WO2012037838A1

WO2012037838A1 - Handover target cell selection method and base station controller

Info

Publication number: WO2012037838A1
Application number: PCT/CN2011/077333
Authority: WO
Inventors: 寇毅; 王海峰; 陈祥榴
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-09-21
Filing date: 2011-07-19
Publication date: 2012-03-29
Also published as: CN102413526A; CN102413526B

Abstract

A handover target cell selection method and a base station controller. The method comprises: when a base station controller is configuring neighboring cell handover data, if an intra-frequency neighboring cell is detected, then the base station controller sets one or more associated cells for the intra-frequency neighboring cell, the associated cell being an inter-frequency cell of a serving cell; the base station controller makes a handover decision according to a neighboring cell measurement report reported by a user terminal to obtain handover candidate cells, and if it is determined that an intra-frequency neighboring cell exists among the handover candidate cells, the base station controller selects a handover target cell according to the situations of the intra-frequency neighboring cell and the preset associated cell. According to the present invention, an identifier is added to a neighboring cell to indicate whether the cell is an intra-frequency neighboring cell, and an associated cell is set for an intra-frequency neighboring cell, so as to effectively decrease the possibility of handover to an intra-frequency neighboring cell, effectively decrease the number of handover drops resulting from poor downlink quality caused by interference from the intra-frequency neighboring cell, and decrease the handover drop ratio of the user terminal.

Description

Method and base station controller for selecting handover target cell

Technical field

The present invention relates to the field of inter-cell handover technology of a Global System for Mobile communication (GSM) wireless network system, and in particular, to a method and a base station controller for selecting a handover target cell.

Background technique

Due to the small number of available frequency points, it is inevitable in the network planning to configure neighboring cells of the same frequency and different colors for one cell, so that if the user terminal makes a call in the cell and performs handover, it will be affected by the same frequency interference. , causing the downlink quality to be poor after the handover and dropped calls. As shown in Figure 1, there are 5 cells in total, and the relationship between the small intervals is as follows:

The A cell is the current serving cell;

The four cells B, C, D, and E are neighbors of A;

The two cells B and C have the same frequency and different colors.

During the call of the user terminal, the current serving cell is the A cell. When moving to the area 1 or the area 2 or the area 3, the base station controller (BSC) handover decision is established, according to the neighboring area frequency in the neighboring area measurement report. The list index value and the base station identification code (BSIC) can obtain the same-frequency neighboring cell (there is only one co-frequency neighboring cell in the same measurement report, and the same-frequency neighboring cell list list index in different measurement reports) Similarly, if the BSIC is different, if the two intra-frequency neighboring levels are phase-superimposed, the level parameter value of the same-frequency neighboring area of the neighboring area measurement report in the measurement report reported by the user terminal is enhanced, and the handover decision is likely The intra-frequency neighboring cell is selected as the target cell for handover, but it is not possible to determine which co-frequency neighboring cell is selected. If the user terminal is currently in the area 1 and forwards to the B cell coverage area, the B cell should be selected as the handover target cell according to the actual plan, but the C cell is selected; or the user terminal is currently in the area 3, and the C cell coverage area is forwarded. According to the actual plan, the C cell should be selected as the handover target cell, but the B cell is selected. This will result in the neighbor cell level measured before the handover is very good. After switching to the neighbor B or C, the cell B and C are co-frequency. Interference, sudden deterioration in quality, resulting in poor quality and dropped calls. Summary of the invention

The technical problem to be solved by the present invention is to provide a method for selecting a handover target cell and a base station controller, so that in the case of a co-frequency cell, the most suitable neighboring cell is selected as the handover target cell, and the intra-frequency neighboring zone is switched. Interference, reducing the rate at which the phone switches off calls.

In order to solve the above technical problem, the present invention provides a method for selecting a handover target cell, including:

When the base station controller configures the handover neighboring area data, if it is detected that the same frequency neighboring area exists, the one or more related cells are set for the same frequency neighboring area, and the related cell is a non-co-frequency neighboring area of the serving cell; The base station controller performs a handover decision according to the neighboring cell measurement report reported by the user terminal, and acquires a handover candidate cell, and if it is determined that the same-frequency neighboring cell exists in the handover candidate cell, according to the same-frequency neighboring cell and the preset correlation The situation of the cell selects the handover target cell.

Preferably, the foregoing method further has the following features: the step of the base station controller selecting the handover target cell according to the situation of the same-frequency neighboring cell and the preset related cell includes:

If the base station controller determines that there is a co-frequency neighboring cell and a related cell corresponding to the same-frequency neighboring cell, and there is no related cell corresponding to the cell of the same-frequency neighboring cell, the cell controller selects The intra-frequency neighboring cell is used as a handover target cell.

If the base station controller determines that there is a co-frequency neighboring cell and a related cell corresponding to the co-frequency neighboring cell, and there is a related cell corresponding to the cell of the same-frequency neighboring cell, the base station controller reduces the The same frequency neighboring area is used as the priority of the handover target cell.

Preferably, the foregoing method further has the following features: after the step of detecting, by the base station controller, the same frequency neighboring area, the method further includes: the base station controller configuring an identifier for the same frequency neighboring area;

The step of the base station controller determining that the same-frequency neighboring cell exists in the handover candidate cell is: determining, by the base station controller, that the same-frequency neighboring cell exists in the handover candidate cell according to the identifier.

In order to solve the above problem, the present invention further provides a base station controller, including:

The configuration module is configured to: when the neighboring area data configuration is switched, if the same frequency neighboring area is detected, And setting one or more related cells to the same-frequency neighboring cell, where the related cell is a non-co-frequency neighboring cell of the serving cell;

An acquiring module, configured to: perform a handover decision according to a neighboring cell measurement report reported by the user terminal, to acquire a handover candidate cell;

And a selection module, configured to: if it is determined that the same-frequency neighboring cell exists in the handover candidate cell, the handover target cell is selected according to the same-frequency neighboring cell and the related cell preset by the configuration module.

Preferably, the foregoing base station controller further has the following features:

The selecting module is configured to: if it is determined that there is a co-frequency neighboring cell and a related cell corresponding to the same-frequency neighboring cell, and there is no related cell corresponding to the cell of the same-frequency neighboring cell Then, the same frequency neighboring area is selected as the handover target cell.

The selection module is configured to: if it is determined that there is a co-frequency neighboring cell and a related cell corresponding to the same-frequency neighboring cell, and there is a related cell corresponding to the cell of the same-frequency neighboring cell, Then, the intra-frequency neighboring cell is lowered as the priority of the handover target cell.

The configuration module is further configured to: configure an identifier for the same-frequency neighboring area;

The selecting module is configured to: determine, according to the identifier, that a co-frequency neighboring cell exists in the handover candidate cell.

In summary, the method for selecting a handover target cell and the base station controller provided by the embodiment of the present invention can effectively reduce the same frequency by adding whether the neighboring cell is an intra-frequency neighboring cell identifier and setting a related cell to the same-frequency neighboring cell. The possibility of the neighboring cell handover can effectively reduce the number of dropped calls of the downlink quality difference due to interference in the same frequency neighboring zone, and reduce the ratio of the dropped call rate of the user terminal. BRIEF abstract

FIG. 1 is a schematic diagram of an application scenario according to an embodiment of the present invention;

2 is a schematic diagram of a BSC according to an embodiment of the present invention; 3 is a flowchart of a method for selecting a handover target cell according to the present invention;

FIG. 4 is a flowchart of a method for selecting a handover target cell according to an embodiment of the present invention. Preferred embodiment of the invention

The core idea of the embodiment of the present invention is that, when configuring the handover neighboring cell data, the BSC sets a related cell for the same-frequency neighboring cell in advance, and determines whether the same-frequency cell is valid by the relevant cell, so as to effectively reduce the handover to the same-frequency neighboring cell. possibility.

For a better understanding of the invention, the invention will be further described in conjunction with the drawings and specific embodiments.

2 is a schematic diagram of a BSC according to an embodiment of the present invention. As shown in FIG. 2, the BSC of this embodiment includes: a configuration module, an obtaining module, and a selecting module, where

a configuration module, configured to set one or more related cells for the same-frequency neighboring cell when the neighboring cell data configuration is detected, where the related cell is a non-co-frequency neighbor of the serving cell Area;

Obtaining a module, performing a handover decision according to the neighboring area measurement report reported by the user terminal, and acquiring a handover candidate cell;

And a selection module, if it is determined that the same-frequency neighboring cell exists in the handover candidate cell, the handover target cell is selected according to the same-frequency neighboring cell and the related cell preset by the configuration module.

The BSC in this embodiment determines whether the same-frequency cell is valid through the relevant cell, so as to effectively reduce the possibility of switching to the same-frequency neighboring cell.

Further, the selecting module, if it is determined that there is a co-frequency neighboring cell and a related cell corresponding to the same-frequency neighboring cell, and there is no related cell corresponding to the cell of the same-frequency neighboring cell Then, the same frequency neighboring area is selected as the handover target cell.

If the corresponding cell is not present in the neighboring cell measurement report, the co-frequency neighboring cell is considered to be an invalid candidate cell, and the same-frequency neighboring cell is filtered out; if the user terminal has the same-frequency neighboring cell in the neighboring cell measurement report reported by the serving cell If there is a corresponding cell in the neighboring area measurement report, but there is no related cell in the neighboring cell with the same frequency in the same-frequency neighboring cell, then the same-frequency neighbor reported by the user terminal is reported. A zone is a valid candidate cell and can serve as a handover target cell.

Further, the selecting module, if it is determined that there is a co-frequency neighboring cell and a related cell corresponding to the co-frequency neighboring cell, and a related cell corresponding to the neighboring cell of the same-frequency neighboring cell And selecting a non-co-frequency neighboring cell in the handover candidate cell as the handover target cell.

Further, the configuration module is further configured to configure an identifier for the same-frequency neighboring cell;

The selecting module is specifically configured to determine, according to the identifier, that a co-frequency neighboring cell exists in the handover candidate cell.

If the related cell of the same-frequency neighboring cell exists, but there is also a related cell of the neighboring cell with the same frequency, the candidate cell of the same-frequency neighboring cell is reduced as the priority of the handover target cell, and the candidate cell of the non-co-frequency neighboring cell is preferentially selected. As the handover target cell.

FIG. 3 is a flowchart of a method for selecting a handover target cell according to an embodiment of the present invention. As shown in FIG. 3, the method in this embodiment includes the following steps:

Step 10: When the BSC is configured to switch the neighboring cell data, if the same-frequency neighboring cell is detected, the BSC sets one or more related cells for the same-frequency neighboring cell, where the related cell is a non-co-frequency neighboring cell of the serving cell. ;

Step 20: The BSC performs a handover decision according to the neighboring cell measurement report reported by the user terminal, and obtains a handover candidate cell. If it is determined that the same-frequency neighboring cell exists in the handover candidate cell, the BSC is configured according to the same-frequency neighboring cell and the preset related cell. The situation selects the handover target cell.

When the handover decision is made, the BSC obtains the handover candidate cell based on the original handover decision method, and then determines whether the candidate cell is a co-frequency neighboring cell according to the identifier of the same-frequency neighboring cell, and if it is the same-frequency neighboring cell, the related cell needs to be further used. It is determined whether the candidate cell is valid. If the co-frequency neighboring cell is invalid, the candidate cell is filtered and filtered, which can greatly avoid the possibility that the downlink quality deteriorates and the call drop after the handover is caused by the same-frequency interference, and the mobile phone switching dropped call rate is reduced.

You can configure one related cell for the same-frequency neighboring cell or multiple related cells. This is mainly based on the actual actual environment of the site.

The technical solution is illustrated by taking the example scenario of FIG. 1 as an example. Assume that in the scenario of Figure 1, one relevant cell is configured in the same-frequency neighboring cell, and the relationship among the five cells A, B, C, D, and E is as follows:

The four cells lB, C, D, E are neighbors of the A cell; 2. The A cell is the current serving cell;

3. The B cell and the C cell are cells of the same frequency and different colors;

4. The relevant cell of the B cell is a D cell, and the related cell of the C cell is an E cell.

When the user terminal moves to one of the area 1, the area 2, or the area 3, the BSC calculates that the mobile phone satisfies the handover condition by using the measurement report reported by the mobile phone user terminal, and finds that the C, D, and E cells can be used as the handover by measurement and calculation. The candidate cell, the same-frequency neighboring area is superimposed by the level to make the level value the largest, and the user terminal cannot determine that the neighboring area decoded in the current area is the neighboring area that the user terminal is expected to detect and decode in the area during network planning, and the neighboring area is reported. The area measurement report is sent to the BSC, and the BSC determines whether the handover candidate cell is a co-frequency neighboring cell by using the identifier of the same-frequency neighboring cell. Here, it is assumed that the same-frequency neighboring cell B, the BSC can be based on the BSIC and the neighboring cell list of the same-frequency neighboring zone B. The index value obtains the relevant cell D of the same-frequency neighboring cell B, and the BSIC and neighbor cell list index values of the neighboring cell E of the BSIC and C of the same-frequency neighboring cell C. The BSC traverses all the neighboring cell information in the neighboring cell measurement report. If there is a BSIC and a neighboring cell point list index value of the neighboring cell that matches the D cell in the neighboring cell measurement, there is no neighboring cell that matches the E cell. The BSIC and the neighboring cell list index value, the co-frequency neighbor B can be used as the handover target cell; if there is no BSIC and neighbor cell list index value of the neighbor cell matching the D cell, it is considered as a user terminal error. Reporting, the co-frequency neighboring cell candidate cell does not serve as a handover target cell; if there is a BSIC and a neighbor cell frequency point list index value of a neighboring cell that matches the D cell, but also there is a BSIC and a neighbor of the neighboring cell that matches the E cell. If the regional frequency point list index value is used, the intra-frequency neighboring cell candidate cell B is reduced as the priority of the handover target cell, and the non-inter-frequency neighboring cell D or E is preferentially selected as the target cell for handover.

In the real network environment, in many places, due to the small number of available frequency points, it is necessary to configure the same-frequency neighboring area in the network planning, and the network environment is caused by the instability of the wireless network and the complex geographical environment. In some places, repeated coverage of the same frequency cell occurs, and the user terminal switches at these locations. Due to the interference of the same frequency signal, the quality of the call is greatly affected, and the downlink quality suddenly changes after the handover, which makes the possibility of dropped calls very large. . Voice quality, switching call drop ratio is an indicator that operators pay great attention to, so the invention has great application value.

A new method for selecting a handover target cell according to an embodiment of the present invention optimizes a handover decision method of a BSC, and does not modify a flow of implementing the BSC control handover function. The invention adds the means for determining whether the candidate cell is a co-frequency neighboring cell and a related cell of the same-frequency neighboring cell, and uses the means to filter out the user end. The same frequency neighboring area of the false alarm, or the related cell of the same frequency neighboring area in the neighboring area measurement report, and the same frequency neighboring area candidate cell of the related cell of the same frequency neighboring area as the handover target cell Priority, which can greatly reduce the user terminal's mis-switching due to co-channel interference, and the quality of the call suddenly deteriorates and the call is dropped.

FIG. 4 is a flowchart of a method for selecting a handover target cell according to an embodiment of the present invention. As shown in FIG. 4, the steps are as follows:

Step 101: The BSC obtains the number of candidate cells and candidate cells according to the original decision process.

Step 102: Perform corresponding processing according to the number of candidate cells. If the number of candidate cells is 0, the process proceeds to step 107, the handover decision ends, and no handover is performed. If the number of candidate cells is greater than 0, step 103 is performed.

Step 103: Select a candidate cell, and determine whether the candidate cell is a co-frequency neighboring cell. If the candidate cell is not the same-frequency neighboring cell, it is consistent with the original handover decision algorithm. The cell can be used as the handover target cell by filtering, and then step 106 is performed. If the candidate cell is the same-frequency neighboring cell, step 104 is performed.

Step 104: Determine whether there is a related cell in the same frequency neighboring cell.

Querying, in the neighboring area measurement report, whether the relevant cell of the same-frequency candidate cell exists, if not, determining that the candidate cell is a mobile phone false alarm, filtering out the candidate cell, and then performing step 106; if the same frequency exists Steps 105 are performed on the relevant cells of the candidate cell.

Step 105: Determine whether there is a related cell of another intra-frequency neighboring cell that is in the same frequency as the candidate cell. In the neighboring area measurement report, it is searched whether there is another related cell of the same-frequency neighboring cell. If not, the cell can be used as the handover target cell by filtering, and then step 106 is performed; if yes, the same-frequency neighboring zone is lowered. As the priority of the handover target cell, the non-co-frequency cell is preferentially selected as the handover target cell, and then step 106 is performed.

Step 106: Determine whether there is still a candidate cell that does not perform a decision. If yes, go to step 103; if it does not exist, go to step 107;

Step 107: Perform priority processing on all the obtained target cells, select a decision to complete the handover candidate cell, and then perform a priority order determination process of the handover target cell.

Through the above policy operation, the appropriate neighboring cell can be effectively selected as the handover target cell, and the anti-co-channel interference capability of the handover algorithm is enhanced, and the inter-frequency interference caused by the same frequency is reduced in the handover process. Switch the number of dropped calls and reduce the call drop ratio.

One of ordinary skill in the art will appreciate that all or a portion of the above steps may be accomplished by a program instructing the associated hardware, such as a read-only memory, a magnetic disk, or an optical disk. Alternatively, all or part of the steps of the above embodiments may also be implemented using one or more integrated circuits. Correspondingly, each module/unit in the above embodiment may be implemented in the form of hardware or in the form of a software function module. The invention is not limited to any specific form of combination of hardware and software.

The above is only a preferred embodiment of the present invention, and of course, the present invention may be embodied in various other embodiments without departing from the spirit and scope of the invention. Corresponding changes and modifications are intended to be included within the scope of the appended claims.

Industrial Applicability In summary, a method for selecting a handover target cell and a base station controller according to an embodiment of the present invention can effectively reduce whether a neighboring cell is an intra-frequency neighboring cell identifier and a related cell in a co-frequency neighboring cell. The possibility of switching to the same-frequency neighboring cell can effectively reduce the number of dropped calls of the downlink quality difference due to the interference of the same-frequency neighboring cell, and reduce the ratio of the dropped call of the user terminal.

Claims

Claim

1. A method for selecting a handover target cell, comprising:

2. The method according to claim 1, wherein the step of the base station controller selecting the handover target cell according to the situation of the same-frequency neighboring cell and the preset related cell includes:

The method of claim 1, wherein the step of selecting, by the base station controller, the handover target cell according to the situation of the same-frequency neighboring cell and the preset related cell includes:

4. The method according to any one of claims 1-3, wherein

After the step of detecting that the same-frequency neighboring cell exists, the base station controller further includes: the base station controller configuring an identifier for the same-frequency neighboring cell;

5. A base station controller, comprising:

The configuration module is configured to: when the neighboring area data configuration is switched, if the same frequency neighboring area is detected, one or more related cells are set for the same frequency neighboring area, where the related cell is different from the serving cell Frequency neighboring area;

The obtaining module is configured to: perform a handover decision according to the neighboring area measurement report reported by the user terminal, Obtaining a handover candidate cell;

6. The base station controller according to claim 5, wherein

7. The base station controller according to claim 5, wherein

The base station controller according to any one of claims 5 to 7, wherein