Patent Publication Number: US-11044776-B2

Title: Method for attempting network access from NB-IoT RAT

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2016/012835, filed on Nov. 9, 2016, which claims the benefit of U.S. Provisional Application Nos. 62/313,797, filed on Mar. 27, 2016, 62/313,800, filed on Mar. 27, 2016, 62/315,652, filed on Mar. 30, 2016, 62/315,650, filed on Mar. 30, 2016, 62/318,235, filed on Apr. 5, 2016, 62/318,233, filed on Apr. 5, 2016, 62/325,454, filed on Apr. 20, 2016, 62/325,963, Apr. 21, 2016, 62/325,979, filed on Apr. 21, 2016, 62/332,480, filed on May 6, 2016, and 62/332,478, filed on May 6, 2016, the contents of which are all hereby incorporated by reference herein in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to mobile communication. 
     Related Art 
     In 3GPP in which technical standards for mobile communication systems are established, in order to handle 4th generation communication and several related forums and new technologies, research on Long Term Evolution/System Architecture Evolution (LTE/SAE) technology has started as part of efforts to optimize and improve the performance of 3GPP technologies from the end of the year 2004. 
     SAE that has been performed based on 3GPP SA WG2 is research regarding network technology that aims to determine the structure of a network and to support mobility between heterogeneous networks in line with an LTE task of a 3GPP TSG RAN and is one of recent important standardization issues of 3GPP. SAE is a task for developing a 3GPP system into a system that supports various radio access technologies based on an IP, and the task has been carried out for the purpose of an optimized packet-based system which minimizes transmission delay with a more improved data transmission capability. 
     An Evolved Packet System (EPS) higher level reference model defined in 3GPP SA WG2 includes a non-roaming case and roaming cases having various scenarios, and for details therefor, reference can be made to 3GPP standard documents TS 23.401 and TS 23.402. A network configuration of  FIG. 1  has been briefly reconfigured from the EPS higher level reference model. 
       FIG. 1  shows the configuration of an evolved mobile communication network. 
     An Evolved Packet Core (EPC) may include various elements.  FIG. 1  illustrates a Serving Gateway (S-GW)  52 , a Packet Data Network Gateway (PDN GW)  53 , a Mobility Management Entity (MME)  51 , a Serving General Packet Radio Service (GPRS) Supporting Node (SGSN), and an enhanced Packet Data Gateway (ePDG) that correspond to some of the various elements. 
     The S-GW  52  is an element that operates at a boundary point between a Radio Access Network (RAN) and a core network and has a function of maintaining a data path between an eNodeB  22  and the PDN GW  53 . Furthermore, if a terminal (or User Equipment (UE) moves in a region in which service is provided by the eNodeB  22 , the S-GW  52  plays a role of a local mobility anchor point. That is, for mobility within an E-UTRAN (i.e., a Universal Mobile Telecommunications System (Evolved-UMTS) Terrestrial Radio Access Network defined after 3GPP release-8), packets can be routed through the S-GW  52 . Furthermore, the S-GW  52  may play a role of an anchor point for mobility with another 3GPP network (i.e., a RAN defined prior to 3GPP release-8, for example, a UTRAN or Global System for Mobile communication (GSM) (GERAN)/Enhanced Data rates for Global Evolution (EDGE) Radio Access Network). 
     The PDN GW (or P-GW)  53  corresponds to the termination point of a data interface toward a packet data network. The PDN GW  53  can support policy enforcement features, packet filtering, charging support, etc. Furthermore, the PDN GW (or P-GW)  53  can play a role of an anchor point for mobility management with a 3GPP network and a non-3GPP network (e.g., an unreliable network, such as an Interworking Wireless Local Area Network (I-WLAN), a Code Division Multiple Access (CDMA) network, or a reliable network, such as WiMax). 
     In the network configuration of  FIG. 1 , the S-GW  52  and the PDN GW  53  have been illustrated as being separate gateways, but the two gateways may be implemented in accordance with a single gateway configuration option. 
     The MME  51  is an element for performing the access of a terminal to a network connection and signaling and control functions for supporting the allocation, tracking, paging, roaming, handover, etc. of network resources. The MME  51  controls control plane functions related to subscribers and session management. The MME  51  manages numerous eNodeBs  22  and performs conventional signaling for selecting a gateway for handover to another 2G/3G networks. Furthermore, the MME  51  performs functions, such as security procedures, terminal-to-network session handling, and idle terminal location management. 
     The SGSN handles all packet data, such as a user&#39;s mobility management and authentication for different access 3GPP networks (e.g., a GPRS network and an UTRAN/GERAN). 
     The ePDG plays a role of a security node for an unreliable non-3GPP network (e.g., an I-WLAN and a Wi-Fi hotspot). 
     As described with reference to  FIG. 1 , a terminal (or UE) having an IP capability can access an IP service network (e.g., IMS), provided by a service provider (i.e., an operator), via various elements within an EPC based on non-3GPP access as well as based on 3GPP access. 
     Furthermore,  FIG. 1  shows various reference points (e.g., S1-U and S1-MME). In a 3GPP system, a conceptual link that connects two functions that are present in the different function entities of an E-UTRAN and an EPC is called a reference point. Table 1 below defines reference points shown in  FIG. 1 . In addition to the reference points shown in the example of Table 1, various reference points may be present depending on a network configuration. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 REFERENCE 
                   
               
               
                 POINT 
                 DESCRIPTION 
               
               
                   
               
             
            
               
                 S1-MME 
                 A reference point for a control plane 
               
               
                   
                 protocol between the E-UTRAN and the MME 
               
               
                 S1-U 
                 A reference point between the E-UTRAN and 
               
               
                   
                 the S-GW for path switching between eNodeBs 
               
               
                   
                 during handover and user plane tunneling per bearer 
               
               
                 S3 
                 A reference point between the MME and the SGSN 
               
               
                   
                 that provides the exchange of pieces of user and 
               
               
                   
                 bearer information for mobility between 3GPP 
               
               
                   
                 access networks in idle and/or activation state. 
               
               
                   
                 This reference point can be used intra-PLMN 
               
               
                   
                 or inter-PLMN (e.g. in the case of Inter-PLMN HO). 
               
               
                 S4 
                 A reference point between the SGW and the SGSN 
               
               
                   
                 that provides related control and mobility support 
               
               
                   
                 between the 3GPP anchor functions of a GPRS core 
               
               
                   
                 and the S-GW. Furthermore, if a direct tunnel is not 
               
               
                   
                 established, the reference point provides user plane 
               
               
                   
                 tunneling. 
               
               
                 S5 
                 A reference point that provides user plane tunneling 
               
               
                   
                 and tunnel management between the S-GW and the PDN 
               
               
                   
                 GW. The reference point is used for S-GW relocation 
               
               
                   
                 due to UE mobility and if the S-GW needs to connect to 
               
               
                   
                 a non-collocated PDN GW for required PDN 
               
               
                   
                 connectivity 
               
               
                 S11 
                 A reference point between the MME and the S-GW 
               
               
                 SGI 
                 A reference point between the PDN GW and the PDN. 
               
               
                   
                 The PDN may be a public or private PDN external to 
               
               
                   
                 an operator or may be an intra-operator PDN, e.g., 
               
               
                   
                 for theproviding of IMS services. This reference point 
               
               
                   
                 corresponds to Gi for 3GPP access. 
               
               
                   
               
            
           
         
       
     
     Among the reference points shown in  FIG. 1 , S 2   a  and S 2   b  correspond to non-3GPP interfaces. S 2   a  is a reference point providing the user plane with related control and mobility support between a PDN GW and a reliable non-3GPP access. S 2   b  is a reference point providing the user plane with mobility support and related control between a PDN GW and an ePDG. 
       FIG. 2  is an exemplary diagram showing the architecture of a common E-UTRAN and a common EPC. 
     As shown in  FIG. 2 , the eNodeB  20  can perform functions, such as routing to a gateway while RRC connection is activated, the scheduling and transmission of a paging message, the scheduling and transmission of a broadcast channel (BCH), the dynamic allocation of resources to UE in uplink and downlink, a configuration and providing for the measurement of the eNodeB  20 , control of a radio bearer, radio admission control, and connection mobility control. The EPC can perform functions, such as the generation of paging, the management of an LTE_IDLE state, the ciphering of a user plane, control of an EPS bearer, the ciphering of NAS signaling, and integrity protection. 
       FIG. 3  is an exemplary diagram showing the structure of a radio interface protocol in a control plane between UE and an eNodeB, and  FIG. 4  is another exemplary diagram showing the structure of a radio interface protocol in a control plane between UE and an eNodeB. 
     The radio interface protocol is based on a 3GPP radio access network standard. The radio interface protocol includes a physical layer, a data link layer, and a network layer horizontally, and it is divided into a user plane for the transmission of information and a control plane for the transfer of a control signal (or signaling). 
     The protocol layers may be classified into a first layer (L1), a second layer (L2), and a third layer (L3) based on three lower layers of the Open System Interconnection (OSI) reference model that is widely known in communication systems. 
     The layers of the radio protocol of the control plane shown in  FIG. 3  and the radio protocol in the user plane of  FIG. 4  are described below. 
     The physical layer PHY, that is, the first layer, provides information transfer service using physical channels. The PHY layer is connected to a Medium Access Control (MAC) layer placed in a higher layer through a transport channel, and data is transferred between the MAC layer and the PHY layer through the transport channel. Furthermore, data is transferred between different PHY layers, that is, PHY layers on the sender side and the receiver side, through the PHY layer. 
     A physical channel is made up of multiple subframes on a time axis and multiple subcarriers on a frequency axis. Here, one subframe is made up of a plurality of symbols and a plurality of subcarriers on the time axis. One subframe is made up of a plurality of resource blocks, and one resource block is made up of a plurality of symbols and a plurality of subcarriers. A Transmission Time Interval (TTI), that is, a unit time during which data is transmitted, is 1 ms corresponding to one subframe. 
     In accordance with 3GPP LTE, physical channels that are present in the physical layer of the sender side and the receiver side can be divided into a Physical Downlink Shared Channel (PDSCH) and a Physical Uplink Shared Channel (PUSCH), that is, data channels, and a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator Channel (PCFICH), a Physical Hybrid-ARQ Indicator Channel (PHICH), and a Physical Uplink Control Channel (PUCCH), that is, control channels. 
     A PCFICH that is transmitted in the first OFDM symbol of a subframe carries a Control Format Indicator (CFI) regarding the number of OFDM symbols (i.e., the size of a control region) used to send control channels within the subframe. A wireless device first receives a CFI on a PCFICH and then monitors PDCCHs. 
     Unlike a PDCCH, a PCFICH is transmitted through the fixed PCFICH resources of a subframe without using blind decoding. 
     A PHICH carries positive-acknowledgement (ACK)/negative-acknowledgement (NACK) signals for an uplink (UL) Hybrid Automatic Repeat reQuest (HARQ). ACK/NACK signals for UL data on a PUSCH that is transmitted by a wireless device are transmitted on a PHICH. 
     A Physical Broadcast Channel (PBCH) is transmitted in four former OFDM symbols of the second slot of the first subframe of a radio frame. The PBCH carries system information that is essential for a wireless device to communicate with an eNodeB, and system information transmitted through a PBCH is called a Master Information Block (MIB). In contrast, system information transmitted on a PDSCH indicated by a PDCCH is called a System Information Block (SIB). 
     A PDCCH can carry the resource allocation and transport format of a downlink-shared channel (DL-SCH), information about the resource allocation of an uplink shared channel (UL-SCH), paging information for a PCH, system information for a DL-SCH, the resource allocation of an upper layer control message transmitted on a PDSCH, such as a random access response, a set of transmit power control commands for pieces of UE within a specific UE group, and the activation of a Voice over Internet Protocol (VoIP). A plurality of PDCCHs can be transmitted within the control region, and UE can monitor a plurality of PDCCHs. A PDCCH is transmitted on one Control Channel Element (CCE) or an aggregation of multiple contiguous CCEs. A CCE is a logical allocation unit used to provide a PDCCH with a coding rate according to the state of a radio channel A CCE corresponds to a plurality of resource element groups. The format of a PDCCH and the number of bits of a possible PDCCH are determined by a relationship between the number of CCEs and a coding rate provided by CCEs. 
     Control information transmitted through a PDCCH is called Downlink Control Information (DCI). DCI can include the resource allocation of a PDSCH (also called a downlink (DL) grant)), the resource allocation of a PUSCH (also called an uplink (UL) grant), a set of transmit power control commands for pieces of UE within a specific UE group, and/or the activation of a Voice over Internet Protocol (VoIP). 
     Several layers are present in the second layer. First, a Medium Access Control (MAC) layer functions to map various logical channels to various transport channels and also plays a role of logical channel multiplexing for mapping multiple logical channels to one transport channel. The MAC layer is connected to a Radio Link Control (RLC) layer, that is, a higher layer, through a logical channel. The logical channel is basically divided into a control channel through which information of the control plane is transmitted and a traffic channel through which information of the user plane is transmitted depending on the type of transmitted information. 
     The RLC layer of the second layer functions to control a data size that is suitable for sending, by a lower layer, data received from a higher layer in a radio section by segmenting and concatenating the data. Furthermore, in order to guarantee various types of QoS required by radio bearers, the RLC layer provides three types of operation modes: a Transparent Mode (TM), an Un-acknowledged Mode (UM), and an Acknowledged Mode (AM). In particular, AM RLC performs a retransmission function through an Automatic Repeat and Request (ARQ) function for reliable data transmission. 
     The Packet Data Convergence Protocol (PDCP) layer of the second layer performs a header compression function for reducing the size of an IP packet header containing control information that is relatively large in size and unnecessary in order to efficiently send an IP packet, such as IPv4 or IPv6, in a radio section having a small bandwidth when sending the IP packet. Accordingly, transmission efficiency of the radio section can be increased because only essential information is transmitted in the header part of data. Furthermore, in an LTE system, the PDCP layer also performs a security function. The security function includes ciphering for preventing the interception of data by a third party and integrity protection for preventing the manipulation of data by a third party. 
     A Radio Resource Control (RRC) layer at the highest place of the third layer is defined only in the control plane and is responsible for control of logical channels, transport channels, and physical channels in relation to the configuration, re-configuration, and release of Radio Bearers (RBs). Here, the RB means service provided by the second layer in order to transfer data between UE and an E-UTRAN. 
     If an RRC connection is present between the RRC layer of UE and the RRC layer of a wireless network, the UE is in an RRC_CONNECTED state. If not, the UE is in an RRC_IDLE state. 
     An RRC state and an RRC connection method of UE are described below. The RRC state means whether or not the RRC layer of UE has been logically connected to the RRC layer of an E-UTRAN. If the RRC layer of UE is logically connected to the RRC layer of an E-UTRAN, it is called the RRC_CONNECTED state. If the RRC layer of UE is not logically connected to the RRC layer of an E-UTRAN, it is called the RRC_IDLE state. Since UE in the RRC_CONNECTED state has an RRC connection, an E-UTRAN can check the existence of the UE in a cell unit, and thus control the UE effectively. In contrast, if UE is in the RRC_IDLE state, an E-UTRAN cannot check the existence of the UE, and a core network is managed in a Tracking Area (TA) unit, that is, an area unit greater than a cell. That is, only the existence of UE in the RRC_IDLE state is checked in an area unit greater than a cell. In such a case, the UE needs to shift to the RRC_CONNECTED state in order to be provided with common mobile communication service, such as voice or data. Each TA is classified through Tracking Area Identity (TAI). UE can configure TAI through Tracking Area Code (TAC), that is, information broadcasted by a cell. 
     When a user first turns on the power of UE, the UE first searches for a proper cell, establishes an RRC connection in the corresponding cell, and registers information about the UE with a core network. Thereafter, the UE stays in the RRC_IDLE state. The UE in the RRC_IDLE state (re)selects a cell if necessary and checks system information or paging information. This process is called camp on. When the UE in the RRC_IDLE state needs to establish an RRC connection, the UE establishes an RRC connection with the RRC layer of an E-UTRAN through an RRC connection procedure and shifts to the RRC_CONNECTED state. A case where the UE in the RRC_IDLE state needs to establish with an RRC connection includes multiple cases. The multiple cases may include, for example, a case where UL data needs to be transmitted for a reason, such as a call attempt made by a user and a case where a response message needs to be transmitted in response to a paging message received from an E-UTRAN. 
     A Non-Access Stratum (NAS) layer placed over the RRC layer performs functions, such as session management and mobility management. 
     The NAS layer shown in  FIG. 3  is described in detail below. 
     Evolved Session Management (ESM) belonging to the NAS layer performs functions, such as the management of default bearers and the management of dedicated bearers, and ESM is responsible for control that is necessary for UE to use PS service from a network. Default bearer resources are characterized in that they are allocated by a network when UE first accesses a specific Packet Data Network (PDN) or accesses a network. Here, the network allocates an IP address available for UE so that the UE can use data service and the QoS of a default bearer. LTE supports two types of bearers: a bearer having Guaranteed Bit Rate (GBR) QoS characteristic that guarantees a specific bandwidth for the transmission and reception of data and a non-GBR bearer having the best effort QoS characteristic without guaranteeing a bandwidth. A default bearer is assigned a non-GBR bearer, and a dedicated bearer may be assigned a bearer having a GBR or non-GBR QoS characteristic. 
     In a network, a bearer assigned to UE is called an Evolved Packet Service (EPS) bearer. When assigning an EPS bearer, a network assigns one ID. This is called an EPS bearer ID. One EPS bearer has QoS characteristics of a Maximum Bit Rate (MBR) and a Guaranteed Bit Rate (GBR) or an Aggregated Maximum Bit Rate (AMBR). 
     Meanwhile, in  FIG. 3 , the RRC layer, the RLC layer, the MAC layer, and the PHY layer placed under the NAS layer are also collectively called an Access Stratum (AS). 
       FIG. 5 a    is a flowchart illustrating a random access process in 3GPP LTE. 
     The random access process is used for UE  10  to obtain UL synchronization with a base station, that is, an eNodeB  20 , or to be assigned UL radio resources. 
     The UE  10  receives a root index and a physical random access channel (PRACH) configuration index from the eNodeB  20 . 64 candidate random access preambles defined by a Zadoff-Chu (ZC) sequence are present in each cell. The root index is a logical index that is used for the UE to generate the 64 candidate random access preambles. 
     The transmission of a random access preamble is limited to specific time and frequency resources in each cell. The PRACH configuration index indicates a specific subframe on which a random access preamble can be transmitted and a preamble format. 
     The UE  10  sends a randomly selected random access preamble to the eNodeB  20 . Here, the UE  10  selects one of the 64 candidate random access preambles. Furthermore, the UE selects a subframe corresponding to the PRACH configuration index. The UE  10  sends the selected random access preamble in the selected subframe. 
     The eNodeB  20  that has received the random access preamble sends a Random Access Response (RAR) to the UE  10 . The random access response is detected in two steps. First, the UE  10  detects a PDCCH masked with a random access-RNTI (RA-RNTI). The UE  10  receives a random access response within a Medium Access Control (MAC) Protocol Data Unit (PDU) on a PDSCH that is indicated by the detected PDCCH. 
       FIG. 5 b    illustrates a connection process in a radio resource control (RRC) layer. 
       FIG. 5 b    shows an RRC state depending on whether there is an RRC connection. The RRC state denotes whether the entity of the RRC layer of UE  10  is in logical connection with the entity of the RRC layer of eNodeB  20 , and if yes, it is referred to as RRC connected state, and if no as RRC idle state. 
     In the connected state, UE  10  has an RRC connection, and thus, the E-UTRAN may grasp the presence of the UE on a cell basis and may thus effectively control UE  10 . In contrast, UE  10  in the idle state cannot grasp eNodeB  20  and is managed by a core network on the basis of a tracking area that is larger than a cell. The tracking area is a set of cells. That is, UE  10  in the idle state is grasped for its presence only on a larger area basis, and the UE should switch to the connected state to receive a typical mobile communication service such as voice or data service. 
     When the user turns on UE  10 , UE  10  searches for a proper cell and stays in idle state in the cell. UE  10 , when required, establishes an RRC connection with the RRC layer of eNodeB  20  through an RRC connection procedure and transits to the RRC connected state. 
     There are a number of situations where the UE staying in the idle state needs to establish an RRC connection, for example, when the user attempts to call or when uplink data transmission is needed, or when transmitting a message responsive to reception of a paging message from the EUTRAN. 
     In order for the idle UE  10  to be RRC connected with eNodeB  20 , UE  10  needs to perform the RRC connection procedure as described above. The RRC connection procedure generally comes with the process in which UE  10  transmits an RRC connection request message to eNodeB  20 , the process in which eNodeB  20  transmits an RRC connection setup message to UE  10 , and the process in which UE  10  transmits an RRC connection setup complete message to eNodeB  20 . The processes are described in further detail with reference to  FIG. 6 . 
     1) The idle UE  10 , when attempting to establish an RRC connection, e.g., for attempting to call or transmit data or responding to paging from eNodeB  20 , sends an RRC connection request message to eNodeB  20 . 
     2) When receiving the RRC connection message from UE  10 , eNodeB  20  accepts the RRC connection request from UE  10  if there are enough radio resources, and eNodeB  20  sends a response message, RRC connection setup message, to UE  10 . 
     3) When receiving the RRC connection setup message, UE  10  transmits an RRC connection setup complete message to eNodeB  20 . If UE  10  successfully transmits the RRC connection setup message, UE  10  happens to establish an RRC connection with eNodeB  20  and switches to the RRC connected state. 
     Meanwhile, in order to solve a network overload problem, an eNodeB may broadcast information related to access class barring (ACB). Through the ACB, the UE may check whether an RRC connection request of its own is a barring target based on the ACB, and when the RRC connection request of the UE is not a barring target, the UE may transmit the RRC connection request. 
     However, network congestion may be aggravated due to an introduction of a machine type communication (MTC) device. In order to solve this, the eNodeB may broadcast extended assess barring (EAB)-related information. The MTC device may check whether an RRC connection request of its own is a barring target based on EAB, and only when the RRC connection request is not a barring target, the MTC device may transmit the RRC connection request. 
     The MTC communication is also called Internet of Things (IoT) communication since there is no intervention of a person. The IoT communication performed based on cellular, not Wireless LAN like Wi-Fi, is called CIoT. The CIoT supports a communication not based on IP as well as a communication based on IP, which is different from Wireless LAN. 
     Meanwhile, in order to support CIoT service, in 3GPP, a physical layer, that is, Radio Access Technology (RAT) has been improved. The improved RAT is called Narrowband-IoT (NB-IoT). 
     However, in the NB-IoT, which is improved RAT for the CIoT, an access control like ACB is not defined. Accordingly, it is unclear how to solve network overload and a network congested situation. Furthermore, when a network trial is barred in the network congested situation, a problem occurs that exceptional data to be urgently transmitted is also unable to be transmitted. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to present a method that can solve the aforementioned problem. 
     In order to achieve the above-described technical object, a disclosure of this specification provides a method for trying a network access. The method may be performed by a wireless device and comprise: receiving, by a radio resource control (RRC) layer of the wireless device and from a cell, first information related to a narrowband internet of things (NB-IoT) radio access technology (RAT); receiving, by the RRC layer and from the cell, second information indicating whether an access barring is applied or not for an exceptional data; acquiring, by the RRC layer and from an upper layer, a RRC establishment cause set to mobile originating (MO) exceptional data when a NAS(Non-Access Stratum) signaling procedure is initiated to transmit the exceptional data; and performing an access barring check. If the cell uses the NB-IoT RAT, if the RRC establishment cause is set to the MO exceptional data and if the second information indicates that the access barring is not applied thereby being skipped for the exceptional data, the access barring check may result in that a network access for transmitting the exceptional data is not barred. 
     The first information related to the NB-IoT RAT may be received via a master information block (MIB) or first information block (SIB). 
     The method may further comprise: receiving, by the RRC layer, second information indicating whether an access barring is applied or not for an exceptional data 
     The second information may be received via a system information block (SIB). 
     The MIB further may include: third information indicating whether the access barring is enabled or not. 
     The SIB further may include: a bitmap indicating whether the access baring is on or off. 
     The method may further comprise: setting, by the NAS layer, the RRC establishment cause to the MO exceptional data when a NAS signaling procedure is initiated to transmit the exceptional data. 
     The method may further comprise: if the network access for transmitting the exceptional data is not barred, transmitting a RRC connection request message 
     In order to achieve the above-described technical object, a disclosure of this specification provides a wireless device for trying a network access. The wireless device may comprise: a transceiver; and a processor configured to control the transceiver and include a radio resource control (RRC) layer and a non-access stratum (NAS) layer. The processor may control the transceiver to receive, via the RRC layer from a cell, first information related to a narrowband internet of things (NB-IoT) radio access technology (RAT) and second information indicating whether an access barring is applied or not for an exceptional data. The processor may control the RRC layer to acquire, from an upper layer, a RRC establishment cause set to mobile originating (MO) exceptional data when a NAS(Non-Access Stratum) signaling procedure is initiated to transmit the exceptional data. The processor may perform an access barring check. If the cell uses the NB-IoT RAT, if the RRC establishment cause is set to the MO exceptional data and if the second information indicates that the access barring is not applied thereby being skipped for the exceptional data, the access barring check may result in that a network access for transmitting the exceptional data is not barred. 
     According to the present disclosure, the aforementioned problems of the related art may be solved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structural diagram of an evolved mobile communication network. 
         FIG. 2  is an exemplary diagram illustrating architectures of a general E-UTRAN and a general EPC. 
         FIG. 3  is an exemplary diagram illustrating a structure of a radio interface protocol on a control plane between UE and eNodeB. 
         FIG. 4  is another exemplary diagram illustrating a structure of a radio interface protocol on a user plane between the UE and a base station. 
         FIG. 5 a    is a flowchart illustrating a random access process in 3GPP LTE. 
         FIG. 5 b    illustrates a connection process in a radio resource control (RRC) layer. 
         FIG. 6  illustrates a network overloaded state. 
         FIG. 7  is an exemplary flowchart illustrating an access barring operation in a network congested state. 
         FIG. 8  illustrates an example that all accesses by all applications are barred when ACB is applied. 
         FIG. 9  is a signal flowchart illustrating a procedure according to the ACDC. 
         FIG. 10 a    illustrates an example of the Machine Type communication (MTC) communication. 
         FIG. 10 b    illustrates an example in which network congestion is aggravated by MTC devices. 
         FIG. 11  illustrates an example of applying Extended Access Barring (EAB) to resolve congestion caused by MTC devices. 
         FIG. 12  is a signal flowchart illustrating proposal  1  of the present specification schematically. 
         FIG. 13  is a signal flowchart illustrating proposal  2  of the present specification schematically. 
         FIG. 14  is a block diagram illustrating a configuration of a wireless device  100  and a base station  200  according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The present invention is described in light of UMTS (Universal Mobile Telecommunication System) and EPC (Evolved Packet Core), but not limited to such communication systems, and may be rather applicable to all communication systems and methods to which the technical spirit of the present invention may apply. 
     The technical terms used herein are used to merely describe specific embodiments and should not be construed as limiting the present invention. Further, the technical terms used herein should be, unless defined otherwise, interpreted as having meanings generally understood by those skilled in the art but not too broadly or too narrowly. Further, the technical terms used herein, which are determined not to exactly represent the spirit of the invention, should be replaced by or understood by such technical terms as being able to be exactly understood by those skilled in the art. Further, the general terms used herein should be interpreted in the context as defined in the dictionary, but not in an excessively narrowed manner. 
     The expression of the singular number in the specification includes the meaning of the plural number unless the meaning of the singular number is definitely different from that of the plural number in the context. In the following description, the term ‘include’ or ‘have’ may represent the existence of a feature, a number, a step, an operation, a component, a part or the combination thereof described in the specification, and may not exclude the existence or addition of another feature, another number, another step, another operation, another component, another part or the combination thereof. 
     The terms ‘first’ and ‘second’ are used for the purpose of explanation about various components, and the components are not limited to the terms ‘first’ and ‘second’. The terms ‘first’ and ‘second’ are only used to distinguish one component from another component. For example, a first component may be named as a second component without deviating from the scope of the present invention. 
     It will be understood that when an element or layer is referred to as being “connected to” or “coupled to” another element or layer, it can be directly connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. 
     Hereinafter, exemplary embodiments of the present invention will be described in greater detail with reference to the accompanying drawings. In describing the present invention, for ease of understanding, the same reference numerals are used to denote the same components throughout the drawings, and repetitive description on the same components will be omitted. Detailed description on well-known arts which are determined to make the gist of the invention unclear will be omitted. The accompanying drawings are provided to merely make the spirit of the invention readily understood, but not should be intended to be limiting of the invention. It should be understood that the spirit of the invention may be expanded to its modifications, replacements or equivalents in addition to what is shown in the drawings. 
     In the drawings, user equipments (UEs) are shown for example. The UE may also be denoted a terminal or mobile equipment (ME). The UE may be a laptop computer, a mobile phone, a PDA, a smartphone, a multimedia device, or other portable device, or may be a stationary device such as a PC or a car mounted device. 
     Definition of Terms 
     For a better understanding, the terms used herein are briefly defined before going to the detailed description of the invention with reference to the accompanying drawings. 
     An UMTS is an abbreviation of a Universal Mobile Telecommunication System, and it refers to the core network of the 3rd generation mobile communication. 
     UE/MS is an abbreviation of User Equipment/Mobile Station, and it refers to a terminal device. 
     An EPS is an abbreviation of an Evolved Packet System, and it refers to a core network supporting a Long Term Evolution (LTE) network and to a network evolved from an UMTS. 
     A PDN is an abbreviation of a Public Data Network, and it refers to an independent network where a service for providing service is placed. 
     A PDN connection refers to a connection from UE to a PDN, that is, an association (or connection) between UE represented by an IP address and a PDN represented by an APN. 
     A PDN-GW is an abbreviation of a Packet Data Network Gateway, and it refers to a network node of an EPS network which performs functions, such as the allocation of a UE IP address, packet screening &amp; filtering, and the collection of charging data. 
     A Serving gateway (Serving GW) is a network node of an EPS network which performs functions, such as mobility anchor, packet routing, idle mode packet buffering, and triggering an MME to page UE. 
     A Policy and Charging Rule Function (PCRF): The node of an EPS network which performs a policy decision for dynamically applying QoS and a billing policy that are different for each service flow. 
     An Access Point Name (APN) is the name of an access point that is managed in a network and provides to UE. That is, an APN is a character string that denotes or identifies a PDN. Requested service or a network (PDN) is accessed via P-GW. An APN is a name (a character string, e.g., ‘intemet.mnc012.mcc345.gprs’) previously defined within a network so that the P-GW can be searched for. 
     A Tunnel Endpoint Identifier (TEID): The end point ID of a tunnel set between nodes within a network, and it is set for each bearer unit of each UE. 
     A NodeB is an eNodeB of a UMTS network and installed outdoors. The cell coverage of the NodeB corresponds to a macro cell. 
     An eNodeB is an eNodeB of an Evolved Packet System (EPS) and is installed outdoors. The cell coverage of the eNodeB corresponds to a macro cell. 
     An (e)NodeB is a term that denotes a NodeB and an eNodeB. 
     An MME is an abbreviation of a Mobility Management Entity, and it functions to control each entity within an EPS in order to provide a session and mobility for UE. 
     A session is a passage for data transmission, and a unit thereof may be a PDN, a bearer, or an IP flow unit. The units may be classified into a unit of the entire target network (i.e., an APN or PDN unit) as defined in 3GPP, a unit (i.e., a bearer unit) classified based on QoS within the entire target network, and a destination IP address unit. 
     A PDN connection is a connection from UE to a PDN, that is, an association (or connection) between UE represented by an IP address and a PDN represented by an APN. It means a connection between entities (i.e., UE-PDN GW) within a core network so that a session can be formed. 
     UE context is information about the situation of UE which is used to manage the UE in a network, that is, situation information including an UE ID, mobility (e.g., a current location), and the attributes of a session (e.g., QoS and priority) 
     OMA DM (Open Mobile Alliance Device Management): a protocol designed for managing mobile devices such as mobile phones, PDAs, or portable computers and performs functions such as device configuration, firmware upgrade, and error reporting. 
     OAM (Operation Administration and Maintenance): denotes a group of network management functions displaying network faults and providing capability information, diagnosis and data. 
     NAS configuration MO (Management Object): MO (Management Object) used to configure in UE parameter associated with NAS functionality 
     NAS (Non-Access-Stratum): A higher stratum of a control plane between a UE and an MME. The NAS supports mobility management, session management, IP address management, etc., between the UE and the network. 
     MM (Mobility Management) operation/procedure: An operation or procedure for mobility regulation/management/control of the UE. The MM operation/procedure may be interpreted as including one or more of an MM operation/procedure in a CS network, a GMM operation/procedure in a GPRS network, and an EMM operation/procedure in an EPS network. The UE and the network node (e.g., MME, SGSN, and MSC) exchange an MM message to perform the MM operation/procedure. 
     SM (Session Management) operation/procedure: An operation or procedure for regulating/managing/processing/handling a user plane and/or a bearer context/PDP context of the UE. The SM operation/procedure may be interpreted as including one or more of an SM operation/procedure in a GPRS network and an ESM operation/procedure in an EPS network. The UE and the network node (e.g., MME and SGSN) exchange an SM message to perform the SM operation/procedure. 
     Low priority UE: A UE configured for NAS signalling low priority. The standard document 3GPP TS 24.301 and TS 24.008 may be incorporated by reference for details thereof. 
     Normal priority UE: A normal UE not configured with low priority. 
     Dual priority UE: A UE configured for dual priority. That is, a UE which provides dual priority support is configured for a NAS signalling low priority and also configured to override the NAS signalling low priority indicator. The standard document 3GPP TS 24.301 and TS 24.008 may be incorporated by reference for details thereof. 
     PLMN: as an abbreviation of Public Land Mobile Network, means a network identification number of a mobile communication provider. In roaming case of the UE, the PLMN is classified into a home PLMN (HPLMN) and a vistied PLMN (VPLMN). 
     CIoT: An abbreviation of Cellular Internet of Things, and means performing based on IoT communication. 
     Control plane CIoT EPS optimization: A signaling optimization on a control plane that enables efficient transmission of user data (user data based on IP or non-IP or SMS) 
     User plane CIoT EPS optimization: A signaling optimization on a user plane that enables efficient transmission of user data (user data based on IP or non-IP or SMS) 
     UE supporting CIoT EPS optimization: A UE that supports Control plane CIoT EPS optimization or User plane CIoT EPS optimization and one or more other CIoT EPS optimizations 
     NB-S1 mode: This means a mode operating as an improved RAT (radio access technology) for NB (Narrowband) IoT 
     WB-S1 mode: This means a mode operating as a normal RAT, not an improved RAT for NB IoT 
     Hereinafter, an aspect of the present specification is described with reference to the accompanying drawings. 
       FIG. 6  shows a network overload state. 
     As shown in  FIG. 6 , many UEs  100   a ,  100   b ,  300   c , and  300   d  are present in the coverage of an eNodeB  200 , and data transmission/reception is attempted. Accordingly, if traffic is overloaded or congested in an interface between the eNodeB  200  and an S-GW  520 , downlink data to the MTC device  100  or uplink data from the UE  100  is not correctly transmitted and thus data transmission fails. 
     Alternatively, even if an interface between the S-GW  520  and a PDN-GW  530  or an interface between the PDN-GW  530  and an Internet Protocol (IP) service network of a mobile communication operator is overloaded or congested, downlink data to the UEs  100   a ,  100   b ,  300   c , and  300   d  or uplink data from the UEs  100   a ,  100   b ,  300   c , and  300   d  is not correctly transmitted and thus data transmission fails. 
     If an interface between the eNodeB  200  and the S-GW  520  is overloaded or congested or if an interface between the S-GW  520  and the PDN-GW  530  is overloaded or congested, a node (e.g., MME) of the core network performs a NAS level congest control to avoid or control signaling congestion and APN congestion. 
     The NAS level congestion control consists of an APN based congestion control and a general NAS level mobility management control. 
     The APN based congestion control implies an EMM, GMM, and (E)SM signal congestion control related to a UE and a specific APN (i.e., an APN related to a congestion state), and includes an APN based session management congestion control and an APN based mobility management congestion control. 
     On the other hand, the general NAS level mobility management control implies that a node (MME, SGSN) in the core network rejects a mobility management signaling request which is requested by the UE/MS in a general network congestion or overload situation to avoid the congestion and the overload. 
     In general, if the core network performs the NAS level congestion control, a back-off timer value is transmitted to a UE in an idle mode or a connected mode by being carried on a NAS reject message. In this case, the UE does not request an EMM/GMM/(E)SM signal to the network until the back-off timer expires. The NAS reject message is one of an Attach reject, a Tracking Area Updating (TAU) reject, a Routing Area Updating (RAU) reject, a service reject, an extended service reject, a PDN connectivity reject, a bearer resource allocation reject, a bearer resource modification reject, and a deactivate EPS bearer context request reject. 
     The back-off timer may be classified into a Mobility Management (MM) back-off timer and a Session Management (SM) back-off timer. 
     The MM back-off timer operates independently for each UE, and the SM back-off timer operates independently for each APN and each UE. 
     Simply, the MM back-off timer is for controlling an EMM/GMM signal (e.g., Attach, TAU/RAU request, etc.). The SM back-off timer is for controlling an (E)SM signal (e.g., PDN connectivity, Bearer Resource Allocation, Bearer Modification, PDP Context Activation, PDP Context Modification request, etc.). 
     More specifically, the MM back-off timer is a mobility management related back-off timer used to control a case where a network congestion occurs, and is a timer which prevents the UE from performing an attach, location information update (TAU, RAU), and service request procedure during the timer is running. However, exceptionally in case of an emergency bearer service and a Multimedia Priority Service (MPS), the UE may be allowed to perform the request even if the timer is running 
     As described above, the UE may receive the MM back-off timer value from a core network node (e.g., MME, SGSN, etc.) or from a lower layer (access stratum). In addition, the timer value may be randomly set by the UE within the range of 15 minutes to 30 minutes. 
     The SM back-off timer is a session management related back-off timer used to control a case where a network congestion occurs, and is a timer which prevents the UE from configuring or changing an associated APN-based session. However, likewise, exceptionally in case of an emergency bearer service and a Multimedia Priority Service (MPS), the UE  100  may be allowed to perform the request even if the timer is running 
     The UE receives the SM back-off timer value from the core network node (e.g., MME, SGSN, etc.), and is randomly set within up to 72 hours. In addition, the timer value may be randomly set by the UE/MS within the range of 15 minutes to 30 minutes. 
     On the other hand, when the congestion occurs in the eNodeB  200 , the eNodeB  200  may perform congestion control. That is, when the UE requests RRC connection establishment for data transmission of the user plane, if the eNodeB  200  is in the congest state, the eNodeB  200  may transmit a reject response to the UE together with an extended wait timer. In this case, the RRC connection establishment request may not be re-attempted until the extended wait timer expires. On the contrary, when the UE requests the RRC connection for transmitting the signal of the control plane for circuit switch (CS)-based call reception, even through the eNodeB  200  is in the congest state, the RRC connection request may not be rejected. 
       FIG. 7  is an exemplary flowchart illustrating an access barring operation in a network congested state. 
     As illustrated in  FIG. 7 a   , in the overload or congest state of the network or the eNodeB  200 , the eNodeB  200  may broadcast access class barring (ACB)-related information through system information. The system information may be system information block (SIB) type  2 . 
     The SIB type  2  may include ACB-related information like the following table. 
     
       
         
           
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Field 
                 Description 
               
               
                   
               
             
            
               
                 ac-BarringFactor 
                 When a random value generated by the UE is 
               
               
                   
                 smaller than a value of ac-BarringFactor, 
               
               
                   
                 accessis allowed. If not, the access is 
               
               
                   
                 barred. 
               
               
                 ac-BarringForCSFB 
                 ACB for circuit switch (CS) fallback. The 
               
               
                   
                 CS fallback converts a VoLTE call to a 
               
               
                   
                 previous 3G call. 
               
               
                 ac-BarringForEmergency 
                 ACB for emergency service 
               
               
                 ac-BarringForMO-Data 
                 ACB for mobile orienting data 
               
               
                 ac- 
                 ACB for mobile orienting control signal 
               
               
                 BarringForMO-Signalling 
               
               
                 ac- 
                 ACB for specific access classes, that is, 
               
               
                 BarringForSpecialAC 
                 11 to 15. 
               
               
                 ac-BarringTime 
                 Represents time when the access is barred. 
               
               
                 ssac- 
                 ACB for each service for mobile orienting of 
               
               
                 BarringForMMTEL-Video 
                 MMTEL video. 
               
               
                 ssac- 
                 ACB for each service for mobile orienting of 
               
               
                 BarringForMMTEL-Voice 
                 MMTEL voice. 
               
               
                   
               
            
           
         
       
     
     Meanwhile, UE 1   100   a  determines an IMS service, for example, mobile orienting of a call by VoLTE and generates a service request message. Similarly, UE 2   100   b  determines mobile orienting of general data and generate the service request message. 
     Sequentially, the UE 1   100   a  generates an RRC connection request message. Similarly, the UE 2   100   b  generate the RRC connection request message. 
     Meanwhile, the UE 1   100   a  performs access barring check (that is, whether the ACB is applied). Similarly, the UE 2   100   b  performs access barring check (that is, whether the ACB is applied). 
     If the ACB is not applied, the UE 1   100   a  and the UE 2   100   b  may transmit a service request (alternatively, an extended service request) message and the RRC connection request message, respectively. However, when the ACB is applied, both the UE 1   100   a  and the UE 2   100   b  may not transmit the RRC connection request message, respectively. 
     The access barring check will be described in detail as follows. Generally, at least one of 10 access classes (for example, AC 0 , AC 1 , . . . , and AC 9 ) is randomly allocated to the UE. Exceptionally, for urgent emergency access, AC 10  is allocated. As such, the value of the randomly allocated access class may be stored in each USIM of the UE 1   100   a  and the UE 2   100   b . Then, the UE 1   100   a  and the UE 2   100   b  verify whether the access barring is applied, by using a barring factor included in the received ACB-related information, based on the stored access class. The access barring check is performed in each access stratum (AS) layer, that is, an RRC layer of the UE 1   100   a  and the UE 2   100   b.    
     The access barring check will be described in more detail as follows. 
     The ac-BarringPerPLMN-List is included in the SIB type  2  received by each of the UE 1   100   a  and the UE 2   100   b , and in the case where AC-BarringPerPLMN entry matched with plmn-identityIndex corresponding to the PLMN selected in an higher layer is included in the ac-BarringPerPLMN-List, AC-BarringPerPLMN entry matched with the plmn-identityIndex corresponding to the PLMN selected by the higher layer is selected. 
     Next, when the UE 1   100   a  and the UE 2   100   b  perform the RRC connection request, the access barring check is performed by using T 303  as Tbarring and using ac-BarringForMO-Data as a barring parameter. 
     When the barring is determined, each AS(RRC) layer of the UE 1   100   a  and the UE 2   100   b  notifies a failure of the RRC connection establishment to the higher layer. 
     Subsequently, as such, when the access is barred, each AS(RRC) layer determines whether a T 302  timer or a Marring timer is driving. If the timer is not driving, the T 302  timer or the Marring timer is driven. 
     Meanwhile, while the T 302  timer or a Tbarring timer is driving, the AS(RRC) layer considers that all the access to the corresponding cell is barred. 
     As described above, in the network overload and congest situation, the eNB/RNC provides the ACB-related information to the UE. Then, the UE checks the access barring by using the barring factor included in the received ACB information based on its access class stored in the USIM. Through the access barring check, finally, an access attempt is not performed. That is, when the access to the corresponding cell is barred through the access barring check, the UE does not attempt the access, and when the access to the corresponding cell is not barred, the UE attempts the access. The access barring check is performed in the AS layer. Herein, the access attempt means that the AS(RRC) layer of the UE transmits the RRC connection request message to the eNB/RNC. 
     Meanwhile, an access barring check is performed with respect to a normal Mobile Originating (MO) service, for example, an originating call, an originating data, an originating IMS voice and an originating IMS video. That is, ACB is applied accesses of all application programs (however, except a response to an urgent service or paging). 
       FIG. 8  illustrates an example that all accesses by all applications are barred when ACB is applied. 
     As can be seen with reference to  FIG. 8 , when it is determined to apply ACB once, accesses by all applications of UE (however, except a response to an urgent service or paging) are barred. 
     As such, accesses by all applications are barred, a differentiated service is unavailable. Such a problem causes network resource waste and degrades user experience, consequently. 
     Accordingly, in a situation of network overload and a congested situation, a method is required for differentiating Mobile Originating service (e.g., mobile originating voice call or mobile originating data) for each of specific application groups/categories. However, there has been no method for implementing it in the conventional art. 
     &lt;Introduction of Application Specific Congestion Control Data Communication (ACDC)&gt; 
     As a method for differentiating a normal Mobile Originating (MO) service, for example, an originating call, an originating data, an originating IMS voice and an originating IMS video, the Application specific Congestion control for Data Communication (ACDC) is proposed. 
       FIG. 9  is a signal flowchart illustrating a procedure according to the ACDC. 
     The procedure is described with reference to  FIG. 9  as below. 
     First, a network (e.g., eNB) may provide ACDC barring information to a UE through SIB. 
     Meanwhile, in the case that a specific application is executed in the UE  100  and a data communication service is requested by the specific application, the application layer that manages the execution of the specific application provides application attribute related information to a NAS layer. 
     Then, the NAS layer of the UE  100  determines an application category for the ACDC based on the application attribute related information received from the application layer. 
     Subsequently, when the NAS layer of the UE  100  starts a service request procedure for service connection (a transmission of SERVICE REQUEST message or a transmission of EXTENDED SERVICE REQUEST message), the NAS layer of the UE  100  forwards the information for the application category to an AS layer (i.e., RRC layer). 
     Before the AS layer (i.e., RRC layer) of the UE  100  performs the service request procedure of the NAS layer (a transmission of SERVICE REQUEST message or a transmission of EXTENDED SERVICE REQUEST message), based on the category of the application and the ACDC barring information received from the network, the AS layer (i.e., RRC layer) of the UE  100  performs the ACDC barring check, and accordingly, determines whether to permit the service request procedure or not. 
     In the case that the service request procedure is permitted as a result of the ACDC barring check, the AS layer (i.e., RRC layer) of the UE  100  transmits an RRC Connect Request message to an eNodeB  200 . 
     As described above, the service requested by the application which is executing in a UE may be differentiated and allowed or barred through the ACDC. 
     &lt;Machine Type Communication (MTC) Communication&gt; 
     The Machine Type Communication (MTC) means a communication established between a machine and a machine, in which a person is excluded, and the device used in this case is referred to an MTC device. The service provided through an MTC device is discriminated from the communication service in which a person intervenes, and may be applied to various ranges of services. 
       FIG. 10 a    illustrates an example of the Machine Type communication (MTC) communication. 
     The Machine Type Communication (MTC) is referred to information interchange between MTC devices  100  through an eNodeB  200  in which human interaction is not accompanied or information interchange between an MTC device and an MTC server  700  through an eNodeB. 
     The MTC server  700  is an entity that communicates with an MTC device  100 . The MTC server  700  executes an MTC application and provides a MTC-specific service to the MTC device. 
     The MTC device  100  is a wireless device that provides an MTC communication, and may be fixed or mobile. 
       FIG. 10 b    illustrates an example in which network congestion is aggravated by MTC devices. 
     As can be seen from  FIG. 10 b   , numerous MTC devices may be disposed within coverage of an eNodeB. Thus, network congestion may be further aggravated. 
       FIG. 11  illustrates an example of applying Extended Access Barring (EAB) to resolve congestion caused by MTC devices. 
     As shown in  FIG. 11 , an MTC device is configured to have low priority. In addition, in order to resolve congestion caused by the MTC device, the eNodeB broadcasts system information including EAB information. The system information including the EAB information may be system information block (SIB) type 14. 
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Description of SIB Type14 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 eab-BarringBitmap 
               
               
                 A bitmap for access classes (ACs) 0 to 9. The left most bit in the 
               
               
                 bitmap is for AC 0 and the nest bit is for AC 1. 
               
               
                 eab-Category 
               
               
                 This represents a category of UE to which EAB is applied. 
               
               
                 eab-Common 
               
               
                 This is an EAB parameter applied for all PLMNs. 
               
               
                 eab-PerPLMN-List 
               
               
                 This is an EAB parameter for each PLMN, enumerated in PLMN order. 
               
               
                   
               
            
           
         
       
     
     In addition, the eNodeB includes configuration information regarding whether a specific MTC device should apply EAB, that is, EAB configuration information, in a NAS configuration Management Object (MO) and transfers the same to the specific MTC device. When the low priority and EAB are set, a NAS layer of the MTC device informs an RRC layer about an indication regarding whether EAB is applied with respect to a corresponding NAS service request (e.g., Attach request procedure, TAU/RAU request procedure, Service Request procedure, Extended service request procedure, Data service request procedure, etc.), excluding a case corresponding to an emergency call, mobile terminated (MT) access, or a high priority access class (e.g., AC 11-15), and the RRC layer controls access by applying EAB when performing an RRC connection establishment procedure with respect to the corresponding request with the indication to apply EAB. 
     Accordingly, as illustrated, when an application layer APP of the MTC device  100  informs that a data transmission is required, the NAS layer determines to apply EAB based on EAB configuration. In addition, the application layer APP forwards a NAS service request to the RRC layer. At this time, indication to apply EAB is also delivered together with the NAS service request. 
     The RRC layer of the MTC device determines whether an RRC connection establishment request corresponds to EAB application. In the case that the EAB is applied, a transmission of the RRC connection establishment request message by the RRC layer is barred (or prohibited). 
     &lt;Cellular Internet of Things (CIoT) Communication&gt; 
     The MTC communication is also called Internet of Things (IoT) communication since there is no intervention of a person. The IoT communication performed based on cellular, not Wireless LAN like Wi-Fi, is called CIoT. The CIoT supports a communication not based on IP as well as a communication based on IP, which is different from Wireless LAN. 
     Meanwhile, in order to support CIoT service, in 3GPP, a physical layer, that is, Radio Access Technology (RAT) has been improved. The improved RAT is called Narrowband-IoT (NB-IoT). 
     The RAT improved for the NB-IoT uses an optimized physical layer (e.g., carrier bandwidth is 180 kHz, and subcarrier spacing is 3.75 kHz or 15 kHz) for very low power consumption. In the NB-IoT RAT, the various services which have been developed for the existing RAT may not be provided. Particularly, an urgent service using an emergency bearer, access class barring (ACB), EAB, ACDC, SSAC and the like are not be provided. 
     In such a CIoT service environment, many CIoT devices perform data transmissions, and in this case, network overload or congestion situation may occur. This case is solved by performing ACB perviously, but in NB-IoT, which is improved RAT for CIoT, the access control like ACB is not provided. Thus, it is unclear how to settle the network overload or congestion situation. 
     Moreover, in a situation in which normal data transmission (e.g., normal state report) is barred owing to the access control in the CIoT service environment, it is required a processing method for the case that it is required to transmit urgent state report or exceptional report). That is, it is required to distinguish normal data transmission and urgent data transmission when CIoT devices perform data transmissions in the CIoT service environment. 
     &lt;Disclosure of the Present Specification&gt; 
     Accordingly, a disclosure of the present specification proposes proposals to solve the problem described above. 
     Particularly, the proposals according to a disclosure of the present specification proposes an efficient access control method for connecting a voice call (VoLTE) or a data communication for a Mobile Originating (MO) service (e.g., MO voice call, MO data or MO signal) of CIoT device (or UE) in a CIoT service support situation. 
     Meanwhile, in the CIoT service support situation, a network may forward an indicator indicating that CIoT service is supported to a CIoT device (or UE), for example, Indicator for CIoT using a Management Object according to a Device Management technique of Open Mobile Alliance (OMA). Otherwise, a network may forward an indicator indicating that CIoT service is supported, for example, NAS signalling CIoT indicator (or signalling NB-IoT indicator). 
     Only in the case that the CIoT device receives the indicator, the CIoT device may apply the Access control for the CIoT technique, which is proposed in the present specification. Otherwise, alternatively, even in the case that the CIoT device receives the existing NAS signalling low priority indicator through NAS configuration MO, or receives an indicator for exceptional data request, or does not receive any indicator, the access control for CIoT, which is proposed in the present specification. 
     Meanwhile, the network (e.g., eNB) may provide an indicator indicating that the access control for CIoT is applied (e.g., Access control for CIoT Indicator) to the CIoT device (or UE) in associated with or regardless of the indicator (i.e., Indicator for CIoT or NAS signalling CIoT indicator) or the new indicator for the exceptional data request (i.e., indicator for exceptional data request). The access control for CIoT proposed in the present specification may be applied to the CIoT device only in the case that the CIoT device receives the indicator (i.e., Access control for CIoT Indicator). 
     The network (e.g., eNB) may forward the information related to the access control for CIoT proposed in the present specification (e.g., Access control parameters for CIoT) to AS layer (i.e., RRC layer) of the CIoT device (or UE) through Master Information Block (MIB) or System Information Block (SIB). The related information (e.g., Access control parameters for CIoT) may be defined and included in SIB 2 , SIB 14  or new SIB(xx). At this time, the related information that the network provides through MIB or SIB may include information for Barring time and Barring rate. In addition, the related information may include a bitmap indicating whether to bar (e.g., indicating on/off of Barring). Meanwhile, since the originating exception service may be an urgent service, in order to perform an RRC connection establishment or a connection resume quickly, for the originating exception service, the bitmap may indicate skip/pass of the barring check of an access control or indicate OFF. The relation information included in MIB or SIB may include information for the CIoT device to turn on/off skip/pass the barring check of the access control of CIoT (skip/pass=On/Off information/indication/flag, etc.). Accordingly, the originating exception service may be discriminated from a normal data service. 
     Hereinafter, the proposals proposed in the present specification are described one by one. 
     I. Proposal 1 
     When an Application layer (or including IMS layer) of a CIoT device requests a call or a data transmission for mobile originating (MO) service to a NAS layer, the NAS layer of the CIoT device may setup a call type and an RRC establishment cause field for the MO service as below. 
     1) With respect to signaling such as Attach request message, Tracking Area Update (TAU)/Routing Area Update (RAU) request message, service request message, extended service request message, and data service request message, the CIoT device may 
     Setup the call type as (Mobile) originating signalling, “originating MMTEL voice for MMTEL voice”, “originating MMTEL video for MMTEL video”, “originating SMSoIP for SMS over IP”, or “originating SMS for SMS over NAS”. And, 
     Setup the RRC establishment cause field as MO signalling. 
     2) With respect to (normal) call or data, the CIoT device may 
     Setup the call type as (Mobile) originating calls, “originating MMTEL voice for MMTEL voice”, “originating MMTEL video for MMTEL video”, “originating SMSoIP for SMS over IP”, or “originating SMS for SMS”. And, 
     Setup the RRC establishment cause field as MO data. 
     3) With respect to Mobile Terminate (MT) service, the CIoT device may 
     Setup the call type as (Mobile) terminating calls. And 
     Setup the RRC establishment cause field as MT access. 
     4) With respect to call, data or signaling for (urgent data, exceptional data), the CIoT device 
     Setup the call type as call type: (Mobile) originating exception (or MO exception calls) or (Mobile) originating calls or (Mobile) originating signalling. And 
     Setup the RRC establishment cause field as MO exception (or MO exception data, MO exception signalling, etc.). 
     At this time, the distinguishing between normal data and exceptional data is performed in an application layer, and the application may provide information/indication to a NAS layer by distinguishing them separately. 
     When the NAS layer starts the NAS signaling request procedure (e.g., Attach request procedure, TAU/RAU request procedure, service request procedure, extended service request procedure, data service request procedure, etc.) for data transmission, the NAS layer configures the voice call type and the RRC establishment cause field as above, and provides it to the AS layer (i.e., RRC layer). 
     Based on the call type and the RRC establishment cause field, the AS layer (i.e., RRC layer) performs barring check for access control according to related information in relation to the access control for CIoT (e.g., Access control parameters for CIoT) provided through MIB or SIB from the network. The access control may differentiate the NAS signaling request procedure based on probability. Or, the access control may determine whether to bar access based on bitmap. 
     At this time, since the mobile originating exceptional service is for urgent data, the AS layer determines whether to skip/pass the barring check according to the call type (e.g., MO exception calls or MO exception signalling), the RRC establishment cause field (e.g., MO exception) and the information for turning on/off skip/pass of the barring check for the access control for CIoT (skip/pass=On/Off information/indication/flag, etc.). 
     Alternatively, even in the case that the NAS layer setup the call type as the same as previously (i.e., originating calls or signalling) for the mobile originating exceptional service and forward the same to the AS layer (i.e., RRC layer), when the AS layer receives an indication indicating that the access control for CIoT is applied from the network, the AS layer may substitute/change the establishment cause field to MO exception and performs the barring check. 
     Meanwhile, the CIoT device may receive an indicator to override the barring check of the access control for CIoT (e.g., Overriding Indicator for CIoT or Overriding NAS signalling CIoT) together with an indicator indicating that the CIoT service is supported (e.g., Indicator for CIoT) from the network. In this case, the CIoT device may skip the barring check for the mobile originating exceptional service. Or, in the case that NAS signalling low priority indicator is set for the CIoT device or Overriding NAS signalling low priority indicator is set, the CIoT device (or UE) may skip/pass the barring check for the access control for CIoT with respect to the mobile originating exceptional service. 
     Meanwhile, hereinafter, a relation with other access control mechanism is described exemplarily. 
     I-1. EXAMPLE 1 
     When the CIoT device receives NAS signalling low priority indicator from the network, for the originating signaling and originating call, the RRC layer of the CIoT device may substitute/change the RRC establishment cause field “Delaytolerant” to “MO data” which is set by the NAS layer and perform the access barring check. 
     Additionally, when the CIoT device receives Overriding NAS signalling low priority indicator from a network, for the mobile originating exceptional service, the RRC layer of the CIoT device may substitute/change the RRC establishment cause field “Delaytolerant” (or MO data)” to “MO exception”, and then, perform the barring check. 
     I-2. EXAMPLE 2 
     Meanwhile, for the mobile originating exceptional service for exceptional data, when the CIoT device (or UE) receives the following configuration through an management object using OMA DM technique, 
     NAS signalling low priority indicator; 
     Override NAS signalling low priority indicator 
     The NAS layer does not setup the RRC establishment cause field as Delaytolerant or MO data, but setup as mo-exception. 
     Then, based on the call type (i.e., MO exception calls or MO exception signalling), the RRC establishment cause field (e.g., MO exception) and the information on whether to skip/pass the barring check provided from the network (skip/pass=On/Off information/indication/flag, etc.), the AS layer determines whether to skip the barring check. 
     Otherwise, the NAS layer may setup the RRC establishment cause field as Delaytolerant (or MO data) as previously and provide the same to the AS layer, but the AS layer (i.e., RRC layer) may setup the RRC establishment cause field by substituting to mo-exception. And the AS layer (i.e., RRC layer) may determine whether to skip the barring check based on the information on whether to whether to skip/pass the barring check provided from the network. 
     Meanwhile, in the case that the network supports a CIoT service, the network may inform the information indicating the RAT that supports the CIoT service to the CIoT device (or UE) through SIB or MIB. When the AS layer (i.e., RRC layer) of the CIoT device (or UE) receives such information, the AS layer (i.e., RRC layer) may forward the same to the NAS layer (i.e., RRC layer). The contents described above may operate when the CIoT device receives the information or regardless of reception of the information. 
     On the other hand, even in the case that the CIoT device (or UE) roams to a visit network, in order to apply the contents described above, the visit network may forward (separate/additional) configuration/indicator/information for the process of the mobile originating exceptional service, NAS configuration management object or new configuration management object to the CIoT device. At this time, the case that configuration/indicator/information is set to 0 means the operation according to the contents described above in the roaming situation is not supported/performed, and the case that configuration/indicator/information is set to 1 means the operation according to the contents described above in the roaming situation is supported/performed. Such configuration/indicator/information may be determined by policy/configuration of a network provider or subscriber information, and the like. 
     I-3. EXAMPLE 3 
     For the mobile originating exceptional service for exceptional data in a network environment that supports a CIoT service, when the CIoT device (or UE) receives the following configuration through an management object using OMA DM technique, 
     NAS signalling low priority indicator 
     (new) indicator for exceptional data request/report 
     The NAS layer of the CIoT device (or UE) does not setup the RRC establishment cause field as Delaytolerant or MO data, but setup as mo-exception. 
     The AS layer (i.e., RRC layer) of the CIoT device (or UE) determines whether to skip/pass the barring check according to the call type (e.g., MO exception calls or MO exception signalling), the RRC establishment cause field (e.g., MO exception) and the information for turning on/off skip/pass of the barring check for the access control for CIoT (skip/pass=On/Off information/indication/flag, etc.). 
     Otherwise, the NAS layer may setup the RRC establishment cause field as Delaytolerant or MO data as previously and provide the same to the AS layer (i.e., RRC layer), but the AS layer (i.e., RRC layer) may setup the RRC establishment cause field by substituting to mo-exception. Based on this, the AS layer (i.e., RRC layer) may determine whether to skip/pass the barring check according to the information for turning on/off skip/pass of the barring check for the access control for CIoT (skip/pass=On/Off information/indication/flag, etc.). 
     In the case that the network supports a CIoT service, the network forward the information indicating the RAT that supports the CIoT service to the CIoT device (or UE) through SIB or MIB. The AS layer (i.e., RRC layer) of the CIoT device (or UE) may receive such information, and then, the AS layer (i.e., RRC layer) may provide the same to the NAS layer (i.e., RRC layer). The operation according to the contents described above may be performed when the CIoT device obtains the information (i.e., NB-IoT support RAT). 
     On the other hand, even in the case that the CIoT device (or UE) roams to a visit network, in order to apply the contents described above, the visit network may forward (separate/additional) configuration/indicator/information for the process of the mobile originating exceptional service, NAS configuration management object or new configuration management object to the CIoT device. At this time, the case that configuration/indicator/information is set to 0 means the operation according to the contents described above in the roaming situation is not supported/performed, and the case that configuration/indicator/information is set to 1 means the operation according to the contents described above in the roaming situation is supported/performed. Such configuration/indicator/information may be determined by policy/configuration of a network provider or subscriber information, and the like. 
     I-4. EXAMPLE 4 
     For the mobile originating exceptional service for exceptional data in a network environment that supports a CIoT service, when the CIoT device (or UE) receives the following configuration through an management object using OMA DM technique, 
     NAS signalling low priority indicator; 
     Override NAS signalling low priority indicator; 
     (new) indicator for exceptional data request/report 
     The NAS layer of the CIoT device (or UE) does not setup the RRC establishment cause field as Delaytolerant or MO data, but setup as mo-exception. 
     The AS layer (i.e., RRC layer) determines whether to skip/pass the barring check according to the call type (e.g., MO exception calls or MO exception signalling), the RRC establishment cause field (e.g., MO exception) and the information for turning on/off skip/pass of the barring check for the access control for CIoT (skip/pass=On/Off information/indication/flag, etc.). 
     Otherwise, the NAS layer may setup the RRC establishment cause field as Delaytolerant or MO data as previously and provide the same to the AS layer (i.e., RRC layer), but the AS layer (i.e., RRC layer) may setup the RRC establishment cause field by substituting to mo-exception. Based on this, the AS layer (i.e., RRC layer) may determine whether to skip/pass the barring check according to the information for turning on/off skip/pass of the barring check for the access control for CIoT (skip/pass=On/Off information/indication/flag, etc.). 
     As described above, in the case that the network supports a CIoT service, the network forward the information indicating the RAT that supports the CIoT service to the CIoT device (or UE) through SIB or MIB. The AS layer (i.e., RRC layer) of the CIoT device (or UE) may receive such information, and then, the AS layer (i.e., RRC layer) may provide the same to the NAS layer (i.e., RRC layer). The operation according to the contents described above may be performed when the CIoT device obtains the information (i.e., NB-IoT support RAT). 
     In addition, as described above, even in the case that the CIoT device (or UE) roams to a visit network, in order to apply the contents described above, the visit network may forward (separate/additional) configuration/indicator/information for the process of the mobile originating exceptional service, NAS configuration management object or new configuration management object to the CIoT device. At this time, the case that configuration/indicator/information is set to 0 means the operation according to the contents described above in the roaming situation is not supported/performed, and the case that configuration/indicator/information is set to 1 means the operation according to the contents described above in the roaming situation is supported/performed. Such configuration/indicator/information may be determined by policy/configuration of a network provider or subscriber information, and the like. 
     As described above, in the case of the originating exception service, different from other general mobile originating signaling or mobile originating voice call, when barring check is performed, RRC connection establishment or RRC connection reestablishment is guaranteed. At this time, the originating exception service is similar to an urgent service in the fact that it may transmit urgent data, but different from the urgent service in the fact that an emergency bearer is not setup. That is, the originating exception service enables fast NAS/RRC connection establishment or RRC connection reestablishment to be available, not configuring the urgent bearer. 
     The urgent service using the urgent bearer is used for providing IMS urgent session. The urgent service using the urgent bearer is provided to the UE that performs an urgent Attach. However, the urgent service using the urgent bearer may also be provided to the UE that performs a normal Attach according to a regulation of each nation. In order to use the urgent service using the urgent bearer, RRC establishment cause is setup as emergency. Meanwhile, in the case that a UE uses NB-IoT RAT, the urgent service using the urgent bearer is not supported. 
     Meanwhile, in the case of Mobile Terminating (MT) service, considering the importance of a reception service, barring through the access control for CIoT is not performed. 
     The contents of proposal 1 are summarized as below. 
     The CIoT device may skip the barring check of the access control for the mobile originating (MO) exception. 
     The network may broadcast the information related to the access control for a CIoT service through MIB or SIB. 
     When the NAS layer indicates a call type and a mobile originating exception, the RRC layer of the CIoT device may determine whether to skip the barring check of the access control for the RRC connection establishment and the RRC connection reestablishment. 
     The contents of proposal 1 and the examples are summarized as below. 
       FIG. 12  is a signal flowchart illustrating proposal 1 of the present specification schematically. 
     As illustrated, a wireless device receives information informing the RAT that supports a CIoT service (i.e., NB-IoT RAT), a bitmap indicating whether to bar and information on whether to apply or skip the access barring for an exceptional service from a cell of an eNodeB  200  through MIB or SIB. 
     An application layer of the wireless device informs that a transmission of the exceptional data is required to a NAS layer. Then, the NAS layer setup an RRC establishment cause as exceptional data, and forwards the same to an RRC layer. 
     The RRC layer performs an access barring check, and determines whether to bar. 
     In the case that the cell uses the NB-IoT RAT, the RRC establishment cause is the MO exceptional data, and the access barring should not be skipped for the exceptional data, a result of the access barring check may represent that a network access for the exceptional data transmission is not barred. 
     II. Modification of Proposal 1 
     When an Application layer (or including IMS layer) of a CIoT device requests a call or a data transmission for mobile originating (MO) service to a NAS layer, the NAS layer of the CIoT device may setup a call type and an RRC establishment cause field for the MO service as below. 
     1) In the case that NAS signalling low priority indicator or Indicator for CIoT (e.g. NAS signalling CIoT (or NB-IOT) (priority) indicator) or indicator for exceptional data request is setup for the CIoT device by a network, 
     With respect to signaling such as Attach request message, Tracking Area Update (TAU)/Routing Area Update (RAU) request message, service request message, extended service request message, and data service request message, the CIoT device may 
     Setup the call type as (Mobile) originating signalling, “originating MMTEL voice for MMTEL voice”, “originating MMTEL video for MMTEL video”, “originating SMSoIP for SMS over IP”, or “originating SMS for SMS over NAS”. And, 
     Setup the RRC establishment cause field as MO signalling. 
     2) In the case that NAS signalling low priority indicator or Indicator for CIoT (e.g. NAS signalling CIoT (or NB-IOT) (priority) indicator) or indicator for exceptional data request is setup for the CIoT device by a network, 
     With respect to (normal) call or data, the CIoT device may 
     Setup the call type as (Mobile) originating calls, “originating MMTEL voice for MMTEL voice”, “originating MMTEL video for MMTEL video”, “originating SMSoIP for SMS over IP”, or “originating SMS for SMS”. And, 
     Setup the RRC establishment cause field as MO data. 
     3) With respect to Mobile Terminate (MT) service, the CIoT device may 
     Setup the call type as (Mobile) terminating calls. And 
     Setup the RRC establishment cause field as MT access. 
     4) In the case that NAS signalling low priority indicator or Indicator for CIoT is not setup for the CIoT device by a network; or in the case that Overriding NAS signalling low priority indicator or Overriding Indicator for CIoT is setup for the CIoT device by a network, 
     With respect to call, data or signaling for (urgent data, exceptional data), the CIoT device 
     Setup the call type as call type: (Mobile) originating exception (or MO exception calls) or (Mobile) originating calls or (Mobile) originating signalling. And 
     Setup the RRC establishment cause field as MO exception (or MO exception data, MO exception signalling, etc.). 
     Here, it may be determined whether the CIoT device is setup with the NAS signalling low priority indicator or Indicator for CIoT or new indicator for exceptional data request by a network and whether the CIoT device is setup with the Overriding NAS signalling low priority indicator or Overriding Indicator for CIoT according to whether the application layer provides information/indicator to the NAS layer. 
     Meanwhile, even in the case of the mobile originating exceptional service, the NAS layer may setup the RRC establishment cause field and the call type normally as previously and forward the same to the AS layer. Then, when the AS layer (i.e., RRC layer) identifies the RAT for a CIoT service or a CIoT service through the information provided through SIB or MIB from the network or the information/indication separately provided from the NAS layer, the AS layer (i.e., RRC layer) may substitute/change the RRC establishment cause field received from the NAS layer to MO exception, and then, perform the barring check for access control. 
     Meanwhile, in the case that NAS signalling low priority indicator is setup for the CIoT device by a network, the AS layer (i.e., RRC layer) may substitute/change the RRC establishment cause field setup as “Delaytolerant” to “MO data”. In addition, in the case that (new) indication/information is setup for the CIoT device by a network for Overriding NAS signalling low priority indicator or exceptional data (or exceptional call or exceptional signaling), the AS layer (i.e., RRC layer) may substitute/change the RRC establishment cause field setup as “Delaytolerant” to “MO exception”. 
     The modification of proposal 1 is summarized as below. 
     The mobile originating (MO) exception for MO data and CIoT may be distinguished with each other as below. 
     MO call type+low priority indicator=MO data 
     MO call type=MO exception 
     The other contents are the same as the contents of proposal 1 described above, and accordingly, not described repeatedly, but the contents of proposal 1 is applied correspondingly. 
     III. Proposal 2 
     In a state in which an indicator indicating that the access control for CIoT is applied to the CIoT device (or UE) (e.g., Access control for CIoT Indicator) is setup, when an application layer (or including IMS layer) of the CIoT device requests a MO call or data to a NAS layer (i.e., RRC layer), the NAS layer provides an indication of the meaning to apply the access control for CIoT to the AS layer (i.e., RRC layer) when starting a NAS signaling request (Attach request, TAU/RAU request, service request, extended service request, and data service request, etc.) for data transmission. At this time the application layer may provide information/indication for distinguishing normal data and exceptional data to the NAS layer (i.e., RRC layer). 
     Only in the case that the AS layer (i.e., RRC layer) receives indication/information of the meaning to apply the access control for CIoT from the NAS layer, by using the information related to the access control for CIoT (e.g., Access control parameters for CIoT) provided from the network for the NAS signaling request through MIB or SIB, the AS layer (i.e., RRC layer) performs the barring check of the access control. At this time, the related information may include a bitmap for turning on/off whether to bar the access. Since the service for MO exceptional service (or exceptional data or exceptional signaling) is urgent data basically, in order to guarantee the RRC connection establishment or RRC connection reestablishment, the NAS layer may provide the indication for passing/skipping the barring check of the access control for the CIoT (or RRC establishment cause field configured as MO exception) to the AS layer (i.e., RRC layer) separately from the indication/information indicating to apply the access control for the CIoT. 
     The information related to the access control for CIoT provided from the network for the NAS signaling request through MIB or SIB may include a bitmap indicating on/off of barring. Here, since the exception service is for exceptional data (or exceptional call or exceptional signaling) basically, to guarantee the RRC connection establishment or RRC connection reestablishment, the bitmap may include information for skipping/passing the barring check for the access control of CIoT or information for turning off the barring check. In addition, information related to the access control for CIoT provided from the network for the NAS signaling request through MIB or SIB may include the information of turning on/off the skip/pass the barring check for the access control of CIoT (skip/pass=On/Off information/indication/flag, etc.) for the MO exceptional service. In this case, based on the information of turning on/off the skip/pass the barring check provided from the NAS layer, the AS layer (i.e., RRC layer) may determine whether to skip the barring check for the access control of CIoT. 
     Meanwhile, in the case of MO exceptional service, in the case that an indicator indicating that the CIoT service is supported (e.g., Indicator for CIoT) by the network and Overriding Indicator for CIoT (or Overriding NAS signalling CIoT) are set to the CIoT device, the CIoT device may skip the barring check of the access control for the request for the MO exceptional service. Or, NAS signalling low priority indicator is set to the CIoT device by the network and Overriding NAS signalling low priority indicator is set, the CIoT device (or UE) may skip/pass the barring check of the access control for the request for the MO exceptional service. 
     Meanwhile, a relation with other access control mechanism is described exemplarily. 
     III-1. EXAMPLE 1 
     For the MO exceptional service for exceptional data, when the CIoT device (or UE) receives the following configuration through an management object using OMA DM technique, 
     NAS signalling low priority indicator; 
     Override NAS signalling low priority indicator 
     The NAS layer of the CIoT device provides the indication/information of the meaning to apply the access control for CIoT, the indication/information for passing/skipping the barring check of the access control for the MO exceptional service (or RRC establishment cause field indicating MO exception) to the AS layer (i.e., RRC layer). At this time, the AS layer (i.e., RRC layer) does not setup the RRC establishment cause field as Delaytolerant or MO data, but setup as mo-exception. 
     Then, based on the provisions from the NAS layer and the indication/information for skipping the barring check for the MO exceptional service, the AS layer (i.e., RRC layer) determines whether to skip the barring check of the access control for CIoT. 
     Alternatively, the NAS layer sets the RRC establishment cause field as Delaytolerant or MO data and provides the same to the AS layer (i.e., RRC layer). Then, the AS layer (i.e., RRC layer) may set by substituting the RRC establishment cause field as mo-exception. And, based on the indication/information indicating skip/pass of the barring check of the access control of CIoT (skip/pass=On/Off information/indication/flag, etc.) provided from the network, the AS layer (i.e., RRC layer) determines whether to skip the barring check of the access control of CIoT. 
     Meanwhile, in the case that the network supports a CIoT service, the network may inform the information indicating the RAT that supports the CIoT service to the CIoT device (or UE) through SIB or MIB. When the AS layer (i.e., RRC layer) of the CIoT device (or UE) receives such information, the AS layer (i.e., RRC layer) may forward the same to the NAS layer (i.e., RRC layer). The contents described above may operate when the CIoT device receives the information or regardless of reception of the information. 
     On the other hand, even in the case that the CIoT device (or UE) roams to a visit network, in order to apply the contents described above, the visit network may forward (separate/additional) configuration/indicator/information for the process of the mobile originating exceptional service, NAS configuration management object or new configuration management object to the CIoT device. At this time, the case that configuration/indicator/information is set to 0 means the operation according to the contents described above in the roaming situation is not supported/performed, and the case that configuration/indicator/information is set to 1 means the operation according to the contents described above in the roaming situation is supported/performed. Such configuration/indicator/information may be determined by policy/configuration of a network provider or subscriber information, and the like. 
     III-2. EXAMPLE 2 
     For the MO exceptional service for exceptional data, when the CIoT device (or UE) receives the following configuration through an management object using OMA DM technique, 
     NAS signalling low priority indicator; 
     indicator for exceptional data request 
     The NAS layer provides the indication/information of the meaning to apply the access control for CIoT, the indication/information for passing/skipping the barring check of the access control for the MO exceptional service (or RRC establishment cause field indicating MO exception) to the AS layer (i.e., RRC layer). At this time, the AS layer (i.e., RRC layer) does not setup the RRC establishment cause field as Delaytolerant or MO data, but setup as mo-exception. 
     Then, based on the provisions from the NAS layer and the indication/information for skipping the barring check for the MO exceptional service, the AS layer (i.e., RRC layer) determines whether to skip the barring check of the access control for CIoT. 
     Alternatively, the NAS layer sets the RRC establishment cause field as Delaytolerant or MO data and provides the same to the AS layer (i.e., RRC layer). Then, the AS layer (i.e., RRC layer) may set by substituting the RRC establishment cause field as mo-exception. And, based on the indication/information indicating skip/pass of the barring check of the access control of CIoT (skip/pass=On/Off information/indication/flag, etc.) provided from the network, the AS layer (i.e., RRC layer) determines whether to skip the barring check of the access control of CIoT. 
     Meanwhile, in the case that the network supports a CIoT service, the network may inform the information indicating the RAT that supports the CIoT service to the CIoT device (or UE) through SIB or MIB. When the AS layer (i.e., RRC layer) of the CIoT device (or UE) receives such information, the AS layer (i.e., RRC layer) may forward the same to the NAS layer (i.e., RRC layer). The contents described above may operate when the CIoT device receives the information or regardless of reception of the information. 
     On the other hand, even in the case that the CIoT device (or UE) roams to a visit network, in order to apply the contents described above, the visit network may forward (separate/additional) configuration/indicator/information for the process of the mobile originating exceptional service, NAS configuration management object or new configuration management object to the CIoT device. At this time, the case that configuration/indicator/information is set to 0 means the operation according to the contents described above in the roaming situation is not supported/performed, and the case that configuration/indicator/information is set to 1 means the operation according to the contents described above in the roaming situation is supported/performed. Such configuration/indicator/information may be determined by policy/configuration of a network provider or subscriber information, and the like. 
     III-3. EXAMPLE 3 
     For the MO exceptional service for exceptional data, when the CIoT device (or UE) receives the following configuration through an management object using OMA DM technique, 
     NAS signalling low priority indicator; 
     Override NAS signalling low priority indicator; 
     (new) indicator for exceptional data request 
     The NAS layer provides the indication/information of the meaning to apply the access control for CIoT, the indication/information for passing/skipping the barring check of the access control for the MO exceptional service (or RRC establishment cause field indicating MO exception) to the AS layer (i.e., RRC layer). At this time, the AS layer (i.e., RRC layer) does not setup the RRC establishment cause field as Delaytolerant or MO data, but setup as mo-exception. 
     Then, based on the provisions from the NAS layer and the indication/information for skipping the barring check for the MO exceptional service, the AS layer (i.e., RRC layer) determines whether to skip the barring check of the access control for CIoT. 
     Alternatively, the NAS layer sets the RRC establishment cause field as Delaytolerant or MO data and provides the same to the AS layer (i.e., RRC layer). Then, the AS layer (i.e., RRC layer) may set by substituting the RRC establishment cause field as mo-exception. And, based on the indication/information indicating skip/pass of the barring check of the access control of CIoT (skip/pass=On/Off information/indication/flag, etc.) provided from the network, the AS layer (i.e., RRC layer) determines whether to skip the barring check of the access control of CIoT. 
     Meanwhile, in the case that the network supports a CIoT service, the network may inform the information indicating the RAT that supports the CIoT service to the CIoT device (or UE) through SIB or MIB. When the AS layer (i.e., RRC layer) of the CIoT device (or UE) receives such information, the AS layer (i.e., RRC layer) may forward the same to the NAS layer (i.e., RRC layer). The contents described above may operate when the CIoT device receives the information or regardless of reception of the information. 
     On the other hand, even in the case that the CIoT device (or UE) roams to a visit network, in order to apply the contents described above, the visit network may forward (separate/additional) configuration/indicator/information for the process of the mobile originating exceptional service, NAS configuration management object or new configuration management object to the CIoT device. At this time, the case that configuration/indicator/information is set to 0 means the operation according to the contents described above in the roaming situation is not supported/performed, and the case that configuration/indicator/information is set to 1 means the operation according to the contents described above in the roaming situation is supported/performed. Such configuration/indicator/information may be determined by policy/configuration of a network provider or subscriber information, and the like. 
     The contents of proposal 2 are summarized as below. 
     The CIoT device may skip the barring check of the access control for the MO exception. 
     The network may broadcast the information related to the access control for a CIoT service through MIB or SIB. 
     When the NAS layer indicates a call type and a mobile originating exception, the RRC layer of the CIoT device may determine whether to skip the barring check of the access control for the RRC connection establishment and the RRC connection reestablishment. 
     The NAS layer may provide an indication on whether to skip the barring check of the access control for the MO exception. 
     The contents of proposal 2 and the examples are summarized as below. 
       FIG. 13  is a signal flowchart illustrating proposal 2 of the present specification schematically. 
     As illustrated, a wireless device receives information informing the RAT that supports a CIoT service (i.e., NB-IoT RAT), a bitmap indicating whether to bar and information on whether to apply or skip the access barring for an exceptional service from a cell of an eNodeB  200  through MIB or SIB. 
     An application layer of the wireless device informs that a transmission of the exceptional data is required to a NAS layer. Then, the NAS layer setup an RRC establishment cause as exceptional data, and forwards the same to an RRC layer. In addition, the NAS layer forwards the indication of skipping/passing the barring check for the exceptional data to the RRC layer. 
     Then, the RRC layer does not perform the barring check for the exceptional data, but skips the same, and transmits an RRC connection request message accordingly. 
     IV. Proposal 3 
     When NAS signalling low priority indicator and indication/information indicating MO exception for exceptional data are set together, the CIoT device (or UE) selects only one RRC establishment cause field according to an accessed RAT, and accordingly, performs the barring check for the access control. 
     1) A case that the RAT to which the CIoT device (or UE) accesses currently is the RAT for NB-IoT, 
     1-A) The NAS layer of the CIoT device (or UE) sets the RRC establishment cause field as one of mo-data, mo-signalling, mo-exception and mt-access, and provides the same to the AS layer (i.e., RRC layer). That is, the NAS layer does not set the RRC establishment cause field as “Delaytolerant”. Then, based on the RRC establishment cause field and the call type provided from the NAS layer and the information related to the access control for CIoT provided from the network, the AS (RRC) may determine whether to skip the barring check of the access control. 
     1-B) Or, the NAS layer of the CIoT device (or UE) sets the RRC establishment cause field as one of mo-data, mo-signalling, mo-exception and mt-access, and then, forwards the same to the AS layer (i.e., RRC layer) together with the call type. In addition, the NAS layer forwards the indication/information indicating a transmission of exceptional data to the AS layer (i.e., RRC layer) additionally. 
     In the case that the RRC establishment cause field received from the NAS layer is set as Delaytolerant, the AS layer (i.e., RRC layer) substitutes and sets the RRC establishment cause field as the mo-data. In the case that the RRC establishment cause field received from the NAS layer is set as mo-data or Delaytolerant with exception data, the AS layer substitutes and sets the RRC establishment cause field as the mo-exception. In addition, the AS layer performs the barring check of the access control based on the information related to the access control for CIoT provided from the network. Meanwhile, in the case that the RRC establishment cause field is mo-exception, based on the related information provided from the network through MIB or SIB, the AS layer may skip the barring check of the access control. 
     2) A case that the RAT to which the CIoT device (or UE) accesses currently is normal RAT (i.e., EUTRA), 
     2-A) The NAS layer of the CIoT device (or UE) sets the RRC establishment cause field as one of mo-data, mo-signalling, Delaytolerant and mt-access, and provides the same to the AS layer (i.e., RRC layer) together with the call type. At this time, the RRC establishment cause field “mo-exception” is not used. 
     Then, based on the RRC establishment cause field and the call type provided from the NAS layer and the information related to the access control for CIoT provided from the network, the AS (RRC) performs the barring check of the access control. 
     2-B) The NAS layer of the CIoT device (or UE) sets the RRC establishment cause field as one of mo-data, mo-signalling, Delaytolerant and mt-access, and then, forwards the same to the AS layer (i.e., RRC layer) together with the call type. In addition, the NAS layer forwards the indication/information indicating a transmission of exceptional data to the AS layer (i.e., RRC layer) additionally. 
     Then, based on the RRC establishment cause field and the call type provided from the NAS layer and the information related to the access control for CIoT provided from the network, the AS (RRC) performs the barring check of the access control. 
     In the case that the RRC establishment cause field received from the NAS layer is set as mo-data or Delaytolerant with exception data, the AS layer substitutes it by mo-data or Delaytolerant. And, the AS layer performs the barring check of the access control based on the information related to the access control for CIoT provided from the network. In addition, in the case that the AS layer receives an indication for MO exception, based on the related information provided from the network through MIB and/or SIB and the indication/information provided from the NAS layer, the AS layer may determine whether to skip the barring check of the access control. The related information provided from the network through or the indication/information provided from the NAS layer may include information indicating skip of the barring check according to ACB, skip of barring check according to EAB or skip of barring check according to ACDC. 
     Meanwhile, in the case that NAS signalling low priority indicator and indication/information indicating MO exception for exceptional data are set to the CIoT device (or UE) together, according to the accessed RAT (or according to CIoT device (or UE) capability, network capability or network policy), after disabling one of the configurations, the CIoT device (or UE) may perform the check of the access control by using the RRC establishment cause field. In this case, invention method 1-A), 1-B), 2-A) and 2-B) of proposal 3 of the present invention described above may be applied with being combined with each other. 
     Otherwise, in the case that NAS signalling low priority indicator and/or Override NAS signalling low priority indicator and/or indication/information indicating MO exception for exceptional data (or call or signaling) are set to the CIoT device (or UE), based on the currently accessed RAT (or according to CIoT device capability, network capability or network policy), after disabling one of the configurations, the CIoT device (or UE) may perform or skip the barring check of the access control by using the RRC establishment cause field. In this case, invention method 1-A), 1-B), 2-A) and 2-B) of proposal 3 of the present invention described above may be applied with being combined with each other. 
     In proposal 1, proposal 2 and proposal 3 described above, in the case that Override NAS signalling low priority indicator is set to the CIoT device (or UE) by the network, the CIoT device (or UE) may set Device properties Information Element in the NAS signaling request message (e.g., Attach request message, TAU request message, service request message, extended service request message, and data service request message, etc.) to “MS is not configured for NAS signalling low priority”. In addition, NAS signalling low priority indicator is set to the CIoT device (or UE) by the network, the CIoT device (or UE) may set Device properties Information Element in the NAS signaling message to “MS is configured for NAS signalling low priority”. 
     Meanwhile, in proposal 1, proposal 2 and proposal 3 of the present invention: 
     (i) In the case that an indicator indicating that a CIoT service is supported (i.e., Indicator for CIoT) is set to the CIoT device (or UE) by the network, the CIoT device (or UE) may set Device properties Information Element (or new Information Element) in the NAS signaling request message to “MS is configured for NAS signalling for CIoT (or NB-IoT)”. When an MME receives the NAS signaling request message, the MME may reject the NAS signaling request in network congested/overload situation. In the case of rejecting it, the MME may forward a cause value in the rejection message with #22 or a new value to the CIoT device. In addition, in this case, for congestion/overload control, the MME may include a back-off timer (e.g., T3346 timer for mobility management for each UE, T3396 timer for session management for each APN and each UE, and a new timer for mobility management for each UE or a new timer for session management for each APN and each UE). When receiving the rejection message, the CIoT device (or UE) drives a timer according to the back-off timer value, and does not transmit the NAS signaling request message until the timer expires. In the case that the back-off timer value is not included in the rejection message, the CIoT device drives a timer according to the default value (e.g., 30 sec, 30 minutes or 1 hour, etc.). 
     (ii) In the case that a new indicator indicating MO exception for exceptional data is set to the CIoT device (or UE) by the network, the CIoT device (or UE) may set Device properties Information Element (or new Information Element) in the NAS signaling request message to “MS is configured for NAS signalling for CIoT (or NB-IoT)” or “MS is configured for exceptional data request/report”. At this time, the MME may reject the NAS signaling request in network congested/overload situation, this is the same as described above. 
     In (i) and (ii) described above, in the case that NAS signalling low priority indicator is set to the CIoT device (or UE) by the network, (i) the indicator indicating that a CIoT service is supported (i.e., Indicator for CIoT) and (ii) the new indicator indicating MO exception for exceptional data are ignored, and based on the existing NAS signalling low priority indicator and/or Override NAS signalling low priority indicator, the CIoT device (or UE) and the network may drive the existing access control and the back-off timer. Instead, (i) the indicator indicating that a CIoT service is supported (i.e., Indicator for CIoT) and (ii) the new indicator indicating MO exception for exceptional data may be applied and operated only for performing the access control for CIoT proposed in the present specification. 
     Alternatively, in the case that NAS signalling low priority indicator is set to the CIoT device (or UE) by the network, based on (i) the indicator indicating that a CIoT service is supported (i.e., Indicator for CIoT) and (ii) the new indicator indicating MO exception for exceptional data, the CIoT device (or UE) may also perform the access control for CIoT. At this time, the CIoT device (or UE) and the network may ignore the existing access control and the back-off timer. 
     The proposals described above may be used in combination. 
     The contents described so far may be implemented by hardware. This is described by referring to accompanying drawing. 
       FIG. 14  is a block diagram illustrating a configuration of a wireless device  100  and a base station  200  according to an embodiment of the present invention. 
     As shown in  FIG. 14 , the wireless device  100  includes a storage means  101 , a controller  102  and a transceiver unit  103 . And the base station  200  includes a storage means  201 , a controller  202  and a transceiver unit  203 . 
     The storage means  101  and  201  store the method described above. 
     The controllers  102  and  202  control the storage means  101  and  201  and the transceiver units  103  and  203 . Particularly, the controllers  102  and  202  perform the methods stored in the storage means  101  and  201 . And the controllers  102  and  202  transmit the signals described above through the transceiver units  103  and  203 . 
     So far, the preferred embodiments of the present invention are described as an example, but the scope of the present invention is not limited to a specific embodiment. Accordingly, the present invention may be modified, changed or improved in various forms within the scope written in the inventive concept and the claims.