decoding.

The baseband processing unit 1j-20 and the RF processing unit 1j-10 transmit and receive signals as described above. Accordingly, the baseband processing unit 1j-20 and the RF processing unit 1j-10 may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit 1j-20 and the RF processing unit 1j-10 may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit 1j-20 and the RF processing unit 1j-10 may include different communication modules to process signals of different frequency bands. For example, different wireless access technologies may include a wireless LAN (eg, IEEE 802.11), a cellular network (eg, LTE), and the like. In addition, the different frequency bands may include a super high frequency (SHF) (eg, 2.NRHz, NRhz) band and a millimeter wave (eg, 60GHz) band.

The storage unit 1j-30 stores data such as a basic program, an application program, and setting information for the operation of the terminal. In particular, the storage unit 1j-30 may store information related to a second access node that performs wireless communication using a second wireless access technology. In addition, the storage unit 1j-30 provides stored data according to the request of the control unit 1j-40.

The controller 1j-40 controls overall operations of the terminal. For example, the control unit 1j-40 transmits and receives signals through the baseband processing unit 1j-20 and the RF processing unit 1j-10. Also, the control unit 1j-40 writes and reads data in the storage unit 1j-40. To this end, the controller 1j-40 may include at least one processor. For example, the controller 1j-40 may include a communication processor (CP) that controls for communication and an application processor (AP) that controls an upper layer such as an application program.

1K is a block diagram illustrating a configuration of a base station according to an embodiment of the present disclosure.

As shown in FIG. 1K, the base station includes an RF processing unit 1k-10, a baseband processing unit 1k-20, a backhaul communication unit 1k-30, a storage unit 1k-40, and a control unit 1k-50. consists of including

The RF processing unit 1k-10 performs a function for transmitting and receiving a signal through a wireless channel, such as band conversion and amplification of the signal. That is, the RF processing unit 1k-10 up-converts the baseband signal provided from the baseband processing unit 1k-20 into an RF band signal, transmits it through the antenna, and converts the RF band signal received through the antenna to the baseband. downconverted to a signal. For example, the RF processing unit 1k-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like. In the drawing, only one antenna is shown, but the first access node may include a plurality of antennas. Also, the RF processing unit 1k-10 may include a plurality of RF chains. Furthermore, the RF processing unit 1k-10 may perform beamforming. For beamforming, the RF processing unit 1k-10 may adjust the phase and magnitude of each of the signals transmitted and received through a plurality of antennas or antenna elements. The RF processing unit may perform a downlink MIMO operation by transmitting one or more layers.

The baseband processing unit 1k-20 performs a function of converting a baseband signal and a bit stream according to the physical layer standard of the first radio access technology. For example, when transmitting data, the baseband processing unit 1k-20 generates complex symbols by encoding and modulating the transmitted bit stream. Also, upon data reception, the baseband processing unit 1k-20 restores the received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit 1k-10. For example, in the OFDM scheme, when data is transmitted, the baseband processing unit 1k-20 generates complex symbols by encoding and modulating the transmitted bit stream, maps the complex symbols to subcarriers, and performs IFFT operation and OFDM symbols are configured through CP insertion. Also, upon data reception, the baseband processing unit 1k-20 divides the baseband signal provided from the RF processing unit 1k-10 into OFDM symbol units, and restores signals mapped to subcarriers through FFT operation. , recovers the received bit stream through demodulation and decoding. The baseband processing unit 1k-20 and the RF processing unit 1k-10 transmit and receive signals as described above. Accordingly, the baseband processing unit 1k-20 and the RF processing unit 1k-10 may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

The backhaul communication unit 1k-30 provides an interface for performing communication with other nodes in the network. That is, the backhaul communication unit 1k-30 converts a bit string transmitted from a main station to another node, for example, an auxiliary base station, a core network, etc. into a physical signal, and converts a physical signal received from another node into a bit string do.

The storage unit 1k-40 stores data such as a basic program, an application program, and setting information for the operation of the base station. In particular, the storage unit 1k-40 may store information on a bearer allocated to an accessed terminal, a measurement result reported from the accessed terminal, and the like. In addition, the storage unit 1k-40 may store information serving as a criterion for determining whether to provide or stop multiple connections to the terminal. In addition, the storage unit 1k-40 provides the stored data according to the request of the control unit 1k-50.

The control unit 1k-50 controls overall operations of the main station. For example, the control unit 1k-50 transmits and receives signals through the baseband processing unit 1k-20 and the RF processing unit 1k-10 or through the backhaul communication unit 1k-30. In addition, the control unit 1k-50 writes and reads data in the storage unit 1k-40. To this end, the controller 1k-50 may include at least one processor.

Methods according to the embodiments described in the claims or specifications of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium are configured to be executable by one or more processors in an electronic device (device). One or more programs include instructions for causing an electronic device to execute methods according to embodiments described in a claim or specification of the present disclosure.

Such programs (software modules, software) include random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable ROM (EEPROM: Electrically Erasable Programmable Read Only Memory), magnetic disc storage device, Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs), or any other form of It may be stored in an optical storage device or a magnetic cassette. Alternatively, it may be stored in a memory composed of a combination of some or all thereof. In addition, each configuration memory may be included in plurality.

In addition, the program accesses through a communication network composed of a communication network such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. It may be stored in an attachable storage device that can be accessed. Such a storage device may be connected to a device implementing an embodiment of the present disclosure through an external port. In addition, a separate storage device on the communication network may be connected to the device implementing the embodiment of the present disclosure.

In the specific embodiments of the present disclosure described above, elements included in the invention are expressed in the singular or plural according to the specific embodiments presented. However, the singular or plural expression is appropriately selected for the context presented for convenience of description, and the present disclosure is not limited to the singular or plural component, and even if the component is expressed in plural, it is composed of a singular or singular. Even an expressed component may be composed of a plurality of components.

On the other hand, the embodiments of the present disclosure disclosed in the present specification and drawings are merely presented as specific examples to easily explain the technical content of the present disclosure and help the understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it is apparent to those of ordinary skill in the art to which other modifications are possible based on the technical spirit of the present disclosure. In addition, each of the above embodiments may be operated in combination with each other as needed. For example, the base station and the terminal may be operated by combining parts of one embodiment and another embodiment of the present disclosure. In addition, other modifications based on the technical idea of the above embodiments may be implemented in various systems such as FDD LTE system, TDD LTE system, 5G or NR system.

Claims (1)

A method of operating a terminal in a wireless communication system, the method comprising:
Counting and storing the number of consecutive first connection establishment failure attempts in the first cell;
after moving from the first cell to the second cell, counting and storing the number of consecutive second connection establishment failure attempts in the second cell;
after moving from the second cell to the first cell, counting and storing the number of consecutive third connection establishment failure attempts in the first cell; and
After being established with the first cell, at least one of the stored number of consecutive failed attempts to establish a first connection, the number of consecutive failed attempts to establish a second connection, or the number of consecutive failed attempts to establish a third connection. A method comprising the step of reporting the abnormality to the base station.

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