JP4886647B2 - Frequency channel selection device, frequency channel selection method, and computer program - Google Patents

Description

  The present invention relates to a frequency channel selection device, a frequency channel selection method, and a computer program in a wireless communication system having a plurality of frequency channels.

In recent years, the spread of wireless local area network (wireless LAN) systems has progressed, and a large number of base stations (access points, APs) have been installed, resulting in frequency interference between cells formed by each AP. There is a concern that the communication performance deteriorates. In order to avoid or reduce interference between cells, it is important to use an appropriate frequency channel in each AP. In order to pre-design an appropriate frequency channel, it is necessary to accurately estimate the cell state. As a conventional technique, for example, Patent Document 1 discloses a base station control technique based on a regular arrangement of cells.
JP 2005-27189 A

  However, in the wireless LAN system, the cell communication area radius is generally as narrow as several tens of meters, and the structure in the communication area (the shape and arrangement of a building or the like if outdoor, the structure of a room if indoor) Cell size and cell shape change, and the cell arrangement becomes irregular. Furthermore, it is difficult to obtain information on APs of other wireless LAN systems that do not belong to the own wireless LAN system, and it is often impossible to estimate the cell arrangement. For this reason, it is difficult to apply in the base station control technology based on the regular arrangement of cells as disclosed in Patent Document 1.

  Furthermore, “IEEE802.11b / g / n”, which is defined by the Institute of Electrical and Electronic Engineers (IEEE) as a 2.4 GHz band wireless LAN system, has a plurality of frequency channels (hereinafter simply referred to as channels). However, as shown in FIG. 6, the frequencies overlap between the channels. In the example of FIG. 6, 14 channels Ch1 to Ch14 are provided. If the channel spacing is not five or more, inter-channel interference occurs. Therefore, in order to prevent interchannel interference, it is necessary to use channels in combinations such as (Ch1, Ch6, Ch11) and (Ch2, Ch7, Ch12). For this reason, it is not necessarily possible to simply use different channels in each AP, and it is an issue to use a combination of channels appropriately.

  The present invention has been made in consideration of such circumstances, and the object thereof is to be used by a base station in a wireless communication system in which frequencies overlap between channels, such as a 2.4 GHz band wireless LAN system. An object of the present invention is to provide a frequency channel selection device, a frequency channel selection method, and a computer program capable of appropriately selecting a combination of channels.

  In order to solve the above-described problem, a frequency channel selection device according to the present invention is a frequency channel selection device in a radio communication system having a plurality of frequency channels. Measurement data extraction means for deleting the measurement data related to the base station of the own system from the measurement data and extracting the measurement data related to the base station of another wireless communication system, and the received signal strength included in the extracted measurement data Based on the index value calculating means for calculating the index value representing the received signal strength of the interference signal of each frequency channel, weighted addition of the index value of each frequency channel based on a predetermined inter-channel interference table, Interference degree calculating means for calculating the interference degree of the channel, and frequency overlap based on the interference degree of each frequency channel From the predetermined channel combination consists of no frequency channel, a channel combination selection means for the influence of interference is to select a channel combination is a minimum, characterized by comprising a.

  In the frequency channel selection apparatus according to the present invention, the inter-channel interference table is composed of weighting factors representing the degree of interference between the frequency channels.

  In the frequency channel selection apparatus according to the present invention, the index value is a sum of received signal strengths for each frequency channel.

  In the frequency channel selection apparatus according to the present invention, the index value is a maximum value of received signal strength for each frequency channel.

  In the frequency channel selection apparatus according to the present invention, the channel combination selection means calculates a sum of interference degrees of each frequency channel for each of the predetermined channel combinations, and selects a channel combination having the minimum sum of interference degrees. It is characterized by that.

  In the frequency channel selection device according to the present invention, the channel combination selection unit obtains the maximum value of the interference degree of the frequency channel for each of the predetermined channel combinations, and selects the channel combination having the minimum value of the interference degree. It is characterized by that.

  The frequency channel selection method according to the present invention is a frequency channel selection method in a radio communication system having a plurality of frequency channels, and the measurement data extraction means measures the received signal strength of radio waves in the use frequency band of the radio communication system. Deleting the measurement data related to the base station of the own system from the data, extracting the measurement data related to the base station of another wireless communication system, and receiving the index value calculating means included in the extracted measurement data Calculating an index value representing the received signal strength of the interference signal of each frequency channel based on the signal strength, and an interference degree calculating means weights the index value of each frequency channel based on a predetermined inter-channel interference table Adding, calculating a degree of interference of each frequency channel, and a channel combination selection means comprising: Based on the degree of coherence, characterized in that it comprises from a predetermined channel combination consists of a frequency channel there is no overlap of frequencies, the steps of the influence of interference is to select a channel combination is a minimum, the.

A computer program according to the present invention is a computer program for performing frequency channel selection processing in a radio communication system having a plurality of frequency channels, and is based on measurement data of received signal strength of radio waves in a use frequency band of the radio communication system. Based on the measurement data extraction function that deletes the measurement data related to the base station of its own system and extracts the measurement data related to the base station of another wireless communication system, and the received signal strength included in the extracted measurement data An index value calculation function for calculating an index value representing the received signal strength of the interference signal of each frequency channel, and weighted addition of the index value of each frequency channel based on a predetermined inter-channel interference table, and interference of each frequency channel Based on the interference degree calculation function for calculating the degree of interference and the interference degree of each frequency channel, It is characterized in that to realize from a predetermined channel combination consists of no frequency channel, a channel combination selection function effects of interference selects a channel combination is the smallest, to the computer.
As a result, the frequency channel selection apparatus described above can be realized using a computer.

  According to the present invention, in a wireless communication system in which frequencies overlap between channels, for example, in a 2.4 GHz band wireless LAN system, it is possible to appropriately select a combination of channels used by a base station. It is done.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a frequency channel selection apparatus 1 according to an embodiment of the present invention.

  The frequency channel selection apparatus 1 according to the present embodiment selects a combination of channels used by an AP for a 2.4 GHz band wireless LAN system. The operator of the wireless LAN system can use the frequency channel selection device 1 when determining the channel combination used by the AP of the own wireless LAN system.

  In this embodiment, it is assumed that the channels that can be used by the 2.4 GHz band wireless LAN system are 14 channels Ch1 to 14 whose frequencies are overlapped between channels as shown in FIG. If the channel spacing is not 5 or more, inter-channel interference occurs.

  In FIG. 1, the frequency channel selection device 1 includes an other system AP extraction unit 11, an own system AP list storage unit 12, an RSSI sum calculation unit 13, an interference degree calculation unit 14, an interchannel interference table storage unit 15, and a channel combination selection unit. 16 and a channel combination storage unit 17. Hereinafter, description will be given with reference to FIG. FIG. 5 is a processing flowchart showing the procedure of the frequency channel selection method according to the present embodiment.

  A measurement result list is input to the frequency channel selection device 1. The measurement result list measures 2.4 GHz band radio waves in the communication service area of the own wireless LAN system and records the measurement results in a list format. FIG. 2 shows a configuration example of the measurement result list. As shown in FIG. 2, the measurement result list includes a position where the radio wave is measured (point number corresponding to the measurement position), AP identification information (MAC address etc.) identifying the AP that is the source of the received radio wave, The received signal strength indicator (RSSI) of the received radio wave and the channel number of the received channel are recorded as a set.

  The other system AP extraction unit 11 extracts AP data of another system that does not belong to the own wireless LAN system from the input measurement result list. In the own system AP list storage unit 12, AP identification information of APs belonging to the own wireless LAN system is recorded in advance as a preparation stage. The other system AP extraction unit 11 deletes the data of the set of AP identification information recorded in the own system AP list storage unit 12 from the measurement result list. As a result, only AP data of other systems not belonging to the own wireless LAN system remains in the measurement result list. As a result, as shown in FIG. 5, the data of the AP of the own system is deleted from the measurement result list, and the measurement result list of only the APs of other systems is created.

  The RSSI sum calculation unit 13 calculates the sum of RSSI for each channel for a measurement result list including only AP data of other systems. At this time, if the unit of RSSI is recorded in decibels (dB), the decibel value is converted to a true value and then RSSI is summed. FIG. 3 shows a configuration example of the RSSI sum calculation result. As shown in FIG. 3, the RSSI sum calculation unit 13 records the RSSI sum in a list format for each channel. As a result, as shown in FIG. 5, the RSSI sum of each channel is calculated from the measurement result list of only APs of other systems.

  The interference level calculation unit 14 calculates the interference level of each channel from the RSSI sum of each channel. For the calculation of the interference degree of each channel, an inter-channel interference table recorded in the inter-channel interference table storage unit 15 is used.

  FIG. 4 shows a configuration example of the interchannel interference table. As shown in FIG. 4, the inter-channel interference table is a matrix corresponding to the number of channels. In this embodiment, it is a matrix of 14 rows and 14 columns corresponding to 14 channels Ch1 to Ch14. The inter-channel interference table is composed of weighting factors representing the degree of interference between the channels. As the weighting factor, for example, the degree of frequency overlap between channels, the deterioration rate indicating how much the communication speed (throughput) in the wireless LAN terminal deteriorates between channels, and the like, for each combination of channels, 0 to 1 Digitize in range. 0 represents no interference and 1 definitely represents interference. This numerical value is recorded in a matrix format to obtain an interchannel interference table. The interchannel interference table storage unit 15 records an interchannel interference table in advance as a preparation stage.

  The interference degree calculation unit 14 treats the RSSI sum of each channel obtained from the measurement result list of only APs of other systems as an index value representing the RSSI of the interference signal of each channel. Then, the interference degree calculation unit 14 calculates a matrix product of the inter-channel interference table and the RSSI sum of each channel by matrix calculation as shown in FIG. As shown in FIG. 5, the matrix product of the interchannel interference table (14 × 14 matrix) and the RSSI sum (14 × 1 matrix) of each channel is calculated. In this matrix calculation, the RSSI index value of the interference signal of each channel is weighted and added by the value (weighting coefficient) for each channel combination in the interchannel interference table. The matrix product of the matrix calculation result is a matrix (14 rows and 1 column) composed of the interference degree of each channel. Thereby, the interference degree of each channel is obtained.

  The channel combination selection unit 16 selects a channel combination having the minimum influence of interference from predetermined channel combinations based on the interference level of each channel. Each channel combination is composed of channels with no frequency overlap.

  The channel combination storage unit 17 stores available channel combinations. In this embodiment, 14 channels Ch1 to 14 can be used, but interchannel interference occurs if the channel spacing is not 5 or more apart. For this reason, a combination of channels whose channel intervals are five or more apart is set as an available channel combination. For example, (Ch1, Ch6, Ch11), (Ch2, Ch7, Ch12), (Ch3, Ch8, Ch13), and (Ch4, Ch9, Ch14) are recorded in the channel combination storage unit 17 as available channel combinations.

  For each channel combination recorded in the channel combination storage unit 17, the channel combination selection unit 16 calculates the sum of the interference degrees of the channels included in the channel combination. Thereby, the sum of the interference degrees is obtained for each channel combination. The channel combination selection unit 16 selects a channel combination having a minimum sum of interference degrees from the channel combinations recorded in the channel combination storage unit 17. The channel combination selection unit 16 outputs information on the selected channel combination. This selected channel combination is a combination of channels with no frequency overlap, and the combination having the least influence of interference from other systems.

  Thereby, the operator selects an appropriate channel combination by using the channel combination information output from the frequency channel selection device 1 when determining the channel combination used by the AP of the own wireless LAN system. Will be able to.

  In the above-described embodiment, the RSSI sum calculation unit 13 calculates the RSSI sum for each channel for the measurement result list consisting only of AP data of other systems, and uses this as the received signal of the interference signal of each channel. Although the index value representing the strength is used, the maximum RSSI value may be obtained instead of the sum of RSSI, and this may be used as the index value representing the received signal strength of the interference signal of each channel. In this case, the interference degree calculation unit 14 calculates a matrix product of the interchannel interference table and the RSSI maximum value of each channel.

  In the above-described embodiment, the channel combination selection unit 16 calculates the sum of the interference degrees of the channels included in the channel combination for each channel combination recorded in the channel combination storage unit 17. Alternatively, the maximum value of the channel interference may be obtained. In this case, the channel combination selection unit 16 selects a channel combination having the minimum interference degree from the channel combinations recorded in the channel combination storage unit 17.

  The frequency channel selection apparatus 1 according to the present embodiment may be realized by dedicated hardware, or may be configured by a computer system such as a personal computer, and the frequency channel selection apparatus 1 shown in FIG. The function may be realized by executing a program for realizing the function of each unit.

In addition, it is assumed that an input device, an output device, and the like (none of which are shown) are connected to the frequency channel selection device 1 as peripheral devices. Here, the input device refers to an input device such as a keyboard and a mouse, a reading device that reads data from a recording medium, and the like. Examples of the output device include a display device such as a CRT (Cathode Ray Tube) and a liquid crystal display device, a recording device for a recording medium, and a printing device.
The peripheral device may be directly connected to the frequency channel selection device 1 or may be connected via a communication line.

Further, a program for realizing the function of the frequency channel selection device 1 shown in FIG. 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. The frequency channel selection process may be performed. Here, the “computer system” may include an OS and hardware such as peripheral devices.
Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
“Computer-readable recording medium” refers to a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disk), and a built-in computer system. A storage device such as a hard disk.

Further, the “computer-readable recording medium” means a volatile memory (for example, DRAM (Dynamic DRAM) in a computer system that becomes a server or a client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line. Random Access Memory)), etc., which hold programs for a certain period of time.
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
For example, in the above-described embodiment, the 2.4 GHz band wireless LAN system is taken as an example, but the present invention can be applied to various wireless communication systems in which there is a frequency overlap between available channels.

It is a block diagram which shows the structure of the frequency channel selection apparatus 1 which concerns on one Embodiment of this invention. It is an example of composition of a measurement result list concerning the embodiment. It is an example of a structure of the calculation result of the sum of RSSI concerning the embodiment. It is an example of a structure of the inter-channel interference table which concerns on the same embodiment. It is a processing flow figure showing a procedure of a frequency channel selection method concerning the embodiment. It is explanatory drawing for demonstrating the channel which can use a 2.4 GHz band wireless LAN system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Frequency channel selection apparatus, 11 ... Other system AP extraction part (measurement data extraction means), 12 ... Own system AP list storage part, 13 ... RSSI sum calculation part (index value calculation means), 14 ... Interference degree calculation part, 15 ... Interchannel interference table storage unit, 16 ... Channel combination selection unit, 17 ... Channel combination storage unit

Claims (8)

In a frequency channel selection apparatus in a radio communication system having a plurality of frequency channels,
Measurement data extraction for deleting measurement data related to the base station of the own system and extracting measurement data related to the base station of another wireless communication system from the measurement data of the received signal strength of the radio wave in the use frequency band of the wireless communication system Means,
Index value calculating means for calculating an index value representing the received signal strength of the interference signal of each frequency channel based on the received signal strength included in the extracted measurement data;
An interference degree calculating means for performing weighted addition of the index values of each frequency channel based on a predetermined inter-channel interference table and calculating an interference degree of each frequency channel;
Channel combination selection means for selecting a channel combination having the smallest influence of interference from predetermined channel combinations configured of frequency channels having no frequency overlap based on the interference degree of each frequency channel;
A frequency channel selection apparatus comprising:   2. The frequency channel selection apparatus according to claim 1, wherein the inter-channel interference table is composed of weighting factors representing the degree of interference between frequency channels.   The frequency channel selection apparatus according to claim 1, wherein the index value is a sum of received signal strengths for each frequency channel.   The frequency channel selection apparatus according to claim 1, wherein the index value is a maximum value of received signal strength for each frequency channel.   2. The channel combination selecting unit according to claim 1, wherein the channel combination selection unit calculates a sum of interference degrees of each frequency channel for each of the predetermined channel combinations, and selects a channel combination having the minimum interference degree. Frequency channel selection device.   2. The channel combination selection unit obtains a maximum value of the interference degree of the frequency channel for each of the predetermined channel combinations, and selects a channel combination having the minimum interference degree as a minimum. Frequency channel selection device. A frequency channel selection method in a wireless communication system having a plurality of frequency channels, comprising:
The measurement data extracting means deletes the measurement data related to the base station of the own system from the measurement data of the received signal strength of the radio wave in the use frequency band of the wireless communication system, and the measurement data related to the base station of another wireless communication system Extracting the
An index value calculating means calculating an index value representing the received signal strength of the interference signal of each frequency channel based on the received signal strength included in the extracted measurement data;
An interference degree calculating means weighting and adding the index value of each frequency channel based on a predetermined inter-channel interference table, and calculating an interference degree of each frequency channel;
Channel combination selection means, based on the degree of interference of each frequency channel, selecting a channel combination that is least affected by interference from predetermined channel combinations that are configured from frequency channels that do not overlap in frequency; ,
A frequency channel selection method comprising: A computer program for performing frequency channel selection processing in a wireless communication system having a plurality of frequency channels,
Measurement data extraction for deleting measurement data related to the base station of the own system and extracting measurement data related to the base station of another wireless communication system from the measurement data of the received signal strength of the radio wave in the use frequency band of the wireless communication system Function and
An index value calculating function for calculating an index value representing the received signal strength of the interference signal of each frequency channel based on the received signal strength included in the extracted measurement data;
An interference degree calculation function for calculating the interference degree of each frequency channel by weighting and adding the index values of each frequency channel based on a predetermined inter-channel interference table;
A channel combination selection function for selecting a channel combination having a minimum influence of interference from predetermined channel combinations configured of frequency channels having no frequency overlap based on the interference degree of each frequency channel;
A computer program for causing a computer to realize the above.

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