WO2006100401A1

WO2006100401A1 - Generating automatically list of neighbouring cells

Info

Publication number: WO2006100401A1
Application number: PCT/FR2006/050226
Authority: WO
Inventors: Mylène PISCHELLA; Delphine Lugara
Original assignee: France Telecom
Priority date: 2005-03-23
Filing date: 2006-03-14
Publication date: 2006-09-28
Also published as: FR2883695A1

Abstract

The invention concerns a device comprising a module (MG) for selecting in each of the meshes one of N best quantities, a module (ME) for estimating for each of the selections of N best quantities N ratios each respective of one of the selected N best quantities over the best quantity of the selection, a module (MS) for summing the estimated ratios for each cell pair constituted by the given cell and a selected cell, a central unit (UC) for ordering the sums of the ratios in ascending order, and a generator (GL) generating and storing an ordered list of selected cells having the highest sums of ratios, as neighbouring cells. The lists of cells capable of being generated are lists of intrafrequency, interfrequency and intersystem cells of a given cell.

Description

Automatic generation of neighbor cell list

The present invention relates to a method for automatically generating lists of neighboring cells of a given cell in a cellular radio network on a digitized mesh map background.

More particularly, it relates to a generation of intrafréquence, interfrequency and intersystem neighbor cell lists for a cell belonging to a third generation radio communication network (3GPP) of the Universal Mobile Telecommunications System (UMTS) type.

In the state of the art, cell list generating systems use physical quantities measured by mobile terminals and retransmitted by base station controllers or supervisory entities such as operation and maintenance centers. Networks are initialized with unoptimized neighbor cell lists, and systems generate and update neighboring cell lists only when new measured physical quantities are available. With the current systems, each time the radio network is changed, the lists must be optimized again, which consumes time and resources.

In addition, none of the current systems order cells in neighboring cell lists. Therefore, it is impossible to optimize the use of these lists in radiocommunication networks.

The object of the invention is to overcome the aforementioned drawbacks by automatically generating an ordered list of neighboring cells in a cellular radio network from simulation data, so as to reconfigure the network automatically and quickly each time it is modified and Rapidly improve mobile device transfers between cells that directly depend on the establishment of neighboring cell lists.

To achieve this objective, a method for automatically generating a list of neighboring cells of a given cell in a cellular radio network on a digitized mesh map background comprises the steps of: for each of the meshes, select N best relative magnitudes respectively at N cells of the network and simulated at a position of the mobile terminal assumed to be located in the mesh, N being an integer, estimating for each of the selections of N best magnitudes, N ratios each of a respective one of N magnitudes selected on the best magnitude of the selection, for each cell pair consisting of the given cell and a selected one of the N cells, summing the estimated ratios, and generating, ordering and storing a list of a predetermined number of selected cells having the largest amounts of reports, as neighboring cells of the given cell. The list of neighboring cells of the given cell can be used to determine a set of active cells of a terminal located in the given cell, by measuring magnitudes between the terminal and each of the cells in the list.

Scheduling the selected cells in the list results in reducing the number of neighboring cells allocated to a cell by keeping only neighboring cells with the largest sums of ratios. This reduction in the size of the lists reduces the occupation in memory by the lists and the number of quantities to be measured between the terminal and cells.

According to one embodiment of the invention, the selected cells have different frequencies of the frequency of the given cell, and the given cell is one of the cells of a set of active cells defined in each of the cells. The generated list is then an ordered list of inter-frequency cells.

According to another embodiment of the invention, the selected cells are included in radio communication networks different from the radiocommunications network of the given cell, and the given cell is one of the cells of a set of active cells defined in each of the sts. The generated list is then an ordered list of intersystem cells.

According to another characteristic of the invention, if the simulated size of the given cell is one of the N best magnitudes, the given cell and the selected cells have an identical frequency, and each estimated ratio is multiplied by the square root of the ratio. of the respective cell size selected on the size of the cell given when the respective magnitude of the selected cell is smaller than the size of the given cell and the ratio of the size of the given cell to the respective magnitude of the selected cell when the respective magnitude of the selected cell is greater than the magnitude of the the given cell. The generated list is then an ordered list of intraframe cells.

The invention also relates to a device for automatically generating a list of neighboring cells of a given cell in a cellular radio network on a digitized mesh map base, the device comprising a means for selecting in each of the meshes, N best magnitudes relative respectively to N cells of the network and simulated at a position of the mobile terminal assumed to be in the cell, N being an integer, the given cell being able to belong to a list of neighboring cells predetermined frequency of an active cell with which the mobile terminal is in communication, or the simulated size of the given cell being one of the N best magnitudes. The device also comprises: means for estimating, for each of the selections of N best magnitudes, N ratios each of the respective one of the N magnitudes selected on the best size of the selection, a means for summing the estimated ratios for each pair of cells constituted by the given cell and a cell selected from the N cells, means respectively for generating, ordering and storing an ordered list of a predetermined number of selected cells having the largest sums of ratios, as neighboring cells of the given cell.

Finally, the invention relates to a computer program adapted to be implemented in a generation device according to the invention. The program includes program instructions which, when the program is loaded and executed on said server, perform the steps of the generation method according to the invention.

Other features and advantages of the present invention will emerge more clearly on reading the following description of several preferred embodiments of the invention, given by way of non-limiting examples, with reference to the corresponding appended drawings in which:

FIG. 1 is a schematic block diagram of a neighbor cell list generating device according to the invention; Fig. 2 is a mesh map background showing a simulation environment for generating neighbor cell lists according to the invention;

FIG. 3 is an illustration of intra-frequency, inter-frequency, and intersystem cell change according to the invention; and

FIG. 4 is an algorithm of a neighbor cell list generating method according to the invention. The neighbor cell list generation device D according to the invention mainly comprises a central unit UC, a size selection module MG, an estimation module ME, a summation module MS, a neighbor cell list generator GL. , an SG magnitude simulator and a BD database.

In the following description, an active cell of a mobile terminal is the cell whose base station is in communication with the terminal.

The method according to the invention is implemented for example in the form of software implemented in the generation device D, such as a personal computer, which contains the database BD including data relating to data networks. radiocommunications and to quantities. In a variant, the database BD is in a database server connected to the device D locally or remotely through a telecommunications network of the Internet type.

In another variant, the quantity simulator SG is in a device of the computer type and distinct from the device D according to the invention. The SG simulator is linked locally or remotely to the database BD.

The device D may communicate with fixed network entities of a UMTS type cellular radio network, such as an OMC (Operation and Maintenance Center) maintenance center and terrestrial interfaces between RNC base station controllers (Radio Network Controller) for a UMTS network in order to quickly transmit lists of neighboring cells generated according to the invention when the network is at least modified.

The neighbor cell list generation method mainly comprises eight steps E1 to E8, as shown in FIG.

Initially in step E1, an operator of the device D determines a geographical zone Z comprising cells of the UMTS cellular radio network for which lists of neighboring cells are to be generated. When the device D is a computer, the determined geographical area Z is defined, for example, using the mouse of the computer to plot and move a closed curve of variable size on a digitized map background displayed on the screen. computer screen. The characteristics of the zone Z thus defined and having a mixed line outline in FIG. 2 are digitized and recorded in the database BD. In this database, the cells are identified by cell identifiers.

Initially at step E2, the central unit UC cuts the geographical zone Z and thus the basemap into polygonal meshes (surface elements), for example square meshes m of identical size, as shown in FIG. If zone Z is urban, the mesh side is for example from 5 m to 25 m approximately. In step E3, the quantity simulator SG simulates quantities as if they were measured in a mobile terminal T located in a mesh m. The simulated quantities generally correspond to reception powers or estimates of the radio quality of signals that are transmitted according to Downlinks from BS from the cellular network to the mobile terminal T. As is known, receiving a given transmit power signal from a base station helps define a cell of the network. radiocommunications which most often covers several meshes.

The simulator SG assumes that the mobile terminal T is located in a mesh m to determine the simulated quantities that could be received by the mobile terminal with a sufficient level. Simulated quantities provided by the simulator SG can be based on extrapolation of physical quantities actually measured in geographical area Z, in particular by mobile terminals and retransmitted by base station controllers or supervisory entities, and / or from a predetermined digitized propagation pattern. The simulator SG has in the database BD digital data of geographical points regularly distributed in grid in the area and each defined for example by longitude, latitude and altitude, road data, roads and hydrographic, data d establishment of buildings, etc. The simulated quantities are stored in the database BD.

In a variant, the quantities are predetermined independently of the list generating method and stored in the device BD database.

For a UMTS radio network, the quantities correspond to a received power measured in the common beacon channel on the CPICH RSCP (Received Signal Code Power on Common Pilot Channel) or an energy ratio of an element of code (chip) measured on a power spectral density in a useful band CPICH E _c / N _o . For GSM radio networks, the quantities correspond to the standardized "RXLEV" parameters indicating the signal field level received by the mobile terminal from among 64 levels expressed in dBm.

The quantities simulated by the simulator SG are deduced from extrapolated and / or modeled interfering magnitudes which relate to physical channels in the downward direction which are transmitted at frequencies carrying cells of the geographical zone Z different from the frequency of a cell. active which the base station is in communication with the mobile terminal T and which most often covers at least in part a given mesh in which the mobile terminal T is supposed to be. For the interfrequency variables, the method according to the invention generates lists of neighboring cells called neighboring inter-frequency cells. A list of neighboring inter-frequency cells is used in the management of cell changes (handover) between cells of the same radio network but of different frequency, as shown by the arrows 1 in FIG. 3. In the preferred embodiment of the invention the neighboring inter-frequency cells and the active cell are cells of a UMTS common radio communication network.

In a first variant, the quantities simulated by the simulator SG are deduced from extrapolated and / or modeled intersystem quantities which relate to physical channels of cells of the geographical zone Z in the downward direction belonging to another radio network than that of the active cell whose station base is in communication with the mobile terminal T. For intersystem (internetwork) magnitudes, the method according to the invention generates lists of neighboring cells called intersystem neighboring cells. A list of intersystem neighboring cells is used in the management of cell changes between cells of different radio networks, as shown by arrow 2 in Figure 3. For example, the active cell is a cell of a radiocommunications network UMTS and neighboring cells are cells of a GSM radio network.

In a second variant, the quantities simulated by the simulator SG are deduced from extrapolated and / or modeled intrafréquence quantities which relate to physical channels of cells of the geographical zone Z in the downward direction which are transmitted at the same carrier frequency as that of the cell or active cells whose base stations are in communication with the mobile terminal T. For intrafréquence quantities, the method according to the invention generates lists of neighboring cells said intra-frequency neighboring cells. A list of intra-frequency neighboring cells is used in the management of cell changes between cells of the same frequency, as shown by arrow 3 in FIG. 3. In a preferred embodiment of the invention, the intra-frequency neighboring cells, including the given cell, and the active cell are cells of the UMTS radio network.

The following steps E4 to E8 are applied to a given cell Ci of the network of radiocommunications and are to be repeated for each of the cells, as a given cell, of the geographical zone Z for which a list of neighboring cells is to be generated. In step E4, for each m of the meshes of the geographical zone Z, the quantity selection module MG selects N best simulated quantities relating respectively to N cells Cj of the radio network when the given cell Ci is one of the cells a set of active cells defined in each of the cells, N being an integer. The step of selecting N best magnitudes comprises an ordering of magnitudes, relating respectively to cells Cj of the network and simulated at a position of the mobile terminal T supposedly located in the mesh m, defining a bounded range of quantities, a selection of the magnitude one of the bounds of the defined interval, and a selection of said selected magnitude and NI magnitudes closest to said selected magnitude, or N selected variables. Said selected quantity is the best quantity of the selection and the N best quantities are said selected quantity and the NI quantities closest to said selected quantity. The N magnitudes are selected from simulated magnitudes in cells that are considered to be measured at a position of the mobile terminal T assumed to be in the mesh m. For example, when quantities are relative to powers, said selected magnitude corresponds to the largest magnitude of the bounded range. On the other hand, when quantities are relative to attenuations, said selected size corresponds to the smallest magnitude of bounded interval. The selected cells Cj have different frequencies of the frequency of the given cell and the given cell

Ci is one of the cells of a set of active cells defined in each of the cells. The selection of cells is stored in the database BD.

In the first simulated intersystem variant, the selected cells Cj are included in radio communication networks different from that of the given cell Ci and the given cell Ci is one of the cells of a set of active cells defined in each of the cells. mesh.

In the second variant with simulated intra-frequency quantities, for each m of the meshes, the selection module MG selects N best simulated intrafréquence quantities if the simulated size of the given cell Ci is one of the N best magnitudes. In this variant, the base stations of the given cell Ci and the selected cells Cj emit at an identical frequency.

In step E5, for each of the selections of N best magnitudes simulated and therefore for each m of meshes, the estimation module ME determines and stores the best size of the N best magnitudes of the selection, and estimates N ratios each of the a respective one of the N magnitudes selected on the best determined quantity of the selection. The quantities are expressed in linear value.

In a variant in step E5, the selection module MG selects M magnitudes greater than a predetermined threshold from among the N best magnitudes selected, M being an integer less than or equal to N, and the estimation module ME determines the the best magnitudes of the best magnitudes and only estimates the ratios of the magnitudes selected on the best magnitudes of the magnitudes. In another variant that can be combined with the preceding variant as well as with the first variant but not with the second variant, the ratios are estimated only when the best size of the neighboring cells of a set of active cells defined for the mesh m is below a predetermined threshold. This other variant limits the number of relevant meshes to be processed during the determination of intersystem and interfrequency cells. In step E6, the summation module MS sums the estimated ratios for each cell pair constituted by the given cell Ci and a selected cell Cj. The summation module MS stores the sums of reports in the database BD. In step E7, the neighboring cell list generator GL generates a list of a predetermined number of selected cells Cj having the largest sums of ratios, as neighboring cells of the given cell Ci. The central processing unit UC orders and stores the generated list in the database BD in correspondence with the cell given in step

E8. The ordered list of neighboring cells generated relates to neighboring inter-frequency cells.

In the first variant, the ordered list of neighboring cells generated stored in the database BD is an ordered list of neighboring intersystem cells.

In the second variant, the ordered list of neighboring cells generated stored in the database BD is an ordered list of cells neighboring intrafrequency, that is to say of identical frequency, and the simulated size of the given cell is one of the N best magnitudes. To improve the generation of the intra-frequency neighboring cell list, each estimated ratio at step E5 is multiplied by the square root of the ratio of the respective cell size selected to the size of the given cell when the respective magnitude of the selected cell. is smaller than the size of the given cell and the ratio of the size of the given cell to the respective magnitude of the selected cell when the respective magnitude of the selected cell is larger than the size of the given cell, before being summed in step E6.

Thus, the generated lists are made available to the operators of radio networks and are stored in databases of the base station controllers or the maintenance centers, so that the handover by the mobile terminals are optimized .

The invention described herein relates to a method and a device for generating neighbor cell lists. In a preferred implementation, the steps of the method are determined by the instructions of a neighboring cell list generation program incorporated into a computing device D such as a computer. The program includes program instructions which, when said program is loaded and executed in the computing device whose operation is then controlled by the execution of the program, carry out the steps of the method according to the invention.

Accordingly, the invention also applies to a computer program, including a computer program on or in an information carrier, adapted to implement the invention. This program can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code such as in a partially compiled form, or in any other form desirable to implement the method according to the invention.

The information carrier may be any entity or device capable of storing the program. For example, the medium may comprise storage means or recording medium, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording medium, for example a floppy disk (floppy). say) or a hard drive.

On the other hand, the information medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention can in particular be downloaded to an Internet type network.

Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in carrying out the method according to the invention.

Claims

A method for automatically generating a list of neighboring cells of a given cell (Ci) in a cellular radio network on a digitized mesh backplane (Z), the method comprising the steps of: for each (m) of mesh, select N best magnitudes respectively relative to N cells (Cj) of the network and simulated at a position of the mobile terminal (T) assumed to be located in the mesh, N being an integer, estimating (E5) for each of the selections of N better magnitudes, N ratios each of a respective one of the N magnitudes selected on the best size of the selection, for each cell pair consisting of the given cell (Ci) and a selected cell (Cj) among the N cells, summing (E6 ) the estimated reports, generating (E7), ordering (E8) and storing a list of a predetermined number of selected cells (Cj) having the largest sums of reports, as a cell next to the given cell.

2 - Process according to claim 1, wherein the selected cells (Cj) have different frequencies of the frequency of the given cell (Ci), and the given cell (Ci) is one of the cells of a set active cells defined in each of the cells.

3 - Process according to claim 1, wherein the selected cells (Cj) are included in radio networks different from the radiocommunications network of the given cell (Ci), and the given cell (Ci) is one of the cells of a set of active cells defined in each of the cells.

4 - Process according to claim 2 or 3, wherein the reports are estimated only when the best size of a set of active cells defined for the mesh (m) is less than a predetermined threshold.

5 - Process according to claim 1, wherein the simulated size of the given cell is one of the N best magnitudes, the given cell

(Ci) and the selected cells (Cj) have an identical frequency, and each estimated ratio is multiplied by the square root of the ratio of the respective magnitude of the selected cell to the size of the given cell when the respective magnitude of the selected cell is smaller than the size of the given cell and the ratio of the size of the given cell to the respective magnitude of the selected cell when the respective magnitude of the selected cell is larger than the size of the given cell.

6 - Process according to any one of claims 1 to 5, comprising a selection of M magnitudes greater than a predetermined threshold among the N best magnitudes selected, M being an integer less than or equal to N, the step of estimating estimating only the ratios of the magnitudes selected on the best size of the magnitudes. 7 - Device for automatically generating a list of neighboring cells of a given cell (Ci) in a cellular radio network on a digitized mesh backplane (Z), the device comprising: means (MG) for selecting in each (m) meshes, N best magnitudes relative respectively to N cells (Cj) of the network and simulated at a position of the mobile terminal (T) assumed to be located in the mesh, N being an integer, means (ME) for estimating for each of the selections of N best magnitudes, N ratios each of a respective one of the N magnitudes selected on the best size of the selection, means (MS) for summing the estimated ratios for each cell pair constituted by the given cell (Ci ) and a selected cell (Cj) among the N cells, and means respectively for generating (GL), ordering (UC) and storing (UC) a list of a predetermined number of selected cells. es with the largest sums of reports, as the given cell to neighboring cells.

8 - Computer program on an information carrier for automatically generating a list of neighboring cells of a given cell (Ci) in a radio network on a base map

(Z) digitized mesh, said program having program instructions which when said program is loaded and executed in a computing device (D), perform the steps of: for each (m) of the meshs, select N best quantities relating respectively to N cells (Cj) of the network and simulated at a position of the mobile terminal (T) assumed to be located in the mesh, N being an integer, estimating (E5) for each selections of N best magnitudes, N ratios each of a respective one of the N magnitudes selected on the best size of the selection, for each cell pair constituted by the given cell (Ci) and a selected cell (Cj) among the N summing cells (E6) the estimated ratios, and generating (E7), ordering (E8) and storing a list of a predetermined number of selected cells (Cj) having the largest sums of ratios, as neighboring cells of the cell given.