[0001]
　The present disclosure relates to wireless communications, and more particularly to forwarding user data packets between base stations.
Background technique
[0002]
　3rd Generation Partnership Project (3GPP) Release 12 defines the X2 Gateway (X2 GW) (for example, see Non-Patent Document 1). As described in Non-Patent Document 1, X2 GW establishes a plurality of (H) each eNB and signaling (ie, Stream Control Transmission Protocol (SCTP)) connection, a plurality (H) eNB is the signaling message via the X2 GW (ie, X2AP message) to exchange. (H) eNB refers to eNodeB or Home eNodeB. X2 GW, except X2AP Message Transfer procedure, does not terminate the X2AP procedures The. That, X2AP context (X2AP contexts) is (as if X2 GW is not) that only exist in the two peers (H) eNB. X2AP context defines the "X2AP association" between spans two SCTP connection (spans-over-) two peers (H) eNB.
[0003]
　Transfer procedure X2AP messages by X2GW (X2AP Message Transfer procedure) is carried out as follows. That is, when transmitting a source (H) eNB is (except X2AP MESSAGE TRANSFER message) X2AP message to the target (H) eNB via the X2 GW, the source (H) eNB is, X2AP MESSAGE TRANSFER message the X2AP message encapsulates (encapsulate) within, to add the routing information (ie, RNL Header), and transmits the X2AP mESSAGE TRANSFER message to the X2 GW. Routing information (ie, RNL Header) includes both the target (H) eNB ID and source (H) eNB ID. X2 GW routes the X2AP MESSAGE TRANSFER messages based on the target (H) eNB ID.
[0004]
　Incidentally, X2 interface is an inter-base station interface since 3GPP Release 8. X2 interface includes a control plane (signaling) interface (ie, X2-C interface) and user plane (data plane) interface (ie, X2-U interface). X2-C interface, for example, prepare for handover between base stations (ie, X2 handover), the control of the Dual connectivity (eg, establishment of the UE context, modifications and open, and X2 user plane tunnel management), and neighboring eNB It is used for various settings and maintenance related. X2-C interface is configured to use the X2AP protocol uses SCTP and Internet Protocol (IP) to transfer X2AP signaling message. X2AP protocol is referred to as Radio Network Layer (RNL) protocol, SCTP / IP for transferring X2AP protocol is referred to as Transport Network Layer (TNL) protocol.
[0005]
　On the other hand, X2-U interface, for example, from a source (H) eNB during handover target (H) for forwarding user data packets to the eNB, and Master eNB (MeNB) and Secondary eNB in ​​Dual connectivity (SeNB) user data packets between for transferring (ie, packet data Convergence Protocol (PDCP) PDUs), are used. X2-U interface, using the GPRS Tunnelling Protocol User Plane (GTP-U) protocol using the User Datagram Protocol (UDP) and IP to transfer GTP Protocol Data Unit (GTP-PDU). GTP-U protocol is the RNL protocol user plane (U-plane), UDP / IP for transferring the GTP-U PDU is the TNL protocol for U-plane. GTP-U and TNL UDP / IP provides a tunnel mechanism. That, GTP-U, the user data packets (eg, IP packets) was encapsulated by GTP-U header, user data packet (ie, GTP-PDU) encapsulated is transferred in TNL UDP / IP layer . The user data packet may also be referred to as T-PDU. The user data packet (T-PDU) encapsulated by GTP-U header is one of the GTP-PDU, in order to distinguish the GTP-PDU including signaling messages between GTP node G- It may also be referred to as a PDU. Moreover, GTP-U PDU as G-PDU or signaling messages, sometimes referred to as GTP-U message.
[0006]
　As described in Non-Patent Document 1, 3GPP Release 12 is defines the X2AP transfer signaling message (X2-C) via the X2 GW between two peers (H) eNB, the user It does not specify the transfer of data packets (X2-U). In contrast, Patent Documents 1 and 2 disclose the transfer of user data packets through the X2 GW between two peers (H) eNB.
[0007]
　Patent Document 1, the core network (ie, Evolved Packet Core (EPC)) and (H) HeNB-GW to relay S1-MME signaling messages and user data packets between the eNB, X2-C interface and X2-U It has described that also support interface. HeNB-GW described in Patent Document 1 operates to relay GTP-PDU (ie, G-PDU), which encapsulates the user data packets between two peers (H) eNB. However, Patent Document 1 does not describe details of the relay operation of the G-PDU by HeNB-GW.
[0008]
　Patent Document 2 describes that the G-PDU is transferred via the X2-GW between the two (H) eNB. X2-GW of Patent Document 2, assigns a Tunnel Endpoint Identifier (TEID) to two (H) eNB during handover preparation, GTP-U TEID in the header of the GTP-U PDU received from one (H) eNB change the, operable to transmit the changed GTP-U PDU TEID to the other (H) eNB.
CITATION
Patent Literature
[0009]
Patent Document 1: JP 2012-227974 Patent Publication
Patent Document 2: JP 2013-150204 JP
Non-Patent Document
[0010]
非特許文献1 : 3GPP TS 36.300 V12.4.0 (2014-12), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 12)”, 2014年12月
Summary of the Invention
Problems that the Invention is to Solve
[0011]
　If the base station between the gateway (eg, X2-GW) is used, DL when the user data packets between the base station (eg, PDCP PDUs) transfer (eg, inter-base station handover (eg, X2 handover) data forwarding, and transfers between MeNB and SeNB in ​​Dual connectivity) is may not be appropriate at all times be performed via the X2-GW. For example, if the maximum or effective throughput of the base station between the direct path (eg, X2 interface) (transmission speed) is sufficiently large, always utilizing the relay by gateway between base stations appropriate in view of the increase in delay might not. On the other hand, when the load of the direct path between the base stations is high, or if the base station between the direct path is unavailable for any reason, it may be preferable to be able to select a relay by a gateway between the base stations. Also, two base stations (eg, (H) eNBs) during handover between, it may be preferable to be concealed TNL address (eg, IP address) of the one base station from other base stations. The TNL concealment of addresses, may be only request to the base station of the particular base station or particular type.
[0012]
　Accordingly, the base station (eg, (H) eNB) or a base station between the gateway (eg, X2-GW), the base station between the gateway upon the transfer of user data packets between the base station (eg, X2-GW) it may be preferable to choose whether or not to perform a relay process by. However, Patent Documents 1 and 2 does not describe that controls whether or not to perform a relay process by X2 GW. Here, the relay processing of the user data packet by the base station between the gateway (eg, X2-GW), the base station via the X2 GW (eg, (H) eNBs) means the transfer of user data packets between.
[0013]
　One objective to be achieved is the embodiment disclosed herein, a base station (eg, (H) eNB) or a base station between the gateway (eg, X2-GW) is the base station between the gateway (eg, X2-GW) contributes to make it possible to select whether or not to perform a relay process by the device is to provide a method, and a program. This purpose should embodiment disclosed herein is noted that only one of a plurality of objects to be achieved. Other objects or problems and novel features will become apparent from the description, or the accompanying drawings of this specification.
Means for Solving the Problems
[0014]
　In a first aspect, the base station apparatus includes a memory, and at least one processor coupled to said memory. Wherein the at least one processor is configured to transmit the first information element in the base station between the gateway. Wherein the first information element, whether or not the relay process of the data packet from the wireless terminal addressed or the wireless terminal a gateway between the base station and relays between the base station device and another base station is required explicitly or implicitly shown.
[0015]
　In a second aspect, between the base station gateway apparatus includes a memory, and at least one processor coupled to said memory. Wherein the at least one processor is configured to receive a first information element from the first at least one base station and a second base station. The first information element is required relay process of relaying between said second base station and the first base station the data packet by the base station between the gateway apparatus from the radio terminal addressed or the wireless terminal explicitly or implicitly indicate a whether the.
[0016]
　In a third aspect, a method performed by the base station apparatus, includes transmitting a first information element in the base station between the gateway. Wherein the first information element, whether or not the relay process of the data packet from the wireless terminal addressed or the wireless terminal a gateway between the base station and relays between the base station device and another base station is required explicitly or implicitly shown.
[0017]
　In a fourth aspect, a method performed by between base station gateway apparatus includes receiving from at least one of the first information element first base station and second base station. The first information element is required relay process of relaying between said second base station and the first base station the data packet by the base station between the gateway apparatus from the radio terminal addressed or the wireless terminal explicitly or implicitly indicate a whether the.
[0018]
　In a fifth aspect, the program includes the when loaded into a computer, instructions for performing the method according to the third or fourth aspects described above to a computer (software code).
Effect of the invention
[0019]
　According to the above aspects, it provides the base station or the base station between the gateway contributes device to be able to select whether or not to perform a relay process by the gateway between the base stations, a method, and a program.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020]
It is a diagram illustrating a configuration example of a wireless communication system according to [1] some embodiments.
[2] is a sequence diagram showing an example of a procedure for notifying the necessity of the relay processing according to the first embodiment.
3 is a flowchart showing an example of the operation of the source base station according to the first embodiment.
4 is a flowchart showing an example of the operation of the base station between the gateway according to the first embodiment.
5 is a flowchart showing an example of the operation of the target base station according to the first embodiment.
6 is a flowchart showing an example of the operation of the target base station according to the first embodiment.
7 is a table showing an example of a combination of operation and its start condition of the source base station and a base station between the gateway according to the first embodiment.
8 is a table showing an example of a combination of operation and its start condition of the source base station and a base station between the gateway according to the first embodiment.
9 is a table showing an example of a combination of operation and its start condition of the target base station and a base station between the gateway according to the first embodiment.
FIG. 10 is a table showing an example of a combination of operation and its start condition of the target base station and a base station between the gateway according to the first embodiment.
11 is a sequence diagram showing an example of a notification procedure of the relay capability according to the first embodiment.
12 is a sequence diagram illustrating an example of a notification procedure of the relay capability according to the first embodiment.
[FIG. 13A] is a sequence diagram illustrating an example of a base station handover procedure according to the first embodiment.
[FIG. 13B] is a sequence diagram illustrating an example of a base station handover procedure according to the first embodiment.
Is a diagram showing an example of the change in [Figure 14] X2AP Message Transfer Message (modification).
It is a diagram showing another example of the change in [Figure 15A] X2AP Message Transfer message.
It is a diagram showing another example of the change in [Figure 15B] X2AP Message Transfer message.
16 is a sequence diagram showing an example of a procedure for notifying the address of the third base station between the gateway according to the embodiment of the target base station.
[FIG. 17A] is a diagram showing an example of the change of X2 TNL Configuration Info message.
[FIG. 17B] is a diagram showing an example of the change of X2 TNL Configuration Info message.
18 is a block diagram showing an exemplary configuration of a base station according to some embodiments.
Is a block diagram showing an exemplary configuration of a base station between the gateway according to [19] Some embodiments.
DESCRIPTION OF THE INVENTION
[0021]
　Hereinafter, specific embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, for clarity of description, repeated explanation is omitted as appropriate.
[0022]
　A plurality of embodiments shown below is described a Long Term Evolution (LTE) / LTE-Advanced system as the main target. However, these embodiments, LTE / LTE-Advanced is not limited to the system, other wireless communication network or system, for example, 3GPP Universal Mobile Telecommunications System (UMTS), 3GPP2 CDMA2000 systems, Global System for Mobile communications ( GSM (TM)) / General packet radio service (GPRS) system, and may be applied to WiMAX systems.
[0023]

　FIG 1 shows a configuration example of a wireless communication system according to some embodiments including the present embodiment. In the example of FIG. 1, a wireless communication system includes a (H) eNB1, (H) eNB2, X2 GW3, and EPC4. X2 GW 3 is to relay signaling messages (X2AP messages) between the (H) eNBs1 and 2, is configured to establish each and SCTP connection (H) eNBs1 and 2. X2 GW 3 is further configured to establish a (H) eNBs1 and for relaying user data packets between 2, (H) eNBs1 and 2 each and GTP-U tunnel. (H) eNBs1 and 2 each having the X2-C interface between the X2 GW 3, has a S1 interface between the EPC4. It may also be used HeNB-GW between at least one and EPC4 of (H) eNB1 and 2. The HeNB-GW relays (H) eNB1 and 2 at least one and S1-MME signaling and user data packets between EPC4 (S1-U). In the present embodiment, it will be described mainly UE handover of (H) from eNB1 to (H) eNB2. Accordingly, (H) eNB1 is referred to as the source (H) eNB, sometimes called the target (H) eNB (H) eNB2 .
[0024]
　In the present embodiment, it is configured to transmit (H) of at least one of eNBs1 and 2, a first information element (Information Element (IE)) of the X2 GW 3. The first piece of information is explicitly or implicitly indicate whether a relay process by X2 GW 3 for forwarding user data packets of the wireless terminal (User Equipment (UE)) is required. In some implementations, when (H) from the eNB1 of the UE for handover to (H) eNB2, at least one of the source (H) ENBs1 and target (H) eNB2 is transmitted the first information element it may be. In some implementations, (H) eNB1, (H) eNB2, and if the UE supports Dual Connectivity, upon bearer establishment of the UE, (H) eNBs1 and (H) eNB2 of at least one of the it may transmit the first information element.
[0025]
　X2 GW 3 relay processing by the, (H) eNB1 and X2 GW3 X2-U interface between the (GTP-U tunnel) 101, and (H) eNB2 and X2 GW3 X2-U interface between the (GTP-U tunnel) comprising transferring user data packets (T-PDU) through 102. Relay of the user data packet by X2 GW 3 is the relay process may be performed by transferring user data packets encapsulated by GTP-U header, i.e. the G-PDU. X2 GW 3 relay processing by the, X2-U relay, U-plane relay, GTP-U relay, or can also be referred to as user plane aggregate (user plane concentration).
[0026]
　That is, the first piece of information is explicitly indicate the need for U-plane relay by X2 GW3 (explicit) or implicit (implicits) display (indication). In some implementations, the display may be a flag information different values ​​depending on whether the relay processing by X2 GW 3 is required is set. Alternatively, in some implementations, the display is an explicit or implicit relay request and relay processing is sent when is not transmitted when it is unnecessary relay processing by X2 GW 3 is required it may be. Alternatively, in some implementations, the display may also be a combination of a plurality of information elements.
[0027]
　For example, as in the embodiment shown below, the display may comprise (H) eNBs1 and information element indicating availability of the direct path 100 between 2 (eg, Direct Path Availability IE or Direct Path Unavailability IE) But good. Availability of direct path 100 is, for example, by the operator, i.e. operations, the administration and maintenance (OAM), may be pre-set to (H) eNBs1 and 2. Alternatively, availability of the direct path 100 may be dynamically determined by the (H) eNBs1 and 2. For example, (H) eNBs1 and 2, if it can use the direct path 100 its throughput is low, or when the load of the direct path 100 is high, it may be determined not available direct path 100. The display may, for example, may be a combination of information elements indicating the necessity of the information element and data forwarding indicating the availability of the direct path 100 (eg, DL Forwarding IE or Uplink (UL) GTP Tunnel Endpoint IE).
[0028]
　Figure 2 is a sequence diagram showing an example of a procedure for notifying the necessity of relay processing X2 GW 3 (the processing 200). In block 201, (H) eNB1 or 2 transmits X2AP Message Transfer message to the X2 GW 3. The X2AP Message Transfer message carries X2AP Handover Request Acknowledge message from X2AP Handover Request message or target (H) eNB2 from the source (H) eNB1 to the target (H) eNB2 to the source (H) eNB1. The X2AP Message Transfer message further includes explicitly or implicitly indicate display the need for X2-U relay processing by the X2 GW 3. X2 GW 3, based on the display, it is possible to recognize whether or not to perform preparation for X2-U relay.
[0029]
　In the example of FIG. 2, X2 GW 3, together with X2AP Message Transfer message carrying the Handover Request message or Handover Request Acknowledge message, receiving an indication indicating a need for X2-U relay process. Accordingly, X2 GW 3, by referring to the X2AP Message Transfer message, it is possible to easily prepare for GTP-U tunnels required X2-U relay.
[0030]
　As understood from the above description, in the present embodiment, (H) eNBs1 and at least one of the two explicitly or whether the U-plane (X2-U) relay by X2 GW 3 is required a display implicitly shown is configured to transmit the X2 GW 3. Accordingly, X2 GW 3, based on the display, it is possible to recognize whether or not to perform the U-plane (X2-U) relay.
[0031]
　Furthermore, in the present embodiment, (H) ENBs1 and at least one of 2, which is required transfer of user data packets (H) wireless terminal from eNB1 to (H) eNB2 (UE), the UE it may be configured to determine whether to use the relay processing by X2 GW 3 for forwarding user data packets. In other words, either the (H) ENBs1 and 2, (H) from eNB1 (H) Rirepasu (101 and 102) via the X2 GW 3 for forwarding user data packets to the eNB2 and direct path (100) it may be configured to select whether to use. If by X2 GW 3 does not use the relay process, the source (H) eNB1, the direct path between the (H) ENBs1 and 2, that is, the user data packet using the X2-U interface (GTP-U tunnel) 100 Target ( H) eNB2 may be forwarded to.
[0032]
　In some implementations, the source (H) eNB1 is whether to use the case, U-plane (X2-U) by X2 GW 3 relay processing to determine the start of the UE handover to (H) eNB2 it may be determined. In some implementations, the target (H) eNB2, when receiving a handover request from a source (H) eNB1, determines whether to use the U-plane (X2-U) relay processing by the X2 GW 3 it may be. In some implementations, (H) eNB1 a request bearer establishment for the UE that supports Dual connectivity (eg, S1AP: Initial Context Setup Request) when receiving from EPC4, by X2 GW3 U-plane (X2- U) may determine whether to use the relay process. Instead of them, whether to use the U-plane (X2-U) relay processing by the X2 GW 3, it may be pre-determined for each pair of (H) eNB.
[0033]
　In some implementations, depending on the (H) eNB1 or 2 or both, the state of the direct path 100 (eg, availability of direct path 100, the throughput of the direct path 100, or the load of the direct path 100), X2 U-plane by GW3 (X2-U) may be selected whether to use the relay process. In other words, in determining the (H) eNB1 or 2 or both are, X2 by GW3 U-plane (X2-U) whether to use a relay process (whether or requests), the direct path 100 the state may be taken into account.
[0034]
　For example, larger than the throughput of the maximum or effective throughput between the base station direct path 100 (transmission speed) (H) eNB1 (or 2) a path 101 between the X2 GW 3 (or 102), between the base stations utilizing relay by gateway may not be appropriate in view of the increase in delay. Accordingly, (H) eNB1 or 2, when the throughput between the base station direct path 100 (H) eNB1 and X2 is sufficiently larger than the throughput of the path 101 or 102 between the GW 3, according to the X2 GW3 U-plane ( X2-U) may decide not to use the relay process. This can suppress an increase in the delay due to unnecessary U-plane relay.
[0035]
　In some implementations, (H) eNB1 is, (H) eNB1 TNL address (eg, IP address) by X2 GW 3 when it is necessary to conceal from (H) eNB2 U-plane (X2-U) Relays processing using the forwarding via the direct path 100 may be carried out if it is not required concealment of TNL address. Similarly, (H) eNB2 is, (H) eNB2 TNL address (eg, IP address) on the basis of the need for concealment from (H) eNB1, U-plane (X2-U) relay processing by the X2 GW 3 You may choose whether or not to use. In other words, (H) eNB1 or 2 or both, in determining the U-plane by X2 GW 3 (X2-U) whether (or whether to request) use a relay process, the TNL address the need for concealment may be taken into account.
[0036]
　For example, the source (H) eNB1, when the handover, may require to be concealed TNL own address (eg, IP address) from the target (H) eNB2. On the contrary, it may be the target (H) eNB2 needs to be concealed the TNL address (eg, IP address) from the source (H) eNB1. The TNL concealment of addresses, may be only request to the base station of the particular base station or particular type.
[0037]
　HeNB is not in the office building that is managed by the communication company (site), it can be installed in the end-user of the house or building. Therefore, HeNB is risk of being modified by a malicious user, not necessarily security is fully guaranteed apparatus. Therefore, when the handover is to inform the X2-U TNL address of the macro eNB for such HeNB, there is a risk that the macro eNB may lead to security risks, such as receiving a Denial of Service (DoS) attacks. For example, determining that the source (H) eNB1 a target (H) eNB2 a macro eNB may be HeNB, the source (H) eNB1 is to use the U-plane (X2-U) relay processing by the X2 GW 3 it may be. On the other hand, if the source (H) eNB1 is a macro eNB and a by target (H) eNB2 also macro eNB, the source (H) eNB1 is not to use the U-plane (X2-U) relay processing by the X2 GW 3 it may be determined. This can suppress the security risk due to inform the X2-U TNL address of the macro eNB to HeNB.
[0038]
　In some implementations, the (H) eNB1 or 2 or both are, X2 GW 3 based on the U-plane relay capability (U-plane Relay Capability) of, U-plane (X2-U) by X2 GW 3 relay processing You may choose whether or not to use. In other words, (H) eNB1 or 2 or both, in determining whether to use the U-plane (X2-U) relay processing by the X2 GW 3 (or whether to request), the X2 GW 3 the presence or absence of a U-plane relay capability may be taken into consideration.
[0039]
　As understood from the above description, in the present embodiment, (H) eNBs1 and at least one of 2, (H) when the eNB1 of the UE handover to (H) eNB2, U-plane by X2 GW 3 (X2-U) may be configured to determine whether to use the relay process. Thus, at least one of (H) eNBs1 and 2 can be selected whether to use the U-plane (X2-U) relay processing by the X2 GW 3.
[0040]
　Then hereinafter, source (H) eNB1, X2 GW3, and illustrating a specific example of the operation of the target (H) eNB2. Figure 3 is a flowchart showing a source (H) an example of the operation of the eNB1 (process 300). In block 301, (H) eNB1 determines the start of a UE handover to the target (H) eNB2. In block 302, the time of the handover, it is determined whether U-plane by X2 GW3 (X2-U) relay processing is required. If U-plane (X2-U) relay processing is required (YES at block 302), a source (H) eNB1 a handover request (ie, Handover Request message) to carry forward the message (ie, X2AP Message Transfer Message ) to include an explicit or implicit relay request (block 303). In block 304, the source (H) eNB1 transmits forward message carrying a handover request (including the relay request) to X2 GW 3. In contrast, if the U-plane (X2-U) relay processing is not required, the (NO at block 302), a source (H) eNB1 is (without relay request) Transfer message carrying a handover request X2 and it transmits to the GW 3 (block 305).
[0041]
　Figure 4 is a flow chart showing an example of the operation of the X2 GW 3 (the processing 400). In block 401, X2 GW 3 receives the handover request (ie, Handover Request message) to carry forward message (ie, X2AP Message Transfer message) from a source (H) eNB1. At block 402, X2 GW 3 checks whether contains relay request received transfer message. If the transfer message includes a relay request (YES at block 402), X2 GW 3 adds an indication that the U-plane (X2-U) relay by X2 GW 3 is performed in the transfer message (carrying the handover request) , and transmits to the target (H) eNB2.
[0042]
　In some implementations, X2 GW 3 in accordance U-plane (X2-U) the indicates that the relay is carried out display is a simple flag information indicating whether U-plane (X2-U) relay is performed it may be. Additionally or alternatively, as shown in block 403 of FIG. 4, X2 GW 3 in accordance U-plane (X2-U) the display to indicate that the relay is performed, X2 transport bearers (ie, GTP -U bearer) relates may include an endpoint settings X2 GW 3 side. Endpoint configuration includes TNL address (eg, IP address) to and TEID. The endpoint configuration may be a DL GTP tunnel endpoint set only relates X2 transport bearer to be used for forwarding the downlink (DL) user data packets are used for forwarding the uplink (UL) user data packets that X2 may further include a UL GTP tunnel endpoint settings for transport bearer.
[0043]
　X2 GW 3 is, together with the forwarded message carrying the handover request by sending X2 transport bearer (ie, GTP-U bearer) endpoint settings for X2 GW 3 side to the target (H) eNB2, the effect described below, for example can get. In some implementations, the target (H) eNB2 might have an Access Control List (ACL) Function (Functionality). If the ACL function is applied to the target (H) eNB2, the target (H) eNB2 only if you already know in the source address of the sending node target (H) eNB2, accepts a connection from a sending node. Therefore, unless if knowing the X2-U TNL address of the target (H) eNB2 is X2 GW 3, the target (H) eNB2 is by ACL function TNL UDP / IP packets carrying G-PDU transmitted from the X2 GW 3 there is a discarded fear. To avoid this, X2 GW 3 is a upstream data forwarding, notification ahead X2 transport bearers (ie, GTP-U bearer) endpoint settings for X2 GW 3 side to the target (H) eNB2 Then good. Thus, the target (H) eNB2 can update the ACL to accept connections from X2-U TNL address X2 GW 3. ACL can also be referred to as a packet filter or firewall settings.
[0044]
　Continuing with the description back to FIG. 4. If the forwarded message does not contain the relay request (NO at block 402), X2 GW 3 transmits the transfer message received from the source (H) eNB1 as it is to the target (H) eNB2 (block 404). In other words, the transfer message sent in block 404 does not include an indication that the U-plane (X2-U) relay by X2 GW 3 is performed.
[0045]
　Figure 5 is a flow chart showing an example of the operation of the target (H) eNB2 the (process 500). In block 501, the target (H) eNB2 a handover request (ie, Handover Request message) to carry forward the message (ie, X2AP Message Transfer message) is received from the X2 GW 3. At block 502, the transfer message received determines whether including the X2 transport bearers (ie, GTP-U bearers) relates X2 GW 3 endpoint settings. If X2 GW 3 endpoint settings are included (YES at block 503), the target (H) eNB2 updates its ACL to accept connections from X2-U TNL address X2 GW 3.
[0046]
　At block 504, the target (H) eNB2 sends a handover request acknowledge (ie, Handover Request Acknowledge message) to carry forward the message (ie, X2AP Message Transfer message) to the X2 GW 3. Handover request acknowledge (ie, Handover Request Acknowledge message) includes a DL GTP tunnel endpoint setting a target (H) eNB2. Furthermore, if the UL data forwarding is performed in addition to the DL data forwarding, a handover request acknowledge (ie, Handover Request Acknowledge message) includes a UL GTP tunnel endpoint setting a target (H) eNB2. DL GTP tunnel endpoint setting a target (H) eNB2 includes TNL address and TEID about GTP-U tunnel for receiving the DL user data packets forwarded from the source (H) eNB1. UL GTP tunnel endpoint setting a target (H) eNB2 includes TNL address and TEID about GTP-U tunnel for receiving UL user data packets forwarded from the source (H) eNB1.
[0047]
　The transfer message carrying a handover request acknowledge message sent at block 504, an additional information element indicating the same target (H) eNB2 GTP tunnel endpoint settings as described in the handover request acknowledge message it may also include a. Although such messages configuration is redundant, there is an advantage that X2 GW 3 may not decode or reference to the handover request acknowledge message.
[0048]
　FIGS. 3 to the source shown in 5 (H) eNB1, X2 GW3, and the target (H) Operation of eNB2 may be appropriately changed merely an example. For example, a message used to send the relay request in Figure 3, may be a different X2AP message and X2AP Message Transfer message. For example, the relay request may be set to Handover Request message carried by X2AP Message Transfer message. 4, the message used to send the end-point configuration X2 GW 3 may be different X2AP message and X2AP Message Transfer message. For example, X2 endpoint settings GW3 may be set to Handover Request message carried by X2AP Message Transfer message.
[0049]
　3 to 5, when the handover request, for example of determining a source (H) eNB1 is whether to use the U-plane (X2-U) Relay whether (whether or requests) by X2 GW 3 Indicated. Similarly, when the handover request is received via the X2 GW 3 from the source (H) eNB1, the target (H) eNB2 is a U-plane (X2-U) relay source (H) eNB1 is due to X2 GW 3 whether to use the (or whether to request) may be determined. In other words, independently of the U-plane (X2-U) necessity determination of the relay by X2 GW 3 by source (H) eNB1, the target (H) eNB2 is, X2 GW 3 in accordance U-plane (X2-U) main relay It not may be determined.
[0050]
　Figure 6 is a flowchart showing a target (H) U-plane (X2-U) an example of the operation including the necessity determination of the relay to be performed by the eNB2 (process 600). In block 601, the target (H) eNB2 a handover request (ie, Handover Request message) to carry forward the message (ie, X2AP Message Transfer message) is received from the X2 GW 3. At block 602, the target (H) eNB2 determines whether U-plane by X2 GW3 (X2-U) relay processing is required. If U-plane (X2-U) relay processing is required (YES at block 602), the target (H) eNB2 a handover request acknowledge (ie, Handover Request Acknowledge message) to carry forward the message (ie, X2AP Message Transfer message) to include an explicit or implicit relay request (block 603). At block 604, the target (H) eNB2 transmits forward message carrying a handover request acknowledge (including relay request) to X2 GW 3. In contrast, if the U-plane (X2-U) relay processing is not required, the (NO at block 602), the target (H) eNB2 is (without relay request) Transfer message carrying a handover request acknowledge and transmits the X2 GW 3 (block 605).
[0051]
　A transfer message carrying a handover request acknowledge (including relay request) operation of X2 GW 3 when receiving from the target (H) eNB2, may be similar to FIG. However, as discussed with respect to FIG. 5, the handover request acknowledge (ie, Handover Request Acknowledge message) includes a GTP tunnel endpoint setting a target (H) eNB2. In some implementations, the process corresponding to block 403, X2 GW 3 is a GTP tunnel endpoint setting a target (H) eNB2 described in the Handover Request Acknowledge message, X2 GW 3 GTP tunnel endpoint it may be rewritten by the setting.
[0052]
　Alternatively, in a process corresponding to block 403, X2 GW 3 is without modification to the GTP tunnel endpoint setting a target (H) eNB2 described in the Handover Request Acknowledge message, X2 GW 3 End additional information element indicating point settings may be included in X2AP message Transfer message. In this case, the source (H) eNB1 updates the X2 transport bearer context according additional information elements, ignoring the GTP tunnel endpoint setting a target (H) eNB2 described in the Handover Request Acknowledge message good.
[0053]
　However, if the U-plane by X2 GW3 (X2-U) relay is made to conceal TNL address of the target (H) eNB2 from the source (H) eNB1, X2 GW3 are described in Handover Request Acknowledge message and has it is preferable to modify the GTP tunnel endpoint setting a target (H) eNB2. Thus, it is possible to conceal from the source (H) eNB1 of TNL address of the target (H) eNB2 reliably.
[0054]
　3 to 6, (H) eNB1 in handover, showing a specific example of the operation of the (H) eNB2, and X2 GW 3. However, as will be understood from the already described, FIGS. 3-6 have been described with reference to (H) eNB1, a specific example of the operation of the (H) eNB2, and X2 GW 3 is, UE supporting Dual connectivity it may be applied when performing a bearer establishment related. For example, whether to use in response, the U-plane (X2-U) relays treatment with X2 GW 3 in (H) eNB1, it receives a request for bearer establishment for the UE to support the Dual connectivity from EPC4 it may be determined. Then, (H) eNB1, the transfer message (ie, X2AP Message Transfer message) carrying X2AP message for establishing the UE context for Dual connectivity may include an explicit or implicit relay request.
[0055]
　Then, in the following, a specific example of the operation and its start condition of the source (H) eNB1 and X2 GW 3 will be described with reference to FIGS. Figure 7 is a table showing an example of a combination of operation and its start condition of the source (H) eNB1 and X2 GW 3. In the example of FIG. 7, the source (H) eNB1 is, U-plane (X2-U) to determine whether to use the relay (or whether to request), availability of the direct path 100 (Direct Path Availability) and be referred to X2 GW 3 relay capability (U-plane relay capability).
[0056]
　Case 1 shown in FIG. 7 is a direct path 100 is available, a case where X2 GW 3 has a relay capability. Case 2 shown in FIG. 7, available direct path 100, X2 GW 3 is a case that does not have a relay capability. In cases 1 and 2, since the direct path 100 is available, source (H) eNB1 does not set explicitly or implicit relay request X2AP Message Transfer message for X2 GW 3 (carrying Handover Request message) . Accordingly, X2 GW 3 does not implement U-plane (X2-U) Relay relating DL data forwarding.
[0057]
　Case 3 shown in FIG. 7 is a direct path 100 is not available, a case where X2 GW 3 has a relay capability. In Case 3, although direct path 100 is not available, X2 GW 3 for having a relay capability, the source (H) eNB1 is explicit or implicit relay request X2AP Message Transfer message for X2 GW3 (Handover Request Message It is set to a carry). Accordingly, X2 GW 3 performs a U-plane (X2-U) Relay relating DL data forwarding.
[0058]
　Case 4 shown in FIG. 7 is a direct path 100 is not available, and X2 GW 3 is a case that does not have a relay capability. In Case 4, since it is impossible to X2-U data forwarding, a source (H) eNB1 does not set explicitly or implicit relay request X2AP Message Transfer message for X2 GW 3 (carrying Handover Request message). Accordingly, X2 GW 3 does not implement U-plane (X2-U) Relay relating DL data forwarding.
[0059]
　As previously described, in some implementations, implicit relay request for X2 GW 3 (or relay Display) may include a combination of a plurality of information elements. For example, as shown in Figure 8, implicit relay request for X2 GW 3 (or relay display) may also be a combination of Direct Path unavailability IE and DL Forwarding IE. Direct Path unavailability IE shown in FIG. 8 is set when the direct path 100 is not available. Direct Path unavailability IE may be 1-bit flag information. DL Forwarding IE shown in FIG. 8, X2AP in the current 3GPP Specification: Handover may be a DL Forwarding IE included in the Request message, there in information element is newly added to X2AP Message Transfer Message it may be.
[0060]
　Cases 1 to 4 shown in FIG. 8, corresponding respectively to the cases 1 to 4 shown in FIG. In other words, the case 1 shown in FIG. 8 are available direct path 100 is a case where X2 GW 3 has a relay capability. Case 2 shown in FIG. 8, available direct path 100, X2 GW 3 is a case that does not have a relay capability. In cases 1 and 2, since the direct path 100 is available, source (H) eNB1 does not set the Direct Path Unavailability IE. On the other hand, in order to inform the target (H) eNB2 to perform a DL forwarding (via the direct path 100), sets the DL Forwarding IE.
[0061]
　Case 3 shown in FIG. 8 is a direct path 100 is not available, a case where X2 GW 3 has a relay capability. In Case 3, for the direct path 100 is not available, to set the Direct Path Unavailability IE. Furthermore, since although not available direct path 100 X2 GW 3 has a relay capability, the source (H) eNB1 determines that it is possible DL forwarding via the X2 GW 3, thus (via the X2 GW 3) DL to signal that performs forwarding to the target (H) eNB2, sets the DL forwarding IE.
[0062]
　Case 4 shown in FIG. 8 is a direct path 100 is not available, and X2 GW 3 is a case that does not have a relay capability. Therefore, in case 4, the source (H) eNB1 sets the Direct Path unavailability IE, do not set the DL Forwarding IE.
[0063]
　In the example of FIG. 8, X2 GW 3 is, Direct Path unavailability reference to IE and DL Forwarding IE, they may be carried out U-Plane (X2-U) Relay relating DL data forwarding if they are both set. Therefore, as in the example of FIG 7, U-Plane (X2-U) relates to the case 3 only DL data forwarding FIG relay is performed, U-Plane about DL data forwarding in cases 1, 2 and 4 in FIG. 8 (X2-U) relay is not performed.
[0064]
　Then hereinafter be described with reference to FIGS. 9 and 10 for a specific example of the operation and its start condition of the target (H) eNB2 and X2 GW 3. Figure 9 is a table showing an example of a combination of operation and its start condition of the target (H) eNB2 and X2 GW 3. Example of FIG. 9 for the target (H) eNB2 corresponds to the example of FIG. 7 for the source (H) eNB1. Therefore, the embodiment is U-Plane (X2-U) Relay relating UL data forwarding only the case 3 of FIG. 9, U-Plane about UL data forwarding in cases 1, 2 and 4 in FIG. 9 (X2-U) relay implementation not.
[0065]
　In the example of FIG. 10, implicit relay request to the target (H) eNB2 X2 GW3 (or relay display) are a combination of Direct Path unavailability IE and UL GTP Tunnel Endpoint IE. UL GTP Tunnel Endpoint IE shown in FIG. 10, X2AP in the current 3GPP Specification: Handover Request Acknowledge may be a UL GTP Tunnel Endpoint IE included in the message, it is newly added to X2AP Message Transfer Message it may be an information element that.
[0066]
　Example of FIG. 10 for the target (H) eNB2, except the difference in DL Forwarding IE and UL GTP Tunnel Endpoint IE, corresponding to the example of FIG. 8 regarding the source (H) eNB1. That is, in the example of FIG. 10, X2 GW 3 is, Direct Path unavailability reference to IE and UL GTP Tunnel Endpoint IE, implement U-Plane (X2-U) Relay relating UL data forwarding if they are both set do it. Therefore, the embodiment is U-Plane (X2-U) Relay relating UL data forwarding only the case 3 of FIG. 10, U-Plane about UL data forwarding in cases 1, 2 and 4 in FIG. 10 (X2-U) relay implementation not.
[0067]
　7 to 10, (H) eNB1 in handover, showing a specific example of the operation of the (H) eNB2, and X2 GW 3. However, as will be understood from the already described, FIGS. 7 to 10 are described with reference to (H) eNB1, a specific example of the operation of the (H) eNB2, and X2 GW 3 is, UE supporting Dual connectivity it may be applied when performing a bearer establishment related.
[0068]
　Figure 7 is to 10 examples described with reference to, determine (H) eNB1 and (H) eNB2 is, U-plane (X2-U) whether (or whether to request) utilizing relay when, consider the existence of the relay capability of the X2 GW 3. Whether the relay capability of the X2 GW 3 are by the operator, i.e. operations, the administration and maintenance (OAM), may be pre-set to (H) eNBs1 and 2. Alternatively, X2 GW 3 may notify the presence or absence of its relay capability (H) eNBs1 and 2. That, X2 GW 3 may send a signaling message including an information element indicating the presence or absence of its relay capability (IE) (H) eNBs1 and 2. In some implementations, as shown in FIGS. 11 and 12, X2 GW 3 is in the procedure of registering the (H) eNBs1 and 2 to X2 GW 3, by knowing its relay capability (H) eNBs1 and 2 it may be.
[0069]
　Figure 11 is a sequence diagram showing an example (process 1100) procedure for notifying the existence of the relay capability from X2 GW 3 in (H) ENBs1 and 2. In block 1101, (H) eNBs1 (2) transmits a registration request to the X2 GW3 ((H) eNB registration). The registration request source (H) eNB included in the registration request identifier (ie, Global eNB ID) and the registration request transmission source that was used to send the (H) TNL address (eg, IP address) of the eNB to save the mapping. Then, in block 1102, X2 GW 3 transmits a response to the registration request ((H) eNB registration response). The response includes an information element (U-plane Relay Capability) indicating whether the relay capability of the X2 GW 3. (H) eNBs1 (2) by receiving the response at block 1102, recognizes the existence of U-plane (X2-U) relay capability of the X2 GW 3.
[0070]
　Figure 12 is a sequence diagram showing another example of a procedure for notifying the existence of the relay capability to the X2 GW3 (H) eNBs1 and 2 (processing 1200). In 3GPP Release 12, for registration in the X2 GW of (H) eNB, X2AP Message Transfer messages are used. Figure 12 shows an example of using the X2AP Message Transfer message like the 3GPP Release 12. That is, in block 1201, requests registration (H) eNB1 (2) include, but Source (H) eNB ID into RNL Header IE, free of Target (H) eNB ID into RNL Header IE, and to send a X2AP message Transfer messages that do not contain the X2AP message. In block 1202, X2 GW 3 transmits the X2AP Message Transfer messages that have been modified. The modified X2AP Message Transfer message, RNL Header in IE includes a Target (H) eNB ID, including the newly defined U-plane Relay Capability IE, Source (H) eNB ID into RNL Header IE not including, and transmits the X2AP message Transfer message without the X2AP message. (H) eNBs1 (2) by receiving the X2AP Message Transfer message in block 1202, recognizes the existence of U-plane (X2-U) relay capability of the X2 GW 3.
[0071]
　13A and 13B are sequence diagrams showing an example of the (process 1300) in X2 handover procedure according to the present embodiment. Procedure shown in FIGS. 13A and 13B, except the source that the forwarding of user data packets from the (H) eNB1 to the target (H) eNB2 is via X2 GW 3 (block 1307 and 1308), usually is the same as X2 handover procedure via the X2 GW of. That is, in block 1301, the source (H) eNB1 transmits the X2AP Message Transfer message carrying the Handover Request message to the X2 GW 3. As already explained, the X2AP Message Transfer message may include the explicitly or implicitly indicating the information element the necessity of U-plane (X2-U) relay. In block 1302, X2 GW 3 transfers the X2AP Message Transfer message carrying the Handover Request message to the target (H) eNB2. As previously described, X2 GW 3, depending on whether or not the U-plane (X2-U) relays may be updated information elements X2AP Message Transfer message at block 1302, information elements it may be added.
[0072]
　In block 1303, the target (H) eNB2 transmits X2AP Message Transfer message carrying the Handover Request Acknowledge message to the X2 GW 3. As already explained, the X2AP Message Transfer message may include the explicitly or implicitly indicating the information element the necessity of U-plane (X2-U) relay. In block 1304, X2 GW 3 transfers the X2AP Message Transfer message carrying the Handover Request Acknowledge message to the source (H) eNB1. As previously described, X2 GW 3, depending on whether or not the U-plane (X2-U) relays may be updated information elements X2AP Message Transfer message at block 1304, information elements it may be added.
[0073]
　Source (H) eNB1, in response to receiving the Handover Request Acknowledge message and sends handover command to the UE which is not illustrated (Handover Command). In block 1305, the source (H) eNB1 transmits the X2AP Message Transfer message carrying the SN Status Transfer message to the X2 GW 3. SN Status Transfer message indicates delivery to UE is not completed uplink / downlink Packet Data Convergence Protocol (PDCP) PDU of Sequence Number (SN). In block 1306, X2 GW 3 transfers the X2AP Message Transfer message carrying the SN Status Transfer message to the target (H) eNB2.
[0074]
　In block 1307 and 1308, a source (H) eNB1 is an uplink / downlink user data packet delivery is not completed to the UE, and forwarding to the target (H) eNB2 via the X2 GW 3. That is, in block 1307, the source (H) eNB1 via a GTP-U tunnel between the source (H) eNB1 and X2 GW 3, the G-PDU encapsulating the uplink / downlink user data packets to the X2 GW 3 Send. In block 1308, X2 GW 3 via a GTP-U tunnel between the target (H) eNB2 and X2 GW 3, and transfers the G-PDU received from the source (H) eNB1 to the target (H) eNB2.
[0075]
　Data forwarding blocks 1307 and 1308, X2GW3 the source (H) eNB1 source TNL address given to the G-PDU received from the TNL address of (ie, source (H) eNB1 TNL address) X2GW3 update and, a source TEID a (ie, the source (H) eNB1 TEID) of updating the TEID of X2GW3. Furthermore, X2GW3 is the source (H) eNB1 granted to G-PDU received from the target TNL address (ie, X2GW3 TNL address) is updated by TNL address of the target (H) eNB2, the target TEID (ie, the TEID) of X2GW3 be updated by the TEID of the target (H) eNB2.
[0076]
　In block 1309, the target (H) eNB2 receives a handover confirmation message (Handover Confirm) from the UE. Thus, UE is the target (H) eNB2 can transmit UL user data packet, can receive the DL user data packets from the target (H) eNB2.
[0077]
　In block 1310, the target (H) eNB2 to request the reroute Evolved Packet System (EPS) bearer with inform serving cell change of the UE in EPC4, S1AP: Path the Switch Request message EPC4 (i.e., Mobility Management to send to the Entity (MME) 5). MME5 is to signal a Serving Gateway (not shown) (S-GW), to correct the path of the EPS bearer (i.e., the path of the S1 bearer). In block 1311, MME5 is, S1AP: a Path Switch Request Acknowledge message sent to the target (H) eNB2. At block 1312, in response to receiving the Path Switch Request Acknowledge message, the target (H) eNB2 transmits X2AP Message Transfer message carrying the UE Context Release message to the X2 GW 3. In block 1313, X2 GW 3 transfers the X2AP Message Transfer message carrying the UE Context Release message to the source (H) eNB1. Source (H) eNB1, in response to receiving the UE Context Release message, releases the radio resources allocated to the UE.
[0078]
　Incidentally, the target (H) eNB2 in response to the transmission of the UE Context Release message (block 1312), may be opened to GTP-U tunnel setting for data forwarding. X2 GW 3, in response to receiving the X2AP Message Transfer message carrying the UE Context Release message (block 1312), may be opened to GTP-U tunnel setting for data forwarding. Source (H) eNB1, in response to receiving the UE Context Release message (block 1313), may be opened to GTP-U tunnel setting for data forwarding.
[0079]
　Then, in the following, a specific example of changes X2AP Message Transfer Message (modification), will be described with reference to FIGS. 14 and FIGS. 15A and 15B. Figure 14 shows an example of a change of X2AP Message Transfer message. "U-Plane Relay Capability" IE is used by the U-plane (X2-U) whether the relay capacity (H) eNBs1 and X2 to inform the 2 GW 3. "Direct Path Unavailability" IE is used by (H) eNBs1 and 2 in order to inform the availability of the direct path 100 to the X2 GW 3. "E-RABs To Be Setup List" IE is used by the X2 GW 3 to inform Endpoint settings X2 GW 3 to (H) eNBs1 and 2.
[0080]
　"E-RABs To Be Setup List" IE is, including the "E-RABs To Be Setup Item" IE. "E-RABs To Be Setup Item" IE is, including the "E-RAB ID" IE, "UL GTP Tunnel Endpoint" IE and, "DL GTP Tunnel Endpoint" IE. "UL GTP Tunnel Endpoint" IE indicates the UL data (UL PDUs) X2 Endpoint settings X2 GW 3 about the transport bearers for forwarding (i.e., TNL address and TEID). "DL GTP Tunnel Endpoint" IE indicates the DL data (DL PDUs) X2 Endpoint settings X2 GW 3 about the transport bearers for forwarding (i.e., TNL address and TEID).
[0081]
　15A and 15B illustrate another example of a change of X2AP Message Transfer message. As shown in FIG. 15A, X2AP Message Transfer message may be extended to include "Message Type of X2AP Message" IE. "Message Type of X2AP Message" IE indicates the type of X2AP message carried by X2AP Message Transfer message. Accordingly, X2 GW 3 may be operable to refer or decode only X2AP messages required. That, "Message Type of X2AP Message" when IE indicates Handover Request message or Handover Request Acknowledge message only, reference may be made or decode "X2AP message" IE in X2AP Message Transfer message.
[0082]
　Additionally or alternatively, as shown in FIG. 15B, X2AP Message Transfer message may be extended to include "DL Forwarding" IE. "DL Forwarding" IE is, "X2AP message" IE is when carrying Handover Request message is used by the source (H) eNB1. "DL Forwarding" IE indicates the "DL Forwarding" the same content as the IE included in the Handover Request message "X2AP message" in IE. Accordingly, X2 GW 3 is, "DL Forwarding" to confirm the IE "X2AP message" Handover Request message does not need to decode or see in the IE.
[0083]
　Following the same concept as this, X2AP Message Transfer message may be extended to include "E-RAB Level QoS Parameters" IE shown in Figure 15B. "E-RAB Level QoS Parameters" IE is, "X2AP message" IE is when carrying Handover Request message is used by the source (H) eNB1. "E-RAB Level QoS Parameters" IE indicates the same content as "X2AP message" contained in the Handover Request message in IE "E-RAB Level QoS Parameters" IE.
[0084]
　Following the same concept as this, "E-RAB ID" IE shown in FIG. 15B, when the "X2AP message" IE carries Handover Request message may be used by the source (H) eNB1. In this case, "E-RAB ID" IE indicates the same content as "X2AP message" contained in the Handover Request message in IE "E-RAB ID" IE. Furthermore, "E-RAB ID" IE shown in FIG. 15B, when the "X2AP message" IE carries Handover Request Acknowledge message may be used by the target (H) eNB2. In this case, "E-RAB ID" IE indicates the same content as "X2AP message" contained in the Handover Request Acknowledge message in IE "E-RAB ID" IE.
[0085]
　Following the same concept as this, when "DL GTP Tunnel Endpoint" IE and "UL GTP Tunnel Endpoint" IE shown in FIG. 15B, the "X2AP message" IE carrying Handover Request Acknowledge message, the target (H) eNB2 it may also be used. In this case, "DL GTP Tunnel Endpoint" IE and "UL GTP Tunnel Endpoint" IE is, "X2AP message" contained in the Handover Request Acknowledge message in IE "DL GTP Tunnel Endpoint" IE and "UL GTP Tunnel Endpoint" IE and It shows the same content.
[0086]
　Thus, among the plurality of information elements Handover Request message and Handover Request Acknowledge message, U-plane (X2-U) X2AP some information elements X2 GW 3 must reference for relay Message Transfer the following advantages by including the message. That, X2 GW 3 may be transparently forward X2AP Message IE, there is no need to perform reference or decoding X2AP Message IE. If X2 GW3 always referring or decoding X2AP Message IE, X2 to may consume large GW3 processing capability, protocol error occurs in the X2 GW3 protocol version and (H) X2AP protocol version between eNB differ It might be. X2 GW 3, by transparently transferring X2AP Message IE, it is possible to avoid occurrence of these problems.
[0087]
　Incidentally, as shown in FIGS. 15A and 15B, Handover Request message or Handover Request Acknowledge when the information elements and the information elements having the same contents in the message is added to X2AP Message Transfer message, these additional information elements ( for example, "DL Forwarding" IE, at least one of "E-RAB Level QoS Parameters" IE, "E-RAB ID" IE, "DL GTP Tunnel Endpoint" IE, and "UL GTP Tunnel Endpoint" IE) is it may be used as implicit relay request (or relay display). That, X2 GW 3, depending on whether or not include information elements X2AP Message Transfer messages are added may detect the presence or absence of a relay request from the (H) eNB1 or 2. In this case, X2AP Message Transfer message, "Direct Path Unavailability" IE (or other explicit or implicit relay requirements) may be free of.
[0088]

　In the present embodiment, a specific example of a procedure for informing X2 GW 3 of X2-U TNL address (eg, IP address) of the target (H) eNB2. In the first embodiment, X2 example X2-U TNL address GW3 are set to the target (H) eNB2 by OAM, and X2AP Message Transfer message from X2 GW3 with the target (H) eNB2 to X2 GW3 X2 an example in which -U TNL address is notified. Instead of these, improved Enhanced TNL Address Discovery procedure may be used.
[0089]
　Enhanced TNL Address Discovery procedure is defined in Non-Patent Document 1 section 4.6.6.1. The Enhanced TNL Address Discovery procedure, (H) eNB is a TNL address of X2 GW which the (H) eNB is connected S1AP: the included eNB CONFIGURATION TRANSFER message, eNB CONFIGURATION TRANSFER message containing the TNL address of X2 GW to send to the MME. MME obtains the TNL address of target eNB ID and X2 GW included in the eNB CONFIGURATION TRANSFER message, S1AP: transferring TNL address X2 GW to target eNB ID using MME CONFIGURATION TRANSFER message. Thus, the two (H) eNB can recognize the TNL address X2 GW, available indirect X2 via the X2 GW.
[0090]
　However, TNL address X2 GW transferred by existing Enhanced TNL Address Discovery procedure should be noted that it is TNL address for forwarding X2AP signaling message in SCTP connection (i.e., X2-C TNL address) is there. In the present embodiment, TNL address X2 GW for forwarding TNL UDP / IP packets carrying G-PDU (i.e., X2-U TNL address) to forward, Enhanced TNL Address Discovery procedure is changed.
[0091]
　Figure 16 is a sequence diagram showing an example of the (processing 1600) for Enhanced TNL Address Discovery procedure according to the present embodiment. Procedure of Figure 16, except that X2 GW U-plane address (X2-U TNL address) is sent is the same as the existing Enhanced TNL Address Discovery procedure. That is, in block 1601, the source (H) eNB1 is, S1AP: transmits the eNB CONFIGURATION TRANSFER message to MME5. The eNB CONFIGURATION TRANSFER message includes the X2 GW 3 of U-plane address (X2-U TNL address). In block 1602, MME5 is, S1AP: sends the MME CONFIGURATION TRANSFER message to the target (H) eNB2. The MME CONFIGURATION TRANSFER message includes a source (H) eNB1 received from X2 GW 3 of U-plane address (X2-U TNL address).
[0092]
　In block 1603, the target (H) eNB2 adds the received X2 GW 3 of U-plane address (X2-U TNL address) to ACL. In block 1604, the target (H) eNB2 is, S1AP: transmits the eNB CONFIGURATION TRANSFER message to MME5. The eNB CONFIGURATION TRANSFER message is a response to the source (H) eNB1. In block 1605, MME5 is, S1AP: sends the MME CONFIGURATION TRANSFER message to the source (H) eNB1. MME CONFIGURATION TRANSFER message includes a target (H) received information element by eNB CONFIGURATION TRANSFER message from eNB2 (eg, target (H) eNB2 is U-plane addresses X2 GW 3 received from the source (H) eNB1).
[0093]
　17A and 17B show a specific example of the 3GPP TS 36.413 V12.4.0 defined in Section 9.2.3.29 of "X2 TNL Configuration Info" IE changes. "X2 TNL Configuration Info" IE is, S1AP: eNB CONFIGURATION TRANSFER message and S1AP: included in MME CONFIGURATION TRANSFER message. As shown in FIG. 17B, "X2 TNL Configuration Info" IE indicates the TNL address for indirect X2 U-plane endpoint (i.e., X2-U TNL address X2 GW3) "Transport Layer Address" IE it may be extended to include.
[0094]
　Finally, according to embodiments of the above (H) eNB1, (H) eNB2, and X2 configuration example of GW3 will be described. Figure 18 is a block diagram showing a configuration example of (H) eNB1. (H) eNB2 may also have a configuration similar to that of Figure 18. Referring to FIG. 18, (H) eNB1 includes an RF transceiver 1801, a network interface 1803, a processor 1804, and memory 1805. RF transceiver 1801 performs an analog RF signal processing to communicate with the UEs. RF transceiver 1801 may include a plurality of transceivers. RF transceiver 1801 is coupled to antenna 1802 and the processor 1804. RF transceiver 1801 receives the modulated symbol data (or OFDM symbol data) from the processor 1804, generates a transmission RF signal and provides a transmit RF signal to the antenna 1802. Also, RF transceiver 1801 to generate a baseband received signal based on the reception RF signal received by an antenna 1802, and supplies it to the processor 1804.
[0095]
　Network interface 1803 is used to communicate with a network node (eg, MME and S / P-GW). Network interface 1803 may include, for example, a network interface card that complies with the IEEE 802.3 series (NIC).
[0096]
　The processor 1804, performs data plane processing and control plane processing including digital baseband signal processing for wireless communication. For example, in the case of LTE and LTE-Advanced, a digital baseband signal processing by the processor 1804, PDCP layer, RLC layer may include a signal processing of the MAC layer, and the PHY layer. Further, the signal processing by the processor 1804 may include signal processing GTP-U · UDP / IP layer in the X2-U interface and S1-U interface. The control plane processing by the processor 1804, X2AP protocol may include a process of S1-MME protocol and the RRC protocol.
[0097]
　Processor 1804 may include multiple processors. For example, the processor 1804, the processor 1804 performs modem processor that performs digital baseband signal processing (eg, DSP), the signal processing of the GTP-U · UDP / IP layer in the X2-U interface and S1-U interface processor (eg, DSP), and a protocol stack processor for performing control plane processing may include (eg, CPU or MPU).
[0098]
　Memory 1805 is constituted by a combination of volatile and nonvolatile memory. Memory 1805 may include a physically independent plurality of memory devices. Volatile memory may be, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM) or a combination thereof. The non-volatile memory, a mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. Memory 1805 may include a storage that is remotely located from the processor 1804. In this case, the processor 1804 may access the memory 1805 via the I / O interfaces that are not network interface 1803 or illustrated.
[0099]
　Memory 1805 may store software modules (computer program) including instructions and data for processing by that have been (H) eNB1 described in several embodiments above. In some implementations, the processor 1804, the software module that executes from the memory 1805 may be configured to perform processing of which is described in the above embodiment (H) eNB1.

[Claim 1]
　A base station apparatus,
　a memory,
　and at least one processor coupled to said memory,
comprising a
　at least one processor is configured to transmit the first information element in the base station between the gateway,
　the the first information element, explicitly whether to relay processing data packets from the wireless terminal addressed or the wireless terminal a gateway between the base station and relays between the base station device and another base station is required or implicitly shown,
the base station apparatus.
[Claim 2]
　The first information element indicates availability of direct path between the other base station and the base station device explicitly,
the base station apparatus according to claim 1.
[Claim 3]
　Configuration wherein the at least one processor, upon from the other base station or the other base station from the base station apparatus of a handover of the radio terminal to the base station apparatus, to transmit the first information element is,
the base station apparatus according to claim 1 or 2.
[Claim 4]
　Wherein the at least one processor is configured to include the first information element to transfer messages sent to the base station between the gateway to carry the other handover request message or a handover request acknowledge message to the base station are,
the base station apparatus according to claim 3.
[Claim 5]
　The first information element is to indicate implicitly that the relay process is required, the handover request message or said second information being included in the handover request acknowledge message is carried by the transfer message shows the same content as the element,
the base station apparatus according to claim 4.
[Claim 6]
　Wherein the at least one processor is configured to include the handover request message or a third information elements of the same content as the second information element that is included in the handover request acknowledgment message carried by the transfer message to the forwarded message is,
the base station apparatus according to claim 4.
[Claim 7]
　The second information element is an information element indicating the necessity of forwarding the data packet, the information element indicating an identifier of the set bearer for said wireless terminal, and of Quality of Service (QoS) parameters of the bearer at least one containing, in the information element indicating
the base station apparatus according to claim 5 or 6.
[8.]
　Wherein the at least one processor, the transfer and the information element indicating the type of inter-base station signaling message carried by the message is configured to include in the transfer message,
the base according to any one of claims 4-7 office equipment.
[Claim 9]
　Wherein the at least one processor, said for transmission or reception of data packets, is configured to determine whether to use the relay processing by the gateway between the base station,
　when said relay processing is not available, the data packet, the said base station apparatus is forwarded using the direct path between the other base station,
the base station apparatus according to any one of claims 1-8.
[Claim 10]
　Wherein the at least one processor, in generating the first information element, the base station between the gateway is configured to consider whether it has the capability of said relay process,
of claims 1 to 9, the base station apparatus as claimed in any one.
[Claim 11]
　Wherein the at least one processor, said has a fourth information element indicating the ability of the relay process is configured to receive from the gateway between the base station,
the base station apparatus according to any one of claims 1 to 10 .
[Claim 12]
　Wherein the at least one processor, in the procedure for registering the base station apparatus to the base station between the gateway is configured to receive the fourth information elements,
the base station apparatus according to claim 11.
[Claim 13]
　Wherein the at least one processor, in generating the first information element, wherein being configured to consider the state of the direct path between the base station apparatus and the other base stations,
according to claim 1 to 12 the base station apparatus according to any one of.
[Claim 14]
　Wherein the state of the direct path is, availability of the direct path, the direct path of the throughput, and includes at least one of the load of the direct path,
the base station apparatus according to claim 13.
[Claim 15]
　Wherein the at least one processor, in generating the first information element, the transport layer address of the base station device is configured to consider whether there is a need to hide from the other base station are,
the base station apparatus according to any one of claims 1 to 14.
[Claim 16]
　Wherein the at least one processor, in generating the first information element, wherein being configured to consider the type of other base stations,
base station according to any one of claims 1 to 15 apparatus.
[Claim 17]
　A between the base station gateway device,
　a memory,
　and at least one processor coupled to said memory,
comprising a
　said at least one processor, a first information element first base station and second base is configured to receive from at least one station,
　the first information element, the wireless terminal addressed or said second base and the first base station the data packet by the base station between the gateway device from the wireless terminal explicitly or implicitly indicate, whether the relay processing is required to be relayed between the stations
the base station between the gateway device.
[Claim 18]
　A method performed by a base station apparatus,
　comprising transmitting a first information element in the base station between the gateway,
　the first information element, the base data packet from the wireless terminal addressed or the wireless terminal interoffice gateways shown explicitly or implicitly whether required relay process of relaying between the base station device and another base station,
the method.
[Claim 19]
　A method performed by a base station between the gateway apparatus
　comprises receiving from at least one of the first information element first base station and second base station,
　the first information element, the wireless terminal explicitly or implicitly whether required relay process of relaying between addressed or the second base station and the first base station the data packet by the base station between the gateway apparatus from said wireless terminal to show,
way.
[Claim 20]
　The method performed by the base station apparatus A non-transitory computer readable medium storing a program for causing a computer,
　the method comprises transmitting first information element in the base station between the gateway,
　wherein the first information element, whether or not the relay process of the data packet from the wireless terminal addressed or the wireless terminal a gateway between the base station and relays between the base station device and another base station is required explicitly or implicitly indicate,
non-transitory computer readable media.
[Claim 21]
　The non-transitory computer readable medium storing a program for causing the method performed by the base station between the gateway device to a computer,
　the method comprising the first information element first base station and the second comprises receiving from at least one base station,
　the first information element, the wireless terminal addressed or said between said base station a data packet from the wireless terminal a gateway apparatus the first base station and the second by whether or not the relay processing for relaying between the base stations are needed shown explicitly or implicitly,
non-transitory computer readable media.