Technical field
[0001]
　The disclosure herein relates to a Self-Organizing Network (SON) technology for self-configuring radio access network (Radio Access Network (RAN)) (Self-configuration) or self-optimizing (Self-optimization), especially Automatic Neighbour Relation (ANR) feature on.
Background technique
[0002]
　Chapter 22 of Non-Patent Document 1, for the Self-Organizing Network (SON) technology for self-configuration of Evolved Universal Terrestrial Radio Access Network (E-UTRAN) (Self-configuration) and self-optimizing (Self-optimization) It prescribes. E-UTRAN is a radio access network of Long Term Evolution (LTE). SON technology, which is defined in Chapter 22 of Non-Patent Document 1, the dynamic configuration of the S1-MME interface and the X2 interface (Dynamic configuration), Automatic Neighbour Relation (ANR) feature, Mobility Load Balancing, Mobility Robustness Optimization (MRO) and the like. S 1-the MME interface (S1-MME link) is the communication interface between the evolved NodeB (eNB) and a core network (Evolved Packet Core (EPC)) is disposed within the Mobility Management Entity (MME). X2 interface (X2 link) is the communication interface between the eNB. eNB is the base station of the E-UTRAN / Long Term Evolution (LTE). MME is a control entity which is arranged in the core network (Evolved Packet Core (EPC)), mobility management User Equipment (UE) (eg location registration), and bearer management (eg bearer establishment, bearer configuration change, bearer release) is performed, such as. UE is a E-UTRAN / LTE radio terminals (mobile terminals).
[0003]
　ANR function, is one of the important features of SON. The purpose of the ANR function is to release the operator from the burden of managing the adjacent cell relationship (Neighbor Relations (NRs)) manually. Figure 1 shows a plurality of elements included in the ANR functions described in Non-Patent Document 1. Figure 2 shows a specific example of the adjacency table described in Non-Patent Document 1 (Neighbor Relation Table (NRT)).
[0004]
　As shown in FIG. 1, ANR function is disposed evolved NodeB (eNB), manages a conceptual (conceptual) NRT. Neighbour Detection Function is to discover a new adjacent cell, add a corresponding NRs to NRT in this. Neighbour Removal Function deletes unnecessary NRs from NRT.
[0005]
　NRT encompasses the entry of all of the adjacent cell relationship of the cell eNB controls (NRs). NR in the NRT context is defined as the relationship between cell-to-cell in one direction (unidirectional) from the source cell to the target cell. As shown in FIG. 2, for each NR, NRT includes identifying a target cell Target Cell Identifier (TCI). If the target cell is a E-UTRAN cell, TCI corresponds to E-UTRAN the Cell Global Identifier of target cell (ECGI) and Physical Cell Identity (PCI). ECGI is composed of three bytes Public Land Mobile Network Identity (PLMN ID) and 28-bit E-UTRAN Cell Identifier (ECI), it is used the E-UTRAN cell to uniquely identify globally. PLMN IDs is a unique identifier of the PLMN, ECI is the unique identifier of the E-UTRAN cells in a particular PLMN. In contrast, PCI is a number from 0 to 503, to distinguish immediately To become of the adjacent cell to cell. Within PLMN, the PCI of types 504 (0 to 503) are repeatedly used. That, PCI is not possible to specify an intra-PLMN or globally to the cell.
[0006]
　Furthermore, as shown in FIG. 2, entries for NR held in NRT may have multiple attributes. The plurality of attributes includes three attributes that are controlled by the Operation and Maintenance (OAM) system (No Remove flag, No HO flag, and No X2 flag) a. No in The Remove flag indicates whether eNB can delete the corresponding NR. No HO flag indicates whether or not the eNB can use the corresponding NR in the handover purpose. No in X2 flag indicates whether an X2 interface to initiate a procedure with the eNB which controls the target cell (X2 link) can be used.
[0007]
　Intra-LTE and the case of Intra-frequency, ANR function works as follows. ANR function relies on the cell to broadcast a unique identifier (ie ECGI) in their global (cells). The serving eNB with ANR function instructs the measurement of the normal neighboring cells to each UE. UE sends a normal measurement report to the serving eNB (measurement report). The normal measurement report, including PCI neighboring cells do not include ECGI of neighboring cells.
[0008]
　If the measurement report from the UE indicates a new PCI not captured in the serving eNB, the serving eNB may use the newly discovered PCI as a parameter, instructs the UE to perform a separate report (dedicated reporting) to. The UE, if it can detect a new cell corresponding to the PCI newly discovered, ECGI, the Tracking Area Code (TAC), system information including all available PLMN ID (s) (System information) reading, which are reported to the serving eNB in ​​a separate report. TAC indicates the tracking area in which cells of the eNB belongs. TAC is composed of 16 bits, a unique identifier within the PLMN,
[0009]
　The serving eNB may use the PCI and ECGI reported by the UE, and decides to add NR to the newly discovered cell from the source cell to the NRT. The serving eNB in ​​order to find a transport layer address of an eNB that controls the newly discovered cell (lookup), may be used PCI and ECGI reported by the UE. Further, the serving eNB in ​​order to set up the X2 interface (X2 link) the eNB controlling the newly discovered cell, it may be used those PCI and ECGI.
CITATION
Non-Patent Document
[0010]
非特許文献1 : 3GPP TS 36.300 V9.10.0 (2012-12), “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 9)”, 2012年12月
非特許文献2 : 3GPP TS 36.423 V9.6.0 (2011-03), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access Network (E-UTRAN); X2 application protocol (X2AP) (Release 9)”, 2011年3月
Summary of the invention
Problems that the Invention is to Solve
[0011]
　As understood from the above description, the ANR function, addition or deletion of NRs cell is performed based on the measurement report to the eNB for controlling the cell from the UE. In other words, that you run the ANR feature detection to trigger the handover disorders such as Too Late Handover and Handover to Wrong Cell is not assumed. Describe the definition of Too Late Handover and Handover to Wrong Cell in this specification.
[0012]
　(1) Too Late first type of Handover is radio link failure UE during a handover procedure from a source cell to a target cell with the cleavage of the Radio Resource Control (RRC) connection in the source cell (Radio Link Failure ( RLF)) experienced a situation trying to Radio Resource Control (RRC) re-establishment of the connection (re-establishment) for subsequent target cell.
[0013]
　(2) Too Late the second type of Handover is, UE will experience the RLF in the source cell before the start of the handover, by then to try to re-establish the RRC connection for different other cells of the source cell situation is there.
[0014]
　(3) Handover to Wrong first type of Cell is to experience the RLF in a UE is the target cell immediately after or the handover of completion during the handover procedure from a source cell to the target cell, and then to the source cell and the target cell than either the situation to try to re-establish the RRC connection for different other cells.
[0015]
　(4) Handover to Wrong second type of Cell is to experience the RLF in a UE is the source cell during the handover procedure from a source cell to the target cell, either with different other cells also subsequent to the source cell and the target cell it is a situation to try to re-establish the RRC connection to.
[0016]
　Defining handover failure described above, not intended deterministic, sometimes different definition is made to the above definition. For example, the second type of Handover to Wrong Cell may be included in the second type of Too Late Handover. This is because, the second type of Handover to Wrong Cell is, UE is in that attempt to re-establish the RRC connection to other cells not handover is started after experiencing the RLF in the source cell, the of Too Late Handover This is because in common with the second type.
[0017]
　In the second type of the aforementioned Too Late Handover, RLF INDICATION message is sent in the X2 link to eNB controlling the source cell from the eNB controlling the other cell. The RLF INDICATION message, the UE failure cell (that is, the source cell) who have experienced the RLF including the ECGI of and PCI, re-establishment cell the UE has attempted to re-establish the RRC connection (that is, other cells). In the second type of the above-mentioned Handover to Wrong Cell, the same RLF INDICATION message to the eNB to control the source cell from the eNB to control the other cell is sent.
[0018]
　In addition, in the first of the type described above of Handover to Wrong Cell, to the eNB to control the target cell from the eNB to control the other cell RLF INDICATION message is sent, further to control the source cell from the eNB to control the target cell HANDOVER REPORT message is sent to the eNB. The RLF INDICATION message indicates the PCI of the target cell as a failure cell, the ECGI of other cells as a re-establishment cell. This HANDOVER REPORT message, the handover failure type (in this case, Handover to Wrong Cell) of the shows of the source cell ECGI, ECGI of the target cell as a failure cell, and the ECGI of other cells as a re-establishment cell. Transmission condition of RLF INDICATION message and HANDOVER REPORT message are included in the 22.4.2 Section et al. RLF INDICATION message and HANDOVER REPORT message details of contexts, are described in Chapter 9.1.2.18 Section and second 9.1.2.19 Section Non-Patent Document 2.
[0019]
　To reduce the handover failure, in response to receiving the RLF INDICATION message or HANDOVER REPORT message, technology base station of the source cell to adjust the handover parameters are referred to as handover optimization or Mobility Robustness Optimization (MRO). Handover parameters, for example, Cell Individual acts on the radio quality of the neighboring cell Offset (CIO), Qoffset acting on the radio quality of the neighboring cell, a3-offset that acts on the radio quality of the source cell, control the time to initiate a handover Time to Trigger for including the (TTT).
[0020]
　In the first and second type of the second type and Handover to Wrong Cell of Too Late Handover as described above, the source cell NRs (NRT), in addition to the re-establishment of the RRC connection by the UE is attempted it should be noted that there may not contain an entry for the cell (re-establishment cell). However, the reception of the RLF INDICATION message or HANDOVER REPORT message, in other words to trigger the detection of the handover failure, that you run the ANR function is not assumed. Thus, eNB of the source cell, not be able to add a new NR from the source cell to another cell (re-establishment cell) to the source cell NRs (NRT). Accordingly, updating of NRs of the source cell (i.e., addition of a new NR) it may take time.
[0021]
　Furthermore, MRO is generally performed for NRs of the source cell held in the NRT. This is because neighbor cell list notified from the eNB to the UE (Neighbour Cell List (NCL)) is because it is the same as or a subset of the NRs contained in NRT. Neighbor cells included in NCL, in one example, is the subject of measurement report by the UE in the RRC_CONNECTED state, and may be specified in the handover target cell of the UE. Accordingly, cells not included in NRs of the source cell are not subject to the optimization of the handover parameters. Therefore, it can not run ANR in response to the detection of the handover failure, there is a risk that delay the improvement of the handover by the MRO.
[0022]
　Thus, one object to be achieved embodiments disclosed herein may contribute controller, the base station apparatus to update the neighbor cell relations (NRs) in response to the detection of the handover failure, how is to provide, and program. Incidentally, this objective should embodiments disclosed herein may be noted that only one of a plurality of object to be achieved. Other objects or problems and novel features will become apparent from the description, or the accompanying drawings.
Means for Solving the Problems
[0023]
　In one embodiment, the controller includes memory and a processor. The memory may store an adjacency table containing a plurality of entries indicating neighbor cell relationship to each neighbor cell from the source cell. Wherein the processor is configured to automatically update the adjacency table. Wherein the processor is further to the source cell and different other cells than either of the target cell after the wireless terminal has experienced a fault involving cleavage of a radio link connection in the handover target cell from the source cell or the source cell in response to receiving the first message that is issued when attempting to re-establish the radio link connection for said new entry indicating neighbor cell relationship to the other cells from the source cell It is configured to be added to the adjacency table.
[0024]
　In one embodiment, the base station apparatus, including a communication interface and processor. The communication interface is utilized between the base station apparatus and another base station, or to communicate between the base station apparatus and a core network device. Wherein the processor is configured to control the establishment of a radio link connection for communication with the base station apparatus and the wireless terminal. Wherein the processor is further said after said wireless terminal has experienced a fault involving cleavage of a radio link connection in the second cell as a first handover target cell from the first cell or the first cell the when trying to reestablish the radio link connection to one of the cells and any and third cells having different also of the second cell, the communication interface to the first base station controlling the first cell It is configured to transmit a first message through. Said first message, at least including the Physical Cell Identifier (PCI) of the third cell.
[0025]
　In one embodiment, the wireless terminal includes a wireless transceiver and a processor. Wherein the processor is configured to control the establishment of a radio link connection for communication via the radio transceiver among the radio terminal and the base station. Wherein the processor is further
after experiencing a disorder involving cleavage of the radio link connection in the target cell during or the handover after completed handover to the target cell from (a) the source cell, the radio link connection It sends a re-establishment request message for requesting the re-establishment to any different other cells also of the source cell and the target cell,
a rejection message indicating that it is rejected (b) the re-establishment request message in response to receiving from the base station controlling the other cell, running between the establishment procedures for a new radio link connection base station controlling the other cell,
the (c) the establishment procedure or following the said establishment procedure between, sending a first message at least including Physical cell Identifier (PCI) of the source cell to the base station controlling the other cell,
executing a control procedure comprising the It is configured to.
[0026]
　In one embodiment, a method of updating adjacency table, any wireless terminal of the source cell and the target cell after experiencing a disorder involving cleavage of a radio link connection in the target cell for handover from the source cell or the source cell be responsive to receiving a first message that is issued when attempting to re-establish the radio link connection to different other cells and the neighbor cell relationship from the source cell to the other cells a new entry indicating, comprising adding to the adjacency table of the base station controlling the source cell.
[0027]
　In one embodiment, a control method performed by the base station is accompanied by cleavage of the radio link connection radio terminal in the second cell as a first handover target cell from the first cell or the first cell If the relative said first cell and all the third cell which varies in the second cell after experiencing a fault attempts to reestablish the radio link connection, the controls said first cell 1 the base station includes transmitting the first message. Said first message, at least including the Physical Cell Identifier (PCI) of the third cell.
[0028]
　In one embodiment, a control method performed by the wireless terminal
involves the disconnection of the radio link connection in said wireless terminal said target cell during or the handover after completed handover to the target cell from (a) a source cell after experiencing the fault, sending a re-establishment request message for requesting the re-establishment of the radio link connection to any different other cells also of the source cell and the target cell,
(b) the re-establishment a rejection message indicating that the request message is rejected in response to receiving from the base station controlling the other cell, the establishment procedure of the new radio link connection with the base station controlling the other cell that run between, and
(c) to follow or the establishment procedure between the established procedure, E-UTRAN cell Global Identifier of the source cell (ECGI), Physical cell Identifier ( PCI), tracking Area Code ( TAC), and EUTRA Absolute Radio Frequency Channel Number (EARFCN a first message comprising at least one of) sending to the base station controlling the other cell,
including.
[0029]
　In one embodiment, the program includes the case loaded into the computer, instructions for performing any of the methods described above to a computer (software code).
Effect of the invention
[0030]
　According to the above-described embodiment, it is possible to provide contributes control apparatus to update a neighbor cell relations (NRs) in response to the detection of the handover failure, the base station apparatus, method, and program.
Brief description of the drawings
[0031]
Is a diagram showing a plurality of elements included in FIG. 1] Automatic Neighbour Relation (ANR) function.
FIG. 2 is a diagram showing a specific example of the adjacency table (Neighbor Relation Table (NRT)) .
3 is a diagram illustrating a configuration example of a wireless communication system according to the first embodiment.
4 is a sequence diagram showing an example of a control procedure according to the first embodiment.
5 is a diagram showing a specific example of an improved RLF INDICATION message according to the first embodiment.
6 is a diagram showing a specific example of the adjacency table (NRT) according to the first embodiment.
7 is a flowchart showing an example of a control method performed by the eNB according to the first embodiment.
8 is a diagram illustrating a configuration example of an eNB according to the first embodiment.
9 is a diagram showing another configuration example of the eNB according to the first embodiment.
10 is a diagram showing another configuration example of the eNB according to the first embodiment.
11 is a flowchart showing an example of a control method performed by the eNB according to the second embodiment.
12 is a sequence diagram showing an example of a control procedure according to the second embodiment.
13 is a sequence diagram showing an example of a control procedure according to a third embodiment.
14 is a sequence diagram showing an example of a control procedure according to a third embodiment.
15 is a diagram showing another configuration example of the radio communication system according to the fourth embodiment.
[FIG. 16A] is a sequence diagram showing an example of a control procedure according to the fourth embodiment.
[FIG 16 B] is a sequence diagram showing an example of a control procedure according to the fourth embodiment.
[FIG. 17A] is a sequence diagram showing an example of a control procedure according to the fifth embodiment.
[FIG. 17B] is a sequence diagram showing an example of a control procedure according to the fifth embodiment.
FIG. 18 is a diagram showing a specific example of an improved HANDOVER REPORT message according to the fifth embodiment.
[FIG. 19A] is a sequence diagram showing an example of a control procedure according to a sixth embodiment.
[FIG. 19B] is a sequence diagram showing an example of a control procedure according to a sixth embodiment.
[FIG. 19C] is a sequence diagram showing an example of a control procedure according to a sixth embodiment.
FIG. 20 is a diagram illustrating a configuration example of a UE according to a sixth embodiment.
DESCRIPTION OF THE INVENTION
[0032]
　Hereinafter, specific embodiments will be described in detail with reference to the accompanying 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.
[0033]
　A plurality of embodiments described below can can either be carried out independently, also be implemented in appropriate combination. These more embodiments, have different novel features with each other. Accordingly, the plurality of embodiments, contributes to solving different purposes or challenge each other, which contributes to achieve different effects from each other.
[0034]

　FIG. 3 shows a configuration example of a wireless communication system according to this embodiment. The wireless communication system provides communication services, both for example, voice communication or packet data communication or these. Referring to FIG. 3, the radio communication system includes base stations 1A and 1B, and the wireless terminal 2. In the present embodiment, the wireless communication system is described as a LTE system or LTE-Advanced system. That is, each of the base stations 1A and 1B corresponds to the eNB, the radio terminal 2 corresponds to the UE.
[0035]
　eNB1A and 1B, to control the cell 10A and 10B, respectively. eNB1A and 1B, the communication interface between base stations, ie to establish an X2 interface (X2 link) 51, may communicate with each other via the X2 interface 51.
[0036]
　eNB1A has improved ANR function. eNB1B may also have the same ANR function and eNB1A. The following description with reference to FIG. 4 for improved ANR function possessed eNB1A. Incidentally, FIG. 4, assume a second type of Too Late Handover as described above, in the direction from the cell 10A to the cell 10B shows a case in which UE2 moves.
[0037]
　First, in step S101, UE2 has established an RRC connection in a cell 10A of eNB1A. In other words, UE2 is RRC_CONNECTED state in a cell 10A.
[0038]
　Here, to clarify the definition of the RRC connection and radio link connection to be used in the present specification. RRC connection is an example of a radio link connection. RRC connection is used to send and receive control messages regarding RRC protocol between the UE and the eNB. RRC connection includes a UE-specific control messages (ie, RRC message and Non-Access Stratum (NAS) message) signaling radio bearer for transmitting and receiving (Signalling Radio Bearer (SRB)).
[0039]
　Establishment of the RRC connection, at least, SRB for transmitting and receiving UE-specific control messages (ie, Signalling Radio Bearer 1 (SRB1)) means a state in which has been established. RRC_CONNECTED means a state of the UE RRC connection is established. eNB holds information (UE Context) related to the UE RRC_CONNECTED. The position of the UE of RRC_CONNECTED are grasped on a cell-by-cell basis (or eNB units) in the core network (EPC). RRC_CONNECTED of the UE can generally be carried out unicast data transfer with eNB. On the other hand, RRC_IDLE means a state of the UE RRC connection has been released. eNB has no information (UE Context) related to the UE RRC_IDLE. The position of the UE of RRC_IDLE are grasped in the tracking area units in the EPC. The EPC, can be reached by paging the UE of RRC_IDLE. Further, UE of RRC_IDLE can not perform unicast data transfer with the eNB. Therefore, UE in RRC_IDLE shall transition to RRC_CONNECTED in order to perform unicast data transfer.
[0040]
　Referring back to FIG 4. In step S 102, UE 2 moves towards the cell 10B. However, neighbor cell relation of cells 10A having the eNB1A (NRs) or NRT does not contain an entry for the cell 10B. Therefore, UE2 of handover from cell 10A of eNB1A to cell 10B of eNB1B is not started. For this reason, UE2 is, to experience the RLF with the cutting of the RRC connection in the cell 10A.
[0041]
　In step S 103, UE 2 detects the cell 10B, attempting to re-establishment of RRC connection (re-establishment) to the cell 10B. Specifically, UE2 sends the RRC Connection Re-establishment Request message to eNB1B of cell 10B. Incidentally, are not shown in the random access procedure including 4, the transmission of the Physical Random Access Channel (PRACH) preamble is performed prior to sending the RRC Connection Re-establishment Request message.
[0042]
　RRC Re-establishment Request message sent in step S103 shows "other failure" as Reestablishment the Cause. "Other failure" corresponds to the "Radio Link Failure" as an example. Further, RRC Connection Re-establishment Request message, Physical Cell Identity of the cell 10A (PCI), Cell granted to UE2 in the cell 10A Radio Network Temporary Identifier (C-RNTI), and shortMAC-the I for security algorithms including. PCI, as already mentioned, a number from 0 to 503, an identifier for distinguishing cell and the adjacent cell, is used repeatedly in the frequency. C-RNTI is a temporary identifier unique to the cell, is used to perform a separate transmission to the UE. shortMAC-it is used in order to identify and and authenticate the UE in RRC Connection Re-establishment. shortMAC-the I is 16 least significant bits (16 Least Significant among the security configuration of a cell where the UE was connected immediately before (security configuration) computed Message Authentication Code for data Integrity using (MAC-I) corresponding to the bits).
[0043]
　RRC CONNECTION RE-ESTABLISHMENT procedure initiated by the RRC Connection Re-establishment Request message is performed for the purpose of re-establishment of the RRC connection is disconnected immediately before. Re-establishment of the RRC connection, including the resumption of SRB1 (resumption) and re-activation of the security algorithm (re-activation). However, RRC CONNECTION RE-ESTABLISHMENT procedure, only be successful if the eNB which has received the RRC Connection Re-establishment Request message is to hold a valid UE context.
[0044]
　In the Figure 4 case, ENB1B does not have a valid UE context of UE 2. Because handover from the cell 10A to the cell 10B is not started, therefore, ENB1B is because it does not receive a valid UE context UE2 from eNB1A. Therefore, in step S104, eNB1B transmits the RRC Connection Re-establishment reject message. UE2 returns to RRC_IDLE in response to RRC Connection Re-establishment Reject message. Although not shown in FIG. 4, after step S 103, UE 2 in order to establish a new RRC connection may initiate a RRC CONNECTION ESTABLISHMENT procedure includes sending the RRC Connection Request message to eNB1B .
[0045]
　eNB1A corresponds to the failure cell which UE2 experienced the RLF. On the other hand, eNB1B corresponds to the re-establishment cell that UE2 tried to RRC Connection Re-establishment. Accordingly, in step S105, eNB1B through the X2 interface 51, and transmits the RLF INDICATION message to eNB1A. The RLF INDICATION message indicates that an attempt to reestablish of the RRC connection to the cell 10B after the UE2 has experienced RLF with cleavage of the RRC connection in a cell 10A.
[0046]
　Furthermore, RLF INDICATION message transmitted at step S105 is modified to include additional information elements (Information Elements (IEs)). Specifically, the improved RLF INDICATION message includes a PCI of the re-establishment cell (ie, cell 10B). The improved RLF INDICATION message may further comprise a TAC or EUTRA Absolute Radio Frequency Channel Number (EARFCN) or both of these re-establishment cell (cell 10B). EARFCN is a number from 0 to 65535, associated with one-to-one with the use of carrier wave frequency (carrier frequency) in the LTE. PCI of the re-establishment cell (cell 10B), TAC, and EARFCN are naturally grasped in eNB1B to issue and RLF INDICATION message to control the re-establishment cell (cell 10B).
[0047]
　5 shows a specific example of an improved RLF INDICATION message. In the example of FIG. 5 of 5, RLF INDICATION message improvements include PCI of re-establishment cell (cell 10B), TAC, and the information element indicating EARFCN a (IE). In the example of FIG. 5 of 5, presence of these additional information elements (IE) is a "Optional (O)", other values, i.e. met "Mandatory (M)" or "Conditional (C)" it may be.
[0048]
　Referring back to FIG 4. In step S106, eNB1A is based on receipt of RLF INDICATION message from ENB1B, it detects the Too Late Handover. eNB1A is stored in a memory (not shown) the detected Too Late Handover as history information of the handover failure.
[0049]
　In step S107, eNB1A responds to the UE2 receives the RLF INDICATION message indicating that tries to reestablish the relevant RRC connection to the cell 10B after experiencing the RLF with the cutting of the RRC connection in a cell 10A on, run the ANR, which includes updating adjacent cell relationship of cell 10A the (NRs). In other words, ENB1A say in response to detection of Too Late Handover to UE2 of RLF in without cells 10A to outward handover from cell 10A is started corresponds to that occurring, updates the NRs cell 10A it is also possible. Specifically, eNB1A adds new neighbour relation towards the cell 10B a (NR) in the NRT of cell 10A from the cell 10A.
[0050]
　6 shows an example of NRT cell 10A after being updated by the ANR operation in step S107. NRT40 shown in FIG. 6 includes a new entry 41 relates NR directed from the cell 10A to the cell 10B. Here, TCI cell 10B which are included in entry 41 (ie, ECGI and PCI), is noted that obtained from information elements included in the RLF INDICATION message to an improved received from eNB1B (IEs) it should. ECGI of the cell 10B as Re-establishment cell is also included in the existing RLF INDICATION message. However, PCI's cell 10B as Re-establishment cell, as shown in the example of FIG. 5, a novel information element improved RLF INDICATION message according to the present embodiment has (IE). In addition, as shown in FIG. 6, entry 41 may include a EARFCN and TAC of cell 10B in the NR. These EARFCN and TAC also, as shown in the example of FIG. 5 can be obtained from the novel information elements improved RLF INDICATION message according to the present embodiment has (IE).
[0051]
　Referring back to FIG 4. The order of steps S106 and step S107 described above is not particularly limited. Processing performed in steps S107 to step S106 may be executed independently of each other. ANR processing in step S107 may be performed before the processing in step S106, it may be performed in parallel with this.
[0052]
　In step S108, eNB1A, using the history information of the stored handover failure, it executes the MRO for the cell 10A, including the optimization of the handover parameters. Prior to this MRO, NR towards the cell 10B is added in step S107 from the cell 10A. Therefore, eNB1A is, the handover parameters related to handover from cell 10A to cell 10B may be the subject of the MRO.
[0053]
　Incidentally, the sequence of FIG. 4 is only an example and may be appropriately modified. For example, re-establishment cell (ie, cell 10B) PCI of, TAC, EARFCN etc. may be transmitted using different X2 application protocol (X2AP) message to the RLF INDICATION message. eNB1A is, for example, existing in the same (that is, not including PCI of the re-establishment cell, TAC, the EARFCN) RLF the INDICATION message received from the eNB1B, the RLF INDICATION message to be included the re-establishment cell (cell 10B) It determines that the NR corresponding to the ECGI is not included in the NRT cell 10A, and may send a X2AP message for requesting transmission of PCI, etc. re-establishment cell (cell 10B) to eNB1B . eNB1B may send a X2AP message indicating the PCI or the like in response re-establishment cell (cell 10B) to a request from ENB1A to eNB1A. Alternatively, ENB1A can transmit may request a PCI, etc. re-establishment cell (cell 10B) to the UE located in the cell 10A. Some other modification of, are described in the embodiment, which will be described later.
[0054]
　Figure 7 is a flowchart illustrating an example of a control procedure performed by eNB1A. In the step S11, eNB1A receives the RLF INDICATION message from eNB1B through the X2 interface 51. In the step S12, eNB1A is, failure cell (ie, cell 10A) NRs of the re-establishment cell (ie, cell 10B) to check whether or not the inclusion of the NR with. Specifically, ENB1A the entry indicating the ECGI of the RLF INDICATION message contained the re-establishment cell (cell 10B), it may be confirmed whether or not included in the NRT of failure The cell (cell 10A) . If NRs of failure The cell (cell 10A) does not include NR a re-establishment cell (cell 10B) (NO at step S12), eNB1A is, NRs cell 10A and NR directed from the cell 10A to the cell 10B ( to run the ANR operations including adding to NRT).

The scope of the claims
[Claim 1]
　A memory capable of storing adjacency table containing a plurality of entries indicating neighbor cell relationship to each neighbor cell from the source cell,
　and a processor configured to automatically update the adjacency table
includes a,
　the processor , the wireless to any different other cells also of the source cell and the target cell after the wireless terminal has experienced a fault involving cleavage of a radio link connection in the handover target cell from the source cell or the source cell in response to the first message that is issued when an attempt to reestablish the link connection to receiving, a new entry indicating neighbor cell relationship to the other cells from the source cell to the neighbor relation table add,
control device.
[Claim 2]
　The first message via the communication link established between the base station is received at the base station controlling the source cell, the control device according to claim 1.
[Claim 3]
　Wherein the first message is a RLF INDICATION message transmitted from the base station controlling the other cell to the base station controlling the source cell,
the control device according to claim 1 or 2.
[Claim 4]
　The RLF INDICATION message, experiences radio link failure (Radio Link Failure) the radio terminal without outward handover is started in the source cell from the source cell, and the radio terminal is the other cells It is transmitted when trying to reestablish the radio link connection for,
control device according to claim 3.
[Claim 5]
　The RLF INDICATION message, the wireless terminal during a handover to the target cell from the source cell experiencing a radio link failure (Radio Link Failure) or handover failure (Handover failure) in the source cell, and the radio terminal There is transmitted when trying to reestablish the radio link connection to said another cell,
the control device according to claim 3.
[6.]
　Said first message, said wireless terminal during the or the handover after handover from the source cell to said target cell is completed experiencing a radio link failure (Radio Link Failure) in the target cell, and the radio If the terminal attempts to re-establish the radio link connection to said another cell, a HANDOVER REPORT message sent to the base station controlling the source cell from the base station controlling the target cell,
according control apparatus according to claim 1 or 2.
[7.]
　The first message arrives at the controller via the core network device, the control device according to claim 1.
[8.]
　The RLF INDICATION message, the other at least comprising the Physical Cell Identifier (PCI) of the cell,
the control device according to any one of claims 3-5.
[9.]
　The HANDOVER REPORT message, at least including the Physical Cell Identifier (PCI) of the other cell,
the control device according to claim 6.
[10.]
　Wherein the processor in the procedure of establishing a first information element that is included in the first message, the communication link between the base station controlling the other cell and the base station controlling the source cell on the basis of the second information element received from the base station which manages the other cells, it generates the new entry,
the control device according to any one of claims 1 to 7.
[11.]
　The processor includes a first information element that is included in the first message, received via a communication link between the base station controlling the other cell and the base station controlling the source cell on the basis of the second information element that is included in a message indicating an update of the configuration of the base station which manages the other cells, it generates the new entry,
any one of claims 1 to 7, control device according to.
[12.]
　The first information element includes the other cells of the E-UTRAN Cell Global Identifier (ECGI ),
　the second information element, comprising said other cells in the Physical Cell Identifier (PCI),
according to claim 10 or control device according to 11.
[13.]
　The communication link is the X2 link, control device according to any one of claims 10-12.
[14.]
　The radio link connection is a Radio Resource Control (RRC) connection,
the control device according to any one of claims 1 to 13.
[15.]
　Wherein the processor is further to optimize the handover parameters related handover from the source cell to the other cell, the control device according to any one of claims 1 to 14.
[16.]
　A base station apparatus,
　between the base station apparatus and another base station, or a communications interface for communicating between the base station apparatus and a core network apparatus,
　and from the base station apparatus and the wireless terminal a processor configured to control the establishment of a radio link connection for communicating
with a,
　wherein the processor, the wireless terminal as a first handover target cell from the first cell or the first cell in the second cell of attempts to re-establish one and the radio link connection also for different third cell of the first cell and the second cell after experiencing a disorder involving cleavage of the radio link connection If the via the communication interface a first cell to the first base station controlling transmit a first message,
　the first message, the first three cell Physical cell Identifier (PCI) at least it includes, the
base station equipment.
[17.]
　Wherein the first message is a RLF INDICATION message,
　the base station apparatus controls the Ki third cell,
the base station apparatus according to claim 16.
[18.]
　The RLF INDICATION message,
experiences radio link failure (Radio Link Failure) in (a) the wireless terminal is the first cell without outward handover is started from the first cell, and the radio If the terminal attempts to re-establish the radio link connection to the third cell,
(b) the radio link failure in the wireless terminal is the first cell during a first handover (radio link failure ) or experiencing a handover failure (handover failure the), and wherein when the wireless terminal attempts to re-establish the radio link connection to the third cell, or
(c) the first from the fourth cell experienced radio link failure (radio link failure) in the wireless terminal is the first cell during the or the second handover after a second handover to the cell is completed, and the radio terminal is the third the relative cell when attempting to re-establish a radio link connection,
the transmitted from the base station apparatus to the first base station,
the base station apparatus according to claim 17.
[19.]
　Wherein the first message is a HANDOVER REPORT message,
　the base station apparatus controls the second cell,
　the HANDOVER REPORT message, or the first handover after the first handover is completed when the wireless terminal experiences a radio link failure (radio link failure) in the second cell, and the wireless terminal attempts to re-establish the radio link connection to the third cell during, transmitted from the base station apparatus to the first base station,
the base station apparatus according to claim 16.
[20.]
　The processor, in response to at least include RLF INDICATION message Physical Cell Identifier (PCI) of the third cell exhibits the occurrence of the failure has been received from the base station controlling the third cell, transmitting the HANDOVER REPORT message to the first base station,
the base station apparatus according to claim 19.
[21.]
　Said first message, triggers the updating of adjacency tables in said first base station,
　said updating the adjacency table, a new showing a neighbor cell relationship to the third cell from the first cell comprising adding an entry to the neighbor relation table,
the base station apparatus according to any one of claims 16-20.
[22.]
　The first message arrives at the first base station via the core network apparatus, the base station apparatus according to claim 16.
[23.]
　A wireless terminal,
　a wireless transceiver,
　a processor configured to control the establishment of a radio link connection for communication via the radio transceiver between said wireless terminal and base station
comprises a,
　wherein the processor , after experiencing a disorder involving cleavage of the radio link connection in the target cell during or the handover after handover from the source cell to the target cell is completed, re for requesting the re-establishment of the radio link connection the establishment request message transmitted to one different from the other cell is also the source cell and the target cell,
　receiving a rejection message indicating that the reestablishment request message is rejected by the base station controlling the other cell in response to the fact, run with the base station controlling the other cell establishment procedure of a new radio link connection,
　to follow or the establishment procedure between the establishment procedure, the source cell Physical and transmits the cell Identifier at least a first message including (PCI) to the base station controlling the other cell, the
wireless terminals.
[24.]
　The radio link connection is a Radio Resource Control (RRC) connection,
　the re-establishment request message is a RRC Connection Re-establishment Request message,
　the rejection message is a RRC Connection Re-establishment Reject message,
　the first 1 message, RRC Connection request message sent during said establishment procedure, RRC Connection Setup Complete message transmitted during the establishment procedure, or in UE the Information the Response message sent by following the established procedure there,
the radio terminal according to claim 23.
[25.]
　The re-establishment request message, the triggers the transmission of the control message from the base station controlling the other cell to the base station controlling the source cell,
　wherein the control message comprises at least include the Physical Cell Identifier (PCI) to,
wireless terminal according to claim 23 or 24.
[26.]
　The control message is to trigger an update of the adjacency table in the base station controlling the source cell,
　the update of the adjacency table, a new entry that shows the adjacent cell relationship to the other of the cell from the source cell including the fact that you want to add to the adjacency table,
wireless terminal according to claim 25.
[27.]
　The wireless terminal of the radio link connection to the source cell and any different other cells also show the target cell after experiencing a disorder involving cleavage of a radio link connection in the target cell for handover from the source cell or the source cell in response to receiving the first message that is issued when you try to reestablish a new entry indicating neighbor cell relationship to the other cells from the source cell, the base for controlling the source cell be added to the adjacency table of the station,
how to update the adjacency table with a.
[28.]
　A control method performed by the base station,
　experiences a disorder involving cleavage of a radio link connection the wireless terminal in the second cell as a first handover target cell from the first cell or the first cell If the relative aforementioned after the first cell and any and third cells having different also of the second cell attempts to reestablish the radio link connection, the first base station controlling the first cell the first comprises the sending of messages, to
　the first message, at least including the Physical cell Identifier (PCI) of the third cell,
the control method.
[29.]
　A control method performed by a wireless terminal,
　after said wireless terminal during the or the handover after handover from the source cell to the target cell is completed experienced disorders involving cleavage of a radio link connection in the target cell, transmitting a re-establishment request message for requesting the re-establishment of the radio link connection to any different other cells also of the source cell and the target cell,
　indicating that the re-establishment request message is rejected a rejection message in response to receiving from the base station controlling the other cell, performing the establishment procedure of a new radio link connection with the base station controlling the other cell, and
　the establishment or to follow the established procedure during the procedure, E-UTRAN cell Global Identifier ( ECGI) of the source cell, Physical cell Identifier (PCI), tracking Area Code (TAC), and EUTRA Absolute Radio Frequency Channel Number (EARFCN it, transmitting a first message comprising at least one base station controlling the other cell of the)
control method comprising a.
[30.]
　Non-transitory computer readable medium storing a program for causing the method according to the computer to claim 27.
[31.]
　Non-transitory computer readable medium storing a program for causing the method according to the computer to claim 28.
[32.]
　Non-transitory computer readable medium storing a program for causing the method according to the computer to claim 29.