Determining cell boundaries for operation management in a radio communication system

BACKGROUND OF THE INVENTION

0001The present invention relates to an operation management system of a radio communication system and a method thereof, and an operation management apparatus and a program to be employed for it, and more particularly to an operation management technique in a wireless LAN (Local Area Network) including a plurality of wireless base stations.

0002Conventionally, as a tool for displaying setting/statistical information of the wireless LAN, there has been known a management tool of a wireless LAN access point (AP) (which is often installed as a Web server within the AP). This tool makes it possible to obtain statistical information associated with an operation such as a packet number to be transmitted/received in the AP or an error packet number, or information of a channel in use. Acquiring and analyzing this statistical numerical information allows an operational situation of the above wireless LAN to be grasped; however the analysis demands high technical abilities and experience. That is, only based upon the numerical value of the statistical information, it is not easy to determine whether the operational situation is good or bad from information acquired by an administrator.

0003Also, as a technology of visually displaying the operational situation, there has been known the technology disclosed in <patcit id="pcit0001" dnum="JPP199893616A"><text>JP-P-1998-93616 A</text></patcit>, in which the effect that an interference situation in the AP was graphed and displayed according to its interference ratio was described, and its display example is shown in <figref idref="f0017">Fig. 17</figref>. The use situation of a wireless medium in one certain AP, which is divided into three kinds of a situation where an appliance belonging to the above AP (its own group) is used, a situation where an appliance belonging to the other AP (other group) is used and a noise situation, is displayed according to respective ratios for which these situations account. The administrator, who views the display as shown in <figref idref="f0017">Fig. 17</figref>, thereby to be able to easily grasp that a ratio at which the appliance belonging to the above AP is used is low or a ratio of the noise is high, can recognize that the operation is a problem.

0004Based upon this recognition of the problem, a countermeasure of removing a noise source or the like is taken responding to a necessity.

0005However, the technology of <patcit id="pcit0002" dnum="JPP199893616A"><text>JP-P1998-93616A</text></patcit>, which is capable of easily grasping whether the interference situation associated with a single AP is good or bad, is not able to go so far as to grasp a range in which the above operational situation (interference situation) exerts an influence. Also, a wireless LAN system, in which a plurality of the APs are installed and this plurality of the APs are employed, thereby to cover the area range to a some extent, is taken into consideration, in which the problem exists that the situation of the entirety of the system that is comprised of a plurality of the APs is impossible to grasp simultaneously. For example, in a case where the display as shown in <figref idref="f0018">Fig. 18</figref> was generated AP by AP, it is sometimes determined that a plurality of the APs are a problem respectively. At this moment, as a method of deciding a priority order in which the countermeasure is taken, it can be considered to employ an influence range of the AP, i.e. a space of a cell that is a coverage range; however the problem exists that it is impossible to make a determination only with the display as shown in <figref idref="f0018">Fig. 18</figref>.

0006Also, in a case where a user who used a terminal made a report "performance of the LAN system deteriorated" to the administrator, the administrator has to investigate which AP the terminal of the above user makes a connection to because the display as shown in <figref idref="f0018">Fig. 18</figref> is output AP by AP. However, it takes labor and time to investigate the connection destination AP of the above terminal because the user who uses the terminal is never aware of the AP to which its own terminal is connected, so it is impossible to quickly cope with claims of the user.

0007Also, conventionally, by acquiring the numerical value of setting/statistic information, or by making a graph display of the interference situation, the administrator specified operational situation for each AP, and specified the AP that was a connection destination of the user's terminal, thereby to estimate the performance of the terminal. However, normally, it was difficult for the operational administrator to estimate the performances of the terminal because the user used the AP that was a connection destination of the terminal without being aware thereof.

0008This document mainly focuses on a system using fixed cells, and discloses possibilities to evaluate the electromagnetic coverage in each cell based on various communication data measured by the mobile units which are present in each cell. In order for the system to work, mobile units must be present in each cell, and they have to measure various communication parameters like for example signal strength, signal quality etc. and report these data to the serving base station for evaluation of the electromagnetic coverage. This system is unable to work without users, i. e. without mobile units being present. It will therefore not be possible to estimate the shape of a cell in which no mobile unit is present, for example when there is little traffic at night. Furthermore, this system and method need to evaluate a large amount of communication data from a possibly large number of mobile units, therefore requiring considerable computing capacities.

0009As further prior art reference is made to document <patcit id="pcit0003" dnum="US20020129138A1"><text>US 2002/0129138A1</text></patcit> as well as to <patcit id="pcit0004" dnum="US20030040318A1"><text>US 2003/0040318A1</text></patcit>.

Summary of the invention

0010It is therefore an object of the invention to provide an operation management system and an operation management method as well as as corresponding program allowing to determine the boundaries of each cell also in situations where no users are present and with less computational work.

0011Another aspect is to provide an operation management system of a radio communication system capable of, in a case of operating the wireless LAN system that covers a wide-range area by employing a plurality of the APs, visually displaying the operational situation based upon a load situation or an interference situation in each cell, a utilization situation of the wireless channel, etc. together with its influence range on an area map and a method thereof, and a program to be employed for it.

0012According to the invention this object is achieved by an operation management system according to claim 1, an operation management method according to claim 11 and a program according to claim 19. Advantageous embodiments are defined in dependent claims.

0013Thus, in the wireless LAN system for operating a plurality of the wireless base stations (Access Point: AP), each operational situation based upon a cell range of each AP and operational information of the wireless appliance in the above cell is grasped, and each cell range on the area map is caused to have a display aspect that coincided with the operational situation. Doing so allows the administrator to easily grasp the operational situation location by location, and to determine communication quality for each location, whereby the effect exists that it becomes easy to find factors of deterioration in performance.

BRIEF DESCRIPTION OF THE DRAWINGS

0014This and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and drawings, in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1</figref> is a system block diagram of one embodiment of the present invention;</li><li><figref idref="f0002">Fig. 2</figref> is a functional block diagram of a managing server 1 of <figref idref="f0001">Fig. 1</figref>;</li><li><figref idref="f0003">Fig. 3</figref> is a functional block diagram of a cell boundary computing server 2 of <figref idref="f0001">Fig. 1</figref>;</li><li><figref idref="f0004">Fig. 4</figref> is a process flowchart of the entirety of the invention;</li><li><figref idref="f0005">Fig. 5</figref> is a flowchart of a cell boundary determining process by a simulation;</li><li><figref idref="f0006">Fig. 6</figref> is a view for explaining a cell boundary determining method employing a radio-wave propagation simulation;</li><li><figref idref="f0007">Fig. 7</figref> is a view illustrating cell boundaries obtained by the cell boundary determining method of <figref idref="f0006">Fig. 6</figref>;</li><li><figref idref="f0008">Fig. 8</figref> is a flowchart of a cell boundary determining process by actual measurement;</li><li><figref idref="f0009">Fig. 9</figref> is a view for explaining one example of the cell boundary determining process by the actual measurement;</li><li><figref idref="f0010">Fig. 10</figref> is an operational flowchart of an operational information collecting/working process of the managing server 1;</li><li><figref idref="f0011">Fig. 11</figref> is a view illustrating a correspondence relation between the operational situation, and collected information necessary for it and its working/computing method;</li><li><figref idref="f0012">Fig. 12</figref> is a view illustrating a correspondence relation between the operational situation, and collected information necessary for it and its working/computing method;</li><li><figref idref="f0013">Fig. 13</figref> is a view illustrating an outline of the display in a displaying apparatus 3;</li><li><figref idref="f0014">Fig. 14</figref> is a view illustrating a specific example of the display in the displaying apparatus 3;</li><li><figref idref="f0015">Fig. 15</figref> is a system block diagram of another embodiment of the present invention;</li><li><figref idref="f0016">Fig. 16</figref> is a system block diagram of yet another embodiment of the present invention;</li><li><figref idref="f0017">Fig. 17</figref> is a view illustrating an example in a case of simultaneously displaying a plurality of classes of operational situations for each cell on one screen; and</li><li><figref idref="f0018">Fig. 18</figref> is a display example of an interference situation that is one example of the operational situation in the conventional wireless LAN management.</li></ul>

DETAILED DESCRIPTION OF THE INVENTION

0015Hereinafter, an embodiment of the present invention will be explain in details while making a reference to the accompanied drawings. <figref idref="f0001">Fig. 1</figref> is a view illustrating the entirety of the system that is an embodiment of the present invention. A reference to <figref idref="f0001">Fig. 1</figref> is made, in which the embodiment of the present invention is configured of a managing server 1, a cell boundary computing server 2, a displaying apparatus 3, access points (APs) 4a to 4c that are a plurality of wireless base stations, and a plurality of W (wireless) LAN terminals 5a to 5g.

0016The managing server 1 has functions of acquiring and retaining various kinds of operational information to be described later from the WLAN appliances (which are assumed to include the AP and the terminal), of causing the displaying apparatus 3 to display the operational situation with a predetermined method, and of retaining information of a cell boundary (a boundary of the range that the AP covers) that the cell boundary computing server 2 was caused to compute by providing necessary information hereto.

0017The displaying apparatus 3, which is installed in an identical apparatus to the managing server 1, or a remote location via a network, has a function of displaying the operational situation in a display aspect for which an instruction was given from the managing server 1. The cell boundary computing server 2, to which various kinds of the operational information of the WLAN appliances under operation are provided from the managing server 1, has a function of computing a range that each AP covers. The AP 4a to 4c and the WLAN terminals 5a to 5g, which are a general WLAN appliance respectively, have a function of providing various kinds of the operational information to the managing server. However, there is a case where only one of the AP and the terminal has a function of providing the operational information and the other has not the above function, depending upon the operational situation to be displayed on the displaying apparatus 3.

0018<figref idref="f0002">Fig. 2</figref> is a functional block diagram of the managing server 1. In <figref idref="f0002">Fig. 2</figref>, a communicating section 11 is for making communication with the cell boundary computing server 2, the displaying apparatus 3 and the APs 4a to 4c, and an information collecting section 12 is for collecting various kinds of operational information from the APs 4a to 4c and the terminals 5a to 5g. An information storing section 13 is a memory for storing information collected by the information collecting section 12, storing information worked by an information working section 14, and further, storing cell boundary information from the cell boundary computing server 2. A controlling section 15, which is a CPU for controlling each of these sections 11 to 14, executes a controlling operation with a program pre-stored in a ROM 16.

0019<figref idref="f0003">Fig. 3</figref>, which is a block diagram of the cell boundary computing server 2, exemplifies the block in a case of making a simulation of computation of the cell boundary. As shown in <figref idref="f0003">Fig. 3</figref>, the cell boundary computing server 2 has a communication section 21 for making communication with the managing server 1, a pass loss computing section 22, a received power computing section 23, a connection AP deciding section 24, a cell range determining section 25, a controlling section (CPU) 26 for controlling each of these sections, and a ROM 27 having an operational procedure of this controlling section 26 pre-stored as a program. Each of the sections 22 to 25 has a function of computing the cell boundary of each AP, and its details will be explained together with an operational flow to be described later.

0020<figref idref="f0004">Fig. 4</figref> is a flowchart illustrating an operation of the entirety of the embodiment of the present invention, which is divided broadly into three processes. That is, it has a cell boundary determining step S1 of clarifying the cell boundaries of a plurality of the APs, an operational information collecting/working step S2 of collecting various kinds of operational information from each WLAN appliance to work this collected information responding to a necessity and for finding the operational situation, and an operational situation displaying step S3 of partitioning a service area of the wireless LAN system for each coverage range (cell) of each AP to make a display and of deciding the display aspect within the coverage range of each AP responding to the operational situation found in the step S2 to display the operational situation on the area map having it reflected. Additionally, the step S1 is basically an operation of the cell boundary computing server 2, the step S2 is an operation of the managing server 1, and the step S3 is an operation of the displaying apparatus 3.

0021<figref idref="f0005">Fig. 5</figref> is a flowchart illustrating the details of the operation of the cell boundary determining step S1 of <figref idref="f0004">Fig. 4</figref>, and as a processing method for this cell boundary determining step, a method by a simulation and a method by actual measurement are listed; however at first the method by the simulation will be explained according to a flow of <figref idref="f0005">Fig. 5</figref>. The functional block of the cell boundary computing server 2 in this case is one shown in <figref idref="f0003">Fig. 3</figref>.

0022In a case of employing the simulation, thereby to find the cell boundary, the managing server 1 collects power transmitted from each of the APs 4a to 4c and an antenna gain by the information collecting section 12, and transmits them to the cell boundary computing server 2 (step S11). One example of the collected information in this case is shown in a right and upper part of <figref idref="f0005">Fig. 5</figref>. Additionally, if these values are to be used in a fixed manner, they may be pre-set within the cell boundary computing server 2.

0023As a technique of finding an arrival range of a radio wave that the AP transmits, the cell boundary computing server 2 employs a statistical technique of employing an estimation model in which the radio wave damps depending upon a distance, or a technique of taking into consideration an influence of a structure like a ray-tracing method. By employing these techniques, for example, as shown in <figref idref="f0006">Fig. 6</figref>, a pass loss (propagation loss) from each of the APs 4a to 4c at an arbitrary observation point A (one of a plurality of minute areas to be obtained by partitioning the above service area in a lattice shape) within the service area (which is shown in a rectangular shape in the figure) of the WLAN that is an object of operation is estimated in the pass loss computing section 22 (step S12), and by employing the transmitted power and the antenna gain obtained in the step S11, power received from each AP position (transmitting point) at the observation point A is computed by the received power computing section 23 (step S13).

0024And, the connection AP deciding section 24 decides that the AP that obtains maximum received power at the observation point A is a connection AP at this observation point A (step S14). In <figref idref="f0006">Fig. 6</figref>, the connection AP at the observation point A is the AP 4a. Herein, the connection AP is explained, in which each terminal carries out an association (connection process) for one AP because it makes communication in the wireless LAN, the AP for which the terminal carried out the association is called a connection AP, and at the moment that the terminal makes communication, it does so via this connection AP.

0025Deciding the connection APs at all observation points within the service area of the WLAN in such a manner allows the cell boundaries to be clarified as shown in <figref idref="f0007">Fig. 7</figref>, whereby the coverage range of each AP is partitioned by the cell boundary (step S15). The process of this step S15 is an operation of the cell range determining section 25 of <figref idref="f0003">Fig. 3</figref>.

0026Next, the method of clarifying the cell boundary by the actual measurement will be explained while making a reference to the flow of <figref idref="f0008">Fig. 8</figref>. The method by the actual measurement in this case utilizes a positioning function of the terminal. As an example of this positioning function, there are a method of finding the position from the power received from a plurality of the APs, a method of employing a system other than the WLAN, e.g. a GPS (Global Positioning System), etc. Or, a method that a measurer confirms a position on a map to inputs it is also acceptable.

0027A reference to <figref idref="f0008">Fig. 8</figref> is made, in which at first, the managing server 1 acquires from each of the terminals 5a to 5g its position information and identification information of the connection AP (information for specifying the above AP) (step S16), and provides them to the cell boundary computing server 2. The identification information of the connection AP at each position may be provided to the cell boundary computing server 2 via the network, and the collected information may be directly input into the cell boundary computing server 2. The cell boundary computing server 2 sums up the provided information and decides the cell boundary within the service area of the wireless LAN (step S17). With regard to this decision of the cell boundary, as shown in <figref idref="f0009">Fig. 9</figref>, collecting the identification information of the connection APs at a number of the observation points makes it possible to detect a spot (which becomes a cell boundary) in which the connection AP is changed.

0028In a case where it is difficult to decide a clear cell boundary because the measured information is little, with regard to the observation points in which the observation was not made yet, a computation is made, on the premise that a connection is made to an AP identical to the AP terminal at the nearest observation point out of the observation points at which the measurement was already made. Also, the technique of the simulation and the technique of the actual measurement described above can be combined to modifying the cell boundary decided by the technique of the simulation to the actual measurement result. For example, at first the cell boundary is temporarily decided with the foregoing simulation, and in a case where a discrepancy with data by the actual measurement (information of the terminal position and the connection AP) exists, the part that differs is modified into the cell boundary to be decided by the actual measurement, thereby, making it also possible to decide the final cell boundary. Doing so allows an accuracy of the cell boundary to be enhanced.

0029Next, the managing server 1 is for collecting/working the operational information from the wireless LAN appliance at each cell that is a coverage range of each AP found by the cell boundary computing server 2 (the step S2 of <figref idref="f0004">Fig. 4</figref>), and for numerically finding the operational situation cell by cell, and the details of the process in this case are shown in a flow of <figref idref="f0010">Fig. 10</figref>. That is, the operational information necessary for displaying the operational situation is collected from each wireless LAN appliance (step S21), and this collected operational information is worked responding to a necessity by employing a predetermined equation (step S22), thereby to display the operation status for each cell as a numerical value.

0030<figref idref="f0011">Fig. 11</figref> and <figref idref="f0012">Fig. 12</figref> illustrate a correspondence relation between a class of the operational situation that should be displayed on the displaying apparatus 3, and the operational information (acquired information) necessary for it, a correspondence relation with a source (the AP or the terminal) for acquiring the above information, and further a correspondence relation with a working/computing method of the operational information. An average received power is exemplified as the operational situation, in which the acquired information in this case is received power (desired-wave power) of the connection AP in each terminal, its working/computing method is given as (a total of received desired-wave power of the WLAN terminal within the cell) ÷ (the number of the WLAN terminal within the cell), and this computation result becomes a value of the average power received in the cell.

0031The operational situation such as the average received power value for each cell obtained in such a manner, which is delivered to the displaying apparatus 3, is displayed on a service area map of the wireless LAN (the step S3 of <figref idref="f0004">Fig. 4</figref>). That is, different colors or different patterns are allocated for displaying to each area (cell that is a coverage range of each AP) partitioned by the cell boundary clarified by the cell boundary determining process in the foregoing step S1 responding to the numerical value of the operational situation of the wireless LAN appliance that is positioned in each area, as shown in <figref idref="f0013">Fig. 13</figref>.

0032In a case where the operational situation is in a load status (see <figref idref="f0012">Fig. 12</figref>), making a gradation display such that the operational situation is displayed in white when the value of the load is small, and is displayed in gray to black as the value is increased enables the display of the operational situation associated with the detailed loads.

0033An average SN ratio (second one of <figref idref="f0011">Fig. 11</figref>) is taken into consideration as an example of the operational situation, in which collecting power (received desired-wave power) received from the connection AP from each terminal to calculate (a total of received desired-wave power of the WLAN terminal within the cell) ÷ (the number of the WLAN terminal within the cell) ÷ (noise power) allows the average SN ratio to be obtained. The displaying apparatus makes a gradation display, a color display, or a pattern display responding to this average SN ratio cell by cell.

0034As the operational situation, an average interference amount, an average SI ratio, a load status, a throughput, a use wireless channel, etc. are listed in addition hereto, as shown in <figref idref="f0011">Fig. 11</figref> and <figref idref="f0012">Fig. 12</figref>. The acquired information and the working/computing method for displaying each of these operational situations are ones shown in <figref idref="f0011">Fig. 11</figref> and <figref idref="f0012">Fig. 12</figref>.

0035<figref idref="f0014">Fig. 14</figref> is a view in which the interference situation is displayed in the actual WLAN service area map so as to be able to grasp it, and a display was made on a floor layout of some building. In this example, light and shade of the color allows the interference situation to be grasped, so it can be estimated that the interference is much in the cell of the AP 4c and deterioration in performance occurred because the coverage range (cell) of the AP 4c was displayed in deep color. Also, for example, in a case where the user of the terminal within the cell of the AP 4c made a report of the deterioration in performance, after the position of the user was confirmed, collating its report with this display makes it possible to immediately determine that the deterioration in performance of the above terminal is due to interference because the deterioration due to interference is much in the cell in which its terminal exists.

0036In the conventional technique of <patcit id="pcit0005" dnum="JPP199893616A"><text>JP-P1998-93616A</text></patcit>, at first, the user of the above terminal is requested to confirm which AP is a connection AP, or the administrator himself/herself goes to the location in which the user is positioned, and confirms the connection AP. Thereupon, he/she confirms the interference situation of the connection AP, and determines that the deterioration in performance of the above terminal is due to an influence of the interference.

0037In such a manner, in the conventional technique, it takes labor and time to find the cause of the deterioration in performance; however in the present invention, as mentioned above, determining it momentarily is enabled. Also, as shown in <figref idref="f0014">Fig. 14</figref>, specifying the position for removing the interference source also becomes easy because an influence of the interference can be confirmed on the WLAN service area map. In such a manner, the present invention makes the process of the operation management such as a solution of obstacles quick and yet easy as compared with the conventional technique.

0038Additionally, in a case where the managing server 1 collects various kinds of operational information from each WLAN appliance, a management protocol such as a SNMP (Simple Network Management Protocol) is employed.

0039<figref idref="f0015">Fig. 15</figref> is a system block diagram illustrating another embodiment of the present invention, and identical codes are affixed to the part identical to <figref idref="f0001">Fig. 1</figref>. In a case of employing a WLAN switch 6 that specialized in the WLAN, this switch is one caused to have a function 61 of the managing server 1 shown in <figref idref="f0001">Fig. 1</figref> because this WLAN switch 6 has a management function of the AP. Doing so eliminates a necessity for making the managing server another hardware component, thus enabling the scale of the hardware to be reduced.

0040<figref idref="f0016">Fig. 16</figref> is a system block diagram illustrating yet another embodiment of the present invention, and identical codes are affixed to the part identical to <figref idref="f0001">Fig. 1</figref>. In this embodiment, a certain terminal (terminal 5g) out of the terminals 5a to 5g has the display function of the displaying apparatus 3 shown in <figref idref="f0001">Fig. 1</figref> provided, and in a case of a configuration in which the managing server 1 serves as not only a managing server but also a WEB server, adding a WEB browser to this terminal 5g enables the displays of <figref idref="f0013">Fig. 13</figref> and <figref idref="f0014">Fig. 14</figref>.

0041In a case where the user of this terminal 5g sensed deterioration in characteristics, for example, perusing the display of the interference situation with this display function enables the user to find the cell of which the interference situation is more excellent than that of the cell to which the user belongs to move to its cell, and the user himself/herself to improve the deterioration in characteristics.

0042In the embodiment and another embodiment explained above, with the display of the screen, a plurality of classes of the operational situations for each cell may be displayed, by changing one screen. Also, a plurality of classes of the operational situations for each cell may be simultaneously displayed on one screen. An example of a case of the latter is shown in <figref idref="f0017">Fig. 17</figref>. Herein, the status of the load for each cell and the status of the average SN ratio were displayed on one screen. With a case of the latter, it becomes possible to simultaneously check a plurality of deterioration factors in performance, thereby, for example, enabling the deterioration factors in performance to be quickly investigated for the claims etc. from the user. Further, as another example, the different numerical values of the operational situations may be displayed, based upon a value obtained by synthesizing them (for example, weighted addition of them respectively)

0043Needless to say, a configuration can be configured so that with each process flow in the above-mentioned embodiments, a process procedure thereof is pre-recorded in a record medium such as a ROM as a program to cause a computer (CPU) to read and execute it. In summary, an embodiment of the invention can be described as follows:

0044In a case of operating a wireless LAN system for covering a wide-range area employing a plurality of APs (Access Points), propriety of a coverage range of the AP is visually displayed together with its influence range on an area map with an operational situation based upon a load situation, an interference situation, a utilization situation of a channel, etc. reflected.

0045Various kinds of operational information of a wireless appliance in a cell of each of APs 4a to 4c is collected by a managing server 1, and also, a cell boundary of each AP is determined by a cell boundary server 2. And, the managing server 1 works/computes the collected operational information, and finds the operational situation in each cell. And, a displaying apparatus 3 partitions a service area of the wireless LAN system with a cell boundary, and makes a display so that a display aspect thereof differs responding to the operational situation for each cell found in the managing server 1. This allows the display aspect that coincided with the operational situation to be obtained, thereby making it possible to display propriety of the operational situation for each cell coverage range by coverage range of the AP.