KR102272363B1 - Method and apparatus for cell reselection in wireless communication - Google Patents

Abstract

Various embodiments of the present invention relate to a method and apparatus for cell reselection in a wireless communication system, and the method for cell reselection of a terminal is associated with a network selection mode and a PLMN different from a registered Public Land Mobile Network (PLMN). checking whether at least one Closed Subscriber Group (CSG) is identified; When the network selection mode is a manual PLMN selection mode and at least one CSG associated with a PLMN different from the registered PLMN is identified, controlling an autonomous search function (ASF) not to operate. Various other embodiments are also possible.

Description

Method and apparatus for cell reselection in a wireless communication system {METHOD AND APPARATUS FOR CELL RESELECTION IN WIRELESS COMMUNICATION}

The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for cell reselection in a wireless communication system.

The long term evolution (LTE) system standardized by the 3rd Generation Partnership Project (3GPP) group uses orthogonal frequency division multiple access (OFDMA) in the downlink and single carrier frequency division multiple access (SC-FDMA) in the uplink. do. Multiple input multiple output (MIMO) with up to 4 antennas is recommended. Recently, 3GPP LTE-A (LTE-Advanced), an evolution of 3GPP LTE, is being discussed.

In LTE systems, we are introducing Closed Subscriber Group (CSG) operated by HeNB (or Home eNode B). The CSG cell refers to a cell that can be used only by one or more specific users or terminals, and is used for the purpose of expanding a service coverage for a user or increasing a radio capacity. As an example in which the CSG cell is used, the case of Home Node B, which can be installed and used by a user at the same place as home, may be regarded as an example of the CSG cell. The CSG cell has a narrower coverage than the cell served by the eNode B. In addition, the CSG cell may be used as a femto cell or a pico cell, which are general terms in wireless communication. In other words, a femto cell in wireless communication may be applied as a term CSG cell in LTE. Hereinafter, a cell operated by the eNode B is abbreviated as a normal cell or a macro cell to distinguish it from a CSG cell.

Section 5.2.4.8 of 3GPP TS 36.304 V11.5.0 (2013-09) defines the behavior for cell-reselection (cell reselection, the process of changing a serviced cell by camping on from a serving cell to a neighboring cell).

For example, clause 5.2.4.8.1 states that "in addition to normal cell reselection, when at least one CSG ID related to Public Land Mobile Network (PLMN) identity is included in the CSG whitelist of the UE, the UE includes inter-RAT frequencies. will use an automatic search function (ASF) to detect at least previously visited CSG member cells on non-serving frequencies. The UE will also use automatic search for serving frequencies. If the UE's CSG whitelist is If empty, the UE may disable the automatic discovery function for CSG cells."

In the automatic search function, when the terminal has a CSG whitelist (or allowed CSG list), the terminal searches for a cell of the CSG whitelist or allowed CSG list at a specific period or time depending on implementation, and serves in a CSG cell accessible to the terminal It means the ability to receive.

The CSG whitelist is defined as "A list provided by NAS containing all the CSG identities and their associated PLMN IDs of the CSGs to which the subscriber belongs." in 3GPP TS 36.304, and the CSG identity is "An identifier broadcast by a CSG or hybrid cell/cells and used by the UE to facilitate access for authorized members of the associated Closed Subscriber Group”, and CSG member cell is “a cell broadcasting the identity of the selected PLMN, registered PLMN or equivalent PLMN and for which the CSG whitelist of the UE includes an entry comprising cell's CSG ID and the respective PLMN identity".

Also, in 3.2.2.2 of 3GPP TS 22.011 V12.0.0 (2013-03) and 3GPP TS 23.122 V12.2.0 (2013-09), it is explained that the UE will not attempt to register with a PLMN not selected by the user. .

For example, once a UE is registered with a PLMN selected by a user, the UE will not automatically register with another PLMN unless in the following two circumstances.

1. When a new PLMN is declared as a PLMN equivalent to a registered PLMN

2. When the user selects automatic mode

According to the manual PLMN (Public Land Mobile Network) selection rule according to 3GPP TS 22.011, the rule "the UE does not attempt to register with a PLMN not selected by the user" may be violated.

For example, if the UE in the manual PLMN selection mode is registered with the first PLMN, and the UE detects a PLMN other than the first PLMN (eg, a CSG related to the second PLMN) and starts the automatic discovery function, Another PLMN (eg, CSG of the second PLMN) may be selected.

However, this may violate the manual PLMN selection rule according to 3GPP TS 22.011, which states that the UE does not attempt to register with another PLMN unless it is changed to an automatic mode, is equivalent to the PLMN registered by the PLMN, or the user has not selected a different PLMN.

In addition, the vicinity of the CSG cell belonging to the second PLMN is very narrow, and the availability of the second PLMN macro cell may or may not provide a general service to the UE, so the recovery attempt of the second PLMN is general to the user. There may be delays in the provision of services.

For example, when the UE is registered with the first PLMN in the automatic PLMN selection mode (the whitelist of the UE includes entries (CSGs) belonging to the first PLMN and the second PLMN), the UE uses another PLMN instead of the first PLMN. By detecting a CSG cell belonging to a PLMN (eg, a CSG of the second PLMN), an automatic search function may be started to select another PLMN. Then, when the UE moves out of the CSG coverage area, the UE will perform a recovery procedure to the RPLMN based on the second PLMN.

Accordingly, various embodiments of the present invention may provide a method and apparatus for cell reselection in a wireless communication system.

Various embodiments of the present invention may provide a method and apparatus for not attempting to register with another PLMN when a terminal in the manual PLMN selection mode is registered with the corresponding PLMN in a wireless communication system.

Various embodiments of the present invention may provide a method and apparatus for preventing a recovery procedure from being delayed when leaving a CSG cell in a wireless communication system.

According to various embodiments of the present disclosure, in a method for cell reselection of a terminal, at least one Closed Subscriber Group (CSG) associated with a PLMN different from a network selection mode and a registered Public Land Mobile Network (PLMN) is identified. to confirm; When the network selection mode is a manual PLMN selection mode and at least one CSG associated with a PLMN different from the registered PLMN is identified, controlling an autonomous search function (ASF) not to operate.

According to various embodiments, the step of controlling the automatic search function not to operate may include modifying the CSG whitelist so that only the registered PLMN and its equivalent PLMN are included.

According to various embodiments, when the network selection mode is changed to an automatic PLMN selection mode, the method may include restoring the CSG whitelist.

According to various embodiments, the step of controlling the automatic search function not to operate may include determining whether to trigger the automatic search function before triggering the automatic search function.

According to various embodiments, the method may further include controlling the automatic search function to operate when the network selection mode is an automatic PLMN selection mode or a CSG associated with a PLMN different from the registered PLMN is not identified. have.

According to various embodiments, the method may further include, when the network selection mode is an automatic PLMN selection mode, performing the automatic search function to select a CSG cell associated with another PLMN; The method may further include storing information on the registered PLMN before registration to the CSG cell associated with the other PLMN starts. The method may further include the step of restoring to the registered PLMN by using the stored information on the registered PLMN according to a predefined procedure when registration to the CSG cell associated with the other PLMN fails. In addition, after successful registration to the CSG cell associated with the other PLMN, when the registration is out of the service area of the successful CSG cell, the method may include re-searching to the CSG cell in which the registration was successful.

According to various embodiments, the step of re-searching to the CSG cell in which the registration is successful may include: checking the priority of available PLMNs; It may include searching for PLMNs according to priority.

According to various embodiments, when at least one CSG ID related to PLMN identity is included in the CSG whitelist, the automatic search function may be performed to detect previously visited CSG member cells.

According to various embodiments of the present disclosure, in an apparatus for cell reselection of a terminal, at least one Closed Subscriber Group (CSG) associated with a network selection mode and a PLMN different from a registered Public Land Mobile Network (PLMN) is identified. and a control unit for controlling not to operate an automatic search function (ASF) when the network selection mode is a manual PLMN selection mode and at least one CSG associated with a PLMN different from the registered PLMN is identified can do.

According to various embodiments, in order to control the automatic search function not to operate, the controller may modify the CSG whitelist to include only the registered PLMN and its equivalent PLMN.

According to various embodiments, the controller may restore the CSG whitelist when the network selection mode is changed to an automatic PLMN selection mode.

According to various embodiments, in order to control the automatic search function not to operate, the controller may determine whether to trigger the automatic search function before triggering the automatic search function.

According to various embodiments, the controller may control the automatic search function to operate when the network selection mode is an automatic PLMN selection mode or a CSG associated with a PLMN different from the registered PLMN is not identified.

According to various embodiments, when the network selection mode is the automatic PLMN selection mode, the control unit selects a CSG cell associated with another PLMN by performing the automatic search function, and registration starts with the CSG cell associated with the other PLMN. Before it is done, information on the registered PLMN may be stored.

According to various embodiments, when registration to the CSG cell associated with the other PLMN fails, the controller may restore the registered PLMN to the registered PLMN by using the stored information on the registered PLMN according to a predefined procedure.

According to various embodiments, the controller may, after successful registration to the CSG cell associated with the other PLMN, attempt to search again to the CSG cell in which the registration has been successful, when out of the service area of the CSG cell in which the registration has been successful.

According to various embodiments, the controller may check the priorities of available PLMNs and search for the PLMNs according to the priorities in order to attempt a search again to the CSG cell in which the registration has been successful.

According to various embodiments, when at least one CSG ID related to PLMN identity is included in the CSG whitelist, the automatic search function may be performed to detect previously visited CSG member cells.

As described above, when the terminal in the manual PLMN (Public Land Mobile Network) selection mode is registered with the corresponding PLMN and CSGs related to other PLMNs are included in the CSG finger print information, the PLMN currently registered in the CSG whitelist And by limiting to include only PLMNs equivalent thereto or disabling the automatic search function, it can be suggested that the terminal not attempt to register with another PLMN.

In addition, when the CSG associated with the first PLMN and the second PLMN is identified, after storing information on the first PLMN, when the terminal leaves the CSG service area associated with the second PLMN, the priority of the first PLMN By comparing the priority and the priority of the second PLMN, a recovery procedure is performed based on the first PLMN or the second PLMN, and when registration to the first PLMN or the second PLMN fails, the pre-stored first PLMN The delay in the recovery procedure can be minimized by performing a predefined recovery procedure based on the information on

1 illustrates a wireless communication system according to various embodiments of the present invention.
2 is a block diagram illustrating a radio protocol structure for a user plane according to various embodiments of the present invention.
3 is a block diagram illustrating a radio protocol structure for a control plane according to various embodiments of the present invention.
4 illustrates a method for cell reselection in a manual PLMN selection mode according to various embodiments of the present invention.
4 illustrates a method for cell reselection in a manual PLMN selection mode according to various embodiments of the present invention.
5 illustrates a method for cell reselection in a manual PLMN selection mode according to various embodiments of the present invention.
6 illustrates a method for preventing a recovery procedure from being delayed when leaving a CSG cell in an automatic PLMN selection mode according to various embodiments of the present invention.
7 is a flowchart for cell reselection in the manual PLMN selection mode according to various embodiments of the present invention.
8 is a flowchart for cell reselection in the manual PLMN selection mode according to various embodiments of the present invention.
9 is a flowchart for cell reselection in the manual PLMN selection mode according to various embodiments of the present invention.
10 is a flowchart for preventing the recovery procedure from being delayed when leaving the CSG cell in the automatic PLMN selection mode according to various embodiments of the present invention.
11 shows a flowchart for a recovery algorithm according to various embodiments of the present invention.
12 is a functional block diagram of a terminal according to various embodiments of the present invention.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. And, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present invention, 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, various embodiments of the present invention will be described with respect to a method and apparatus for cell reselection in a wireless communication system.

1 illustrates a wireless communication system according to various embodiments of the present invention. This may also be called an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN), or a Long Term Evolution (LTE)/LTE-A system.

The E-UTRAN includes a base station (BS) 20 that provides a control plane and a user plane to a user equipment (UE) (not shown). A terminal may be fixed or mobile, and may be referred to 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 that communicates with the terminal, and may be called by other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), and an access point.

The base stations 20 may be connected to each other through an X2 interface. The base station 20 is connected to an Evolved Packet Core (EPC) 30 through an S1 interface, more specifically, a Mobility Management Entity (MME) through S1-MME and a Serving Gateway (SGW) through S1-U.

The EPC 30 is composed of an MME, an S-GW and a Packet Data Network-Gateway (P-GW). The MME has access information of the terminal or information about the capability of the terminal, and this information is mainly used for mobility management of the terminal. The S-GW is a gateway having E-UTRAN as an endpoint, and the P-GW is a gateway having a PDN as an endpoint.

The layers of the Radio Interface Protocol between the terminal and the network are based on the lower three layers of the Open System Interconnection (OSI) standard model, which is widely known in communication systems, L1 (Layer 1), It can be divided into L2 (second layer) and L3 (third layer), of which the physical layer belonging to the first layer provides an information transfer service using a physical channel, The RRC (Radio Resource Control) layer located in the third layer performs a role of controlling radio resources between the terminal and the network. To this end, the RRC layer exchanges RRC messages between the terminal and the base station.

Meanwhile, a base station providing a CSG service is called a Home NodeB (HNB) or a Home eNodeB (HeNB) in 3GPP. Hereinafter, both HNB and HeNB are collectively referred to as HNB. The HNB 10 basically aims to provide a specialized service only to members belonging to the CSG. However, the service may be provided to users other than the CSG according to the operation mode setting of the HNB.

First, the HNBs 10 are connected to the EPC through the HNB GW or are directly connected to the EPC. Here, the HNB GW may look like a general BS to the MME. Also, the HNB GW may look like the MME to the HNB. Accordingly, the HNB and the HNB GW are connected through the S1 interface, and the HNB GW and the EPC are also connected through the S1 interface. In addition, even when the HNB and the EPC are directly connected, they are connected through the S1 interface. The function of HNB is mostly the same as that of general BS.

In general, HNB has low radio transmission power compared to BS owned by a mobile communication network operator. Accordingly, the service area provided by the HNB is generally smaller than the service area provided by the BS. Because of these characteristics, from a service area point of view, a cell provided by the HNB is often classified as a femto cell compared to a macro cell provided by the BS. In terms of the service provided, when the HNB provides a service only to a CSG group, the cell provided by the HNB is referred to as a CSG cell. Each CSG has a unique identifier, and this identifier is called a CSG identity (CSG identity). The terminal may have a list of CSGs to which it belongs as a member, and this CSG list may be changed by a request of the terminal or a command of the network. The terminal has a list of CSGs to which it is registered as a member, which is called a CSG white list.

The HNB transmits the CSG ID of the CSG it supports through system information so that only member terminals of the CSG are connected. When the UE discovers the CSG cell, it can check which CSG the CSG cell supports by reading the CSG ID included in the system information. The UE that reads the CSG ID considers the cell as an accessible cell only when it is a member of the corresponding CSG cell, that is, when the CSG corresponding to the CSG ID is included in its CSG whitelist.

It is not always necessary to allow access to the CSG terminal just because it is an HNB. According to the configuration setting of the HNB, it is possible to allow access of terminals other than CSG members. Which terminal is allowed to access is changed according to the configuration setting of the HNB, where the configuration setting refers to the setting of the HNB's access mode (also referred to as an operation mode). The access mode of the HNB is divided into the following three types according to which terminal a service is provided.

1) Closed access mode: A mode that provides services only to specific CSG members. The HNB provides the CSG cell.

2) Open access mode: A mode that provides services without the restriction of a specific CSG member like a general BS.

The HNB provides a normal cell, not a CSG cell. For convenience of description, a macro cell is generally defined to mean a cell operated in an open access mode.

3) Hybrid mode: A mode in which a CSG service can be provided to a specific CSG member and a service is also provided to a non-CSG member like a normal cell. A CSG member UE is recognized as a CSG cell, and a non-CSG member UE is recognized as a normal cell. Such a cell is called a hybrid cell.

The HNB informs the UE whether the cell it serves is a normal cell, which is a CSG cell, so that the UE knows whether or not the UE can access the cell. The HNB operating in the closed connection mode broadcasts that it is a CSG cell through system information. The HNB operating in the open connection mode broadcasts that it is not a CSG cell through system information. In this way, the HNB may include a CSG indicator indicating whether the cell it serves is a CSG cell in the system information.

In various embodiments of the present invention, the CSG whitelist of the terminal may be modified based on the PLMN selection mode. When the UE operates in the MANUAL PLMN selection mode, the UE may limit the CSG whitelist to include only the PLMNs currently registered and PLMNs equivalent thereto. If the user changes to the automatic PLMN selection mode, selects another PLMN, or the list of PLMNs equivalent to the currently registered PLMN is changed, the CSG whitelist may be updated again. In automatic PLMN selection mode, there is no restriction on CSG whitelist update, and all entries in allowed CSG list and operator CSG list can be updated according to TS 23.122. This solution will be illustrated in Figure 4 below.

In various embodiments of the present invention, when a finger printed CSG belonging to another PLMN is identified, the UE cannot immediately perform a PLMN search by itself. This may be determined in consideration of the current operation mode. For example, when the terminal is in the manual PLMN selection mode and the detected finger printed CSG is the CSG of other PLMNs as well as the current registered PLMN or its equivalent PLMN, the terminal does not allow an automatic search function (ASF). Accordingly, the UE does not select a finger printed CSG cell of another PLMN. This solution will be illustrated in Figure 5 below. The finger printed CSG means a CSG detected at the current location of the terminal.

Meanwhile, a service area of a CSG cell belonging to another PLMN is very small, and a normal service may or may not be provided to the terminal through a macro cell of the other PLMN. Therefore, the attempt to recover the other PLMN may be delayed in providing a normal service to the user.

In various embodiments of the present invention, the following mechanism is proposed to prevent the recovery delay:

Step 1: If a finger printed CSG belonging to another PLMN is identified, the UE stores the current RPLMN before triggering registration in the CSG cell.

Step 2: When the UE leaves the service area of the CSG cell of another PLMN, in order to prevent temporary service interruption of the cell in various ways, the UE attempts to search for the currently selected CSG cell using a fast scan mechanism can do.

Step 3: If the CSG cell is not found, the UE checks the stored RPLMN (eg, the PLMN prior to being reselected as the CSG of another PLMN) and the priority of the other PLMN. A fast scan may be performed to retrieve the priorities of the previous PLMN and the current PLMN. For example, when the priority of the previous PLMN is higher than that of the current PLMN, the previous PLMN is first searched, and if the previous PLMN cannot be found, the current PLMN is searched. The fast scan mechanism is not limited to a stored frequency scan or any other algorithm.

Step 4: If the UE does not receive normal service due to a discovery procedure failure or registration failure during high-speed scan, the UE may start the RPLMN recovery mechanism with the previous PLMN according to Section 4.4.3.1 of TS 23.122.

2 is a block diagram illustrating a radio protocol architecture for a user plane. 3 is a block diagram illustrating a radio protocol structure for a control plane. The data plane is a protocol stack for user data transmission, and the control plane is a protocol stack for control signal transmission.

2 and 3 , a physical layer (PHY (physical) layer) provides an information transfer service to an upper layer by using a physical channel. The physical layer is connected to a medium access control (MAC) layer, which is an upper layer, through a transport channel. Data moves between the MAC layer and the physical layer through the transport channel. Transmission channels are classified according to how and with what characteristics data are transmitted through the air interface.

Data moves through physical channels between different physical layers, that is, between the physical layers of the transmitter and the receiver. The physical channel is modulated by OFDM (Orthogonal Frequency Division Multiplexing), and time and frequency are used as radio resources.

The 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 logical channels. The MAC layer provides a service to the RLC (Radio Link Control) layer through a logical channel.

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

In order to guarantee the various QoS (Quality of Service) required by the Radio Bearer (RB), the RLC layer has a transparent mode (Transparent Mode, TM), an unacknowledged mode (Unacknowledged Mode, UM) and an acknowledged mode (Acknowledged Mode). , AM) provides three operation modes. 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 Packet Data Convergence Protocol (PDCP) layer in the user plane include transmission 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 controlling logical channels, transport channels and physical channels in relation to configuration, re-configuration, and release of radio bearers. RB means a logical path provided by the first layer (PHY layer) and the second layer (MAC layer, RLC layer, PDCP layer) for data transfer between the terminal and the network. Setting the RB means defining the characteristics of a radio protocol layer and channel to provide a specific service, and setting each specific parameter and operation method. The RB may be further divided into a signaling RB (SRB) and a data RB (DRB). The SRB is used as a path for transmitting an RRC message in the control plane, and the DRB is used as a path for transmitting user data in the user plane.

If there is an RRC connection between the RRC layer of the terminal and the RRC layer of the E-UTRAN, the terminal is in the RRC connected state (RRC_CONNECTED), otherwise it is in the RRC idle state (RRC_IDLE).

As a downlink transmission channel for transmitting data from a network to a terminal, there are a BCH (Broadcast Channel) for transmitting system information and a downlink SCH (Shared Channel) for transmitting user traffic or control messages. Traffic or control messages of downlink multicast or broadcast services may be transmitted through a downlink SCH or may be transmitted through a separate downlink multicast channel (MCH). On the other hand, as an uplink transport channel for transmitting data from the terminal to the network, there are a random access channel (RACH) for transmitting an initial control message and an uplink shared channel (SCH) for transmitting user traffic or control messages.

It is located above the transport channel, and as a logical channel mapped to the transport channel, BCCH (Broadcast Control Channel), PCCH (Paging Control Channel), CCCH (Common Control Channel), MCCH (Multicast Control Channel), MTCH (Multicast Traffic Channel), etc.

A physical channel is composed of several symbols in the time domain and several subcarriers in the frequency domain. One sub-frame is composed of a plurality of symbols in the time domain. One subframe is composed of a plurality of resource blocks (Resource Block), and one resource block is composed of a plurality of symbols and a plurality of sub-carriers. In addition, each subframe may use specific subcarriers of specific symbols (eg, the first symbol) of the corresponding subframe for a Physical Downlink Control Channel (PDCCH), that is, an L1/L2 control channel. A transmission time interval (TTI), which is a unit time for data transmission, is 1 ms corresponding to one subframe.

Hereinafter, the RRC state of the terminal and the RRC connection method will be described in detail.

RRC state refers to whether or not the RRC layer of the UE is logically connected to the RRC layer of the E-UTRAN. If connected, the RRC connected state (RRC_CONNECTED state), if not connected, the RRC idle state. It is called (RRC_IDLE state). Since the UE in the RRC_CONNECTED state has an RRC connection, the E-UTRAN can determine the existence of the UE on a cell-by-cell basis, and thus can effectively control the UE. On the other hand, the UE in the RRC_IDLE state cannot be identified by the E-UTRAN, and is managed by the core network in a tracking area unit, which is a larger area unit than the cell. That is, the UE in the RRC_IDLE state is only checked whether it exists in a large area unit, and must move to the RRC_CONNECTED state in order to receive a normal mobile communication service such as voice or data.

When the user turns on the terminal for the first time, the terminal first searches for an appropriate cell and then stays in the RRC_IDLE state in the corresponding cell. When the UE that stayed in the RRC_IDLE state needs to establish an RRC connection, it establishes an RRC connection with the E-UTRAN through an RRC connection procedure and transitions to the RRC_CONNECTED state. There are several cases in which the UE in the RRC_IDLE state needs to establish an RRC connection. For example, uplink data transmission is required due to a user's call attempt, or a paging message is received from the E-UTRAN. In one case, a response message may be transmitted.

The NAS (Non-Access Stratum) layer located above the RRC layer performs functions such as session management and mobility management.

Two states, EMM-REGISTERED (EPS Mobility Management-REGISTERED) and EMM-DEREGISTERED, are defined to manage the mobility of the UE in the NAS layer, and these two states are applied to the UE and the MME. The initial terminal is in the EMMDEREGISTERED state, and in order for the terminal to access the network, it performs a process of registering with the corresponding network through the Initial Attach procedure. When the attach procedure is successfully performed, the terminal and the MME enter the EMMREGISTERED state.

In order to manage the signaling connection between the UE and the EPC, two states are defined: an EPS Connection Management (ECM)-IDLE state and an ECM-CONNECTED state, and these two states are applied to the UE and the MME. When the UE in the ECMIDLE state establishes an RRC connection with the E-UTRAN, the UE enters the ECM-CONNECTED state. When the MME in the ECM-IDLE state establishes an S1 connection with the E-UTRAN, it enters the ECM-CONNECTED state. When the UE is in the ECM-IDLE state, the E-UTRAN does not have context information of the UE. Therefore, the UE in the ECM-IDLE state performs a UE-based mobility-related procedure such as cell selection or cell reselection without receiving a command from the network. On the other hand, when the terminal is in the ECM-CONNECTED state, the mobility of the terminal is managed by the command of the network. In the ECM-IDLE state, when the location of the terminal is different from the location known by the network, the terminal notifies the network of the corresponding location of the terminal through a tracking area update procedure.

4 illustrates a method for cell reselection in a manual PLMN selection mode according to various embodiments of the present invention. A terminal (UE) implements a NAS layer and an Access Straum (AS) layer. The AS layer refers to a layer below the third layer of the radio interface protocol.

Referring to 4 above, CSG finger information may be determined in the AS layer of the terminal. For example, the CSG finger information means CSG information associated with the PLMN detected at the current location of the terminal. The CSG whitelist may be provided from the network.

First, it is assumed that the terminal is set to the manual PLMN selection mode and is registered in the first PLMN.

In this case, since CSGs related to the second PLMN are included in the conventional CSG whitelist, the automatic search function may be performed in the terminal in the manual PLMN selection mode and registered in the CSG related to the second PLMN.

Accordingly, in the present invention, in order to prevent the UE from being registered with another PLMN in the manual PLMN selection mode, the UE may modify the CSG whitelist to include only the PLMN currently registered and the PLMN equivalent thereto in the CSG whitelist.

Therefore, even if the CSG 21 related to the second PLMN is identified, the UE will not trigger the automatic search function because the CSGs related to the second PLMN are not included in the CSG whitelist.

Accordingly, the terminal may maintain the first PLMN registration state in the manual PLMN selection mode.

5 illustrates a method for cell reselection in a manual PLMN selection mode according to various embodiments of the present invention.

Referring to 5, similar to the environment of FIG. 4, and in other various embodiments, in order to prevent the terminal from being registered with another PLMN in the manual PLMN selection mode, instead of modifying the CSG whitelist, the terminal uses the manual In the PLMN selection mode, it is determined whether a CSG related to a PLMN other than the current PLMN is in the CSG finger information, so that the automatic search function is not started. For example, when the terminal is in the manual PLMN selection mode and a CSG related to a PLMN other than the current PLMN is included in the CSG finger information, the automatic search function may be disabled.

Therefore, even if the CSG 21 related to the second PLMN is identified, if the AS of the terminal informs the NAS of the CSG 21 related to the second PLMN, the NAS of the terminal indicates that the CSG related to the PLMN other than the current PLMN is in the CSG finger information. can be recognized, so the automatic search function can be disabled.

Accordingly, the terminal may maintain the first PLMN registration state in the manual PLMN selection mode.

6 illustrates a method for preventing a recovery procedure from being delayed when leaving a CSG cell in an automatic PLMN selection mode according to various embodiments of the present invention.

Referring to 6 above, it is first assumed that the terminal is set to the automatic PLMN selection mode and is registered with the first PLMN.

When the CSG 21 related to the second PLMN is identified, the automatic search function is triggered to notify the CSG 21 related to the second PLMN from the AS of the terminal to the NAS (CSG FINGER PRINT INDICATION), and the NAS is the currently registered PLMN (eg, the first PLMN) is stored. This is to prevent a recovery delay when the UE moves out of the CSG cell of the second PLMN after moving to a CSG associated with another PLMN (eg, the second PLMN) later.

Next, the NAS of the terminal searches for the CSG 21 related to the second PLMN and reports the result to the AS, and the AS of the terminal selects the CSG 21 related to the second PLMN and provides CELL_IND information to the NAS. Thereafter, the NAS requests a registration update from the second PLMN and receives a response to the registration update from the second PLMN, so that the terminal is registered with the second PLMN.

Afterwards, when the terminal leaves the CSG cell of the second PLMN, the AS of the terminal notifies the NAS, then the NAS of the terminal performs a high-speed scan on the CSG 21 related to the second PLMN, and the result is AS to the NAS, and the AS can notify the search failure message to the NAS.

If the CSG 21 associated with the second PLMN is not found, the UE may perform a recovery algorithm by checking the priorities of the stored RPLMN (eg, the first PLMN) and the second PLMN. For a detailed description of the recovery algorithm, reference will be made to FIG. 11 below.

A fast scan may be done to retrieve the priorities of the previous PLMN and the current PLMN. For example, when the priority of the previous PLMN is higher than that of the current PLMN, the previous PLMN is first searched, and if the previous PLMN cannot be found, the current PLMN is searched. The fast scan mechanism is not limited to a stored frequency scan or any other algorithm.

If the UE does not receive normal service due to a search procedure failure or registration failure during a high-speed scan, the UE may use the recovery mechanism described in Section 4.4.3.1 of TS 23.122 based on the first PLMN.

7 is a flowchart for cell reselection in the manual PLMN selection mode according to various embodiments of the present invention.

Referring to 7 above, the terminal checks the network selection mode in operation 700 . The network selection mode may be one of a manual PLMN selection mode and an automatic PLMN selection mode.

In operation 702, the UE may check whether another PLMN in the currently registered PLMN or a PLMN equivalent to the currently registered PLMN exists in the CSG finger print information.

In operation 704 , the terminal may disable the automatic search function according to the check result. For example, when the terminal is in manual PLMN selection mode and another PLMN from the currently registered PLMN is included in CSG finger print information, the automatic search function (ASF) is disabled, and the terminal is in automatic PLMN selection mode or currently registered When another PLMN is included in the CSG finger print information in the selected PLMN (that is, when only the currently registered PLMN and its equivalent PLMN are included in the CSG finger print information), the automatic search function (ASF) is not disabled. .

8 is a flowchart for cell reselection in the manual PLMN selection mode according to various embodiments of the present invention.

Referring to 8, when the terminal is in the manual PLMN selection mode in operation 800, and another PLMN from the currently registered PLMN is included in the CSG finger print information, only the currently registered PLMN and its equivalent PLMN are CSG whitelist It can be modified to be included in

The UE stops the triggering of the automatic search function when the CSG related to the PLMN that is not in the CSG whitelist is identified in operation 802. That is, even if CSGs related to other PLMNs are identified, the automatic search function will not be triggered because CSGs related to other PLMNs are not included in the CSG whitelist.

In operation 804, the UE may maintain a state camped on the previous PLMN when a CSG related to another PLMN is identified in the manual PLMN selection mode.

9 is a flowchart for cell reselection in the manual PLMN selection mode according to various embodiments of the present invention.

Referring to 9 above, the terminal checks whether a CSG associated with another PLMN is identified based on the finger print information in operation 900, and when a CSG associated with another PLMN is identified in operation 902, does not start the automatic search function in the manual PLMN selection mode. Otherwise, in operation 904, the current state is maintained. For example, in an environment in which the terminal is registered in the first PLNM and is set to the manual PLMN selection mode, when the CSG associated with the second PLMN is identified, the terminal in the manual PLMN selection mode maintains the first PLNM registration state.

10 is a flowchart for preventing the recovery procedure from being delayed when leaving the CSG cell in the automatic PLMN selection mode according to various embodiments of the present invention.

Referring to 10, the UE performs a registration procedure with the first PLMN in operation 1000, and the UE checks whether a CSG related to the second PLMN is identified in operation 1002.

When the CSG related to the second PLMN is identified in operation 1004, the UE stores information on the first PLMN.

The UE performs a registration procedure with the CSG related to the second PLMN in operation 1006 .

The terminal checks whether it leaves the service area of the CSG associated with the second PLMN in operation 1008, and when the terminal leaves the service area of the CSG associated with the second PLMN in operation 1010, the recovery algorithm of FIG. 11 may be performed.

11 shows a flowchart for a recovery algorithm according to various embodiments of the present invention.

Referring to 11 above, the UE performs cell reselection from the first PLMN region to the CSG region related to the second PLMN in operation 1100 .

The UE checks whether it leaves the service area of the CSG associated with the second PLMN in operation 1102, and compares the priorities of the first PLMN and the second PLMN in operation 1104 when leaving the service area of the CSG associated with the second PLMN. On the other hand, if the service area of the CSG related to the second PLMN does not deviate, operation 1100 may be maintained.

When the priority of the first PLMN is higher than that of the second PLMN, the UE performs a high-speed scan based on the first PLMN in operation 1106 . In operation 1108, when registration in the first PLMN is successful, the recovery algorithm is terminated, in operation 1110 when registration in the first PLMN fails, a high-speed scan is performed based on the second PLMN, in operation 1112, when registration in the second PLMN is successful, the recovery algorithm is terminated , and when registration to the second PLMN fails, operation 1114 is performed.

When the priority of the second PLMN is higher than that of the first PLMN, the UE performs a high-speed scan based on the second PLMN in operation 1118 . In operation 1120, when registration in the second PLMN is successful, the recovery algorithm is terminated, in operation 1122 when registration in the second PLMN fails, a high-speed scan is performed based on the first PLMN, in operation 1114, when registration in the first PLMN is successful, the recovery algorithm is , and if registration in 1 PLMN fails, operation 1114 is performed.

The UE registers as a registration PLMN with the pre-stored first PLMN in operation 1114 and performs the procedure described in TS 23.122 based on the first PLMN in operation 1116 .

12 is a functional block diagram of a terminal according to various embodiments of the present invention.

Referring to FIG. 12 , the terminal includes a controller 1200 , a storage 1202 , a receiver 1204 , and a transmitter 1206 . The controller 1200 may control an operation for cell reselection in a wireless communication system according to various embodiments of the present disclosure. For example, the controller 1200 controls the operation according to the flow shown in FIGS. 4 to 9 to be performed. The receiver 1204 receives data or a control signal based on a corresponding communication method under the control of the controller 1200 , and the transmitter 1206 transmits the data or control signal under the control of the controller 1200 based on the corresponding communication method can do. The receiver 1204 may receive cell identifier information from a serving cell or an adjacent cell, and the controller 1200 may determine the PLMN macro cell or CSGs around the terminal based on the received cell identifier information.

The controller 1200 may modify the CSG whitelist of the terminal based on the PLMN selection mode. For example, when operating in the MANUAL PLMN selection mode, the controller 1200 may limit the CSG whitelist to include only currently registered PLMNs and their equivalent PLMNs. If the user changes to the automatic PLMN selection mode, selects another PLMN, or the list of PLMNs equivalent to the currently registered PLMN is changed, the controller 1200 may update the CSG whitelist again. In automatic PLMN selection mode, there is no restriction on CSG whitelist update, and all entries in allowed CSG list and operator CSG list can be updated according to TS 23.122.

Also, when a finger printed CSG belonging to another PLMN is identified, the controller 1200 cannot immediately perform a PLMN search by itself. This may be determined in consideration of the current operation mode. For example, when the controller 1200 is in the manual PLMN selection mode and the detected finger printed CSG is a CSG of another PLMN as well as a currently registered PLMN or its equivalent PLMN, the controller 1200 controls an automatic search function (ASF). ) is not allowed. Accordingly, the controller 1200 does not select a finger printed CSG cell of another PLMN.

In addition, the controller 1200 may perform the following mechanism to prevent recovery delay. When a finger printed CSG belonging to another PLMN is identified, the control unit 1200 stores the current RPLMN before triggering registration in the CSG cell, and when the terminal deviates from the service area of the CSG cell of another PLMN, the cell in various ways In order to prevent temporary service interruption, the UE attempts to search for the currently selected CSG cell using a fast scan mechanism, and if the CSG cell is not found, the stored RPLMN (eg, CSG of another PLMN) Priority of the PLMN before being selected) and the other PLMNs may be checked, and a high-speed scan may be performed. For example, when the priority of the previous PLMN is higher than that of the current PLMN, the previous PLMN is first searched, and if the previous PLMN cannot be found, the current PLMN is searched. And, when the terminal does not receive a normal service due to a search procedure failure or registration failure during the high-speed scan, the controller 1200 may start the RPLMN recovery mechanism with the previous PLMN according to Section 4.4.3.1 of TS 23.122.

In addition, the operations according to the embodiment of the present invention may be implemented by a single processor. In this case, program instructions for performing various computer-implemented operations may be recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions may be specially designed and configured for the present invention, or may be known and used by those skilled in the art. Examples of the computer-readable recording medium include a hard disk, a magnetic medium such as a floppy disk and a magnetic tape, an optical recording medium such as a CD-ROM or DVD, a magneto-optical medium such as a floppy disk, and a ROM. hardware devices specially configured to store and execute program instructions, such as , RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. When all or part of the base station or relay described in the present invention is implemented as a computer program, a computer-readable recording medium storing the computer program is also included in the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the following claims as well as the claims and equivalents.

30: MME/S-GW, 20: BS
10: HNB
1200: control unit, 1202: storage unit
1204: receiver 1206: transmitter

Claims (20)

In the method of the terminal for cell reselection,
checking the network selection mode;
determining a closed subscriber group (CSG) cell list detected at the location of the terminal;
identifying whether at least one CSG cell is included in the CSG cell list, the at least one CSG cell comprising a CSG cell associated with a second public land mobile network (PLMN);
When the network selection mode is the manual PLMN selection mode and the at least one CSG cell is included in the CSG cell list, controlling an automatic search function (ASF) for cell reselection not to operate including,
The second PLMN is a PLMN different from the first PLMN,
The first PLMN is a PLMN to which the terminal is registered.
The method according to claim 1,
The step of controlling the automatic search function not to operate includes:
and modifying the CSG whitelist so that only the first PLMN registered by the terminal and a PLMN equivalent thereto are included.
3. The method according to claim 2,
and restoring the CSG whitelist when the network selection mode is changed to an automatic PLMN selection mode.
The method according to claim 1,
The step of controlling the automatic search function not to operate includes:
prior to triggering the auto-discovery function, determining whether to trigger the auto-discovery function.
The method according to claim 1,
and controlling the automatic search function to operate when the network selection mode is an automatic PLMN selection mode or the at least one CSG cell associated with the second PLMN is not identified.
The method according to claim 1,
when the network selection mode is an automatic PLMN selection mode, performing the automatic search function to select a CSG cell associated with another PLMN;
Before registration to the CSG cell associated with the other PLMN is started, the method further comprising the step of storing, by the terminal, information on the registered first PLMN.
7. The method of claim 6,
The method further comprising the step of recovering to the first PLMN by using the stored information on the first PLMN according to a predefined procedure when registration to the CSG cell associated with the other PLMN fails.
7. The method of claim 6,
and, after successful registration to the CSG cell associated with the other PLMN, when the registration is out of the service area of the successful CSG cell, re-searching to the CSG cell in which the registration was successful.
9. The method of claim 8,
The step of trying to search again to the CSG cell in which the registration has been successful comprises:
checking the priority of available PLMNs;
retrieving PLMNs according to priority.
The method according to claim 1,
When at least one CSG ID related to at least PLMN identity is included in the CSG whitelist, performing the automatic search function to detect previously visited CSG member cells.
In the apparatus for cell reselection of a terminal,
transceiver; and
at least one control unit, wherein the at least one control unit comprises:
Check the network selection mode,
determining a closed subscriber group (CSG) cell list detected at the location of the terminal;
Identifies whether at least one CSG cell is included in the CSG cell list, the at least one CSG cell includes a CSG cell associated with a second public land mobile network (PLMN);
When the network selection mode is a manual PLMN selection mode and the at least one CSG cell is included in the CSG cell list, an automatic search function (ASF) for cell reselection is not operated.
The second PLMN is a PLMN different from the first PLMN,
The first PLMN is a PLMN to which the terminal is registered.
12. The method of claim 11,
The at least one control unit,
In order to control the automatic search function not to operate,
An apparatus for modifying a CSG whitelist so that only the first PLMN registered with the terminal and a PLMN equivalent thereto are included.
13. The method of claim 12,
The at least one control unit,
When the network selection mode is changed to an automatic PLMN selection mode, the apparatus for restoring the CSG whitelist.
12. The method of claim 11,
In order to control the at least one control unit not to operate the automatic search function,
Before triggering the auto-discovery function, an apparatus for determining whether to trigger the auto-discovery function.
12. The method of claim 11,
The at least one control unit,
When the network selection mode is an automatic PLMN selection mode or the at least one CSG cell associated with the second PLMN is not identified, the apparatus for controlling to operate the automatic search function.
12. The method of claim 11,
The at least one control unit,
When the network selection mode is an automatic PLMN selection mode, performing the automatic search function to select a CSG cell associated with another PLMN;
Before registration to the CSG cell associated with the other PLMN starts, the terminal stores information on the first PLMN to which the terminal is registered.
17. The method of claim 16,
The at least one control unit,
When registration to the CSG cell associated with the other PLMN fails, the apparatus recovers to the first PLMN by using the stored information on the first PLMN according to a predefined procedure.
17. The method of claim 16,
The at least one control unit,
After successful registration to the CSG cell associated with the other PLMN, if the registration is out of the service area of the successful CSG cell, the apparatus attempts to search again to the CSG cell in which the registration was successful.
19. The method of claim 18,
The at least one control unit,
To try to search again to the CSG cell where the registration was successful,
Check the priority of available PLMNs,
A device that searches for PLMNs according to priority.
The method according to claim 11, wherein the at least one control unit,
When at least one CSG ID related to at least PLMN identity is included in the CSG whitelist, the apparatus for performing the automatic search function to detect previously visited CSG member cells.

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