KR20070079944A - Method and apparatus for mesurement of handover of active mode user equipment in a mobile communication system - Google Patents

Abstract

A method and an apparatus for managing neighbor cells of an active mode terminal in a mobile communication system are provided to define an event supporting the handover of an active mode terminal in accordance with a 3GPP(3RD Generation Partnership Project) LTE(Long Term Evolution) system and to minimize power consumption of the active mode terminal in executing management for neighbor cells in the 3GPP LTE system. A UE(User Equipment) transmits a measurement report message to inform an E-RAN(Evolved Radio Access Network) that a handover event has been generated(221). In this case, the measurement report message contains a cell identifier of a neighbor cell "A", which has generated the handover event, and a management result value related to the cell "A". Then, the UE activates a measurement stopping timer to stop management for the cell "A". If a handover command is not received from the E-RAN until the timer expires, the UE doesn't execute management for the cell "A" anymore by recognizing that handover cannot be executed due to a network situation. In case it is impossible to perform handover to the cell "A", the E-RAN, receiving the measurement report message, doesn't carry out handover procedures for the UE(231), and updates a context associated with the radio state of the UE in order to put the cell "A" in a list of cells having better radio strength than the present serving cell "X"(233). Also, the E-RAN doesn't transmit a handover command message to the UE(241). The UE also puts the cell "A" in a list of cells having better radio strength than the serving cell "X"(251), and then stops management for the cell "A"(253).

Description

METHOD AND APPARATUS FOR MESUREMENT OF HANDOVER OF ACTIVE MODE USER EQUIPMENT IN A MOBILE COMMUNICATION SYSTEM}

1 is a diagram showing the structure of a 3GPP next generation mobile communication system to which the present invention is applied;

2 is a diagram illustrating a measurement procedure of an active mode terminal according to an embodiment of the present invention.

3 is a signal flow diagram illustrating a measurement operation of a terminal according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a structure of a terminal according to an exemplary embodiment of the present invention.

5 is a signal flow diagram illustrating a management process procedure of a network node according to an embodiment of the present invention.

6 is a signal flow diagram illustrating another measurement processing procedure of a network node according to an embodiment of the present invention.

7 is a diagram illustrating a structure of a network node according to an embodiment of the present invention.

The present invention relates to a mobile communication system, and more particularly, to a method and apparatus for measurement of an adjacent cell of an active mode terminal.

The Universal Mobile Telecommunication Service (UMTS) system is based on the European system of Global System for Mobile Communications (GSM) and General Packet Radio Services (GPRS), and is used for wideband code division multiple access (hereinafter referred to as " CDMA ') is a third generation asynchronous mobile communication system (3GPP).

The 3GPP system defines a handover procedure and a measurement report procedure to support mobility of CELL_DCH (CELL_Dedicated channel) terminal.

First, the CELL_DCH terminal indicates a terminal in a Radio Resource Control (RRC) state, which is a connected mode in which the terminal state can transmit and receive signaling with a network. Dedicated data / control channel: Dedicated Physical Data Channel (DPDCH), Dedicated Physical Control Channel (DPDCH).

On the other hand, when the cell (serving cell) in which the terminal is located is changed due to the mobility of the terminal, the handover may continuously receive the dedicated data / control channel received by the terminal even in the changed cell (target cell). Represents a series of procedures to ensure

In addition, the measurement report indicates a series of procedures in which the terminal measures a radio condition of a current cell and a plurality of neighbor cells adjacent to the current cell and reports it to the network to support the handover.

In summary, the terminal informs the network of the measurement result of the radio state of the current cell and neighbor cells through a measurement report message, and if necessary, the network targets the terminal based on the measurement report message. cell, or handover.

At this time, if the network node controlling the target cell is different from the network node controlling the previous cell (serving cell), information exchange for the terminal between the network nodes, service information exchange of the terminal, and data / Resource reservation for control transmission may be performed.

The measurement report for handover includes an intra-frequency handover, an inter-frequency handover, an inter-system handover (Inter-RAT (Radio Access Technology) handover)), and Likewise, it can be classified into measures for three purposes.

The intra-frequency handover is a handover to a neighbor cell of the same frequency band as the current cell of the terminal, the inter-frequency handover is a handover to a neighbor cell of a frequency band different from the current cell, and the inter-system handover is the current Represents a handover to a cell and a neighbor cell belonging to another system.

In addition, the measurement report is defined as two types of periodic measurement report (Periodic measurement report) and event triggered measurement report (Event triggered measurement report) according to the event occurrence.

The periodic measurement report informs the network node of a measurement result of a radio state of a current cell and neighboring cells measured by a terminal periodically at regular intervals. On the other hand, the event generation measurement report is to inform the network node of the measurement result when the event occurs after predefining a specific event.

Table 1 below shows an event list defined in the 3GPP system for intra-frequency measurement reporting.

Referring to <Table 1>, events 1a to 1f are events for reporting a frequency within a frequency division duplex (FDD) system, and events 1g to 1i are time division duplex (TDD: Time). Division Duplex) Events for in-band measurement reporting that can be used in a system. In particular, Event 1a, 1b, 1c are generally events defined for soft handover.

Here, soft handover means that when the terminal is in the handover region, while adding a new radio link from the target cell and continuously maintaining the previous radio link from the source cell. That is, it shows a smooth handover from the source cell to the target cell while obtaining the combining gain while receiving the same data / control information from the two radio links from the target cell and the source cell. If the terminal moves out of the handover area and moves closer to the center of the target cell, then the radio link from the source cell is disconnected.

When Event 1a occurs, the terminal informs the network node of the first common pilot channel (hereinafter referred to as P-CPICH) that generated the event. Generally, if there is no restriction on other factors, for example, If there is no limit such as the number of cells that can establish a radio link for the terminal at the same time, or the overload state of the target cell, the network may add a new radio link for the terminal from the cell indicated by the P-CPICH. Add

On the other hand, when Event 1b occurs, the terminal informs the network node of the P-CPICH that generated the event, and in general, if there is no restriction on other factors, the network provides for the terminal from the cell indicated by the P-CPICH. Remove the radio link.

Event 1c is an in-frequency measurement report event for maintaining an active set. The active set is a set of radio links owned by the terminal. For example, if the terminal is in a handover area and maintains a radio link from cell A and cell B, the active set for the terminal is cell A and cell B. Indicates.

When the Event 1c occurs, this indicates that a cell having a better radio state is generated than cells included in the active set currently maintained, and the terminal informs the network node of the P-CPICH that generated the event. If there is no restriction on other factors, the network replaces the cell indicated by the P-CPICH with the cell of the weakest radio state of the active set. At this time, the radio link for the terminal is added from the cell indicated by the P-CPICH, while the radio link from the cell of the weakest radio state included in the active set is deleted.

Event 1d is an event for a High Speed Data Packet Access (hereinafter referred to as HSDPA) service. HSDPA represents a radio access method for supporting a high speed down-link (DL) packet service through a shared channel using a hybrid automatic repetition request (HARQ) and scheduling.

Since the HSDPA does not support soft handover unlike a general dedicated channel, the HSDPA generally performs handover along a cell having the best radio state. If a new radiolink to the destination cell is added when the terminal is in the handover area, the radio link from the source cell is broken. That is, it cannot have multiple radio links from different cells at the same time.

Such a handover is called a hard handover.

Therefore, when the Event 1d occurs, the terminal informs the network node of the P-CPICH that generated the event, and in general, if there is no restriction on other factors, the network provides HSDPA serving of the cell indicated by the P-CPICH. Cell), disconnect the link for the HSDPA service from the serving cell and establish a link for the HSDPA service from the target cell.

Event 1e and 1f may be used when the network wants to manage cells in a radio state that are better than a threshold specified by a specific absolute value of the terminal. Event 1e may cause the terminal to report to the network node cells of a radio state better than a certain absolute threshold. On the other hand, by the Event 1f, the terminal may report to the network node that the radio state was better than the specific absolute threshold by the Event 1e, but again worse than the specific absolute threshold. The specific absolute thresholds for the Event 1e and 1f may be the same or may have different values.

Depending on the operator's policy, Event 1e, 1f may be used for soft handover instead of Event 1a, 1b.

As described above, in the conventional mobile communication system, a plurality of measurement report events for measurement reporting are defined.

According to such a measurement procedure, the complexity of the terminal and the increase in the measurement report transmission according to a plurality of measurement report events may increase signaling overhead.

Therefore, in the newly proposed mobile communication system, it is necessary to define an in-measurement report event that is distinguished from the conventional mobile communication system, and define a more efficient message reporting method and handover procedure.

Accordingly, the present invention devised to solve the problems of the prior art operating as described above, provides a method and apparatus for the management of the adjacent cell of the active mode terminal in the mobile communication system.

The present invention also provides a method and apparatus for handover after performing a measurement on an adjacent cell of an active mode terminal in a mobile communication system.

In addition, the present invention provides a method and apparatus for handover after an active mode terminal performs a measurement report on a target cell while minimizing power consumption in a mobile communication system.

The present invention also provides a method and apparatus for performing a handover by performing a measurement again when an active mode terminal fails to handover due to a load state of a target cell in a mobile communication system.

According to an aspect of the present invention, there is provided a method of adjacent cell management of an active mode terminal in a mobile communication system, the method comprising: detecting a measurement report event by a terminal and wirelessly transmitting a measurement report message including target cell information corresponding to the event; Transmitting a handover command message corresponding to the measurement report message from the E-RAN before the timer expires; transmitting to an access network (E-RAN), operating a timer in response to the measurement report message. If it is not received, stopping the measurement for the target cell when the timer expires, and receiving the re-measurement indication message from the E-RAN, and then releasing the suspension for the target cell. It is characterized by including.

The present invention provides a method for handovering an active mode terminal by an E-RAN in a mobile communication system, the method comprising: receiving a measurement report message including target cell information corresponding to a measurement report event from the terminal; And determining the handover by checking the load state of the target cell, and determining that handover cannot be performed to the target cell, rather than serving cells of each terminal of a context configured for each terminal. Transmitting a re-measurement indication message to the terminal if it is determined that the target cell is included in the cell list including the specific cells having a good radio strength and that handover is possible to the target cell; After receiving the measurement report message including the measurement result value for the target cell from the terminal, And transmitting a drawover command message.

According to an aspect of the present invention, in a handover method in a mobile communication system, the terminal having a radio access control (RRC) connection with a serving cell detects that the radio strength of a specific neighboring cell adjacent to the serving cell is greater than the serving cell, Reporting a measurement to a radio access network (E-RAN), waiting to receive a handover command for a timer time set in response to the reporting from the E-RAN, and when the timer expires, the neighbor Terminating the measurement for the cell; and transmitting the re-measurement indication message for the neighboring cell to the terminal so that the terminal performs the measurement for the neighboring cell again. And receiving a measurement report from the terminal again and handing command to the neighbor cell.

According to an aspect of the present invention, there is provided a terminal device for handover in a mobile communication system, comprising: a management unit for managing a cell including a serving cell to which radio connection control (RRC) is connected, and adjacent cells having a radio strength greater than that of the serving cell; A measurement performing unit for detecting a measurement report event by measuring the radio strength of the serving cell and the radio strength of the neighbor cells, and performing a measurement on the specific neighbor cell for a predetermined timer; Correspondingly transmitting a measurement report message to a radio access network (E-RAN) and receiving a handover command message for receiving a handover command message for a predetermined time in response to the measurement report message; It characterized in that it comprises a timer controller for providing time information for.

The present invention provides a network device for handover instruction in a mobile communication system, the method comprising: receiving a measurement report message including target cell information from a specific terminal in response to a measurement report event, and in response to the measurement report message; A transceiver for transmitting a handover command message to a target cell and a cell list including information on a serving cell and neighboring cells having a radio strength greater than that of the serving cell in correspondence with the measurement report message; A cell manager for updating the cell list according to the handover decision to the target cell, a radio resource manager for determining whether to handover the terminal to a specific neighbor cell in response to the measurement report message, and handing the terminal to the target cell It characterized in that it comprises a handover performing unit to over.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily flow the gist of the present invention, the detailed description thereof will be omitted.

Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

Hereinafter, the present invention will be described as an example of a long term evolution (LTE) system, which is a new generation mobile communication system under discussion, in a 3rd generation partnership project (3GPP) system currently in charge of UMTS standardization.

The present invention proposes a measurement reporting and handover procedure in an LTE system.

First of all, the LTE system is a technology for implementing high-speed packet-based communication of about 100 Mbps, and various methods of how to operate the system have been discussed in detail.

For example, the LTE system is under discussion to reduce the number of nodes located on the communication path by simplifying the structure of the network, and to bring wireless protocols as close to the wireless channel as possible.

As a result, the structure of the LTE system is expected to change from the 4-node structure in the existing 3GPP system to a two-node or three-node structure.

1 illustrates an example of a structure of a next generation (Evolved) mobile communication system to which the present invention is applied.

Referring to FIG. 1, a UE of 110 represents a terminal for an LTE system, and an Evolved Radio Access Network (E-RAN) of 140 refers to a base station (Node B) and an RNC (RNC) in an existing 3GPP system. A network device including a role of a radio network controller.

For reference, in a 3GPP system, a Node B manages cells as a wireless base station apparatus directly involved in communication with a terminal, and the RNC controls a plurality of Node Bs and controls radio resources.

In this regard, the E-RAN 140 physically combines the roles of an Evolved Node B (E-NB) 120 and an Evolved RNC 130 (E-RNC) into one node ( Merge may be processed, or may be configured separately from other nodes that are distinct from each other.

The E-CN 150 may be a node that combines the functions of a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN) of an existing 3GPP system. The E-CN 150 is located between a packet data network (PDN) 160 and the E-RAN 140 to allocate an IP (Internet protocol) address to the terminal 110 and the terminal 110. Serves as a gateway for connecting the packet data network. In the present invention, the system of FIG. 1 will be referred to as an embodiment, but the gist of the present invention includes that the same can be applied to the existing 3GPP system or other systems.

Hereinafter, the present invention will be described as an example of intra-frequency measurement reporting for intra-frequency handover for ease of explanation, inter-frequency measurement / handover or Obviously, it can be applied to inter-RAT (Radio Access Technology) measurement / Handover.

2 is a diagram illustrating a measurement procedure and a measurement reporting procedure according to the present invention.

<First Embodiment>

First, in the present invention, one intra-frequency measurement report event is defined as shown in Table 2 below with respect to intra-frequency handover.

The in-band measurement report event of Table 2 below indicates that a cell having a radio strength higher than that of a serving cell (a cell in which a terminal is currently located and serving signaling / data for the terminal) is found. .

Referring to FIG. 2, 201 is a terminal in an active mode. That is, the terminal 201 is in an active mode capable of transmitting and receiving signaling with the E-RAN 202 in an RRC connection state. In addition, the terminal 201 may transmit / receive data with the E-RAN 202 using radio resources allocated within a time allocated by scheduling information.

The E-RAN 202 may transmit / receive data for the service with information about the terminal 201 and context information about a service for the terminal 201.

The terminal 201 continuously performs measurement on adjacent cells in frequency. In this case, the terminal 201 detects that an intra-frequency measurement report event occurs in step 211.

According to the present invention, it is assumed that the serving cell of the terminal 201 is cell X and the neighbor cell is cell A. Hereinafter, the present invention will be described with an example in which a neighboring cell A has a better radio strength than the serving cell X as a result of intra-frequency measurement.

In step 221, the terminal 201 notifies the E-RAN 202 that an event for performing handover within the frequency occurs by transmitting a measurement report message in step 221. The measurement report message of step 221 may include a cell identifier for the neighbor cell A that generated the event, and a measurement result value for the cell A. Alternatively, the method may further include a measurement result (measurement) value of the current serving cell.

If the transmission of the measurement report message is started in step 221 or the transmission of the measurement report message is successfully completed, the terminal 201 does not receive a handover command to the cell A until a timer expires. A timer (Measurement Stopping Timer) for stopping the operation of the cell A is operated.

That is, the timer is a reception waiting timer for receiving a handover command (HANDOVER COMMAND) including performing a handover from the E-RAN 202 to the cell A. Measurement is continuously performed for the cell A.

At this time, if the terminal 201 does not receive a handover command from the E-RAN 202 to the cell A until the timer expires, the terminal 201 indicates that the handover to the cell A is in a network condition, eg For example, it is recognized that the cell A is impossible due to the loaded state (Cell A is loaded) and the like and no longer performs the operation on the cell A.

Meanwhile, in step 231, the E-RAN 202 receiving the measurement report of step 221 is included in the measurement report message, for example, because the situation of cell A is loaded. It is determined that handover cannot be performed to cell A. Therefore, the E-RAN 202 does not perform a handover procedure corresponding to the terminal 201.

In step 233, the context associated with the radio state of the terminal 201 is updated. That is, the E-RAN 202 does not change the serving cell for the terminal 201 but includes the cell A in the cell list of radio strength better than the current serving cell X.

This is to allow the terminal to resume the measurement for the cell A when the load situation of the cell A is changed later and the terminal 201 can be handed over to the cell A. The result of the resumed measurement procedure is to handover to the cell A if the radio strength of the cell A is better than the current serving cell X.

According to the steps 231 and 233, the E-RAN 201 does not transmit a HANDOVER COMMAND message to the terminal 201 in step 241.

Here, the handover command is a message for reconfiguring radio resources and the like to the terminal 201 as the E-RAN 201 determines the handover with respect to the terminal 201. That is, the handover command message may include information about a radio resource to be used in the corresponding cell.

Accordingly, since the handover command to the cell A has not been received until the timer at which the operation started at the transmission or transmission end point in step 221 ends, in step 251, the terminal 201 is better than the serving cell X. The cell A is included in the cell list having intensity. In response to the failure of receiving the handover command to the cell A, the terminal 201 stops the measurement for the cell A in step 253. This is for efficient power saving of the terminal and recognizes that handover to the cell A is impossible and stops the measurement procedure for the cell A.

In step 261, the E-RAN 202 determines that handover is possible with respect to the cell A. FIG. For example, the state that is the load load of the cell A may be caused by changing to a state other than the load load.

In step 263, the E-RAN 202 instructs the terminal 201 to perform a handover for the cell A, that is, perform a re-measurement for the cell A. In this case, the RE-MEASUREMENT INDICATOR may include information such as a cell ID indicating the cell A.

In addition, the re-measurement instruction message of step 263 may be transmitted only to the terminal 201. Or, the cell A may be transmitted to a plurality of terminals that were better than the serving cell but were unable to handover. Alternatively, the cell A may be transmitted to each of all terminals that were better than the serving cell but were unable to handover.

In this case, the E-RAN 202 manages a serving cell for each terminal and a cell list having better radio states than the serving cell (hereinafter, referred to as 'better cells'). One specific terminal or a plurality of terminals to receive the measurement indication message may be selected.

For example, in step 233 of FIG. 2, the E-RAN 202 includes the cell A having a better radio state than the serving cell x of the terminal 201 in better cells for the terminal 201. Doing. Accordingly, a redirection instruction indicating the re-measurement of the cell A is transmitted to the terminal 201 through the cell list.

Meanwhile, in order to reduce signaling overhead caused by the transmission of the re-measurement indication message in step 263, even though the cell A is included in the better cells, a channel quality indicator (CQI) currently being received is provided. If the Quality Indicator is sufficiently high, the re-measurement report of step 263 may not be transmitted.

That is, when transmitting the re-measurement indication message to one or more terminals, other elements, such as better cell context information of the corresponding terminal, as well as radio status of the current serving cell of the terminals, may be referred to. At this time, one or a plurality of terminals to receive the re-measurement instruction message should be informed using the ID of the terminal.

If the cell A is better than the serving cell X, but is transmitted to all terminals that cannot be handed over, in step 263, the cell A is transmitted as a common message that can be received by all terminals, not a message transmitted to a specific terminal.

In step 271, the terminal receiving the re-measurement indication message checks its own better cells to perform re-measurement. In step 281, the terminal 201 re-measures the cell A. As a result, it is detected that a measurement reporting event occurs. That is, as a result of re-measuring the cell A, it is confirmed that the cell A has a better radio strength than the serving cell x.

In step 291, the terminal 201 transmits a measurement report for the cell A to the E-RAN 202. The measurement report message of step 291 may include ID information indicating the cell A, a measurement result value for the cell A, that is, a measurement value. In addition, it may further include a measurement result value of the current serving cell.

Upon receiving the measurement report message, the E-RAN 202 determines to handover to the cell A in step 293, and transmits a handover command to the terminal 201.

<< second embodiment >>

The following second embodiment proposes a procedure that is partially different from that of the first embodiment described above.

According to the second embodiment below, the E-RAN 202 receives the management report message in step 221, but fails to handover the terminal 201 to cell A as shown in step 231. A message (hereinafter referred to as 'MEASUREMENT STOP INDICATOR') is transmitted to the terminal.

That is, a direct message indicates that the cell A has a better radio strength than the serving cell x but fails to hand over to the cell A. The terminal 201 receives the measurement stop indication message and causes the measurement for the cell A to stop.

The measurement stop indication message includes indicator information for stopping the measurement for the cell A, an identifier of a neighboring cell to stop the measurement, and a timer corresponding to how long to stop the measurement for the neighboring cell. May contain information.

In this case, when timer information is not included in the measurement stop indication message, the terminal 201 resumes the measurement for the neighbor cell when receiving the re-measurement indication message. On the other hand, when the timer information is included, the terminal 201 automatically performs the measurement for the neighbor cell without receiving the re-measurement message from the E-RAN 202 when the set timer ends. Resume.

In other words, according to the second embodiment of the present invention, if the terminal 201 resumes the measurement and a measurement report event as in step 211 occurs again, the measurement report of step 221 is performed for the generated cell. Transmit to the E-RAN 202.

When receiving the measurement stop indication message including the cell identifier to stop the measurement and timer information indicating the measurement stop period, the E-RAN 202 receives the message until the timer expires again. Stop the measurement for Thereafter, when the timer expires, the operation of resuming the measurement for the cell is repeated.

<< Third Embodiment >>

In the following third embodiment, an example of applying another measurement report event when the terminal 201 receives the re-measurement indication message from the E-RAN 202 will be described.

According to an embodiment of the present invention, when a measurement report event, that is, a cell having a radio strength better than the current serving cell where a terminal is located, is detected, the terminal that has received a re-measurement indication message of step 263 ( Only when 201) performs the re-measurement for the cell A, and the re-measurement result for the cell A is better than the current serving cell, the measurement report of step 291 is transmitted to the E-RAN 202. It explains what to do.

On the other hand, in the third embodiment, when the terminal 201 receives the re-measurement instruction from the E-RAN 202, the cell A, unlike the first embodiment, has a radio strength that is worse than that of the current serving cell. When it has, it sends the measurement report of step 291 to the E-RAN (202).

This can be set as a measurement report event as shown in Table 3 below.

Alternatively, in the third embodiment, when the terminal 201 receives the re-measurement indication message of step 263 from the E-RAN 202, the measurement result for the cell A is better than the serving cell. It may be set to send the measurement report of step 291 for the cell A to the E-RAN, regardless of whether or not having a bad radio strength.

This can be set as a measurement report event as shown in Table 4 below.

3 is a signal flow diagram of a terminal according to the present invention.

3 illustrates an example of a method of using a timer in the terminal of FIG. 2 and a time of using a measurement report event (A cell is better than serving cell). In addition, the method includes the method of using the measurement stop indication message further described in FIG. 2 and the method of using the measurement report event in two different cases described.

Referring to FIG. 3, in step 301, the terminal is switched to the active mode.

In step 311, the terminal performs a measurement. In operation 311, the intra-frequency measurement is taken as an example according to an embodiment of the present invention. However, the present invention includes inter-frequency measurements and inter-system measurements. In other words, it is important to perform a measurement on a serving cell of a current terminal and an adjacent cell adjacent to the serving cell.

According to an example of the present invention, in step 311, the measurement is performed on radio strength of neighboring cells of the same frequency as the serving cell of the terminal.

In addition, the present invention includes the radio frequency measurement for measuring the radio strength of the serving cell of the terminal and neighboring cells of different frequency bands, and the radio strength of the neighboring cell belonging to a different network system from the current cell It includes inter-system measurements to measure.

According to an embodiment of the present invention, when the terminal performs the measurement on the adjacent cells in the frequency in step 313, when it is confirmed that there exists a neighboring cell having a better radio strength than the current serving cell, the process proceeds to step 321. The measurement report by the measurement report event is transmitted to the E-RAN. In response to the measurement report, driving of a timer (Measurement Stop Timer) is started.

Here, the measurement report may include information such as cell ID information indicating a cell having a radio strength better than a serving cell, a measurement result value of the cell, a serving cell ID, and a measurement result value of a serving cell. have.

The timer includes a handover for receiving a handover command (HANDOVER COMMAND) which is instructed to perform a handover to a target cell included in the measurement report of the terminal, that is, performing a handover to the target cell. Receive wait timer for receiving a command (HANDOVER COMMAND).

If the terminal receives a handover command to the target cell before the timer expires in step 323, the terminal proceeds to step 331 and performs handover as instructed.

On the other hand, if the handover command to the target cell is not received before the timer expires in step 323, the controller proceeds to step 333 to terminate the timer and the target cell corresponding to the measurement report in step 321. Stop the measurement.

The terminal includes the target cell in better cell context information. The Better cells context information includes a list of cells having a better radio intensity than an actual serving cell or cells which have stopped the measurement because the terminal has not received a handover command from the E-RAN.

That is, the terminal includes the target cell stopped in the better cells context when stopping the measurement for the cell, and if the re-measurement for the stopped cell is performed later, the target cell in the better cells context. Delete it.

After the step 333, the terminal returns to step 311 and continues to perform the measurement for the other adjacent cells in the same frequency except the cell stopped in step 333.

On the other hand, in step 313, the terminal confirming that there is no adjacent cell of radio strength better than the serving cell proceeds to step 341.

In step 341, the terminal checks whether it receives a re-measurement indication from the E-RAN for a cell included in its better cells context.

If the re-measurement instruction is received, step 351 is reached. In step 351, the terminal restarts the measurement for the cell included in the re-measurement instruction of step 341. At this time, the cell performing the re-measurement is deleted from the better cells context.

4 is a block diagram showing the structure of a terminal according to the present invention.

Referring to FIG. 4, the terminal includes a measurement performing unit 401 for neighboring cells, a management unit 411 for managing neighboring cells as a measurement target, a controller 431 for controlling a timer for a set time, and a measurer. It includes a transceiver 421 for transmitting and receiving a control message associated with the message.

First, the measurement execution unit 401 is connected to the management unit 411 through the interface to determine which adjacent cells to perform the measurement, based on the information identified by the measurement for the adjacent cells Perform.

According to the result of the measurement performed by the measurement execution unit 401, if a measurement report event occurs, that is, if the adjacent cell having a better radio strength than the serving cell is identified, the transmission and reception unit 421 ) To the E-RAN.

At this time, the timer controller 431 starts driving the timer. If the handover command for instructing handover from the E-RAN to the corresponding target cell included in the measurement report is not received until the timer expires, the management unit 411 may target the target cell. Exclude from. If the target cell is excluded from the measurement object by the manager 411, the excluded target cell is included in a better cells context.

The measurement performing unit 401 performs a measurement on adjacent cells in frequencies other than the target cell of the management unit 411.

Subsequently, when the re-measurement instruction message is received through the transceiver unit 421, the measurement execution unit 401 may display a cell corresponding to the re-measurement instruction in a better cells context of the management unit 411. Check if it is included. When it is confirmed that the cell is included, the cell is deleted from the better cells context of the management unit 411, and the cell is included in the measurement target.

Accordingly, the measurement performing unit 401 may resume the measurement for the cell.

5 is a signal flow diagram illustrating an operation procedure of an E-RAN according to the present invention.

Referring to FIG. 5, in step 501, the E-RAN receives a measurement report according to the result of the measurement from the terminal.

In step 511, it is checked whether the terminal can be handed over to the corresponding target cell corresponding to the measurement report in step 501. If possible, the flow proceeds to step 521 to perform the related handover procedure of the terminal. That is, a handover command is sent to the terminal. In operation 523, the context-related context information for the terminal is updated. That is, the serving cell of the terminal is converted into the target cell and the better cells list is initialized.

On the other hand, if the handover to the corresponding target cell corresponding to the measurement report in step 501 is not possible in step 511, the method proceeds to step 531 and does not perform the related handover procedure. In this case, the reason why the handover to the target cell is not possible is that there is a network load, that is, a load load on the target cell exists. Therefore, the E-RAN determines that it cannot handover to the target cell.

In operation 533, the E-RAN updates measurement related context information for the terminal. That is, the serving cell of the terminal is maintained but the target cell is included in the better cells.

6 is a flowchart illustrating another procedure of the E-RAN according to the present invention. 6 is an E-RAN signal flow diagram when a cell / network state is changed to perform handover again for a target cell for which handover could not be performed in response to the measurement report of FIG. 5.

Referring to FIG. 6, in step 601, the E-RAN detects a state change of a cell / network. For example, this is a case where the loaded state of a cell is changed to an unloaded state.

In step 603, the E-RAN checks the previous state for the cell where the change occurred.

In step 605, if the change from the previous state of the target cell to the current state changes from a cell in which handover is not possible to a cell capable of handover, the flow proceeds to step 621.

In step 621, the E-RAN checks whether there is a terminal including the cell of step 601 in a better cells context among active mode terminals. If so, the method proceeds to step 631 and transmits a re-measurement instruction corresponding to the cell of step 601 to corresponding terminals including the cell of step 601 in the better cells context. In this case, the re-measurement indication message may include a cell identifier of a corresponding cell to perform re-measurement.

Thereafter, in step 633, the E-RAN receives a measurement report from the corresponding terminals.

On the other hand, if the handover is not changed from impossible to possible in the cell of step 601 in step 605, or if there is no terminal to include in the better cells list of the cell of step 601 of the current active mode terminal in step 621, Take no action

7 is a diagram illustrating a structure of an E-RAN according to the present invention.

Referring to FIG. 7, the E-RAN includes a control message transmission / reception unit 711, a cell management unit 721, a radio resource management unit (hereinafter referred to as RRM) 731, and a handover execution unit 741. ).

The measurement related control message transceiver 711 receives a measurement report on the measurement procedure from the terminal.

The management unit 721 manages serving cells and better cells configured for each terminal in response to the measurement report. The management unit 721 checks whether there is another cell having a better radio strength, that is, a target cell, with respect to the current serving cell of the terminal that transmitted the measurement report.

The RRM 731 refers to the management unit 721 to check whether the terminal that has performed the measurement report can handover to the corresponding target cell. The RRM 731 is a functional block for managing information about radio resources in a cell and between cells. The RRM 731 may exist in an E-RAN according to the present invention or may exist as another physical node.

At this time, if the RRM 731 determines that handover to the target cell is possible, the RRM 731 performs a handover procedure through the handover performing unit 741.

The control message transceiver 711 transmits a handover command to the target cell.

On the other hand, if the terminal is unable to handover to the target cell, the control message transceiver 711 does not need to transmit the handover procedure and handover command to the terminal. The control message transmission / reception unit 711 includes the destination cell in correspondence with the terminal in a better cells context of the management unit 721.

When the RRM 731 finds out that handover is possible again with respect to the target cell, the RRM 731 transmits a re-measurement instruction to corresponding terminals including the target cell with reference to the better cells context of the management unit 721. To do this. The measurement instruction is transmitted to the corresponding terminals through the control message transceiver 711.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention is to define an event supporting the handover of the active mode terminal to the 3GPP LTE system.

In addition, the present invention provides the effect of minimizing the power consumption of the terminal in performing the measurement (measurement) for the neighbor cell in the 3GPP LTE system.

In addition, the present invention by the terminal and the network node manages the context including the cell list for the measurement, the effect of efficiently performing the procedure according to the re-measurement of the terminal, and finally perform the handover efficiently To provide.

Claims (29)

In the method of adjacent cell management of an active mode terminal in a mobile communication system, Detecting, by the terminal, a measurement report event; Transmitting a measurement report message including destination cell information to an E-RAN in response to the event; Operating a timer in response to the measurement report message; If the handover command message corresponding to the measurement report message is not received from the E-RAN before the timer expires, stopping the measurement for the target cell when the timer expires; And after receiving a re-measurement indication message from the E-RAN, releasing a measurement stop for the target cell. The method of claim 1, wherein the detecting of the measurement report event by the terminal comprises: The method of measuring a neighboring cell, characterized in that the process of detecting the presence of a specific target cell having a radio strength greater than the serving cell of the terminal. The method of claim 2, wherein the detecting of the measurement report event by the terminal comprises: And determining, by the terminal, that a specific target cell having a radio strength greater than that of the serving cell exists in the same frequency band as the serving cell. The method of claim 2, wherein the detecting of the measurement report event by the terminal comprises: And determining, by the terminal, that a specific target cell having a radio strength greater than that of the serving cell exists in a frequency band different from that of the serving cell. The method of claim 2, wherein the detecting of the measurement report event by the terminal comprises: And detecting, by the terminal, that a specific target cell having a radio strength greater than that of the serving cell exists in another system node that is different from the system node controlling the serving cell. The method of claim 1, wherein the measurement report message, And a message including at least one of a cell identifier for the target cell, a measurement result value for the target cell, a cell identifier for the current serving cell, and a measurement result value for the current serving cell. Cell measurement method. The method of claim 1, wherein the terminal, If the handover command message corresponding to the measurement report message is not received from the E-RAN before expiration of the timer, detecting that a handover cannot be performed to the target cell; Including the destination cell corresponding to the event in a cell list including specific cells having a radio strength better than the serving cell managed by the terminal; And receiving a message requesting a re-measurement instruction from the E-RAN, and then managing the cell list by deleting the target cell from the cell list. The method of claim 1, wherein the terminal, Receiving a measurement stop request message corresponding to the measurement report message from the E-RAN before the timer expires; And suspending the measurement for the target cell during the time information included in the measurement stop request message and performing the measurement again. The method of claim 8, wherein the measurement stop request message, And a message including a cell identifier for suspending the measurement and the time information which is a second timer value for suspending the measurement. The method of claim 1, wherein the terminal, After receiving a re-measurement indication message from the E-RAN, releasing a measurement stop for the target cell; And transmitting a measurement report message corresponding to an event indicating that the radio strength of the target cell is smaller than the serving cell to the E-RAN. A method for handing over an active mode terminal by an E-RAN in a mobile communication system, Receiving a measurement report message including destination cell information corresponding to a measurement report event from the terminal; Determining a handover state by checking a load state of the target cell; If it is determined that handover to the target cell is not possible, including the target cell in a cell list including specific cells having a better radio intensity than a serving cell of each terminal configured for each terminal; , If it is confirmed that handover is possible to the target cell, transmitting a re-measurement indication message to the terminal; Receiving a measurement report message including a measurement result value for the target cell from the terminal, and then transmitting a handover command message. The method of claim 11, If it is determined that handover to the target cell cannot be made, the method further comprises the step of transmitting a measurement stop request message including a cell identifier of the target cell and time information for pausing the measurement to the terminal. Handover method. In the handover method in a mobile communication system, A step in which the terminal connected to a serving cell and a radio access control (RRC) connection detects that the radio strength of a specific neighboring cell adjacent to the serving cell is greater than the serving cell and reports the measurement to a radio access network (E-RAN) Waiting for a handover command to be received for a timer time set in response to the measurement report from the E-RAN; terminating the measurement for the neighbor cell when the timer expires; The E-RAN transmits a re-measurement indication message for the neighboring cell to the terminal so that the terminal performs the measurement for the neighboring cell again, and receives a measurement report from the terminal again to receive the neighboring message. Handover method comprising the step of handover command to the cell. The terminal of claim 13, wherein the terminal comprises: And updating the neighboring cell in response to the measurement report in a cell list of a service context including neighboring cells with a greater radio strength adjacent to the serving cell. The method of claim 14, wherein the terminal, And upon receiving the re-measurement indication message from the E-RAN, deleting the neighbor cell from the cell list. The method of claim 13, wherein the E-RAN, And managing a context including a serving cell for each terminal and a cell list adjacent to the serving cell and adjacent cells having a greater radio strength. The terminal of claim 13, wherein the terminal comprises: And receiving a message for requesting a re-measurement indication for the neighboring cell from the E-RAN through a dedicated channel. The terminal of claim 13, wherein the terminal comprises: Receiving a message for requesting a re-measurement indication for the neighbor cell from the E-RAN through a common channel. The terminal of claim 13, wherein the terminal comprises: And receiving a measurement stop indication message from the E-RAN including a cell identifier to stop the measurement and timer information indicating the measurement stop period. A terminal device for handover in a mobile communication system, A management unit configured to manage a serving cell connected to a radio access control (RRC), a neighboring cell having a radio strength greater than that of the serving cell, in a cell list, and A measurement performing unit configured to measure a radio intensity of the serving cell and a radio intensity of the neighboring cells, detect a measurement report event, and perform a measurement on the specific neighboring cell for a predetermined timer; A transmission and reception unit which transmits a measurement report message to an E-RAN in response to the measurement report event, and waits to receive a handover command message for a predetermined time in response to the measurement report message; And a timer controller for providing time information for receiving the handover command message. The method of claim 20, wherein the measurement performing unit, And detecting the event by confirming that a radio strength of a specific neighboring cell is greater than that of the serving cell. The method of claim 20, wherein the transceiver unit, The measurement report including at least one of a cell identifier of the specific neighbor cell, a measurement result value of the specific neighbor cell, a cell identifier of the serving cell, and a measurement result value of the serving cell And generates a message and transmits the message to the E-RAN. The method of claim 20, wherein the transceiver unit, And receiving a message for requesting a re-measurement indication for the specific neighbor cell from the E-RAN. The method of claim 20, wherein the management unit, And receiving a message for requesting a re-measurement instruction for the specific neighbor cell from the E-RAN and deleting and managing the specific neighbor cell from the cell list. The method of claim 20, wherein the transceiver unit, And receiving a message for requesting stop of a message corresponding to the measurement report message from the E-RAN during the predetermined time. The method of claim 25, wherein the transceiver unit, And receiving the measurement stop request message including a cell identifier of a specific neighbor cell to stop the measurement and timer information indicating the measurement stop period. The method of claim 26, wherein the measurement performing unit, And receiving a message for requesting the stop of the message and suspending the message for the specific neighbor cell according to the timer information. A network device for instructing handover in a mobile communication system, A transceiver for receiving a measurement report message including target cell information from a specific terminal in response to a measurement report event, and generating and transmitting a handover command message to the target cell in response to the measurement report message; In response to the measurement report message, a cell list including information on a serving cell and neighboring cells having a radio strength greater than that of the serving cell is managed for each terminal, and the cell list is updated according to a handover decision to the target cell. The cell management unit, A radio resource management unit for determining whether to handover the terminal to a specific neighbor cell in response to the measurement report message; And a handover performing unit for handing over the terminal to the target cell. The method of claim 28, wherein the transceiver unit, And if it is determined that handover to the particular neighbor cell is not possible, generating a message stop indication message for stopping the measurement for the target cell and transmitting the message to the terminal.

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