KR20180033437A - Methods for changing a connection state of a UE and Apparatuses thereof - Google Patents

Abstract

The present invention relates to a method for changing a connection state according to a movement of a terminal and an apparatus thereof, and more specifically, to a method and apparatus for determining a connection state of a corresponding terminal when a terminal in a right connection or RRC inactive state is moved and reflecting the same. Particularly, the method for changing a connection state of a terminal comprises: a step of receiving instruction information indicating a state change to a specific RRC state from a base station; a step of configuring a connection state of a terminal to the specific RRC state based on the instruction information and performing a cell re-selection operation according to a movement of the terminal; and a connection state change step of changing the connection state of the terminal to an RRC idle state based on at least one among information on whether to initiate an RRC resumption procedure, system information of a cell selected according to the cell re-selection operation, and radio access technology information. The specific RRC state is distinguished from an RRC connection state and the RRC idle state.

Description

[0001] The present invention relates to a method and apparatus for changing a connection state of a UE,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a connection state changing method and apparatus according to movement of a terminal. And more particularly, to a method and apparatus for determining a connection state of a terminal in a state of a write connection or an RRC inactive state and reflecting the determination.

As communications systems evolved, consumers, such as businesses and individuals, used a wide variety of wireless terminals. In a mobile communication system such as LTE (Long Term Evolution) and LTE-Advanced of the current 3GPP series, a high-speed and large-capacity communication system capable of transmitting and receiving various data such as video and wireless data outside a voice- It is required to develop a technique capable of transmitting large-capacity data in accordance with the above-described method.

In addition, due to the increase of terminals using machine type communication (hereinafter referred to as "MTC" communication), data transmission / reception through a mobile communication system is rapidly increasing. Meanwhile, in the case of MTC communication, it is necessary to periodically transmit and receive a small amount of data, and a low-power low-cost terminal can be used.

Therefore, there is a demand for a technology for transmitting and receiving data by a plurality of terminals while reducing power consumption.

In particular, in the case of a terminal that transmits a small amount of data periodically or aperiodically, it is necessary to change the RRC connection state in order to transmit a small amount of data. However, in order to change the RRC connection state by the conventional method, the data transmission / reception procedure of the terminal, the base station, the base station, and the core network has been complicated.

Such a transmission / reception procedure causes a relatively high data load compared to a small amount of data to be transmitted by the terminal. That is, there is a problem that unnecessary data overload occurs in the RRC connection state change procedure for transmitting a small amount of data.

This problem is likely to result in an increase in data load throughout the communication system as the number of terminals for transmitting a small amount of data periodically increases.

Therefore, it is necessary to study a method and a procedure for changing the terminal connection state, which can transmit and receive a small amount of data without seriously increasing the data load of the entire communication system according to the change of the wireless communication environment. In particular, when a new RRC state other than RRC connection and RRC idle state is defined and the UE configures the connection state, a specific connection state change procedure is required.

In the above-described background, when a new terminal connection state is added such as a light connection state or an RRC inactive state in addition to the RRC connection and the RRC idle, We propose a connection state change procedure according to the movement of the terminal.

According to an embodiment of the present invention, there is provided a method of changing a connection state of a terminal, the method comprising: receiving instruction information for instructing a state change from a base station to a specific RRC state; A step of configuring the connection state into a specific RRC state, performing a cell reselection operation according to the movement of the terminal, information on whether or not to start the RRC restart procedure, system information of the selected cell according to the cell re- And a connection state changing step of changing a connection state of the UE to an RRC idle state based on at least one of the RRC idle state and the RRC idle state, ≪ / RTI >

According to another aspect of the present invention, there is provided a method of controlling a connection state change of a terminal in a base station, the method comprising: transmitting information on whether a specific RRC state is supported by a corresponding cell provided by the base station, Comprising the steps of: transmitting indication information indicating a state change to a specific RRC state to a terminal; and configuring a connection state of the terminal to a specific RRC state, wherein the specific RRC state includes an RRC connection state and an RRC idle state, And a state in which the first and second electrodes are separated from each other.

According to an embodiment of the present invention, in a terminal that changes a connection state, a connection state of a terminal is configured to a specific RRC state based on a reception unit that receives instruction information that instructs a state change from a base station to a specific RRC state, And a controller for performing a cell reselection operation according to the movement of the terminal, wherein the controller is configured to perform a cell reselection operation based on at least one of information on whether or not to initiate the RRC resumption procedure, system information of the selected cell according to the cell re- And changes the connection state of the terminal to the RRC idle state, and the specific RRC state is a state distinguished from the RRC connection state and the RRC idle state.

According to an embodiment of the present invention, a base station for controlling a connection state change of a terminal transmits information on whether a specific RRC state of a cell provided by the corresponding base station is supported through system information, A transmission unit for transmitting indication information indicating a state change to an RRC state, and a controller for configuring a connection state of the terminal into a specific RRC state, wherein the specific RRC state includes a state in which the RRC connection state and the RRC idle state are distinguished from each other And a base station apparatus.

The embodiments described above provide a reduced signaling procedure for a terminal that performs frequent connection state changes and clarify the operation procedure when a terminal moves, thereby reducing ambiguity while reducing the data load of the entire communication system Provides a possible effect.

1 is a diagram for explaining a message processing procedure according to the conventional LTE technology.
2 is a diagram for explaining a UE initiated connection resume procedure according to the related art.
3 is a diagram for explaining a terminal operation according to an embodiment.
4 is a view for explaining a base station operation according to an embodiment.
5 is a diagram for explaining a terminal configuration according to an embodiment.
6 is a view for explaining a base station configuration according to an embodiment.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Herein, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In this specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, the MTC terminal may refer to a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, the MTC terminal in this specification may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC-related operations. Alternatively, the MTC terminal may support enhanced coverage over the existing LTE coverage or a UE category / type defined in the existing 3GPP Release-12 or lower that supports low power consumption, or a newly defined Release-13 low cost low complexity UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data and the like. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, in the present specification, a base station or a cell has a comprehensive meaning indicating a part or function covered by BSC (Base Station Controller) in CDMA, Node-B in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) the device itself providing a megacell, macrocell, microcell, picocell, femtocell, small cell in relation to the wireless region, or ii) indicating the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a base station, collectively referred to as a megacell, macrocell, microcell, picocell, femtocell, small cell, RRH, antenna, RU, low power node do.

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

In systems such as LTE and LTE-advanced, a standard is constructed by configuring uplink and downlink based on a single carrier or carrier pair. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

On the other hand, control information can also be transmitted using EPDCCH (enhanced PDCCH or extended PDCCH).

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or transmission / reception point of a signal transmitted from a transmission / reception point, and a transmission / reception point itself .

The wireless communication system to which the embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-point transmission / reception system in which two or more transmission / reception points cooperatively transmit signals. antenna transmission system, or a cooperative multi-cell communication system. A CoMP system may include at least two multipoint transmit and receive points and terminals.

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

Hereinafter, a downlink refers to a communication or communication path from a multipoint transmission / reception point to a terminal, and an uplink refers to a communication or communication path from a terminal to a multiple transmission / reception point. In the downlink, a transmitter may be a part of a multipoint transmission / reception point, and a receiver may be a part of a terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, EPDCCH, which is an embodiment of the present invention, may be applied to the portion described with PDCCH, and EPDCCH may be applied to the portion described with EPDCCH according to an embodiment of the present invention.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of a PDSCH, A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

The connection state transition procedure of the terminal

In the conventional mobile communication technology, a terminal and a network state are classified into a terminal idle state and a connected state. The terminal and the network state coincide. For example, the states in the radio network (E-UTRAN) and the core network (for example, the RRC state and the ECM state) coincide. That is, when the UE transits to the RRC-IDLE state, the UE enters the ECM-IDLE state. When the UE transitions to the RRC-CONNECTED state, the UE enters the ECM-CONNECTED state. The terminal in the idle state has to perform a complicated signaling process as shown in FIG. 1 in order to transmit data according to the terminal state. In particular, when a terminal transmits a small amount of data, it becomes a large overhead.

1 is a diagram for explaining a message processing procedure according to the conventional LTE technology.

Referring to FIG. 1, the MS 100 transmits a random access preamble to the BS 110 in order to transmit data by transiting from the RRC idle state to the RRC connected state (S100). Then, the terminal 100 receives a random access response from the base station 110 (S101) and requests the base station 110 to establish an RRC connection (S102).

The base station 110 sets up an RRC connection setup in the terminal 100 (S103), and the terminal 100 reports completion (S104).

When the RRC connection setup is completed, the base station 110 transmits an initial terminal message to the MME 120 to request a service (S105). The MME 120 requests the base station 110 to perform initial context setup (S107). Between step S105 and step S107, the base station 110 may transmit the RRC connection reconfiguration message to the terminal 100 to set the measurement configuration (S106). When the measurement configuration is completed, the UE 100 transmits an RRC connection reconfiguration message to the BS 110 (S108).

The base station 110 transmits a security mode command of the terminal 100 (S109), and receives a response thereto (S110).

Thereafter, the BS 110 transmits an RRC connection reconfiguration message to the UE 100 for setting up the RB (S111), and receives a response to the RRC connection reconfiguration message (S112). The base station 110 transmits a response to the initial context setup to the MME 120 in step S113 and the MME 120 transmits the bearer modification request to the gateway 130 in step S114.

The terminal 100 transmits a UDP / IP packet to the base station 110 in step S115 and the base station 110 transmits the packet to the gateway 130 in step S116. The gateway 130 transmits a response to the bearer modification to the MME 120 (S117), and transmits a UDP / IP packet response to the base station 110 (S118). The base station 110 transmits the packet to the terminal 100 (S119).

Through this procedure, the AT 100 transmits the packet to the core network.

Thereafter, the terminal 100 transmits a measurement report to the base station 120 periodically or at the time of occurrence of an event according to the measurement configuration (S120). The base station 120 determines whether to release the terminal 100 based on the measurement report or deactivation timer (S121). When the RRC connection release of the terminal 100 is determined, the base station 110 requests the MME 120 to release the terminal context (S122). The MME 120 instructs the base station 110 to release the terminal context (S123), and the base station 110 instructs the terminal 100 to release the RRC connection accordingly (S124).

After releasing the RRC connection of the terminal 100, the base station 110 transmits a response to the MME 120 (S125).

Through this procedure, the RRC connection terminal can be transited to the RRC idle state.

As described above, in the prior art, a plurality of signaling procedures are required between the UE, the BS, the BS, and the core network in order for the UE to transition from the RRC idle state to the RRC connected state or from the RRC connected state to the RRC idle state. In this procedure, when the UE periodically transmits a small amount of data, the overhead continuously occurs. Meanwhile, in order to reduce the overhead due to the state transition, the UE can be maintained in a connected state. In this case, even when there is no data transmission, it is necessary to periodically measure the network status according to the measurement configuration, Consumption may be caused. In addition, when the RRC connection state is maintained, the handover signaling overhead due to the movement of the UE increases.

Connection state transition procedure for NB-IoT terminal

A narrow band IoT terminal may be operated in a fixed state and may be installed in a specific location or located within a certain range. Due to this characteristic, the NB-IoT terminal and the base station support the Suspend / Resume procedure. In the RRC connection release message, the base station can request the terminal to maintain an AS context in the RRC_IDLE state. When the UE receives the RRC connection release message including the RRC suspend information and transitions to the RRC IDLE state (or before the BS sends the message to the UE), the BS transmits an S1 message to the core network The ECM enters the IDLE state.

The RRC connection resume procedure is used for the RRC Connected transition in the RRC IDLE used to resume the RRC connection previously stored in the terminal and the base station. When the MS initiates the RRC connection resume procedure and transitions to the RRC Connected state (after the BS sends an RRC connection resume message to the MS), the BS sends an S1 message requesting state transition of the MS to the core network to transmit the ECM CONNECTED state ≪ / RTI >

2 is a diagram for explaining a UE initiated connection resume procedure according to the related art.

Referring to FIG. 2, the terminal 200 performs a random access procedure with the base station 210 (S200). Thereafter, the MS 200 initiates an RRC connection resumption procedure with the BS 210 to resume the RRC connection (S210).

The base station 210 transmits an S1-AP terminal context resume request to the MME 215 in step S220 and receives an S1-AP terminal context resume response in step S230. Upon receiving the terminal context resumption response, the BS 210 can change the connection state of the AT 200 to the RRC connection state by performing the RRC reconfiguration procedure with the AT 200. [

The terminal 200 then transmits the uplink data to the core network through the base station 210, the MME 215, the serving gateway 220 and the PDN gateway 225. The MME 225 transmits a modified bearer request to the serving gateway 220 (S260) and receives a modified bearer response from the serving gateway 220 (S270).

Through the above procedure, the terminal (for example, the NB-IoT terminal) can resume the RRC connection and transmit / receive data.

However, even in this case, the RRC connection state and the ECM connection state are made the same, and thus unnecessary overhead is generated between the base station and the core network. That is, as described above, in the conventional mobile communication technology, there is a signaling overhead problem due to state transition, and in the case of the Suspend / Resume procedure for the terminal in the fixed location which can reduce the overhead, the NB-IoT terminal can be applied . Accordingly, when the UE moves out of a cell (or a base station) providing the previously stored AS Context, the UE has to perform the service request procedure as shown in FIG. 1 to transmit the uplink data. In addition, since the transition between the Suspend state and the Resume state is the same as the transition between the IDLE state and the CONNECTED state, the core network signaling (S1 signaling) is continuously generated.

In order to solve this problem, we propose a concrete procedure for transiting only the wireless network connection state without core network signaling. In order to reflect the mobility of the terminal, a specific connection state changing procedure according to the movement of the terminal having a specific RRC connection state is provided.

The embodiments described below can be applied to terminals using all mobile communication technologies. For example, the present embodiments can be applied not only to mobile communication terminals to which LTE technology is applied but also to next generation mobile communication (e.g., 5G mobile communication, New-RAT) terminals. For convenience of description, the base station may represent an eNode-B of an LTE / E-UTRAN, a base station (CU, DU, or CU) in a 5G wireless network in which a CU (Central Unit) DU is an entity implemented as a single logical entity), gNB.

In addition, the specific RRC state described in this specification means a separate RRC state that is distinguished from the conventional RRC connected state and the RRC idle state. For example, a particular RRC state refers to an RRC state where a terminal or base station stores a terminal context and supports RAN initiation paging operations. That is, the RRC state can be divided into three types: RRC connection, RRC idle, and specific RRC state. The specific RRC state is an arbitrary term for defining a new RRC state including the above-mentioned characteristic, and is not limited to that term. For example, a particular RRC state may be referred to as a write connection state or an RRC active state.

Hereinafter, a specific RRC state will be described as a write connection state as necessary, but the same can be applied to an RRC active state applied to the 5G mobile communication technology. Therefore, in the present specification, a specific RRC state, a light connection state, and an RRC active state are used in combination as needed. For convenience of explanation, the description will be focused on the light connection state.

light Connection (Light Connection) state

In 3GPP, research is being conducted on light connection conditions for signaling reduction. The main functions for a lightly connected UE are as follows.

The S1 connection is maintained in an anchor eNB and is in an active state.

- Supports RAN initiation paging.

- The paging procedure is controlled by the anchor base station.

- The RAN-based paging area may be configured to be UE-specific.

- When performing the selly selection based mobility, the same mechanism as the selly selection mechanism of RRC IDLE is used.

The terminal AS context is maintained in at least one of the terminal and the anchor base station.

- In the MME, the ECM state is the ECM-CONNECTED state.

As described above, in the conventional mobile communication technology, there is a signaling overhead problem due to state transition, and a specific RRC state (indicated as a light connection state below for convenience of description) is being performed. When a terminal having a light connection is out of the paging area, the terminal can perform notification (e.g., update the paging area) to the network (or an anchor base station) through the corresponding new cell through selly selection. However, specific methods and procedures for lightweight connection terminals have not been defined. Accordingly, when a terminal with a light connection moves to a cell that does not support a light connection function, communication between a terminal and a network configured with a light connection can not be performed.

It is an object of the present disclosure to solve such a problem to provide a signaling method and a procedure for a terminal having a light connection. And an object of the present invention is to provide an effective processing method in a case where a terminal having a light connection is moved to a cell which does not support a light connection function.

3 is a diagram for explaining a terminal operation according to an embodiment.

Referring to FIG. 3, in step S310, the UE may perform a step of receiving indication information indicating a state change from a base station to a specific RRC state in a method of changing a connection state. For example, a specific RRC state is distinguished from an RRC connection state and an RRC idle state. The terminal context is stored, and a light connection state supporting RAN start paging operation or an RRC active state it means.

Meanwhile, the terminal can receive the instruction information for instructing the terminal to change the connection state of the terminal from the base station to the specific RRC state. For example, the UE can receive the indication information through the RRC message. In this case, the terminal transmits the terminal capability information to the base station in advance to the terminal supporting the specific RRC state, so that the base station can recognize that the terminal supports the specific RRC state.

Then, the terminal may configure a connection state of the terminal to a specific RRC state based on the instruction information, and perform a cell re-selection operation according to the movement of the terminal (S320).

For example, a terminal that has received instruction information for instructing to change a connection state from a base station to a specific RRC state may change the connection state of the terminal to a specific RRC state based on the instruction information. For example, the UE can change the configuration of the UE to change from the RRC connection state to the specific RRC state. As another example, a terminal may store a terminal context, support RAN initiation paging, and suspend all SRBs and DRBs to configure a particular RRC state.

In addition, the terminal can perform movement in a specific RRC state. For example, a UE configured with a specific RRC state can perform a cell reselection operation according to movement. When the radio quality of a cell constituting a specific RRC state drops, the UE can evaluate the radio quality of another cell and perform a cell re-selection operation.

The UE may change the connection state of the UE to the RRC idle state based on at least one of information on whether or not to start the RRC restart procedure, system information of the selected cell according to the cell re-selection operation, (Step S330). For example, the UE can change the connection state of the UE from the RRC state to the RRC idle state or the RRC connected state according to the movement.

For example, the UE may change the connection state of the UE to the RRC idle state when the system information does not include information supporting the specific RRC state. Specifically, the UE can receive the system information of the reselected cell through the cell re-selection operation and check the received system information to confirm that the reselected cell supports the specific RRC state. If the reselected cell does not support a specific RRC state, the terminal may change the specific RRC state to the RRC idle state. This provides the effect of eliminating the connection state ambiguity of the terminal that may occur, since the reselected cell does not support a specific RRC state.

As another example, if the radio access technology of the selected cell is different from the cell constituting the specific RRC state according to the reselection operation, the terminal may change the connection state of the terminal to the RRC idle state. Specifically, the UE confirms the radio access technology of the reselected cell, and can change the connection state of the UE to the RRC idle state when the radio access technology is changed from the previously accessed cell. For example, when a cell in which a UE configures a connection state in a specific RRC state uses an E-UTRAN-based radio access technology and a cell reselected according to movement uses another radio access technology such as WiFi or 3G The terminal may change the connection state to the RRC idle state.

As another example, the UE may change the connection state of the UE to the RRC idle state when the UE initiates the RRC resumption procedure for transition to the RRC connection state before the cell reselection operation. Specifically, the UE may perform an RRC resume procedure to perform a transition from a specific RRC state to an RRC connected state. For example, when origination data (MO data) is generated in a terminal in a specific RRC state, the terminal may change the state of the terminal to the RRC connected state by performing an RRC resume procedure. However, when origination data is generated in a terminal in a specific RRC state or a terminal initiated an RRC resume procedure reselects a cell according to the movement, the terminal can change the connection state to the RRC idle state.

Meanwhile, the UE can perform the paging area update when the UE is out of the RAN start paging area and the system information includes information supporting a specific RRC state. For example, the UE may move out of the RAN start paging area of the base station that configured the specific RRC state according to the movement. In this case, the UE confirms the system information of the reselected cell and checks whether the system information includes information indicating the support of a specific RRC state. If the reselected cell supports a specific RRC state, the terminal can update the paging area. If necessary, the UE can maintain a specific RRC state.

Through this process, even when a terminal configured as a light connection state or an RRC active state moves a cell, the ambiguity of the terminal connection state can be removed in consideration of the system information of the corresponding cell.

Hereinafter, the operation of the base station corresponding to the aforementioned terminal operation will be described with reference to the drawings.

4 is a view for explaining a base station operation according to an embodiment.

Referring to FIG. 4, in a method of controlling connection state change of a UE, a base station can perform a step of transmitting information on whether a specific RRC state of a cell provided by a corresponding base station is supported through system information (S400 ). For example, a specific RRC state is distinguished from an RRC connection state and an RRC idle state. The terminal context is stored, and a light connection state supporting RAN start paging operation or an RRC active state it means.

For example, the base station may transmit information indicating that the cell provided by the base station supports a specific RRC state through the system information. The UE can receive the system information and confirm that the cell supports a specific RRC connection state.

The base station may perform a step of transmitting indication information indicating a state change to a specific RRC state to a terminal in a cell provided by the base station (S410). For example, the base station may transmit indication information via an RRC message. In this case, the base station may receive the terminal capability information including information on whether the terminal supports a specific RRC state, and the base station may recognize that the terminal supports a specific RRC state.

The base station may perform a step of configuring the connection state of the UE to a specific RRC state (S420). For example, the base station may change the connection state of the terminal to a specific RRC state. For example, the base station can change the setting so that the corresponding terminal changes from the RRC connection state to the specific RRC state. In another example, the base station may store the terminal context, support RAN initiation paging, and suspend all SRBs and DRBs to configure a particular RRC state for that terminal.

Meanwhile, the UE can perform the movement in a specific RRC state. For example, a UE configured with a specific RRC state can perform a cell reselection operation according to movement. When the radio quality of a cell constituting a specific RRC state drops, the UE can perform a cell re-selection operation considering the state of another cell.

The UE having the specific RRC state sets the connection state of the UE to the RRC idle state based on at least one of information about whether to start the RRC resumption procedure, system information of the selected cell according to the cell re-selection operation, Can be changed.

For example, the UE may change the connection state of the UE to the RRC idle state when the system information does not include information supporting the specific RRC state. Specifically, the UE can receive the system information of the reselected cell through the cell re-selection operation and check the received system information to confirm that the reselected cell supports the specific RRC state. If the reselected cell does not support a specific RRC state, the terminal may change the specific RRC state to the RRC idle state.

As another example, if the radio access technology of the selected cell is different from the cell constituting the specific RRC state according to the reselection operation, the terminal may change the connection state of the terminal to the RRC idle state. Specifically, the UE confirms the radio access technology of the reselected cell, and can change the connection state of the UE to the RRC idle state when the radio access technology is changed from the previously accessed cell. For example, when a cell in which a UE configures a connection state in a specific RRC state uses an E-UTRAN-based radio access technology and a cell reselected according to movement uses another radio access technology such as WiFi or 3G The terminal may change the connection state to the RRC idle state.

As another example, the UE may change the connection state of the UE to the RRC idle state when the UE initiates the RRC resumption procedure for transition to the RRC connection state before the cell reselection operation. Specifically, the UE may perform an RRC resume procedure to perform a transition from a specific RRC state to an RRC connected state. For example, when origination data (MO data) is generated in a terminal in a specific RRC state, the terminal may change the state of the terminal to the RRC connected state by performing an RRC resume procedure. However, when origination data is generated in a terminal in a specific RRC state or a terminal initiated an RRC resume procedure reselects a cell according to the movement, the terminal can change the connection state to the RRC idle state.

Meanwhile, the UE can perform the paging area update when the UE is out of the RAN start paging area and the system information includes information supporting a specific RRC state. For example, the UE may move out of the RAN start paging area of the base station that configured the specific RRC state according to the movement. In this case, the UE confirms the system information of the reselected cell and checks whether the system information includes information indicating the support of a specific RRC state. If the reselected cell supports a specific RRC state, the terminal can update the paging area. If necessary, the UE can maintain a specific RRC state.

As described above, it is possible to provide a specific RRC state in which unnecessary overhead and time delay can be minimized due to the RRC connection state change of the conventional terminal, and when the terminal of a specific RRC state moves, the RRC connection state It is possible to prevent the occurrence of errors according to the connection state ambiguity of the terminal.

Hereinafter, more specific examples of terminal and base station operations according to movement of a terminal constituting a specific RRC state will be described in detail. Hereinafter, for convenience of description, a specific RRC state will be described as a write connection state. This includes the active state, which is the RRC, as described above, and the term is not limited.

As described above, the selly selection can be triggered as the terminal configured in the light connection state moves.

If a lightly connected state terminal moves out of a cell associated with an anchor base station that has made a light connection state, the anchor base station can not know the position of the lightly connected state terminal. In order for the network to track the location of the lightly connected state terminal, the anchor base station may configure the lightly connected state to the terminal by configuring the paging area in the terminal (for example, The paging area configured in the anchor base station is indicated as the paging area, which is for convenience of description, and other terms of similar concepts are included in the present invention). As an example, the paging area configuration may include information (e.g., a cell list) of one or more cells for the paging area ID. For example, the cell information may be cell identification information or global cell identification information. The paging area configuration information may include anchor base station identification information and terminal identification information in an anchor base station.

For example, the above-described paging area configuration information may be indicated through a UE-specific RRC reconfiguration message. As another example, the above-described paging area configuration information may be indicated through a UE-specific RRC release message. As another example, the above-described paging area configuration information can be indicated through the system information.

According to the cell re-selection criteria, if the terminal finds a better cell, the terminal re-selects the cell. Or the terminal reselects the cell and camps on it. If the terminal is out of the configured paging area (for example, if the reselected cell is not included in at least one paging area information configured in the terminal), the lightly connected terminal must inform the network. For example, a paging area update can be performed. In another example, if the UE does not leave the configured paging area, the UE continues the sellection selection measurement and the selly selection evaluation. When the condition for cell selection is satisfied, the terminal performs cell selection.

If you move to a cell that does not support lightweight connections

Depending on the network construction status, some cells may have a light connection function (RAN paging, X2 paging, light connection status, paging update, network notification, terminal contact (Eg, storing / extracting a stream, supporting mobility based on selly selection, resuming RRC connection, etc.) as a lightweight connection function (for convenience of explanation, other terms can be used) It may not support lightweight connectivity. For example, some CSG cells may support lightweight connectivity, while some other CSG cells may not support lightweight connectivity. For example, a cell belonging to an anchor base station may support a light connection function, and a PLMN of a cell belonging to an anchor base station and a cell belonging to another PLMN (an PLMN id of an anchor base station cell, equivalent PLMN id and a cell belonging to another PLMN id) may not support lightweight connectivity. In another example, some base stations in a E-UTRAN may support a light connection, while other base stations may not support a light connection. Other RATs (eg UTRAN, GERAN, 2G, 3G, etc.) may not support lightweight connections. Other examples may support lightweight connections within E-UTRAN and other RATs (e.g., UTRAN, GERAN, 2G, 3G, etc.) may not support lightweight connections. In another example, when an inter-RAT reselection is performed according to movement of a cell or a terminal and a terminal selects another PLMN according to roaming, a terminal configured as a light connection can move to a cell that does not support a light connection.

In such a case, a terminal having a light connection may be difficult to perform communication. For example, since an S1 connection between an anchor base station and a core network entity is maintained for a terminal having a light connection, it may be difficult to receive the downlink data when the downlink data is transmitted to the terminal. The following examples may be used individually or in any combination.

1) From AS to RRC idle state, Triggered  Way

For one of the reasons described above or for any reason, a terminal with a light connection may reselect a cell that does not support a light connection (reselected to camp on), causing the lightly connected terminal to transition to the idle state . A light connection state can be considered a sub state of the connection state or another state that is different from the connection state. In the conventional connection state terminal, the connection state is maintained and the handover is performed in order to minimize the service interruption due to the cell change. However, the lightly connected state terminal can use the same mechanism as the selly selection mechanism of RRC IDLE in a state of suspending data transmission when cell change is performed while data transmission is suspended. Thus, it may be desirable to transition to a RRC idle state for a terminal with a light connection.

For example, the light connection terminal can recognize that the cell is out of the paging area configured by the anchor base station based on the information broadcasted through the reselected cell or information received in synchronization through the cell. In another example, a light connection terminal may determine whether the corresponding cell supports a light connection based on information (eg, system information) broadcasted through a reselected cell or information received in synchronization with the cell .

If the light reselected cell is a cell that does not support lightweight connectivity, the terminal may transition from lightweight to RRC idle mode.

For example, the terminal may perform one or more of the following operations.

- The terminal resets the MAC.

- The terminal discards / removes the stored terminal AS context.

- The terminal instructs the upper layer. Alternatively, the terminal notifies the upper layer together with the cause. The information indicated by the terminal to the upper layer may be one of information released from the RRC connection or information indicating that the light connection terminal reselects a cell which does not support the light connection function or the terminal instructs the tracking area update to be performed.

- If the timer started in accordance with the restart procedure or RAN paging update is in operation, stop it.

The UE releases all radio resources including RLC entity, MAC configuration and release of the associated PDCP entity for all configured radio bearers.

- The UE transitions to the ECM-IDLE state. Or the NAS transitions to the ECM-IDLE state.

In another example, if an MO signal or MO data occurs while a light connection terminal performs cell selection, the AS of the light connection terminal may attempt to request a connection resume. If a light connection terminal reselects a cell that is not lightly connected (data is camped on by reselecting) while the data is buffered in the AS of the terminal, the light connection terminal can return the data to an upper layer .

In another example, if an MO signal or MO data occurs while a light connection terminal performs cell selection, the AS of the light connection terminal may attempt to request a connection resume. If a light connection terminal reselects a cell that does not support a light connection (data is camped on by reselecting) while the data is buffered in the terminal's AS, the light connection terminal keeps the data from the upper layer You can associate / map / forward to the AS when the connection mode transitions.

2) How to transfer system information to NAS.

For one of the reasons described above, or for any reason, a terminal with a light connection can reselect a cell that does not support a light connection. Alternatively, the terminal can reselect and camp on.

For example, the light connection terminal can recognize that the cell is out of the paging area configured by the anchor base station based on the information broadcasted through the reselected cell or information received in synchronization through the cell. In another example, a light connection terminal can know whether the corresponding cell supports a light connection function based on information broadcasted through a reselected cell or information received synchronously through the corresponding cell. The AS of the terminal can forward the system information to the NAS. This may be information received in synchronization with the broadcast channel, or may be information received by the terminal in response to a request from the base station.

For example, an AS (or terminal) of a lightly connected terminal may forward NAS system information to the NAS. In another example, the AS (or terminal) of the lightly connected terminal may report the available PLMNs information to the NAS together with the associated RAT information.

As another example, the AS (or the terminal) of the light connection terminal can report registration area information (e.g., tracking area code, TAI, tracking area / routing area / location area related code, identification information, etc.) to the NAS.

As another example, a NAS may be alerted when a selly selection causes a change in the system information associated with the NAS.

As another example, the AS (or terminal) of the lightly connected terminal may instruct the NAS to change the NAS system information.

As another example, the NAS that has received the system information can transition the terminal state to the ECM-IDLE state. For example, a NAS receiving specific system information may transition from an ECM-CONNECTED state to an ECM-IDLE state.

3) Network registration / area registration method.

If, for any reason, or for any reason, a terminal with a light connection reselects a cell that does not support a light connection (reselects to camp on), the lightly connected terminal may perform network registration / domain registration can do.

For example, the light connection terminal can recognize that the cell is out of the paging area configured by the anchor base station based on the information broadcasted through the reselected cell or information received in synchronization through the cell. In another example, a light connection terminal can know whether the corresponding cell supports a light connection function based on information broadcasted through a reselected cell or information received synchronously through the corresponding cell.

For example, the light connection terminal may transition to the idle state and then transition to the connection state to perform the network registration / area registration.

In another example, the lightly connected terminal may transition to a connected state to perform network registration / domain registration.

In another example, if the lightly connected terminal has selected / reselected a different RAT (UTRAN, GERAN, 2G, 3G, etc.) from the previous cell (or anchor base station), the terminal may be allowed to perform network registration / domain registration. This will be described below.

The AS (or terminal) of the terminal transmits the received system information to the NAS. The NAS (or terminal) of the terminal detects that the terminal has entered a location area not included in the list of registration area information registered in the network. The NAS (or terminal) of the terminal instructs the AS of the terminal to establish an RRC connection for network registration / area registration. The AS (or terminal) of the terminal discards the stored AS context. For example, if the cell reselected by the light connection terminal is a cell that does not support the light connection feature (recognizing this), the terminal may cause the stored terminal AS context to be discarded. In another example, when the AS (or the terminal) of the terminal transmits the received system information to the NAS, the terminal may cause the stored terminal AS context to be discarded. In another example, the AS (or the terminal) of the terminal may cause the stored terminal AS context to be discarded when the upper layer instructs to establish an RRC connection.

The terminal sends a location registration (e.g., a routing area update) request message to the current core network entity (e.g., SGSN) via another RAT base station (e.g., RNC / BSS etc.). The location registration message may include information that can identify the UE from the previous core network entity (e.g., MME) of the terminal and the current core network entity. For example, the core network entity can request a terminal context from a previous core network entity using this information. As another example, the current core network entity may use this information to direct the previous core network entity to release the S1 connection maintained by the previous core network entity. It may contain information to indicate this, or it may release it if the S1 connection is maintained in the MME. As another example, the current core network entity may send a context acknowledgment message to the previous core network entity. If an MME has an S1 connection with an anchor eNB, the MME can release a S1 Release command message (e.g., a UE Context Release Command message) to the anchor base station to release the S1 connection. Upon receipt of the S1 Release command message, the anchor base station may terminate all associated signaling and user data transmission resources. And may reply to the MME with an S1 Release Complete message (e.g. UE Context Release Complete message).

In another example, if the terminal has selected / reselected a cell that does not support a light connection in the same RAT (LTE or New RAT), the terminal may be allowed to perform a network area registration / tracking area update. This will be described below.

For example, the AS (or terminal) of the terminal transmits the received system information to the NAS. The NAS (or terminal) of the terminal detects that the terminal has entered a location area not included in the list of registration area information registered in the network. The NAS (or terminal) of the terminal instructs the AS of the terminal to establish an RRC connection for network registration / area registration. The AS (or terminal) of the terminal discards the stored AS context. For example, if the light connection terminal recognizes that the reselected cell is a cell that does not support the light connection function, the terminal may discard the stored terminal AS context. In another example, when the AS (or the terminal) of the terminal transmits the received system information to the NAS, the terminal may cause the stored terminal AS context to be discarded. As another example, when the AS (or the terminal) of the terminal instructs the upper layer to set up the RRC connection, it may discard the stored terminal AS context.

In another example, the AS (or the terminal) of the terminal can recognize that the corresponding cell is out of the paging area configured by the anchor base station through the received system information, or that the corresponding cell does not support the light connection function. For example, the AS (or terminal) of the terminal transmits the received system information to the NAS. The NAS (or terminal) of the terminal detects that the terminal has entered a location area not included in the list of registration area information registered in the network. The NAS (or terminal) of the terminal instructs the AS of the terminal to establish an RRC connection for network registration / area registration. The AS (or terminal) of the terminal discards the stored AS context. For example, if the light connection terminal recognizes that the reselected cell is a cell that does not support the light connection function, the terminal may discard the stored terminal AS context. In another example, when the AS (or the terminal) of the terminal transmits the received system information to the NAS, the terminal may cause the stored terminal AS context to be discarded. As another example, when the AS (or the terminal) of the terminal instructs the upper layer to set up the RRC connection, it may discard the stored terminal AS context.

In another example, the UE transmits a location registration (e.g., a tracking area update) request message to a current core network entity (e.g., MME) through a base station (e.g., an eNB in the case of an LTE terminal) of the same RAT. The location registration message may include information for identifying a UE in a previous core network entity (e.g., old MME) and a current core network entity (new MME). For example, the core network entity can request a terminal context from a previous core network entity using this information. As another example, the current core network entity may use this information to direct the previous core network entity to release the S1 connection maintained by the previous core network entity. It may contain information to indicate this, or it may release it if the S1 connection is maintained in the MME. As another example, the current core network entity may send a context acknowledgment message to the previous core network entity. If an MME has an S1 connection with an anchor eNB, the MME can release a S1 Release command message (e.g., a UE Context Release Command message) to the anchor base station to release the S1 connection. Upon receipt of the S1 Release command message, the anchor base station may terminate all associated signaling and user data transmission resources. Then, the MME can respond to the S1 Release Complete message (e.g., the UE Context Release Complete message).

In another example, the UE transmits a location registration (e.g., a tracking area update) request message to a current core network entity (e.g., MME) through a base station (e.g., an eNB in the case of an LTE terminal) of the same RAT. The location registration message may include information for identifying a UE in a previous core network entity (e.g., old MME) and a current core network entity (new MME). If the current core network entity is the same as the previous core network entity, if the S1 connection with the anchor base station (anchor eNB) is maintained in the MME, the MME transmits an S1 Release command message (for example, UE Context Release Command message) to the anchor base station To disconnect the previous S1 connection. Upon receipt of the S1 Release command message, the anchor base station may terminate all associated signaling and user data transmission resources. And may respond to the MME with an S1 Release Complete message (e.g., a UE Context Release Complete message).

For example, cells that do not support light connections may be divided into cells that support light connections and other tracking areas.

Another example of this is that cells that do not support lightweight connections can be organized into cells that support lightweight connections and different TAIs lists.

As another example of this, one tracking area can be configured not to include cells that do not support light connections and cells that support light connections at the same time.

As another example, one TAI list can be configured not to include cells that do not support lightweight connections and cells that support lightweight connections.

As another example of this, the paging area of the light connection terminal can be configured to be the same as the tracking area. For example, if a lightly connected terminal leaves the paging area, a tracking area update is triggered. Accordingly, the S1 connection between the MME and the anchor base station can be released.

4) Light connection function in cell Whether to support  Information to direct Broadcast  How to.

For one of the reasons described above, or for any reason, a terminal with a light connection can reselect a cell that does not support a light connection. Alternatively, the terminal can reselect and camp on.

When a mobile terminal configured with a light connection moves through a cell change, if an anchor base station moves to a cell included in a paging area configured to be terminal specific (or cell specific) to a terminal configured with a light connection, (Implicitly).

However, when a mobile terminal having a light connection moves to a different cell, if an anchor base station moves out of a cell included in a paging area configured to be terminal specific (or cell specific) to a terminal configured with a light connection, It may support lightweight connectivity or may not support lightweight connectivity.

The base station can transmit information (or any information related to the light connection function) to indicate that it supports the light connection function (or a specific function on the light connection function) through the system information.

For example, when a terminal having a light connection moves a cell (when an anchor base station moves out of a cell included in a paging area configured to be terminal-specific (or cell-specific) to a terminal configured with a light connection) If the light connection function (or light connection function related information) is broadcast through the system information, the terminal can start updating the paging area. For example, it is possible to explicitly define and broadcast information indicating a light connection function support. Another example is a system related to light connection function (RAN paging, X2 paging, light connection status, paging update, network notification, terminal context storage / extraction, support for cell selection based mobility support, RRC connection resume etc.) Information) to be implicitly known.

As another example, when a mobile terminal configured with a light connection moves a cell, if an anchor base station moves out of a cell included in a paging area configured to be terminal-specific (or cell-specific) to a terminal configured with a light connection, If the function support (or light connection function related information) is not broadcast through the system information, the terminal can perform one or more of the operations of the embodiments of the present invention. For example, the UE may transition to the RRC idle state.

5) Does not support light connections Selly selection  City AS Contact  A method for indicating a holding time.

Selly selection may continue to occur due to the movement of the light connection terminal. If a lightly connected terminal reselects a cell that does not support a light connection (reselects to camp on), it may reselect the cell that supports the light connection again within a certain period of time. If a light connection terminal reselects a cell that does not support a light connection, unnecessary signaling may be added if it immediately removes the stored terminal context or transitions the terminal to the IDLE state. To mitigate this, the base station may indicate a particular timer.

If a light connection terminal initiates a timer that reselects a cell that does not support a light connection. If the cell does not reselect a cell that supports a light connection until the timer is completed, the stored terminal context can be removed or the terminal can be transitioned to the IDLE state.

If a cell that supports a light connection is reselected before the timer is completed, the timer is stopped or restarted.

6) Timer or Specific instruction information  Through AS Context discard  Way.

When the terminal is configured in a light connection state by the anchor base station, if the terminal does not perform data transmission / reception for a long time, the anchor base station may desire to remove the AS context of the corresponding terminal. In order to instruct the anchor base station to operate in the idle mode with the light connection, the anchor base station pauses the terminal configured with the light connection so that the light connection state terminal performs the RRC connection resumption / setup procedure to transition the terminal to the connection state And instruct the transition to the back-idle mode.

In order to simplify such a complex operation, an anchor base station may configure a timer for allowing a corresponding terminal to transition to an idle mode after a specific time when a light connection state is established in the terminal. The terminal or the anchor base station may perform one or more of the following operations when the timer expires.

-RRC Transit to IDLE state.

-MAC is reset.

- Discard / remove stored terminal AS context.

- Release all radio resources including RLC entity, MAC configuration and release of associated PDCP entity for all configured radio bearers.

- Indicate to the higher layer.

- The UE transitions to the ECM-IDLE state. Or the NAS of the terminal transits to the ECM-IDLE state. The base station triggers the release of the S1 connection.

As another example for simplifying such a complex operation, a base station that performs paging according to a paging request initiated by an anchor base station or an anchor base station may configure information for instructing a corresponding terminal to transit to an idle mode on a paging message.

When the terminal receives the information, the terminal can perform one or more of the following operations.

-RRC Transit to IDLE state.

-MAC is reset.

- Discard / remove stored terminal AS context.

- Release all radio resources including RLC entity, MAC configuration and release of associated PDCP entity for all configured radio bearers.

- Indicate to the higher layer.

- The UE transitions to the ECM-IDLE state. Or the NAS of the terminal transits to the ECM-IDLE state. The base station triggers the release of the S1 connection.

As another example for simplifying such a complicated operation, when the UE requests the RRC connection resumption according to the paging request initiated by the anchor base station or the anchor base station, information for instructing the UE to transit to the idle mode is configured on the response RRC message .

When the terminal receives the information, the terminal can perform one or more of the following operations.

-RRC Transit to IDLE state.

-MAC is reset.

- Discard / remove stored terminal AS context.

- Release all radio resources including RLC entity, MAC configuration and release of associated PDCP entity for all configured radio bearers.

- Indicate to the higher layer.

- The UE transitions to the ECM-IDLE state. Or the NAS of the terminal transits to the ECM-IDLE state. The base station triggers the release of the S1 connection.

Alternatively, the base station can increase the likelihood of performing cell-cell reselection that supports a lightweight connection, with the cell-selection priority of the cell supporting the light-connection state as the highest priority.

Alternatively, the AS context may be discarded when the originating NAS signaling or MO data is initiated. If the lightly connected terminal initiates NAS signaling or MO data from the upper layer for any reason (indicating RRC connection establishment), the terminal's AS may initiate the RRC connection establishment procedure without initiating the RRC connection resumption request. In this case, the terminal can discard the stored terminal context.

Hereinafter, a non-access stratum (NAS) state and a light connection state transition method of a terminal will be described. The following methods may be used individually or in combination.

For example, a NAS state and a light connection state transition method of a terminal for a light connection state terminal can use the following methods individually or in combination.

- When NAS recognizes a light connection status (terminal NAS: ECM-CONNECTED, terminal AS: RRC-IDLE)

For example, when a light connection is established to the terminal through RRC signaling, the terminal's RRC can instruct it to the NAS. In this case, the terminal's NAS can consider the terminal as ECM-CONNECTED but in the RRC-IDLE state. Or the NAS of the terminal is lightly connected. The NAS of the terminal maintains the NAS context.

When the terminal is triggered by the NAS signaling or MO data, the NAS / higher layer may instruct the RRC to transition to the connected state via the maintained / stored AS context.

In the Suspend / Resume procedure for the conventional NB-IoT terminal, the RRC Connection Resume Request is initiated by an instruction of the upper layer. In resuming the RRC connection at the instruction of the upper layer, the resume cause (resumeCause-r13) included in the RRC Connection Resume Request message has one of the following setup causes (EstablishmentCause-NB-r13).

ExceptionData, spare4, spare3, spare2, spare1} {mt-Access, mo-Signaling, mo-Data, mo-ExceptionData}

If it is intended to transit a lightly connected terminal to a connected state, the corresponding base station must recognize the cause to extract the terminal AS context from the anchor base station. For example, the upper layer and / or the RRC Connection Resume Request message may include a spare value of a setting cause (EstablishmentCause-NB-r13) for indicating a resume cause (resumeCause-r13) Or the like.

As another example for distinguishing and instructing the upper layer and / or the RRC Connection Resume Request message, the upper layer and / or the RRC Connection Resume Request message may specify the indication information for distinguishing the upper layer and / or the RRC Connection Resume Request message by defining a different field from the resume cause (resumeCause-r13). In this case, it is assumed that the cause of the resumption is mt-Access, mo-Signaling, mo-Data, mo-ExceptionData and that the resumption request message is triggered to transition the light connection terminal into the connection state. It is instructed to extract the context. As another example for distinguishing and instructing the upper layer and / or the RRC Connection Resume Request message, the upper layer and / or the RRC Connection Resume Request message includes a setting cause on the existing resume cause (resumeCause-r13) It is possible to designate and direct a field indicating that it is for instructing to extract the terminal AS context from the anchor base station.

- When NAS recognizes the light connection status (terminal NAS: ECM-IDLE, terminal AS: RRC-IDLE)

As another example, when a light connection is established to the terminal through RRC signaling, the terminal's RRC may indicate (notify) it to the NAS. For example, the RRC can pass information to the NAS indicating a light connection status. In this case, the NAS of the terminal can consider the terminal as an ECM-IDLE and an RRC-IDLE state. It can be seen that the terminal is in a light connection state. Or the NAS of the terminal is lightly connected.

The NAS of the terminal may perform one or more of the following operations.

- The terminal maintains the NAS context.

- The terminal stores the NAS context.

- The terminal releases the NAS context but stores it. When NAS signaling or MO data is triggered in the terminal, it is reused / resumed / recovered / maintained / invoked.

- The terminal suspends the NAS context. When NAS signaling or MO data is triggered in the terminal, it is reused / resumed / recovered / maintained / invoked.

When the MS signaling or MO data is triggered, the MS / layer transmits it to the RRC. The RRC may be allowed to transition to a connected state via a maintained / stored AS context.

In the Suspend / Resume procedure for the conventional NB-IoT terminal, the RRC Connection Resume Request is initiated by an instruction of the upper layer. In resuming the RRC connection at the instruction of the upper layer, the resume cause (resumeCause-r13) included in the RRC Connection Resume Request message has one of the following setup causes (EstablishmentCause-NB-r13).

ExceptionData, spare4, spare3, spare2, spare1} {mt-Access, mo-Signaling, mo-Data, mo-ExceptionData}

If it is intended to transit a lightly connected terminal to a connected state, the corresponding base station must recognize the cause to extract the terminal AS context from the anchor base station. For example, the upper layer and / or the RRC Connection Resume Request message may include a spare value of a setting cause (EstablishmentCause-NB-r13) for indicating a resume cause (resumeCause-r13) Or the like.

As another example for distinguishing and instructing the upper layer and / or the RRC Connection Resume Request message, the upper layer and / or the RRC Connection Resume Request message may specify the indication information for distinguishing the upper layer and / or the RRC Connection Resume Request message by defining a different field from the resume cause (resumeCause-r13). In this case, it is assumed that the cause of the resumption is mt-Access, mo-Signaling, mo-Data, mo-ExceptionData and that the resumption request message is triggered to transition the light connection terminal into the connection state. It is instructed to extract the context. As another example for distinguishing and instructing the upper layer and / or the RRC Connection Resume Request message, the upper layer and / or the RRC Connection Resume Request message includes a setting cause on the existing resume cause (resumeCause-r13) It is possible to designate and direct a field indicating that it is for instructing to extract the terminal AS context from the anchor base station.

- If the NAS does not recognize the light connection status (terminal NAS: ECM-CONNECTED, terminal AS: RRC-IDLE)

As another example, when a light connection is established to the terminal through RRC signaling, the terminal's RRC may not indicate (notify) it to the NAS. In this case, the NAS of the terminal considers the terminal to be in the ECM-CONNECTED state. The AS (or RRC) of the terminal can be considered as the RRC-IDLE state. It can be seen that the terminal (or AS or RRC of the terminal) is in a light connection state. When the NAS signaling or MO data is triggered, the NAS / higher layer forwards it to the corresponding SRB or DRB. Once the data is transferred to the SRB / DRB, the RRC may transition to the connected state via the maintained / stored AS context.

Through the operations described above, when a terminal having a light connection performs cell selection, communication between the terminal and the network can be efficiently performed based on the information of the corresponding cell.

Hereinafter, configurations of a terminal and a base station capable of performing a part or all of the operations described above will be described once more with reference to the drawings.

5 is a diagram for explaining a terminal configuration according to an embodiment.

5, the UE 500 includes a receiving unit 530 that receives indication information indicating a state change from a base station to a specific RRC state, and a receiving unit 530 that configures the connection state of the UE to a specific RRC state based on the indication information, And a control unit 510 for performing a cell re-selection operation according to movement of the UE. The control unit 510 includes information on whether to initiate an RRC restart procedure, system information of a selected cell according to a cell re- The connection state of the terminal can be changed to the RRC idle state.

For example, the specific RRC state is distinguished from the RRC connection state and the RRC idle state, and stores the terminal context of the terminal 500. The RRC idle state is a write connection state or an RRC active state ) State.

The transmitting unit 520 can transmit information to the base station that the terminal 500 can support a specific RRC state. For example, the transmitter 520 can transmit information indicating that the corresponding terminal 500 can configure a specific RRC state to the base station through the terminal capability.

On the other hand, when the control unit 510 receives the instruction information for instructing to change the connection state from the base station to the specific RRC state, the control unit 510 can change the connection state of the terminal 500 to the specific RRC state based on the instruction information. For example, the controller 510 may change the setting of the terminal to change from the RRC connection state to the specific RRC state. In another example, the control unit 510 may store a terminal context, support RAN initiation paging, and suspend all SRBs and DRBs to configure a particular RRC state.

Also, the terminal 500 can perform movement in a specific RRC state. For example, the control unit 510 of the terminal 500 configured in a specific RRC state can perform a cell re-selection operation according to movement. When the radio quality of a cell constituting a specific RRC state drops, the control unit 510 can perform a cell re-selection operation in consideration of the state of another cell.

In addition, the control unit 510 may change the connection state of the terminal from the specific RRC state to the RRC idle state or the RRC connected state according to the movement of the terminal 500.

For example, the control unit 510 may change the connection state of the terminal to the RRC idle state when the system information does not include information supporting the specific RRC state. Specifically, the receiving unit 530 receives the system information of the reselected cell through the cell re-selection operation, and the control unit 510 checks the received system information to check whether the reselected cell supports the specific RRC state have. If the reselected cell does not support a specific RRC state, the control unit 510 may change the specific RRC state to the RRC idle state. This provides the effect of eliminating the connection state ambiguity of the terminal that may occur, since the reselected cell does not support a specific RRC state.

As another example, if the radio access technology of the selected cell is different from the cell constituting the specific RRC state according to the reselection operation, the control unit 510 may change the connection state of the terminal 500 to the RRC idle state . Specifically, the control unit 510 confirms the radio access technology of the reselected cell, and can change the connection state of the mobile station to the RRC idle state when the radio access technology is changed from the previously accessed cell. For example, the control unit 510 determines whether a cell in which a connection state is established in a specific RRC state uses an E-UTRAN-based radio access technology, and a cell reselected according to movement uses another radio access technology such as WiFi or 3G The connection state can be changed to the RRC idle state.

As another example, when the terminal 500 starts the RRC resumption procedure for transition to the RRC connection state before the cell reselection operation, the control unit 510 changes the connection state of the terminal 500 to the RRC idle state . Specifically, the controller 510 may perform an RRC resume procedure to perform a transition from a specific RRC state to an RRC connected state. For example, when originated data (MO data) is generated in a terminal 500 in a specific RRC state, the controller 510 may perform an RRC resume procedure to change the state of the terminal 500 to the RRC connected state. However, when origination data is generated in the terminal 500 in the specific RRC state or when the terminal 500 initiating the RRC resume procedure reselects the cell according to the movement, the controller 510 sets the connection state to the RRC idle state Can be changed.

On the other hand, when the terminal 500 is out of the RAN start paging area, the controller 510 can update the paging area when the system information includes information supporting a specific RRC state. For example, the terminal 500 may move out of the RAN start paging area of the base station that configured the specific RRC state according to the movement. In this case, the control unit 510 confirms the system information of the reselected cell and checks whether the system information includes information indicating the support of a specific RRC state. If the reselected cell supports a specific RRC state, the control unit 510 can update the paging area. If necessary, the control unit 510 can maintain a specific RRC state.

In addition, the receiver 530 receives downlink control information, data, and messages from the base station through the corresponding channel. In addition, the controller 510 controls the overall operation of the terminal 500 to change the connection state of the terminal according to the movement of the terminal in the specific RRC state. The transmitter 520 transmits uplink control information, data, and a message to the base station through the corresponding channel.

6 is a view for explaining a base station configuration according to an embodiment.

Referring to FIG. 6, the BS 600 transmits information on whether a specific RRC state of a cell provided by a corresponding BS is supported through the system information, and changes the state of the MS to a specific RRC state A transmission unit 620 for transmitting the instruction information to be instructed, and a controller 610 for configuring the connection state of the terminal into a specific RRC state.

For example, a specific RRC state is distinguished from an RRC connection state and an RRC idle state. The terminal context is stored, and a light connection state supporting RAN start paging operation or an RRC active state it means.

Meanwhile, the transmitter 620 may transmit information indicating whether a cell provided by the corresponding base station supports a specific RRC state, through the system information. The UE can receive the system information and confirm that the cell supports a specific RRC connection state.

In addition, the transmitter 620 can transmit the indication information through the RRC message. In this case, the receiver 630 may receive the terminal capability information including information on whether the terminal supports a specific RRC state, and may recognize that the terminal supports a specific RRC state.

The controller 610 may change the connection state of the terminal to a specific RRC state. For example, the controller 610 may change the setting so that the corresponding terminal changes from the RRC connection state to the specific RRC state. As another example, the controller 610 may store a terminal context, support RAN initiation paging, and suspend all SRBs and DRBs to configure a particular RRC state for that terminal.

Meanwhile, the UE can perform the movement in a specific RRC state. For example, a UE configured with a specific RRC state can perform a cell reselection operation according to movement. When the radio quality of a cell constituting a specific RRC state drops, the UE can perform a cell re-selection operation considering the state of another cell.

The UE having the specific RRC state sets the connection state of the UE to the RRC idle state based on at least one of information about whether to start the RRC resumption procedure, system information of the selected cell according to the cell re-selection operation, Can be changed.

For example, the UE may change the connection state of the UE to the RRC idle state when the system information does not include information supporting the specific RRC state. Specifically, the UE can receive the system information of the reselected cell through the cell re-selection operation and check the received system information to confirm that the reselected cell supports the specific RRC state. If the reselected cell does not support a specific RRC state, the terminal may change the specific RRC state to the RRC idle state.

As another example, if the radio access technology of the selected cell is different from the cell constituting the specific RRC state according to the reselection operation, the terminal may change the connection state of the terminal to the RRC idle state. Specifically, the UE confirms the radio access technology of the reselected cell, and can change the connection state of the UE to the RRC idle state when the radio access technology is changed from the previously accessed cell. For example, when a cell in which a UE configures a connection state in a specific RRC state uses an E-UTRAN-based radio access technology and a cell reselected according to movement uses another radio access technology such as WiFi or 3G The terminal may change the connection state to the RRC idle state.

As another example, the UE may change the connection state of the UE to the RRC idle state when the UE initiates the RRC resumption procedure for transition to the RRC connection state before the cell reselection operation. Specifically, the UE may perform an RRC resume procedure to perform a transition from a specific RRC state to an RRC connected state. For example, when origination data (MO data) is generated in a terminal in a specific RRC state, the terminal may change the state of the terminal to the RRC connected state by performing an RRC resume procedure. However, when origination data is generated in a terminal in a specific RRC state or a terminal initiated an RRC resume procedure reselects a cell according to the movement, the terminal can change the connection state to the RRC idle state.

Meanwhile, the UE can perform the paging area update when the UE is out of the RAN start paging area and the system information includes information supporting a specific RRC state. For example, the UE may move out of the RAN start paging area of the base station that configured the specific RRC state according to the movement. In this case, the UE confirms the system information of the reselected cell and checks whether the system information includes information indicating the support of a specific RRC state. If the reselected cell supports a specific RRC state, the terminal can update the paging area. If necessary, the UE can maintain a specific RRC state.

In addition, the controller 610 controls the overall RRC state configuration of the base station and the overall operation of the base station 600 for the connection state transition operation and the paging message processing according to the movement of the terminal, which are necessary for performing the above-described embodiments.

The transmitting unit 620 and the receiving unit 630 are used to transmit and receive signals, messages, and data necessary for performing the above-described embodiments to and from the terminal.

The standard content or standard documents referred to in the above-mentioned embodiments constitute a part of this specification, for the sake of simplicity of description of the specification. Therefore, it is to be understood that the content of the above standard content and portions of the standard documents are added to or contained in the scope of the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (20)

A method for a terminal to change a connection state,
Receiving instruction information indicating a state change from a base station to a specific RRC state;
Configuring the connection state of the terminal to the specific RRC state based on the instruction information, and performing a cell re-selection operation according to the movement of the terminal;
A connection state change for changing a connection state of the UE to an RRC idle state based on at least one of information about whether to initiate an RRC restart procedure, system information of a cell selected according to the cell re-selection operation, ≪ / RTI >
The specific RRC state may include:
The RRC connection state and the RRC id state. The method according to claim 1,
The specific RRC state may include:
Wherein the terminal context of the terminal is stored in a light connection state supporting RAN initiation paging operation or an RRC active state. The method according to claim 1,
The connection state changing step may include:
And changing the connection state of the terminal to the RRC idle state when the system information does not include information supporting the specific RRC state. The method according to claim 1,
The connection state changing step may include:
And changing the connection state of the UE to the RRC idle state when the radio access technology of the selected cell is different from the cell constituting the specific RRC state according to the reselection operation. The method according to claim 1,
The connection state changing step may include:
And changing the connection state of the UE to the RRC idle state when the UE starts the RRC resumption procedure for transition to the RRC connected state before the cell re-selection operation. The method according to claim 1,
The connection state changing step may include:
Wherein when the UE is out of the RAN start paging area, the paging area update is performed when the system information includes information supporting the specific RRC state. A method of controlling a connection state change of a terminal by a base station,
Transmitting information on whether a particular RRC state of the cell provided by the corresponding base station is supported through the system information;
Transmitting indication information indicating a state change to a specific RRC state to a terminal in a cell provided by the base station; And
And configuring the connection state of the UE to the specific RRC state,
The specific RRC state may include:
The RRC connection state and the RRC id state. 8. The method of claim 7,
The specific RRC state may include:
Wherein the terminal context of the terminal is stored in a light connection state supporting RAN initiation paging operation or an RRC active state. 8. The method of claim 7,
In the specific RRC state,
The cell reselection operation is performed according to the movement of the terminal and the connection state is changed to the RRC idle state when the system information of the cell selected by the cell reselection operation includes information supporting the specific RRC state. Lt; / RTI > 8. The method of claim 7,
In the specific RRC state,
When a radio access technology of a cell selected by the cell re-selection operation is different from a cell provided by the base station, a connection state of the UE is referred to as the RRC idle State. ≪ / RTI > In a terminal that changes a connection state,
A receiving unit for receiving indication information indicating a state change from a base station to a specific RRC state; And
And a control unit configured to configure a connection state of the terminal to the specific RRC state based on the instruction information and to perform a cell re-selection operation according to the movement of the terminal,
Wherein,
Changing a connection state of the UE to an RRC idle state based on at least one of information on whether to initiate an RRC resumption procedure, system information of a cell selected according to the cell re-selection operation, and radio access technology information,
The specific RRC state may include:
The RRC connection state, and the RRC id state. 12. The method of claim 11,
The specific RRC state may include:
Wherein the terminal context is a write connection state in which the terminal context is supported and a RAN start paging operation, or an RRC active state. 12. The method of claim 11,
Wherein,
And changes the connection state of the terminal to the RRC idle state when the system information does not include information supporting the specific RRC state. 12. The method of claim 11,
Wherein,
And changes the connection state of the UE to the RRC idle state when the radio access technology of the selected cell is different from the cell configuring the specific RRC state according to the reselection operation. 12. The method of claim 11,
Wherein,
And changes the connection state of the UE to the RRC idle state when the UE starts the RRC resumption procedure for transition to the RRC connected state before the cell re-selection operation. 12. The method of claim 11,
Wherein,
Wherein the terminal performs the paging area update when the UE is out of the RAN initiation paging area and the system information includes information supporting the specific RRC state. A base station for controlling connection state change of a terminal,
Transmits information on whether or not the specific RRC state of the cell provided by the corresponding base station is supported through the system information,
A transmitter for transmitting indication information indicating a state change to a specific RRC state to a terminal in a cell provided by the base station; And
And a controller configured to configure a connection state of the UE to the specific RRC state,
The specific RRC state may include:
The RRC connection state, and the RRC idle state. 18. The method of claim 17,
The specific RRC state may include:
Wherein the terminal context of the mobile station is a write connection state supporting an RAN initiation paging operation or an RRC active state. 18. The method of claim 17,
In the specific RRC state,
The cell reselection operation is performed according to the movement of the terminal and the connection state is changed to the RRC idle state when the system information of the cell selected by the cell reselection operation includes information supporting the specific RRC state. . 18. The method of claim 17,
In the specific RRC state,
When a radio access technology of a cell selected by the cell re-selection operation is different from a cell provided by the base station, a connection state of the UE is referred to as the RRC idle State.

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