JP2005142811A - System and method for base station selection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize efficient communication even when the communication is newly started and to decentralize the load on the whole communication network. <P>SOLUTION: A wireless terminal station 10 receives beacon signals from all wireless base stations 20A, 20B, 20C, and 20D included in a subnetwork, and calculates mean received electric power based upon the beacon signals to extract information on the number of connections, The wireless terminal station 10 specifies all wireless base stations which have mean received electric power equal to or above a prescribed value among the wireless base stations 29A, 20B, 20C, and 20D. Then the wireless terminal station 10 selects and connects the wireless base station having the least number of connections of wireless terminal stations among the specified wireless base stations on the basis of the information on the number of connection. When there is not a wireless base station having mean received electric power equal to or above the prescribed value, the wireless terminal station 10 selects and connects the wireless base station which has the largest mean received electric power. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a base station selection system and a base station selection method in which a wireless terminal station selects a connection-destination wireless base station in a communication network including a plurality of wireless base stations, and more particularly to a wireless terminal station in a wireless LAN. The present invention relates to a base station selection system and a base station selection method for selecting a station.

  When communication is started via a wireless LAN, a terminal station such as a personal computer must first select and connect to a connection-destination wireless base station. As a method of selecting a connection-destination radio base station, an ESS-ID (Extended Service Set Identity) of the connection-destination radio base station is set in advance, and the terminal station connects to the radio base station based on the set ESS-ID. There is a way to do it. There is also a method in which a terminal station connects to a radio base station based on an ESS-ID input in accordance with a user operation.

  However, when connecting based on a preset ESS-ID or an ESS-ID input by a user, connections from a plurality of terminal stations are concentrated on one wireless base station, and the entire wireless LAN subnetwork is connected. Efficient communication may not be possible. In addition, when the arrangement of terminal stations in the sub-network changes or the number of terminal stations changes, if the connection is made based on a preset ESS-ID, the terminal station always has to change unless the terminal station changes the set ESS-ID. In some cases, the same wireless base station is connected, and efficient communication cannot be performed in the entire subnetwork.

  As a method for performing efficient communication, Patent Literature 1 describes a base station attribution switching method that can reduce the load by distributing the access concentration of mobile terminal stations to a radio base station. In the base station belonging switching method described in Patent Document 1, a mobile terminal station always receives a beacon signal from another radio base station when belonging to any one of the radio base stations. Then, the mobile terminal station determines whether to switch the connection destination to another radio base station based on the received power of the beacon signal and the information on the number of connected terminals included in the beacon signal.

JP 2002-359864 A (page 4-5, FIG. 4)

  According to the base station attribution switching method described in Patent Document 1, when a communication is performed while connected to any of the radio base stations, the access load on the radio base station is concentrated on the terminal station. Since the connection is automatically switched to another radio base station after determination, the access concentration to the radio base station can be distributed and the load can be reduced. However, since the concentration of access is already determined after connecting to any one of the radio base stations, the terminal station cannot select and connect to a radio base station with a small load at the start of communication. Therefore, when a plurality of terminal stations are simultaneously connected to one radio base station at the time of starting communication, access to the radio base station is concentrated and efficient communication may not be performed.

  Further, in the base station attribution switching method described in Patent Document 1, since only the access concentration for each radio base station is distributed, the load on the entire subnetwork is not necessarily distributed and efficient communication can be performed. Is not limited.

  Therefore, the present invention provides a base station selection system and a base station selection method capable of performing efficient communication even when newly starting communication and distributing the load of the entire communication network. The purpose is to do.

  A base station selection system according to the present invention is a base station selection system in which a radio terminal station selects an associated radio base station from a plurality of radio base stations in a communication network including a plurality of radio base stations. Comprises a signal transmission means for transmitting a radio signal including connection number information indicating the number of radio terminal stations connected to the radio base station. When the radio terminal station belongs to the radio base station, Based on signal reception means for receiving radio signals from all included radio base stations, received power of received radio signals, and connection number information included in the radio signals, all radio base stations included in the communication network Base station selection means for selecting one of the radio base stations is provided.

  The wireless terminal station includes connection number information extraction means for extracting connection number information from the received wireless signal, received power calculation means for calculating received power of the received wireless signal, and all of the wireless base stations included in the communication network. Among them, a base station specifying unit that specifies all radio base stations whose calculated received power is greater than a predetermined value, and the base station selecting unit is based on the connection number information extracted by the connection number information extracting unit, Of the radio base stations identified by the base station identification means, a radio base station with the smallest number of connected radio terminal stations may be selected. According to such a configuration, it is possible to select a radio base station that can perform the most efficient communication after specifying in advance a radio base station that can ensure predetermined communication quality. Therefore, efficient communication can be performed even when a new communication is started while ensuring a predetermined communication quality, and the load of the entire communication network can be distributed.

  When there is no radio base station whose reception power is greater than a predetermined value, the base station selection means selects a radio base station corresponding to the largest reception power among all the radio base stations included in the communication network. You may do. According to such a configuration, even when there is no radio base station that can ensure predetermined communication quality, the radio terminal station can select and connect the radio base station with the best communication quality.

  The signal receiving unit receives a radio signal for a predetermined time for each radio base station, and the received power calculating unit calculates an average received power that is an average value of the received power of the radio signal received during the predetermined time. The base station specifying means may specify all the radio base stations whose average received power is greater than a predetermined value among all the radio base stations included in the communication network. According to such a configuration, it is possible to select a radio base station that can perform the most efficient communication after specifying in advance a radio base station that can ensure predetermined communication quality. Moreover, since communication quality is judged based on the average value of received power, stable communication quality can be ensured. Therefore, it is possible to perform efficient communication even when newly starting communication while ensuring stable communication quality, and to distribute the load of the entire communication network.

  The connection number information extracting means may extract connection number information from the last received radio signal among radio signals received during a predetermined period. According to such a configuration, it is possible to select a radio base station that can perform efficient communication based on information on the number of latest radio terminal stations connected to each radio base station.

  When there is no radio base station whose average received power is greater than a predetermined value, the base station selecting means is a radio base station corresponding to the largest average received power among all the radio base stations included in the communication network. May be selected. According to such a configuration, even when there is no radio base station that can ensure predetermined communication quality, the radio terminal station can select and connect the radio base station with the best communication quality. In addition, since the communication quality is determined based on the average value of the received power, the radio base station having the most stable communication quality can be selected.

  The signal transmission means transmits radio signals of different frequencies for each radio base station, and the radio terminal station has registration means for pre-registering the frequencies of radio signals transmitted by all radio base stations included in the communication network. The signal receiving means may be configured to receive radio signals from all radio base stations included in the communication network based on each frequency registered by the registration means. According to such a configuration, it is possible to easily collect information on the reception power of all radio base stations and the number of connections of radio terminal stations included in the communication network.

  Base station connection means for connecting to the radio base station selected by the base station selection means may be provided. According to such a configuration, it is possible to automatically connect to a radio base station that can perform the most efficient communication.

  The signal transmission means may transmit a beacon signal including connection number information as a radio signal. According to such a configuration, the wireless terminal station can perform efficient communication by receiving a beacon signal from each wireless base station.

A base station selection method according to the present invention is a base station selection method in which a radio terminal station selects an associated radio base station from a plurality of radio base stations in a communication network including a plurality of radio base stations, Transmitting a radio signal including connection number information indicating the number of radio terminal stations connected to the radio base station, and when the radio terminal station belongs to the radio base station, all included in the communication network Receiving the radio signal from the radio base station, and the radio terminal station, based on the received power of the received radio signal and the number of connections information included in the radio signal, of all the radio base stations included in the communication network Selecting one of the radio base stations.

  The base station selection method includes a step in which the wireless terminal station extracts connection number information from the received wireless signal, a step in which the wireless terminal station calculates received power of the received wireless signal, The step of identifying all the radio base stations whose calculated received power is greater than a predetermined value out of all the radio base stations included in the communication network, and the radio terminal station is identified based on the extracted connection number information And a step of selecting a radio base station having the smallest number of connected radio terminal stations among the radio base stations. According to such a configuration, it is possible to select a radio base station that can perform the most efficient communication after specifying in advance a radio base station that can ensure predetermined communication quality. Therefore, efficient communication can be performed even when a new communication is started while ensuring a predetermined communication quality, and the load of the entire communication network can be distributed.

  According to the present invention, when belonging to a radio base station, the received power of each radio base station and the number of connections of the radio terminal station are determined. Therefore, even when a new communication is started, the radio terminal station It is possible to automatically select a radio base station capable of efficient communication. Further, since information on the received power and the number of connected wireless terminal stations is collected for all wireless base stations included in the communication network, a wireless base station with a small load can be selected from all the wireless base stations, and the communication network The entire load can be distributed. Therefore, efficient communication can be performed even when communication is newly started, and the load on the entire communication network can be distributed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of the configuration of a base station selection system according to the present invention. In the present embodiment, a case will be described in which the base station selection system is applied to a wireless LAN IP network range generally called a subnetwork.

  As shown in FIG. 1, the subnetwork includes four radio base stations 20A, 20B, 20C, and 20D, and a plurality of radio terminal stations 10. In the sub-network, the radio base stations 20A, 20B, 20C, and 20D are connected to a wired network 30 such as Ethernet (registered trademark). Note that the number of radio base stations 20A, 20B, 20C, and 20D is not limited to four, and, for example, five or more radio base stations may be included in one subnetwork.

  The wireless LAN in this embodiment is a multiple access network using a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) system standardized by IEEE802.11. The wireless terminal station 10 selects and connects any one of the plurality of wireless base stations 20A, 20B, 20C, and 20D included in the subnetwork. The radio terminal station 10 can select and connect any radio base station as long as it is the radio base stations 20A, 20B, 20C, and 20D included in the sub-network.

  In the present embodiment, the sub-network is a network generally called BSS (Basic Service Set) in which each of the radio base stations 20A, 20B, 20C, and 20D performs radio communication with the radio terminal station 10 using different frequencies. Consists of units.

  In this embodiment, the case where the radio base stations 20A, 20B, 20C, 20D and the radio terminal station 10 perform radio communication using radio wave signals will be described. For example, radio communication using infrared signals or the like is performed. You may do it.

  FIG. 2 is a block diagram illustrating an example of the configuration of the wireless terminal station 10. As shown in FIG. 2, the wireless terminal station 10 includes a wireless LAN module 40 for connecting to a wireless LAN and a PC 50 that is a terminal used by a user.

  The PC 50 is an information processing terminal such as a personal computer or a workstation. The PC 50 also includes an interface unit (not shown) including a PCMCIA (Personal Computer Memory Card International Association) card and a PCI (Peripheral Component Interconnect) bus for connecting to the wireless LAN module 40.

  As shown in FIG. 2, the wireless LAN module 40 includes a PC interface unit 41 for connecting to the PC 50, a MAC unit 42 for controlling access, a modem unit 43 for modulating / demodulating, an RF unit 44 for transmitting / receiving wireless data, and each A CPU 45 that executes processing according to a program is included.

  The PC interface unit 41 performs packet transmission / reception with the PC 50. The MAC unit 42 performs media access control (MAC) according to various protocols defined for the wireless LAN. The modem unit 43 modulates data transmitted to the radio base stations 20A, 20B, 20C, and 20D and demodulates data received from the radio base stations 20A, 20B, 20C, and 20D.

  The RF unit 44 includes an antenna (not shown) and a high-frequency circuit unit (not shown). The RF unit 44 converts the baseband modulation signal from the modem unit 43 into a radio signal of radio frequency (RF) and transmits the radio signal to the radio base stations 20A, 20B, 20C, and 20D. The RF unit 44 converts the radio signal received from the radio base stations 20A, 20B, 20C, and 20D into a baseband modulation signal and outputs the baseband modulation signal to the modem unit 43. For example, the RF unit 44 receives a beacon signal as a radio signal from the radio base stations 20A, 20B, 20C, and 20D, as will be described later.

  The CPU 45 controls each block included in the wireless LAN module 40 such as the PC interface unit 41, the MAC unit 42, the modem unit 43, and the RF unit 44 according to each program stored in a memory (not shown) of the wireless LAN module 40. .

  FIG. 3 is a block diagram illustrating an example of the configuration of the radio base stations 20A, 20B, 20C, and 20D. As shown in FIG. 3, the wireless base stations 20A, 20B, 20C, and 20D include a wireless LAN module 60 for wireless connection with the wireless terminal station 10, and a CPU board 70 that performs each communication process with the wireless terminal station 10. including.

  The CPU board 70 includes an interface unit (not shown) for connecting to the wired network 30 and a CPU (not shown). The CPU board 70 transfers the packet from the wireless LAN module 60 to another terminal or the like via the wired network 30. Further, the CPU board 70 transfers a packet received via the wired network 30 to the wireless LAN module 60. Further, the CPU board 70 performs connection processing with the wireless terminal station 10 and the like.

  As shown in FIG. 3, the wireless LAN module 60 includes a PC interface unit 61, a MAC unit 62, a modem unit 63, an RF unit 64, and a CPU 65. The functions and configurations of the PC interface unit 61, MAC unit 62, modem unit 63, RF unit 64, and CPU 65 are the same as those of the PC interface unit 41, MAC unit 42, modem unit 43, RF unit 44, and CPU 45.

  Further, the MAC unit 42 of the wireless terminal station 10 and the MAC units 62 of the wireless base stations 20A, 20B, 20C, and 20D include a beacon control unit for processing beacon signals. FIG. 4 is a block diagram illustrating an example of the configuration of the beacon control unit included in the MAC units 42 and 62. As shown in FIG. 4, the beacon control unit includes a beacon identifying unit 81 for identifying a beacon and a beacon processing unit 82 for processing a beacon signal.

  The functions and configurations of the beacon control units on the wireless terminal station side and the wireless base station side are the same, but when used for the wireless terminal station and when used for the wireless base station, the following Behave differently. Note that the beacon control units for the wireless terminal station and the wireless base station may have different functions and configurations depending on the difference in operation.

  In the beacon control unit included in the MAC unit 42 of the wireless terminal station 10, the beacon identifying unit 81 identifies whether or not the received packet from the modem unit 43 is a beacon signal. Further, when the beacon identifying unit 81 determines that the received packet is a beacon signal, the beacon identifying unit 81 outputs the received packet to the beacon processing unit 82.

  In the beacon control unit included in the MAC unit 42 of the wireless terminal station 10, the beacon processing unit 82 performs frame analysis of the beacon signal from the modem unit 43 and extracts information included in the beacon signal. Further, the beacon processing unit 82 outputs the extracted information to each module in the wireless LAN module 40 such as the CPU 45. The beacon processing unit 82 includes a register 83 that temporarily stores information to be output to the CPU 45 among the extracted information.

  In the beacon control unit included in the MAC unit 62 of the radio base stations 20A, 20B, 20C, and 20D, the beacon processing unit 82 collects information from each module in the wireless LAN module 60 such as the CPU 65, and collects each information A beacon frame (beacon signal) including is generated. Hereinafter, each piece of information included in the beacon signal generated by the beacon processing unit 82 is simply referred to as beacon information. In the beacon control unit included in the MAC unit 62 of the radio base stations 20A, 20B, 20C, and 20D, the beacon identifying unit 81 outputs the beacon frame generated by the beacon processing unit 82 to the modem unit 63.

  The beacon processing unit 82 on the radio base stations 20A, 20B, 20C, and 20D side detects the number of radio terminal stations currently connected to the radio base station that is the current station when generating a beacon frame. . And the beacon process part 82 produces | generates the beacon signal which contains the information of the number of connection of a wireless terminal station as beacon information. Hereinafter, the information on the number of connections of wireless terminal stations included in the beacon signal is simply referred to as connection number information.

  The signal transmission unit is realized by the RF unit 64, the CPU 65, and the like. The signal receiving means and the base station connection means are realized by the RF unit 44, the CPU 45, and the like. The base station selecting means and the base station specifying means are realized by the CPU 45 or the like. The connection number information extracting unit and the received power calculating unit are realized by the beacon processing unit 82, the CPU 45, and the like. The setting means is realized by the memory of the wireless LAN module 40, the CPU 45, and the like.

  Next, the operation will be described. FIG. 5 is a flowchart illustrating an example of a radio base station selection process when the radio terminal station 10 requests connection to the radio base stations 20A, 20B, 20C, and 20D at the start of communication. In the present embodiment, each of the radio base stations 20A, 20B, 20C, and 20D performs radio communication with the radio terminal station 10 using different radio frequencies. Further, the same ESS-ID is set in each of the radio base stations 20A, 20B, 20C, and 20D. When communicating by connecting to a wireless LAN, the wireless terminal station 10 selects any wireless base station using one ESS-ID among the wireless base stations 20A, 20B, 20C, and 20D. Can be connected.

  The radio terminal station 10 is registered in advance with a radio frequency when communicating by connecting to a wireless LAN. In this example, since the radio terminal station 10 may be connected to all four radio base stations 20A, 20B, 20C, and 20D included in the sub-network, all the radio base stations 20A, 20B, 20C, and 20D are connected. Radio frequencies are registered in advance. Hereinafter, the radio frequencies of the radio base stations 20A, 20B, 20C, and 20D registered in advance in the radio terminal station 10 are referred to as registration set frequencies. For example, all the radio frequencies of the radio base stations 20A, 20B, 20C, and 20D are stored in advance in the memory of the wireless LAN module 40 as registered set frequencies.

  Each of the radio base stations 20A, 20B, 20C, and 20D transmits a beacon signal having a different frequency at a predetermined timing. In this case, the radio base stations 20A, 20B, 20C, and 20D transmit beacon signals at different timings so that a plurality of base stations do not transmit beacon signals at the same time.

  A user of the wireless terminal station 10 (hereinafter simply referred to as a user) activates the wireless terminal station 10 when starting communication via the wireless LAN (step S11). For example, the user turns on the power of the wireless LAN module 40 and the PC 50 to start the wireless terminal station 10 and operates the PC 50 to input a connection instruction to the wireless LAN. When the activation operation is performed by the user, the CPU 45 of the wireless LAN module 40 performs initialization processing of each block included in the wireless LAN module 40. In the present embodiment, the initialization process is a process in which the CPU 45 starts processing according to a program, the transmission / reception frequency of each module included in the wireless LAN module 40 is set, and the wireless terminal station 10 transmits and receives packets. It is a series of processing until it becomes possible.

  When the initialization process is executed, control data can be transmitted and received between the CPU 45 and the PC 50 via the PC interface unit 41. When the initialization process is executed, the RF unit 44 can receive a packet or transmit a packet as a radio signal.

  In the initialization process, the CPU 45 determines the transmission / reception frequencies of the RF unit 44 and the modem unit 43 from the radio frequencies of the four radio base stations 20A, 20B, 20C, and 20D based on the registered setting frequencies registered in advance. Set the frequency to one of them. For example, during the initialization process, the CPU 45 sets the transmission / reception frequency of the RF unit 44 and the modem unit 43 to a frequency corresponding to the lowest frequency among the radio frequencies of the radio base stations 20A, 20B, 20C, and 20D. For example, during the initialization process, the CPU 45 sets the transmission / reception frequency of the RF unit 44 and the modem unit 43 to a frequency corresponding to the highest frequency among the radio frequencies of the radio base stations 20A, 20B, 20C, and 20D. To do.

  When the initialization process is completed, the RF unit 44 receives a beacon signal from the radio base station. In the present embodiment, an example will be described in which the RF unit 44 first receives a beacon signal from the radio base station 20A after the initialization process is completed. The RF unit 44 converts the received beacon signal into a baseband modulation signal and outputs the baseband modulation signal to the modem unit 43. The baseband modulation signal from the RF unit 44 is demodulated and output to the MAC unit 42.

  The beacon identifying unit 81 of the MAC unit 42 determines whether or not the received packet from the modem unit 43 is a beacon signal. If it is determined that the signal is a beacon signal, the beacon identifying unit 81 outputs the received packet to the beacon processing unit 82.

  The beacon processing unit 82 extracts beacon information included in the beacon signal from the beacon identifying unit 81 according to the control of the CPU 45 (step S12). The beacon information includes hardware information used in each hardware module (not shown) other than the beacon control unit in the MAC unit 42 and software information used in software processing executed by the CPU 45. The beacon processing unit 82 outputs the hardware information in the beacon information to each hardware module other than the beacon control unit in the MAC unit 42. In addition, the beacon processing unit 82 stores software information in the beacon information in the register 83. The software information stored in the register 83 is extracted and processed by the CPU 45.

  Further, the beacon processing unit 82 calculates the reception power of the beacon signal according to the control of the CPU 45. In this example, the RF unit 44 receives a beacon signal for a predetermined time. Then, the beacon processing unit 82 calculates an average value of received power of beacon signals received within a predetermined time as average received power.

  Further, the beacon processing unit 82 extracts connection number information included in the beacon signal. Since the RF unit 44 receives a beacon signal for a predetermined time as described above, the beacon processing unit 82 extracts connection number information from the last received beacon signal among the beacon signals received within the predetermined time. .

  When the beacon information is extracted, the CPU 45 determines whether there is another registered set frequency (step S13). When determining that there is another registered set frequency, the CPU 45 switches the frequency of a local oscillator (not shown) inside the wireless LAN module 40 to change the transmission / reception frequencies of the RF unit 44 and the modem unit 43 (step S14). . And the process of step S12 is repeatedly performed about all the registration setting frequencies.

  In this example, when the processing of step S12 is completed for the registration set frequency of the radio base station 20A, there are other registration set frequencies of the radio base stations 20B, 20C, and 20D, so the CPU 45 is based on the registration set frequency, for example. The transmission / reception frequency of the RF unit 44 and the modem unit 43 is changed to a frequency corresponding to the radio frequency of the radio base station 20B. And the radio | wireless terminal station 10 performs the process of step S12 about the radio base station 20B similarly to 20 A of radio base stations.

  By repeatedly executing the above process, the radio terminal station 10 executes the process of step S12 for all radio frequencies of the radio base stations 20A, 20B, 20C, and 20D. That is, the radio terminal station 10 calculates the average received power of all the beacon signals of the radio base stations 20A, 20B, 20C, and 20D, and extracts the connection number information of all the radio base stations 20A, 20B, 20C, and 20D.

  When the process of step S12 is executed for all the set frequencies and it is determined that there is no other registered set frequency, the CPU 45 determines, among the average received power of the beacon signals received from the radio base stations 20A, 20B, 20C, and 20D, It is determined whether or not there is a value larger than a predetermined threshold value (step S15). In the present embodiment, a case will be described in which the lower limit value of the received power when the transfer rate on the wireless transmission path is maximum is set as the threshold value. Hereinafter, the transfer rate at the maximum on the wireless transmission path is referred to as the maximum rate. The threshold value is not limited to the value shown in the present embodiment, and may be an arbitrary value set by the user, for example.

  If it is determined that there is a radio base station whose average received power is greater than the threshold, the CPU 45 communicates at a maximum rate with the radio base station whose average received power is greater than the threshold among the radio base stations 20A, 20B, 20C, and 20D. Identify all possible radio base stations. The CPU 45 compares the number of connections of the wireless terminal stations of each specified wireless base station based on the number of connections information. Then, the CPU 45 selects a radio base station with the smallest number of connection of radio terminal stations. That is, the CPU 45 selects a radio base station with the smallest load among the identified radio base stations. Then, the CPU 45 transmits a connection request to the selected radio base station and executes a connection process (step S16).

  For example, when the average received power of the beacon signals received from the radio base stations 20A, 20B, and 20C is larger than the threshold and the average received power of the beacon signals received from the radio base station 20D is equal to or less than the threshold, the CPU 45 Radio base stations 20A, 20B, and 20C are specified as radio base stations that can communicate at the maximum rate. When the number of wireless terminal stations connected to the wireless base station 20B is the smallest among the wireless base stations 20A, 20B, and 20C, the CPU 45 selects the wireless base station 20B as the wireless base station with the smallest load. . Then, the CPU 45 transmits a connection request to the radio base station 20B and executes a connection process.

  When determining that there is no radio base station whose average received power is larger than the threshold, the CPU 45 selects a radio base station having the highest average received power among the radio base stations 20A, 20B, 20C, and 20D. That is, since there is no radio base station that can communicate at the maximum rate, the CPU 45 has the highest transfer rate among the radio base stations 20A, 20B, 20C, and 20D even if the maximum rate is not reached. Select. Then, the CPU 45 transmits a connection request to the selected radio base station and executes a connection process (step S17).

  For example, when all the average received powers of beacon signals received from the radio base stations 20A, 20B, 20C, and 20D are equal to or less than the threshold, the CPU 45 is the most among the radio base stations 20A, 20B, 20C, and 20D. A radio base station having a large average received power is selected. For example, when the average received power of the radio base station 20C is the maximum among the radio base stations 20A, 20B, 20C, and 20D, the CPU 45 selects the radio base station 20C. Then, the CPU 45 transmits a connection request to the radio base station 20C and executes a connection process.

  As described above, according to the present embodiment, when the radio terminal station 10 belongs to a radio base station, the radio base station 10 is based on the beacon signals received from all the radio base stations included in the subnetwork. Collect information on the received power and the number of connected wireless terminal stations. Then, the radio terminal station 10 selects and connects a radio base station based on the received power and the information on the number of connections of the radio terminal station.

  Since the reception power of each wireless base station and the number of connections of wireless terminal stations are determined at the start of communication, the wireless terminal station 10 can perform efficient communication even when a new communication is started. A base station can be automatically selected. Further, among all the radio base stations included in the sub-network, a radio base station that meets a predetermined reception condition and has the smallest number of connection of radio terminal stations is selected, so that the load on the entire sub-network can be distributed. . Therefore, efficient communication can be performed even when communication is newly started, and the load on the entire subnetwork can be distributed.

  In the base station selection system according to the present invention, even when a new communication is started in a sub-network such as a wireless LAN, a radio base that can perform the most efficient communication among all the radio base stations included in the sub-network. The wireless terminal station can automatically select and connect the stations, and efficient communication can be performed even when communication is newly started. In addition, it is possible to distribute the load on the entire subnetwork such as a wireless LAN.

It is a block diagram which shows an example of a structure of the base station selection system by this invention. It is a block diagram which shows an example of a structure of a radio | wireless terminal station. It is a block diagram which shows an example of a structure of a wireless base station. It is a block diagram which shows an example of a structure of a beacon control part. It is a flowchart which shows an example of the selection process of a radio base station.

Explanation of symbols

10 wireless terminal stations 20A, 20B, 20C, 20D wireless base station 30 wired network 40, 60 wireless LAN module 41, 61 PC interface unit 42, 62 MAC unit 43, 63 modem unit 44, 64 RF unit 45, 65 CPU
50 pcs
70 CPU board 81 Beacon identification unit 82 Beacon processing unit 83 Register

Claims (11)

A base station selection system in which a radio terminal station selects an associated radio base station from the plurality of radio base stations in a communication network including a plurality of radio base stations,
The radio base station includes signal transmission means for transmitting a radio signal including connection number information indicating the number of radio terminal stations connected to the radio base station,
The wireless terminal station
A signal receiving means for receiving radio signals from all radio base stations included in the communication network when belonging to a radio base station;
Base station selection means for selecting one radio base station among all radio base stations included in the communication network based on received power of the received radio signal and connection number information included in the radio signal. A base station selection system characterized by that. The wireless terminal station
Connection number information extracting means for extracting connection number information from the received radio signal;
Received power calculation means for calculating received power of the received radio signal;
A base station specifying means for specifying all of the radio base stations included in the communication network, the radio base stations for which the calculated received power is greater than a predetermined value,
The base station selection means is a wireless base station having the smallest number of connected wireless terminal stations among the wireless base stations specified by the base station specifying means based on the connection number information extracted by the connection number information extracting means. The base station selection system according to claim 1, wherein a station is selected.   When there is no radio base station whose reception power is greater than a predetermined value, the base station selection means selects a radio base station corresponding to the largest reception power among all the radio base stations included in the communication network. The base station selection system according to claim 2. The signal receiving means receives a radio signal over a predetermined time for each radio base station,
The received power calculation means calculates an average received power that is an average value of the received power of the radio signal received during the predetermined time,
The base station selection system according to claim 2, wherein the base station specifying means specifies all of the radio base stations whose average received power is greater than a predetermined value among all the radio base stations included in the communication network.   5. The base station selection system according to claim 4, wherein the connection number information extraction means extracts connection number information from the last received radio signal among radio signals received during a predetermined period.   When there is no radio base station whose average received power is greater than a predetermined value, the base station selecting means is a radio base station corresponding to the largest average received power among all the radio base stations included in the communication network. The base station selection system according to claim 4 or 5, which selects The signal transmission means transmits radio signals of different frequencies for each radio base station,
The radio terminal station includes a registration unit that pre-registers frequencies of radio signals transmitted by all radio base stations included in the communication network,
The signal receiving unit receives radio signals from all radio base stations included in the communication network based on each frequency registered by the registration unit. Base station selection system.   The base station selection system according to any one of claims 1 to 7, further comprising base station connection means for connecting to a radio base station selected by the base station selection means.   The base station selection system according to any one of claims 1 to 8, wherein the signal transmission means transmits a beacon signal including connection number information as a radio signal. A base station selection method in which a radio terminal station selects an associated radio base station from the plurality of radio base stations in a communication network including a plurality of radio base stations,
A radio base station transmitting a radio signal including connection number information indicating the number of radio terminal stations connected to the radio base station;
When a wireless terminal station belongs to a wireless base station, receiving wireless signals from all wireless base stations included in the communication network; and
A radio terminal station selecting one radio base station among all radio base stations included in the communication network based on received power of the received radio signal and connection number information included in the radio signal; A base station selection method comprising: A step in which the wireless terminal station extracts connection number information from the received wireless signal;
The wireless terminal station calculating received power of the received wireless signal;
The wireless terminal station specifies all wireless base stations whose calculated received power is greater than a predetermined value, out of all wireless base stations included in the communication network;
The base station according to claim 10, further comprising: a step of selecting a radio base station with the smallest number of connected radio terminal stations from among the identified radio base stations based on the extracted connection number information. Station selection method.

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