KR20140121672A - Apparatus and Method for Cell Update during Small Data Transmission - Google Patents

Abstract

The present invention relates to an apparatus and a method for cell update during small data transmission. More particularly, the present invention relates to an apparatus and a method for cell update during small data transmission to reduce a signaling load. Also, the present invention relates to a method of updating changed cell information in a network node. In an apparatus and a method for cell update during small data transmission, a terminal which performs small data transmission updates changed cell information in a network when a cell in a cam-on status is changed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cell update method and apparatus,

A transmission method for reducing the signaling load due to a small amount of data transmission in a mobile communication network has been proposed. In the present invention, when the position of a cell is changed during a small amount of data transmission process, a small amount of data transmission must be resumed through a paging process. In this case, a signaling overhead occurs. The present invention relates to a method for updating changed cell information in a related network node when a location of a cell on which a terminal is camped is changed during a small amount of data transmission process.

The present invention There is provided a cell update method and apparatus for a small amount of data transmission in which a terminal updates changed cell information to a network when a cell on which the terminal camp-on is changed in the middle of performing a small amount of data transmission.

1 is a structure diagram of a 3GPP communication network for MTC communication.
2 is a diagram illustrating a method of transmitting a small amount of data using a control plane.
3 is a diagram illustrating a small data fast path procedure for a small amount of data transmission.
FIG. 4 is a diagram illustrating a small data fast path procedure for downlink small amount data transmission.
5 is a diagram illustrating a method of updating a cell when transmitting a small amount of data using a control plane.
FIG. 6 is a diagram illustrating a cell update method of Small data fast path / Connectionless data transmission.
7 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.
8 is a block diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

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

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

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

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

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

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

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

In a system such as LTE and LTE-A, the uplink and downlink are configured based on one carrier or carrier pair to form a standard. The uplink and downlink transmit control information through a control channel such as a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel (PHICH), a Physical Uplink Control CHannel And a data channel such as a Physical Downlink Shared CHannel (PDSCH), a Physical Uplink Shared CHannel (PUSCH), and the like.

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

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

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

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

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

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

At this time, as described below with reference to the drawings, the first UE1 transmits the uplink signal to the eNB and the second UE transmits the uplink signal to the RRH.

Machine type communication (MTC) is a form of data communication that represents machine to machine communication where one or more entities do not necessarily require human interaction.

The 3GPP architecture for MTC is shown in FIG.

End-to-end communication between an MTC application in a mobile communication terminal (UE) and an MTC application in an application server (AS) of an external network of a mobile communication network is performed by a 3GPP system and a service capability server (SCS) Server). The Direct Model in the figure shows a model in which the AS directly connects to the operator network without using SCS to perform user plane communication with the UE.

The Indirect Model represents a model in which the AS indirectly connects to the operator's network through the services of the SCS to perform indirect user-plane communications with the UE or to use additional services such as device triggering.

The Hybrid Model shows the use of direct and indirect models between AS and UE simultaneously.

1 is a structure diagram of a 3GPP communication network for MTC communication.

Configuration List

   UE (User Equipment): A mobile communication terminal, a UE may host one or more MTC applications or generic applications,

   - RAN (Radio Access Network): A radio access network

   - MSC (Mobile Switching Center): Circuit switching based mobile switching center

   - Serving GPRS Support Node (SGSN): A packet-based mobile switching center performing mobility management

   - Gateway GPRS Support Node (GGSN): An entity providing interworking between the GPRS network and an external packet-switched network

   - MME (Mobility Management Entity): An object on the control plane for supporting the mobility management function within the Evolved Packet System (EPS)

   - S-GW (Serving Gateway): Gateway that terminates the interface to E-UTRAN

   - P-GW (PDN Gateway): Gateway that terminates the interface to PDN

   SCS (Service Capability Server): An entity connected to a 3GPP network to communicate with a mobile communication terminal (UEs used for MTC) or a general mobile communication terminal (UE) used for MTC, land mobile network MTC IWF. SCS can be used by one or more MTC applications

  - AS (Application Server): An application in a mobile communication terminal used for MTC through a mobile communication network or a server communicating with an application in a general mobile communication terminal

  - SMS-SC (Short Message Service-Service Center): An entity that performs a function of relaying, storing, and delivering a short message between objects (UE)

  - Home Subscriber Server (HSS): A master database for users. An object that contains the subscription-related information needed to support session processing in the network object.

  - MTC-IWF (InterWorking Function): An object that performs relaying or translating of a signaling protocol used to activate a specific function in the mobile communication network through the Tsp with the SCS server.

  - Tsp: Reference point for control plane signaling between SCS and MTC IWF

  - T4: Reference point between SMS-SC and MTC IWF in home mobile communication network (HPLMN)

  - T5a: The reference point between the MTC-IWF and the serving SGSN.

  - T5b: reference point between MTC-IWF and serving MME

  - T5c: reference point between MTC-IWF and serving MSC

- S6m: Reference point between MTC-IWF and HSS / HLR

In the case of a smartphone using various types of terminals and a variety of applications, a small amount of small data such as a keep-alive signal and a heart beat may be transmitted over a long period of time. A small amount of data transmission method has been proposed as follows.

First, a small amount of data transmission method using a control plane will be described.

2 is a diagram illustrating a method of transmitting a small amount of data using a control plane.

2 is a diagram illustrating a message procedure for a small amount of data transmission in a control plane. When a UE triggered service request procedure or a network triggered service request procedure is used to occasionally generate and transmit a small amount of data with a small data size, It is wasteful and may cause network overload. Therefore, the procedure of FIG. 2 can be used in cases where an IP packet or data with a small amount of data is transmitted occasionally. The procedure of FIG. 2 is briefly described below.

1) Information on whether or not the UE supports the capability to support the 'infrequent small data' procedure for the small-data (small-data) procedure of the UE through an Attach or Tracking Area Update procedure, MME exchanges. The MME can receive information such as configuration details and trends of the terminal from the HSS.

2) If the terminal application decides to transmit a small amount of data using the corresponding procedure, it transmits S-TMSI and small data indicator to the RRC Connection Request message. The eNB then sends an RRC connection setup message to the terminal for wireless connection setup.

3) The terminal sends an RRC Connection Complete message. This includes the NAS PDU containing the IP packet to be transmitted, the EPS bearer ID as an encrypted information element (encrypted IE), and the KSI, sequence number.

4) The eNB forwards the encrypted IP packet to the MME through the S1AP Initial UE message.

5) The MME decodes the IP packet and transmits it to the S-GW, and the S-GW to the P-GW.

6) The MME uses the subscriber information to a. Initiate a generic Service Request procedure to deliver additional data, b. Abort the RRC connection immediately, c. Decide whether to wait for a timeout value to determine if there is a downward small amount of data.

7) If there is a downward small amount of data, the S-GW includes the data (IP packet) to be transmitted in the Downlink Data Notification message and delivers it to the MME.

8) If the MME still maintains the RRC connection, encrypts the small amount of data to be transmitted by combining the EPS Bearer ID and transmits the NAS PDU to the terminal. The MME can be included in the RRC connection release message and delivered to the terminal. When the UE receives the RRC connection release message, it releases the RRC connection.

9) The MME sends a Downlink Data Notification ack message to the S-GW.

If the S-GW receives downlink data corresponding to a small amount of data transmission from the P-GW in the case of downlink small data transmission, it sends a Downlink Data Notification message to the MME together with a small amount of data. The MME performs the paging procedure by attaching the small data flag and performs the procedure from the above step 1 for sending the small amount of data of the UE. In step # 1, the upstream IP packet can not be sent or can be sent including the Dummy IP packet.

The following describes a method of transmitting a small amount of data without generating much signaling using the user plane without using the control plane. There are two methods of this method: Small data fast path and Connectionless data transmission.

First, the small data fast path method is explained.

3 is a diagram illustrating a small data fast path procedure for a small amount of data transmission.

In this method, when a small amount of data is transmitted, Bearer Resource ID, which can identify the S-GW as a destination, is transmitted to the base station, so that the eNB can download a separate UE context from another network node, And derives a Fully Qualified Tunnel Endpoint Identifier (F-TEID) and delivers it to the corresponding S-GW. Security is set up between the terminal and the S-GW without AS-Security setup. Bearer Resource ID and time out value are required for small data fast path beforehand through the Session Management procedure. The detailed procedure is as follows.

1) Encrypt an IP packet that meets a small amount of data condition and transmit it to the eNB together with the Bearer Resource ID.

2) eNB derives SGW S1-U F-TEID through Bearer Resource ID and allocates eNB S1-U F-TEID and transmits it to S-GW together with data.

3) Save the eNB S1-U F-TEUD to transmit when there is a small amount of downlink data, and decrypt and transmit the encrypted data to the P-GW.

4) P-GW transmits data to S-GW when there is a downward small amount of data in P-GW before preset time out value expires.

5) The S-GW transmits the downward small amount of data to the eNB that the UE has camped on using the eNB S1-U F-TEUD which encrypts and stores the downward small amount of data.

6) The eNB forwards the small amount of data to the terminal and the terminal decrypts the encrypted small amount of data.

If the P-GW does not send downlink data in the above step 4, the subsequent operation is not executed. If the time out value set in the terminal, the eNB, and the S-GW expires, the allocated radio resources, Release. If there is a downward small amount of data after the expiration of the time out value, or if there is no location information of a terminal valid in the S-GW, the S-GW transmits a downlink data notification message to the MME to perform paging. At this time, the Paging message transmitted to the UE includes a DL small data flag. After receiving the Paging message, the UE performs Bearer Resource ID to the S-GW from Step 1 above, notifies which eNB the UE is camping on, and sets the security. When transmitting UL small data in response to a paging message, it may send a UL IP packet instead of a Dummy IP packet or send nothing. Figure 4 is a small data fast path procedure for downlink small amount data transmission.

FIG. 4 is a diagram illustrating a small data fast path procedure for downlink small amount data transmission.

The connectionless data transmission method will be described.

Connectionless data transmission is a method of transmitting a small amount of data without establishing a PDN connection using a connection ID. The Connection ID is set in advance between the UE and the S-GW through a Session Management Procedure or a Mobility Management Procedure. When the UE transmits a Connection ID to the eNB when transmitting a small amount of data, the eNB can derive the UL TEID and the IP address of the S-GW. The eNB transmits the DL TEID of the eNB to the S-GW to receive a small amount of data. When the S-GW receives the uplink data, the connectionless data transmission becomes active and the active state is maintained for a preset timer value. If there is downlink data to be transmitted, the DL TEID sent from the eNB is sent together with the downlink small amount data to the eNB that the UE is camping on.

In the case of downlink small amount data transmission, if the connectionless data transmission is not active, the S-GW transmits the MME Downlink Data Notification Message to the MME, and the MME performs the paging including the DL small data transmission cause. When the UE receives the paging, it transmits the Connection ID to the eNB that is currently camping on, as in the uplink small amount data transmission. At this time, the uplink IP packet is not sent or is transmitted including the dummy IP packet.

The above three small data transmission methods can omit the signaling procedure and the bearer setting as compared with the existing service request procedure, and thus can efficiently utilize radio resources and network resources.

In the case of a small amount of data transmission method described above, when a cell on which a UE is camping is changed during a small amount of data transmission process, the process of transmitting a small amount of data must be performed again from the beginning through paging. In this case, a plurality of paging operations are performed in order to complete transmission of a small amount of data, which causes a signaling overhead in the network, which increases the load on the entire network.

In the case where the cell camped on by the terminal is changed in the middle of performing the small amount of data transmission, the terminal updates the changed cell information to the network, thereby reducing the signaling overhead caused by performing the paging several times. .

The present invention is based on the 3GPP network structure.

A method of performing cell update when transmitting a small amount of data using a control plane will be described.

5 is a diagram illustrating a method of updating a cell when transmitting a small amount of data using a control plane.

FIG. 5 shows a procedure of updating a cell when transmitting a small amount of data using a control plane. When the UE moves from the eNB 1 to the eNB 2, it performs cell reselection. After receiving the Paging message including the DL small data flag (or DL small data cause) informing the UE of the downlink data transmission, the UE moves from the eNB 1 to the eNB 2 before performing the cell reselection The cell update is performed. Also, even if the UE moves to another cell before completing the uplink or downlink small amount data transmission according to the network configuration and before receiving the RRC connection release message from the network, the cell update can be performed.

To update the cell, follow the steps below.

Solution 1) Using RRC Connection Reestablishment Request message

When the UE completes the transmission from the eNB 1 to the RRCConnectionComplete message and performs cell reselection, the UE can perform the cell update by transmitting an RRCConnectionReestablishmentRequest message to the eNB 2. At this time, the Reestablishment cause of the RRCConnectionReestablishmentRequest message is set as a small data transmission failure, and the S-TMSI is transmitted to the Reestabue-Identity IE. eNB2 transmits path information such as S-TMSI and DL TEID to the MME to inform that the UE has moved to another cell. The MME first encrypts the downlink small amount data using the KSI, sequence number received from the eNB 1, updates the path information of the corresponding terminal using the S-TMSI and the DL-TEID received from the eNB 2, Can be transmitted.

 An example of the RRCConnectionReestablishement message for performing cell update is as follows.

Solution 2) Using RRC Connection Request Procedure

If cell reselection is performed before the downlink small amount data transmission is completed after the UE receives the Paging message for downlink data transmission, the UE can perform the cell update by transmitting the RRCConnectionRequset message to the eNB2. In this case, the EstablishmentCause shall be mt-Signaling or smalldatatransmission and the initial UE-Identity shall be S-TMSI. The eNB 2 then sends an RRC connection setup message to the terminal for wireless connection setup. The MS sends an RRC Connection complete message. This includes the encoded IE bearer ID, encrypted IE, KSI, and sequence number. eNB2 sends S-TMSI, EPS bearer ID, KSI, sequence number to MME. The MME can recognize that the UE has moved to the eNB 2, encrypt the downlink small amount data using the received KSI, sequence number, update the path information of the UE using the S-TMSI and the DL-TEID received from the eNB 2 And transmit downward small amount of data to eNB2.

The following describes how to update the cell for small data fast path and connectionless data transmission.

Similar to the small data transmission method using the control plane, the UE performs cell reselection when it moves to another cell. After receiving the Paging message including the DL small data flag (or DL small data cause) informing the UE of the downlink data transmission, the UE moves from the eNB 1 to the eNB 2 before performing the cell reselection The cell is updated. In addition, according to the network configuration, cell update can be performed even when the UE completes the uplink or downlink small amount data transmission and the UE moves to another cell before the preset timeout value expires from the network.

FIG. 6 is a diagram illustrating a cell update method of Small data fast path / Connectionless data transmission.

To update the cell, follow the steps below.

Solution 1) Using RRC Connection Reestablishment Request message

After the UE performs cell reselection, it transmits an RRCConnectionReestablishmentRequest message to the eNB2. At this time, the Reestablishment cause of the RRCConnectionReestablishmentRequest message is set as a small data transmission failure, and the S-TMSI is transmitted to the Reestabue-Identity IE. The embodiment of the RRCConnectionReestablishement message for performing the cell update may be the same as the case of the cell update in the small amount of data transmission using the control plane described above.

The eNB 2 transmits the S-TMSI, the C-RNTI, the Physical cell ID of the eNB 2, and the path information to the eNB 1. The eNB 1 requests the S-GW to update the cell of the UE using the information received from the eNB 2. In this case, the path information can be S1-U TEID for small data fast path and DL TEID for connectionless small data transmission. The eNB 1 confirms the terminal information using the S-TMSI and C-RNTI, and transmits the cell update information to the S-GW using the GTP-U message. Based on the received information, the S-GW confirms that the cell of the terminal has been changed and transmits the downward small amount of data to the changed path.

Solution 2) Using RRC Connection Request Procedure

After the UE performs Cell reselection, it sends a RRCConnectionRequset message to eNB2. At this time, you can know the small amount of data transmission by making Establishmentcause as mt-Signaling or smalldatatransmission. And initialUE-Identity is S-TMSI. The eNB 2 then sends an RRC connection setup message to the terminal for wireless connection setup. The MS includes the NAS PDU in the RRC Connection complete message and sends it to eNB2. The NAS PDU includes a Bearer Resource ID in case of a small data fast path and a Connection ID in case of a connectionless data transmission. If the eNB 2 transmits information to the S-GW in the same manner as when the UE transmits the small amount of data, the S-GW knows that the UE has moved to another cell and can transmit downward small amount of data to the eNB 2.

When a cell camped on by a terminal is changed in the middle of performing a small amount of data transmission, the terminal updates the changed cell information on the network, thereby reducing the signaling overhead caused by performing paging several times.

7 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.

Referring to FIG. 7, a base station 1000 according to another embodiment includes a control unit 1010, a transmission unit 1020, and a reception unit 1030.

When the cell on which the terminal camp-on is changed in the middle of performing the small amount data transmission necessary for carrying out the present invention described above, the terminal updates the changed cell information to the network, And controls the overall operation of the base station according to the reduction of the signaling overhead caused by the performance of the base station.

The transmitting unit 1020 and the receiving unit 1030 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention to and from the terminal.

FIG. 8 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

Referring to FIG. 8, a user terminal 1100 according to another embodiment includes a receiving unit 1110, a control unit 1120, and a transmitting unit 1130.

The receiving unit 1110 receives downlink control information, data, and messages from the base station through the corresponding channel.

In addition, when the cell on which the terminal camp-on is changed in the middle of performing the small amount of data transmission necessary for carrying out the present invention described above, the terminal updates the changed cell information to the network, And controls the overall operation of the terminal according to the reduction of the signaling overhead caused by the execution of the signaling times.

The transmission unit 1130 transmits downlink control information, data, and a message to the base station through the corresponding channel.

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

1. 3GPP TR 23.887

2. 3GPP TS 36.331

3. 3GPP TS 36.300

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

Claims (1)

A method for updating a cell in a small amount of data transmission in which a terminal updates changed cell information to a network when a cell on which the terminal camp-on is changed in the middle of performing a small amount of data transmission.

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