KR20100005311A - System and method for controlling handover signaling of terminal with the mobile pattern which is repetitive - Google Patents

Abstract

PURPOSE: A system and a method for controlling handover of a terminal with a repetitive mobile pattern in a mobile communication network are provided to configure an adjacent cell list by majorly a cell list measured by a cell with a superior signal, thereby reducing handover and message overhead. CONSTITUTION: A UTRAN(UMTS Terrestrial Radio Access Network)(40) is composed of a plurality of RNCs(Radio Network Controllers)(30) and a plurality of node Bs(20). The UTRAN connects a mobile communication terminal(10) with a core network(50). The RNCs assigns and manages wireless resources of the node B. The node Bs actually offer wireless resources.

Description

SYSTEM AND METHOD FOR CONTROLLING HANDOVER SIGNALING OF TERMINAL WITH THE MOBILE PATTERN WHICH IS REPETITIVE}

The present invention relates to a handover control system and a method for a terminal having a certain movement pattern in a mobile communication network, and more particularly, a subscriber (eg, a subscriber having a constant movement pattern in a UMTS Terrestrial Radio Access Network (UTRAN) of a UMTS system). At the time of handover of a terminal having a fixed mobile station or a call mainly made in a specific place), a handover and message overhead are formed by forming a neighbor cell list mainly on a cell list in which a signal is measured as a best cell. The present invention relates to a handover control system and a method for reducing the number of times.

In general, a mobile communication system processes a call by allocating a call channel to a mobile communication terminal (UE) existing in its sector, where a mobile station is assigned a call channel during a call (Node-B). It often occurs that other base stations move to cells or sectors under their jurisdiction. Therefore, the neighboring base station allocates a new channel instead of the radio frequency channel in use so that the call can be maintained continuously, that is, performs a handover function.

In the mobile communication system as described above, several base stations (Node Bs) are connected to one Radio Network Controller (RNC), and each base station is composed of several cells. Here, the RNC plays a role of resource control by controlling several base stations. The mobile communication terminal (UE) may make a call by setting up one or more calls while passing through an inter-cell overlapping area, in which case a handover occurs.

For example, the UMTS Terrestrial Radio Access Network (UTRAN) of the UMTS system, which is a third generation mobile communication system based on GSM and uses Wideband Code Division Multiple Access (CDMA), is connected with a Radio Network Controller (RNC). Neighbor cell information to be handed over is exchanged between the UEs through a radio resource control (RRC) message, and the terminal hands over based on this information to provide a service without disconnection even when the terminal moves.

Here, the measurement control message transmitted from the RNC to the terminal includes a neighbor cell list, an event ID, and the like. In addition, a measurement report message transmitted from the terminal to the RNC includes an event ID. The UE performs cell measurement based on the neighbor cell list received through the measurement control message, and transmits an Event ID to the RNC through a measurement report message of an event trigger method.

Referring to FIG. 1, the problem of the handover control process according to the prior art will be described.

When the RNC receives a Radio Bearer Setup Complete message from the UE (101), the RNC sends an Event ID and a neighbor cell list to a measurement control message. It transmits to the mobile terminal (102).

In the case of FDD cells, the RNC normally adds Event 1a [Handover by Ec / Io relative value], Event 1b [Handover by Ec / Io relative value], Event 1c [Changes inactive cell and active cell], When the UE requests Event 1d [Change to Best Cell] (102), and the UE uploads the measurement report message to the RNC based on the information (103,107,111,115), the RL Addition / Deletion and Primary Cell Change A handover procedure is performed (104, 108, 112, 116). Then, it compares with the previously transmitted neighbor cell list and combines the changed parts again (105, 109, 113, 117) and delivers them to the terminal through the measurement control message (106, 110, 114, 118). That is, each time the RNC receives a measurement report message such as Event 1a, 1b, 1c, 1d from the terminal, the RNC performs a handover, and then the neighbor cell list that is already combined with the neighboring cell list that is transmitted based on the current primary cell is different. In this case, the neighboring cell list is combined only with the changed part, and the changed information is inserted into the intra-frequency cell information list (10.3.7.33 of 3GPP TS 25.331) in the measurement control message and transmitted to the terminal.

As described above, in the conventional handover control method, when the neighbor cell list previously sent to the terminal when the RL Addition, RL Deletion, and Primary Cell Change is different from the neighbor cell list combined based on the current Primary Cell, the changed part is included in the measurement control message. Sent to. However, whenever the RNC transmits a measurement control message to the terminal whenever the neighbor cell list is changed in this manner, it causes a increase in the CPU load of the RNC itself. In addition, even if the mobile station maintains a certain pattern, the subscriber's terminal transmits unnecessary measurement control messages to the terminal, thereby increasing the CPU load of the RNC. Therefore, unnecessary measurement is performed to perform a handover to an unnecessary cell. Is increased.

An object of the present invention is to provide a good signal when handover of a mobile station (e.g., a subscriber having a constant mobile location or a call mainly made at a specific place) showing a certain movement pattern in a wireless access network (UTRAN) of a UMTS system. The present invention provides a handover control system and method capable of reducing handover and message overhead by constructing a neighbor cell list around a cell list measured as a cell.

In accordance with one aspect of the present invention, a handover control system and method of an RNC that can reduce handover overhead and message overhead are disclosed. According to the present invention, in the inter-cell handover of the terminal, the RNC adds an event to store the 'best cell with the most recent signal' in the measurement control message, and designates the number of the best cells to transmit to the terminal. do. When the terminal reenters a cell previously handed over, the RNC receives a 'list of best cells previously stored in the terminal (best cell list)' according to an event through a measurement report message from the terminal and includes a neighbor including the best cell list. Construct a cell list. Here, the terminal stores the best cell as many as the number of storages, and transmits the best cell list to the RNC through a measurement report message in response to the measurement control message of the RNC.

In accordance with another aspect of the present invention, a handover control system and method of a terminal capable of reducing handover overhead and message overhead are disclosed. According to the present invention, in the inter-cell handover of the terminal, the terminal receives an event for allowing the terminal to store a 'cell (best cell) having the most recent signal' and a measurement control message in which the number of the best cells is stored. . When the terminal reenters a cell previously handed over, the terminal stores the number of best cells as many as the number of storages, and corresponding to the measurement control message of the RNC, 'the list of the best cells previously stored in the terminal according to the event (best cell list). 'Is sent to the RNC via a measurement report message to construct a neighbor cell list. In this case, the RNC adds an event to a measurement control message and specifies the number of storages to be transmitted to the terminal during inter-cell handover, and measures the best cell list from the terminal when the terminal reenters a cell previously handed over. Received through the report message, the neighbor cell list is configured including the best cell list.

According to the present invention, in particular, the UTRAN forms a neighbor cell list mainly for cells measured as a best cell for a specific subscriber station showing a certain movement pattern, and sends them to the UE, thereby reducing unnecessary handovers and causing frequent handovers. The CPU load of the RNC can be reduced by reducing the overhead and reducing the number of UE transmissions of measurement control messages due to frequent changes of the neighbor cell list.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in the following description, when there is a risk of unnecessarily obscuring the gist of the present invention, a detailed description of well-known functions and configurations will be omitted.

2 is a diagram schematically illustrating a configuration of a radio access network (UTRAN) of a UMTS system to which the present invention is applied.

The UMTS system is configured to be organically connected between a mobile communication terminal (UE) 10, a radio access network (UTRAN) 40, and a core network (for example, a GSM-MAP Core Network) 50. It is composed of a plurality of radio access networks (UTRAN) 40 connected to the core network (CN) (50).

In FIG. 2, "Iu" is an interface between the core network 50 and the radio access network 40, "Iur" is a logical interface between the radio network controller (RNC) 30 of the radio access network 40, and "Iub" represents an interface between the radio network controller 30 and the Node B 20, respectively. In addition, "Uu" represents a radio interface between the radio access network 40 and the mobile communication terminal (10). Here, Node B 20 is a logical node responsible for radio transmission and reception from or to terminal 10 in one or more cells.

The radio access network (UTRAN) 40 includes a plurality of radio network controllers (RNCs) 30 and a plurality of Node Bs 20 to connect the mobile communication terminal 10 to a core network 50. . There may be a plurality of cells below the Node B 20, and each RNC 30 controls the corresponding Node Bs 20, and each Node B 20 has a corresponding lower cell. Control them. The RNC 30 and the Node B 20 controlled by the RNC 30 and the cells are collectively referred to as RNS (Radio Network Subsystem).

The RNC 30 allocates or manages radio resources of the Node Bs 20 that it controls, and the Node B 20 serves to provide actual radio resources. Radio resources are configured for each cell, and radio resources provided by the Node B 20 refer to radio resources of cells managed by itself. Each Node B 20 manages one or more cells and is connected to the RNC 30 via an Iub interface. The RNC 30 performs the combination / splitting function during the handover between the Node Bs 20, and in the case of the inter-cell handover in the same Node B 20, the RNC 30 may perform the Combining / Splitting function. B 20 may do this. The terminal 10 may configure a radio channel and perform communication using radio resources provided by a specific cell of a specific Node B 20. From the standpoint of the terminal 10, the distinction between the Node B 20 and the cell is meaningless, and since only the physical layer configured for each cell is recognized, the Node B 20 and the cell will be referred to as the same meaning hereinafter.

In the UTRAN 40 having the above-described configuration, the terminal 10 of the subscriber having a certain movement pattern (for example, a subscriber having a constant mobile location or an address call at a specific place) has a predictable movement path. In the present invention, the terminal 10 constructs a neighbor cell list mainly on 'cell lists used mainly' (i.e., best cell list) and sends them to the terminal 10 for unnecessary handover. The CPU burden of the RNC 30 can be reduced by reducing the number of times of transmitting the measurement control message to the terminal 10 due to frequent changes of the neighbor cell list.

To this end, the RNC 30 selects "Event 1k" [List of the latest best cells (FDD only)] as shown in Table 1 (Intra-frequency measurement reporting criteria) below. In addition to the event, the terminal 10 by adding the "Amount of best cell list for saving" field (defined in FIG. 6 for this field value) as shown in FIGS. 5A and 5B to the measurement control message of the 25.331 RRC spec. To send. Then, whenever the "Event 1d" (change to the best cell signal) occurs, the terminal 10 is the 'cells with the most recent signal (the set of these cells is the best cell list) Is stored as much as "Amount of best cell list for saving" of the measurement control message, and when the event 1k request is received from the RNC 30 as the measurement control message, the measurement report message of 25.331 RRC spec as shown in FIG. The previously stored best cell list is reported to the RNC 30 by using the "Saved Intra-frequency Best Cells" newly added to the.

In this case, the best cell list is a set of cells handed over by the terminal 10 of a subscriber having a certain movement pattern (for example, a subscriber having a fixed mobile location or an address call at a specific place). . For example, suppose there are three paths from point A to point B (path a, path b, path c), and any subscriber A primarily uses path a and subscriber B primarily uses path c. Suppose that cell 1, cell 2, and cell 3 are arranged on path a, and the subscriber A's terminal is handed over from "cell 1-> cell 2-> cell 3". Cell List) becomes " (Cell 1, Cell 2, Cell 3) ". In addition, when cell 1, cell 4, and cell 3 are arranged on the path c and the terminal of the subscriber C hands over from "cell 1-> cell 4-> cell 5-> cell 3", the best cell list of the subscriber C (Best Cell) List) becomes " (cell 1, cell 4, cell 5, cell 3) ". For example, for subscriber A, the best cell list of {cell 1, cell 2, cell 3} is reported to RNC 30 in "Saved intra-frequency cells" of the measurement report message of FIG. The best cell list of cell 1, cell 4, cell 5, and cell 3} is reported to RNC 30 in "Saved intra-frequency cells" of the measurement report message of FIG.

Here, the maximum number of best cells (maxSaveBestCellList) included in the best cell list may be arbitrarily selected by the RNC operator. That is, "maxSaveBestCellList" is a value that determines how many RNC operators include a neighbor cell list of 'best cells with the most recent signals' stored in the terminal 10. This value can be set through the Operations and Management Console for Radio (OMC-R), which performs the function of giving the operator the necessary information to the RNC 30, according to this value, the terminal 10 is a cell having excellent signal Save the Best Cell. That is, when "maxSaveBestCellList" is 3, up to 3 best cells are stored.

The best cell of the best cell list is configured with a primary scrambling code (PSC) value, and the best cell list is maintained even when the terminal 10 releases a call or turns off the power. .

Intra - frequency measurement reporting criteria The triggering of the event-triggered reporting for an intra-frequency measurement. All events concerning intra-frequency measurements are labeled 1x where x is a, b, c… . Event 1a: A Primary CPICH enters the Reporting Range (FDD only). Event 1b: A Primary CPICH leaves the Reporting Range (FDD only). Event 1c: A Non-active Primary CPICH becomes better than an active Primary CPICH (FDD only). Event 1d: Change of best cell (FDD only). Event 1e: A Primary CPICH becomes better than an absolute threshold (FDD only). Event 1f: A Primary CPICH becomes worse than an absolute threshold (FDD only). Event 1g: Change of best cell in TDD. Event 1h: Timeslot ISCP below a certain threshold (TDD only). Event 1i: Timeslot ISCP above a certain threshold (TDD only). Event 1k: List of the latest best cells ( FDD only ).

Meanwhile, the RNC 30 configures a neighbor cell list based on the best cell list. At this time, the maximum number of all cells (macNeighborListSizeIntraFreq) constituting the neighbor cell list may also be arbitrarily selected by the RNC operator, and this value may be set in the OMC-R.

In the above, "macNeighborListSizeIntraFreq" is preferably "maxSaveBestCellList" or more. Accordingly, the neighbor cell list is configured to include the best cell list, but the neighbor cells of the corresponding cell are filled with the remaining cells except the best cell list by the difference between "macNeighborListSizeIntraFreq" and "maxSaveBestCellList". For example, when configuring the neighbor cell list of cell 4, assuming that "macNeighborListSizeIntraFreq" is 4 and "maxSaveBestCellList" is 3, all of the best cell lists (eg, {cell1, cell2, cell3}) and cells Any one of the neighboring cells of 4 (assuming, for example, cell 5, cell 1, and cell 7) (which becomes either cell 5 or cell 7 except for nested cell 1) is selected, and the neighbor cell list Becomes {cell1, cell2, cell3, cell5 (or cell7)}.

3A and 3B are flowcharts illustrating a handover control method in a mobile communication system according to an embodiment of the present invention. In order to help understanding, it will be described with reference to Figure 4 as an example.

First, assume that the movement path of the terminal 10 is equal to "cell 1-> cell 2-> cell 3-> cell 3-> cell 2-> cell 1".

The RNC 30 receives a "maxSavedBestCellList" value and a "maxNeighborListSizeIntraFreq" value set by the RNC operator from the OMC-R (301). In this case, the "maxSaveBestCellList" is a value that determines how many neighbor cells list to include the 'most recent best cell (cell) with the most recent signal stored in the terminal 10, for example' Assume 3 '. In addition, "maxNeighborListSizeIntraFreq" is a value for determining the maximum number of all cells constituting the neighbor cell list. For example, assume "4 (Range 0 to 32)".

For the handover control of the present invention, when the RNC 30 receives a radio bearer setup complete message from the terminal 10 (302), Event 1k through a measurement control message (see FIGS. 5A and 5B). In operation 303, the UE 10 transmits the list of the best cells (ie, the best cell list) and the neighbor cell list to the terminal 10 (step 303). At this time, in case of FDD cell, Event 1a [Handover Add by Ec / Io Relative Value], Event 1b [Handover Drop by Ec / Io Relative Value], Event 1c [Change of Deactivated Cell and Activated Cell], Event 1d (Change to Best Cell) is required. Here, the field value "Amount of best cell list for saving (maxSavedBestCellList)" is added to the measurement control message, and a value other than '1' is assigned to the field value. The terminal 10 does not store the best cell list when the value of the "Amount of best cell list for saving" field is '1'.

Here, the neighbor cell list transmitted by the RNC 30 to the terminal 10 after completion of radio bearer setup is configured with neighbor cells of the corresponding cell set to a default value. For example, cell 1 is "PSC 35", cell 2 is "PSC 16", cell 3 is "PSC 100", cell 4 is "PSC 27", cell 5 is "PSC 77", and cell 6 is "PSC 2". Suppose that cell 7 is "PSC 3", cell 8 is "PSC 4", cell 9 is "PSC 5", cell 10 is "PSC 64", and cell 11 is "PSC 108". Then, as shown in Figure 4, the neighbor cell list of the cell 1 is the default value, {cell 5 (PSC 77), cell 6 (PSC 2), cell 7 (PSC 3), cell 2 (PSC 16)} It consists of [4a]. In addition, the neighbor cell list of Cell 2 defaults to {Cell 3 (PSC 100), Cell 1 (PSC 35), Cell 5 (PSC 77), Cell 8 (PSC 4), and Cell 9 (PSC 5)}. It is composed [4b]. In addition, the neighbor cell list of cell 3 defaults to {cell 4 (PSC 27), cell 5 (PSC 77), cell 7 (PSC 3), cell 8 (PSC 4), and cell 9 (PSC 5)}. It is constructed [4c]. In addition, the neighbor cell list of cell 4 is composed of {cell 5 (PSC 77), cell 10 (PSC 64), cell 11 (PSC 108), and cell 3 (PSC 100) by default [4d].

The terminal 10 transmits the measurement report message to the RNC 30 based on the event ID of the measurement control message of the RNC 30 (304, 307, 309, 311). In particular, in the present invention, the terminal 10 raises the event 1d ( 307, 309, and 311 store the 'best cell having the most recent signal' (306, 308, 310). This is performed according to the Event 1k request of the measurement control message, and the best cells are stored as many as the maximum number of cells included in the best cell list ["Amount of best cell list for saving (maxSavedBestCellList)"). For example, since "maxSaveBestCellList" is set to '3', up to three (cell 1, cell 2, cell 3) can be stored (306, 308, 310). That is, when the terminal 10 hands over from "cell 1-> cell 2-> cell 3", the best cells are sequentially stored [cell 1 (PSC 35)-> cell 2 (PSC 16)-> cell 3 (PSC 100). ], The best cell list is {Cell 1 (PSC 35), Cell 2 (PSC 16), Cell 3 (PSC 100)}. At this time, the best cell list stored in the terminal 10 will be reported to the RNC 30 through "Saved Intra-frequency Best Cells" (see FIG. 7) of the measurement report message. Detailed description thereof will be described later.

Here, if the measurement report message is Event 1k and there is no or one "Saved Intra-frequency Best Cells" information (304), the neighbor cell list classification algorithm of the present invention is not operated (305). That is, when there is no "Saved Intra-frequency Best Cells" information, it means that there is no list of best cells stored in the terminal 10. In the case of one, the best cell stored in the terminal 10 is one cell, without moving between cells. This means that the terminal 10 stays.

By doing so, the radio bearer setup when the terminal 10 moves from "cell 1-> cell 2-> cell 3" is completed (312).

In the above, it is assumed that the movement path of the terminal 10 is from "cell 1-> cell 2-> cell 3". Hereinafter, the movement path of "cell 4-> cell 3-> cell 2-> cell 1" of the terminal 10 will be described.

When the terminal 10 calls again and finishes the radio bearer setup complete procedure (321), the event control message (refer to FIG. 5A and 5B) (see FIG. A list of cells, that is, a best cell list] and a neighbor cell list, are transmitted to the terminal 10 (322). At this time, the neighbor cell list of cell 4 is transmitted by default (cell 5 (PSC 77), cell 10 (PSC 64), cell 11 (PSC 108), cell 3 (PSC 100)} [4d]). .

In contrast, the terminal 10 stores the best cell list {Cell 1 (PSC 35), cell 2 (PSC 16), and cell 3 (prestored) using the "Saved Intra-frequency Best Cells" of the measurement report message of FIG. PSC 100)} to the RNC 30 (323). Accordingly, the RNC 30 drives the neighbor cell list classification algorithm (324). This is because the "Saved Intra-frequency Best Cells" information is '3' and the best cell list is {Cell 1 (PSC 35), Cell 2 (PSC 16), and Cell 3 (PSC 100)}.

The terminal 10 does not store all of the corresponding best cells every time the event 1d is raised (326, 331, 334, 337) (325, 330, 333, 326). That is, it stores as much as "Amount of best cell list for saving (maxSavedBestCellList)". In the above, it is assumed that 'maxSavedBestCellList' is '3' and {cell1 (PSC 35), cell 2 (PSC 16), and cell 3 Since (PSC 100)} is stored in the best cell list, no more best cells (cell 4) are stored (325).

When the neighbor cell list classification algorithm is driven in the RNC 30 (324), when the event 1d measurement report message is received from the terminal 10 (326), the event 1k received from the terminal 10 in the neighbor cell list in the measurement control message is received. First, the best cell list (cell 1 (PSC 35), cell 2 (PSC 16), and cell 3 (PSC 100)) of the measurement report message is inserted first, and the remaining cells of the corresponding cell (cell 4) [cell 5 (PSC 77). ), Cell 10 (PSC 64), cell 11 (PSC 108), or cell 3 (PSC 100).], And the adjacent cell list is selected so that the total number of cells becomes "maxNeighborListSizeIntraFreq (= 4)". Configure and transmit to the terminal 10 (327, 328). That is, the neighbor cell list includes a best cell list transmitted from the terminal 10, but the neighbor cell of cell 4 is equal to the difference value (= 1) between "maxNeighborListSizeIntraFreq (= 4)" and "maxSavedBestCellList (= 3)". Choose one. If the difference is '2', two of the adjacent cells of cell 4 may be selected. For example, in cell 4, since "maxNeighborListSizeIntraFreq" is set to '4', all of the best cell lists {cell 1 (PSC 35), cell 2 (PSC 16), and cell 3 (PSC 100)} transmitted from the terminal 10 are all. And any one of adjacent cell lists {cell 5 (PSC 77), cell 10 (PSC 64), cell 11 (PSC 108), and cell 3 (PSC 100)} set to the default value of cell 4 (i.e., Cell 5 (PSC 77), cell 10 (PSC 64), or cell 11 (PSC 108), except for cell 3 (PSC 100), but cell 5 (PSC 77). A list of neighboring cell lists {Cell 1 (PSC 35), Cell 2 (PSC 16), Cell 3 (PSC 100), Cell 5 (PSC 77)} (4e in FIG. 4) in a measurement control message. 10) (328).

By doing so, the terminal 10 completes the radio bearer setup in " cell 4 " (329).

Referring to the case where the movement path of the terminal 10 is "cell 3-> cell 2-> cell 1", when Event 1d occurs only in the existing best cell and handover is made (cell 3-> cell 2-> cell 1), the RNC ( 30 does not transmit a measurement control message to the terminal 10 even if the event 1d measurement report message is received each time (331, 334, 337) and is identical to the previously transmitted neighbor cell list (332, 335, 338).

That is, the RNC 30 moves the cell 10 from the cell 4 to the cell 3 while the neighbor cell list classification algorithm is driven 324, and sends an Event 1d (cell 3) measurement report message from the terminal 10. Even when receiving (331), since there is no change in the adjacent cell list {cell 1 (PSC 35), cell 2 (PSC 16), cell 3 (PSC 100), cell 5 (PSC 77)} (4f in FIG. 4), measurement control The message is not transmitted to the terminal 10 (332). Further, even if the terminal 10 moves from cell 3 to cell 2 and receives an Event 1d (cell 2) measurement report message from the terminal 10 (334), the neighbor cell list {cell 1 (PSC 35), cell 2 ( PSC 16, cell 3 (PSC 100), cell 5 (PSC 77)} is not changed (4g in FIG. 4), the measurement control message is not transmitted to the terminal 10 (335). Further, even if the terminal 10 moves from cell 2 to cell 1 and receives an Event 1d (cell 1) measurement report message from the terminal 10 (337), the neighbor cell list {cell 1 (PSC 35), cell 2 ( PSC 16, cell 3 (PSC 100), cell 5 (PSC 77)} is not changed (4h in FIG. 4), so that the measurement control message is not transmitted to the terminal 10 (338).

As such, when the terminal 10 moves to a previously moved cell, even if a new neighbor cell list is not transmitted every time, the handover fails because the neighbor cell cannot be measured. In addition, the occurrence of frequent measurement control messages can be significantly reduced.

In the above embodiment, Intra-frequency is used as an example for the measurement control message and the measurement report message, but it should be noted that the handover control technique of the present invention can be equally applied to the inter-frequency or Inter-RAT measurement. .

Although the methods have been described through specific embodiments, the methods may also be embodied as computer readable code on a computer readable recording medium. Computer-readable recording media include all kinds of recording devices that store data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, which are also implemented in the form of carrier waves (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the above embodiments can be easily inferred by programmers in the art to which the present invention belongs.

In addition, while the present invention has been described in connection with some embodiments, it is to be understood that various modifications and changes can be made without departing from the spirit and scope of the invention as will be understood by those skilled in the art. You will need to know Also, such modifications and variations are intended to fall within the scope of the claims appended hereto.

1 is a flowchart illustrating a handover control process in a mobile communication system according to the related art.

2 is a diagram schematically showing a configuration of a radio access network (UTRAN) of a UMTS system to which the present invention is applied.

3A and 3B are flowcharts illustrating a handover control method in a mobile communication system according to an embodiment of the present invention.

4 is an explanatory diagram showing a handover control process in a mobile communication system according to an embodiment of the present invention.

5A and 5B illustrate the format of a measurement control message in accordance with an embodiment of the invention.

6 is a diagram illustrating a measurement control message value according to an embodiment of the present invention.

7 illustrates the format of a measurement report message in accordance with an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

10: mobile communication terminal (UE) 20: base station (Node B)

30: radio network controller (RNC) 40: UMTS radio access network (UTRAN)

50: Core Network

Claims (18)

As a handover control system, In the inter-cell handover of the terminal, the RNC adds an event to store the 'best cell with the most recent signal' in the measurement control message, and designates the number of the best cells to transmit to the terminal, When the terminal reenters a cell previously handed over, the RNC receives a 'list of best cells (best cell list) previously stored in the terminal according to the event' from the terminal through a first measurement report message, And a neighbor cell list including a best cell list. The method of claim 1, The terminal stores the best cell as much as the storage number, and transmits the best cell list to the RNC through the first measurement report message in response to the measurement control message of the RNC. As a handover control system, In the inter-cell handover of the terminal, the terminal receives an event for allowing the terminal to store a 'cell (best cell) having the most recent signal' and a measurement control message in which the number of best cells is stored. When the terminal re-enters a cell previously handed over, the terminal stores the best cell by the number of the storage, and in response to the measurement control message of the RNC, 'the list of the best cells previously stored in the terminal according to the event ( And a best cell list) to the RNC via a first measurement report message to construct a neighbor cell list. The method of claim 3, The RNC adds the event to the measurement control message and specifies the number of storage to be transmitted to the terminal during intercell handover of the terminal, and when the terminal reenters a cell previously handed over, the best Receiving a cell list from the terminal through the first measurement report message, and constructing the neighbor cell list including the best cell list. The method according to any one of claims 1 to 4, The terminal does not store the best cell exceeding the storage number, handover control system. The method of claim 5, The terminal maintains the previously stored best cell list even when a call is released or powered off. The method according to any one of claims 1 to 4, The RNC, when constructing the neighbor cell list, includes all of the best cell lists within a configuration number range of cells included in the best cell list and fills the remaining part with some cells of neighbor cells of the corresponding cell. system. The method of claim 7, wherein And the some cells do not overlap with a best cell constituting the best cell list. The method of claim 8, Even if the RNC receives a second measurement report message regarding a best cell change from the terminal, the RNC does not transmit the currently configured neighbor cell list to the terminal when the previously configured neighbor cell list and the currently configured neighbor cell list are the same. Over control system. The method of claim 7, wherein And the configuration number and the storage number are dynamically set, and wherein the configuration number is greater than or equal to the storage number. As a handover control method of a mobile communication system, During an inter-cell handover of the terminal, adding an event to the RNC to store a 'cell (best cell) having the most recent signal' in a measurement control message, and designating a number of the best cells to transmit to the terminal; When the terminal reenters a cell previously handed over, the RNC receiving a 'list of best cells previously stored in the terminal (best cell list)' from the terminal through a first measurement report message according to the event; ; And The RNC constructing a neighbor cell list including the best cell list Handover control method comprising a. The method of claim 11, Storing, by the terminal, the number of best cells as many as the stored number, and transmitting the best cell list to the RNC through the first measurement report message in response to the measurement control message of the RNC. Handover control method further comprising. As a handover control method of a mobile communication system, Receiving an event for allowing the terminal to store a 'cell (best cell) having the most recent signal' and a measurement control message in which the number of storage of the best cells is specified from the RNC during inter-cell handover of the terminal; When the terminal re-enters a cell previously handed over, storing, by the terminal, the best cell by the number of the storage; And In response to the measurement control message of the RNC, the UE transmits a 'list of best cells (best cell list) pre-stored in the UE according to the event' to the RNC through a first measurement report message to construct a neighbor cell list. Steps Handover control method comprising a. The method of claim 13, Receiving, by the RNC, the best cell list from the terminal through the first measurement report message, and constructing the neighbor cell list including the best cell list Handover control method further comprising. The method according to any one of claims 11 to 14, The terminal does not store the best cells exceeding the storage number, and maintains the previously stored best cell list even when a call is released or powered off. The method according to any one of claims 11 to 14, When configuring the neighbor cell list, the RNC includes all of the best cell lists within the configuration number range of the cells included in the best cell list and fills the remaining portions with some of the neighbor cells of the corresponding cells. The handover control method which does not overlap with the best cell which comprises this said best cell list. The method of claim 16, Even if the RNC receives a second measurement report message regarding a best cell change from the terminal, if the previously configured neighbor cell list and the currently configured neighbor cell list are the same, not transmitting the currently configured neighbor cell list to the terminal Handover control method further comprising. A computer readable storage medium storing computer executable instructions for performing the method of any one of claims 11-14.

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