WO2012086108A1 - 隣接リスト最適化装置、隣接リスト生成装置、基地局装置、隣接リストの最適化方法、及び非一時的なコンピュータ可読媒体 - Google Patents
隣接リスト最適化装置、隣接リスト生成装置、基地局装置、隣接リストの最適化方法、及び非一時的なコンピュータ可読媒体 Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W60/00—Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
- H04W24/02—Arrangements for optimising operational condition
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
- H04W36/00835—Determination of neighbour cell lists
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0055—Transmission or use of information for re-establishing the radio link
- H04W36/0061—Transmission or use of information for re-establishing the radio link of neighbour cell information
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- H—ELECTRICITY
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- H04W72/51—Allocation or scheduling criteria for wireless resources based on terminal or device properties
Definitions
- the present invention relates to autonomous optimization of a neighbor list wirelessly transmitted from a base station.
- the neighbor list (also called the neighbor cell list) is used to control the handover of the mobile terminal in communication.
- the neighbor list may include handover parameters such as CIO (Cell Individual Offset).
- CIO Cell Individual Offset
- the base station transmits the adjacency list by radio to notify the adjacency list to the mobile station connected to the cell managed by itself.
- Listed Cell cells registered in the adjacent list
- Detected Cell cells not registered in the adjacent list
- a handover control entity of a serving cell such as a serving base station or a radio resource controller (RNC) generates a predetermined event. Instruct the mobile terminal to send a measurement report.
- the predetermined event is, for example, the deterioration of the radio quality of the serving cell.
- the measurement report generated by the mobile terminal includes the measurement results of the radio quality of the serving cell and its neighboring cells (adjacent cells).
- the handover control entity of the serving cell upon receiving the measurement report from the mobile terminal, determines the cell (target cell) of the handover destination based on the measurement report, and starts a handover procedure including signaling with the mobile terminal and the target cell. .
- one of the transmission events of the measurement report defined in 3GPP technical specification for Long Term Evolution (LTE) / E-UTRAN (Evolved UTRAN) is defined in 3GPP TS 36.331 V8.11.0 (2010-09).
- the essential part of the transmission event defined in the relevant technical specification as Event A3 (Neighbour becomes offset better than serving) is represented by the following equation (1).
- P S + O S ⁇ P T + O T (1) is a wireless quality measurement result of the serving cell
- P T is the measurement result of the radio quality of the neighboring cell.
- the received power of the downlink reference signals a (RSRP Reference Signal Received Power) or RSRQ (Reference Signal Received Quality).
- RSRQ is the ratio of RSRP to total received power.
- O S in Equation (1) is an offset value for the radio quality of the serving cell, and affects the radio quality of the downlink reference signal of the serving cell.
- O T is the offset value for the radio quality of the neighboring cells, acting on the radio quality of the downlink reference signals of neighboring cells. That is, the neighbor list can hold a different offset O T set for each registration cell. Offset value O T is referred to as CIO (Cell Individual Offset).
- the operating condition of equation (1) When the operating condition of equation (1) is set in the base station, the operating condition of equation (1) is notified to the mobile terminal connected to the cell managed by the base station.
- the mobile terminal transmits a measurement report to the serving base station, triggered by the measurement result of the radio quality of the serving cell and the radio quality of the adjacent cell satisfying the condition of equation (1).
- equation (1) can be rewritten as equations (2) and (3) below.
- the parameter TH HO is called the handover threshold.
- TH HO O S -O T (3)
- TTT is a protection time from when the transmission condition of the measurement report as in the above-mentioned formulas (1) and (2) is satisfied to when the transmission of the measurement report is performed.
- the mobile terminal transmits the measurement report when the period satisfying the condition of equation (2) continues beyond the period defined as TTT. That is, the longer the TTT, the later the start timing of the handover becomes, which makes it difficult for the handover to occur.
- Patent Document 1 discloses reducing handover failure (Too Late Handover, Too Early Handover) by dynamically adjusting handover parameters (TTT, CIO, etc.) based on measurement reports of mobile terminals. ing.
- TTT handover failure
- CIO handover parameters
- the base station adjusts the CIO of the adjacent cell included in the adjacent list to promote handover of the mobile terminal from the cell with large load to the adjacent cell. Disclose that.
- load distribution can be performed between cells.
- the handover control entity that has received the measurement report from the mobile terminal generally determines a target cell from among Listed Cells among adjacent cells included in the measurement report. In this case, the mobile terminal can not handover to the Detected Cell. Therefore, if there is a registration failure of the adjacent cell in the adjacent list, there is a possibility that a handover failure may occur or the communication quality may be deteriorated due to the handover to an inappropriate cell.
- the offset value Ot for each adjacent cell is notified to the mobile terminal using the adjacent list. That is, cells that can notify the mobile terminal of the offset value Ot are limited to the adjacent cells registered in the adjacent list. For this reason, if the important neighbor cell is not registered in the neighbor list, it is not possible to notify the mobile terminal of the offset value Ot related to the important neighbor cell.
- improvement of the handover success rate based on the adjustment of the offset value Ot (for example, patent document 1) It becomes difficult to realize load distribution (for example, non-patent document 1) and the like by handover. This problem also occurs when the handover control entity of the serving cell can select the target cell from the Detected Cells.
- the offset value for each adjacent cell as described above can also be set for the radio quality measured by the mobile terminal at the start of communication, independently of CIO.
- cells that can notify the mobile terminal of the offset value (qoffset) are limited to the adjacent cells registered in the adjacency list, and thus load balancing is performed if important adjacent cells are not registered in the adjacency list. It will be difficult to realize.
- optimization of the neighbor list is important to ensure good communication quality.
- it since there is an upper limit to the number of cells that can be registered in the adjacency list, it is necessary to preferentially register in the adjacency list important cells that are likely to contribute to improvement in communication quality.
- Non-Patent Document 2 discloses that the neighboring list registration is preferentially performed on neighboring cells where there are many measurement reports from the mobile terminal and neighboring cells where there are many handover attempts of the mobile terminal.
- the HetNet environment is an environment in which multiple types of cells having different coverage sizes (cell sizes), such as macro cells and pico cells, macro cells and femto cells, and pico cells and femto cells, are arranged adjacent to each other. Note that the adjacent arrangement of cells in the HetNet environment includes a hierarchical arrangement in which coverage of one of the large cell sizes completely includes the other small cell size.
- Non-Patent Document 2 uses a common reference (specifically, the number of measurement reports and the number of handover attempts) for a plurality of adjacent cells to list cells (adjacency list) from among the plurality of adjacent cells. It is only disclosed to perform the selection of registered cells of However, in a HetNet environment including, for example, macro cells and pico cells, pico cells are less likely to be registered in the adjacency list because the number of measurement reports on macro cells and the number of handover attempts are generally larger than those of pico cells. Therefore, there is a possibility that the adjacent list can not be optimized only by selecting the listed cells according to the common criteria.
- Non-Patent Document 1 it is preferable to register adjacent cells (mainly picocells) installed for load distribution in the adjacent list.
- the method of Non-Patent Document 2 for selecting a cell to be registered in the adjacency list uses a common reference regardless of whether it is a macro cell or a pico cell, and it is an adjacent cell that can be easily selected as a handover destination, ie, wireless Adjacent cells with high quality are preferentially registered in the adjacency list. For this reason, there may be a case where adjacent cells with high radio quality (mainly macro cells) are registered in the adjacent list, and adjacent cells (mainly pico cells) for load distribution are not registered in the adjacent list.
- adjacent cells with high radio quality mainly macro cells
- adjacent cells mainly pico cells
- the present invention has been made based on the above-mentioned findings by the inventors of the present application, and is an adjacency list optimization device capable of optimizing adjacency list suitable for HetNet (Heterogeneous Network) environment, adjacency list optimization device It is an object of the present invention to provide a list generation device, a base station device, an adjacent list optimization method, and a program.
- HetNet Heterogeneous Network
- a first aspect of the present invention includes an adjacency list optimization device that optimizes adjacency list wirelessly transmitted by a base station that manages a target cell.
- the adjacent list optimization apparatus takes account of the cell type determined according to the difference in cell size, and among the plurality of other cells excluding the target cell, the plurality of registered cells registered in the adjacent list. It has a cell selection unit to select.
- a second aspect of the invention involves an adjacency list generator.
- the adjacency list generator is combined with the adjacency list optimizer according to the first aspect of the present invention described above, and generates an adjacency list including information on the plurality of registered cells selected by the adjacency list optimizer. It is configured to
- a third aspect of the present invention includes a base station apparatus.
- the base station apparatus is combined with the adjacent list generation apparatus according to the second aspect of the present invention described above, and configured to wirelessly transmit an adjacent list including information on the plurality of registered cells.
- a fourth aspect of the present invention includes a neighbor list optimization method for optimizing a neighbor list wirelessly transmitted by a base station that manages a target cell.
- the method includes the step of selecting a plurality of registered cells registered in the adjacent list from among a plurality of other cells excluding the target cell in consideration of a cell type determined according to a difference in cell size. Have.
- a fifth aspect of the invention comprises a computer program.
- the program causes the computer to perform the neighbor list optimization method according to the fourth aspect of the present invention described above by being read and executed by the computer.
- the adjacency list suitable for the HetNet (Heterogeneous Network) environment in which cells of a plurality of types with different coverage sizes (cell sizes) are arranged adjacent to each other.
- An adjacent list optimization device, an adjacent list generation device, a base station apparatus, an adjacent list optimization method, and a program can be provided.
- FIG. 1 shows the structural example of the network containing the hand-over optimization system which concerns on Embodiment 1 of this invention. It is a flowchart which shows the example of the whole procedure of the adjacent list update process performed by the hand-over optimization system shown in FIG. It is a flowchart which shows the 1st example of the selection procedure of the registration cell to the adjacent list which concerns on Embodiment 1 of this invention. It is a flowchart which shows the 2nd example of the selection procedure of the registration cell to the adjacent list which concerns on Embodiment 1 of this invention. It is a flowchart which shows the 3rd example of the selection procedure of the registration cell to the adjacent list which concerns on Embodiment 1 of this invention.
- FIG. 1 is a diagram showing an example of the configuration of a network including the handover optimization system 1 according to the present embodiment.
- the handover optimization system 1 performs an update process on the neighbor list related to the target cell 61.
- the neighbor list of the target cell 61 is transmitted from the base station 2 that manages the target cell 61 using a radio channel that can be received by the mobile terminal (hereinafter, UE: User Equipment) 3.
- UE User Equipment
- the handover optimization system 1 includes an adjacent list optimization unit 11 and an adjacent list generation unit 12.
- the adjacent list optimization unit 11 selects a plurality of registered cells from among the plurality of adjacent cells 62 adjacent to the target cell 61 in consideration of the cell type determined according to the difference in cell size. The selection process of the registered cell is performed by the cell selection unit 110.
- the adjacent list optimization unit 11 optimizes the adjacent list related to the target cell 61 by selecting such a registered cell.
- the adjacent list generation unit 12 generates an adjacent list in which information on a plurality of registered cells selected by the adjacent list optimization unit 11 is described, and supplies the generated adjacent list to the base station 2.
- the target cell 61 is a macro cell, and only two adjacent cells 62 including one macro cell and one pico cell are shown. However, the target cell 61 may be another cell other than the macro cell. Also, the target cell 61 may have more neighboring cells.
- the selection process of registered cells by the adjacent list optimization unit 11 is particularly effective when the total number of adjacent cells 62 is larger than the maximum registrable number NCLmax (for example, 32 in LTE) of the adjacent list.
- the cell selection unit 110 uses neighboring cell information (cell ID and the like) on a plurality of neighboring cells 62 to select a registered cell. Neighboring cell information can be supplied to the neighbor list optimization unit 11 through various routes. For example, the neighboring cell information can be acquired by referring to the measurement report (MR: Measurement Report) generated by the UE 3 or the MR aggregation information in which the plurality of measurement reports are aggregated by the base station 2 or the like. Since the measurement report includes the measurement result of the radio quality of the adjacent cell 62 detected by the UE 3, the adjacent cell 62 can be identified.
- MR Measurement Report
- the different element management system Element Management System
- NMS network management system
- the neighboring cell information may be acquired from the network design information held by the base station 2 or the EMS or NMS that manages this.
- the network design information includes cell layout information created by an operator or the like of a telecommunications carrier.
- the cell selection unit 110 selects a registered cell in consideration of the cell type determined according to the difference in cell size. Therefore, the cell selection unit 110 uses cell type information on the adjacent cell 62 in order to select a registered cell.
- the cell type information may be capable of identifying the difference in cell size of the adjacent cell 62.
- the cell type information may be information directly indicating the cell size.
- the cell type information may be an identifier indicating to which of the attributes divided according to the cell size of the macro cell, the micro cell, the pico cell, the femto cell, etc. the adjacent cell belongs.
- the cell type information may be information indicating the transmission power level of the radio signal (eg, pilot signal, downlink reference signal) by the base station that manages each adjacent cell 62.
- the cell type information is information that indicates the application of the cell, for example, information that can identify whether the cell is a normal cell or a smaller cell than a normal cell installed for load distribution. It is also good.
- Cell type information can be supplied to the adjacent list optimization unit 11 through various routes.
- the adjacent list optimization unit 11 may obtain the cell type information also from the measurement report (or the MR aggregated information) of the UE 3 or the network design information, or a combination thereof, similarly to the above-described adjacent cell information.
- the cell type information may be included in the transmission signal of each base station that manages the adjacent cell 62.
- cell type information may be acquired from a base station that manages an adjacent cell included in measurement information of UE3.
- the cell selection unit 110 uses a cell selection index (CSI: Cell Selection Index) to select a plurality of registered cells from among the plurality of adjacent cells 62.
- CSI Cell Selection Index
- Typical examples of the cell selection indicator are "the number of detections by UE3 (the number of measurement reports)” and “the number of handover (HO) trials” as described in Non-Patent Document 2.
- the “HO trial number” refers to the number of outbound handover trials from the target cell 61 to the adjacent cell 62.
- the cell selection indicator may include "HO failure number”, “HO failure rate”, or "failure number occupancy rate”.
- the “HO failure number” refers to the number of outbound handover failures from the target cell 61 to the adjacent cell 62.
- HO failure rate means the ratio of the number of failures to the number of outbound handover attempts from the target cell 61 to the adjacent cell 62.
- the “occupancy rate of the number of failures” means the ratio of the number of failures of outbound handover from the target cell 61 to the adjacent cell 62 with respect to the total number of failures of outbound handover from the target cell 61.
- the cell selection unit 110 may preferentially select an adjacent cell 62 having a large occupancy rate of the HO failure number, the HO failure rate, or the failure number as a registered cell. As a result, it becomes possible to adjust handover parameters such as CIO for these cells, and it is possible to suppress the occurrence of handover to a neighboring cell where handover failure is expected. That is, handover failure can be reduced.
- the cell selection unit 110 changes the reference for selecting a registered cell according to the cell type. For example, for the adjacent macro cell, a first criterion is selected to preferentially select a cell having a large first index (at least one of the number of detections by UE3 and the number of HO attempts) as a registered cell.
- the second index eg HO number of failure, HO failure rate, or occupancy ratio of failure number
- Adopt the criteria of The first and second indices may each include a plurality of indices.
- the combination of indices for macro cells may be different from the combination of indices for adjacent cells of other types.
- the cell selection unit 110 uses the same index regardless of the cell type, when selecting a registered cell, the threshold to be compared with the index may be changed according to the cell type. For example, when using "the number of detections by UE3" as a common index, a high threshold is applied for the adjacent macro cell, and a lower threshold is adopted for other adjacent cells (for example, adjacent pico cells) compared to the macro cell. Good.
- Non-Patent Document 2 In the method of using a common reference without considering the cell type as described in Non-Patent Document 2, there is a possibility that only a specific type of cell is selected as a registered cell, and almost no other type of cell is selected. is there. However, such a defect can be avoided by changing the criteria for selecting a registered cell according to the cell type.
- FIGS. 2A-2C are tables showing specific examples of cell selection indicators.
- FIG. 2A shows the result of counting the number of measurement reports from UE 3 for each adjacent cell.
- the aggregation result of the number of measurement reports is prepared by the base station 2, the handover control entity of the adjacent cell 62 (RNC (Radio Network Controller), etc.), or the EMS or NMS, etc. managing the base station 2, and the adjacent list optimization unit It may be supplied to 11. Also, the aggregation result of the number of measurement reports may be created by the handover optimization system 1 collecting measurement reports from the UE 3.
- RNC Radio Network Controller
- a large number of measurement reports means that the cell is a neighbor cell observed (detected) by a large number of UEs 3 connected to the target cell 61, and means a neighbor cell that is likely to cause a handover from the target cell 61. Do. In general, such adjacent cells are often cells with large coverage. Therefore, the number of measurement reports may be adopted as a selection indicator for cells with relatively large coverage. For example, when applied to a HetNet environment including macro cells and pico cells, the number of measurement reports may be adopted as a selection indicator (macro selection indicator I_M) for the macro cell.
- FIG. 2B shows statistical information on handover. Specifically, FIG. 2B shows the number of outbound HO attempts from the target cell 61 to the adjacent cell 62 (second column), the number of outbound HO failures to the adjacent cell 62 (third column), and the adjacent cell 62. The failure rate of the Outbound HO (column 4) and the occupancy rate of the number of failures of the Outbound HO to the adjacent cell 62 (column 5) are shown.
- the statistical information related to these handovers may be prepared by a control entity (eg, a base station or RNC) that controls the handover of the target cell 61 and the adjacent cells 62, or by the EMS or NMS, and supplied to the adjacent list optimization unit 11.
- a control entity eg, a base station or RNC
- the number of Outbound HO attempts to the adjacent cell 62 may be adopted as a selection index (macro selection index I_M) for the macro cell.
- a large number of outbound HO attempts means a neighboring cell that is likely to cause a handover from the target cell 61, and such a neighboring cell is generally a macro cell in many cases.
- the other three indices in FIG. 2B may be adopted as selection indices for pico cells (pico selection indices I_P). It is possible to reduce handover failures by preferentially registering neighboring pico cells with a high number of handover failures or failure rates in the neighboring list and adjusting CIOs for these neighboring pico cells to large values.
- FIG. 2C shows other monitoring information on the adjacent cell 62. Specifically, FIG. 2C shows the number of reconnection of the UE to the adjacent cell 62 (second column), and the average stay time of the UE in the adjacent cell 62 (third column). These pieces of monitoring information may be created by a base station that manages the adjacent cell 62, a node that manages the base station, or the EMS or NMS, and may be supplied to the adjacent list optimization unit 11.
- the number of reconnection of UEs to the adjacent cell 62 may be adopted as a selection indicator for macro cells (macro selection indicator I_M).
- the large number of UE reconnections means a neighboring cell that is likely to cause a handover from the target cell 61, and such a neighboring cell is generally a macro cell in many cases.
- the average residence time of the UE in the adjacent cell 62 may be adopted as a pico cell selection indicator (pico selection indicator I_P). Even if the UE 3 is handed over to the adjacent cell 62 whose average stay time is short, there is a high possibility that it will return to the target cell 61 immediately.
- the cell selection unit 110 secures a part of the maximum registrable number NCLmax of the adjacent list as a registration frame (reservation frame) for at least one cell type (for example, pico cell). In other words, the cell selection unit 110 sets the registration upper limit number (the value obtained by subtracting the number of reservation slots from the maximum registrable number NCLmax of the adjacency list) in at least one cell type (for example, macro cell).
- the cell selection unit 110 sets the registration frame for each cell type by dividing the maximum registrable number NCLmax of the adjacency list, and selects a registered cell within the range of each registration frame for each cell type. Good. According to these, even when a registered cell is selected based on a common reference regardless of the cell type, it is possible to reliably register a cell group of a plurality of cell types in the adjacent list.
- first and second examples of registered cell selection described above may be used in combination. By combining these, it is possible to adopt a selection criterion adapted to the cell type and to reliably register a cell group of a plurality of cell types in the adjacent list.
- the neighboring list optimization unit 11 registers a plurality of neighboring cells 62 in the neighboring list in consideration of the cell type determined according to the difference in cell size. Select the registration cell of. Therefore, according to the present embodiment, it is possible to optimize the adjacency list suitable for the HetNet environment.
- the arrangement of the adjacent list optimization unit 11 and the adjacent list generation unit 12 is appropriately determined based on the design concept of the network architecture.
- EPS Evolved Packet System
- a base station evolved Node B (eNB) having a handover control function by arranging the neighbor list optimization unit 11 in the NMS 4
- the neighbor list generator 12 may be arranged in 2).
- the NMS 4 supplies the cell type information included in the network design information 41 to the adjacent list optimization unit 11.
- the NMS 4 receives measurement report (MR) tally information and handover (HO) statistical information from the base station 2 and holds it as cell monitoring information 42.
- the NMS 4 supplies the adjacent cell information and the cell selection index (CSI) included in the cell monitoring information 42 to the adjacent list optimization unit 11.
- MR measurement report
- HO handover statistical information
- the neighbor list optimization unit 11 is disposed in the NMS 4 and the neighbor list generation unit 12 is provided in the RNC 5 having a handover control function. May be arranged.
- UMTS Universal Mobile Telecommunications System
- cell type information may be acquired from the measurement report of UE3.
- the configuration shown in FIG. 5 may be adopted as a modification of FIG. That is, the NMS 4 may supply the neighboring cell optimization unit 11 with the neighboring cell information, the cell type information, and the cell selection index (CSI) included in the cell monitoring information 42.
- CSI cell selection index
- FIG. 6 is a flowchart showing an overall procedure of neighbor cell list update by the handover optimization system 1.
- the adjacent list optimization unit 11 acquires adjacent cell information and its cell type information.
- the adjacent list optimization unit 11 refers to a cell selection index (CSI).
- the adjacent list optimization unit 11 selects a registered cell in consideration of the cell type. The selection of the registered cell in step S3 may be performed by any of the two examples described above or a combination of the two.
- the adjacent list generation unit 12 generates an adjacent list including information on the plurality of registered cells selected in step S3.
- FIGS. 7 to 11 describe the case where the plurality of adjacent cells 62 include macro cells and pico cells, they may be replaced with a combination of other cells having different cell sizes. Also, the procedures of FIGS. 7 to 11 may be applied to an environment where there is a large coverage neighboring cell group including macro cells and macro cells and a small coverage neighboring cell group including pico cells and femto cells, for example.
- the procedure shown in FIG. 7 corresponds to the first example described above. That is, the procedure shown in FIG. 7 is characterized in that the selection criterion of the registered cell is changed according to the cell type.
- the cell selection unit 110 initializes sets S3 and S4 as empty sets.
- the sets S3 and S4 may be defined, for example, as array variables in a computer program.
- step S12 the cell selection unit 110 selects a registered cell from among the plurality of adjacent cells 62 among the adjacent macro cell set S1 according to the selection criteria of the macro cell within the range of the maximum registrable number NCLmax of the adjacent list.
- the selection criterion of the macro cell may be, for example, a criterion for performing any one threshold comparison of the macro selection indicator I_M described above.
- the adjacent macro cell selected in step S12 is put into registered cell set S3. Further, the number of adjacent macro cells selected in step S12 is N3.
- step S13 the cell selection unit 110 selects the neighboring pico cell set S2 of the plurality of neighboring cells 62 according to the pico cell selection criteria within the range of the remaining number of cells that can be registered in the neighboring list (that is, NCLmax-N3). Select a registration cell from.
- the selection criterion of the pico cell may be, for example, a reference for performing any threshold comparison of the pico selection indicator I_P described above.
- the adjacent pico cells selected in step S13 are put into registered cell set S4. Further, the number of adjacent pico cells selected in step S13 is N4.
- step S14 the cell selection unit 110 determines the cells included in the registered cell sets S3 and S4 as registered cells. If the number of cells included in the registered cell sets S3 and S4 is smaller than the maximum registrable number NCLmax, the unselected adjacent cell 62 may be further selected as a registered cell. Also, the registration cell may be selected from the adjacent pico cell prior to the adjacent macro cell. However, in an environment where the number of adjacent picocells is larger than the maximum registrable number NCLmax, it is preferable to carry out in the order of FIG.
- the procedure shown in FIG. 8 corresponds to the second example described above. That is, the procedure shown in FIG. 8 secures a part of the maximum registrable number NCLmax of the adjacent list as a registration frame (reservation frame) for at least one cell type (for example, pico cell). In the example of FIG. 8, the number of reservation slots for pico cells is NP. Step S21 of FIG. 8 is the same as step S11 of FIG.
- step S22 the cell selection unit 110 selects a registered cell from among the adjacent macro cell set S1 within the range of the registration upper limit number of macro cells (NCLmax-NP).
- the adjacent macro cell selected in step S22 is put into registered cell set S3. Further, the number of adjacent macro cells selected in step S22 is N3.
- step S23 the cell selection unit 110 selects a registered cell from among the adjacent pico cell set S2 within the range of the number of remaining cells (NCLmax-N3) that can be registered in the adjacent list.
- the adjacent pico cells selected in step S23 are put into registered cell set S4. Further, the number of adjacent pico cells selected in step S23 is N4.
- the cell selection unit 110 determines the cells included in the registered cell sets S3 and S4 as registered cells.
- the cell selection unit 710 may further select an unselected adjacent cell 62 as a registered cell.
- the registration cell may be selected from the adjacent pico cell prior to the adjacent macro cell. In this case, the cell selection unit 110 may select a registered cell from the adjacent pico cell set S2 within the range of the number of reservation slots NP of the pico cell.
- the procedure shown in FIG. 9 corresponds to the combination of the first and second examples described above. That is, the procedure shown in FIG. 8 changes the selection criteria of the registered cell according to the cell type, and at the same time, registers a part of the maximum registrable number NCLmax of the adjacent list for at least one cell type (eg pico cell) Secure as). Also in the example of FIG. 9, the number of reservation slots for pico cells is NP. Step S31 in FIG. 9 is the same as step S11 in FIG.
- step S32 the cell selection unit 110 selects a registered cell from the adjacent macro cell set S1 in accordance with the selection criterion of the macro cell within the upper limit number of registered macro cells (NCLmax-NP).
- step S33 the cell selection unit 110 selects a registered cell from among the adjacent picocell set S2 in accordance with the picocell selection criteria within the range of the remaining number (NCLmax-N3) of cells that can be registered in the adjacent list.
- Step S34 is the same as step S24 in FIG.
- the procedure shown in FIG. 10 is a modification of the procedure of FIG.
- the adjacent macro cell is smaller than the upper limit number of registrations (NCLmax-NP), or the adjacent pico cell is smaller than the number of reservation slots (NP), or both the adjacent macro cell and the adjacent pico cell are both smaller.
- the registered cell number may not reach the maximum registrable number NCLmax of the adjacent list. Therefore, the procedure in FIG. 10 shows an example in which further cell selection is performed when the number of cells included in the registered cell sets S3 and S4 falls below the maximum registrable number NCLmax.
- step S41 in FIG. 10 the cell selection unit 110 initializes sets S3 to S6 as empty sets.
- Steps S42 and S43 of FIG. 10 are similar to steps S32 and S33 shown in FIG.
- step S44 it is determined whether the number of cells (N3 + N4) included in the registered cell sets S3 and S4 is less than the maximum registrable number NCLmax. If N3 + N4 is smaller than NCLmax (YES in step S44), the remaining adjacent macrocells (S1-S3) are selected according to the macrocell selection criteria within the range of the remaining number of cells (NCLmax-N3-N4) that can be registered in the adjacent list.
- the registration cell is selected from among (step S45). Note that the macro cell selection standard here may be changed in threshold value so that the registered cell can be selected more easily than the standard in step S42.
- the adjacent macro cell selected in step S45 is put into registered cell set S5. Further, the number of adjacent macro cells selected in step S45 is N5.
- step S46 it is determined whether the number of cells (N3 + N4 + N5) included in the registered cell sets S3 to S5 is less than the maximum registrable number NCLmax. If N3 + N4 + N5 is smaller than NCLmax (YES in step S46), the remaining adjacent picocells (S2 ⁇ ) are selected according to the picocell selection criteria within the range of the remaining number of cells (NCLmax ⁇ N3-N4-N5) that can be registered in the adjacent list. A registered cell is selected from S4) (step S47).
- the pico cell selection criterion here may change the threshold value so that the registered cell is more easily selected than the criterion at step S43.
- the adjacent pico cells selected in step S47 are put into registered cell set S6. Further, the number of adjacent picocells selected in step S47 is N6.
- step S48 the cell selection unit 110 determines the cells included in the registered cell sets S3 to S6 as registered cells.
- the procedure in FIG. 11 introduces a common indicator (referred to as an evaluation parameter) that does not depend on the cell type for selection of a registered cell.
- an evaluation parameter a common indicator that does not depend on the cell type for selection of a registered cell.
- the procedure in FIG. 11 takes into account differences in cell types by making the method of determining the evaluation parameter different between macro cells and pico cells.
- step S51 the cell selection unit 110 calculates an evaluation parameter by multiplying the first index (for example, the number of measurement reports of UE3) by the first weighting factor W1 for each cell included in the adjacent macro cell set S1. .
- step S52 the cell selection unit 110 calculates an evaluation parameter by multiplying the second index (for example, the number of HO failures) by the second weighting factor W2 for each cell included in the adjacent picocell set S2.
- the second index for example, the number of HO failures
- step S53 the cell selection unit 110 selects a registered cell from the adjacent cell set (S1 + S2) in the order of the magnitudes of the evaluation parameters within the range of the maximum registrable number NCLmax of the adjacent list.
- the cell selection indicator (CSI) described in the first embodiment of the invention is only an example. Also, a plurality of indicators may be used in combination. For example, with respect to adjacent pico cells, a selection criterion may be adopted in which cells having a large HO failure rate are selected from cells in which the number of measurement reports exceeds a threshold.
- some cells may be statically registered in the adjacency list without setting all the registrable frames of the adjacency list as targets of dynamic cell selection by the adjacency list optimization unit 11.
- dynamic cell selection by the adjacent list optimization unit 11 may be performed with the upper limit being the number obtained by subtracting the number of statically registered cells from the maximum registrable number NCLmax of the adjacent list.
- the adjacent cell 62 may be any other cell than the target cell 61.
- the other cells include cells whose coverage partially overlaps with the coverage of the target cell 62 and cells whose coverage is completely included in the coverage of the target cell 62. Also, although the overlapping relationship of coverage with the target cell 62 is not clear, the cell detected by the UE 3 connected to the target cell 62 is included in the other cells described above.
- the embodiment has been described in which the registered cell selection process in consideration of the cell type is always performed.
- the communication load of the target cell 61 is predetermined. It may be performed only when the threshold is exceeded. It is effective to select a cell for load distribution such as a pico cell as a registered cell as a registered cell when load distribution of the target cell 61 is desired.
- the communication load of the target cell 61 is large, it is possible to make it easy to select a cell whose load is to be distributed, such as a pico cell, among the adjacent cells as a registered cell.
- the registered cell selection considering the cell type is not performed, and among the adjacent cells, the macrocell having the large number of measurement reports and the number of HO trials is registered as a registered cell. It can be easily selected, and the HO quality of the macro cell can be preferentially improved.
- the selection process of the registered cell by the cell selection unit 110 described in the first embodiment of the invention may be realized using a semiconductor processing device such as an application specific integrated circuit (ASIC) or a digital signal processor (DSP). Further, the process of selecting a registered cell by the cell selection unit 110 may be realized by causing a computer such as a microprocessor to execute a program. Specifically, a program including instructions for causing a computer to execute the algorithm shown in any of FIGS. 7 to 11 may be created, and the program may be supplied to the computer.
- ASIC application specific integrated circuit
- DSP digital signal processor
- Non-transitory computer readable media include tangible storage media of various types. Examples of non-transitory computer readable media are magnetic recording media (eg flexible disk, magnetic tape, hard disk drive), magneto-optical recording media (eg magneto-optical disk), CD-ROM (Read Only Memory), CD-R, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)) are included. Also, the programs may be supplied to the computer by various types of transitory computer readable media. Examples of temporary computer readable media include electrical signals, light signals, and electromagnetic waves. The temporary computer readable medium can provide the program to the computer via a wired communication path such as electric wire and optical fiber, or a wireless communication path.
- a wired communication path such as electric wire and optical fiber, or a wireless communication path.
- the “HO failure number”, “HO failure rate”, or “occupancy rate of failure number” from the target cell 61 to the adjacent cell 62 is used as a cell selection index. Mentioned the example used. As described above, it is possible to select a registered cell using the criteria for preferentially selecting the number of outbound handover failures from the target cell 61 to the adjacent cell 62 or a cell having a relatively high failure rate as described in Non-Patent Document 2 It is a matter that is not described.
- the selection of the registered cell based on the number of failures of the outbound handover to the adjacent cell 62 or the failure rate as an indicator without taking into consideration the cell type defined in accordance with the difference in cell size is an essential element here.
- a reference example for performing will be described.
- FIG. 12 is a view showing an example of the configuration of a network including the handover optimization system 7 according to this embodiment.
- the outline of FIG. 12 is the same as that of FIG. 1 described above. That is, the handover optimization system 7 performs the update process of the adjacent list on the target cell 61.
- the neighbor list of the target cell 61 is transmitted from the base station 2 that manages the target cell 61 using a radio channel that can be received by the UE 3.
- the handover optimization system 7 includes an adjacent list optimization unit 71 and an adjacent list generation unit 12.
- the neighbor list optimization unit 71 is a criterion for preferentially selecting a cell having a relatively large number of failures or a failure rate of an outbound handover from the target cell 61 to the adjacent cell among the plurality of adjacent cells 62. Is used to select a plurality of registered cells registered in the adjacent list.
- the adjacent list generation unit 12 generates an adjacent list in which the information of the plurality of registered cells selected by the adjacent list optimization unit 71 is described, and supplies the adjacent list to the base station 2.
- FIG. 13 is a flow chart showing an overall procedure of neighbor cell list update by the handover optimization system 7.
- the adjacent list optimization unit 71 acquires adjacent cell information.
- the adjacent list optimization unit 71 refers to a cell selection index (CSI).
- the adjacent list optimization unit 71 (that is, the cell selection unit 710) gives priority to a cell having a relatively large number of failures or failure rate of outbound handover from the target cell 61 to the adjacent cell.
- the registration cell is selected using the criteria selected in.
- step S104 the adjacent list generation unit 12 generates an adjacent list including information on the plurality of registered cells selected in step S103. Subsequently, three specific examples of the registration cell selection procedure in step S103 of FIG. 13 will be described in more detail with reference to flowcharts (FIGS. 14 to 16).
- step S201 in FIG. 14 the cell selection unit 710 selects registered cells from the adjacent cell set in the order of the HO failure number or the HO failure rate within the range of the maximum registrable number NCLmax of the adjacent list.
- step S301 the cell selection unit 710 initializes sets S3 and S4 as empty sets.
- step S302 the cell selection unit 710 selects a registered cell from the neighboring cell set S1 in accordance with the criteria using the HO failure number or the HO failure rate within the upper limit number of registrations (NCLmax ⁇ NS2).
- the number NS2 represents the number of registration slots (reservation slots) reserved for cells selected using other criteria described later.
- the adjacent cells selected in step S302 are put into the registered cell set S3. Further, the number of adjacent cells selected in step S302 is N3.
- step S303 the cell selection unit 710 sets the other criteria (for example, different from the criteria using the HO failure count or the HO failure rate) within the range of the number of remaining cells (NCLmax-N3) that can be registered in the neighbor list (for example, Based on the number of measurement reports of UE 3 as the indicator), the registered cell is selected from the remaining adjacent cells (S1-S3).
- the adjacent cells selected in step S303 are put into registered cell set S4. Further, the number of adjacent cells selected in step S303 is N4.
- step S304 the cell selection unit 710 determines the cells included in the registered cell sets S3 and S4 as registered cells. When the number of cells included in the registered cell sets S3 and S4 is less than the maximum registrable number NCLmax, the cell selection unit 710 may further select an unselected adjacent cell 62 as a registered cell.
- the procedure shown in FIG. 16 is a modification of the procedure of FIG.
- the procedure of FIG. 15 shows an example in which further cell selection is performed when the number of cells included in the registered cell sets S3 and S4 is less than the maximum registrable number NCLmax.
- step S401 in FIG. 16 the cell selection unit 710 initializes sets S3 to S6 as empty sets.
- Steps S402 and S403 of FIG. 16 are similar to steps S302 and S303 shown in FIG.
- step S404 it is determined whether the number of cells (N3 + N4) included in the registered cell sets S3 and S4 is less than the maximum registrable number NCLmax. If N3 + N4 is smaller than NCLmax (YES in step S404), the remaining number of remaining cells (NCLmax-N3-N4) that can be registered in the adjacent list is determined according to the criteria using HO failure number or HO failure rate A registered cell is selected from adjacent cells (S1-S3-S4) (step S405). Note that the reference for selection of registered cells here may be changed in threshold value so that the registered cell can be selected more easily than the reference in step S402. The adjacent cells selected in step S405 are put into the registered cell set S5. Further, the number of adjacent cells selected in step S405 is N5.
- step S406 it is determined whether the number of cells (N3 + N4 + N5) included in the registered cell sets S3 to S5 is less than the maximum registrable number NCLmax.
- N3 + N4 + N5 is smaller than NCLmax (YES in step S406), within the range of the remaining number of cells that can be registered in the adjacent list (NCLmax-N3-N4-N5), the criteria using HO failure number or HO failure rate
- a registered cell is selected from the remaining adjacent cells (S1-S3-S4-S5) according to other different criteria (step S407).
- the selection criterion of the registration cell here may be changed in threshold so that the registration cell can be selected more easily than the criterion in step S403.
- the adjacent cells selected in step S407 are put into registered cell set S6. Further, the number of adjacent cells selected in step S407 is set to N6.
- step S408 the cell selection unit 710 determines the cells included in the registered cell sets S3 to S6 as registered cells.
- the selection process of the registered cell by the cell selection unit 710 described in the reference example 1 may be realized using a semiconductor processing device such as an application specific integrated circuit (ASIC) or a digital signal processor (DSP). Further, the process of selecting a registered cell by the cell selection unit 710 may be realized by causing a computer such as a microprocessor to execute a program. Specifically, a program including an instruction group for causing a computer to execute the algorithm shown in any of FIGS. 14 to 16 may be created, and the program may be supplied to the computer.
- ASIC application specific integrated circuit
- DSP digital signal processor
- Embodiment 1 of the invention Part or all of Embodiment 1 of the invention, the other embodiments, and Reference Example 1 may be described as in the following appendices, but is not limited to the following.
- a neighbor list optimization apparatus that optimizes a neighbor list wirelessly transmitted by a base station that manages a target cell, comprising: Among the plurality of other cells excluding the target cell, using a first criterion for preferentially selecting a cell having a relatively large number of failures or failure rates of outward handover from the target cell to the other cell, among the plurality of other cells excluding the target cell
- An adjacent list optimization device comprising cell selection means for selecting a plurality of registered cells registered in the adjacent list.
- the failure rate may be the ratio of the number of failures to the number of outgoing handover attempts from the target cell, or the total number of outgoing handover failures from the target cell for the outward handover to the other cell.
- APPENDIX 4 The adjacency list optimization device according to appendix 1, wherein the proportion is the number of failures.
- the cell type includes a first cell type, and a second cell type indicating a second cell having a different cell size from the first cell indicated by the first cell type,
- the cell selection means From the first cell group included in the plurality of other cells, select a registered cell according to the first criterion, From the second cell group included in the plurality of other cells, select a registered cell according to a second criterion different from the first criterion,
- the adjacency list optimization device according to any one of appendices 1 to 3.
- the cell selection means may be configured to select one of the number of the first cells and the number of the second cells included in the plurality of other cells if the number exceeds the maximum registrable number of the adjacent list.
- the adjacent list optimization device according to appendix 4, wherein the plurality of registered cells are selected such that the first and second cells are both registered in the adjacent list.
- the second cell is a cell having a cell size larger than that of the first cell, and
- the second criterion is that, among the second cell group, a cell which is predicted to cause a lot of outward handovers from the target cell to the second cell is preferentially selected as the registered cell.
- the second cell is a cell having a cell size larger than that of the first cell, and
- the second criterion is that among the second group of cells, the number of detections by the mobile terminal, the number of outgoing handover attempts from the target cell to the second cell, or the number of reconnection of the mobile terminal is relative.
- the neighbor list optimization device according to any one of appendices 4 or 5, comprising preferentially selecting a large cell as the registered cell.
- the cell selection means The registered cell is preferentially selected from the second cell group, The registered cell is selected from the first cell group within the range of the remaining number of cells that can be registered in the adjacent list. 24.
- the adjacent list optimization device according to any one of appendices 4 to 7.
- the cell selection means According to the first criterion, a registered cell is preferentially selected from the plurality of other cells, and The registered cell is selected from the group of unselected cells among the plurality of other cells according to a second criterion different from the first criterion within the range of the remaining number of cells that can be registered in the adjacent list , Adjacency list optimization apparatus according to appendix 1 or 2.
- An adjacent list generation device for generating an adjacent list including information on the plurality of registered cells.
- a base station apparatus configured to wirelessly transmit an adjacent list including information on the plurality of registered cells.
- Handover Optimization System 1 Handover Optimization System 2 Base Station 3 Mobile Terminal 4 Network Management System (NMS) 5 RNC (Radio Network Controller) 7 handover optimization system 11 adjacent list optimization unit 12 adjacent list generation unit 41 network design information 42 cell monitoring information 61 target cell 62 adjacent cell 71 adjacent list optimization unit 110 cell selection unit 710 cell selection unit
- NMS Network Management System
- RNC Radio Network Controller
Abstract
Description
PS+OS<PT+OT (1)
式(1)中のPSはサービングセルの無線品質の測定結果であり、PTは、隣接セルの無線品質の測定結果である。LTEの場合、PS及びPTは、下りリファレンス信号の受信電力(RSRP:Reference Signal Received Power)又はRSRQ(Reference Signal Received Quality)である。RSRQは、総受信電力に対するRSRPの比率である。また、式(1)中のOSは、サービングセルの無線品質に対するオフセット値であり、サービングセルの下りリファレンス信号の無線品質に作用する。一方、OTは、隣接セルの無線品質に対するオフセット値であり、隣接セルの下りリファレンス信号の無線品質に作用する。つまり、隣接リストは、登録セル毎に異なるオフセットOT設定を保持することができる。オフセット値OTは、CIO(Cell Individual Offset)と呼ばれる。
PT-PS>THHO (2)
THHO=OS-OT (3)
図1は、本実施の形態に係るハンドオーバ最適化システム1を含むネットワークの構成例を示す図である。ハンドオーバ最適化システム1は、対象セル61に関する隣接リストの更新処理を行う。対象セル61の隣接リストは、対象セル61を管理する基地局2から移動端末(以下UE:User Equipment)3が受信可能な無線チャネルを用いて送信される。
(セル種別を考慮した登録セル選択の第1の例)
セル選択部110は、セル種別によって登録セルを選択する基準を変える。例えば、隣接マクロセルについては、第1の指標(e.g. UE3による検出数及びHO試行数の少なくとも一方)が大きいセルを優先的に登録セルとして選択する第1の基準を採用する。一方、その他の種別の隣接セル(例えば隣接ピコセル)については、第2の指標(e.g.HO失敗数、HO失敗率、又は失敗数の占有率)が大きいセルを優先的に登録セルとして選択する第2の基準を採用する。なお、第1及び第2の指標は、それぞれ複数の指標を含んでもよい。この場合、マクロセル用の指標の組合せとその他の種別の隣接セル用の指標の組合せが異なっていればよい。また、セル選択部110は、セル種別に依らず同一の指標を用いるが、登録セルを選ぶ際に当該指標と比較する閾値をセル種別によって変更してもよい。例えば、共通の指標として"UE3による検出数"を用いる場合、隣接マクロセル用には高い閾値を適用し、その他の隣接セル(例えば隣接ピコセル)用には、マクロセルに比べて低い閾値を採用すればよい。
続いて、セル種別を考慮した登録セル選択の第2の例を説明する。セル選択部110は、少なくとも1つのセル種別(例えばピコセル)のために、隣接リストの最大登録可能数NCLmaxの一部を登録枠(予約枠)として確保する。言い換えると、セル選択部110は、少なくとも1つのセル種別(例えばマクロセル)に登録上限数(隣接リストの最大登録可能数NCLmaxから予約枠の数を引いた値)を設定する。また、セル選択部110は、隣接リストの最大登録可能数NCLmaxを分割することでセル種別毎の登録枠を設定し、セル種別毎に各々の登録枠の範囲内で登録セルを選択してもよい。これらによれば、仮にセル種別によらずに共通の基準で登録セルを選択する場合であっても、複数のセル種別のセル群を隣接リストに確実に登録することができる。
発明の実施の形態1で述べたセル選択指標(CSI)は一例に過ぎない。また、複数の指標を組み合わせて用いてもよい。例えば、隣接ピコセルに関しては、測定報告数が閾値を超えているセルの中からHO失敗率の大きいものを選ぶといった選択基準を採用してもよい。
上述した発明の実施の形態1では、対象セル61から隣接セル62への外向き(outbound)の"HO失敗数"、"HO失敗率"、又は"失敗数の占有率"をセル選択指標として用いる例に言及した。このように、対象セル61から隣接セル62へのoutboundハンドオーバの失敗数又は失敗率が相対的に大きいセルを優先的に選択する基準を用いて登録セルを選択することは、非特許文献2に記載されていない事項である。したがって、ここでは、セルサイズの違いに応じて定められたセル種別を考慮することを必須要素とすることなく、隣接セル62へのoutboundハンドオーバの失敗数又は失敗率を指標とした登録セルの選択を行う参考例について説明する。
対象セルを管理する基地局によって無線送信される隣接リストの最適化を行う隣接リスト最適化装置であって、
前記対象セルを除く複数の他セルのうち、前記対象セルから前記他セルへの外向きのハンドオーバの失敗数又は失敗率が相対的に大きいセルを優先的に選択する第1の基準を用いて、前記隣接リストに登録される複数の登録セルを選択するセル選択手段を備える、隣接リスト最適化装置。
前記失敗率は、前記対象セルからの外向きのハンドオーバの試行数に対する失敗数の割合、又は前記対象セルからの外向きのハンドオーバの失敗数の総和に対する、前記他セルへの外向きのハンドオーバの失敗数の割合である、付記1に記載の隣接リスト最適化装置。
前記セル選択手段は、さらに、セルサイズの違いに応じて定められたセル種別を考慮して、前記複数の登録セルを選択する、付記1又は2に記載の隣接リスト最適化装置。
前記セル種別は、第1のセル種別と、前記第1のセル種別で示される第1のセルとはセルサイズの異なる第2のセルを示す第2のセル種別とを含み、
前記セル選択手段は、
前記複数の他セルに含まれる前記第1のセル群の中から、前記第1の基準に従って登録セルを選択し、
前記複数の他セルに含まれる前記第2のセル群の中から、前記第1の基準とは異なる第2の基準に従って登録セルを選択する、
付記1~3のいずれか1項に記載の隣接リスト最適化装置。
前記セル選択手段は、前記複数の他セルに含まれる前記第1のセルの数及び前記第2のセルの数のうちいずれか一方が前記隣接リストの最大登録可能数を超える場合であっても、前記第1及び第2のセルが共に前記隣接リストに登録されるように、前記複数の登録セルを選択する、付記4に記載の隣接リスト最適化装置。
前記第2のセルは、前記第1のセルよりセルサイズの大きいセルであって、
前記第2の基準は、前記第2のセル群のうち、前記対象セルから前記第2のセルへの外向きのハンドオーバが多く発生すると予測されるセルを前記登録セルとして優先的に選択することを含む、付記4又は5に記載の隣接リスト最適化装置。
前記第2のセルは、前記第1のセルよりセルサイズの大きいセルであって、
前記第2の基準は、前記第2のセル群のうち、移動端末による検出数、前記対象セルから前記第2のセルへの外向きのハンドオーバの試行数、又は移動端末の再接続数が相対的に大きいセルを前記登録セルとして優先的に選択することを含む、付記4又は5のいずれか1項に記載の隣接リスト最適化装置。
前記セル選択手段は、
前記第2のセル群の中から登録セルを優先的に選択し、
前記隣接リストに登録できるセルの残数の範囲内で、前記第1のセル群の中から登録セルを選択する、
付記4~7のいずれか1項に記載の隣接リスト最適化装置。
前記セル選択手段は、
前記第1の基準に従って、前記複数の他セルの中から登録セルを優先的に選択するとともに、
前記隣接リストに登録可能なセルの残数の範囲内で、前記第1の基準とは異なる第2の基準に従って、前記複数の他セルのうち未選択のセル群の中から登録セルを選択する、
付記1又は2に記載の隣接リスト最適化装置。
前記セル選択手段は、前記隣接リストの最大登録可能数より小さい所定数の範囲内で、前記第1の基準に基づく登録セルの選択を行う、付記9に記載の隣接リスト最適化装置。
付記1~10のいずれか1項に記載の隣接リスト最適化装置と結合され、
前記複数の登録セルの情報を含む隣接リストを生成する隣接リスト生成装置。
付記11に記載の隣接リスト生成装置と結合され、
前記複数の登録セルの情報を含む隣接リストを無線送信するよう構成された基地局装置。
2 基地局
3 移動端末
4 ネットワーク管理システム(NMS: Network Management System)
5 RNC(Radio Network Controller)
7 ハンドオーバ最適化システム
11 隣接リスト最適化部
12 隣接リスト生成部
41 ネットワーク設計情報
42 セル監視情報
61 対象セル
62 隣接セル
71 隣接リスト最適化部
110 セル選択部
710 セル選択部
Claims (37)
- 対象セルを管理する基地局によって無線送信される隣接リストの最適化を行う隣接リスト最適化装置であって、
セルサイズの違いに応じて定められたセル種別を考慮して、前記対象セルを除く複数の他セルの中から、前記隣接リストに登録される複数の登録セルを選択するセル選択手段を備える、隣接リスト最適化装置。 - 前記セル種別は、第1のセル種別と、前記第1のセル種別で示される第1のセルとはセルサイズの異なる第2のセルを示す第2のセル種別とを含む、請求項1に記載の隣接リスト最適化装置。
- 前記セル選択手段は、前記複数の他セルに含まれる前記第1のセルの数及び前記第2のセルの数のうちいずれか一方が前記隣接リストの最大登録可能数を超える場合であっても、前記第1及び第2のセルが共に前記隣接リストに登録されるように、前記複数の登録セルを選択する、請求項2に記載の隣接リスト最適化装置。
- 前記セル選択手段は、
前記複数の他セルに含まれる前記第1のセル群の中から、第1の基準に従って登録セルを選択し、
前記複数の他セルに含まれる前記第2のセル群の中から、前記第1の基準とは異なる第2の基準に従って登録セルを選択する、
請求項2又は3に記載の隣接リスト最適化装置。 - 前記第2のセルは、前記第1のセルよりセルサイズの小さいセルであって、
前記第2の基準は、前記第2のセル群のうち、前記対象セルから前記第2のセルへの外向きのハンドオーバの失敗数又は失敗率が相対的に大きいセルを前記登録セルとして優先的に選択することを含む、請求項4に記載の隣接リスト最適化装置。 - 前記失敗率は、前記対象セルからの外向きのハンドオーバの試行数に対する失敗数の割合、又は前記対象セルからの外向きのハンドオーバの失敗数の総和に対する、前記第2のセルへの外向きのハンドオーバの失敗数の割合である、請求項5に記載の隣接リスト最適化装置。
- 前記第2のセルは、前記第1のセルよりセルサイズの小さいセルであって、
前記第2の基準は、前記第2のセル群のうち、移動端末の平均的な滞在時間が相対的に短いセルを前記登録セルとして優先的に選択することを含む、請求項4に記載の隣接リスト最適化装置。 - 前記第1のセルは、前記第2のセルよりセルサイズの大きいセルであって、
前記第1の基準は、前記第1のセル群のうち、前記対象セルから前記第1のセルへの外向きのハンドオーバが多く発生すると予測されるセルを前記登録セルとして優先的に選択することを含む、請求項4~7のいずれか1項に記載の隣接リスト最適化装置。 - 前記第1のセルは、前記第2のセルよりセルサイズの大きいセルであって、
前記第1の基準は、前記第1のセル群のうち、移動端末による検出数、前記対象セルから前記第1のセルへの外向きのハンドオーバの試行数、又は移動端末の再接続数が相対的に大きいセルを前記登録セルとして優先的に選択することを含む、請求項4~7のいずれか1項に記載の隣接リスト最適化装置。 - 前記セル選択手段は、
前記第1のセル群の中から登録セルを優先的に選択し、
前記隣接リストに登録できるセルの残数の範囲内で、前記第2のセル群の中から登録セルを選択する、
請求項2~9のいずれか1項に記載の隣接リスト最適化装置。 - 前記セル選択手段は、前記隣接リストの最大登録可能数より小さい所定数の範囲内で、前記第1のセル群の中から登録セルを選択する、請求項10に記載の隣接リスト最適化装置。
- 前記第1のセル群からの登録セルの選択は、移動端末による検出数が多いセルから順に選択することを含む、請求項10又は11に記載の隣接リスト最適化装置。
- 前記隣接リストは、前記対象セルから前記登録セルへの外向きのハンドオーバ、又は通信開始時に接続するセルの選択を制御するために設定される、前記登録セル毎の制御パラメータを含む、請求項1~12のいずれか1項に記載の隣接リスト最適化装置。
- 前記制御パラメータは、移動端末によって測定される前記登録セルの受信電力または信号対干渉波比に対して付加されるオフセット値を含む、請求項13に記載の隣接リスト最適化装置。
- 前記セル選択手段は、前記対象セルの通信負荷が閾値以上の場合に、前記セル種別を考慮したセル選択処理を行う、請求項1~14のいずれか1項に記載の隣接リスト最適化装置。
- 請求項1~15のいずれか1項に記載の隣接リスト最適化装置と結合され、
前記複数の登録セルの情報を含む隣接リストを生成する隣接リスト生成装置。 - 請求項16に記載の隣接リスト生成装置と結合され、
前記複数の登録セルの情報を含む隣接リストを無線送信するよう構成された基地局装置。 - 対象セルを管理する基地局によって無線送信される隣接リストの最適化を行う隣接リストの最適化方法であって、
セルサイズの違いに応じて定められたセル種別を考慮して、前記対象セルを除く複数の他セルの中から、前記隣接リストに登録される複数の登録セルを選択することを備える、隣接リストの最適化方法。 - 前記セル種別は、第1のセル種別と、前記第1のセル種別で示される第1のセルとはセルサイズの異なる第2のセルを示す第2のセル種別とを含む、請求項18に記載の方法。
- 前記登録セルの選択は、前記複数の他セルに含まれる前記第1のセルの数及び前記第2のセルの数のうちいずれか一方が前記隣接リストの最大登録可能数を超える場合であっても、前記第1及び第2のセルが共に前記隣接リストに登録されるように、前記複数の登録セルを選択することを含む、請求項19に記載の方法。
- 前記登録セルの選択は、
前記複数の他セルに含まれる前記第1のセル群の中から、第1の基準に従って登録セルを選択し、
前記複数の他セルに含まれる前記第2のセル群の中から、前記第1の基準とは異なる第2の基準に従って登録セルを選択すること、
を含む請求項19又は20に記載の方法。 - 前記第2のセルは、前記第1のセルよりセルサイズの小さいセルであって、
前記第2の基準は、前記第2のセル群のうち、前記対象セルから前記第2のセルへの外向きのハンドオーバの失敗数又は失敗率が相対的に大きいセルを前記登録セルとして優先的に選択することを含む、請求項21に記載の方法。 - 前記失敗率は、前記対象セルからの外向きのハンドオーバの試行数に対する失敗数の割合、又は前記対象セルからの外向きのハンドオーバの失敗数の総和に対する、前記第2のセルへの外向きのハンドオーバの失敗数の割合である、請求項22に記載の方法。
- 前記第2のセルは、前記第1のセルよりセルサイズの小さいセルであって、
前記第2の基準は、前記第2のセル群のうち、移動端末の平均的な滞在時間が相対的に短いセルを前記登録セルとして優先的に選択することを含む、請求項21に記載の方法。 - 前記第1のセルは、前記第2のセルよりセルサイズの大きいセルであって、
前記第1の基準は、前記第1のセル群のうち、前記対象セルから前記第1のセルへの外向きのハンドオーバが多く発生すると予測されるセルを前記登録セルとして優先的に選択することを含む、請求項21~24のいずれか1項に記載の方法。 - 前記第1のセルは、前記第2のセルよりセルサイズの大きいセルであって、
前記第1の基準は、前記第1のセル群のうち、移動端末による検出数、前記対象セルから前記第1のセルへの外向きのハンドオーバの試行数、又は移動端末の再接続数が相対的に大きいセルを前記登録セルとして優先的に選択することを含む、請求項21~25のいずれか1項に記載の方法。 - 前記登録セルの選択は、
前記第1のセル群の中から登録セルを優先的に選択し、
前記隣接リストに登録できるセルの残数の範囲内で、前記第2のセル群の中から登録セルを選択すること、
を含む請求項19~25のいずれか1項に記載の方法。 - 前記登録セルの選択は、前記隣接リストの最大登録可能数より小さい所定数の範囲内で、前記第1のセル群の中から登録セルを選択することを含む、請求項27に記載の方法。
- 隣接リストの最適化方法をコンピュータに行わせるためのプログラムを格納した非一時的なコンピュータ可読媒体であって、
前記最適化方法は、セルサイズの違いに応じて定められたセル種別を考慮して、前記隣接リストを送信する基地局によって管理される対象セルを除く複数の他セルの中から、前記隣接リストに登録される複数の登録セルを選択することを備える、
非一時的なコンピュータ可読媒体。 - 前記セル種別は、第1のセル種別と、前記第1のセル種別で示される第1のセルとはセルサイズの異なる第2のセルを示す第2のセル種別とを含む、請求項29に記載の非一時的なコンピュータ可読媒体。
- 前記登録セルの選択は、前記複数の他セルに含まれる前記第1のセルの数及び前記第2のセルの数のうちいずれか一方が前記隣接リストの最大登録可能数を超える場合であっても、前記第1及び第2のセルが共に前記隣接リストに登録されるように、前記複数の登録セルを選択することを含む、請求項30に記載の非一時的なコンピュータ可読媒体。
- 前記登録セルの選択は、
前記複数の他セルに含まれる前記第1のセル群の中から、第1の基準に従って登録セルを選択し、
前記複数の他セルに含まれる前記第2のセル群の中から、前記第1の基準とは異なる第2の基準に従って登録セルを選択すること、
を含む請求項30又は31に記載の非一時的なコンピュータ可読媒体。 - 前記第2のセルは、前記第1のセルよりセルサイズの小さいセルであって、
前記第2の基準は、前記第2のセル群のうち、前記対象セルから前記第2のセルへの外向きのハンドオーバの失敗数又は失敗率が相対的に大きいセルを前記登録セルとして優先的に選択することを含む、請求項32に記載の非一時的なコンピュータ可読媒体。 - 前記第2のセルは、前記第1のセルよりセルサイズの小さいセルであって、
前記第2の基準は、前記第2のセル群のうち、移動端末の平均的な滞在時間が相対的に短いセルを前記登録セルとして優先的に選択することを含む、請求項32に記載の非一時的なコンピュータ可読媒体。 - 前記第1のセルは、前記第2のセルよりセルサイズの大きいセルであって、
前記第1の基準は、前記第1のセル群のうち、前記対象セルから前記第1のセルへの外向きのハンドオーバが多く発生すると予測されるセルを前記登録セルとして優先的に選択することを含む、請求項32~34のいずれか1項に記載の非一時的なコンピュータ可読媒体。 - 前記第1のセルは、前記第2のセルよりセルサイズの大きいセルであって、
前記第1の基準は、前記第1のセル群のうち、移動端末による検出数、前記対象セルから前記第1のセルへの外向きのハンドオーバの試行数、又は移動端末の再接続数が相対的に大きいセルを前記登録セルとして優先的に選択することを含む、請求項32~35のいずれか1項に記載の非一時的なコンピュータ可読媒体。 - 前記登録セルの選択は、
前記第1のセル群の中から登録セルを優先的に選択し、
前記隣接リストに登録できるセルの残数の範囲内で、前記第2のセル群の中から登録セルを選択すること、
を含む請求項30~36のいずれか1項に記載の非一時的なコンピュータ可読媒体。
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JP2016220045A (ja) * | 2015-05-20 | 2016-12-22 | 株式会社Nttドコモ | 無線基地局 |
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JP2022158832A (ja) * | 2021-03-31 | 2022-10-17 | スターライト テクノロジーズ リミテッド | オープン無線アクセスネットワーク環境におけるリアルタイムハンドオーバートリガーのためのユーザー機器識別方法 |
Also Published As
Publication number | Publication date |
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EP2658313A1 (en) | 2013-10-30 |
CN103270791A (zh) | 2013-08-28 |
JP5942853B2 (ja) | 2016-06-29 |
JPWO2012086108A1 (ja) | 2014-05-22 |
US20130316709A1 (en) | 2013-11-28 |
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