JP2010114698A - Wireless communication system - Google Patents

Abstract

【Task】
The purpose is to correct the difference in radio field intensity emitted by the macrocell base station and the femtocell base station.
[Solution]
In a radio communication system, a macro cell base station stores radio channel information used in a femto cell base station and a received power correction value to be applied to the radio channel, and broadcasts it to radio mobile stations in the area as broadcast information. In addition, the wireless mobile station compares the reception intensity value of the radio wave received from the macro cell base station with the value obtained by adding the reception power correction value to the reception intensity of the radio wave received from the femtocell base station. If the reception strength value of the radio wave received from is larger, a connection request is transmitted to the macro cell base station, and the received power correction value is added to the reception strength of the radio wave received from the femtocell base station. If it is larger, a connection request is transmitted to the macro cell base station.
[Selection] Figure 1

Description

  The present invention relates to a radio communication system that performs communication between a radio mobile station and a plurality of radio base stations.

  In a mobile communication system, communication is performed between a radio base station and a radio mobile device using a finite frequency band. Conventionally, a wireless mobile station establishes a connection and communicates with a wireless base station that emits a radio wave having the strongest reception intensity among receivable wireless channels. However, in the future, it is conceivable to use a system in which a large number of wireless base stations having a small communication area (communication area) are installed. In this case, the radio waves radiated from each wireless base station may be weaker than existing wireless base stations. Conceivable.

  For this reason, it is conceivable that a radio mobile station is difficult to connect to a radio base station with a small communication area installed near an existing radio base station. However, intensifying the radiated radio waves of a radio base station with a small communication area leads to expansion of the communication area, which is a problem.

JP-A-5-41687

  In a mobile communication system, communication is performed between a radio base station and a radio mobile device using a finite frequency band. Since the frequency band that can be used by one radio base station is finite, the number of users that can be accommodated by one radio base station is also finite. In addition, there is a dead spot where radio waves do not reach from a macrocell base station that has been conventionally laid. In order to solve these problems, in the future, it is conceivable to install a base station (hereinafter referred to as a femtocell base station) having a small accommodation cell radius and capable of being installed inexpensively.

  The femtocell base station has a cell radius of about several meters and is connected to the core network using a general public communication network. The femtocell base station is assumed to be installed regardless of the macrocell design such as a general home or office.

  Also, the access fee to the femtocell network may be set lower than the access fee to the existing macro cell network because of the advantages of the above-mentioned coverage area expansion and frequency utilization efficiency improvement.

  For the above reasons, wireless mobile station users want to communicate by connecting to femtocell base stations rather than macrocell base stations. However, the current wireless mobile station selects and accesses a base station with strong received power intensity. Therefore, a problem is that a radio mobile station is difficult to access a femtocell base station installed near a macrocell base station that emits strong radio waves.

  In order to solve the above problems, femtocell base stations need to emit stronger radio waves, but if many base stations that emit strong radio waves are installed, radio interference between base stations is a problem. Therefore, it is difficult for the femtocell base station to emit a strong radio wave.

  In Patent Document 1, it is possible to select an optimal base station in consideration of the difference in service contents of the base station. However, when there are two macro cell base stations and femto cell base stations, wireless mobile A configuration for a station to properly access a femtocell base station is not disclosed.

  In order to solve this problem, an object of the present invention is to correct a difference in radio field intensity emitted from a macro cell base station and a femto cell base station without increasing the radio field intensity actually emitted from the femto cell base station.

  In a radio communication system having a radio mobile station capable of accessing a base station of both a macro cell base station and a femto cell base station, the macro cell base station includes radio channel information used in the femto cell base station, and the radio The received power correction value to be applied to the channel is stored and broadcasted to the mobile radio stations in the area as broadcast information. In addition, the wireless mobile station compares the reception intensity value of the radio wave received from the macro cell base station with the value obtained by adding the reception power correction value to the reception intensity of the radio wave received from the femtocell base station. If the reception strength value of the radio wave received from is higher, a connection request is transmitted to the macro cell base station, and the reception power correction value is added to the reception strength of the radio wave received from the femtocell base station. If it is larger, a connection request is transmitted to the femtocell base station.

  A wireless mobile station can easily connect to a femtocell base station with a weak output installed near a macrocell base station with a strong output. In addition, since the wireless mobile station can easily connect to the femtocell base station, the finite frequency resources of the macrocell base station can be used effectively.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a network configuration diagram showing an embodiment of a mobile communication system according to the present invention. The mobile communication system includes a radio mobile station 20, macro cell base stations 30-1 and 30-2 connected to the radio mobile station through radio channels, macro cells 101 and 102 formed by radio wave coverage of the macro cell base station, A macro cell base station controller 105 connected to and controlled by the base station, a macro cell billing server 106 that charges for radio access from the macro cell base station, a macro cell core network 110 comprising the macro cell base station controller and the macro cell billing server, Femtocell base stations 40-1 and 40-2 connected to a radio mobile station through a radio channel, femtocells 103 and 104 formed in the radio wave coverage of the femtocell base station, and between the femtocell base station and the femtocell core network A femtocell router 107 serving as a firewall, A femtocell base station controller 108 connected to and controlled by the tocel base station, a femtocell charging server 109 for charging wireless access from the femtocell base station, a femtocell router, a femtocell base station controller, and a femtocell A femtocell core network 111 composed of a billing server.

  FIG. 2 is a block diagram illustrating a configuration example of the radio mobile station 20. The radio mobile station 20 includes an antenna 200, an RF unit 210, a signal conversion unit 220, a control unit 230, a base station selection unit 240, and a peripheral device unit 250, and a radio channel with the macro cell base station 30 or the femto cell base station 40. Data communication is performed by setting. The RF unit 210 transmits / receives a radio signal to / from the macro cell base station 30 or the femto cell base station 40 via the antenna 200 and notifies the received power value to the base station selection unit 240. The signal conversion unit 220 performs radio signal modulation / demodulation processing. The control unit 230 includes a communication processing unit 231 and a message receiving unit 232 in addition to processing for connecting to and releasing from the radio channel with the base station 30. The communication processing unit 231 transmits and receives the control signal modulated / demodulated by the signal conversion unit 220 and performs wireless protocol processing with the macro cell core network 110 or the femto cell core network 111. The message receiving unit 232 receives and analyzes broadcast information from the macrocell base station 30. The base station selection unit 240 includes a reception strength determination function 241 and a reception power storage unit 242, and the reception power storage unit 242 stores the reception power location notified from the RF unit 210. The reception strength determination function 241 determines the reception strength of each radio channel from the reception strength of each radio channel received by the RF unit 210 and the broadcast information received by the message reception unit 232, and notifies the control unit of the determination result. The peripheral device unit 250 includes an input unit 251 configured with buttons for inputting, a display unit 252 including an LCD or LED for displaying information such as a message, and a speaker 253.

  FIG. 3 is a block diagram illustrating a configuration example of the macro cell base station 30. The macrocell base station 30 includes an antenna 300, an RF unit 310, a signal conversion unit 320, a control unit 330, a storage device 340, and a network IF unit 350, and performs data communication with the radio mobile station 20 by setting a radio channel. Do. The RF unit 310 transmits / receives a radio signal to / from the radio mobile station 20 via the antenna 300. The signal converter 320 performs a radio signal modulation / demodulation process. The control unit 330 includes a communication processing unit 331 that performs processing for setting and releasing a wireless channel with the wireless mobile station 20 and a notification information function unit 332 that distributes notification information to the wireless mobile station 20. The storage device 340 includes a system parameter 341 for setting a unique parameter for each macro cell base station, a femto base station channel information table 342 for managing radio channels used in the femto cell base station installed in the macro cell, Is provided. The network IF unit 350 interfaces with the macrocell base station control device 105.

  FIG. 4 is a block diagram illustrating a configuration example of the femtocell base station 40. The femtocell base station 40 includes an antenna 400, an RF unit 410, a signal conversion unit 420, a control unit 430, a storage device 440, and a network IF unit 450, and performs data communication by setting a radio channel with the radio mobile station 20. I do. The RF unit 410 transmits / receives a radio signal to / from the radio mobile station 20 via the antenna 400. The signal conversion unit 420 performs modulation / demodulation processing of a radio signal. The control unit 430 includes a communication processing unit 431 that performs processing for setting and releasing a wireless channel with the wireless mobile station 20. The storage device 440 includes a system parameter 441 for setting a unique parameter for each femtocell base station. The network IF unit 450 serves as an interface with the femtocell base station controller 108.

  FIG. 5 shows an operation sequence when the wireless mobile station existing at the position of the wireless mobile station 20 in FIG. 1 transitions from the power OFF state to the power ON state. When the wireless mobile station 20 is turned on, the wireless channel reception strength 502 from the surrounding femtocell base station 40 and the wireless channel reception strength 503 from the surrounding macrocell base station 30 are received. Thereafter, the reception strength determination function 241 in the wireless mobile station 20 compares the reception strength of each wireless channel. If the radio channel reception strength 503 from the macrocell base station 30 is stronger as a result of the reception strength comparison 241a, the radio channel with the macrocell base station 30 is selected and communication is performed.

  6 and 7 show an operation sequence when the radio mobile station existing at the position of the radio mobile station 20 in FIG. 1 transitions from the power-off state to the power-on state when the present invention is applied. When the wireless mobile station 20 is turned on, the wireless channel reception strength 602 from the surrounding femtocell base station 40 and the wireless channel reception strength 603 from the surrounding macrocell base station 30 are received. The RF unit 210 notifies the received radio channel reception strength to the base station selection unit 240 in the form of received radio channel information 802 and a received strength value 803 as shown in FIG. The macro cell base station 30 distributes the broadcast information 604 to the radio mobile stations existing in the own cell.

  The broadcast information will be described with reference to FIG. The broadcast information includes a broadcast information identifier 901, conventional broadcast information 902, a femtocell base station radio channel 903, and a received intensity correction value 904 for the femtocell base station radio channel. The message receiving unit 232 that has received the broadcast information 604 from the macrocell base station selects the femtocell base station radio channel 903 and the received intensity correction value 904 for the femtocell base station radio channel included in the broadcast information 604 as base station selection. Notification to the unit 240. The base station selection unit 240 that has received the radio channel reception strength 602 from the femtocell base station, the radio channel reception strength 603 from the macrocell base station, and the broadcast information 604 from the macrocell base station, receives the received femtocell base station Is added to the radio channel reception intensity 602 from the broadcast information, and the radio channel reception intensity 603 from the macrocell base station is compared with the reception intensity of each radio channel.

となったときには、上記の結果を基地局選択部２４０は、通信制御部２３１に通知し、通信制御部２３１はフェムトセル基地局４０へコネクション要求６０５を送信する。

となったときには、上記の結果を基地局選択部２４０は、通信制御部２３１に通知し、通信制御部２３１はマクロセル基地局４０へコネクション要求を送信する。 When the radio channel reception strength 602 from the femtocell base station is Rxfe, the radio channel reception strength 603 from the macrocell base station is Rxma, and the reception strength correction value 904 extracted from the broadcast information is Rxadd,

At this time, the base station selection unit 240 notifies the communication control unit 231 of the above result, and the communication control unit 231 transmits a connection request 605 to the femtocell base station 40.

At this time, the base station selection unit 240 notifies the communication control unit 231 of the above result, and the communication control unit 231 transmits a connection request to the macrocell base station 40.

It is a figure explaining a network structure. It is a figure explaining the radio | wireless mobile station used by a present Example. It is a figure explaining the macrocell base station used by a present Example. It is a figure explaining the femtocell base station used in a present Example. It is a figure explaining the base station selection of the conventional radio | wireless mobile station. It is a figure explaining the base station selection of the radio | wireless mobile station which applied the present Example. It is a figure explaining the sequence between modules in the base station selection of the radio | wireless mobile station which applied the present Example. It is a figure explaining the receiving strength information used by a present Example. It is a figure explaining the information alert | reported from a macrocell base station in a present Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Wireless mobile station, 30 ... Macro cell base station, 40 ... Femto cell base station, 101 ... Macro cell 1, 102 ... Macro cell 2, 103 ... Femto cell 1, 104 ... Femto cell 2, 105 ... Macro cell base station control apparatus, 106 DESCRIPTION OF SYMBOLS ... Macrocell charging server, 107 ... Femtocell router, 108 ... Femtocell base station controller, 109 ... Femtocell charging server, 110 ... Macrocell core network, 111 ... Femtocell core network, 200 ... Antenna, 210 ... RF unit, 220 ... Signal conversion unit, 230 ... Control unit, 231 ... Communication processing unit, 232 ... Message reception unit, 240 ... Base station selection unit, 241 ... Reception strength determination unit, 242 ... Reception strength storage unit, 250 ... Peripheral device, 251 ... Input unit, 252 ... display unit, 253 ... speaker, 300 ... antenna, DESCRIPTION OF SYMBOLS 10 ... RF part, 320 ... Signal conversion part, 330 ... Control part, 331 ... Communication processing part, 332 ... Broadcast information control part, 340 ... Memory | storage device, 341 ... System parameter, 342 ... Femtocell base station channel information table, 350 ... core network interface, 400 ... antenna, 410 ... RF unit, 420 ... signal conversion unit, 430 ... control unit, 431 ... communication processing unit, 440 ... storage device, 441 ... system parameter, 442 ... radio channel information table, 450 ... Network IF unit, 801 ... reception intensity information, 802 ... reception radio channel, 803 ... reception intensity value, 901 ... broadcast information identifier, 902 ... conventional broadcast information, 903 ... femtocell base station radio channel, 904 ... reception intensity correction value,

Claims (1)

In a wireless communication system that performs communication between a wireless mobile station and a plurality of wireless base stations,
The first radio base station having a large communication area calculates a reception power correction value to be added to the power of the radio wave reception intensity based on the radio channel information of the second radio base station having a small communication area, and the radio mobile station A control unit for informing
The wireless mobile station receives a value of the reception intensity of the radio wave received from the first radio base station, and a value obtained by adding the reception power correction value to the reception intensity of the radio wave received from the second radio base station. In comparison, if the reception intensity value of the radio wave received from the first radio base station is larger, a connection request is transmitted to the first radio base station and received from the second radio base station. And a base station selection unit that transmits a connection request to the second radio base station when the value obtained by adding the received power correction value to the received radio wave reception intensity is larger. .

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