WO2018066922A1

WO2018066922A1 - Method for performing validity check of system information block, and apparatus supporting same

Info

Publication number: WO2018066922A1
Application number: PCT/KR2017/010947
Authority: WO
Inventors: 김상원; 이영대
Original assignee: 엘지전자 주식회사
Priority date: 2016-10-03
Filing date: 2017-09-29
Publication date: 2018-04-12

Abstract

Disclosed are a method for performing, by a terminal, a validity check of a system information block (SIB) in a wireless communication system, and an apparatus supporting the same. The method comprises the steps of: storing system information blocks received from a serving cell; receiving, from a current serving cell, validity check information for checking the validity of the stored system information blocks; and performing a validity check of the system information block by comparing the validity check information with a validity area of each of the stored system information blocks, version information of the stored system information blocks, and a version-specific index that instructs the update status of each version, respectively.

Description

How to perform system information block validation and devices that support it

The terminal relates to a technique for performing a validity check on each of the stored system information blocks.

Efforts have been made to develop an improved 5th-generation (5G) communication system or a pre-5G communication system to meet the increasing demand for wireless data traffic since the commercialization of a 4th-generation (4G) communication system. For this reason, a 5G communication system or a pre-5G communication system is called a system after a 4G network (beyond 4G network) or after a long term evolution (LTE) system (post LTE).

On the other hand, as the amount of data communication increases, On-demand System Information (OSI) has been proposed. In the case of on-demand system information, the terminal may request system information from the cell, and the network receiving the request may transmit the requested system information to the terminal. As such, there is a continuous discussion for efficiently using radio resources.

Research on how to use valid system information as it is to efficiently use radio resources. Specifically, when the serving cell changes as the terminal moves, the existing system information may also be used in the new serving cell. At this time, the terminal should determine whether to use the existing system information block in the new serving cell or request new service information to the network.

Furthermore, even if the serving cell is not changed, when some system information blocks are updated, the terminal should determine whether the system information blocks currently held are valid. In this case, the terminal may perform an update only for an invalid system information block.

According to an embodiment of the present invention, in a method in which a terminal performs a validity check of a system information block (SIB) in a wireless communication system, storing a system information block received from a serving cell step; Receiving validation information for validating the stored system information block from a current serving cell; And validity checking of the system information block by comparing a validity area for each stored system information block, version information of the stored system information block, and a version index indicating the update status of each version with the validation information. Provided is a method comprising performing a step.

The validity check information may include information regarding a cell ID of a current serving cell, a version of a system information block considered to be valid, and the index for each version.

The performing of the validation check may include the cell ID in a cell list of a valid area of the stored system information block, a version of the stored system information block and a version included in the validation information, and the stored When the version index of the system information block and the version index included in the validity check information are the same, the terminal may determine that the stored system information block is valid.

The performing of the validation check may include that the cell ID is not included in the cell list of the valid region of the stored system information block, the version of the stored system information block is not the same as the version included in the validation information, or Alternatively, when the version index of the stored system information block and the version index included in the validity check information are not the same, the terminal may determine that the stored system information block is invalid.

If it is determined that the stored system information block is invalid, the method may further include discarding the stored system information block.

The performing of the validity checking may include comparing a value tag of the stored system information block with a value tag included in the validation information, wherein the system information block is determined to be invalid, and the stored system If the value tag of the information block and the value tag included in the validation information are the same and the cell ID is not included in the cell list of the valid region of the stored system information block, the terminal retains the stored system information block as it is. can do.

The method may further include requesting transmission of a new system information block for the discarded system information to a current serving cell.

The method may further include receiving valid timer setting information for each system information block from the serving cell.

The performing of the validity check may include determining that the validity timer is not valid for the expired system information block.

According to another embodiment of the present invention, a terminal for validating a system information block in a wireless communication system, the terminal comprising: a memory; Transceiver; And a processor connecting the memory and the transceiver, wherein the processor stores a system information block received from a serving cell and receives validation information for validating the stored system information block from a current serving cell. And storing the stored system information block by comparing a validity area for each stored system information block, version information of the stored system information block, and a version-specific index indicating an update status of each of the versions with the validation information, respectively. A terminal is provided, which is configured to perform a validity check of.

The processor may include the cell ID in a cell list of a valid area of the stored system information block, a version of the stored system information block is the same as a version included in the validation information, and a version of the stored system information block. If the per-index and the per-version index included in the validity check information are the same, the terminal may be configured to determine that the stored system information block is valid.

The processor may not include the cell ID in the cell list of the valid region of the stored system information block, or the version of the stored system information block is not the same as the version included in the validity check information, or the stored system information. If the version-specific index of the block and the version-specific index included in the validity check information are not the same, the terminal may be configured to determine that the stored system information block is invalid.

If it is determined that the stored system information block is invalid, the processor may be configured to discard the stored system information block.

The processor is configured to perform the validation by comparing the value tag of the stored system information block with the value tag included in the validation information, and determines that the system information block is not valid, but the stored system information. If the value tag of the block and the value tag included in the validation information are the same and the cell ID is not included in the cell list of the valid region of the stored system information block, the processor retains the stored system information block as it is. It can be configured to.

The terminal may save radio resources by not updating or receiving all system information or updating or receiving only invalid system information.

1 shows a structure of an LTE system.

2 shows an air interface protocol of an LTE system for a control plane.

3 shows an air interface protocol of an LTE system for a user plane.

4 shows the structure of a 5G system.

5 shows an example in which a master information block (MIB), a system information block (SIB1), and other system information blocks (SIB) are transmitted.

6 shows an update of system information.

7 is a flowchart illustrating a method of performing system information validation according to an embodiment of the present invention.

8 is a flowchart illustrating a method of performing system information validation according to an embodiment of the present invention.

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

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various wireless communication systems. CDMA may be implemented with a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented by wireless technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), and the like. IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e. UTRA is part of a universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is part of evolved UMTS (E-UMTS) using evolved-UMTS terrestrial radio access (E-UTRA), which employs OFDMA in downlink and SC in uplink -FDMA is adopted. LTE-A (advanced) is the evolution of 3GPP LTE. 5G communication system is the evolution of LTE-A.

For clarity, the following description focuses on LTE-A / 5G, but the technical spirit of the present invention is not limited thereto.

1 shows a structure of an LTE system. Communication networks are widely deployed to provide various communication services such as IMS and Voice over internet protocol (VoIP) over packet data.

Referring to FIG. 1, an LTE system structure includes one or more UEs 10, an evolved-UMTS terrestrial radio access network (E-UTRAN), and an evolved packet core (EPC). The terminal 10 is a communication device moved by a user. The terminal 10 may be fixed or mobile and may be called by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), and a wireless device.

The E-UTRAN may include one or more evolved node-eB (eNB) 20, and a plurality of terminals may exist in one cell. The eNB 20 provides an end point of a control plane and a user plane to the terminal. The eNB 20 generally refers to a fixed station communicating with the terminal 10, and may be referred to in other terms such as a base station (BS), a base transceiver system (BTS), an access point, and the like. . One eNB 20 may be arranged per cell. There may be one or more cells within the coverage of the eNB 20. One cell may be configured to have one of bandwidths such as 1.25, 2.5, 5, 10, and 20 MHz to provide downlink (DL) or uplink (UL) transmission service to various terminals. In this case, different cells may be configured to provide different bandwidths.

Hereinafter, DL means communication from the eNB 20 to the terminal 10, and UL means communication from the terminal 10 to the eNB 20. In the DL, the transmitter may be part of the eNB 20 and the receiver may be part of the terminal 10. In the UL, the transmitter may be part of the terminal 10 and the receiver may be part of the eNB 20.

The EPC may include a mobility management entity (MME) that serves as a control plane and a serving gateway (S-GW) that serves as a user plane. The MME / S-GW 30 may be located at the end of the network and is connected to an external network. The MME has information about the access information of the terminal or the capability of the terminal, and this information may be mainly used for mobility management of the terminal. S-GW is a gateway having an E-UTRAN as an endpoint. The MME / S-GW 30 provides the terminal 10 with the endpoint of the session and the mobility management function. The EPC may further include a packet data network (PDN) -gateway (GW). PDN-GW is a gateway with PDN as an endpoint.

The MME includes non-access stratum (NAS) signaling to the eNB 20, NAS signaling security, access stratum (AS) security control, inter CN (node network) signaling for mobility between 3GPP access networks, idle mode terminal reachability ( Control and execution of paging retransmission), tracking area list management (for terminals in idle mode and active mode), P-GW and S-GW selection, MME selection for handover with MME change, 2G or 3G 3GPP access Bearer management, including roaming, authentication, and dedicated bearer settings, SGSN (serving GPRS support node) for handover to the network, public warning system (ETWS) and commercial mobile alarm system (PWS) It provides various functions such as CMAS) and message transmission support. S-GW hosts can be based on per-user packet filtering (eg, through deep packet inspection), legal blocking, terminal IP (Internet protocol) address assignment, transport level packing marking in DL, UL / DL service level charging, gating and It provides various functions of class enforcement, DL class enforcement based on APN-AMBR. For clarity, the MME / S-GW 30 is simply represented as a "gateway", which may include both MME and S-GW.

An interface for user traffic transmission or control traffic transmission may be used. The terminal 10 and the eNB 20 may be connected by the Uu interface. The eNBs 20 may be interconnected by an X2 interface. Neighboring eNBs 20 may have a mesh network structure by the X2 interface. The eNBs 20 may be connected with the EPC by the S1 interface. The eNBs 20 may be connected to the EPC by the S1-MME interface and may be connected to the S-GW by the S1-U interface. The S1 interface supports a many-to-many-relation between eNB 20 and MME / S-GW 30.

The eNB 20 may select for the gateway 30, routing to the gateway 30 during radio resource control (RRC) activation, scheduling and transmission of paging messages, scheduling channel information (BCH), and the like. Perform connection mobility control in transmission, dynamic allocation of resources from the UL and DL to the terminals 10, configuration and provisioning of eNB measurements, radio bearer control, radio admission control (RAC) and LTE activation can do. As mentioned above, the gateway 30 may perform paging initiation, LTE idle state management, user plane encryption, SAE bearer control, and encryption and integrity protection functions of NAS signaling in the EPC.

2 shows an air interface protocol of an LTE system for a control plane. 3 shows an air interface protocol of an LTE system for a user plane.

The layer of the air interface protocol between the UE and the E-UTRAN is based on the lower three layers of the open system interconnection (OSI) model, which is well known in communication systems, and includes L1 (first layer), L2 (second layer), and L3 (third layer). Hierarchical). The air interface protocol between the UE and the E-UTRAN may be horizontally divided into a physical layer, a data link layer, and a network layer, and vertically a protocol stack for transmitting control signals. ) Can be divided into a control plane and a user plane which is a protocol stack for transmitting data information. Layers of the radio interface protocol may exist in pairs in the UE and the E-UTRAN, which may be responsible for data transmission of the Uu interface.

The physical layer (PHY) belongs to L1. The physical layer provides an information transmission service to a higher layer through a physical channel. The physical layer is connected to a higher layer of a media access control (MAC) layer through a transport channel. Physical channels are mapped to transport channels. Data may be transmitted between the MAC layer and the physical layer through a transport channel. Data between different physical layers, that is, between the physical layer of the transmitter and the physical layer of the receiver may be transmitted using radio resources through a physical channel. The physical layer may be modulated using an orthogonal frequency division multiplexing (OFDM) scheme, and utilizes time and frequency as radio resources.

The physical layer uses several physical control channels. A physical downlink control channel (PDCCH) reports resource allocation of a paging channel (PCH) and a downlink shared channel (DL-SCH), and hybrid automatic repeat request (HARQ) information related to the DL-SCH to the UE. The PDCCH may carry an uplink grant to report to the UE regarding resource allocation of uplink transmission. The physical control format indicator channel (PCFICH) informs the UE of the number of OFDM symbols used for the PDCCH and is transmitted every subframe. A physical hybrid ARQ indicator channel (PHICH) carries a HARQ ACK (non-acknowledgement) / NACK (non-acknowledgement) signal for UL-SCH transmission. A physical uplink control channel (PUCCH) carries UL control information such as HARQ ACK / NACK, a scheduling request, and a CQI for downlink transmission. The physical uplink shared channel (PUSCH) carries an uplink shared channel (UL-SCH).

The physical channel includes a plurality of subframes in the time domain and a plurality of subcarriers in the frequency domain. One subframe consists of a plurality of symbols in the time domain. One subframe consists of a plurality of resource blocks (RBs). One resource block is composed of a plurality of symbols and a plurality of subcarriers. In addition, each subframe may use specific subcarriers of specific symbols of the corresponding subframe for the PDCCH. For example, the first symbol of the subframe may be used for the PDCCH. The PDCCH may carry dynamically allocated resources, such as a physical resource block (PRB) and modulation and coding schemes (MCS). A transmission time interval (TTI), which is a unit time at which data is transmitted, may be equal to the length of one subframe. One subframe may have a length of 1 ms.

The transport channel is classified into a common transport channel and a dedicated transport channel depending on whether the channel is shared or not. A DL transport channel for transmitting data from a network to a UE includes a broadcast channel (BCH) for transmitting system information, a paging channel (PCH) for transmitting a paging message, and a DL-SCH for transmitting user traffic or control signals. And the like. The DL-SCH supports dynamic link adaptation and dynamic / semi-static resource allocation by varying HARQ, modulation, coding and transmit power. In addition, the DL-SCH may enable the use of broadcast and beamforming throughout the cell. System information carries one or more system information blocks. All system information blocks can be transmitted in the same period. Traffic or control signals of a multimedia broadcast / multicast service (MBMS) are transmitted through a multicast channel (MCH).

The UL transport channel for transmitting data from the terminal to the network includes a random access channel (RAC) for transmitting an initial control message, a UL-SCH for transmitting user traffic or a control signal, and the like. The UL-SCH can support dynamic link adaptation due to HARQ and transmit power and potential changes in modulation and coding. In addition, the UL-SCH may enable the use of beamforming. RACH is generally used for initial connection to a cell.

The MAC layer belonging to L2 provides a service to a radio link control (RLC) layer, which is a higher layer, through a logical channel. The MAC layer provides a mapping function from a plurality of logical channels to a plurality of transport channels. The MAC layer also provides a logical channel multiplexing function by mapping from multiple logical channels to a single transport channel. The MAC sublayer provides data transfer services on logical channels.

The logical channel may be divided into a control channel for information transmission in the control plane and a traffic channel for information transmission in the user plane according to the type of information to be transmitted. That is, a set of logical channel types is defined for other data transfer services provided by the MAC layer. The logical channel is located above the transport channel and mapped to the transport channel.

The control channel is used only for conveying information in the control plane. The control channel provided by the MAC layer includes a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and a dedicated control channel (DCCH). BCCH is a downlink channel for broadcasting system control information. PCCH is a downlink channel used for transmitting paging information and paging a terminal whose cell-level location is not known to the network. CCCH is used by the terminal when there is no RRC connection with the network. MCCH is a one-to-many downlink channel used to transmit MBMS control information from the network to the terminal. DCCH is a one-to-one bidirectional channel used by the terminal for transmitting dedicated control information between the terminal and the network in an RRC connection state.

The traffic channel is used only for conveying information in the user plane. The traffic channel provided by the MAC layer includes a dedicated traffic channel (DTCH) and a multicast traffic channel (MTCH). DTCH is used for transmission of user information of one UE in a one-to-one channel and may exist in both uplink and downlink. MTCH is a one-to-many downlink channel for transmitting traffic data from the network to the terminal.

The uplink connection between the logical channel and the transport channel includes a DCCH that can be mapped to the UL-SCH, a DTCH that can be mapped to the UL-SCH, and a CCCH that can be mapped to the UL-SCH. The downlink connection between the logical channel and the transport channel is a BCCH that can be mapped to a BCH or DL-SCH, a PCCH that can be mapped to a PCH, a DCCH that can be mapped to a DL-SCH, a DTCH that can be mapped to a DL-SCH, MCCH that can be mapped to MCH and MTCH that can be mapped to MCH.

The RLC layer belongs to L2. The function of the RLC layer includes adjusting the size of the data by segmentation / concatenation of the data received from the upper layer in the radio section such that the lower layer is suitable for transmitting data. In order to guarantee the various QoS required by the radio bearer (RB), the RLC layer is divided into three modes: transparent mode (TM), unacknowledged mode (UM) and acknowledged mode (AM). Provides three modes of operation. AM RLC provides retransmission through automatic repeat request (ARQ) for reliable data transmission. Meanwhile, the function of the RLC layer may be implemented as a functional block inside the MAC layer, in which case the RLC layer may not exist.

The packet data convergence protocol (PDCP) layer belongs to L2. The PDCP layer introduces an IP packet, such as IPv4 or IPv6, over a relatively low bandwidth air interface to provide header compression that reduces unnecessary control information so that the transmitted data is transmitted efficiently. Header compression improves transmission efficiency in the wireless section by transmitting only the information necessary for the header of the data. In addition, the PDCP layer provides security. Security functions include encryption to prevent third party inspection and integrity protection to prevent third party data manipulation.

The radio resource control (RRC) layer belongs to L3. The RRC layer at the bottom of L3 is defined only in the control plane. The RRC layer serves to control radio resources between the terminal and the network. To this end, the UE and the network exchange RRC messages through the RRC layer. The RRC layer is responsible for the control of logical channels, transport channels and physical channels in connection with the configuration, re-configuration and release of RBs. RB is a logical path provided by L1 and L2 for data transmission between the terminal and the network. That is, RB means a service provided by L2 for data transmission between the UE and the E-UTRAN. Setting up an RB means defining the characteristics of the radio protocol layer and channel to provide a particular service, and determining each specific parameter and method of operation. RBs may be classified into two types: signaling RBs (SRBs) and data RBs (DRBs). The SRB is used as a path for transmitting RRC messages in the control plane, and the DRB is used as a path for transmitting user data in the user plane.

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

Referring to FIG. 2, the RLC and MAC layers (end at the eNB at the network side) may perform functions such as scheduling, ARQ and HARQ. The RRC layer (ended at the eNB at the network side) may perform functions such as broadcast, paging, RRC connection management, RB control, mobility function, and UE measurement report / control. The NAS control protocol (terminated at the gateway's MME at the network side) may perform functions such as SAE bearer management, authentication, LTE_IDLE mobility handling, paging initiation at LTE_IDLE, and security control for signaling between the terminal and the gateway.

Referring to FIG. 3, the RLC and MAC layer (end at the eNB at the network side) may perform the same function as the function in the control plane. The PDCP layer (terminating at the eNB at the network side) may perform user plane functions such as header compression, integrity protection and encryption.

이하, 5G 네트워크 구조에 대하여 설명한다.Hereinafter, the 5G network structure will be described.

4 shows the structure of a 5G system.

In the case of an Evolved Packet Core (EPC), which is a core network structure of an existing Evolved Packet System (EPS), an entity such as a mobility management entity (MME), a serving gateway (S-GW), and a packet data network gateway (P-GW) Each function, reference point, protocol, etc. are defined.

On the other hand, in the case of a 5G core network (or NextGen core network), functions, reference points, protocols, etc. are defined for each network function (NF). That is, 5G core network does not define functions, reference points, protocols, etc. for each entity.

Referring to FIG. 4, the 5G system structure includes one or more UEs 10, a Next Generation-Radio Access Network (NG-RAN), and a Next Generation Core (NGC).

The NG-RAN may include one or more gNBs 40, and a plurality of terminals may exist in one cell. The gNB 40 provides the terminal with the control plane and the end point of the user plane. The gNB 40 generally refers to a fixed station communicating with the terminal 10 and may be referred to as other terms such as a base station (BS), a base transceiver system (BTS), an access point, and the like. . One gNB 40 may be arranged per cell. There may be one or more cells within coverage of the gNB 40.

The NGC may include an Access and Mobility Function (AMF) and a Session Management Function (SMF) that are responsible for the functions of the control plane. The AMF may be responsible for the mobility management function, and the SMF may be responsible for the session management function. The NGC may include a user plane function (UPF) that is responsible for the function of the user plane.

An interface for user traffic transmission or control traffic transmission may be used. Terminal 10 and gNB 40 may be connected by an NG3 interface. The gNBs 40 may be interconnected by Xn interface. Neighboring gNBs 40 may have a mesh network structure with an Xn interface. The gNBs 40 may be connected to the NGC by the NG interface. The gNBs 40 may be connected to the AMF by the NG-C interface and may be connected to the UPF by the NG-U interface. The NG interface supports a many-to-many-relation between gNB 40 and MME / UPF 50.

The gNB host may determine functions for radio resource management, IP header compression and encryption of user data stream, and routing to AMF from information provided by the terminal. Selection of an AMF at UE attachment when no routing to an AMF can be determined from the information provided by the UE, Routing of User Plane data to one or more UPFs towards UPF (s)), Scheduling and transmission of paging messages (originated from the AMF), transmission and scheduling of system broadcast information (derived from AMF or O & M) Scheduling and transmission of system broadcast information (originated from the AMF or O & M), or setting up and measuring measurement reports for scheduling and mobility (Me It can perform functions such as asurement and measurement reporting configuration for mobility and scheduling.

Access and Mobility Function (AMF) hosts can be used for NAS signaling termination, NAS signaling security, AS Security control, and inter CN node signaling for mobility between 3GPP access networks. node signaling for mobility between 3GPP access networks), IDLE mode UE reachability (including control and execution of paging retransmission), UE in ACTIVE mode and IDLE mode Tracking Area list management (for UE in idle and active mode), AMF selection for handovers with AMF change, Access Authentication, Or perform key functions such as access authorization including check of roaming rights. The.

A user plane function (UPF) host is an anchor point for Intra- / Inter-RAT mobility (when applicable), an external PDU session point for the interconnection to the data network (if applicable). (External PDU session point of interconnect to Data Network), Packet routing & forwarding, Packet inspection and User plane part of Policy rule enforcement, Traffic usage reporting ( Traffic usage reporting, Uplink classifier to support routing traffic flows to a data network, Branching point to support multi- homed PDU session, QoS handling for the user plane, e.g. packet filtering, gating, QoS handling for user plane, eg packet filtering, gating, UL / DL rate enforcement, uplink traffic verification (SDF to QoS flow mapping), transport level packet marking in downlink and uplink It can perform main functions such as packet marking in the uplink and downlink, or downlink packet buffering and downlink data notification triggering.

The Session Management Function (SMF) host is responsible for session management, UE IP address allocation and management, selection and control of UP functions, and traffic to the appropriate destinations. Configure traffic steering at UPF to route traffic to proper destination, control part of policy enforcement and QoS, or downlink data notification Can perform key functions such as

이하, 시스템 정보(SI: system information)에 대하여 설명한다.Hereinafter, system information (SI) will be described.

The LTE cell broadcasts the basic parameters necessary for the operation of the IDLE_MODE terminal and the CONNECTED_MODE terminal into a plurality of information blocks. Examples of information blocks include MIBs, SIB1, SIB2, and other System Information Blocks (SIBn).

The MIB includes the most basic parameters necessary for the terminal to access the cell. Referring to FIG. 5, the MIB message is broadcasted through the BCH at a period of 40 ms, and MIB transmission is repeated in all radio frames within a 40 ms period. The terminal receives the SIB message using the parameter received from the MIB.

There are several types of SIBs.

SIB1 includes information related to cell access, and in particular, includes scheduling information of other SIBs SIB2 to SIBn except SIB1. SIBs having the same transmission period among other SIs except SIB1 are included in the same system information (SI) message and transmitted. Therefore, the scheduling information includes a mapping relationship between each SIB and SI message. The SI message is transmitted in a window of the time domain (SI-window), and each SI message is associated with one SI-window. Since SI-windows of different SIs do not overlap, only one SI message is transmitted in any SI-window. Therefore, the scheduling information includes the length of the SI-window and the SI transmission period. The time / frequency at which the SI message is transmitted is determined by the dynamic scheduling of the base station. SIB1 is broadcast on a downlink common channel (DL-SCH) in eight radio frame periods (ie, 80 ms periods), and SIB1 is repeatedly retransmitted on subframe 5 of a radio frame of SFN mod 2 within an 80 ms period.

SIB2 includes information necessary for the terminal to access the cell. This includes information about uplink cell bandwidth, random access parameters, parameters related to uplink power control, and the like.

SIB3 includes cell reselection information. SIB4 includes frequency information of a serving cell and intra frequency information of a neighbor cell related to cell reselection. SIB5 includes information on another E-UTRA frequency and information on inter frequencies of neighboring cells related to cell reselection. SIB6 includes information on UTRA frequency and information on UTRA neighbor cells related to cell reselection. SIB7 includes information on GERAN frequencies related to cell reselection. SIB8 includes information about a neighbor cell.

SIB9 includes an ID of a Home eNodeB (HeNB). SIB10 to SIB12 include public warning messages, for example earthquake warnings. SIB14 is used to support enhanced access barring and controls terminals accessing a cell. SIB15 includes information required for MBMS reception of an adjacent carrier frequency. SIB16 includes GPS time and Coordinated Universal Time (UTC) related information. SIB17 includes RAN assistance information.

Not all SIBs should always exist. For example, SIB9 is not needed in the mode in which the HeNB is constructed by the operator, and SIB13 is not necessary unless the MBMS is provided in the cell.

System information is commonly applied to all terminals connected in a cell, and the terminal must always maintain the latest system information for proper operation. If the system information is changed, the UE should know in advance when the base station transmits the new system information. In order to mutually recognize a radio frame period in which a base station and a terminal can transmit new system information, 3GPP has introduced the concept of a BCCH modification period. It demonstrates concretely below.

6 shows an update of system information.

Referring to FIG. 6, if the base station intends to update the system information in the n + 1th change interval, the base station notifies the terminals of the update of the system information during the nth change interval. The terminal notified of the update of the system information in the nth change interval section receives and applies new system information as soon as the n + 1th change interval starts. If an update of the system information is scheduled, the base station includes the system information modification indicator in the paging message. In general, the paging message is a message received by the idle mode terminal, but because the notification of the update of the system information through the paging message, the connected mode terminal should also receive the paging message from time to time to check whether the system information is updated.

On the other hand, as the amount of data communication increases, there is a continuous discussion for efficiently using radio resources. As part of this effort, on-demand system information (OSI) has been proposed. In the case of on-demand system information, the terminal may request system information from the cell, and the network receiving the request may transmit the requested system information to the terminal.

In addition, research has been conducted on a method of checking whether system information is valid in order to use radio resources efficiently. Specifically, when the serving cell changes as the terminal moves, the existing system information may also be used in the new serving cell. In this case, the terminal may determine whether to use the system information currently held in the new serving cell or request new service information from the network.

Furthermore, even if the serving cell is not changed, when some system information is updated, the terminal should determine whether the system information currently held is valid. In this case, the terminal may update the invalid system information. That is, the terminal may save radio resources by updating only the system information that needs updating without updating all system information.

Hereinafter, a method of determining, by a terminal according to an embodiment of the present invention, whether system information stored in the terminal is valid will be described. According to this embodiment, the terminal may receive and store system information received from the existing serving cell. In addition, as the terminal moves, the serving cell may be changed or existing system information may be updated. In addition, the terminal may receive information (hereinafter, validation information) necessary for validating existing system information from a current serving cell (a new serving cell when the serving cell is changed). In addition, the terminal may determine whether the existing system information is valid in the current serving cell. If the system information is valid in the current serving cell, the terminal may utilize the system information. If the system information is not valid in the current serving cell, the terminal may discard the system information. If the stored system information is no longer valid according to the update of the system information, that is, if the version of the stored system information is not the same as the version required by the validation information, the terminal is a new system as a serving cell. You can request information. Accordingly, the terminal may receive new system information from the serving cell and apply the received system information to perform various operations. Meanwhile, in the present embodiment, system information may be transmitted and stored in the form of an information block, and examples of the information block include SIB1, SIB2, and other System Information Blocks (SIBn).

7 is a flowchart illustrating a method of checking the validity of a system information block according to an embodiment of the present invention.

In step S702, the terminal may receive a system information block from the first cell and store it. The stored system information is common system information, and may be used not only in the serving cell but also in adjacent cells in some cases. The terminal may store at least one of the following information together with the system information block.

-Value tag by system information block (value tag by SIB)

Validity area by system information block (validity area or cell list by SIB)

Version information of the system information block

-Value tag (version index) by version of system information block

-Validity timer configuration information for each system information block (validity timer configuration for each SIB)

The terminal may store a plurality of versions for one system information block. Each of the different versions of the system information block may have different value tags, valid areas, and valid timer settings. In one example, the terminal may store four versions for each system information block. Therefore, while using the first version of the specific system information block, the terminal may retrieve the second version stored without additional reception from the base station when the second version is needed. In the above example, the version information of the system information block may indicate whether the system information block is a first version, a second version, a third version, or a fourth version.

On the other hand, the terminal may store the maximum number of versions of the system information block that can be stored, a new system information block may occur. In this case, the terminal may delete a system information block corresponding to a part of the stored version and allocate version information corresponding to the deleted system information to the new system information block. In other words, when new system information occurs, the terminal may update the version of the corresponding system information block. In the above example, when the first version of the system information block is newly updated, the terminal needs to distinguish whether the system information block corresponding to the first version is the system information block before the update or the system information block after the update. Here, the value tag (version index) for each version indicates the update status of each version of the system information block. That is, by checking the version index of the system information block, the terminal can prevent the system information block before updating even if the version information (for example, the first version) is the same.

For example, the terminal may store a first version, a second version, a third version, and a fourth version for a specific system information block. Here, indices of 1, 3, 5, and 5 may be allocated to the first version, the second version, the third version, and the fourth version, respectively. When the update is performed on the first version, the updated first version may have an index of nine. In this case, the terminal may confirm that the index of the first version is 9, thereby knowing that the corresponding system information block is data after the update. Meanwhile, different indexes (value tags) may be allocated to different versions, but the same indexes may be allocated. In the above example, the index of the third version is 5, the index of the fourth version is 5, and the same as the index itself, but the terminal distinguishes the version information (whether it is the third version or the fourth version) by It may be recognized that the system information block and the fourth version of the system information block are different system information blocks.

The valid area for each system information block indicates an area where the system information block is considered valid, and may include a list of cells in which the system information block is valid.

In relation to the effective timer setting, the terminal may start the timer upon receiving the system information block from the system serving cell. When the terminal receives the new version of the system information block, the timer of the existing system information block corresponding to the system information block may be stopped. If the timer expires, the terminal may consider the system information block as invalid. In addition, the terminal may delete the system information block whose timer has expired.

In step S704, the terminal may change the serving cell to the second cell. According to an embodiment, as the terminal moves, the serving cell of the terminal may be changed to the second cell by handover or cell-reselection procedure. However, as described above, the changing of the serving cell is not an essential step, and even when at least some of the system information blocks are updated, the present embodiment of performing the validity check on the stored system information blocks may be applied. The first cell and the second cell may be classified according to whether the current cell is a serving cell of the terminal. Therefore, when the serving cell is not changed, both the first cell and the second cell may be the same cell as the serving cell of the current terminal.

In operation S706, the terminal may receive validation information necessary for validating the system information block from the second cell. The validity check information may include at least one of the following information.

-Value tag by system information block (value tag by SIB)

Cell ID of the current serving cell

Version information of the system information block

-Value tag (version index) by version of system information block

That is, the validation information may be a value tag of a currently valid system information block, a cell ID of a current serving cell, version information of the system information block, and an index for each version.

In step S708, the terminal may perform a validity check on the stored system information block. In detail, the terminal may determine whether the system information block is valid by comparing the stored system information block with the validity check information. According to an embodiment of the present disclosure, the terminal may include a valid region of a stored system information block, a version of the system information, and a version-specific index, a cell ID of a current serving cell, a version of a system information block included in validation information and the version If the respective indexes match, it may be determined that the corresponding system information block is valid.

Specifically, when the serving cell is changed according to the movement of the terminal, for each system information block, the system ID of the new serving cell is included in a valid area (cell list) of the stored system information block and included in the validation information. If the version of the information block and the version of the stored system information block are the same, and the index for each version is the same, the terminal may determine that the stored system information block is valid. If, as a result of performing a validity check on a system information block, the value tag of the validation information and the value tag of the system information block are not the same, or the valid area of the system information block in which the cell ID of the new serving cell is stored (cell If the index of the system information block and the index of the stored system information block that are not included in the list, or the index of the stored system information block is not the same, or the index for each version is not the same, the terminal is not valid. You can judge. That is, when at least one of the valid region, the version, and the version-specific index of the stored system information block does not match the validation information, the terminal may consider the system information block to be invalid.

Meanwhile, the terminal may determine that the valid information timer is not valid even for the expired system information block.

In operation S710, when it is determined that the stored system information block is valid, the terminal may use the corresponding system information block.

In operation S712, when it is determined that the stored system information block is invalid, the terminal may discard the system information block. Furthermore, the terminal may newly receive the corresponding system information block from the second cell (current serving cell). In one example, the UE may delete the same type of system information block as the received system information block for all valid system information blocks received from the current serving cell. In addition, for all system information blocks that the terminal considers invalid, the terminal may discard the system information block.

In addition, when the UE is included in the valid area list of the system information block in which the cell ID of the serving cell is currently stored, but the value tag included in the validation information is different from the value tag of the stored system information block, the corresponding system information block is determined. Since the terminal is not currently valid in the serving cell, the terminal may discard the corresponding system information block. If the cell ID of the current serving cell is not included in the valid area list of the system information block stored in the terminal, the system information block may not be discarded. This is because when the terminal moves to a cell included in the valid region list, the system information may be regarded as a valid system information block again.

8 is a flowchart illustrating a method of checking the validity of a system information block according to an embodiment of the present invention.

In step S802, the terminal may receive the system information block from the serving cell and store it. In the present embodiment, the system information is common system information, which may be used in adjacent cells in some cases. In addition, the system information may be received and stored in the form of an information block, and examples of the information block include SIB1, SIB2, and other System Information Blocks (SIBn). The terminal may store at least one of the following information together with the system information block.

Validity area by system information block (validity area or cell list by SIB)

Version information of the system information block

-Value tag (version index) by version of system information block

Validity timer configuration

In operation S804, the terminal may receive validation information necessary for validating the system information block from the current serving cell. The validity check information may include at least one of the following information.

Cell ID of the current serving cell

-Version information of system information block

-Value tag (version index) by version of system information block

That is, the validity check information may include at least one of a cell ID of a current serving cell, version information of a system information block considered to be valid, and information on an index indicating the update status of the version. On the other hand, the current serving cell in which the terminal receives the validation information in step S704 may be the same as or different from the existing serving cell in which the terminal receives the system information block in step S702.

In operation S806, the terminal may perform validation of the system information block by comparing the stored validity area for each system information block, the version of the system information block, and the version-specific index with the validation information. Specifically, the terminal includes the cell ID in the cell list of the valid area of the stored system information block, the version of the stored system information block is the same as the version included in the validation information, and the When the version index and the version index included in the validity check information are the same, the terminal may determine that the stored system information block is valid. In addition, the terminal does not include the cell ID in the cell list of the valid region of the stored system information block, the version of the stored system information block and the version included in the validation information, or the stored system information block If the version index of the and the version index included in the validity check information is not the same, the terminal may determine that the stored system information block is invalid. If it is determined that the stored system information block is invalid, the terminal may discard the stored system information block. In addition, the terminal may request transmission of a new system information block for the discarded system information block to the current serving cell.

However, even if it is determined that the system information block is invalid, the value tag of the stored system information block and the value tag included in the validation information are the same, and the cell ID is displayed in the cell list of the valid area of the stored system information block. If is not included, the terminal may retain the stored system information block as it is.

Meanwhile, the terminal may receive valid timer setting information for each system information block from the serving cell, and may determine that the valid timer is not valid for the expired system information block.

The base station 900 includes a processor 901, a memory 902, and a transceiver 903. The memory 902 is connected to the processor 901 and stores various information for driving the processor 901. The transceiver 903 is coupled to the processor 901 to transmit and / or receive wireless signals. Processor 901 implements the proposed functions, processes, and / or methods. In the above-described embodiment, the operation of the base station may be implemented by the processor 901.

The terminal 910 includes a processor 911, a memory 912, and a transceiver 913. The memory 912 is connected to the processor 911 and stores various information for driving the processor 911. The transceiver 913 is connected to the processor 911 to transmit and / or receive a radio signal. Processor 911 implements the proposed functions, processes, and / or methods. In the above-described embodiment, the operation of the terminal may be implemented by the processor 911.

The processor may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage device. The transceiver may include baseband circuitry for processing wireless signals. When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in memory and executed by a processor. The memory may be internal or external to the processor and may be coupled to the processor by various well known means.

Based on the examples described above, various techniques in accordance with the present disclosure have been described with reference to the drawings and reference numerals. For convenience of description, each technique described a number of steps or blocks in a specific order, but the specific order of these steps or blocks does not limit the invention described in the claims, and each step or block may be implemented in a different order, or In other words, it is possible to be performed simultaneously with other steps or blocks. In addition, it will be apparent to those skilled in the art that the steps or blocks have not been described in detail, and that at least one other step may be added or deleted without departing from the scope of the invention.

The above-described embodiments include various examples. Those skilled in the art will appreciate that not all possible combinations of examples of the inventions can be described, and that various combinations can be derived from the description herein. Therefore, the protection scope of the invention should be judged by combining various examples described in the detailed description within the scope of the claims described below.

Claims

In the method of the terminal performs a validation check (validity check) of the system information block (SIB) in a wireless communication system,

Storing the system information block received from the serving cell;

Receiving validation information for validating the stored system information block from a current serving cell; And

Validation of the system information block is performed by comparing a validity area for each stored system information block, version information of the stored system information block, and a version index indicating the update status of each version with the validation information. Comprising the steps of:
The method of claim 1,

The validation information includes information about a cell ID of a current serving cell, a version of a system information block that is considered valid, and the version-specific index.
The method of claim 2,

The performing of the validation check may include the cell ID in a cell list of a valid area of the stored system information block, a version of the stored system information block and a version included in the validation information, and the stored If the version-specific index of the system information block and the version-specific index included in the validation information, the terminal determines that the stored system information block is valid.
The method of claim 1,

The performing of the validation check may include that the cell ID is not included in the cell list of the valid region of the stored system information block, the version of the stored system information block is not the same as the version included in the validation information, or Or if the version index of the stored system information block and the version index included in the validity check information are not the same, the terminal determines that the stored system information block is invalid.
The method of claim 4, wherein

Discarding the stored system information block if it is determined that the stored system information block is invalid.
The method of claim 4, wherein

The performing of the validation may include comparing the value tag of the stored system information block with the value tag included in the validation information.

The system information block is determined to be invalid, but the value tag of the stored system information block and the value tag included in the validation information are the same, and the cell ID is included in the cell list of the valid region of the stored system information block. If not included, the terminal retains the stored system information block as it is.
The method of claim 5, wherein

Requesting transmission of a new system information block for the discarded system information to a current serving cell.
The method of claim 1,

Receiving valid timer setting information for each system information block from the serving cell.
The method of claim 8,

And performing the validity check includes determining that the validity timer is invalid for an expired system information block.
In the terminal for validating the system information block in a wireless communication system,

Memory; Transceiver; And a processor connecting the memory and the transceiver, wherein the processor includes:

Store the system information block received from the serving cell,

Receiving validation information for validating the stored system information block from a current serving cell,

Validity of the stored system information block by comparing a validity area for each stored system information block, version information of the stored system information block, and a version-specific index indicating an update status of each version with the validation information, respectively. And configured to perform a test.
The method of claim 10,

The validation information includes a cell ID of a current serving cell, a version of a system information block that is considered valid, and information about the version-specific index.
The method of claim 11,

The processor may include the cell ID in a cell list of a valid area of the stored system information block, a version of the stored system information block is the same as a version included in the validation information, and a version of the stored system information block. If the per-index and the per-version index included in the validation information is the same, the terminal is configured to determine that the stored system information block is valid.
The method of claim 10,

The processor may not include the cell ID in the cell list of the valid region of the stored system information block, or the version of the stored system information block is not the same as the version included in the validity check information, or the stored system information. If the version-specific index of the block and the version-specific index included in the validation information is not the same, the terminal is configured to determine that the stored system information block is invalid.
The method of claim 13,

And if it is determined that the stored system information block is invalid, the processor is configured to discard the stored system information block.
The method of claim 13,

The processor is configured to perform the validation by comparing a value tag included in the validation check information with a value tag of the stored system information block,

The system information block is determined to be invalid, but the value tag of the stored system information block and the value tag included in the validation information are the same, and the cell ID is included in the cell list of the valid region of the stored system information block. If not included, the processor is configured to retain the stored system information block as it is.