CN1219380C - Method for automatic maintenance neighborlist in CDMA system - Google Patents

Abstract

The present invention provides a method of automatic neighboring area list maintenance in a CDMA system. In a CDMA cellular mobile communication system, switching is an important method for the normal talking of users between subareas, but the prerequisite of switching is that correct subarea neighboring area listing information is configured at the network side; in the practical situation, the subarea neighboring area list obtained by the base station distributed information and a practical road test in the process of network plan is not correct. The method provided by the present invention causes the subarea information not listed in the subarea neighboring areas list reported by the mobile station to obtain lost matched neighboring areas in the process of obtaining the network plan by the sieving and the matching of the not listed areas, and the lost matched neighboring areas are added to the subarea neighboring area list.

Description

A Method for Automatically Maintaining Neighbor Cell List in CDMA System

                      

The invention relates to a CDMA cellular mobile communication system, in particular to a method for automatically maintaining neighbor cell list information during handover measurement in the CDMA system.

Background technique

In the existing CDMA (Code Division Multiple Access) cellular mobile communication system, the radio frequency power of the base station is limited within a certain range (cell). When a mobile station leaves a cell and enters another cell, the signal received by the mobile station from the original cell must become weaker and weaker, while the signal it receives from the cell entering the cell will become stronger and stronger. In order to maintain the communication quality of the mobile station, it is necessary to switch the connection of the mobile station from the original base station to the newly entered base station with stronger signal. This is the concept of handover in the cellular mobile communication system.

Handover strategies in CDMA cellular mobile communication systems include network-controlled handover, mobile-assisted handover, and mobile-controlled handover. The initial cellular mobile communication systems generally use network-controlled handover strategies. And newer systems, such as GSM, IS-95 systems, etc., all adopt the strategy of mobile station assisted handover. In the 3G-WCDMA system, the mobile station assisted handover strategy is also adopted.

In the mobile station assisted handover strategy, the mobile station and the base station measure the quality of the forward and reverse channels (such as RSSI, SIR or BER, etc.) respectively, and report the measurement results to the network, and the network performs handover according to the measurement results judgment. Therefore, in the mobile station assisted handover strategy, the mobile station needs to continuously measure the quality of the forward channel of the cell it is currently in and the adjacent cell. The neighboring cells to be measured by the mobile station are specified by the measurement control issued by the network side, and the neighbor cell list information in the measurement control is specified during network optimization.

Two methods are used in combination to configure the cell neighbor list for network optimization, as shown in Figure 1. Firstly, the neighbors of the cell are determined according to the geographical distribution information of the base station, and at the same time, the drive test method is used to verify whether the configuration is reasonable. In Figure 1, there are 5 cells. If the current cell where the mobile station is located is cell 5, according to the geographical distribution of the base stations, cell 1 and cell 3 are listed as the current cell 5 when the network optimizes the configuration of the cell neighbor list. cell 4 is not listed as the neighbor cell of the current cell 5. During the drive test, when the drive test device 6 moves to the cell 5 and finds that there is no information of the neighbor cell 3 in the adjacent cell information of the cell 5, but the signal of the cell 3 can be received through the dedicated measurement equipment and special software, it means The original configuration is wrong and needs to be adjusted. However, this method requires special measurement equipment and analysis software, and the workload of measuring all the cells is quite large, and it is still not guaranteed to be comprehensive. In the actual network, there are often situations such as missing adjacent cells and cross-region coverage, resulting in the island effect. It is easy to fail when the mobile station initiates handover in this cell.

Contents of Invention

The purpose of the present invention is to propose a method for automatically maintaining a neighbor list in a CDMA system, so that after the CDMA system is put into operation, the information of the neighbor list can still be dynamically maintained, and the missing sub-district is added to the neighbor list, so that Make up for the lack of network optimization. It can not only reduce the workload of network optimization personnel, but also improve the accuracy of neighbor cell list information.

A method for automatically maintaining a neighbor list in a CDMA system, the method is implemented in the following way:

The network side sends a measurement control message to the mobile station, the measurement control message includes cell list information, and the cell list information is used to instruct the mobile station which cells to measure. The cell list consists of the cell where the mobile station is located and its neighbors. The neighbors list is configured during network planning. It is likely that some neighbors are not in the neighbors list due to missing configuration.

After receiving the measurement control message delivered by the network side, the mobile station reports the measurement reports of the cells set in the neighbor cell list to the network side. If there is no cell in the cell neighbor list, the mobile station will not report its measurement information. Therefore, corresponding conditions need to be set in the measurement control signaling to allow cells not listed in the cell list to trigger certain events. When the corresponding event is triggered, the mobile station will report the measurement results and related information of the unlisted cells. .

Within a certain period of time, after the network side counts and sorts the measurement reports, the cells that appear in the measurement reports but are not listed in the neighbor cell list are regarded as suspicious cells, that is, it is suspected that these cells were missed during network planning neighboring districts. However, during network planning, some cells are indeed intentionally not added to the list of neighboring cells of the current cell. In view of this situation, a correspondence table needs to be stored on the network side, in which each cell corresponds to some intentionally unplanned neighboring cells of the cell. In this way, the suspicious cells are matched in the correspondence table, and if they are indeed intentionally unplanned neighboring cells, these suspicious cells are filtered out, and further verification is performed on the remaining suspicious cells.

In the measurement report, the information of suspicious cells includes their local identification information, but does not include the cell global identification information. In the WCDMA system, the primary scrambling code is used as the local identification information of the cell, and the cell ID is used as the global identification information of the cell. Since the local identification information is used to locally distinguish cells, the cell global identifier information is the information that uniquely identifies the identity of the cell in the entire network. Therefore, the network side will match multiple cell global identifiers according to the local identifier of a suspicious cell. , that is, multiple suspicious cells are matched.

After the network side obtains these suspicious cells, it will judge whether these cells are in the neighboring cells of the current cell through the geographic location information. Using geographic location information as a judgment basis requires storing the latitude and longitude coordinates of the cell center and cell radius information on the network side. Wherein, the cell radius information is configured by network planners during network planning.

The network side calculates the center distance between the current cell where the mobile station is located and the suspicious cell and multiplies the compensation coefficient, and then compares it with the sum of the radii of the current cell where the mobile station is located and the suspicious cell, if the formula is satisfied:

αC _k C _j <(R _k +R _j )

Then the suspicious cell is geographically located in a neighboring cell of the current cell, and if the above formula is not satisfied, the suspicious cell is not geographically located in a neighboring cell of the current cell;

Among them, α is the compensation coefficient, and α is greater than 1;

C _k C _j is the center distance between the current cell k and the suspicious cell j;

R _k is the radius of the current cell k;

R _j is the radius of suspicious cell j.

Suspicious cells that do not satisfy the formula will not be processed, and the network side continues to judge whether the suspicious cell that satisfies the formula is in the center of the control area of the base station controller. If so, the network side automatically adds the suspicious cell to the current cell where the mobile station is located If not, the suspicious cell may be a subordinate cell of another base station controller, which is an interfering cell for the current cell, and network optimization personnel need to further confirm the suspicious cell. The cell is added to the neighbor list of the current cell where the mobile station is located.

The notable effect of the invention is that the cellular mobile communication system of the invention can greatly reduce the workload of network optimization personnel and reduce the maintenance cost of the adjacent cell list. After the CDMA system is put into operation, ordinary users are used instead of planners, and ordinary mobile stations are used instead of special measurement equipment to automatically maintain neighbor cell list information and add missing cells to the neighbor cell list to make up for the lack of network optimization. Improve the accuracy of neighbor list information. In this way, the success rate of handover is effectively guaranteed, and the system performance is improved.

Description of drawings

Figure 1: Drive test method to configure the neighborhood list of the cell

Figure 2: Geographical location map of suspicious cells in the embodiment

Figure 3: The current cell 1 in the embodiment is located at the center of the base station controller

Figure 4: The current cell 1 in the embodiment is located at the edge of the base station controller

Figure 5: Flowchart of maintenance of cell neighbor list in the embodiment

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

FIG. 5 is a flow chart of maintaining the cell neighbor list in this embodiment. After receiving the measurement control message sent by the network side, the mobile station reports the measurement report of the set reporting cell to the network side. The measurement control message includes cell list information, and the cell list information is used to indicate which cells the mobile station will measure. Wherein, the cell list is composed of the cell where the mobile station is located and its neighboring cells. The neighboring cell list is configured during network planning, and there may be missing neighboring cells. The corresponding conditions set in the measurement control signaling issued by the network side cause certain events to be triggered by cells not listed in the cell neighbor list. After the corresponding event is triggered, the mobile station will report that the cell is not listed in the neighbor list Cell measurement results and related information. For example, in the WCDMA system, the reporting standards of events 1A and 1E are set in the intra-frequency measurement control signaling, and the reporting cell of the mobile station is set as an active set cell and an unlisted set cell. The active set is the set of cells that the mobile station is communicating with. The monitoring set is a collection of cells that may enter the active set of the mobile station. They are composed of the same frequency monitoring set, different frequency monitoring set, different system monitoring set or their combination. The unlisted set is the set of neighboring cells not involved in the active set and the monitored set. When the mobile station finds that an unlisted cell satisfies the triggering conditions of 1A or 1E events through measurement, it will send a measurement report to the network side, which includes the measured value of the cell, the synchronization information of the cell, and the cell’s Main scrambling code and other related information.

Within a certain period of time, after counting and sorting the measurement reports, the network side will determine the cells that appear in the measurement reports but are not listed in the neighbor list of the current cell 1 as suspicious cells, that is, suspect that these cells are network Neighboring communities that were omitted from planning. However, during network planning, some cells are indeed intentionally not added to the list of neighboring cells of the current cell. Therefore, a correspondence table is stored on the network side, in which each cell corresponds to some intentionally unplanned neighboring cells of the cell. Match the suspicious cells one by one with the unplanned cells of the current cell 1 in the correspondence table, and filter out these suspicious cells one by one if they are intentionally unplanned neighboring cells. After filtering out suspicious cells that are intentionally unplanned, judge whether all suspicious cells have been filtered out. If there are remaining suspicious cells, then further verify the remaining suspicious cells; if they are all filtered out, then Returning to the initial step, the network side receives the measurement report reported by the mobile station again.

The remaining suspicious cell information in the measurement report includes their local identification information, but does not include cell global identification information. In the WCDMA system, the primary scrambling code is used as the local identification information of the cell, and the cell ID is used as the global identification information of the cell. Since the local identification information is used to locally distinguish cells, the cell global identifier information is the information that uniquely identifies the identity of the cell in the entire network. Therefore, the network side will match multiple cell global identifiers according to the local identifier of the suspicious cell. In this embodiment, the matched suspicious cells are cell 2 and cell 3 .

As shown in FIG. 2 , after the network side obtains the determined suspicious cells 2 and 3 , it will judge whether the cell 2 and the cell 3 are in the neighboring cells of the current cell 1 through the geographic location information. Through the geographical location information stored on the network side, determine the latitude and longitude coordinates of the center of the current cell 1, cell 2, and 3, and determine the radius of the cell as R ₁ , R ₂ , R ₃ , and the straight-line distance between cell 1 and cell 2 is calculated as C ₁ C ₂ , the linear distance between cell 1 and cell 3 and C ₁ C ₃ .

The network side calculates the center distance between the current cell where the mobile station is located and the suspicious cell and multiplies the compensation coefficient, and then compares it with the sum of the radii of the current cell where the mobile station is located and the suspicious cell, if the formula is satisfied:

αC _k C _j <(R _k +R _j )

Then the suspicious cell is geographically located in a neighboring cell of the current cell, and if the above formula is not satisfied, the suspicious cell is not geographically located in a neighboring cell of the current cell;

Among them, α is the compensation coefficient, α is greater than 1, and generally takes a value less than or equal to 2.5;

C _k C _j is the center distance between the current cell k and the suspicious cell j;

R _k is the radius of the current cell k;

R _j is the radius of suspicious cell j.

After judgment, the distance between cell 1 and cell 3 is greater than the sum of the cell radii of cell 1 and cell 3: αC ₁ C ₃ >(R ₁ +R ₃ ), while the distance between cell 1 and cell 2 is smaller than cell The sum of the cell radii of 1 and cell 2: αC ₁ C ₂ <(R ₁ +R ₂ ). It can be seen that cell 3 cannot be a neighbor of cell 1, but cell 2 is an unplanned neighbor of cell 1.

The network side continues to judge whether the suspicious cell satisfying the formula is in the center of the control area of the base station controller. If so, as shown in FIG. Suspicious cell 2 is added to the neighbor list of the current cell 1 where the mobile station is located; if not, as shown in Figure 4, the current cell 1 is at the edge of the control area 41 of the base station controller, then the suspicious cell 2 may be another A subordinate cell of the control area 42 of a base station controller is an interfering cell for the current cell 1. If the suspicious cell 2 is not added to the neighbor cell list of the current cell 1 where the mobile station is located, the suspicious cell 2 needs to be checked by network optimization personnel. Cell 2 conducts further confirmation.

Claims (7)

1, the method for automatic maintenance neighborlist in a kind of cdma system is characterized in that, said method comprising the steps of:

The measurement report that step a, network side report by travelling carriage obtains suspicious cell information, and wherein, suspicious sub-district is meant and will occurs in measurement report, and the sub-district that obtains after screen unlisted sub-district in the Neighboring Cell List;

Step b, judge by the sub-district geographical location information of network side whether described suspicious sub-district is in the position, adjacent area of the residing current area of travelling carriage, if not, step c then entered; If then enter steps d;

Step c, described suspicious sub-district are not processed, enter step g;

Steps d, judge whether current area is in the center of the control area of base station controller, if not, step e entered; If then enter step f;

Step e, suspicious sub-district is not added in the Neighboring Cell List of the residing current area of travelling carriage, manually suspicious sub-district is judged, enter step g by network planning personnel;

Step f, described network side add described suspicious sub-district in the Neighboring Cell List of the residing current area of travelling carriage to automatically;

Step g, return step a.

2, the method for automatic maintenance neighborlist in the cdma system as claimed in claim 1, it is further characterized in that network side described in the step a obtains described suspicious cell information and may further comprise the steps:

The measurement report that step 1, described network side receiving mobile report;

After step 2, described network side are added up, are sorted measurement result, with occur in the described measurement report and in Neighboring Cell List unlisted sub-district be decided to be suspicious sub-district

Step 3, described network side mate described suspicious sub-district according to mapping table, and the suspicious cell filtering that mates is fallen, and remaining suspicious sub-district is further mated;

Step 4, according to the local identities information of described remaining suspicious sub-district, mate corresponding sub-district overall identification information, the suspicious sub-district that obtains determining.

3, the method for automatic maintenance neighborlist in the cdma system as claimed in claim 2, it is further characterized in that, occur in the measurement report described in the step 2 and the sub-district of joining or not disposing intentionally for each cell configuration adjacent area hourglass when unlisted sub-district is the network optimization in the described Neighboring Cell List.

4, the method for automatic maintenance neighborlist in the cdma system as claimed in claim 2, it is further characterized in that, make the method that writes down cell information unlisted in the Neighboring Cell List in the described measurement report be in the step 2: by in the measurement control signaling of sending at network side corresponding condition being set, described corresponding conditions requires travelling carriage to allow unlisted sub-district to trigger the event report of regulation, after described event report is triggered, will write down the measurement result and the relevant information of unlisted sub-district in the measurement report that travelling carriage reports.

5, the method for automatic maintenance neighborlist in the cdma system as claimed in claim 2, it is further characterized in that the mapping table in the step 3 leaves network side in, comprising each sub-district and intentionally do not plan adjacent area corresponding with it.

6, the method for automatic maintenance neighborlist in the cdma system as claimed in claim 1, it is further characterized in that, among the step b, judges that the method whether suspicious sub-district is in the position, adjacent area of current area is:

Described network side storing has the latitude and longitude coordinates of each center of housing estate and the radius of each sub-district, described network side calculates the centre distance of residing current area of described travelling carriage and described suspicious sub-district and is multiplied by penalty coefficient, compare with the radius sum of residing current area of travelling carriage and suspicious sub-district again, if satisfy formula:

α C _kC _j＜(R _k+ R _j) then described suspicious sub-district is in the position, adjacent area of current area geographically, if do not satisfy above-mentioned formula, then described suspicious sub-district is not in the position, adjacent area of current area geographically;

Wherein, α is a penalty coefficient, and α is greater than 1;

C _kC _jCentre distance for current area k and suspicious sub-district j;

R _kIt is the radius of current area k;

R _jIt is the radius of suspicious sub-district j.

7, the method for maintenance neighborlist in the cdma system as claimed in claim 6, it is further characterized in that penalty coefficient α is greater than 1.0, smaller or equal to 2.5.

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