KR20150129293A - method and apparatus for transmitting and receiving system information in mobile communication system - Google Patents

Abstract

Provided are a method of a terminal for receiving system information of a subsidiary base station by the steps of: setting connection to a main base station; and receiving an RCC connection resetting message including the system information of a cell of an SCG controlled by the subsidiary base station connected to a main base station by a non-ideal backhaul, and a method for sharing a frame offset between an MCG, controlled by the main base station, and an SCG, controlled by the subsidiary base station connected to the main base station by the non-ideal backhaul by the steps of: measuring an SFN and an SN of the cell included in the SCG; and sharing the frame offset, determined based on the SFN and the SN, with the main base station and the subsidiary base station.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for transmitting and receiving system information of a mobile communication system,

The present invention relates to a method and apparatus for transmitting and receiving system information in a dual access mobile communication system in which both a primary base station and a secondary base station are connected to a mobile terminal.

In the 3GPP LTE / SAE (3 ^rd generation partnership project long term evolution / system architecture evolution), standardization of small cell enhancement (SCE) technology is underway. Small Cell Enhancement technology is a technique to increase the capacity of a wireless network by closely cooperating a macro cell base station and a small cell base station by densely arranging small cells in a macro cell based cellular network. The purpose of the small cell improvement technology is to accommodate the explosion of traffic by increasing the spectrum efficiency per unit area by densely arranging the small cells of high density, ensuring coverage necessary for mobile communication and efficient mobility management. In order to achieve the above object, the 3GPP RAN (radio access network) has a scenario and requirements for small cell improvement in evolved-UMTS terrestrial radio access (E-UTRA) and evolved-UMTS terrestrial radio access network (E-UTRAN) In December 2012, the RAN meeting approved the physical layer and upper layer study item (SI) for small cell improvement.

In order to improve the small cell of the cellular network considered in 3GPP, three scenarios related to small cell layout, spectrum, traffic, and compatibility with previous specifications were defined and technical issues and solutions for the defined scenarios were discussed. Scenario 1 is a scenario in which macro cells and small cells use the same frequency in a structure in which macro cells and small cells overlap. Scenario 2 is a scenario in which macro cells and small cells use different frequencies in a structure in which macro cells and small cells overlap. Scenario 3 is a scenario in which only small cells arranged in a structure in which macro cells and small cells are not overlapped are used.

Based on the above scenario, 3GPP studied various element technologies to improve the performance of mobile communication networks due to the introduction of miniaturized cells that are closely integrated through study item period. As a result, 12 is a representative element technology for small cell improvement. A dual connection is one in which a UE is served using radio resources provided by two or more different network connection points connected in a non-ideal backhaul.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for transmitting / receiving system information of an auxiliary cell group in an environment where frame synchronization of cells included in the main base station and cells included in the auxiliary base station is not guaranteed.

According to an embodiment of the present invention, a method is provided in which a terminal receives system information of a supplementary base station. The system information receiving method includes a step of establishing a connection with a main base station, a step of transmitting a system information of a cell of a secondary cell group (SCG) controlled by a primary base station and a secondary base station connected with a non- And receiving a radio resource control (RRC) Connection Reconfiguration message from the primary base station.

In the system information receiving method, the RRC connection re-establishment message may be a message transmitted after the main base station has decided to modify the cell included in the SCG.

In the system information receiving method, the RRC connection re-establishment message may be a message transmitted after the auxiliary base station has decided to update the system information.

In the system information receiving method, the RRC connection re-establishment message may include information on a time point at which the system information is applied.

The system information receiving method may further include a step of performing an additional procedure for a cell included in the SCG based on the system information, and a step of transmitting an RRC connection reconfiguration complete message to the main base station .

The step of performing the additional procedure in the system information receiving method may include applying the system information based on the information about when the system information is applied.

According to another embodiment of the present invention, a terminal for receiving system information of an auxiliary base station is provided. The terminal includes at least one processor, a memory, and a wireless communication unit, wherein the at least one processor executes at least one program stored in the memory to establish a connection with the primary base station, Receiving a radio resource control (RRC) reconnection reconfiguration message including system information of a cell of a secondary cell group (SCG) controlled by a solely connected auxiliary base station from a main base station .

The RRC connection reestablishment message may be a message transmitted after the main base station determines a modification request for a cell included in the SCG.

The RRC connection reestablishment message may be a message transmitted after the auxiliary base station has decided to update the system information.

The RRC connection reestablishment message at the UE may include information about a time point at which the system information is applied.

At least one processor in the MS executes at least one program to perform an additional procedure for a cell included in the SCG based on the system information, and a RRC connection reconfiguration complete message to the main base station And then performing the transmitting step.

At least one processor in the terminal may perform the step of applying the system information based on the information about the time when the system information is applied when the step of performing the additional procedure is performed.

According to another embodiment of the present invention, a terminal includes a master cell group (MCG) controlled by a master eNodeB (MeNB), a secondary eNodeB (SeNB) connected with a primary base station and a non- A method of sharing a frame offset between a secondary cell group (SCG) controlled by a first cell group (SCG) is provided. The frame offset sharing method includes the steps of measuring a system frame number (SFN) and a subframe number (SN) of a cell included in the SCG, and determining a frame offset determined based on the SFN and the SN And sharing with the base station or the auxiliary base station.

The method of sharing a frame offset of the UE further includes receiving a master information block (MIB) from a serving base station, wherein the measuring includes measuring SFN and SN based on the MIB .

The sharing in the frame offset sharing method of the terminal may include transmitting the SFN and the SN to the main base station, and receiving the frame offset from the main base station.

The sharing in the frame offset sharing method of the terminal may include calculating a frame offset based on the SFN and the SN, and transmitting the frame offset to the main base station.

The step of measuring the frame offset in the UE includes receiving a radio resource control (RRC) connection reconfiguration message including a measurement indication information element for a frame offset from the main base station can do.

In the frame offset sharing method of the UE, the RRC connection re-establishment message may include a radio resource management (RRM) measurement configuration message.

The frame offset sharing method of the UE includes receiving an RRC connection reset message for adding a cell included in the SCG from the main base station and transmitting a RRC connection reconfiguration complete message to the main base station .

According to another embodiment of the present invention, a master eNodeB (MeNB) includes a master cell group (MCG) controlled by a main base station, a secondary eNodeB connected to the main base station and a non- A method of sharing a frame offset between a secondary cell group (SCG) controlled by a SeNB is provided. The frame offset sharing method of the main base station includes calculating a frame offset and transmitting a frame offset to an auxiliary base station through a SeNB Addition Request message for a cell of the SCG.

The calculating step of the frame offset sharing method of the main base station may include receiving a system frame number (SFN) of the auxiliary base station, and calculating a frame offset based on the SFN.

In the frame offset sharing method of the primary base station, the step of receiving includes requesting an operation and management (OAM) server for an SFN of a serving base station, and receiving an SFN of a serving base station from an OAM server .

The receiving of the frame offset in the main base station includes a step of requesting the SFN of the auxiliary base station to the auxiliary base station through the X2 interface between the main base station and the auxiliary base station and receiving the SFN of the auxiliary base station from the auxiliary base station can do.

And adding the cell included in the SCG based on the frame offset in the frame offset sharing method of the main base station.

The step of performing the frame offset sharing method in the main base station may include receiving a response message for a supplementary request message from a supplementary base station (SeNB Addition Request Acknowledgment), transmitting a radio resource control request to a user equipment (UE) (RRC) connection reconfiguration message from the UE, a RRC connection reconfiguration complete message from the UE, and a SeNB Reconfiguration Complete message to the auxiliary base station .

In the frame offset sharing method of the main base station, the RRC connection re-establishment message may include information on frame offset.

According to an embodiment of the present invention, in a mobile communication network in which the main base station and the auxiliary base station are connected to each other in a non-ideal backhaul, the main base station shares the frame offset of the auxiliary base station with the mobile terminal, .

1 is a block diagram illustrating a dual-connected network in accordance with one embodiment of the present invention.
2A and 2B are block diagrams illustrating a protocol structure of a control plane and a user plane according to an embodiment of the present invention.
3 is a conceptual diagram illustrating a connection scenario of a UE according to an embodiment of the present invention.
4 is a conceptual diagram illustrating an SFN / SN offset estimation method according to an embodiment of the present invention.
5 is a flowchart illustrating a frame offset sharing method using an SeNB addition procedure according to an embodiment of the present invention.
6 is a flowchart illustrating a frame offset sharing method using a measurement report procedure according to an embodiment of the present invention.
7 is a flowchart illustrating a frame offset sharing method based on a procedure between network function nodes according to an embodiment of the present invention.
8 is a flowchart illustrating a method of transmitting system information of an SCG cell according to an embodiment of the present invention.
9 is a flowchart illustrating a method for transmitting changed system information of an SCG cell according to an embodiment of the present invention.
FIG. 10 is a conceptual diagram illustrating a method of transmitting changed system information considering a transmission delay according to an embodiment of the present invention.
11 is a block diagram illustrating a wireless communication system according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, a terminal is referred to as a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station ), A subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT), a user equipment (UE) AMS, HR-MS, SS, PSS, AT, UE, and the like.

Also, a base station (BS) is an advanced base station (ABS), a high reliability base station (HR-BS), a node B, an evolved node B, eNodeB), an access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR) (RS), a relay node (RN) serving as a base station, an advanced relay station (ARS) serving as a base station, a high reliability relay station (HR) A femto BS, a home Node B, a HNB, a pico BS, a metro BS, a micro BS, ), Etc., and may be all or part of an ABS, a Node B, an eNodeB, an AP, a RAS, a BTS, an MMR-BS, an RS, an RN, an ARS, It may include a negative feature.

1 is a block diagram illustrating a dual-connected network in accordance with one embodiment of the present invention.

In FIG. 1, a master eNodeB (MeNB) 200 is a main base station that mainly performs control and services for a user equipment (UE) 100 in a superposed cellular network environment, and a secondary eNodeB , SeNB) 300 is an auxiliary base station that provides auxiliary services. X2 is an interface used for close cooperation between the MeNB 200 and the SeNB 300. Interworking with the core network CN can be performed through the S1-MME interface and the S1-U interface. For the control plane interworking between the E-UTRAN and the CN, the MeNB 200 can perform a protocol procedure with a mobility management entity (MME) through the S1-MME. The MeNB 200 can consider two types of interworking structure according to the structure of the user plane protocol for the user plane interworking between the E-UTRAN and the CN. In the case of the user plane protocol structure 1, the MeNB 200 can transmit / receive data through a dual connection in cooperation with an S-GW (serving gateway). In the case of the user plane protocol structure 2, the MeNB 200 and the SeNB 300 can transmit / receive data through the dual connection in cooperation with the S-GW. At this time, the mobile terminal maintains a Uu interface with the MeNB 200 and the SeNB 300, respectively, and can transmit / receive data through the Uu interface.

2A and 2B are block diagrams illustrating a protocol structure of a control plane and a user plane according to an embodiment of the present invention.

In FIGS. 2A and 2B, a control plane protocol structure and a user plane protocol structure for supporting dual connection based on the network structure shown in FIG. 1 are shown.

First, a control plane protocol structure will be described with reference to FIG. In the control plane protocol structure, a radio resource control (RRC) protocol layer for controlling radio resources is located in the MeNB 200, and an RRC layer is not located in the SeNB 300. That is, the RRC layer of the MeNB 200 is responsible for the radio resource control function for the cells managed by the MeNB 200 and the SeNB 300, and can perform the RRC procedure between the SeNB 300 and the UE 100 .

Next, referring to FIG. 2B, a user plane protocol structure will be described. The user plane protocol structure can be divided into the user plane protocol structure 1 (UP-Alt. 1) and the user plane protocol structure 2 (UP-Alt. 2) according to whether the bearer is divided and the user plane protocol arrangement of the SeNB 300 .

In user plane protocol structure 1, the bearer split function is not supported. The MeNB 200 includes a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, a media access control (MAC) layer, and a physical ) Layer. The SeNB 300 also includes a PDCP layer, an RLC layer, a MAC layer, and a PHY layer. That is, in the user plane protocol structure of the UP-Alt. 1, the SeNB 300 includes all the user plane protocol layers of the eNB presented in 3GPP LTE-A.

User plane protocol structure 2 supports bearer partitioning function. The MeNB 200 includes a PDCP layer, an RLC layer, a MAC layer, and a PHY layer, and the SeNB 300 includes an RLC layer, a MAC layer, and a PHY layer. That is, in the user plane protocol structure of the UP-Alt. 2, the SeNB 300 includes the RLC layer, the MAC layer, and the PHY layer among the user plane protocol layers of the eNB presented in 3GPP LTE-A. At this time, the user plane protocol used for the dual connection additionally includes a function for supporting the dual connection to the functions of the existing 3GPP LTE-A.

 3 is a conceptual diagram illustrating a connection scenario of a UE according to an embodiment of the present invention.

In FIG. 3, the UE 100 may support dual link and carrier aggregation (CA). MeNB 200 controls three cells operating on component carriers (CC) 1, CC2 and CC3, and SeNB 300 controls two cells operating in CC4 and CC5. At this time, three cells operating in CC1, CC2 and CC3 are included in a master cell group (MCG) 210, and two cells operating in CC4 and CC5 are included in a secondary cell group ) ≪ / RTI > Then, the UE can receive a dual connection-based service through three cells (three cells operating in CC1, CC2, and CC3) controlled by the MeNB 200. [

The UE 100 according to an embodiment of the present invention performs a search procedure for a specific cell and receives system information used in the searched cell. The UE 100 can acquire the symbol synchronization and the frame synchronization of the searched cell and obtain the physical cell identifier (PCI) used in the searched cell through the cell search procedure. Then, the UE 100 can additionally perform the cell access procedure by receiving the system information including the bandwidth used in the cell and the uplink / downlink setting information.

In the mobile communication system according to an exemplary embodiment of the present invention, two types of system information may be used depending on a type of channel and information to be transmitted, and each system information may be transmitted to the terminal through an RRC message.

First, a master information block (MIB) is essential for system connection and contains limited information and can be transmitted through a broadcast channel (BCH). The MIB may include downlink cell bandwidth information, physical hybrid automatic repeat request indicator channel (PHICH) setting information, and system frame number (SFN) information.

The system information block (SIB) includes cell-specific information necessary for system connection and can be transmitted through a downlink-shared channel (DL-SCH). Depending on the information included, various SIBs from SIB1 to SIB17 may exist.

In the mobile communication network supporting dual connection according to an embodiment of the present invention, the MeNB 200 and the SeNB 300 are connected through a non-ideal backhaul, and each eNB can perform a CA function. Therefore, the MeNB 200 and the SeNB 300 can provide services to the UE 100 using the plurality of CCs through the CA function as well as the dual connection function, and independent system information can be used for each CC have.

3, in a mobile communication network supporting dual connection according to an exemplary embodiment of the present invention, a group of cells controlled by the MeNB 200 is an MCG 210, and a cell controlled by the SeNB 300 The group is SCG 310. A cell used for transmission of a physical uplink control channel (PUCCH) of a cell group (CG) in the MCG 210 is a primary cell (PCell) The cell used for transmission of the PUCCH of the CG is a special primary cell (pSCell).

In a mobile communication network provided with a dual connection according to an embodiment of the present invention, an environment where synchronization between the MeNB 200 and the SeNB 300 is performed and an environment where synchronization is not performed can be considered. Since the RRC layer of the control plane protocol is located in the MeNB 200, the procedure for transmitting and changing the system information of the MeNB 200 may be performed according to the RRC standard procedure, and the SeNB 300 may transmit the RRC The method of transmitting the system information to the cell controlled by the SeNB 300 will be described below. In the small cell enhancement (SCE) in which the MeNB 200 and the SeNB 300 are connected through the non-ideal backhaul, the application time point of the changed system information in the cell included in the SCG 310 controlled by the SeNB 300 May affect the performance of the system, and changing the system information of the pSCell may affect the uplink setting of all the cells included in the SCG 310, which may greatly affect the performance of the SCG 310.

In the case of a cell (hereinafter referred to as 'MCG cell') included in the MCG 210 controlled by the MeNB 200, PCell and SCell are connected through an ideal backhaul, The system information of the MCG cell 210 can be transmitted.

First, the UE 100 can receive the system information at the connection time to the PCell. At this time, the UE 100 can acquire the system information through the reception of the MIB and the SIB after the cell search procedure. In addition, the UE 100 can receive system information even when the SCell is added. When the SCell is added, the system information of the SCell to be added can be transmitted to the UE 100 through the RRC Connection Reconfiguration message. Thereafter, the UE 100 may add the SCell using the system information included in the received RRC connection re-establishment message.

When the system information of the PCell included in the MCG 210 is changed, the UE 100 periodically receives a paging message to confirm whether the system information has been changed in the PCG of the MCG 210. [ When the system information of the SCell included in the MCG 210 is changed, the MeNB 200 can transmit the changed system information to the UE 100 through the RRC connection re-establishment procedure when the system information is changed. At this time, an information element (IE) included in the RRC connection re-establishment message may include information on Release and Addition of SCell in which the system information is changed.

When the system information of a cell (hereinafter referred to as 'SCG cell') included in the SCG 310 controlled by the SeNB 300 is changed, the changed system information can be transmitted to the UE 100 according to the following method.

- Alt.1: How to use the wireless connection interface (MeNB / UE Uu) between MeNB and UE

In this case, similar to the existing CA, system information of the SCG cell can be transmitted to the UE 100 through the MeNB 200. [ The system information is transmitted through the X2 interface between the SeNB 300 and the MeNB 200 and the MeNB 200 receiving the system information from the SeNB 300 transmits the system information of the SCG cell to the UE 100 through the RRC connection re- Information can be conveyed.

- Alt.2: How to use the wireless connection interface (SeNB / UE Uu) between SeNB and UE

In this case, the UE 100 can directly access the SeNB 300 and receive broadcast system information.

The system information of the SCG cell is transmitted to the UE 100 through the radio access interface between the MeNB 200 and the UE 100 in consideration of the compatibility with the existing standard and the complexity problem in the UE 100. [ ). ≪ / RTI >

In this case, when the system information of the SCG cell is transmitted using the Alt.1 in the state where the MCG cell and the SCG cell are unsynchronized, the system information used in the SCG cell and the system information used in the UE 100 are used Synchronization is required. For example, if the time required to transmit / receive a message on X2 is 60 ms, the system information of the SCG cell may be applied to the UE 100 at least 60 ms after transmission. Therefore, the setup information used for transmission in the UE 100 during the time corresponding to the X2 delay may not match the system information used in the SCG cell. This inconsistency can affect system performance and X2 delay needs to be taken into consideration when transmitting SCG cell system information. The UE 100 according to an embodiment of the present invention can acquire or share a frame offset between the MCG cell and the SCG cell and efficiently receive the system information using the frame offset between the MCG cell and the SCG cell .

A mobile communication system according to an exemplary embodiment of the present invention may define a frame as a system frame and a subframe, and may use a frame defined in an operation procedure of the system. A typical procedure using a system frame number and a subframe number is discontinuous reception (DRX) setting, measurement gap setting, and the like, and frame information (i.e., , A system frame number or a subframe number, etc.) can be used.

The UE 100 providing the dual connection uses the independent user plane protocol for connection to the MeNB 200 or the SeNB 300 so that the MeNB 200 and the SeNB 300 recognize each other's frame information If it works, you can get a benefit from network performance. For example, when the MeNB 200 and the SeNB 300 perform control at the same time through coordination in the DRX setting for reducing the battery consumption of the UE 100, the CG of each eNB is independently Higher performance can be expected when performing the control.

As described above, since the MCG cell and the SCG cell have independent system frame numbers and subframe numbers and are not synchronized, the MeNB 200 and the SeNB 300, which provide the dual connection, It is necessary to grasp the system frame number and the offset information of the subframe number. It is also necessary to share the frame offset between the MCG cell and the SCG cell for the purpose of grasping or applying the point of application of the system information of the SCG cell or for transferring and applying the system information considering the delay of the X2 interface .

In a mobile communication network in which a dual connection is provided in accordance with an embodiment of the present invention, frame offsets (system frame offsets and sur- frame frames offsets) are obtained based on measurements of the UE 100, And can be obtained based on the procedure.

First, a method of obtaining a frame offset based on the measurement of the UE 100 will be described. In the method of acquiring a frame offset based on the measurement of the UE 100, the UE 100 having the dual link function receives the MIB of the SeNB 300 and extracts the SCG cell and the system frame number of the MCG cell from the received MIB frame number, SFN) and a subframe number (SN). At this time, the MIB can be transmitted on a physical broadcast channel (PBCH) of the first subframe of all the system frames. Accordingly, the UE 100 can receive the MIB of the SeNB 300 to acquire the SFN of the SCG cell, and determine the reception time of the MIB as SN0 (subframe number 0) of the SCG cell. Also, the UE 100 can recognize the SFN and the SN of the MCG cell at the time of receiving the MIB of the SCG cell, so that the SFN and the SN of the MCG cell and the SCG cell can be known. Therefore, in one embodiment of the present invention, the UE 100 can know the SFN of the MCG cell through the receiving time point of the MIB (i.e., SN0 of the SCG cell) The position of the system frame of the SCG 310 can be deduced.

Since the MCG cell and the SCG cell operate asynchronously with each other, a plurality of SNs of the SN of the MCG cell may correspond to the SN0 at which the UE 100 receives the MIB of the SCG cell, The SN of the corresponding MCG cell can be a maximum of two.

4 is a conceptual diagram illustrating an SFN / SN offset estimation method according to an embodiment of the present invention.

Referring to FIG. 4, the UE 100 receives the MIB in the SFN n of the SCG cell and can know the SFN and the SN of the MCG cell corresponding to the SN 0 (i.e., sf (subframe) 0) of the SCG cell. In Fig. 4, the SN of the MCG cell corresponding to SN0 of the SCG cell is sf2 and sf3. Then, information on the SFN and SN of the MCG cell and the SCG cell obtained from the UE 100 is transmitted to the MeNB 200 and can be used for deriving the offset. In one embodiment of the present invention, the SFN offset between the MCG cell and the SCG cell can be derived through the difference between the SFN of the MCG cell and the SFN of the SCG cell. The SFN of the SCG cell can be derived from Equation (1) below.

The difference between the SFN of the MCG cell and the SN contained in the SFN of the SCG cell can be known through the SN of the MCG cell corresponding to the time point of receipt of the MIB of the SCG cell (i.e., sf0 of the SCG cell).

Next, a method of measuring the frame offset based on the procedure between network function nodes will be described. The method of measuring the frame offset based on the procedure between the network function nodes can be divided into the method by the operation and management (OAM) server and the method through the X2 interface between the eNBs.

In the method of acquiring the frame offset through the OAM server, the OAM server requests and receives the SFN / SN from another node requested at a specific time (time t) according to the SFN request received from the specific node, To the MeNB 200. To this end, the OAM server may utilize a global positioning system (GPS), IEEE 1588, or network time protocol (NTP). In order to obtain the SFN / SN of the SeNB 300 providing the dual connection, the MeNB 200 requests SFN / SN information corresponding to a specific time (absolute time based) to the OAM server, The OAM server having received the request from the SeNB 300 may transmit the SFN / SN of the received SeNB 300 to the MeNB 200 after performing the Query procedure with respect to the SeNB 300. [ Then, the MeNB 200 can acquire the frame offset of the SeNB 300.

In the method of acquiring the frame offset through the X2 interface between eNBs, the MeNB 200 requests the SeNB 300 from the SeNB 300 at a specific time (time t), and obtains the frame offset of the SFN / SN based on the SFN / have. At this time, the MeNB 200 can use GPS, IEEE1588, NTP, or the like. In order to obtain the SFN / SN of the SeNB 300 providing the double connection, the MeNB 200 requests the SeNB 300 to receive SFN / SN information corresponding to a specific time (absolute time based) When the SeNB 300 transmits the SFN / SN information obtained as a measurement result to the MeNB 200 after performing the measurement procedure, the MeNB 200 calculates the frame offset of the SeNB 300 based on the SFN / SN information .

A signaling method for sharing the frame offset between the MCG cell and the SCG cell will be described below with reference to FIGS. 5 to 7. FIG. The signaling method for frame offset sharing between the MCG cell and the SCG cell may be performed based on the measurement of the UE 100 or may be performed based on a procedure between network function nodes.

First, a signaling method for acquiring and sharing a frame offset based on the measurement of the UE 100 may be divided into a method using a SeNB addition procedure or a method using a SeNB modification procedure and a method using a measurement report procedure. The method of obtaining the frame offset based on the measurement of the UE 100 is to obtain the frame offset between the MCG cell and the SCG cell in which the dual connection is to be established. .

5 is a flowchart illustrating a frame offset sharing method using an SeNB addition procedure according to an embodiment of the present invention.

The MeNB 200 determines whether the MCG cell and the SCG are allocated through measurement of the UE 100 when the SCG cell is added considering the measurement result of the radio resource management (RRM) of the UE 100 and the load of the SCG cell. The frame offset between the cells can be obtained and shared with the UE 100.

First, the MeNB 200 requests the SeNB 300 to add a cell to the SCG (S501). At this time, the MeNB 200 delivers an SCG cell addition request message (SeNB Addition Request) for the dual connection considering the RRM measurement result of the UE 100 and the load status of the SCG cell.

Thereafter, the SeNB 300 transmits a modification request for adding a cell to the SCN to the MeNB 200 (S502). That is, the SeNB 300 performs an admission procedure for the SCG cell addition request and transmits a response message (SeNB Addition Request Acknowledgment) for the SCG addition request for adding the SCG cell to the MeNB 200 have.

Then, the MeNB 200 instructs the UE 100 to measure the frame offset with respect to the cell to be subjected to the SCG Addition (S503). The MeNB 200 can instruct the UE 100 to measure the frame offset through the RRC connection re-establishment message. At this time, the RRC Connection Reconfiguration message may include a measurement indication information element for the frame offset of the SCG cell.

The UE 100 performs measurement on the SCG addition target cell, receives the MIB information of the SCG addition target cell, and measures the SFN / SN information based on the received MIB information (S504). At this time, the UE 100 may measure the SFN / SN information from the MIB information using the method illustrated in FIG. 4 and Equation (1).

The UE 100 calculates the frame offset of the MCG cell and the SCG cell using the SFN / SN information of the measured MCG cell and the SCG cell (S505). Then, the UE 100 may report the calculated frame offset to the MeNB 200 through an RRC Connection Reconfiguration Complete message (S506). At this time, the RRC connection reset completion message may include an information element for the SCG cell frame offset.

In this case, or in another embodiment of the present invention, the UE 100 reports the SFN / SN information of the measured MCG cell and the SCG cell to the MeNB 200 and the SFN of the MCG cell and the SCG cell reported by the MeNB 200 / SN information can be used to calculate the frame offset of the MCG cell and the SCG cell.

Finally, the MeNB 200 transmits frame offset information to the SeNB 300 through SeNB Reconfiguration Complete (S507). At this time, the SeNB Reconfiguration Complete message may include a frame offset information element.

6 is a flowchart illustrating a frame offset sharing method using a measurement report procedure according to an embodiment of the present invention.

The MeNB 200 may obtain the frame offset between the MCG cell and the SCG cell and share it with the UE 100 through the RRM measurement report of the UE 100. [ Referring to FIG. 6, the MeNB 200 acquires the SFN of the SCG cell using the measurement report through the measurement configuration that instructs the UE 100 supporting the dual link function to acquire the SFN of the cell And share the acquired SFN information with the UE 100. [

First, the MeNB 200 transmits an RRM measurement configuration message for SFN / SN measurement of the SCG cell to the UE 100 (S601). At this time, the RRM measurement setup message may be included in the RRC connection reset message, and the RRC connection reset message may include the measurement indication information element for the frame offset of the SCG cell. Then, the MeNB 200 acquires the cell ID (ECGI), which is the PCI of the cell, in addition to the previously measured and reported evolved cell global identifier (ECGI) Message. ≪ / RTI >

Thereafter, the UE 100 transmits a response to the measurement setup message to the MeNB 200 through the RRC connection re-establishment completion message (S602). Then, the UE 100 measures the SCG cell addition target cell, receives the MIB information of the SCG cell, and measures the SFN / SN information through the received MIB (S603). Then, the UE 100 calculates the frame offset between the MCG cell and the SCG cell using the measured SFN / SN information (S604). Then, the UE 100 transmits a measurement report including information on the calculated frame offset to the MeNB 200 (S605). At this time, the measurement report message may include an information element for the frame offset of the SCG cell.

If the MeNB 200 is responsible for calculating the frame offset, the UE 100 reports the measured SFN / SN information to the MeNB 200, and the MeNB 200 transmits the SFN / The offset can be calculated.

When the UE 100 is instructed to acquire a cell identifier (ECGI) for PCI, the UE 100 may receive the system information and acquire the ECGI, and then report the obtained ECGI to the MeNB 200.

Thereafter, the calculated frame offset information may be transmitted from the MeNB 200 to the SeNB 300 through an SeNB Addition Request message (S606). At this time, the SeNB addition request message may include a frame offset information element. The SeNB 300 transmits an SCG Add Request Acknowledgment to the MeNB 200. The SeNB 300 transmits a SeNB Addition Request Acknowledgment to the MeNB 200, Sending an RRC connection reset message to the UE 100 after the UE 100 has applied system information about the cell of the SCG, and transmitting an RRC connection reset completion message to the MeNB 200, May transmit a SeNB Reconfiguration Complete message to the SeNB 300 (S607).

Next, a description will be given of how the frame offset is acquired and shared based on the procedure between network function nodes.

7 is a flowchart illustrating a frame offset sharing method based on a procedure between network function nodes according to an embodiment of the present invention.

For obtaining the frame offset shown in Fig. 7, an OAM server may be used or an X2 interface between MeNB 200 and SeNB 300 may be used.

First, a method of obtaining a frame offset between an MCG cell and an SCG cell at a specific point in time using an OAM server will be described (S701). The MeNB 200 requests the SFN of the specific SeNB 300 corresponding to the specific time point to the OAM server. The OAM server receiving the request of the MeNB 200 requests the specific SeNB 300 for the SFN value for the specific time (absolute time). At this time, the specific SeNB 300 can measure the SFN value at a specific time using GPS, IEEE1588, or NTP. Thereafter, the OAM server transfers the received SFN to the MeNB 200, and the MeNB 200 can calculate the frame offset of the SFN based on the SFN received from the OAM server.

Next, a method of obtaining the frame offset between the MCG cell and the SCG cell at a specific point in time using the X2 interface will be described (S701 '). First, the MeNB 200 requests the SeNB 300 for the SFN at a specific point in time. The SeNB 300 that has received the request measures the SFN for a specific time (absolute time) using GPS, IEEE 1588, or NTP, and transfers the measured SFN to the MeNB 200. The MeNB 200 can calculate the frame offset of the SFN based on the received SFN.

Thereafter, the MeNB 200 transmits the calculated frame offset to the SeNB 300 through an SCN addition request message (S702). At this time, the SCG addition message may include a frame offset information element. Thereafter, an additional procedure of the SCG cell may be started based on the shared frame offset, which is performed by the SeNB 300 transmitting a SeNB Addition Request Acknowledgment to the MeNB 200, Sending an RRC connection reset message to the UE 100 after the UE 100 has applied the system information about the cell of the SCG and sending an RRC connection reset complete message to the MeNB 200, May transmit a SeNB Reconfiguration Complete message to the SeNB 300 (S703). At this time, the information about the frame offset may be shared with the UE 100 through the RRC connection re-establishment message.

Hereinafter, a system information transfer method of the SCG cell will be described, and a system information transfer method for connection to a specific SCG cell and a system information change method for additional connection to a specific SCG cell will be described below.

8 is a flowchart illustrating a method of transmitting system information of an SCG cell according to an embodiment of the present invention.

According to one embodiment of the present invention, when a Scell is added to a specific SeNB 300 for a dual connection, a procedure for changing the SCG cell can be performed. At this time, the cell connected to the SeNB 300 is pSCell or SCell, and the UE 100 transmits a UE-specific dedicated RRC signaling procedure to the UE 100 in order to receive the system information of the cell Can be performed. That is, system information of the pSCell or sSCell to be added can be transmitted to the UE 100 via the SeNB 300 and the MeNB 200.

First, the MeNB 200 transmits a SeNB Modification Request message for changing the SCG cell to the SeNB 300 (S801). The SeNB 300 receiving the SeNB change request message from the MeNB 200 transmits the system information as a container type information element to the MeNB 200 through a SeNB Modification Request Acknowledgment message (S802). That is, in the system information transferring method according to an embodiment of the present invention shown in FIG. 8, the system information transfer of the SCG cell can be triggered by the MeNB 200.

Then, the MeNB 200 inserts an information element (including the system information of the SCG cell) for adding the SCG cell to the RRC connection re-establishment message and transmits the information element to the UE 100 (S803). The UE 100 may perform the SCG cell addition procedure based on the system information of the SCG cell included in the RRC connection re-establishment message (S804). After the SCG cell is added, the UE 100 transmits an RRC connection reset completion message to the MeNB 200 in step S805. Upon receiving the RRC connection re-establishment completion message, the MeNB 200 transmits SeNB reconstruction to the SeNB 300 Message (SeNB Reconfiguration Complete) (S806). The method shown in Fig. 5 may be used for transmitting system information when the SCG cell is connected according to another embodiment of the present invention.

FIG. 9 is a flowchart illustrating a method of transmitting system information of an SCG cell according to another embodiment of the present invention. FIG. 10 is a conceptual diagram illustrating a method of transmitting changed system information considering a transmission delay according to an embodiment of the present invention. to be.

The method of transmitting the system information of the SCG cell according to another embodiment of the present invention can be applied when the system information used in the SCG cell is changed when the UE 100 is connected to the SCG cell.

If the changed system information is transmitted without considering the use time of the system information between the SCG cell and the UE 100, the system performance may be degraded. Therefore, the use timing of the system information needs to be synchronized between the SCG cell and the UE 100 .

Therefore, the SeNB 300 transfers the changed system information to the MeNB 200 in consideration of the time when the system information of the SCG cell is changed and the transmission delay on the X2. 10, the transmission delay when the (backhaul delay and MeNB / UE radio transmission including delay between) the ΔT _L, SeNB (300) is of ΔT _L old from the time point at which the system information 1000 is changed, and any time By sending a system information update message to the MeNB 200, the SeNB change procedure for system information change can be started.

The changed system information can also be transmitted through the dedicated RRC signaling procedure specific to the UE 100 and the changed system information is transmitted to the UE 100 via the SeNB 300 and the MeNB 200. [

First, the SeNB 300 determines the update of the system information (S901). The SeNB 300 transmits the changed system information and the SFN / SN information about the time when the changed system information is applied to the SeNB 300 through the SeNB modification request message (SeNB Modification Request) 200 (S902). In other words, in the system information transferring method according to another embodiment of the present invention shown in FIG. 9, system information transfer of the SCG cell can be triggered by the SeNB 300.

In step S903, the MeNB 200 transmits information on the changed system information and the changed system information to the UE 100 through the RRC connection re-establishment message. At this time, the RRC Connection Reconfiguration message transmitted by the MeNB 200 may include an information element for release and addition of the SCell whose system information has been changed. In addition, the information on the time point at which the changed system information is applied may be information on the SFN / SN.

Upon receiving the RRC connection re-establishment message, the UE 100 recognizes the application time point at which the changed system information is applied through the received SFN / SN information element, and determines, based on the application point, The system information update operation can be performed using the information (S904). The UE 100 that has completed the system information update transmits an RRC Connection Reconfiguration Complete message to the MeNB 200 in step S905 and the MeNB 200 receiving the RRC connection re-establishment completion message transmits the SeNB (SeNB Modification Confirmation) message to the base station 300 (S906).

11 is a block diagram illustrating a wireless communication system according to another embodiment of the present invention.

11, a wireless communication system according to an embodiment of the present invention includes a base station 1110 such as a MeNB 200 or a SeNB 300 and a terminal 1120 such as a UE 100. [

The base station 1110 includes a processor 1111, a memory 1112, and a radio frequency unit (RF unit) 1113. The memory 1112 may be connected to the processor 1111 to store various information for driving the processor 1111. [ The wireless communication unit 1113 is connected to the processor 1111 to transmit and receive a wireless signal. The processor 1111 may implement the functions, processes, or methods suggested by embodiments of the present invention. In this case, the wireless interface protocol layer in the wireless communication system according to an embodiment of the present invention can be implemented by the processor 1111. [ The operation of the base station 1110 according to an embodiment of the present invention may be implemented by the processor 1111. [

The terminal 1120 includes a processor 1121, a memory 1122, and a wireless communication unit 1123. The memory 1122 may be coupled to the processor 1121 to store various information for driving the process 1121. The wireless communication unit 1123 is connected to the processor 1121 to transmit and receive a wireless signal. The processor 1121 may implement the functions, steps, or methods suggested by embodiments of the present invention. In this case, in the wireless communication system according to an embodiment of the present invention, the wireless interface protocol layer can be implemented by the processor 1121. The operation of the terminal 1120 according to an embodiment of the present invention may be implemented by the processor 1121. [

In an embodiment of the present invention, the memory may be located inside or outside the processor, and the memory may be connected to the processor via various means already known. The memory may be any type of volatile or nonvolatile storage medium, e.g., the memory may include read-only memory (ROM) or random access memory (RAM).

According to the embodiment of the present invention as described above, in the mobile communication network in which the main base station and the auxiliary base station are connected by a non-ideal backhaul, the main base station shares the frame offset of the auxiliary base station with the mobile terminal, Lt; / RTI >

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (26)

A method for a terminal to receive system information of an auxiliary base station,
Establishing a connection with the primary base station, and
A radio resource control (RRC) connection reconfiguration message including system information of a cell of a secondary cell group (SCG) controlled by the primary base station and an auxiliary base station connected with a non-ideal backhaul message From the main base station
And receiving the system information. The method of claim 1,
The RRC connection re-
Wherein the message is a message transmitted after the main base station determines modification to a cell included in the SCG. The method of claim 1,
The RRC connection re-
Wherein the system information is a message transmitted after the auxiliary base station determines to update the system information. The method of claim 1,
Wherein the RRC connection re-establishment message includes information on a time point at which the system information is applied. 5. The method of claim 4,
Performing an addition procedure on a cell included in the SCG based on the system information, and
RRC connection reconfiguration complete message to the primary base station
Further comprising the steps of: The method of claim 5,
Wherein performing the additional procedure comprises:
Applying the system information based on information about a time point at which the system information is applied
And receiving the system information. A terminal for receiving system information of an auxiliary base station,
At least one processor,
Memory, and
Wireless communication section
Lt; / RTI >
The at least one processor executing at least one program stored in the memory,
Establishing a connection with the primary base station, and
A radio resource control (RRC) connection reconfiguration message including system information of a cell of a secondary cell group (SCG) controlled by the primary base station and an auxiliary base station connected with a non-ideal backhaul message From the main base station
. 8. The method of claim 7,
The RRC connection re-
Wherein the main base station is a message transmitted after determining a modification request for a cell included in the SCG. 8. The method of claim 7,
The RRC connection re-
Wherein the auxiliary base station is a message transmitted after the auxiliary base station determines to update the system information. 8. The method of claim 7,
Wherein the RRC connection re-establishment message includes information on a time point at which the system information is applied. 11. The method of claim 10,
The at least one processor executing the at least one program,
Performing an addition procedure on a cell included in the SCG based on the system information, and
RRC connection reconfiguration complete message to the primary base station
. 12. The method of claim 11,
Wherein the at least one processor, when performing the step of performing the additional procedure,
Applying the system information based on information about a time point at which the system information is applied
. A terminal is divided into a master cell group (MCG) controlled by a master eNodeB (MeNB), an auxiliary cell group controlled by a secondary eNodeB (SeNB) connected with the primary base station and a non- A method for sharing frame offset between a secondary cell group (SCG)
Measuring a system frame number (SFN) and a subframe number (SN) of a cell included in the SCG, and
Sharing the frame offset determined based on the SFN and the SN with the primary base station or the auxiliary base station
/ RTI > The method of claim 13,
Receiving a master information block (MIB) from the auxiliary base station
Further comprising:
Wherein the measuring step comprises:
Measuring the SFN and the SN based on the MIB
/ RTI > The method of claim 13,
Wherein the sharing comprises:
Transmitting the SFN and the SN to the primary base station, and
Receiving the frame offset from the primary base station
/ RTI > The method of claim 13,
Wherein the sharing comprises:
Calculating the frame offset based on the SFN and the SN, and
Transmitting the frame offset to the primary base station
/ RTI > The method of claim 13,
Wherein the measuring step comprises:
Receiving a radio resource control (RRC) reconnection reconfiguration message including a measurement indication information element for the frame offset from the main base station
/ RTI > The method of claim 17,
The RRC connection re-
A frame offset sharing method comprising a radio resource management (RRM) measurement configuration message. The method of claim 18,
Receiving an RRC connection reestablishment message for addition of cells included in the SCG from the primary base station, and
A step of transmitting an RRC connection reconfiguration complete message to the main base station
Wherein the frame offset sharing method further comprises: A master eNodeB (MeNB) is controlled by a master cell group (MCG) controlled by the main base station and a secondary eNodeB (SeNB) controlled by the non-ideal backhaul CLAIMS What is claimed is: 1. A method of sharing a frame offset between a secondary cell group (SCG)
Calculating the frame offset, and
Transmitting the frame offset to the auxiliary base station through a SeNB Addition Request message for the cell of the SCG;
/ RTI > 20. The method of claim 20,
Wherein the calculating step comprises:
Receiving a system frame number (SFN) of the auxiliary base station, and
Calculating the frame offset based on the SFN
/ RTI > 22. The method of claim 21,
Wherein the receiving comprises:
Requesting an operation and management (OAM) server for the SFN of the serving base station, and
Receiving an SFN of the auxiliary base station from the OAM server
/ RTI > 22. The method of claim 21,
Wherein the receiving comprises:
Requesting the SFN of the auxiliary base station to the auxiliary base station through the X2 interface between the main base station and the auxiliary base station;
Receiving an SFN of the auxiliary base station from the auxiliary base station
/ RTI > 20. The method of claim 20,
Performing addition of cells included in the SCG based on the frame offset
Wherein the frame offset sharing method further comprises: 25. The method of claim 24,
Wherein the performing comprises:
Receiving a response message (SeNB Addition Request Acknowledgment) for the add request message from the auxiliary base station,
Transmitting a radio resource control (RRC) connection reconfiguration message to a user equipment (UE)
Receiving an RRC Connection Reconfiguration Complete message from the UE, and
Transmitting a SeNB reconfiguration complete message to the auxiliary base station
/ RTI > 26. The method of claim 25,
Wherein the RRC connection re-establishment message comprises information about the frame offset.

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