KR20110069684A - A method for handover between base stations in a wireless mobile communication system using Ｃａｒｒｉｅｒ ｇｇｒｅｇａｔｉｏｎ - Google Patents

Abstract

A method that can be applied to a method for hard handover between base stations in a wireless mobile communication system using carrier aggregation is provided. This is a resource automatic reservation and cancellation method, a two-step handover decision method, and an automatic hysteresis adjustment method.
First, resource automatic reservation and cancellation is a method for enabling automatic reservation and cancellation of neighboring resources by connecting wireless and network signals, and for preliminary information exchange between base stations. Secondly, in the two-step handover decision method, the first step is to sort the handover candidate group based on the measured value according to the priority and determine the handover according to the result. The second step is recording to prevent unnecessary handover. The Inter-eNodeB history is analyzed to determine whether the handover decision made in step 1 is desirable or not at the historical level. Third, the automatic hysteresis adjustment method divides the relative amount of change in signal strength into a predefined class according to the degree, and also divides the currently applied hysteresis into a predefined class to apply the class of relative signal intensity change and the currently applied amount. The hysteresis is adjusted using the hysteresis class to weight the handover to be determined even if the handover is not the highest priority in the promising candidate group.

Description

Method for inter-eNodeB handover in wireless mobile communication system using CArｒｉｅｒ Ａｇｇｒｅｇａｔｉｏｎ {Method for inter eNodeB HO in wireless mobile communication system using carrier aggregation}

The present invention relates to a method for handover between base stations in a wireless mobile communication system using carrier aggregation.

The present invention is derived from the research conducted as part of the IT growth engine technology development project of the Ministry of Knowledge Economy and Korea Institute for Industrial Technology Evaluation [Task Management No .: 2006-S-003-04, Task name: Development of next generation mobile communication service platform]

The mobility management method used in a cellular mobile communication system performs access mobility management through handover according to a decision of an algorithm for managing a resource of a network on the basis of existing cell concepts.

However, a new concept of Carrier Aggregation (CA) is introduced into cellular mobile communication systems, and a new approach to the method of mobility management is required. Data transmission and reception between the same base station (eNodeB) and the user equipment (UE) in the CA environment, the transmitting side transmits data through two or more different carriers, and the receiving side receives the data received through the carriers. Eg system capacity increase, signal or data diversity, etc.).

Therefore, there is a need to provide a mobility management method suitable for various CA environments (eg, coverage mismatches, UL / DL frequency mismatches) including these CA transmission and reception aspects.

Accordingly, an object of the present invention to solve the above problems is to provide a method to be applied to the inter-eNodeB handover of the mobility management method of the user equipment (UE) in the carrier aggregation cellular mobile communication environment.

In a wireless mobile communication system using Carrier Aggregation according to an embodiment of the present invention, a method for handover between base stations includes: receiving and storing measurement information about neighbor base stations located around a serving base station; Analyzing the measurement information on the received neighbor base stations to determine resources of neighbor base stations having a downlink quality greater than a reference value as a candidate group; Reserving a resource of a neighbor base station having the largest downlink quality among the candidate groups as a resource for handover of the user terminal; Performing a handover of the user terminal to a neighbor base station having the largest downlink quality through the reserved resource; and canceling the reserved resource when the downlink quality of the reserved resource is less than the reference value. It includes.

In addition, the method for handover between eNodeBs in a wireless mobile communication system using Carrier Aggregation according to an embodiment of the present invention, measurement information received through a Radio Resource Control (RRC) interface and a Control Service Access Point (CSAP) interface Storing and processing; And preparing information exchange and resources between the eNodeBs through the X2 interface. And determining the target eNodeB based on the measurement information and the resource preparation state of the neighbor eNodeB and performing a handover. History information in which handover between inter-eNodeBs is performed when determining a target eNodeB in a candidate group in the last step may be used for handover determination.

The received measurement information includes CC-specific downlink measurement information for the current serving eNodeB and neighbor eNodeBs, and may further include information on policy and uplink measurement information measured at the source eNodeB.

The history information stores information that has been used as a serving base station while moving between eNodeBs when a user equipment (UE) has a wireless connection with a network. The information includes each CC related to a frequency band (FB). Carrier Aggregation ID related to (Component Carrier) (CAID-In the present invention, CA ID is defined as an ID capable of globally uniquely identifying the (DL) CC of the corresponding eNodeB while including information for identifying a frequency band FB. It is contemplated that the present invention may be modified in any form other than CAID mentioned in the present invention.

That is, the CA ID is any ID that can globally uniquely distinguish the CC of the base station, including which base station and which FB (what CC), and the user equipment moves to another base station (eNodeB). The history information may include the previous serving base station CA ID, the cell type, which is the information of the serving base station, and the downlink SNR quality information of the previous serving base station and the current serving base station at the time of moving with the residence time.

The history information is recorded by the current serving base station, and when the handover is performed through the X2AP, the previous record is turned over. Alternatively, the user equipment may be delivered through a handover message and a handover complete message on the RRC protocol.

When the history information is transmitted to the X2AP, the user may use a new signal message design of the X2AP of the user device or use an existing handover related message.

When the handover between the eNodeBs of the user device is determined, analyzing, by the respective CAs, a frequency of moving from the current CA to another CA using the stored history information; And performing a handover by moving to the CA having the highest frequency of movement of the user device.

In the case where the CA frequently moves the most frequently, the handover time is shorter than the reference value set by the user device or when the residence time is close to the reference value set by the wireless quality, and the residence time is short. And determining, and maintaining, by the user device, a CC set currently in use.

Meanwhile, a method for handover between eNodeBs in a wireless mobile communication system using Carrier Aggregation according to another embodiment of the present invention, when a handover preparation process for performing a handover request between base stations is not performed, a user at a source base station Determining a set of CCs to assign to the device; Performing the call preparation process by the handover request and acceptance between the source base station and neighboring base stations; When the determined CC set and the CC set received from the neighbor base stations are different, the method may include assigning one of the received CC sets to a user device to perform a handover.

The performing of the handover may include: re-executing the call preparation process when the signal quality of the determined CC set is lower than the received CC set; And assigning the CC set having the best signal quality among the CC sets received from the neighbor base stations to the user equipment to perform handover.

Among the CC sets received from the neighbor base stations, a CC set whose signal quality is higher than a minimum value of the signal quality of each CC of the source base station may be allocated to the user equipment.

According to the proposed embodiment of the present invention, when performing mobility management of the user equipment in the carrier aggregation environment (the present invention, Inter-eNodeB HO), by applying the above three methods to reduce the fast and robust handover and unnecessary handover Can be.

1 is a diagram illustrating a network system according to an embodiment of the present invention;
2 is a diagram illustrating a logical subject that manages UE mobility management in a base station in D-RRM;
3 is a view for explaining a control part of the D-RRM shown in FIG.
4 is a view for explaining a frequency reuse characteristic;
5 is a view for explaining Carrier Aggregation,
6 is a view showing another embodiment of CC planning as well as the CA environment of FIG.
7 is a view for explaining a case in which inconsistency of up / down cells occurs during CC planning;
8 is a view for explaining the type of handover (HO) used in the CC environment,
9 and 10 are diagrams for explaining the automatic resource reservation and cancellation method in a CA environment to be proposed in the present invention,
11 is a moving scenario example of UE1
12 is a flowchart for explaining a process of applying an inter-eNodeB HO;
13A-13C are flowcharts at a neighbor eNodeB
14A and 14B are flowcharts at the serving eNodeB
15 is a diagram for explaining the contents of history information and a process of storing the same;
16 to 18 are flowcharts illustrating the process 1412 of FIG. 14A in more detail.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In describing the present invention, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terminology used herein is a term used to properly express a preferred embodiment of the present invention, which may vary depending on a user, an operator's intention, or a custom in the field to which the present invention belongs. Therefore, the definitions of the terms should be made based on the contents throughout the specification.

1 is a diagram illustrating a network system according to an exemplary embodiment of the present invention.

The system shown in FIG. 1 is a technology that can be applied to all cellular mobile communication systems, and will be described below based on a next generation mobile communication system including a 3GPP Long Term Evolution (LTE) structure and a future IMT-Advanced structure. do.

The system of FIG. 1 is a 3GPP Long Term Evolution (LTE) structure in which an evolved NodeB (eNodeB) refers to a base station and is a node similar to 'NodeB + RNC' in Wideband Code Division Multiple Access (WCDMA). eNodeB 1 (20) is located in the center of cell A, eNodeB 2 (30) is located in the center of cell B.

An access gateway (aGW) 40 includes a mobility management entity (MME) and an SAE gateway, and refers to a mobile communication system management entity. The aGW 40 is a node similar to a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN) in WCDMA. The UE 10 may be a user station, and may be a mobile station capable of communicating, such as a mobile phone, a laptop, and a notebook.

From an eNodeB perspective, there is a radio interface between an eNodeB and a user equipment UE, an X2 interface that is an interface between an eNodeB, and an S1 interface that is an interface between aGW and an eNodeB. These interfaces are referred to as a Radio Resource Control (RRC) interface, an S1AP (S1 Application Part) interface, and an X2AP (X2 Application Part) in terms of a control plane in a radio network layer. In addition, such an interface is defined as a protocol, procedures for each function are defined, and messages to be used and information for each message are defined in the procedure.

The 3GPP family generally performs mobility management in the form of Network Controlled Mobile Assisted (NCMA). That is, the 3GPP series performs handover prediction, determination, and optimization in a network (eNodeB in FIG. 1), and a mobile (eg, user equipment) assists mobility management of the network. 3GPP series LTE and future LTE-Advanced, wireless access technology (Radio

Mobility management within Access Technology is based on the NCMA concept. In the cellular mobile communication system, when there is a logical dedicated wireless channel between the UE and the eNodeB, the UE may be defined as being in a connected state. In this connected state of the user equipment, mobility management is administered by the currently connected serving base station (eNodeB).

The serving base station (eNodeB) supports mobility management of the user equipment (UE) by utilizing coordination through X2AP signaling with neighbor base stations, information measured by the user equipment (UE), and measurement information in the serving base station (eNodeB). do.

FIG. 2 is a diagram illustrating a logical entity that manages UE mobility management in an eNodeB as Distributed Radio Resource Management (D-RRM). That is, the D-RRM 50 or 60 of FIG. 2 exists for each base station, and eventually resource management is directed to distributed resource management.

The D-RRM 50 or 60 of FIG. 2 is located at L3 (Layer 3) on a layer of the base stations eNodeB 1 and eNodeB 2, and is connected to the user equipment UE by RRC through an air interface. In addition, each base station is connected by X2AP, and provides CSAP (Credit-based Slot Allocation Protocol ) interfaces (CSAPL1, CSAPL2) for resource control and wireless measurement of the layers (Layer 1, Layer 2) inside the eNodeB. Have. Additionally, there is a CSAPL1L2 interface between L1 and L2.

Accordingly, the D-RRMs 50 and 60 control resources of the UE through signaling using the RRC protocol between the base stations eNodeB 1 and eNodeB 2 and the user equipment UE, or the situation in the UE (DL Meas, L2). Mea) can be reported. DL Meas means downlink measurement and L2 Meas means L2 measurement.

In addition, the D-RRM 50 may interface with the MME through signaling using the S1AP protocol and interface with a neighbor eNodeB through signaling using the X2AP protocol. In addition, the D-RRM 50 may receive a report on resource control and measurement (N.UL Meas, L2 Meas) in the eNodeB through CSAP L1 and CSAP L2 in the eNodeB. N.UL Meas means network uplink measurement and L2 Meas means network L2 measurement.

As a result, the eNodeB D-RRM 50 may perform comprehensive and systematic mobility management based on the information obtained using the various interfaces described above.

In the present invention, the function of the D-RRM 20 for performing the comprehensive and systematic mobility management is referred to as CMC (Connection Mobility Control), and the embodiment of the present invention embodies the operation for the CMC. In addition, the D-RRM 50 has a traffic & load control (TLC) function and an interference coordination control (ICC) function in addition to the CMC, and how the mobility management in the CMC should be considered by the TLC and the ICC. It is embodied in an example.

3 is a view for explaining the measurement and control signal of the D-RRM shown in FIG.

Referring to the D-RRM of FIG. 3, the D-RRM 50 of FIG. 2 is a lower layer (L1, L2) in the UE, neighbor eNodeB, MME, and D-RRM own eNodeB through RRC, X2AP, S1AP and CSAP. Interface with is possible. In addition, the D-RRM 50 uses the RRC protocol and CSAP, respectively, for the UE situation (eg, DL Meas of L1 and L2 Meas of L2 in the UE of FIG. 2) and the situation for its eNodeB (eg, eNodeB of FIG. 2). N.L2 Meas of L2 and N. UL Meas. Of L1) can be monitored and control of the measurement method at the same time.

In addition, the RRC protocol and CSAP can be used for mobility management. In addition, S1AP, which is an interface protocol between the eNodeB and the MME, may be used to perform some of mobility management functions (eg, changing a signal and data path between the eNodeB and aGW according to the change of the eNodeB). In addition, X2AP can be used to perform some of the mobility management functions (eg, handover preparation and handover information exchange between base stations).

That is, RRC is an interface protocol between the UE and the eNodeB, and X2AP is an interface protocol between the eNodeB and the eNodeB. In addition, CSAP is a Control Service Access Point between L1 (PHY) and L2 (MAC, RLC, PDCP and GTP) of the eNodeB, and S1AP is an interface protocol between the eNodeB and the MME.

RRC, X2AP, S1AP and CSAP correspond to the control plane in terms of control standard protocols and local interfaces. The purpose of measurement monitoring and control is for fast and robust handover in terms of comprehensive mobility management. D.RRM can utilize these interfaces to perform handover prediction and determination, handover coordination and optimization.

4 to 6 are diagrams for more accurately defining terms and techniques used by the present invention in describing a mobility management method in a carrier aggregation concept, and explaining frequency reuse.

4 is a diagram for explaining a frequency reuse characteristic.

Referring to FIG. 4, 'Frequency' shown in identification number '410' is a frequency band allocated to a mobile communication service provider to provide a mobile communication service in a wireless transmission method. The assigned frequency band is a band for uplink (UL) or downlink (DL). For example, assuming that a mobile operator has been allocated a frequency such as 410 of FIG. 4 for DL or UL, the base station assigns a plurality of frequency assignments to the allocated frequency bands according to the characteristics of the radio transmission scheme that the base station intends to service. , FA1, FA2, FA3).

The identification number '421' divides the allocated frequency band into FA1, FA2 and FA3. If there is inter-cell interference, the base station plans the cell with a frequency reuse factor of 3 as shown in '422'. By doing so, interference can be prevented from occurring.

The identification number '431' is a case in which a cell is sectored using a directional antenna in order to increase the total data throughput of the cell at one base station. In case of '431', three sectorings are applied to each FA by using a directional antenna with respect to one base station. '432' is a diagram illustrating an embodiment of planning a cell made as '431'.

Identification number '441' is a feature of the radio transmission method, and when there is no interference, it shows that the cell planning with only FA1, in this case, the frequency reuse rate of FA1 is 1.

The identification number '451' shows that the operator can be assigned frequencies of FA2 and FA3 even when there is no inter-cell interference, which can be cell-planned as shown in '452'. When each cell uses the same radio system, if a UE connected to a radio is moved from a FA1 cell to a FA1 cell, it is defined as an intra-frequency handover, and when a UE moves to another cell such as a FA1 cell to a FA2 cell, Can be defined as -frequency handover. In FIG. 1, the relationship between Cell A and Cell B may be the same FA or different FAs.

As described above, the frequency reuse rate may be set to 1 if there is no inter-cell interference. If inter-cell interference occurs due to a radio transmission scheme, the frequency reuse rate may be divided by the operator and the cell planed so that the frequency reuse rate becomes 1 or more. The utilization rate is set to 1, but a separate interference mitigation method may be used. Alternatively, even if the radio access method does not cause inter-cell interference, the allocated frequency may be divided and used.

In FIG. 5, when one usable frequency carrier is referred to as a component carrier (CC), the CC technology simultaneously uses a plurality of CCs (eg, CC1, CC2, CC3) in one base station according to a frequency band FB. It is a technique that can be used.

CC set used in the embodiment of the present invention may mean a set of frequency bands that can be used in the same base station for CA (Carrier Aggregation). The CA may mean a set of CCs that can be simultaneously operated by one base station, or may mean that CCs can be simultaneously operated by the same base station. An uplink (UL) CC and a downlink (DL) CC set may be Each is defined.

CC1, CC2, and CC3 may be allocated continuously, as shown at 510, or discontinuously allocated as shown at 520, and may have different frequency bands FB. In addition, one operator may be assigned all of CC1, CC2, CC3, or some CC may be allocated to different operators.

CC1, CC2 and CC3 shown in identification number '521' have the same cell coverage, as shown in '522', when there is a radio access method in which there is no interference or an interference mitigation method exists. It can be CC-planned for each base station (51, 52, 53) to operate simultaneously in one base station (for example, 51). This means that one base station (eg, 51) can transfer data by utilizing all of CC1, CC2, and CC3 according to the performance of the terminal (ie, the user equipment).

In addition, as shown in identification number '531', the total data throughput of the same base station can be increased by sectoring CC1, CC2 and CC3, which can be cell-planned as '532'.

FIG. 6 is a diagram illustrating another embodiment of CC planning as well as the CA environment of FIG. 5.

Referring to FIG. 6, it is shown that CC planning for CA may not have the same CC coverage, as shown at 522 or 532, and may not be the same number of CC sets per base station.

The identification number '611' is an example of CC planning such that the coverage of CC1 of all base stations 61, 62, and 63 is smaller than the coverage of CC2 and CC3. Identification number '612' shows a case where one base station 64 has the same coverage, the other base station 65 has a small coverage of CC1, and another base station 66 is CC-planned such that there is no CC1.

FIG. 7 is a view for explaining an example in which not only the CA environment described with reference to FIGS. 5 and 6, but also the number of UL CC sets and DL CC sets do not match (inconsistent number of up / down CC sets). to be.

In general, in the conventional cell concept, the frequency band of the UL and the frequency band of the DL form one pair, and the cells have been described based on DL coverage in FIGS. 5 and 6. This implicitly implies that the UL frequency bandwidth and the DL frequency bandwidth are identical and must be paired.

However, in a CA environment, when applying CA technology to one base station 71, the number of frequency bands for the DL and the number of frequency bands for the UL may not be the same. That is, as shown in FIG. 7, the base station 71 uses a plurality of frequency bands fc1_dl, fc2_dl, and fc3_dl for DL, while using only one frequency band fc6_ul asymmetrically for UL. have. Here, 'asymmetry' may include a mismatch between the number of CC sets of UL and DL or a difference in frequency width (FB). The frequency band 20 MHz shown in FIG. 7 is one example, and the frequency band may be larger or smaller than this.

FIG. 8 is a diagram for explaining types of handovers (HOs) that may be defined in the various CA environments described above.

Identification numbers 811 and 812 indicate handover between CC sets CC1 and CC2 operated by the same base station eNodeB 1, and are referred to as Intra-eNodeB Batch HO.

Referring to identification number '811', the first Intra-eNodeB Batch HO is generated by using CC2 while the UE uses CC1, and the second Intra-eNodeB Batch HO is generated by using CC1 while using CC2.

Referring to the identification number '812', the first type is an Intra-eNodeB CC Breakup HO that uses only one CC (CC1) and then uses two CCs (CC1, CC2) at the same time, and the second type is two CCs. It is an Intra-eNodeB CC Union HO that uses (CC1, CC2) at the same time and uses only one CC (CC1).

'821' and '822' classify the handover between base stations according to the CC situation. Referring to '821', the first type is an Inter-eNodeB Intra-CC Batch HO, in which the UE moves to CC1 of another base station (eNodeB 2) while using one CC1 at the previous base station (eNodeB 1), The second type is an Inter-eNodeB Inter-CC Batch HO, in which the UE moves to CC2 of one base station (eNodeB 2) and then moves to CC2 of another base station (eNodeB 1).

Referring to '822', the first type shows an Inter-eNodeB CC Breakup HO where the UE uses CC1 at the previous base station (eNodeB 1) and then uses CC1 and CC2 when handing over to another base station (eNodeB 2). The second type is an Inter-eNodeB CC Union HO in which a UE uses CC1 and CC2 in one base station (eNodeB 2) and then uses only one CC1 of another base station (eNodeB 1).

'831' is a CC More Split Breakup HO in which the UE uses one or more CCs and then adds a CC, a CC Less Split Breakup HO in which the number of CCs is reduced, and CC in handover. The CC Maintain Split breakup HO is shown. The call shown in '831' is called a split phenomenon, and the split phenomenon may be performed at an intra-eNodeB or an inter-eNodeB.

In general, a handover is a pair of UL and DL, and the uplink (UL) is also handed over based on the downlink (DL). The handover described with reference to FIG. 8 is described based on the downlink DL. However, in consideration of the CA environments described above, uplink (UL) and downlink (DL) handover may be performed independently or together in Intra-eNodeB. In addition, in the inter-eNodeB, uplink (UL) and downlink (DL) handover should be performed at the same time, but the split type or union type may not have the same uplink (UL) and downlink (DL).

<Handover process>

Hereinafter, the process of handover is divided into three steps.

First, the measurement monitoring and information gathering steps are described. The D-RRM 50 of the framework illustrated in FIG. 2 collects UE measurement information through RRC, collects measurement information of its eNodeB through CSAP, and prepares and exchanges information of neighboring eNodeBs through X2AP. Do this. The measured information may be, for example, information of measuring radio rink. Measurement information may be processed according to the role of each function (eg, CMC, TLC, ICC, etc.) of the D-RRM 50.

Second, handover preparation and decision stages. The CMC may prepare a current set of candidate CCs based on the processed data, and determine whether to perform a handover accordingly.

Third, handover execution step. The UE may be handed over at an appropriate time and moved to another eNodeB, ie another cell, to establish a new connection.

Optionally, in the second step, the CMC may perform a handover by accepting a request of a TLC or ICC. In the embodiment of the present invention, the handover type may be determined in consideration of the CA environment introduced when the above three steps are performed.

Meanwhile, in order for the D-RRM 50 of FIG. 2 to determine the handover type as shown in FIG. 8 according to 3GPP's Network Controlled Mobile Assisited (NCMA) handover policy, the candidate CC sets are prepared, the handover is determined, and To help execute, the UE may perform the following operations.

That is, in the information collection step, the UE measures information such as the radio link quality (L1 DL Meas.) For each CC and the state (L2 Meas.) Of the uplink (UL) traffic buffer for each CC in use, and then measures the information. Can be reported to the current serving base station (eNodeB) using the RRC protocol.

In addition, as shown in FIG. 7, since there is a situation in which uplinks are inconsistent, L1 of the base station may measure radio link quality of uplink CCs used by the UE in the base station for each UE. L1 of the base station may report the radio link quality of the measured uplink CCs and the measured uplink interference information to L3 of the base station using CSAP. Details of these measurement parameters will be described below with reference to FIG. 7.

First, referring to the case of FIG. 7, one base station uses CC4, CC5, CC6 for uplink (UL), uses CC1, CC2, CC3 for DL, and UE1 is currently present in base station 71. Assume that the connected state uses CC1, CC2, CC3 as the downlink and CC6 as the uplink. In the CA environment, measurement information related to uplink (UL) measured at the base station (eNodeB) as well as measurement information related to downlink (DL) as described below (eg buffer amount measurement and UL Radio quality measurement at the base station) , Interference measurement). That is, since inconsistency between CC up and CC down as shown in FIG. 7 may occur, measurement and management of UL and DL separately may be more suitable in a CA environment.

Parameters required for mobility management in a CA cellular environment at a base station are shown in [Table 1], [Table 2], and [Table 3]. This means that, as in FIG. 7, the eNodeB 71 uses CC1, CC2, CC3 as the downlink and uses CC4, CC5, CC6 as the uplink, and the user equipment UE1 is currently downlink to the eNodeB 71. This parameter assumes that CC1, CC2 and CC3 are used and CC6 is used as the uplink.

parameter Notation (value) (Parm 1-1)
DL Maximum Capacity per CC (DLMC) DLMC _CC1 , DLMC _CC2 , DLMC _CC3 (Parm 1-2)
UL Maximum Capacity by CC (ULMC) ULMC _CC4 , ULMC _CC5 , ULMC _CC6 (Parm 1-3)
UL / DL PRB Usage Policy by CC and / or Location by Interference Coordination Policy For example, policies such as restricting or encouraging the use of PRBs by CC based on the current location of UE-specific cells according to the FFR policy (information that is predefined and may change semi-statically). (Parm 1-4)
Total quality to be guaranteed for that UE by UE In case of _UE1, ULGQ _{UE1 ,} DLGQ _UE1 (Parm 1-5)
CC split quality to satisfy ULGQ or DLGQ of corresponding UE by UE In case of UE1 (see Fig. 7 dotted line),
ULCCGQ _UE1CC6 ,
DLCCGQ _UE1CC1, DLCCGQ _UE1CC2 , DLCCGQ _UE1CC3,
Where ULGQ _UE1 = ULCCGQ _UE1CC6,
DLGQ _UE1 = DLCCGQ _UE1CC1 + DLCCGQ _UE1CC2 + DLCCGQ _UE1CC3 (Parm 1-6)
Reference value of physical signal quality measured for each CC to guarantee DLCCGQ or ULCCGQ for each CC used by the UE in the UE, the current serving base station (eNodeB) of the UE In case of UE1 (see Fig. 7 dotted line),
ULCCTH _UE1CC6 ,
DLCCTH _UE1CC1 , DLCCTH _UE1CC2 , DLCCTH _UE1CC3

Measurement values measured at L2 and L1 of the base station are shown in [Table 2].

Layer parameter Measures L2
(N. L2 Meas box at eNodeB L2 in FIG. 2) (Parm 2-1)
DL Available Capacity by CC (DLCCAC) DLCCAC _CC1 , DLCCAC _CC2 , DLCCAC _CC3 (Parm 2-2)
UL Available Capacities by CC (ULCCAC) ULCCAC _CC4 , ULCCAC _CC5 , ULCCAC _CC6 (Parm 2-3)
DL Traffic Buffer Amount (DLBA: DL Buffer Amount) Currently Used by UE by UE DLCCBA _UE1CC1 , DLCCBA _UE1CC2 , DLCCBA _UE1CC3 L1
(Meas. Box at eNodeB L1 in FIG. 2) (Parm 2-4)
By CC UL Quality Currently Used by UL (ULCCQ) ULCCQ _{UE1CC6 for} UE1 (Parm 2-5)
The level of interference from another base station (eNodeB) as a resource area for each CC used by the UE (ULCCIL: UL CC Interference Level) ULCCIL _{UE1CC6 for} UE1

Measurement values measured at L2 and L1 of the user device are shown in [Table 3].

Layer Measures L2
(L2 Meas. Box at UE L2 in FIG. 2) (Parm 3-1)
UL traffic buffer amount per CC and CC currently used by UE In case of UE1 (see FIG. 7 dotted line),
ULCCBA _UE1CC6 L1
(L1 Meas. Box at UE L1 in FIG. 2) (Parm 3-2)
DL quality per base station and CC currently measured at UE (DLENBCCSNR)
The D-RRM of the serving base station may control to limit the base station target to be measured by the UE.
The serving base station may control to perform periodic reporting and / or event reporting on DLENBCCSNR.) UE1 (see FIG. 7 dotted line and if the serving base station is eNodeB1 and neighboring base stations are eNodeB2, eNodeB3)
DLENBCCSNR _{UE1CC1eNodeB1,}
DLENBCCSNR _{UE1CC2eNodeB1,}
DLENBCCSNR _{UE1CC3eNodeB1}
DLENBCCSNR _{UE1CC1eNodeB2,}
DLENBCCSNR _{UE1CC2eNodeB2,}
DLENBCCSNR _{UE1CC3eNodeB2}
DLENBCCSNR _{UE1CC1eNodeB3,}
DLENBCCSNR _{UE1CC2eNodeB3,}
DLENBCCSNR _{UE1CC3eNodeB3} Level of interference for each CC coming from another base station (eNodeB) in a resource area used by the corresponding UE for each UE (DLCCIL, DL CC Interference Level) For UE 1
DLCCIL _UE1CC1 , DLCCIL _UE1CC2 , DLCCIL _UE1CC2

In [Table 3], the UL buffer amount and the DL interference level may be divided into upper, middle, and lower levels, for example. As a result, for mobility management in CA environment, D-RRM manages and updates semi-static information as shown in [Table 1], information measured through CSAP at its base station as shown in [Table 2], and As shown in [Table 3], information measured through the UE can be obtained through RRC. That is, the D-RRM performs mobility management in the CA environment based on the information as shown in [Table 1] and these measurement information as shown in [Table 2] and [Table 3].

In a CA environment, handover can occur in three main categories.

Firstly, when the SNR quality of currently connected CCs is deteriorated. Secondly, to mitigate interference on the system side. Third, handover occurs when a system-wide load distribution request is required according to traffic conditions.

In the embodiment of the present invention, the first category is responsible for the functions required by the CMC of the D-RRM, the second category is responsible for the ICC, the third category will be described by taking the case of the TLC.

First, the second category is described in detail as follows.

If there is an Interference Coordination Control (ICC) function in the D-RRM 50, the ICC interferes with UL / DL Physical Resource Block (PRB) usage policy and Proactive Approach for each CC according to the Interference Coordination Policy described in [Table 1]. The interference control can be called Interference Indication. Proactive Approach means that interference prevents and controls interference according to predefined interference rules.

In addition, the ICC may perform interference control using the Reaction Approach according to the measurement result of the CC-specific interference levels (ULCCIL, DLCCIL) used by the corresponding UE described above with reference to [Table 2] and [Table 3]. In the present invention, the information received from the ICC by the CMC by interference control of the ICC is defined in the present invention. Reaction Approach means to control the interference according to the result of the interference.

In terms of proactive, the meaning of Interference Indication means that the CC used by the UE is to refrain or recommend the use of a specific PRB resource, or may indicate that the CC is not used or used. .

In addition, in the reactive aspect, the meaning of Interference Indication may be to request an action according to the level of interference occurring in the CC used by the UE. For example, since the 'phase' has a lot of interference in the PRB being used in the corresponding CC used by the UE, as a countermeasure at this time, it may be moved from the same CC to another PRB, or the movement to another CC may be considered.

That is, the embodiment of the present invention focuses on the CA environment, and the work of moving from the same CC to another PRB is performed by the MAC scheduler. Therefore, the above-described Interference Indication of the ICC is interpreted to mean that the UE does not use the CC due to the interference problem, and the CMC of the D-RRM 50 confirming the Interference Indication excludes the use of the CC. It is described as.

The third case is described in more detail as follows.

If there is a Traffic Load Control (TLC) function in the D-RRM 50, the TLC function performs overload indication control by considering and referring to the above-described information with reference to [Table 1], [Table 2], and [Table 3]. can do. The information considered among the above-described information is, for example, the maximum capacitor (DLMC (Parm 1-1), ULMC (Parm 1-2)) of the downlink (DL) and uplink (UL) for each CC, quality ((Parm) 1-4), (Parm 1-5)). In addition, the information referred to in the above-described information may be, for example, available capacities of UL and DL (DLCCAC (Parm 2-1), ULCCAC (Parm 2-2)), and traffic buffer amounts of UL and DL (DLCCBA (Parm). 2-3), ULCCBA (Parm 3-1)).

Overload Indication control means that the TLC of the D-RRM 50 informs the CMC to restrict any UE from using any CC based on the above-described information. When the CMC receives the determined overload indication from the TLC, when the UE is using the CC, the CMC may execute the most suitable type of handover in a state in which the use of the CC is excluded.

9 and 10 are diagrams for explaining an automatic resource reservation and cancellation method in a CA environment to be presented in the present invention.

In FIG. 9, the hatched ellipse means the DLENBCCSNR for the neighboring cell and the hatched ellipse means the DLENBCCSNR for the serving cell. In addition, in FIG. 9, an ellipse is a measurement value measured at L1 of the UE illustrated in FIG. 2 and is a value collected by the D-RRM of the current serving base station using the RRC interface of FIG. 3. The measured value measured at L1 of the UE is DL Meas. Or DLENBCCSNR (Parm 3-2) in [Table 3], which is the value for the CC of the serving base station and neighbor base stations that the UE measures at the current location.

In addition, the events cited in the present invention are A4-1, A4-2, A3-1. A4-1 means a case where the DLENBCCSNR of the neighboring base station becomes larger than the reference value TH1, and A4-2 means a case where the DLENBCCSNR of the neighboring base station becomes smaller than the reference value TH1. A3-1 means a case where the DLENBCCSNR of the neighboring base station becomes larger than the DLENBCCSNR of the current serving base station.

In the present invention, TH1 of A4-1 is referred to as T _PREP , and TH1 of A4-2 is referred to as T _RMT . T _PREP and T _RMT may be set identically or differently. When the DLENBCCSNR of the neighboring base station becomes larger than T _PREP , that is, when an A4-1 event occurs, the serving base station prepares resources by exchanging information with the neighboring base station. In addition, when the DLENBCCSNR of the neighboring base station becomes smaller than the T _RMT , the serving base station releases the prepared resource through information exchange with the corresponding base station.

FIG. 10 is a diagram logically illustrating a location-specific area determined on the premise that T _RMT and T _PREP of FIG. 9 are the same.

In FIG. 10, eNodeB 1, eNodeB 2, and eNodeB 3 are base stations, and an inner cell region (ICR), a cell edge region-type I (CER-I), and a cell edge region-type II (CER-II) are located in the UE. Type of region that can be.

The UE may be located in ICR, CER-I or CER-II according to A4-1, A4-2 event satisfaction condition for neighboring DLENBCCSNR values. That is, the fact that the UE is located in the ICR means that DLENBCCSNR values for all CCs of neighboring base stations are all smaller than T _PREP .

The location of the UE in CER-I means that the DLENBCCSNR values for all CCs of neighboring base stations are greater than T _PREP and also exist only in one neighboring base station. In addition, the location of the UE in CER-II means that the DLENBCCSNR values for all CCs of neighboring base stations are greater than T _PREP and are also present in two or more neighboring base stations.

In the CA environment proposed in the present invention, automatic resource reservation and cancellation performs resource reservation and cancellation for neighboring base stations according to the region shown in FIG. 10. Thus, when handover is determined at a cell boundary, handover is performed immediately. Can be. As a result, resource automatic reservation is made through neighboring base stations that cause A4-1. This is because causing A4-1 means that the quality of the neighboring base station is excellent because the DL quality DLENBCCSNR is greater than TH1. In addition, automatic resource cancellation occurs through neighboring base stations that cause A4-2. This is because the DL quality DLENBCCSNR is greater than TH1, which means that the serving base station has better quality than the neighboring base station.

11 and 12 are scenarios and flowcharts for explaining a process of applying an inter-eNodeB HO.

FIG. 11 relates to a scenario in which a UE moves from eNodeB 1 to eNodeB 2 under the assumption that T _RMT and T _PREP are the same. When the UE is at location 1110, if the DLENBCCSNR for any CCs of eNodeB 2 is greater than T _PREP , then the currently serving base station eNodeB 1 may make eNodeB 2 an Advanced Resource Preparation (eg, 1215 of FIG. 11). Induce.

In addition, when the UE is at location 1120, if an A3-1 event occurs in which e. Determine and execute the handover. As a result, the serving base station is changed from eNodeB 1 to eNodeB 2, and eNodeB 1 becomes a neighbor base station of eNodeB 2.

When the UE is at location 1130, if an A4-2 event occurs in which the DLENBCCSNR value for CCs for eNodeB 2 becomes less than T _RMT , the current serving base station eNodeB 2 is sent to the corresponding neighboring base station eNodeB 1. Instructs to perform a Resource Release (eg, 1230 of FIG. 11).

The flow according to the scenario of FIG. 11 is shown in FIG. 12.

According to the scenario described with reference to FIG. 11, automatic resource reservation, handover decision and execution, and automatic resource cancellation of FIG. 12 are sequentially performed.

First, automatic resource reservation and cancellation in the present invention is made based on the DLENBCCSNR measured by the UE. For the CCs of neighboring base stations causing A4-1, the serving base station and the neighboring base station transmit and receive a Handover Request (1210 of FIG. 12) and a Handover Request Ack (1220 of FIG. 12) by using an X2AP protocol message. 1215 of FIG. 12 is enabled.

In addition, with respect to the CC of the neighbor base stations causing A4-2, Resource Release (1280 of FIG. 12) is enabled by using an X2AP protocol message called UE Context Release (1275 of FIG. 12).

The DLENBCCSNR values measured at the UE can be provided to the serving base station by the UE using an RRC protocol message called a Measurement Report, and the serving base station determines the event directly by the CMC of the D-RRM based on the DLENBCCSNR collected at the D-RRM. Can be. Alternatively, the UE may directly determine an event by measurement control and provide the determined event to the serving base station using an RRC protocol message called a measurement report (1205, 1225, and 1270 of FIG. 12).

In operation 1205, the UE may report the A4-1 event in the form of a measurement report message. The A4-1 event is an event according to DLENBCCSNR at the measured neighbor base stations (eNodeB 2, eNodeB 3). A4-1 event is a result of measuring the SNR quality (DLENBCCSNR of Table 3) for the reference signal of each CC of the neighboring base station (eNodeB 2, 3) the user equipment (UE), the measurement result is in the network It means that it is higher than the threshold T _PREP .

The measurement report message is reported to the current serving base station (eNodeB 1) through the RRC interface, and a handover request and a handover request response (Handover Request Ack), which will be described later, are transmitted in the form of X2AP to transmit A4-1. Enable Advanced Resource Preparation (1215 of FIG. 12) for the corresponding neighbor base stations that caused it.

In operation 1210, the current serving base station eNodeB 1 may transmit a handover request to the neighbor base stations eNodeB 2 and eNodeB 2 that cause A4-1 by using the X2AP. In the case of FIG. 11, the base station generating the A4-1 event at the location 1110 of the UE sends a handover request to the eNodeB 2.

Information to be included in steps 1210 and 1220 or steps 1235 and 1245 to be described later in a CA environment is shown in [Table 4]. In addition, [Table 4] shows an embodiment of information actually entered under the following assumption.

The assumptions for Table 4 are as follows.

1. As shown in FIG. 7, the eNodeB 71 uses CC1, CC2, and CC3 as downlinks, uses CC4, CC5, and CC6 as uplinks, and eNodeB 1 and eNodeB 2 in FIGS. 11 and 12 are eNodeBs 71. Corresponds to).

2. UE1 uses CC1, CC2, CC3 as the downlink and CC6 as the uplink in eNodeB 1, and uses CC3 as the downlink and CC5 as the uplink after handover to eNodeB 2.

3. Handover is performed according to the UE1 movement path shown in FIG. 11 and the procedure of FIG. 12.

4. Like the base station 62 of FIG. 6, the eNodeB1 has full coverage only in CC2 and CC3 in the downlink, and CC1 does not have full coverage. In addition, uplink is operated to have only full coverage of CC5, CC6 among CC4, CC5, CC6.

5. The eNodeB2 operates CC1, CC2, CC3 with full coverage on the downlink as in the base station 64 of FIG. 6, and the uplink operates CC4, CC5, CC6 with full coverage.

X2AP message Information group and information Handover request
(4-1) (Parm 4-1-1)
UE ID (information that identifies the UE, in any form) UE1 ID (Parm 4-1-2)
Serving eNodeB ID {(Parm 1-4) ULGQ, DLGQ} of Table 1 eNodeB 1 {ULGQ _UE1 = 30, DLGQ _UE1 = 40} (Parm 4-1-3)
Serving eNodeB ID {(Parm 1-5) ULCCGQ, DLCCGQ} of Table 1 eNodeB 1 {DLCCGQ _CC1 = 13, DLCCGQ _CC2 = 12, DLCCGQ _CC3 = 15, ULCCGQ _CC6 = 30} (Parm 4-1-4)
CC set of corresponding base stations to send a handover request among neighboring base stations having DLENBCCSNR greater than T _PREP in (Parm 3-2) of Table 3
Neighbor eNodeB ID {DL-CC set} to send Handover Request eNodeB 2 {CC2, CC3}
Based on information managed in the eNodeB 1 D-RRM at position 1110 of FIG. 11, it is assumed that DLENBCCSNR _{UE1CC1eNodeB2 and} DLENBCCSNR _{UE1CC2eNodeB2} of eNodeB 2 satisfy A4-1. (Parm 4-1-5)
Serving eNodeB ID {use CC set}
-(Added for convenience of information or explanation that can be estimated through Parm 4-13) eNodeB 1 {DL (CC1, CC2, CC3), UL (CC6)}
(Parm 4-1-6)
Serving eNodeB ID {Full coverage DL CC Set}
eNodeB 1 {DL (CC2, CC3), UL (CC5, CC6)}
(Parm 4-1-7)
Maximum number of supported CCs in UE1
UEDLCapa, UEULCapa UEDLCapa (3)
UEULCapa (3)) Handover Request ACK
(4-2) (Parm 4-2-1)
UE ID (information that identifies the UE, in any form) UE1 ID (Parm 4-2-2) Success or Failure
Only if successful (Parm 4-5, 4-6, 4-7) is valid information) Success (Parm 4-2-3)
Neighbor eNodeB ID {Available DU-CC Set, UL-CC Set} eNodeB 2 {DL (CC1, CC2, CC3), UL (CC5)}
Based on the information managed in the eNodeB 2 D-RRM at position 1110 of FIG. 11, the available DL CC set is determined as CC3 when the UE is transferred to the eNodeB 2 by handover, and the available UL CC set is 5 Is assumed. (Parm 4-2-4)
Neighbor eNodeB IDs {(Parm 1-4) ULGQ, DLGQ} in Table 1 eNodeB 2 {ULGQ _UE1 = 30, DLGQ _UE1 = 40} (Parm 4-2-5)
Neighbor eNodeB IDs {(Parm 1-5) ULCCGQ, DLCCGQ} in Table 1 eNodeB 2 {DLCCGQ _CC1 = 10, DLCCGQ _CC2 = 8,
DLCCGQ _CC31 = 22, ULCCGQ _CC5 = 30} UE Context Release
(4-3) (Parm 4-3-1)
UE ID (information that identifies the UE, in any form) UE1 ID (Parm 4-3-2)
ENodeB ID to receive UE Context Release {use CC set of corresponding neighboring base station stored in serving base station} eNodeB 1 {DL (CC1, CC2, CC3), UL (CC6)}

On the other hand, if the UE is connected to the network, the UE has a serving base station and also has a neighboring base station of 1-tier around the serving base station. That is, the D-RRM of the base station may be in the "serving (source) [CMC] state" or the "neighbor (target) [CMC]" state for the UE connected to the network and may be "serving (source) [CMC] by handover. ] "State may be" Neighbor (Target) [CMC] "state, and conversely," Neighbor (Target) [CMC] "state may be" Serving (source) [CMC] ". This relationship is shown in the states of 1300 and 1400 in FIGS. 13A-13C and FIGS. 14A and 14B.

Advanced resource preparation of 1215 in the automatic resource reservation step of FIG.

(UE1 1110 position in FIG. 11, 131 flow in FIG. 13A, 142 flow in FIG. 14B)

Advanced Resource Preparation is a process of preparing a handover in advance by transmitting a handover request to the CC of the neighboring base station that generated the A4-1 event in advance. In this case, the CA environment is different from the existing handover, and the neighboring base station receiving the handover request prepares a handover for the corresponding UE with its own CC set. The CMC of the D-RRM of the neighbor base station may be dedicated to handover to one of its own CCs or may be distributed to multiple CCs. Then, the neighbor base station transmits to the serving base station through the Handover Request Ack how its CC is distributed.

131 of FIG. 13A is a flowchart illustrating an advanced resource preparation procedure of 1215 of FIG. 12.

In step 1311, the neighbor base station (eNodeB 2) receives a handover request for Advanced HO Preparation purposes. The received handover request includes information corresponding to message 4-1 of Table 4 below.

In step 1312, the neighbor base station eNodeB 2 performs CC determination and resource reservation based on the received information and its own situation.

In step 1313, the neighbor base station (eNodeB 2) includes the information corresponding to the message 4-2 of Table 4 in the handover request arc and delivers to the serving base station (eNodeB 1). At this time, the process of determining the information to send to the serving base station is as follows.

In addition, the Prompt Resource Preparation 1240 in the handover decision and execution step of FIG. 12 to be described later is similar to the Advanced Prompt Preparation 1215 (131 of FIG. 13A). However, whether the Handover Request trigger at the serving base station (eNodeB 1) is generated by the A4-1 event.

[Algorithm A] Advanced HO Preparation-Processing at eNodeB2 when eNodeB2 receives a Handover Request message (4-1 in Table 4) from eNodeB1

1. Obtain information of its own base station (eNodeB 2).

  1.1 Check the current CC

Yes. eNodeB 2 {DL (CC1, CC2, CC3), UL (CC4, CC5, CC6)}

  1.2 Check Full Coverage CC

Yes. eNodeB 2 {DL (CC1, CC2, CC3), UL (CC4, CC5, CC6)}

  1.3 Identify DLCCAC (Parm 2-1 in Table 2) and ULCCAC (Parm 2-2 in Table 2) at its base station, limited to the Full Coverage CC of 1.2.

Yes. DLCCAC _CC1 = 10, DLCCAC _CC2 = 8, DLCCAC _CC3 = 30 →

ULCCAC _CC4 = 5, DLCCAC _CC5 = 30, DLCCAC _CC6 = 0 →

Sort by ccindex as below

Yes.

IE1_3.num = 3 {.DLCCAC [0] .ccindex = 1 DLCCAC [0] .value = 10,

            .DLCCAC [1] .ccindex = 2 DLCCAC [1] .value = 8,

            .DLCCAC [2] .ccindex = 3 DLCCAC [2] .value = 30)

IE1_3.num = 3 {.ULCCAC [0] .ccindex = 4 ULCCAC [0] .value = 5,

            .ULCCAC [1] .ccindex = 5 ULCCAC [1] .value = 30,

.ULCCAC [2] .ccindex = 6 ULCCAC [2] .value = 0)

2. Process the information in 4-1 message in [Table 4].

2.1 In the CC that satisfies (Parm 4-1-6), (Parm 4-1-3) is sorted by uplink and downlink, respectively, in order of increasing order. In the case of DL, the condition that satisfies (Parm 4-1-4) of 4-1 message of [Table 4] can be included.

Yes. DL -eNodeB 1 {DLCCGQ _CC1 = 13, DLCCGQ _CC2 = 12, DLCCGQ _CC3 = 15}

UL -eNodeB 1 {ULCCGQ _CC6 = 30}

2.2 If the total sum of entities sorted in 2.1 is greater than the total sum of DL (or UL) CCAC []. Values of 1.3, then all processes are terminated and Handover, a failure response to the 4-1 message in Table 4, is completed. Send a Request Failure. In the small case, if the ccindex has the same priority, then compare the same (eg x) with the same ccindex (eg x), and if the CCGQccx is greater than the DLCCAC []. Value with ccindex = x, then the difference is ccindex. Accumulate with = none.

Yes. Total sum of entities sorted in 2.1

eNodeB1 DLGQ = 13 + 12 + 15 = 40

Yes. Total sum of entities sorted in 2.1 (UL)

eNodeB1 ULGQ = 30

Yes. Total of eNodeB2 DLCCAC []. Values in 1.3 = DLCCAC [0] .value (10) of ccindex = 1 + DLCCAC [1] .value (8) of ccindex = 2 + DLCCAC [2] .value of ccindex = 3 ( 30) = 48

Yes. Total of eNodeB2 ULCCAC []. Values in 1.3 = DLCCAC [0] .value (5) of ccindex = 4 + DLCCAC [1] .value (30) of ccindex = 5 + DLCCAC [2] .value of ccindex = 6 ( 0) = 35

Yes.

[DL] In the above example, since the total sum (DL) 40 of the entities sorted in 2.1 is not greater than the total 48 of DLCCAC []. Value, Handover Request Failure is not handled but UL is also confirmed.

[UL] Likewise, in the above example, since the total sum (UL) 30 of the entities sorted in 2.1 is not greater than the total 35 of ULCCAC []. Value, Handover Request Failrue processing is not performed. If either UL or DL does not meet the conditions, Handover Request Failure is handled.

Yes. "In that case cumulatively storing the difference as ccindex = none".

[DL]

If ccindex = 1, eNodeB 1 {DLCCGQ _CC1 = 13} and eNodeB2 DLCCAC [0] .value = 10, so the former is larger than the latter, so the difference (13-10 = 3) is stored in DLCCGQccnone = 3. Then, add IE2_2 entry (ccindex = 1, value = 10) with IE2_2 entry (ccindex = 1, value = 10)

If ccindex = 2, eNodeB 1 {DLCCGQ _CC2 = 12} and eNodeB2 DLCCAC [1] .value = 8, so the former is larger than the latter, so the difference (12-8 = 4) accumulates 4 to the existing DLCCGQccnone = 3 value. In addition, DLCCGQccnone = 7. And add IE2_2 entry (ccindex = 2, value = 8)

If ccindex = 3, there is no change in the existing cumulative value DLCCGQccnone = 7 since the former is smaller than the latter because eNodeB 1 {DLCCGQ _CC3 = 15} and eNodeB2 DLCCAC [2] .value = 30. And add IE2_2 entry (ccindex31, value = 15)

 [UL]

If ccindex = 6, eNodeB 1 {ULCCGQ _CC6 = 30} and eNodeB2 ULCCAC [3] .value = 0, so the former is larger than the latter, so the difference between the former and the latter (30-0 = 30) is DLCCGQccnone = 30. And add IE2_2 entry (ccindex = none, value = 30)

Yes.

In the above example, the IE for the DL is determined as follows.

IE2_2.num = 4 {.DLCCGQ [0] .ccindex = 1 DLCCGQ [0] .value = 10,

            . DLCCGQ [1] .ccindex = 2 DLCCGQ [1] .value = 8,

            . DLCCGQ [2] .ccindex = 3 DLCCGQ [2] .value = 15,

. DLCCGQ [3] .ccindex = none DLCCGQ [3] .value = 7)

In the above example, UL is determined as follows.

IE2_2.num = 1 { . ULCCGQ [0] .ccindex = none ULCCGQ [0] .value = 30 }

3. Perform processing to determine Parm 4-2-3, 4-2-4, 4-2-5 on message 4-2 in Table 4.

3.1 Initializing Result Structure

Initialize Result structure ((DL or UL) Result.num (DL or UL) Result. (DL or UL) CCGQ []. Ccindex, Result. (DL or UL) CCGQ []. Num)-This is [Table 4] Refers to a structure in which a result for generating a 4-2 message value is stored.

3.2 There are several ways in which eNodeB2 determines the handover type. In this case, the result information is obtained through the following three steps of the algorithm in which the split does not occur while maintaining the CC used by the eNodeB1. However, the algorithm may be modified to minimize the splite, and the number of CCs supported by the UEULCapa and the UEDLCapa in the information (Parm 4-1-7) of the 4-1 message of Table 4 may be considered as additional conditions. .

3.2.1 Algo. 3.2.1

Algo. 3.2.1 == start

Step. One

(DL or UL) Result.num = 0;

for (i = 0; i <(DL or UL) IE2_2.num; i ++)

{ //One

   for (j = 0; j <(DL or UL) IE1_3.num; j ++)

   { //2

      if (IE2_2. (DL or UL) CCGQ [i] .ccindex == IE1_3. (DL or UL) CCAC [j] .ccindex)

            {// 3

         if (IE2_2. (DL or UL) CCGQ [i] .value = <IE1_3. (DL or UL) CCAC [j] .value)

               { //4

          (DL or UL) Result. (DL or UL) CCGQ [(DL or UL) Result.num]. Ccindex = IE1_3. (UL or DL) CCAC [j] .ccindex;

           (DL or UL) Result. (DL or UL) CCGQ [(DL or UL) Result.num] .value = (DL or UL) Result. (DL or UL) CCGQ.value + IE2_2. (DL or UL) CCGQ [i] .value;

               IE1_3. (UL or DL) CCAC [j] .value = IE1_3. (UL or DL) CCAC [j] .value-IE2_2. (DL or UL) CCGQ [i] .value;

                     (DL or UL) Result.num ++;

             } //4

         } // 3

   } //2

} //One

Yes. Step. After 1

IE1_3.num = 3 {.DLCCAC [0] .ccindex = 1 DLCCAC [0] .value = 0,

     .DLCCAC [1] .ccindex = 2 DLCCAC [1] .value = 0,

     .DLCCAC [2] .ccindex = 3 DLCCAC [2] .value = 15}

IE1_3.num = 3 {.ULCCAC [0] .ccindex = 4 ULCCAC [0] .value = 5,

      .ULCCAC [1] .ccindex = 5 ULCCAC [1] .value = 30,

      .ULCCAC [2] .ccindex = 6 ULCCAC [2] .value = 0)

 (DL) Result.num = 3 {.DLCCGQ [0] .ccindex = 1 DLCCGQ [0] .value = 10,

     .DLCCGQ [1] .ccindex = 2 DLCCGQ [1] .value = 8,

           .DLCCGQ [2] .ccindex = 3 DLCCGQ [2] .value = 15}

(UL) Result.num = 0 {}

Step. 2

Sort IE1_3 information in order of value size.

Yes. Step. After 2

IE1_3.num = 3 {.DLCCAC [0] .ccindex = 3 DLCCAC [0] .value = 15,

     .DLCCAC [1] .ccindex = 1 DLCCAC [1] .value = 0,

     .DLCCAC [2] .ccindex = 2 DLCCAC [2] .value = 0}

IE1_3.num = 3 {.ULCCAC [0] .ccindex = 5 ULCCAC [0] .value = 30,

      .ULCCAC [1] .ccindex = 4 ULCCAC [1] .value = 5,

.ULCCAC [2] .ccindex = 6 ULCCAC [2] .value = 0)

Step. 3, xx, bool are variables representing integers

No 3;

xx = (DL or UL) Result.num;

for (i = 0; i <(DL or UL) IE2_2.num; i ++)

{ //One

if (IE2_2. (DL or UL) CCGQ [i] .ccindex == none)

{ //2

for (j = 0; j <(DL or UL) IE1_3.num; j ++)

{// 3

Algo 3.2.1-1

} // 3

  } //2

}//One

(DL or UL) Result.num = xx;

Algo. 3.2.1 == end

Algo 3.2.1-1 == start

if (IE1_3. (DL or UL) CCAC [j] .value> 0)

{

  If (IE2_2. (DL or UL) CCGQ [i] .value <= IE1_3. (DL or UL) CCAC [j] .value)

       {

Algo 3.2.1-1-1

       }

      else

      {

Algo 3.2.1-1-2

}

if (IE2_2. (DL or UL) CCGQ [i] .value <= 0) break; // ccindex = none only

}

Algo 3.2.1-1 == end

Algo 3.2.1-1-1 == Start

bool = 0;

for (k = 0; k <((DL or UL) Result.num); k ++) // 4

{

  if (Result. (DL or UL) CCGQ [k] .ccindex == IE1_3. (DL or UL) CCAC [j] .ccindex)

      {

(DL or UL) Result. (DL or UL) CCGQ [k] .value = (DL or UL) Result. (DL or UL) CCGQ [k] .value + IE2_2. (DL or UL) CCGQ [i]. value;

IE1_3. (UL or DL) CCAC [j] .value = IE1_3. (UL or DL) CCAC [j] .value-IE2_2. (DL or UL) CCGQ [i] .value;

bool = 1;

IE2_2. (DL or UL) CCGQ [i] .value = 0; // 3 escape condition

break; // 4 escape

      }

} //4

if (bool! = 1)

{

(DL or UL) Result. (DL or UL) CCGQ [xx] .ccindex = IE1_3. (DL or UL) CCAC [j] .ccindex;

(DL or UL) Result. (DL or UL) CCGQ [xx] .value = (DL or UL) Result. (DL or UL) CCGQ [xx] .value + IE2_2. (DL or UL) CCGQ [i]. value;

IE1_3. (UL or DL) CCAC [j] .value = IE1_3. (UL or DL) CCAC [j] .value-IE2_2. (DL or UL) CCGQ [i] .value;

IE2_2. (DL or UL) CCGQ [i] .value = 0; // 3 escape condition

xx = xx + 1

}

Algo 3.2.1-1-1 == end

Algo 3.2.1-1-2 == start

bool = 0;

for (k = 0; k <((DL or UL) Result.num); k ++) // 5

{

  if (Result. (DL or UL) CCGQ [k] .ccindex == IE1_3. (DL or UL) CCAC [j] .ccindex)

      {

(DL or UL) Result. (DL or UL) CCGQ [k] .value = (DL or UL) Result. (DL or UL) CCGQ [k] .value + IE1_3. (DL or UL) CCAC [j]. value;

IE1_3. (UL or DL) CCAC [j] .value = 0;

IE2_2. (DL or UL) CCGQ [i] .value = IE2_2. (DL or UL) CCGQ [i] .value-IE1_3. (DL or UL) CCAC [j] .value;

bool = 1;

break; // 5 Escape

}

} // 5

if (bool! = 1)

{

(DL or UL) Result. (DL or UL) CCGQ [xx] .ccindex = IE1_3. (DL or UL) CCAC [j] .ccindex;

(DL or UL) Result. (DL or UL) CCGQ [xx] .value = (DL or UL) Result. (DL or UL) CCGQ [xx] .value + IE1_3. (DL or UL) CCAC [j]. value;

  IE1_3. (UL or DL) CCAC [j] .value = 0;

  IE2_2. (DL or UL) CCGQ [i] .value = IE2_2. (DL or UL) CCGQ [i] .value-IE1_3. (DL or UL) CCAC [j] .value;

  xx = xx + 1

  (DL or UL) Result.num = xx;

  go to no3;

}

Algo 3.2.1-1-2 == end

Yes. Step. After 3, Algo 3.2.1-1-1 is applied in this example.

IE1_3.num = 3 {.DLCCAC [0] .ccindex = 3 DLCCAC [0] .value = 8,

     .DLCCAC [1] .ccindex = 1 DLCCAC [1] .value = 0,

     .DLCCAC [2] .ccindex = 2 DLCCAC [2] .value = 0}

IE1_3.num = 3 {.ULCCAC [0] .ccindex = 5 ULCCAC [0] .value = 0,

      .ULCCAC [1] .ccindex = 4 ULCCAC [1] .value = 5,

.ULCCAC [2] .ccindex = 6 ULCCAC [2] .value = 0}

IE2_2.num = 4 {.DLCCGQ [0] .ccindex = 1 DLCCGQ [0] .value = 10, // no change

   .DLCCGQ [1] .ccindex = 2 DLCCGQ [1] .value = 8, // no change

   .DLCCGQ [2] .ccindex = 3 DLCCGQ [2] .value = 15, // no change

.DLCCGQ [3] .ccindex = none DLCCGQ [3] .value = 0) // change from 7 to 0

IE2_2.num = 1 {. ULCCGQ [0] .ccindex = none ULCCGQ [0] .value = 0} // 30 → 0

(DL) Result.num = 3 {.DLCCGQ [0] .ccindex = 1 DLCCGQ [0] .value = 10, // no change

     .DLCCGQ [1] .ccindex = 2 DLCCGQ [1] .value = 8, // no change

     .DLCCGQ [2] .ccindex = 3 DLCCGQ [2] .value = 22} // 15 → 2

(UL) Result.num = 1 {.ULCCGQ [0] .ccindex = 5 ULCCGQ [0] .value = 30} // add entry, assign value 0 → 30 to ccindex = 5

4. According to the result from 3, make the message 4-2 in [Table 4].

If the result of 4.1 3 fails to comply with the requirements of (Parm 4-1-2) in [Table 4], (Parm 4-2-2) is FAIL (described above as Handover Request Failure), and if accepted, SUCCESS to be.

4.2 In case of SUCCESS, extract the ccindex and value of (DL or UL) CCGQ directly from the result to construct (Parm 4-2-5), obtain ULGQ through the sum of ULCCGQ for UL, and calculate DLCCGQ for DL. Find the DLGQ through the sum. Then, using the obtained values, (Parm 4-2-4) is constructed, and only ccindex is extracted to construct (Parm 4-2-3).

Yes. Putting together the Result result from 3, each IE of 4-2 message of Table 4 by the above process is as follows.

(Parm 4-2-3) eNodeB2 {DL (CC1, CC2, CC3), UL (CC5)}

(Parm 4-2-4) eNodeB2 {ULGQ 40 (= 10 + 8 + 22), DLGQ 30}

(Parm 4-2-5) eNodeB2 (DLCCGQcc1 10, DLCCGQcc2 8, DLCCGQcc3 22, ULCCGQcc5 30)

142 of FIG. 14B is a flowchart for describing a process of triggering Advanced Resource Preparation.

The "serving (source) [CMC]" state 1400 means the state of the eNodeB 1 in the scenario (UE1 location 1110) of FIG. 11 and the automatic resource reservation step of FIG.

In step 1411, the serving base station (eNodeB 1) collects the measurement data using the RRC and CSAP.

 When the serving base station (eNodeB 1) generates an A4-1 event based on the collected data, the serving base station (eNodeB 1) sends a handover request to the neighboring base station that caused A4-1. At this time, the handover request requests Advanced Resource Preparation.

In step 1421, the neighbor base station transmits a handover request request to the serving base station eNodeB 1 and performs advanced resource preparation.

In step 1422, the neighbor base station stores or updates information included in the handover request (eg, handover CC candidate group information, Parm 4-2-1-5 in Table 4-2).

<Resource Release of 1280 in the automatic resource cancellation step of Figure 12>

(UE1 1130 position in FIG. 11, 132 flow in FIG. 13B, 142 flow in FIG. 14B)

According to the scenario of FIG. 11, when UE1 is at location 1130, an A4-2 event may occur for any CC of eNodeB 1. Referring to the automatic resource cancellation step of FIG. 12, since the handover decision and execution of FIG. 12 are performed at the location 1120 of UE1 according to the scenario of FIG. 11, the serving base station is eNodeB 2 and the neighbor base station is eNodeB 1.

Therefore, in operation 1270, the measurement value for determining the A4-2 event or the A4-2 event for the eNodeB 1 is transmitted to the serving base station (eNodeB 2) through a Measurement Report, which is an RRC protocol message. That is, the measurement report is delivered to the D-RRM CMC of the serving base station (eNodeB 2).

In step 1275, the serving base station (eNodeB 2) sends a UE Context Release, which is an X2AP protocol message, to the neighbor base station (eNodeB 1) that caused A4-2.

In step 1280, the neighbor base station (eNodeB 1) performs a resource release. Internal information of UE Context Release, which is an X2AP protocol message, includes (Parm 4-3-1) and / or (Parm 4-3-2) information of [Table 4].

In the scenario of FIG. 11, in the process of processing Advanced HO Preparation (1215 of FIG. 12), or in the process of Prompt Resource Preparation (1240 of FIG. 12), the eNodeB 2, which is a neighboring base station, receives a handover request (1215, 1235). ) Save (Parm 4-1-6) and (Parm 4-1-1) in [Table 4]. Therefore, the current serving base station (eNodeB 2) can send the relevant information to the base station (eNodeB 1) that caused the A4-2 event, at which time the relevant information is stored in the serving base station (eNodeB 2).

The process after receiving the UE Context Release message is the same as 132 of FIG. 13B. The UE Context Release message is received in the "Neighbor (Target) [CMC]" state of the CMC, and releases resources for the UE.

The flow 142 of FIG. 14B also shows a process in which a UE context release is triggered.

In 142 of FIG. 14B, the "serving (source) [CMC]" state refers to a state in which UE1 of FIG. 11 is located at position 1130 and a state of eNodeB 2 in the automatic resource cancellation step of FIG. 12.

In step 1411, the serving base station (eNodeB 2) collects the measurement data using the RRC and CSAP.

In step 1423, the serving base station (eNodeB 2) performs advanced HO preparation or determines UE context release based on the collected data.

In step 1424, when the A4-2 event occurs by determining the UE context release, the serving base station (eNodeB 2) may send a UE Context Release (Resource Release) to the neighbor base station that caused A4-2.

<Handover Decision and Execution Step of FIG. 12>

(UE1 1120 position in FIG. 11, flow 133 in FIG. 13C, flow 141 in FIG. 14A)

An example in which DL CCs used by eNodeB 1 are CC1, CC2 and CC3 while UE1 shown in FIG. 11 is located at position 1120 and CCs that are full coverage CC2 and CC3 is taken as an example.

In step 1230, if a CC having an RS larger than a measurement value of a reference signal (RS) of the serving base station (eNodeB 1) exists in the neighboring base station (eNodeB 2), that is, when an A3-1 event occurs, the serving base station (eNodeB) A handover decision of 1230 of FIG. 12 is made. The measurement value of the RS (Reference Signal) of the serving base station is DLENBCCSNR _{UE1CC1eNodeB1} or DLENBCCSNR _{UE1CC1eNodeB1} .

In general, in step 1220, the serving base station (eNodeB 1) receives the X2AP message for the base station that caused the A3-1 (step 1220), and the information of (Parm 4-2-1-5) in Table 4 below. Save it.

Therefore, if a handover is determined to the neighbor base station (eNodeB 2) in step 1230, the serving base station (eNodeB 1) delivers a handover RRC ConnectionReconfiguration message to the UE in step 1250.

However, in step 1230, the handover to the neighbor base station (eNodeB 2) is determined, but information of (Parm 4-2-1 to 5) for the neighbor base station (eNodeB 2) is stored in the serving base station (eNodeB 1) It may not be. In this case, in step 1235, the serving base station (eNodeB 1) transmits a handover request to the neighbor base station (eNodeB 2).

In step 1240, the neighbor base station (eNodeB 2) performs a Prompt Resource Preparation to obtain information. Operation 1240 is the same as operation 1215 and operation 131 of FIG. 13A.

That is, after the handover decision is made, if there is information of (Parm4-2-1 to 5) about the neighbor base station (eNodeB 2), the serving base station (eNodeB 1) informs the UE of the RRC ConnectionReconfiguration (step 1250) for handover. Send it right away. On the other hand, if there is no information of (Parm4-2-1-5), the serving base station (eNodeB 1) and the neighboring base station (eNodeB 2) performs the process shown in the dotted line of FIG.

In step 1245, if the handover request message received from the neighbor base station (eNodeB 2) is successful, in step 1250, the serving base station (eNodeB 1) sends an RRC ConnectionReconfiguration for handover to the UE.

In step 1255, the UE reconfigures the UE by using the information included in the received RRC ConnectionReconfiguration, and sends an RRC message such as RRC Connection Reconfiguration Complete to the target base station (eNodeB 2).

In step 1260 and 1265, the target base station (eNodeB 2) transmits and receives a procedure (Path Switch Request, Path Swtich Requst Ack) for changing the data path defined in the S1AP protocol message with the aGW or MME. This ends the handover.

Hereinafter, the handover determination and execution steps of FIG. 12 will be collectively described from each base station eNodeB 1 and eNodeB 2 with reference to the UE1 located at the location 1120.

14A and 14A are diagrams for explaining the handover determination and execution steps of FIG. 12 from the perspective of the source base station.

The “Serving (Source) [CMC]” state is the state of eNodeB 1 shown in FIG. 12 when UE1 is in position 1120 of FIG. 11. At this point, the eNodeB 1 operates as a source base station and collects measurement data using RRC and CSAP. The source base station (eNodeB 1) divides the data into the following two steps based on the collected data and performs a handover decision as shown in 1230 of FIG.

The first step is to determine the handover based on radio quality (eg, ULCCQ of Table 2 for UL, DLENBCCSNR of Table 3 for DL) based on radio quality.

The second step is to determine based on history whether the handover decision made in the first step is unnecessary. The second step is optional.

When the Inter-eNodeB handover is determined by the above two steps, the serving base station (eNodeB 1) transmits an RRC ConnectionReconfiguration 1415 for the handover to the UE, and transitions to the "neighbor (target) base station" state.

However, if it is not an Inter-eNodeB handover, the serving base station eNodeB1 remains in the "serving (source) base station" state. In this process, if there is no information of (Parm 4-2-1 to 5) of the target base station for which the first step handover is determined, the source base station eNodeB 1 receives the message of step 1418 for the Prompt Resource Preparation 1240 (FIG. 1235 of 12) is sent to the target base station, and a message of step 1419, which is a response thereto, is received from the target base station to obtain (Parm 4-2-1 to 5) information on the target base station.

In the handover decision of 141 illustrated in FIG. 14A, a traffic load indication (TLI) and an interference coordination indication (ICI) indication may be generated from a CMC or a TLC of a D-RRRM of the same base station. TLI and ICI are requests for neighboring base stations to exclude the use of a particular CC in a CA environment, and the stored information about neighboring base stations (Parm 4-2-3, 4-2-4, 4-2). Compared with -5), if there is a specific CC, information can be updated through message exchange in steps 1418 and 1419.

13C is a flowchart for explaining the handover determination and execution steps of FIG. 12 from the perspective of a neighbor (target) base station.

The “Neighbor (Target) [CMC]” state is where UE1 is at location 1120 and is the state of the neighbor base station (eNodeB 2) of FIG. 12. In step 1331, the neighbor base station (eNodeB 2) receives an RRC ConnectionReconfigurationComplete (for HO) from the UE.

In step 1332, the neighbor base station (eNodeB 2) sends a Path Switch Request (which corresponds to step 1265 in FIG. 12), which is an S1AP message, to the MME and waits for a Path Switch Reqeust Ack.

In step 1333, when the Path Switch Reqeust Ack is received from the MME, in step 1340, the neighbor base station eNodeB 2 becomes a serving base station and becomes a "serving (source) [CMC]" state.

141 First Phase of FIG. 14A

Hereinafter, operation 141 of FIG. 14A will be described in detail.

In operation 1411, the UE may measure an SNR quality (DLENBCCSNR of Table 3) for a CC-specific reference signal operated by neighboring base stations and generate an A3-1 event from the measurement result.

The A3-1 event is used by UE1 when one of the results of measuring the DLENBCCSNR for the CCs of neighboring base stations is UCcc (Used Carrier CC of the current source base station, for example, the serving base station of the current UE1 is eNodeB 1). This means that the CC information, that is, larger than the DLENBCCSNR measurement value of each CC corresponding to (Parm 4-1-5)). UCcc is the set of CCs currently being used by the user equipment (UE), and BCcc is the best set of best CCs for the current user equipment (UE).

In operation 1225 of FIG. 12, the user equipment UE reports the A3-1 event, which is a measurement result, to the serving base station eNodeB 1 in the form of a measurement report message. Alternatively, the A3-1 event may be determined by the D-RRM CMC of the serving base station eNodeB 1 based on the information in the message (step 1225) in the form of a periodic measurement report. In operation 1230, the serving base station eNodeB 1 may review the best CC set based on the measurement report message. The result of this review is sorted in order of the magnitude of the currently measured value, and the CC having the largest DLENBCCSNR may be determined as the CC of the base station.

Referring back to '141' in FIG. 14A, in step 1412, which is the first phase, the best CC set is determined in order of the magnitude of the measurements of DLENBCCSNR, and UCcc and BCcc are inter-eNodeBs (i.e., other neighbors than the current serving base station). If BCcc is determined as the base station), the handover type described with reference to 821, 822, and 831 of FIG. 8 is determined. The fact that UCcc and BCcc are inter-eNodeBs means that BCcc is determined as another neighbor base station instead of the current serving base station.

The determination of BCcc is determined by the information of the message (step 4-2 of Table 4) of the message of steps 1215 and 1240 of FIG. 12 and steps 1220 and 1245 from the processing of the neighboring base station. That is, in the case of inter-eNodeB, BCcc is determined by the neighbor base station. The BCcc determination method (ie, (Parm 4-2-3)) is described in the Advanced Resource Preparation process, and is identical to the Prompt Resource Preparation process.

<141 Second Phase of FIG. 14A>

If BCcc determined at 1412 means inter-eNodeB handover, it is dependent on the DLENBCCSNR measurement and thus does not reduce unnecessary handovers such as ping pong. Therefore, step 1413, which is a second phase, may be additionally performed.

In step 1413, the serving base station eNodeB1 determines whether or not inter-eNodeB handover to BCcc determined in step 1411 is unnecessary by using the accumulated history information.

According to an embodiment of the present invention, when handover is performed between base stations while UE1 is connected to a network, the CMC of the D-RRM of each base station accumulates history information. The CMC of the D-RRM may identify the movement pattern of the UE1 by using the accumulated history information, and secondly verify whether the handover to the target base station is suitable according to the identified movement pattern.

FIG. 15 is a view for explaining a history information storing method for use in step 1413 of FIG. 14A.

If the normal handover is made according to the movement path of the UE illustrated in FIG. 15, history information as shown in [Table 5] is generated.

index 0 One 2 3 CA ID 413 488 414 415 CA ID 313 None 314 315 Cell type
(BD1) Medium (413) Medium (488) Medium (414) Medium (415) Cell type
(BD3) Medium (313) None Medium (314) Medium (315) UE stays in eNodeB 4095 (sec) 350 (sec) 120 (sec) Recording DLENBCCSNR on Inter-eNodeB Handover
Set (optional) [413] [488], [313], [388] DL SNR set [488] [414], [388], [314] DL SNR set [414] [415], [314], [315] DL SNR set

Referring to [Table 5], the stored history information includes CA ID, Cell Type, time spent by the UE in the eNodeB, and signal quality measured when the handover decision was made (ie, DLENBCCSNR of the source CA-ID and the target base station CA-ID. DLENBCCSNR information).

The CA ID distinguishes between the base station and the FB used by the base station. The CA ID is also used to make the divided FB into a globally unique value. When the CA ID has downlink frequency bands FB1 and FD3 as shown in FIG. 2 and cell planning is performed for each base station eNodeB, each base station has a cell including FB1 and FB3.

Meanings included in the CA ID are expressed separately, and the separated meanings may be separately included in the history information. For example, the CA ID may be divided into an eNodeB ID, an FB ID, and a CELL ID, and recorded in history information. [Table 5] shows an example of history information for each CA ID.

That is, if a normal handover is performed according to the UE movement path in FIG. 15, the UE moves to another serving base station with a CA ID used by the previous serving base station, a cell type corresponding to the CA ID, a time spent in the previous serving base station, and the like. The DLENBCCSNR value at the time of determination is stored in the CMC of the D-RRM of the base station. The DLENBCCSNR value may include a DLENBCCSNR value of the serving base station and a DLENBCCSNR value of the target base station.

In Table 5, the cell type is divided into large, medium, and small, and more specifically, it may be subdivided. In addition, the time spent by the UE in the CA may be represented by, for example, an integer greater than or equal to zero, and may be set and recorded as the maximum value when the stay time exceeds the set maximum value.

Whenever a handover occurs, the history information as shown in [Table 5] moves from the previous serving base station before the handover to the serving base station after the handover. Therefore, the current serving base station has history information as shown in [Table 5].

If the current serving base station determines the inter-eNodeB handover in step 1412, in step 1413, the serving base station determines whether the inter-eNodeB handover is correct by using history information stored in the serving base station. .

When the inter-eNodeB handover from UCcc to BCcc is determined, the serving base station (A) analyzes the frequency, continuity and temporality of the pattern from the stored history information based on the determined information, and performs itner-eNodeB handover to the pattern. Can decide whether or not to

The pattern is information determined in the above-described First Phase, that is, UCcc → BCcc, and the frequency is the number of times this pattern has occurred in the history. Continuity is that the pattern is repeated continuously (e.g. eNodeB1 (DL-CC1, CC3) → eNodeB 2 (DL-CC3) → eNodeB1 (DL-CC1, CC3) → eNodeB 2 (DL-CC3)). The temporality is used to determine how many minutes the pattern is generated based on the present time. The temporality may be divided into old information, intermediate information or immediately previous information.

Priority and combination methods for frequency, continuity, and temporal application to determine whether to handover decisions to a pattern can be adjusted according to the system operating situation. Optionally, the DLENBCCSNR set to be recorded may additionally be used. For example, the algorithm may be designed such that the currently measured DLENBCCSNRs calculate a difference from the DLENBCCSNR measurements on history, and exclude or further consider the DLENBCCSNR set according to the calculation result.

<First Phase in FIGS. 14A, 141>

When the BCcc set determined at 141 of FIG. 14A includes an inter-eNodeB, an embodiment of the present invention may be described using A3-1, A3-1 ', and Rn events.

A3-1 denotes a case where DLENBCSNR qualities of neighboring base stations become higher than DLENBCCSNR qualities corresponding to UCcc of the serving base station, as shown in FIG. 9. A3-1 'is an event meaning that system operating parameters, hysteresis or time-to-trigger, are not applied to A3-1.

For example, A3-1 manages mobility for the UE, and is an event that, if there is hysteresis or time-to-trigger, can handover faster or delay by handover value. That is, A3-1 means that the measured value to which hysteresis or time-to-trigger is applied is performed in step 1412. A3-1 'means hysteresis = 0 and time-to-trigger = 0, so purely measured value This means performing step 1412.

Description of Rn is as follows.

C _{HO (SS)}

= {{ c _{HO (SS) 1 -CC 1, eNodeB 2} , c _{HO (SS) 2 -CC 1 , eNodeB 3} } , { c _{HO (SS) 3 -CC 2, eNodeB 2 ,. },… }}

C _{HO (RE)}

= {{ c _{HO (RE) 1-CC1, eNodeB2} , c _{HO (RE) 2-CC1eNodeB3} }, {c _{HO (RE) 3-CC2, eNodeB2,... },… }}

P _HO = {{ p _{HO1-CC1, eNodeB1} , p _{HO2-CC1, eNodeB3} }, {p _{HO3-CC2, eNodeB2,... },… }}

R _HO = { R _{HO (RES) -eNodeB2} , R _{HO (RES) -eNodeB3} }

R _{HO (RES) -eNodeB2 =} { CC ₁ }. R _{HO (RES) -eNodeB23 =} { CC _1, CC2 }

C _{HO (SS)} is to list the quality measured for DLENBCCSNR of neighboring base stations in large order by CC.

The C _{HO (RE)} is a difference between the quality measured for the DLENBCCSNR of the neighboring base station and the previously measured quality, and is listed by CC in the order of the large difference.

The P _HO lists neighboring base stations having CCs larger than the reference value Thc through which the DLENBCCSNRs of the neighboring base stations can communicate, in order of DLENBCCSNRs, in the order of increasing CC.

R _HO means that 1220 and 1240 shown in FIG. 12 have received information about 1220 and 1240 (4-2 information in Table 4), respectively, and that (Parm 4-2-2) was SUCESS. For example, R _{HO (RES) -eNodeB2 =} { CC ₃ } means that when the Advanced Resource Preparation or Prompt Resource Preparation from eNodeB1 to eNodeB2 is allowed to use CC3 of eNodeB2. In addition, R _{HO (RES) -eNodeB3 =} { CC _1, CC2 } means that when the Advanced Resource Preparation or Prompt Resource Preparation is performed from eNodeB1 to eNodeB3, CC1 and CC2 of eNodeB3 are authorized.

Events that occur when the order of C _{HO (SS)} , C _{HO (RE)} and P _HO are changed are defined as R1, R2, and R3, respectively.

A method for inter eNodeB handover in a wireless mobile communication system using Carrier Aggregation using the above information will be briefly described as follows.

R_HO 인 경우, 서빙 기지국은 도 12의 1235단계 내지 1245단계에 의해 Prompt Resource Preparation을 수행할 수 있다. The serving base station to which the user equipment (UE) is connected determines BCcc only in the order of the measured values of DLENBCCSNR, and the determined BCcc means inter-eNodeB, and BCcc

In the case of R _HO , the serving base station may perform prompt resource preparation in steps 1235 to 1245 of FIG. 12.

R_HO 인 경우가 있으면, 이는 TLC가 부하관리를 위하여, 핸드오버 자원 준비를 위해 예약된 자원을 강제해제시키는 경우에 발생할 수 있다.If (Parm 4-2-2) of the message sent by the neighboring base station is Success, the serving base station updates the BCcc set with (Parm 4-2-3). BCcc even if Advanced Resource Preparation is performed in the present invention

R_HO If this is the case, this may occur when the TLC forces a resource released for handover resource preparation for load management.

Meanwhile, a case in which a preparation process (Advanced Resource Preparation or Prompt Resource Preparation) shown in FIG. 12 is performed, that is, BCcc ∈ R _HO is described below.

If the serving base station to which the user equipment (UE) is connected determines only in the order of the measured value of DLENBCCSNR, the determined BCcc means inter-eNodeB, and if (Parm 4-2-3) to the corresponding target base station is ready, The handover may be executed or the prompt resource preparation according to steps 1235 to 1245 may be performed again. In this case, when the prepared (Parm 4-2-3) is not used, the DLENBCCSNR signal quality for the stored CC determined by (Parm 4-2-3) may be relatively low.

16 to 18 are flowcharts illustrating the process 1412 of FIG. 14A in more detail.

16 and 18 are flowcharts illustrating a method of executing inter-eNodeB handover using the signal strength required for requesting the RRC connection reconfiguration described above when the BCcc set is determined at the serving base station. The hysteresis information update referred to in FIGS. 16 to 18 will be described later.

In step 100, the serving (source) base station may determine a BCcc set to be used by the user equipment (UE).

In step 110, when the BCcc set determined in step 100 is an inter eNodeB, the serving (source) base station may generate an event Rn.

In step 120, if Rn is R2, in step 130, the serving (source) base station may update the hysteresis information as shown in Table 6 with respect to the DLENBCCSNR of the base station.

In step 140, the serving (source) base station 100 may reconsider and update the BCcc set by applying the updated hysteresis information 130.

If the BCcc to be used by the UE is found in the updated BCcc set in step 150, in step 160, the serving (source) base station may determine whether the found BCcc has changed compared to the previous BCcc set.

If not changed, step 100 may be waited for the event to occur.

On the other hand, if it is determined that the change in step 160, in step 170, the serving (source) base station determines whether the changed BCcc is included in the R _HO .

If it is not included in the determination result, in step 180, after performing the prompt resource preparation (steps 945 to 955 of FIG. 9), it may enter the BCcc Found state of step 100 and wait for the next event.

If the prompt preparation of step 180 fails, in step 190, the serving (source) base station 100 may enter a no BCcc found state.

On the other hand, if the determination result of step 170 is included in the R _HO , it may enter the BCcc Found state of step 100 may wait for the next event.

On the other hand, when the new history information and the time-to-trigger is applied in step 210 and the A3-1 event occurs, in step 220, the serving (source) base station may update the BCcc.

If it is determined in step 230 that the updated BCcc is changed, and in step 240, the changed BCcc is not included in the R _HO , in step 250, prompt resource preparation (steps 945 to 955 of FIG. 9) may be performed. .

If the prompt resource preparation succeeds, in step 260, 1250 of FIG. 12 may be sent to the UE.

On the other hand, if the BCcc is not changed as a result of the determination of step 230, the process may enter the BCcc Found state of step 100 and wait for the next event.

In addition, in step 240, if the changed BCcc is included in the R _HO , in step 270, the process of prompt resource preparation (steps 1235 to 1245 of FIG. 9) may be omitted, and 1250 of FIG. 12 may be sent to the UE.

In operation 310 of FIG. 17, when an A3-1 ′ event that does not apply a new hysteresis and time-to-trigger occurs 310, in step 320, the serving (source) base station may update BCcc.

In step 330, it is determined that the updated BCcc is changed, and in step 340, if the changed BCcc is equal to P _HO 1 of the same serving (source) base station, preparation according to whether the R _HO belongs (steps 1235 to 1245 of FIG. 12). ) Can be performed. That is, if it is determined in step 340 that the same as each other, the serving (source) base station may perform steps 240 to 270.

In addition, in step 340, if the changed BCcc is different from P _HO 1 of the same serving (source) base station, in step 350, hysteresis information may be updated. In other words, BCcc may be updated by applying modified hysteresis.

In addition, if it is determined in step 340 to be different from each other, in step 350, the serving (source) base station may perform step 240.

18 is a flowchart illustrating a method of executing an inter eNodeB call using the signal strength required to request the RRC connection reconfiguration as described above when the BCcc set is not determined at the source base station.

In step 400, when the BCcc set is not determined in the serving (source) base station and is in the No BCcc Found state, in step 410, the serving (source) base station may generate an event Rn.

If Rn is R2 in step 420, in step 430, the serving (source) base station may update hysteresis information as shown in [Table 6].

In step 440, the serving (source) base station may update the BCcc set by applying the updated hysteresis information.

If the BCcc to be used by the user equipment (UE) is found in the updated BCcc set in step 450, in step 460, the source base station 100 determines whether the found BCcc is included in the R _HO .

If the determination result is included in the R _HO , in step 470, the found BCcc is updated, and in step 480, the BCcc found state may be entered.

On the other hand, if it is not included in the determination result in step 460, in step 490, if successful by performing the prompt preparation (steps 1235 to 1245 of Figure 12), it may enter to step 470. If the prompt resource preparation of step 490 fails, the process proceeds to step 400 and may wait for an Rn or A3-1 'event in the No BCcc found state.

On the other hand, if the A3-1 'event occurs in step 510, the hysteresis information is updated as shown in [Table 6] in step 520, and may enter step 400.

<Hysteresis information update mentioned in FIGS. 16 to 18>

The hysteresis information update of Figs. 16 to 18 is applied as follows.

First, the amount of change is pre-defined as LARGE, MEDIUM, and SMALL according to the degree of change (CHO (RE)) of DLENBCCSNR for each base station and CC. It also pre-defines the minimum and maximum values of applicable hysteresis as LARGE, MEDIUM and SMALL. This leads to a handover toward the CC where the CHO (RE)) change becomes larger than the CC where the largest DLENBCCSNR is currently selected, and conversely to cause the handover to be delayed toward the CC that becomes smaller CHO (RE)). For sake. Classification of these values requires system-specific tuning.

For example, CHO (RE) LARGE is defined as 20 or more, MEDIMUM is 19 ~ 10, SMALL is 9 or less, hysteresis LARGE is 10 or more, MEDIMUM 9 ~ 5, SMALL is 5 or less. In addition, "delta hysteresis" is defined as 2.

The radio quality (i.e., DLENBCCSNR) for the CC1 of the neighboring base station was previously 10, now 15, the radio quality for CC2 was previously 5, now 18, and the radio quality for CC3 was previously 3, now 50 It is assumed that the hysteresis being applied to each of CC1, CC2, and CC3 is 11, 3, and 8, respectively.

At this time, CHO (RE) CC1, CHO (RE) CC2, and CHO (RE) CC3 are 5, 13, and 47, respectively. If this is defined as the above prescribed class, it becomes SMALL, MEDIMUM, and LARGE, respectively.

For CC1, since CHO (RE) is SMALL and the current hysteresis is LARGE to 11, the current hysteresis is INCREASE as much as delta hysteresis. Therefore, according to [Table 6], the new hysteresis is 13.

For CC2, since CHO (RE) is MEDIMUM and the current hysteresis is SMALL at 3, the current hysteresis is maintained as much as delta hysteresis. Thus, according to Table 6, the new hysteresis is 3, which is the previous hysteresis.

In addition, for CC3, since CHO (RE) is LARGE and the current hysteresis is 8 and MEDIMUM, the current hysteresis is DECREASE as much as the delta hysteresis. Therefore, according to Table 6, the new hysteresis is six.

IF
c _{HO (RE) i} AND
Current Hysteresis is THEN
Hysteresis is LARGE LARGE DECREASE LARGE MEDIUM DECREASE LARGE SMALL DECREASE MEDIUM LARGE MAINTAIN MEDIUM MEDIUM MAINTAIN MEDIUM SMALL MAINTAIN SMALL LARGE INCREASE SMALL MEDIUM INCREASE SMALL SMALL INCREASE

The method according to the present invention can be implemented in the form of program instructions that can be executed by various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. The medium may be a transmission medium such as an optical or metal line, a wave guide, or the like, including a carrier wave for transmitting a signal designating a program command, a data structure, or the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

Claims (1)

In a wireless mobile communication system using Carrier Aggregation, a method for handover between base stations,
Receiving and storing measurement information about neighboring base stations located around the serving base station;
Analyzing the measurement information on the received neighbor base stations to determine resources of neighbor base stations having a downlink quality greater than a reference value as a candidate group;
Reserving a resource of a neighbor base station having the largest downlink quality among the candidate groups as a resource for handover of the user terminal;
Performing a handover of the user terminal to the neighbor base station having the highest downlink quality through the reserved resource; and
Canceling the reserved resource if the downlink quality of the reserved resource is less than the reference value
Method for handover between base stations comprising a.

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