KR100931727B1 - Adaptive handoff parameter control method and apparatus - Google Patents

Abstract

The present invention relates to a handover parameter control method in a WCDMA system. Handover parameter control method in a wireless network controller according to the present invention comprises the steps of transmitting a signaling handover parameter corresponding to a specific cell to the base station using a System Information Update Message (System Information Update Message); And setting an SRB upon receiving a call setup request signal from the mobile terminal, and transmitting a traffic handover parameter to the mobile terminal using a radio bearer setup message through the set signaling radio bearer (SRB). The base station transmits the signaling handover parameter using a broadcast channel of a corresponding cell. Accordingly, the present invention has an advantage of providing a mobile communication system capable of managing radio resources more efficiently and improving call success rate by differently setting handover parameters in signaling state and traffic state.

Handover, parameter, SRB, RB, signaling, traffic

Description

Adaptive handoff parameter control method and apparatus {Method and Apparatus for Controlling Adaptive Handoff Parameter}

The present invention relates to a handoff in a mobile communication system, and more particularly, an adaptive handoff parameter control method capable of adaptively controlling handoff parameters in consideration of a channel setting state of a mobile terminal in a WCDMA system. And to the apparatus.

Wideband Code Division Multiple Access (WCDMA) communication is a third generation asynchronous wireless access technology recommended by International Mobile Telecommunication (IMT-2000), which is suitable for high-speed data transmission and can provide very high call quality.

Such a WCDMA system provides a seamless service for a mobile terminal moving at a high speed, and provides a mobility management function to maintain a certain level of service quality.

A representative example of the mobility management function is a handover, and the WCDMA system provides various handover procedures according to the mobility characteristics of the mobile terminal.

In other words, the handover refers to a technology that changes the existing call path and establishes a new call path between the mobile terminal and the base station so that the call can be continuously maintained even if the mobile terminal leaves the sector service area within the base station currently being serviced. .

For example, a WCDMA system can provide soft handover to ensure inter-cell mobility, soft handover to ensure inter-base station mobility, and hard handover to ensure mobility between heterogeneous frequency or heterogeneous radio access technologies. have.

In general, a handover is performed by a mobile station when a mobile station measures a reference signal received from at least one base station, for example, a pilot signal, and transmits a measurement result to a base station controller through a base station. It may be performed through a series of procedures for determining whether to hand over based on the measurement result and transmitting the determination result to the corresponding mobile terminal.

In particular, the base station controller may provide the mobile terminal with measurement parameters related to handover, hereinafter referred to as 'hand over parameters', over a predetermined control channel.

For example, in WCDMA, a broadcast is mapped and transmitted to a primary common control physical channel (PCCPCH) according to a connection state of a mobile terminal, where the connection state includes an idle state and a connected state. Signaling radio bearer created through a channel (BCH) and a radio resource control (RRC) connection setup procedure (hereinafter referred to as a 'signaling radio bearer'). Parameters can be provided to the mobile terminal.

More specifically, the WCDMA system may transmit the handover parameter to the mobile terminal through a specific system information block (SIB) included in the BCH and a measurement control message transmitted through the SRB. .

The mobile terminal measures the pilot signal received from the base station using the received handover parameter, for example, a common pilot channel (CPICH) of WCDMA, and measures the measurement result through a predetermined control signal. Transmit to base station controller.

The WCDMA system uses an SRB for transmitting and receiving control signals related to call setup, security, authentication, and the like between a mobile terminal and the system, and a radio bearer (RB) for transmitting actual user data according to a call processing procedure defined in the standard. Set it.

In particular, the conventional handover parameters in the state in which the SRB is set up (hereinafter referred to as 'RRC connection establishment state') and in the traffic state in which both the SRB and RB are set up are equally applied.

However, since the RRC connection configuration state and traffic state have different characteristics and purposes, it is preferable that different handover parameters are applied.

For example, since the handover in the RRC connection setup state directly affects the call success rate, it is desirable to set the hand over parameter so that the handover can be performed to the optimal cell as soon as possible.

On the other hand, in the traffic state, it is desirable to set the handover parameter so that a relatively small number of handovers occur rather than the RRC connection setting state in consideration of system load and resource utilization efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide an adaptive handover parameter setting method capable of adaptively setting different handover parameters according to a bearer setting state of a mobile terminal in a WCDMA system. .

Another object of the present invention is to provide an adaptive handover parameter setting apparatus capable of improving call success rate and resource utilization efficiency by setting a handover parameter suitable for a bearer setting state of a mobile terminal.

Another object of the present invention is to provide an adaptive handover parameter setting method and apparatus capable of automatically updating an optimized handover parameter for each bearer setting state by using statistical information collected for each cell.

Other objects of the present invention will be readily understood through the following description of the embodiments.

According to an embodiment of the present invention, a method of controlling a handover parameter in a wireless network controller of a wideband code division multiple access (WCDMA) system is disclosed.

A method of controlling a handover parameter in a wireless network controller according to an embodiment of the present invention includes transmitting a signaling handover parameter corresponding to a specific cell to a base station using a system information update message; And setting an SRB upon receiving a call setup request signal from the mobile terminal, and transmitting a traffic handover parameter to the mobile terminal using a radio bearer setup message through the set signaling radio bearer (SRB). The base station transmits the signaling handover parameter using a broadcast channel of a corresponding cell.

According to another embodiment of the present invention, a method of controlling a handover parameter in a device connected to a wireless network controller of a wideband code division multiple access (WCDMA) system is disclosed.

A method for controlling a handover parameter in a device connected to a wireless network controller includes: generating call processing statistics information using call processing related messages received from the wireless network controller; An event generation step of determining whether to update a handover parameter for each cell by using the generated call processing statistics information and generating a predetermined event according to the determination result; A handover parameter updating step of updating an optimized handover parameter according to the generated event; And an update parameter transmission step of transmitting a predetermined handover parameter update message including the updated handover parameter to the radio network controller.

According to another embodiment of the present invention, an apparatus for controlling a handover parameter is provided connected to a wireless network controller of a wideband code division multiple access (WCDMA) system.

A handover parameter control device connected to a wireless network controller according to an embodiment of the present invention analyzes call processing related messages received from the wireless network controller, generates call processing statistics information, and includes an updated handover parameter. A control unit for generating a message and transmitting the message to the wireless network controller; An event generator configured to determine whether to update a handover parameter by using the generated call processing statistics information and to generate an event according to the determination result; And a handover parameter generator configured to generate an optimized handover parameter according to the generated event and transmit the generated handover parameter to the controller.

The present invention has the advantage of providing an adaptive handover parameter setting method capable of adaptively setting different handover parameters according to the bearer setting state of the mobile terminal in the WCDMA system.

In addition, the base station controller according to the present invention has an effect of improving the call success rate and resource utilization efficiency by setting the appropriate handover parameter according to the bearer setup state of the mobile terminal.

The present invention also provides an adaptive handover parameter setting method and apparatus capable of automatically updating an optimized handover parameter for each bearer setting state using statistical information collected for each cell.

In addition, the present invention by differentially setting the handover parameters in the RRC connection configuration state and traffic state, there is an effect that can prevent the occurrence of excessive handover in the traffic state.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The term and / or includes a combination of a plurality of related items or any item of a plurality of related items. The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this application, the terms "comprising" or "mounted" and "mounted" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, one Or other features or numbers, steps, operations, components, parts or combinations thereof in any way should not be excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and are not construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Other aspects, features, and advantages other than those described above will become apparent from the following drawings, claims, and detailed description of the invention.

Hereinafter, a preferred embodiment of an adaptive handoff parameter control method and apparatus in a WCDMA system according to the present invention will be described in detail with reference to the drawings.

1 is a block diagram of a mobile communication network according to an embodiment of the present invention.

As shown in FIG. 1, a mobile communication network according to an embodiment of the present invention is largely composed of a universal terrestrial radio access network (UTRAN) 150 and a core network composed of a UE 100, a NodeB 120, and an RNC 130. Network: CN, 140) may be included.

In the 3GPP standard, a mobile terminal is called a user equipment (UE), and a general base station is defined and used as a NodeB.

In the following description, for convenience of description, the UE 110 and the NodeB 120 will be referred to as the mobile terminal 110 and the base station 120, respectively, and the RNC 130 will be referred to as the radio network controller 130. do.

The mobile terminal 110 according to the present invention preferably supports Wideband Code Division Multiple Access (WCDMA), which is a third generation mobile communication scheme.

In particular, the mobile terminal 110 according to the present invention receives the handover parameter from the base station 120, measures the radio signal transmitted from the adjacent base station 120 using the received handover parameter, and the measurement result is the base station Transmit to 120. Here, the handover parameter may be set to a different value for each bearer setting state of the mobile terminal 110.

The bearer setup state according to the present invention is a radio resource control (RRC) connection setup state in which only a signaling radio bearer (SRB) is established, and a radio bearer (RB) that is a bearer for transmitting SRB and actual user data. ) May be classified into a set traffic state (In Traffic State).

In the following description, the handover parameters used in the RRC connection configuration state and the traffic state will be referred to as 'signaling handover parameters' and 'traffic handover parameters', respectively.

The mobile terminal 110 may obtain the signaling handover parameter by decoding a primary common control physical channel (PCCPCH) for transmitting broadcast channel information in an idle state.

From the perspective of the base station 120, the base station 120 receives a signaling handover parameter from the radio network controller 130 through a system information update message, and transmits the received signaling handover parameter to the PCCPCH. Map and broadcast to the whole cell.

On the other hand, the mobile terminal 110 may receive the traffic handover parameter through the SRB preset in the connected state.

Here, the traffic handover parameter may be received through a radio bearer setup message or a measurement control message.

According to an exemplary embodiment of the present invention, the mobile terminal 110 may first receive the traffic handover parameter received through the radio bearer setup message and then receive the changed traffic handover parameter through the measurement control message. All.

Base station 120 may be composed of a plurality of cells (Cell), each cell is a common channel (Common Channel) through a pilot signal-for example, Common Pilot Channel (CPICH) in WCDMA-and system information A broadcast channel, for example, a Primary Common Control Physical Channel (PCCPCH) in WCDMA, is transmitted to the entire cell.

Here, the mobile terminal 110 may receive the pilot signal and obtain reference phase information of all common channels transmitted from the corresponding cell.

Thereafter, the mobile terminal 110 may decode the broadcast channel using the obtained reference phase information. Here, the broadcast channel may include various system information for controlling the operation of the mobile terminal 110.

For example, WCDMA is a plurality of system information blocks (hereinafter, referred to as 'SIBs'), which are scheduled according to the characteristics and purposes of the system information, where each SIB is composed of system information of similar attributes. Transmits by mapping-to PCCPCH.

For example, dynamic system information elements that are variable over time may be included in a different SIB than static system information elements that rarely change in the system.

In addition, the WCDMA is referred to as a master information block (hereinafter referred to as 'MIB (Master Information Block)') and scheduling block (hereinafter referred to as 'SB (Scheduling Block)') to provide scheduling information of the SIB to the mobile terminal 110. ) May be included in the system information.

Here, the MIB may include a reference field for indicating the presence of a specific SIB and scheduling information of a number of system information blocks in a cell.

In addition, the MIB may include scheduling information and reference fields corresponding to one or two SBs that provide scheduling information and reference fields for all additional SIBs.

That is, the mobile terminal 110 may first decode MIB and SB to obtain scheduling information of system information, and obtain at least one SIB using the obtained scheduling information.

Of course, before the mobile terminal 110 acquires the system information, by using a synchronization channel transmitted in a partial section of the PCCPCH, slot synchronization and frame synchronization of the corresponding cell are acquired. It is apparent to those skilled in the art that a primary scrambling code (PSC) corresponding to a corresponding cell should be obtained.

The 3GPP standard defines one MIB, two SBs (SB1 and SB2), and 18 SIBs (SIB # 1 to SIB # 18). The signaling handover parameter according to the present invention is transmitted through SIB # 11. desirable.

Here, SIB # 11 is an information block including measurement control information to be used in a corresponding cell, and the measurement control information includes a handover parameter.

The wireless network controller 130 may control at least one base station 120 according to the network design of the operator, and may change the system information to be broadcast to the corresponding cell by using a system information update message. have.

For example, when the signaling handover parameter of the cell needs to be changed, the radio network controller 130 may transmit a system information update message including a changed signaling handover parameter to a base station supporting the cell. 120).

The base station 120 may schedule the system information included in the received system information update message using the MIB and the SB, and then map the system information to the entire PCCPCH.

The core network 140 may not only perform general call processing and mobility management functions but also provide system information related to the core network to the wireless network controller 130.

The mobile communication network according to another embodiment of the present invention may further include an operation server 160 connected to the wireless network controller 130 to set handover parameters for each cell.

In particular, the operation server 160 according to the present invention collects call processing statistics information for each cell, automatically determines an optimized handover parameter based on the collected statistical information, and determines the determined handover parameter in the wireless network controller 130. ) Can be provided. Here, the call processing statistics may include call success rate per cell and traffic handover count information in a specific region.

For example, when the collected call success rate for each cell is low, the operation server 160 may update the signaling handover parameter and provide it to the radio network controller 130 to increase the call success rate. In addition, the operation server 160 may update the traffic handover parameter to reduce the system load and increase resource utilization efficiency by using the traffic handover frequency information generated in a specific region for a certain period of time.

According to another embodiment of the present invention, it should be noted that some or all of the functions performed on the operation server 160 may be implemented on the radio network controller 130.

2 is an RRC state transition diagram defined in the 3GPP standard.

As shown in FIG. 2, a radio resource control (RRC) state is largely divided into an idle mode 202 and a connected mode 206.

Here, RRC is a signaling protocol for transmitting and receiving control messages related to setup, reconfiguration, and release of a radio bearer between the UTRAN 150 and the mobile terminal 110. .

Each RRC state shown in FIG. 2 defines the types of transport channels that can be used by the mobile terminal 110 in idle mode 204 and connected mode 206 and how to operate in each state.

The idle mode 202 refers to a state in which the power of the mobile terminal 110 is off or there is no wireless connection between the mobile terminal 110 and the UTRAN 150.

That is, in idle mode 202, UTRAN 150 may not have any available information regarding the location of mobile terminal 110.

However, the location information of the mobile terminal 110 in the idle mode 202 may be referred to as a core network (hereinafter referred to as a CN (Core Network)) with an accuracy of a location area (LA) or a routing area (RA) according to the last location registered information. It can be maintained in the Home Location Register (HLR) or the Variable Location Register (VLR).

That is, in the idle mode 202, the UTRAN 150 may not know the terminal location information in units of cells or units of UTRAN Registration Area (URA).

Here, the URA refers to an area covered by a plurality of cells, and is position information which can be known only inside the UTRAN 150.

How do you combine the cells and define them as URA? Or will you use the concept of URA in your system? It will be apparent to those skilled in the art that such problems may vary depending on the service provider's decision.

However, when using URA according to the 3GPP standard, up to eight URAs can be allocated to one cell.

The mobile terminal 110 may obtain URA information corresponding to the cell through SIB # 2 (system information block type 2) information included in a broadcasting channel (BCH) transmitted by the UTRAN 150. That is, the SIB2 includes at least one piece of URA information associated with the cell.

If the mobile terminal 110 moves from the URA_PCH state 214 to a new URA not included in SIB2, it sends a URA update message to the UTRAN 150.

That is, the UTRAN 150 may manage the location in units of URA for the mobile terminal 110 in the URA_PCH state 114.

The connected mode 206 includes a Cell Dedicated Channel (DCH) state 208, a Cell Forward Access Channel (FACH) state 210, a Cell Paging Channel (PCH) state 212 and a URA PCH state 214.

The transition from idle mode 202 to connected mode 206 is through RRC connection setup 216 or 220.

Conversely, switching from connected mode 206 to dormant mode 202 is possible via RRC disconnection 218 or 222.

For example, when the mobile terminal 110 requests a new call establishment through the RACH (Random Access Channel)-ie, sends an RRC connection establishment request message to the UTRAN 150-the RRC state is in the dormant state 204. Transition to Cell FACH state 210.

If, in the Cell FACH state 210, the UTRAN 150 is a dedicated resource to the mobile station 110 through a Forward Access Channel (FACH), where the dedicated resource includes at least one of an SRB and an RB. Is assigned, that is, to transmit an RRC connection setup message to the mobile terminal 110, the RRC state of the mobile terminal 110 transitions to the Cell DCH state (208).

If the dedicated resource preset by the mobile terminal 110 or the UTRAN 150 is released, the RRC state transitions to the idle state 204.

In the following description, each state included in the connection mode 206 will be described in detail.

In general, the mobile terminal 110 may establish a wireless connection through a common channel or a dedicated channel.

In a wireless connection using a common channel (eg, FACH), low bit rate data needs to be transmitted between the mobile terminal 110 and the UTRAN 150, or data having burst characteristics is transmitted. It can be set to.

On the other hand, a dedicated channel may be set in a service requiring high data speed and low delay.

That is, the cell FACH state 110 may be used for transmitting data having low speed or burst characteristics or for transmitting the resource allocation information to the mobile terminal 110 by the UTRAN 150.

Here, when the radio channel is established using the resource allocation information, the RRC state of the mobile terminal 110 transitions to the Cell DCH state 208.

If there is no data to transmit in the Cell FACH state 210 or the Cell DCH state 208, the RRC state may transition to the Cell PCH state 212 or the URA PCH state 214.

Once the UE state transitions to Cell PCH state 212 or URA PCH state 214, the mobile terminal 110 according to the discontinuous reception cycles (DRX) information received from the UTRAN 150. Monitor the paging channel.

In this case, when the mobile terminal 110 receives a paging message through the paging channel, the mobile terminal 110 transmits a paging response message to the UTRAN 150 using a random access channel (RACH) and then transitions to the cell FACH state 210.

In particular, the URA PCH state 214 is periodically performed by the mobile terminal 110 when there is no data to be transmitted in the cell DCH state 208 or the cell FACH state 210 as well as when the mobile terminal 110 has high mobility. It can be used to avoid sending a Cell Update message to the UTRAN 150.

URA PCH state 214 may also be used to release dedicated resources allocated to mobile terminal 110.

In the Cell PCH state 212, the UTRAN 150 may acquire location information of the mobile terminal 110 at a Cell level, and may acquire the URA level in the URA PCH state 214.

3 is a flowchart illustrating an active set update procedure in a Cell_DCH state according to the present invention.

In more detail, FIG. 3 shows that when the UE 110 in the Cell_DCH state is located in the cell boundary region, the radio network controller 130 is activated through a preset SRB according to the measurement report message received from the UE 110. FIG. 7 illustrates a process of performing an active set update procedure.

Referring to FIG. 3, when the UE 110 moves from the first cell 302 to the cell boundary region (hatched area in FIG. 3) with the second cell 304, the CPICH of the second cell 304 When the strength of the signal 308 satisfies the preset reference value, a measurement report message including the strength information of the measured second cell CPICH signal 308 is transmitted to the radio network controller 130 through the SRB (S320). .

When the strength of the second cell CPICH signal 308 included in the measurement report message is greater than or equal to a preset criterion, the radio network controller 130 generates an active set update message for adding the second cell to the active set through the SRB. 110) (S330). Here, the active set update message includes dedicated channel assignment information corresponding to the second cell, and the UE 110 adds a new radio link to the existing active set using the received dedicated channel assignment information.

The UE 110 transmits an active set update complete message to the radio network controller 130 through the SRB indicating that the update of the active set is completed.

In general, the best cell of the mobile UE 110 may change frequently, and thus, the UE 110 may frequently transmit a measurement report message to the radio network controller 130 indicating that the best cell has changed. . Therefore, between the UTRAN 150 and the UE 110, an Add / Delete procedure of a radio link using an active set update procedure may frequently occur.

That is, the UE 110 performs handovers through measurement reports and active set update procedures, and frequent handovers can increase interference on the air interface and reduce overall radio capacity.

In particular, in the case of WCDMA, the UE 110 in the traffic state is allocated relatively more code resources than the UE 110 in the SRB state, and the frequent traffic handover requires the establishment of a plurality of radio links. Consumption multiplied by multiple. In addition, as the handover is performed, a problem may occur that the system load increases.

On the other hand, it is important for the UE 110 in the SRB state to control the handover parameter to move to the best cell as quickly as possible in order to minimize call disconnection probability.

For example, in the SRB state, important control procedures such as mode CM setting, security setting, and RB setting are performed through the preset SRB. Therefore, it is important to maintain an optimal radio link state so that the control procedure is normally performed.

On the other hand, in the traffic state, the RRC message and the Non Access Stratum (NAS) message transmitted and received through the SRB are less frequent, and their importance is lower than that of the control message transmitted and received in the SRB state. It is preferable that the state is set differently.

In general, a signal of a neighboring cell that is gradually getting stronger acts as an interference signal until it is included in an active set, where an active set means a set of cells performing handover with the UE 110. Therefore, the short handover delay time can minimize the interference of neighboring cells with respect to the reference link.

4 is a flowchart illustrating a method for changing a handover parameter according to a bearer state according to the present invention.

According to the 3GPP standard, the change of parameters related to handover may be provided differently according to the RRC state of the UE 110.

For example, the UE 110 in any one of the idle state 204, the Cell FACH state 210, the Cell PCH state 212, and the URA PCH state 214 may receive system information received through a broadcast channel. For example, handover parameters may be received via SIB 11-. On the other hand, the UE 110 in the Cell DCH 208 state may receive a handover parameter through any one of an RB Setup message and a measurement control message.

Measurement Control Procedures UTRA

N, Universal Terrestrial Radio Access Network (150) Setup, Modify and Release Measurement Targets to be Performed on a Mobile Terminal (hereinafter referred to as 'UE (User Equipment)', 110) Say a series of courses for.

For example, if there is a new measurement object to be performed by the UE 110, the UTRAN 150 measures a measurement command field, where the measurement command field is one field that constitutes a measurement control message. Can be set to at least one of Setup, Modify, and Release-Maps a Measurement Control Message (Setup) with a Dedicated Control Channel (DCCH) To the UE 110.

Here, the DCCH is a logical channel defined by 3rd Generation Partnership Project (3GPP) to transmit and receive control messages related to a specific UE.

The DCCH may be mapped and transmitted in any one of a forward access channel (FACH) or a dedicated channel (DCH) according to the RRC state of the UE.

In this case, the FACH and the DCH are mapped to physical channels called a secondary common control physical channel (SCCPCH) and a downlink physical data channel (DPDCH), respectively, and transmitted to the UE 110.

For example, when the RRC state of the UE 110 is the Cell FACH 210 state, the measurement control message is sequentially mapped to the FACH and the SCCPCH and transmitted to the corresponding UE 110.

On the other hand, when the RRC state of the UE 110 is the Cell DCH 208 state, the measurement control message is sequentially mapped to the DCH and the DPDCH and transmitted to the corresponding UE 110.

The UE 110 generates a measurement object for each measurement type and a measurement identifier included in the received measurement control message, and then starts measurement.

If the UE 110 determines that the measurement result satisfies the Measurement Reporting Criteria, the UE 110 transmits a measurement report message including the measurement result to the UTRAN 150.

Here, the measurement report criteria may be defined through an event type (eg, including Event 1f, Event 1g, etc.) and at least one threshold value corresponding to the corresponding event type.

The UTRAN 150 may control measurement reporting criteria by sending a measurement control message to the UE 110 that includes an event type and a threshold value corresponding to the measurement identifier.

The UE 110 continuously performs measurement until receiving a measurement control message for releasing a preset measurement object from the UTRAN 150.

In the following description, a method of changing the handover parameter according to the bearer setting state will be described in detail with reference to FIG. 4.

When the signaling handover parameter of a specific cell is changed, the UTRAN 150 maps the changed signaling handover parameter to the P-CCPCH of the corresponding cell and broadcasts it (S402).

The UE 110 decodes the P-CCPCH to obtain signaling handover parameters and stores them in a predetermined internal recording area (S404). Here, the signaling handover parameter is preferably transmitted through SIB 11.

After configuring the SRB through the RRC connection establishment procedure (S406), the UE 110 may perform SRB handover using the signaling handover parameter stored in step 404 through the configured SRB (S408).

The UE 110 may set an RB for transmitting and receiving traffic through the RB Setup message received from the UTRAN 150, and acquire a traffic handover parameter (S410). In this case, the obtained traffic handover parameter may be stored in a predetermined recording area (S412).

Thereafter, the UE 110 may measure the neighbor cell using the traffic handover parameter and perform a handover procedure accordingly (S414).

5 is a diagram for explaining a handover algorithm in WCDMA.

Referring to FIG. 5, the WCDMA handover algorithm includes a Radio Link Addition (Event 1A, 570), a Radio Link Removal (Event 1B, 580), and a Combined Radio Link Addition and Removal (Event 1C, 590).

Each WCDMA handover algorithm may be controlled through parameters such as reporting range, hysteresis, and timeToTrigger.

Here, the reporting range is a threshold value that can be set for each soft handover algorithm, and a value between 0 and 29 dB may be set in 0.5 dB units. In the following description, the reporting ranges for Radio Link Addition (Event 1A, 570) and Radio Link Removal (Event 1B, 580) will be referred to as RR_Event_1A and RR_Event_1B, respectively. However, note that the reporting range for Combined Radio Link Addition and Removal (Event 1C, 590) is not defined.

Hysteresis uses Hysteresis_event_1A to add new radio links to the active set, Hysteresis_event_1B to remove specific radio links from the active set, and Hysteresis_event_1C to replace the weakest cell in the active set with the strongest candidate cell. It may include.

ΔT is HO_Add_time 540, which is an evaluation window size for evaluating addition of a candidate cell to an active set, HO-Drop_time 560, which is a window size for evaluating whether a specific cell is removed from an active set, and active HO_Replace_time 550, which is a window size for evaluating whether the weakest cell of the set is replaced with the strongest cell of the candidate set, may be included.

In the following description, the WCDMA soft handover algorithm will be described in detail with reference to FIG. 5.

If, during HO_Add_time (540) Equation 1:

Pilot_ Ec / Io > Best_Pilot_ Ec / Io -RR_Event_1A + Hysteresis_event_1A

UTRAN 150 does not exceed the number of cells that can be included in the preset maximum active set, hereinafter referred to as the "maximum active set number", the UTRAN 150 adds the cell to the active set.

Referring to FIG. 5, when the Ec / Io 520 of CPICH measured corresponding to Cell 2 during HO_Add_time 540 exceeds the value of the right side of Equation 1 above and does not exceed the maximum number of active sets, Cell 2 Is added to the active set.

If, during HO_Drop_time (560) Equation 2:

Pilot_ Ec / Io > Best_Pilot_ Ec / Io -RR_Event_1B-Hysteresis_event_1B

If is satisfied, the cell is removed from the active set.

Referring to FIG. 5, when Ec / Io 530 of CPICH measured corresponding to Cell 3 during HO_Drop_time 560 exceeds the value of the right side of Equation 2, Cell 3 is removed from the active set.

If the maximum number of active sets is completely full, during HO_Replace_time (550), Equation 3:

Best_candidate_Pilot_ Ec / Io > Worst_Old_Pilot_ Ec / Io -Hysteresis_event_1C

If is satisfied, the weakest cell in the active set is replaced with the strongest candidate cell.

Referring to FIG. 5, the current active set includes Cell 1 and Cell 2, and the candidate cell set includes Cell 3. If the maximum number of active sets is completely full, assuming that the maximum number of active sets in this embodiment is 2, CPICH Ec / Io 530 of Cell 3 is CPICH Ec of Cell 1 during HO_Replace_time 550. If / Io (510) exceeds the value obtained by subtracting Hysteresis_event_1C, Cell 1 is removed from the active set and Cell 3 is added to the active set. Here, Best_candidate_Pilot_Ec / Io means a cell in which the strongest signal of the candidate cell set is measured, and Worst_Old_Pilot_Ec / Io means a cell in which the weakest signal of the cells included in the active set is measured.

As described above, addition / deletion / replacement of cells during soft handover may be controlled through handover parameters such as reporting range, hysteresis, and timeTrigger (ΔT).

The method for controlling a handover parameter according to an exemplary embodiment of the present invention controls the handover parameter so that handover can be performed more quickly with respect to the SRB state, and handover is relatively slow in comparison with the SRB state in the traffic state. It is desirable to control to be performed.

6 is a block diagram of an operation server according to an embodiment of the present invention.

As shown in FIG. 6, the operation server 160 includes a message transmitter / receiver 610, a controller 620, a handover parameter generator 630, an event handler 640, an event generator 650, and SRB statistics. Database 660, RB statistics database 670.

The message transmitter / receiver 610 provides a message interface with the wireless network controller 130.

The controller 620 analyzes the message received from the message transmitter / receiver 610 and updates the corresponding database, where the database includes the SRB statistics database 660 and the RB statistics database 670, and generates handover parameters. When the handover parameter is received from the unit 630, a predetermined handover parameter update message is generated and transmitted to the message transmitter / receiver 610.

For example, the controller 620 receives a call processing related message from the radio network controller 130, and uses the received call processing related message to call processing statistics information about SRBs and RBs for each cell, where call processing statistics The information may be collected per cell, and the generated statistical information may be stored in a corresponding database.

Here, the call processing related message may include a handover related message as well as a message related to the setup / reconfiguration / release / fault of a call. In addition, the controller 620 may obtain frame error rate (FER) information for each caller from the radio network controller 130 and store the obtained FER information in a corresponding database.

The handover parameter generator 630 generates a new handover parameter that satisfies the call success rate and the quality of service according to the control signal of the event handler 640, or by the user through the operation terminal 680. A function of receiving the input handover parameter and transmitting the received handover parameter to the controller 620 may be performed.

For example, when the handover parameter generation unit 630 receives a predetermined control signal instructing to update the signaling handover parameter and a predetermined control signal instructing the update of the traffic handover parameter from the event handler 640. In addition, a handover parameter corresponding to the control signal may be determined and transmitted to the controller 620.

The event handler 640 generates a handover parameter update request signal corresponding to the control signals received from the event generator 650 and the operation terminal 680 and transmits the corresponding handover parameter update request signal to the handover parameter generator 630.

For example, when a user inputs a handover parameter to change through a predetermined user interface on the operation terminal 680 and presses an OK button, the event handler 640 reads the input parameter and includes the read parameter. The handover parameter update request signal may be transmitted to the handover parameter generator 630.

In addition, when the event handler 640 receives an event related to handover parameter update from the event generator 650, the event handler 640 generates a handover parameter update signal corresponding to the received event to the handover parameter generator 630. Can transmit Here, the event generated by the event generator 650 may include a signaling parameter update event indicating that the signaling handover parameter needs to be changed and a traffic parameter update event indicating that the traffic handover parameter needs to be changed. .

The event generator 650 may perform a function of generating a specific event by using call processing statistics information stored in the SRB statistics database 660 and the RB statistics database 670.

For example, the event generator 650 may generate a signaling parameter update event when the signaling handover success rate stored in the SRB statistics database 660 does not satisfy a predefined reference value.

In addition, the event generator 650 may generate a traffic parameter update event when the traffic handover success rate stored in the RB statistics database 670 does not satisfy a predefined reference value.

The event generator 650 according to an exemplary embodiment of the present invention preferably analyzes the handover success rate for signaling and traffic in units of cells and generates an event in units of cells according to the analysis result.

The SRB statistics database 660 and the RB statistics database 660 maintain cell-specific call processing statistics for signaling and traffic, respectively, and may be updated by the controller 620. Here, the call processing statistical information may include a handover success rate, a handover delay time, a frame error rate (FER), etc. for each of the signaling state and the traffic state.

In the above description, only the event generation unit 650 generates an event according to the handover success rate. However, according to another embodiment of the present invention, the event generation unit 650 may include the above handover success rate, It should be noted that at least one of a handover delay time and a frame error rate (FER) may be used to determine whether an event occurs.

Here, the handover delay time means a delay time from when the handover is determined by the radio network controller 130 to when the handover is completed, and FER indicates an error rate for a frame generated during the handover delay time. it means.

When the wireless network controller 130 according to the present invention receives the handover parameter update message received from the operation server 160, it may update the handover parameter for signaling or traffic handover of the mobile terminal connected to the corresponding cell. Can be.

For example, the change of the signaling handover parameter may be performed using a system information update message defined in 3GPP standard 25.433, and the change of the traffic handover parameter may be performed by a radio bearer setup message defined in the 3GPP standard. ) And a Measurement Control Message.

Here, it is noted that a radio bearer setup message and a measurement control message are transmitted from the radio network controller 130 to the mobile terminal 110 through the RRC protocol through an SRB set in the corresponding mobile terminal. Should be.

In particular, the wireless network controller 130 transmits the traffic handover parameter through the radio bearer setup message when the RB for the specific mobile terminal is not set, and transmits the traffic handover parameter through the measurement control message after the RB is established. You can change it.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

1 is a block diagram of a mobile communication network according to an embodiment of the present invention.

2 is an RRC state transition diagram as defined in the 3GPP standard.

3 is a flowchart illustrating an active set update procedure in a Cell_DCH state according to the present invention.

4 is a flowchart illustrating a method for changing a handover parameter according to a bearer state according to the present invention.

5 is a diagram for explaining a handover algorithm in WCDMA.

6 is a block diagram of an operation server according to an embodiment of the present invention.

* Key Drawing

110: UE (User Equipment)

120: base station (NodeB)

130: Radio Network Controller (RNC)

150: Universal Terrestrial Radio Access Network (UTRAN)

160: production server

620: control unit

630: handover parameter generator

640: event handler

650: event generator

660: SRB Statistics Database

670: RB Statistics Database

Claims (10)

A method for controlling handover parameters in a wireless network controller of a wideband code division multiple access (WCDMA) system, Transmitting a signaling handover parameter corresponding to a specific cell to a base station using a system information update message; And Receiving a call setup request signal from the mobile terminal, the SRB is set, and the traffic handover parameter is transmitted to the mobile terminal using a radio bearer setup message through the set signaling radio bearer (SRB). The method of claim 1, wherein the base station transmits the signaling handover parameter using a broadcast channel of a corresponding cell. The method of claim 1, If it is necessary to change the traffic handover parameter, a handover parameter in the wireless network controller, characterized in that for transmitting a measurement control message (Measurement Control Message) including the traffic handover parameter to be changed to the mobile terminal via the SRB. Control method. The method of claim 1, The signaling handover parameter and the traffic handover parameter are reporting range, hysteresis, and trigger time that are reference values for determining whether to add, delete, or replace a specific cell on an active set. Handover parameter control method in a wireless network controller comprising a (timeToTrigger). The method of claim 1, The signaling handover parameter is mapped to an eleventh system information block (SIB # 11) of the broadcast channel and transmitted. The method of claim 1, By the mobile terminal, Acquiring the signaling handover parameter from the broadcast channel and performing signaling handover using the acquired signaling handover parameter; And When receiving the radio bearer setup message through the SRB, the step of setting the radio bearer and performing traffic handover using the traffic handover parameter is performed. Control method. A method for controlling handover parameters in a device connected to a wireless network controller of a wideband code division multiple access (WCDMA) system, Generating call processing statistics information by using call processing related messages received from the radio network controller; An event generation step of determining whether to update a handover parameter for each cell by using the generated call processing statistics information and generating a predetermined event according to the determination result; A handover parameter updating step of updating an optimized handover parameter according to the generated event; And An update parameter transmission step of transmitting a predetermined handover parameter update message including the updated handover parameter to the radio network controller; Handover parameter control method comprising a. The method of claim 6, And the call processing statistical information includes at least one of a handover success rate in a signaling state and a traffic state, a handover delay time, and an error rate for a frame generated during handover. According to claim 7, The event generation step Comparing whether the handover success rate corresponding to each of the signaling state and the traffic state satisfies a predefined threshold value for each state; Generating a signaling parameter update event when the handover success rate in the signaling state does not satisfy a corresponding threshold as a result of the comparison; And  Generating a traffic parameter update event when the handover success rate in the traffic state does not satisfy a corresponding threshold as a result of the comparison Handover parameter control method comprising a. An apparatus for controlling a handover parameter by connecting to a wireless network controller of a wideband code division multiple access (WCDMA) system, A control unit for analyzing call processing related messages received from the radio network controller, generating call processing statistics information, and generating and transmitting a control message including an updated handover parameter to the radio network controller; An event generator configured to determine whether to update a handover parameter by using the generated call processing statistics information and to generate an event according to the determination result; And A handover parameter generator for generating an optimized handover parameter according to the generated event and transmitting the generated handover parameter to the controller. Handover parameter control device comprising a. The method of claim 9, The call processing statistics information includes a signaling handover success rate and a traffic handover success rate for each cell.

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