JP2014036317A - Radio communication system and radio communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that prevents access from concentrating in radio communication of a particular communication mode and preferentially performs connection by expanding a network area of another communication mode.SOLUTION: A radio communication system 10 obtains in advance information indicating a first network area provided by a second base station at normal times, and a second network area provided at the time of beam forming. At this time, a handover control unit 17 determines switching to the second communication mode if a radio terminal 11 performing communication by the first communication mode is situated in the first network area, and determines switching to the second communication mode after getting the radio terminal 11 to perform beam forming if it is not situated in the first network area but in the second network area. If the handover control unit 17 has determined switching to the second communication mode, it performs handover to switch the communication destination of the radio terminal 11 from a first radio base station 12 to a second radio base station 13.

Description

  The present invention relates to a wireless communication system and a wireless communication control method, and is suitable for application to a hybrid wireless communication system and a wireless communication control method capable of wireless communication using a plurality of communication methods.

  In recent years, a wireless communication system used for mobile terminal communication is a hybrid type in which a plurality of wireless communication systems can be provided to a wireless terminal in place of a conventional wireless communication system that provides a single wireless communication system to the wireless terminal. Demand for wireless communication systems is increasing. In a hybrid wireless communication system, it is required to perform a handover for switching a communication destination base station of a wireless terminal between the wireless communication systems stably and quickly in accordance with the usage status of the wireless terminal.

  In general, handover is performed based on processing procedures of “network discovery”, “network selection”, and “network switching”. In the “network discovery” process, a search is made as to what kind of characteristics exist in the vicinity of the wireless terminal. In the “network selection” process, a network that satisfies the requirements of the user and the application to be used with respect to the communication fee, communication quality, communication stability, etc. is selected from the networks discovered by “network discovery”. When performing handover between different types of wireless communication systems, network selection is performed in consideration of the existence of a plurality of wireless communication systems. In “network switching”, the communication destination of the wireless terminal is switched using the wireless base station that provides the radio waves of the network selected in “network selection” as the handover destination.

  As a wireless communication system that performs handover between wireless communication systems, for example, Patent Document 1 describes a connection system between different networks that realizes handover of wireless terminals to various wireless communication systems. In the heterogeneous network connection system described in Patent Document 1, in the area where the communication area of the 3GPP (Third Generation Partnership Project) wireless communication system and the communication area of the WLAN (Wireless Local Area Network) communication system overlap, When the terminal device moves to the communication area of the second access point of the WLAN communication system while communicating with the first access point of the WLAN communication system, the mobile terminal device temporarily moves the communication session to the 3GPP wireless communication system, Seamless handover between IP subnets in a WLAN by preparing for connection with the second access point while communicating in the 3GPP wireless communication system, and handing over to the second access point after the connection preparation is completed Is realized.

  Further, for example, Patent Document 2 describes a handover control system that controls handover between the same or different radio systems. In the handover control system described in Patent Document 2, the handover control device on the network side selects a handover method that satisfies the request of the mobile terminal based on the type information of the wireless system notified from the mobile terminal, thereby enabling the mobile terminal Since it is not necessary to select a handover method on the side, it is possible to reduce the handover control processing on the mobile terminal side and simplify the mobile terminal apparatus.

JP 2006-229831 A JP 2004-260444 A

  In the hybrid type wireless communication system as described above, by switching the communication destination wireless communication system by handover, the advantages of each of the plurality of wireless communication systems can be used, and the performance of the communication service that can be provided to the user can be improved. Can be improved.

  For example, a hybrid wireless communication system provides a wide range of stable network areas but a communication speed that is not so high, and a high-speed wireless communication system that provides a narrow network area but a high communication speed. Assume that communication is possible. At this time, the hybrid wireless communication system can provide a stable communication environment by connecting to a wide-range wireless communication system during normal times. When the wireless terminal exists in the network area of the high-speed wireless communication system, the hybrid wireless communication system can provide high-speed communication by handover from the wide-range wireless communication system to the high-speed wireless communication system. it can. Further, by maintaining the connection to the high-speed wireless communication system as long as the wireless terminal exists in the network area of the high-speed wireless communication system, the hybrid wireless communication system can provide the user with a high-speed communication environment. Can be lengthened.

  However, in a hybrid type radio communication system, when communication destinations are biased to a specific radio communication system due to a small number of handover execution opportunities, an adverse effect due to concentration of access can be considered. If the communication rate is low, the rate at which a high-speed communication environment can be provided is suppressed, and the overall communication speed is not improved. In order to solve such a problem, it is expected to realize a hybrid type radio communication system capable of positively executing a handover to a radio communication system having a high communication speed.

  However, in the inter-heterogeneous network connection system described in Patent Document 1 and the handover control system described in Patent Document 2, there is a wireless terminal in the network area where the communication service is provided in the “network discovery” process. Otherwise, the handover destination cannot be found and it is difficult to actively execute the handover.

  The present invention has been made in view of the above points, and can prevent concentration of access to wireless communication of a specific communication method, and can preferentially connect by expanding a network area in another communication method. A hybrid wireless communication system and a wireless communication control method that can be used are proposed.

  In order to solve this problem, in the present invention, in a wireless communication system capable of wireless communication using a plurality of different communication methods, a first wireless base station that provides a network area corresponding to the first communication method, A second wireless base station that provides a network area corresponding to the communication method; a first communication system for performing wireless communication with the first wireless base station using the first communication method; and the second communication. A wireless terminal having a second communication system for performing wireless communication with the second wireless base station in a method, and acquiring and storing base station information regarding the second wireless base station from the second wireless base station The communication method used by the wireless terminal based on the position information server, the terminal position information indicating the position of the wireless terminal, and the base station information stored in the position information server. Wireless communication system and a handover control unit that controls the communication method to preferentially selected is provided. In this radio communication system, the base station information includes information indicating a first network area that can be provided when the second radio base station does not perform beamforming, and beam forming by the second radio base station. Information indicating a second network area that can be expanded and provided at the time of execution, and the handover control unit includes the wireless terminal in communication with the first communication method in the first network area. If so, it is decided to switch to the second communication method, and even if the wireless terminal communicating with the first communication method does not exist in the first network area, the second network is used. If present in the area, switch to the second communication method after causing the second radio base station to perform beam forming for the radio terminal When the handover control unit decides to switch to the second communication method, the handover control unit performs handover and sets the radio base station to which the radio terminal communicates as the first radio base station. To the second radio base station.

  In order to solve such a problem, the present invention provides a wireless communication control method for controlling a communication method used by the wireless terminal in a wireless communication system capable of wireless communication with a plurality of different communication methods. In this wireless communication control method, the wireless communication system provides a first wireless base station that provides a network area corresponding to the first communication method, and a network area that corresponds to the second communication method. Wireless communication with the first radio base station in the first communication scheme and the second radio base station in the second communication scheme. A wireless terminal having a second communication system for performing communication, a location information server for acquiring and storing base station information related to the second wireless base station from the second wireless base station, and a location of the wireless terminal The communication method used by the wireless terminal is controlled to preferentially select the second communication method based on the terminal location information indicating the location information and the base station information stored in the location information server. The base station information includes information indicating a first network area that can be provided when the second radio base station does not perform beamforming, and the second radio base station. Includes information indicating a second network area that can be expanded and provided during execution of beamforming. In the wireless communication control method, the handover control unit switches to the second communication method when the wireless terminal communicating with the first communication method exists in the first network area. A first step of determining the second network area even when the handover control unit is not in the first network area and the wireless terminal in communication with the first communication method is not present. A second step of deciding to switch to the second communication method after causing the second radio base station to perform beam forming for the radio terminal, and the handover controller However, if it is decided to switch to the second communication method, handover is performed and the radio base station with which the radio terminal communicates is changed to the first radio base And a third step of switching to the second radio base station from.

  According to the present invention, in a hybrid wireless communication system capable of wireless communication with a plurality of communication methods, it is possible to prevent access from being concentrated on wireless communication of a specific communication method, and to provide a network provided by another communication method. The area can be enlarged and connected with priority.

It is a block diagram which shows the structure of the radio | wireless communications system by one embodiment of this invention. It is an example of a structure of the base station information table stored in the position information server. It is a block diagram which shows the structure of the radio | wireless terminal shown in FIG. It is a block diagram which shows the structure of the signal processing part shown in FIG. It is a sequence diagram which shows the process sequence which determines a beam target direction. FIG. 2 is a sequence diagram showing a flow of processing from the start of communication by the 1xEVDO method to handover determination in the wireless communication system shown in FIG. 1. 2 is a flowchart illustrating a processing procedure of handover determination performed at the time of communication by the 1xEVDO method in the wireless communication system illustrated in FIG. 1. It is a flowchart which shows the process sequence of the intersystem handover to a WiFi system. FIG. 2 is a sequence diagram illustrating a flow of processing for performing inter-system handover from a WiFi system to a 1xEVDO system in the wireless communication system illustrated in FIG. 1. 2 is a flowchart illustrating a processing procedure of handover determination performed at the time of communication using the WiFi scheme in the wireless communication system illustrated in FIG. 1. It is an image figure which shows the change of the network area by execution of beam forming. It is a structural example of the slot frame of the signal transmitted and received by the radio base station that is executing beamforming.

(1) One Embodiment of the Present Invention A wireless communication system according to one embodiment of the present invention is a hybrid capable of wireless communication using a plurality of different communication methods (for example, a first communication method and a second communication method). Type wireless communication system, by updating and holding information about the wireless base station of the second communication method, not only the range (network area) in which communication is possible in the second communication method, but also the second Assuming network areas that can be expanded by executing beamforming in the communication method (network areas during beamforming), the system determines whether to perform handover between systems based on these network areas and the location of wireless terminals. The terminal is controlled to increase the opportunity to perform wireless communication by the second communication method.

  For example, the wireless communication system according to the embodiment of the present invention performs an inter-system handover when a wireless terminal communicating with the first communication method exists in the network area of the second communication method. Switch to wireless communication by the second communication method. In addition, the wireless communication system according to the embodiment of the present invention has a beam forming and system when a wireless terminal communicating with the first communication method is present in the network area during beam forming of the second communication method. Inter-handover is executed, and the wireless communication is switched to the second communication method.

  Here, beam forming is a technique for controlling each antenna according to the state of a propagation path in which the power and phase transmitted from a plurality of antennas fluctuate. By executing beam forming, the target radio terminal and radio base The network area can be expanded around the station. In the radio communication system according to the present embodiment, it is assumed that both the radio terminal and the radio base station can execute beam forming.

(1-1) Configuration of Radio Communication System A configuration of a radio communication system according to an embodiment of the present invention will be described.

(1-1-1) Overall Configuration FIG. 1 is a block diagram showing a configuration of a wireless communication system according to an embodiment of the present invention. As shown in FIG. 1, the radio communication system 10 includes a radio terminal 11, a first radio base station 12, a second radio base station 13, a first control network 14, a second control network 15, and a home agent 16. A handover control unit 17 and a location information server 18.

  As an example, the wireless terminal 11 conforms to the 1xEVDO (Evolution Data Only) system conforming to the 3GPP2 standard and the IEEE (The Institute of Electrical and Electronics Engineers) 802.11 series wireless LAN (Local Area Network) standard. It is assumed that the mobile phone is compatible with two types of wireless communication systems, such as a certified WiFi (Wireless Fidelity) (registered trademark) system. The 1xEVDO method is an example of a first communication method, and the communication speed is not as high as that of the WiFi method. However, the 1xEVDO method is a communication method that can provide stable wireless communication with a wider network area than the WiFi method. The WiFi system is an example of a second communication system, and the network area to be provided is narrower than the 1xEVDO system, but is a communication system that can provide wireless communication at a higher speed than the 1xEVDO system. The wireless terminal 11 is realized by, for example, a mobile phone, but can also be realized by a movable information processing terminal such as a portable data transceiver or a notebook personal computer.

  The first radio base station 12 is a 1xEVDO radio base station (AP: Access Point) connected to the first control network 14 which is a 1xEVDO system control network, and transmits and receives radio waves to and from the radio terminal 11. Do. The first control network 14 includes a first AP control unit 141 and a PDSN (Packet Data Serving Node) 142. When the wireless terminal 101 performs wireless communication using the 1xEVDO method, the first wireless base station 12 transmits radio waves received from the wireless terminal 11 to the Internet 20 via the first control network 14 and the home agent 16. To transmit.

  The second radio base station 13 is a WiFi radio base station connected to the second control network 15, which is a WiFi control network, and transmits and receives radio waves to and from the radio terminal 11. The second control network 15 includes a second AP control unit 151 and a PDIF (Packet Data Interworking Function) 152. When the wireless terminal 11 performs wireless communication using the WiFi method, the second wireless base station 13 transmits radio waves received from the wireless terminal 11 to the Internet 20 via the second control network 15 and the home agent 16. To transmit.

  The home agent 16 is a router provided on the home link. The home agent 16 is located at the relay point of the first control network 14, the second control network 15, the handover control unit 17, and the Internet 20, and the communication state of the first control network 14 and the second control network 15. To monitor.

  The handover control unit 17 is realized by, for example, a CPU (Central Processing Unit) of a computer and has a function of selecting a communication unit in the wireless terminal 11. Specifically, the handover control unit 17 refers to the location information server 18 when necessary based on the communication status information of the wireless terminal 11 notified via the home agent 16, and is optimal for the wireless terminal 11. A wireless communication system is selected. At this time, if the handover control unit 17 determines that it is necessary to switch the connection destination from the currently communicating wireless communication system to a different wireless communication system, the handover control unit 17 instructs the execution of the inter-system handover, and the currently communicating wireless communication When it is determined that it is necessary to switch the connection destination to another radio base station with the same communication method as the system, the execution of intra-system handover is instructed. A specific execution method of the handover is not particularly limited, and a method generally used as a process of switching the communication connection destination can be used. Further, the handover control unit 17 may be implemented in the location information server 18.

  The location information server 18 is a database server for the WiFi system and has a database as a storage device. The database of the location information server 18 stores a base station information table in which information about each second radio base station 13 is registered.

  Although not shown in FIG. 1 for the sake of brevity, generally, the radio communication system 10 is configured to include a plurality of first radio base stations 12 and a plurality of second radio base stations 13. Each of the first radio base station 12 and the plurality of second radio base stations 13 provides a network area, thereby realizing a wide range of communication services for a large number of radio terminals 11.

(1-1-2) Base Station Information Table FIG. 2 is a configuration example of the base station information table stored in the location information server. 2 includes an SSID field 1811, a MAC address field 1812, a communication method field 1813, an AP position GPS coordinate field 1814, a communicable range GPS coordinate field 1815, a beamforming possible range GPS coordinate field 1816, And a service status column 1817 is provided.

  In the SSID column 1811, an ID for specifying the second radio base station 13 is described, and in the other columns 1812 to 1817 in the bank of the base station information table 181, the second ID specified from the description in the SSID column 1811 is described. Information about the radio base station 13 is described. The information described in FIG. 2 may be stored in the base station information table 181 by transmitting information from each radio base station 13 to the location information server 18 via the handover control unit 17 in advance, for example. The base station information table 181 may be updated by transmitting information from each radio base station 13 to the location information server 18 via the handover control unit 17 in a predetermined cycle.

  The MAC address column 1812 describes the MAC address assigned to the second radio base station 13. The communication method column 1813 describes the classification of communication methods that can be used by the second radio base station 13. For example, from the IEEE 802.11 series that defines the WiFi method, the corresponding detailed classification (a / b / g / N). When “11n” is described in the communication method column 1813, it indicates that the communication method conforms to the IEEE802.11n standard, and when “11b” is described in the communication method column 1813, the IEEE802.11b Indicates that the communication method conforms to the standard.

  In the AP position GPS coordinate column 1814, GPS coordinates indicating the position of the second radio base station 13 are described. For example, the second radio base station 13 is provided with a GPS receiver (not shown), and indicates the position of the second radio base station 13 based on GPS information periodically received by the GPS receiver. GPS coordinates are calculated. Then, the calculated GPS coordinates are transmitted from the second radio base station 13 to the position information server 18 via the handover control unit 17 and described in the AP position GPS coordinate column 1814. In the communicable range GPS coordinate column 1815, GPS coordinates indicating a network area by the second radio base station 13 are described. In general, since the network area by the second radio base station 13 is not a perfect concentric circle or rectangle, for example, GPS coordinates indicating a plurality of points (for example, 4 to 6 points) on the boundary line of the range are described. Then, GPS coordinates that approximate the network area are described.

  The beam forming possible range GPS coordinate column 1816 describes GPS coordinates indicating the network area during beam forming provided by the second radio base station 13 when beam forming is performed. The beam forming possible range GPS coordinate column 1816 describes, for example, GPS coordinates indicating a plurality of points on the boundary line of the network area during beam forming in the same manner as the communicable range GPS coordinate column 1815. 2 indicates that the second radio base station 13 specified from the description in the SSID column cannot execute the beam forming when the beam forming possible range GPS coordinate column 1816 of FIG. 2 indicates “impossible”. Yes.

  In the service status column 1817, the second radio base station 13 specified from the description in the SSID column 1811 performs a radio communication with a service as a radio base station (that is, a radio terminal and relays a call or communication) Whether or not the function is provided. In the service status column 1817 of FIG. 2, “in operation” or “stopped” is described, but actually values corresponding to the items such as “in operation” and “stopped” are described. May be.

(1-1-3) Wireless Terminal FIG. 3 is a block diagram showing a configuration of the wireless terminal shown in FIG. As illustrated in FIG. 3, the wireless terminal 11 includes antennas 101 to 104, an antenna control unit 105, a first wireless IF unit 106, a second wireless IF unit 107, a signal processing unit 108, an external IF 109, and a terminal control unit 110. , A GPS receiver 111, a direction sensor 112, a gyro sensor 113, and an acceleration sensor 114. The wireless terminal 11 realizes a 1xEVDO system for performing wireless communication by the 1xEVDO system and a WiFi system for performing wireless communication by the WiFi system by operating the above-described units.

  Each of the antennas 101 to 104 is an antenna capable of transmitting and receiving a 1xEVDO wireless signal and a WiFi wireless signal. The wireless terminal 11 can cope with beam forming using a four-element antenna using the antennas 101 to 104. The antennas 101 to 104 convert radio waves received from the first radio base station 12 or the second radio base station 13 into signals and output the signals to the antenna control unit 105, and signals input from the antenna control unit 106 Is converted into radio waves and transmitted to the first radio base station 12 or the second radio base station 13.

  The antenna control unit 105 controls connection switching between the antennas 101 to 104 and the first wireless IF unit 106 or the second wireless IF unit 107. The antenna control unit 105 switches between the wireless IF units 106 and 107 serving as connection destinations according to the format of signals input to and output from the antenna control unit 105.

  The first wireless IF unit 106 performs amplification of 1 × EVDO wireless signals and analog / digital signal conversion processing. The second wireless IF unit 107 performs WiFi wireless signal amplification and analog / digital signal conversion processing.

  The signal processing unit 108 performs baseband signal processing such as encoding / decoding processing and modulation / demodulation processing on the wireless signal in accordance with the wireless signal communication method. Specifically, for example, the signal processing unit 108 performs baseband signal processing on the radio signal input from the first radio unit 106 or the second radio unit 107, and has an external IF 109 having a user-side interface function. Output to. The external IF 109 corresponds to, for example, a microphone, a speaker, a display, and the like. Further, for example, when performing beam forming using four elements in the wireless communication system 10, the signal processing unit 108 performs beam forming using four elements on a WiFi transmission signal. Predetermined signal processing is executed, and the transmission signal after execution of the signal processing is output to the antenna control unit 105 via the second wireless IF unit 107.

  The GPS receiver 111 is a receiver that detects the GPS coordinates of the wireless terminal 11. The direction sensor 112 is a sensor that detects in which direction the opening surfaces of the antennas 101 to 104 of the wireless terminal 11 are directed. The gyro sensor 113 is a sensor that detects the yaw angle and pitching angle of the wireless terminal 11. The acceleration sensor 114 is a sensor that measures and outputs the acceleration (for example, the vertical direction, the horizontal direction, and the tilt direction) of the wireless terminal 11. The GPS receiver 111, the direction sensor 112, the gyro sensor 113, and the acceleration sensor 114 operate according to instructions from the terminal control unit 110 and output each output result to the terminal control unit 110.

  The terminal control unit 110 controls the functions of each unit of the wireless terminal 11 described above as a whole. Specifically, for example, the terminal control unit 110 aggregates the communication status in the selected radio communication system and the position information of the radio terminal 11, and the aggregated information is collected by the first radio base station 12 or the second radio base. The data is transmitted to the handover control unit 17 via the station 13. Further, for example, the terminal control unit 110 instructs switching of the wireless communication system to which the wireless terminal 11 is connected in accordance with the wireless communication system switching request notified from the handover control unit 17. In particular, when the handover control unit 17 is notified of a request to “select a WiFi system and execute beamforming”, the terminal control unit 110 transmits WiFi to the wireless communication system to which the wireless terminal 11 is connected. A method is selected, and the second wireless IF unit 107 is instructed to execute processing related to a WiFi wireless signal. Further, the terminal control unit 110 activates the GPS receiver 111, the direction sensor 112, the gyro sensor 113, and the acceleration sensor 114 to collect detection results, and the collected detection results and information notified from the handover control unit 17 are collected. Based on the position information of the included beam forming target (second radio base station 13), the beam target direction is determined in the direction in which the second radio base station 13 is estimated to exist, and the signal processing unit 108 Notify the decision result. Detailed processing in which the terminal control unit 110 determines the beam target direction will be described later with reference to FIG.

(1-1-4) Signal Processing Unit FIG. 4 is a block diagram showing the configuration of the signal processing unit shown in FIG. The signal processing unit 108 illustrated in FIG. 4 performs signal processing necessary when beamforming is performed by the wireless terminal 11, and includes an OFDM modulation unit 201, coefficient multiplication units 202 to 205, and a coefficient calculation unit 206.

  The OFDM modulation unit 201 performs modulation processing on transmission information input from the external IF 109 using an orthogonal frequency division multiplexing (OFDM) which is one of digital modulation methods.

  Based on the beam target direction information input from the terminal control unit 110, the coefficient calculation unit 206 performs coefficient forming so that the radio waves are strengthened in the beam target direction determined by the information. The coefficients given to 205 are respectively calculated. Specifically, the coefficient calculation unit 206 distributes the transmission signal transmitted from each of the four antenna elements to the coefficient multiplication units 202 to 205 from the external IF 109 so that the power and phase are the same in the beam target direction. Then, a coefficient for determining the amount of change in power and phase is calculated for each transmission signal input. The coefficients calculated by the coefficient calculation unit 206 are output to the coefficient multiplication units 202 to 205, respectively.

  The coefficient multipliers 202 to 205 generate power and phase for each transmission signal output to the antennas 101 to 104 via the second wireless IF unit 107 based on the coefficients calculated and input by the coefficient calculator 206. Process to change the value of. The transmission signal subjected to the power and phase value change processing based on the coefficients by the coefficient multiplication units 202 to 205 is subjected to modulation processing by the OFDM modulation unit 201, and the second radio IF unit 107 and the antenna control unit 105. Are transmitted from the antennas 101 to 104 via the. By executing such beam forming, the wireless terminal 11 can communicate with a second base station that is located farther away than when not performing beam forming.

(1-2) Processing by Radio Communication System Each process by the radio communication system 10 shown in FIG. 1 will be described below. Specifically, the beam target direction determination process will be described with reference to FIG. 5, and a series of processes for executing inter-system handover during communication in the 1 × EVDO system will be described with reference to FIGS. 6 to 8. A series of processes for executing inter-system handover during communication in the WiFi system will be described with reference to FIGS.

(1-2-1) Determination of Beam Target Direction First, the processing procedure in which the terminal control unit 110 determines the beam target direction for the beam target direction indicating the direction in which radio waves are transmitted when beam forming is executed will be described. FIG. 5 is a sequence diagram showing a processing procedure for determining the beam target direction.

  First, the terminal control unit 110 of the wireless terminal 11 acquires the position information of the second wireless base station 13 (step S101). The position information of the second radio base station 13 is managed by, for example, GPS coordinate information, and is obtained by referring to the AP position GPS coordinate column 1814 of the base station information table 181 stored in the position information server 18. For example, the wireless terminal 11 receives the information described in the base station information table 181 from the location information server 18 via the first wireless base station 12 or the second wireless base station 13 periodically. The position information of the two radio base stations 13 can be acquired.

  Next, the terminal control unit 110 starts a direction detection process for detecting the direction in which the second radio base station 13 is present (step S102). When the direction detection process in step S102 is started, the terminal control unit 110 transmits a position information request for requesting a report of position information indicating the position of the wireless terminal 11 to the GPS receiver 111 (step S103). A direction information request for requesting a report of the direction information indicating the direction of 11 is transmitted to the direction sensor 112 (step S104), and a camera shake information request for requesting a report of the shake information indicating the movement range of the wireless terminal 11 is transmitted to the gyro sensor. 113 (step S105), and transmits a body orientation information request for requesting a report of body orientation information indicating how much the wireless terminal 11 is tilted to the acceleration sensor 114 (step S106).

  The GPS receiver 111, the direction sensor 112, the gyro sensor 113, and the acceleration sensor 114 that have received each request transmitted in steps S103 to S106 acquire information according to each request (steps S107 to S113), and perform terminal control. Report to the unit 110 (step S117).

  The GPS receiver 111 that has received the position information request in step S103 receives the GPS signal (step S107), detects the GPS coordinate information of the wireless terminal 11 (step S108), and detects the detected GPS coordinate information of the wireless terminal 11. The position information is reported to the terminal control unit 110 (step S114).

  The azimuth sensor 112 that has received the azimuth information request in step S104 sets, for example, the direction perpendicular to the aperture plane of the array antenna (not shown) provided in the wireless terminal 11 as the reference of the azimuth sensor 112 and opens the array antenna aperture. The orientation of the surface is detected (step S109), and the detected orientation information is reported to the terminal control unit 110 as the orientation information of the wireless terminal 11 (step S415).

  In addition, the gyro sensor 113 that has received the camera shake information request in step S105 sets, for example, the direction perpendicular to the aperture surface of the array antenna provided in the wireless terminal 11 as the reference of the gyro sensor 113, and the yaw angle and the wireless terminal 11 The movement width of the pitching angle is detected, and this movement width is used as a parameter indicating the degree of camera shake in the vertical direction of the array antenna aperture, and is reported to the terminal control unit 110 as camera shake information of the wireless terminal 11 (step S416).

  The acceleration sensor 114 that has received the main body orientation information request in step S106 sets the reference of the acceleration sensor 114 with the long side direction on the aperture surface of the array antenna provided in the wireless terminal 11 as vertical and the short side direction as horizontal, for example. To do. Then, the acceleration sensor 114 detects whether the array antenna aperture of the wireless terminal 11 is vertical or horizontal (step S112), and further detects how much the inclination is (step S113). The detection results in step S112 and step S113 are reported to the terminal control unit 110 as main body orientation information of the wireless terminal 11 (step S117).

  Next, the terminal control unit 110 aggregates each information received in steps S114 to S117, calculates the moving speed of the wireless terminal 11 (step S118), and calculates the direction of the antenna opening surface of the wireless terminal 11 ( Step S119). Note that the orientation of the antenna opening surface in the wireless terminal 11 is indicated by using, for example, an angle and an azimuth formed by the vertical direction with respect to the antenna opening surface of the wireless terminal 11 as a parameter.

  Next, the terminal control unit 110 determines the position of the antenna opening surface of the wireless terminal 11 based on the position information of the second wireless base station 13 acquired in step S101 and the orientation of the antenna opening surface calculated in step S119. The current direction of the second radio base station 13 is calculated as to which direction the second radio base station 13 currently exists. Further, the terminal control unit 110 estimates the position of the future wireless terminal 11 based on the moving speed of the wireless terminal 11 calculated in step S118, and in which direction the second wireless base station exists from the estimated position. The predicted direction of the second radio base station 13 is calculated.

  Then, the terminal control unit 110 uses the calculated current direction or predicted direction of the second radio base station 13 as a beam target necessary when the radio terminal 11 performs beam forming toward the second radio base station 13. The direction is determined (step S120). Then, the terminal control unit 110 holds the determined beam target direction in the terminal control unit 110, and when the handover control unit 17 is instructed to execute beam forming for the second radio base station 13, the beam control unit 110 Send radio waves in the target direction. As a method of transmitting radio waves from the antennas 101 to 104 of the wireless terminal 11 in the beam target direction, for example, using the method described in FIG. Can be controlled.

  Note that the predicted direction of the second radio base station 13 in step S119 can be calculated by comparing the estimated position of the radio terminal 11 and the position of the second radio base station 13, but after a predetermined time has elapsed. The position information of the wireless terminal 11 may be re-acquired and calculated by taking into account the actual movement width and movement direction of the wireless terminal 11. Moreover, it is preferable that the process of determining the beam target direction is repeatedly executed every time the position information of the second radio base station 13 is acquired in step S101, and the terminal control unit 110 always maintains the latest beam target direction. By doing so, it is possible to reliably direct the direction in which radio waves are transmitted when beamforming is performed to the direction of the second radio base station 13 and to improve the probability of successful communication connection after beamforming.

  By executing the processing of steps S101 to S120 described above, the beam target direction in which the radio terminal 11 transmits radio waves when the beamforming is performed on the second radio base station 13 is determined. Note that the beam target direction determination process shown in steps S101 to S120 in FIG. 5 may be executed periodically, for example, and in this way, when there is a sudden change in the movement of the wireless terminal 11 In addition, the terminal control unit 110 can accurately determine the beam target direction.

(1-2-2) Processing from communication start to inter-system handover determination (during 1xEVDO system communication)
Next, processing by the wireless communication system 10 communicating with the 1xEVDO system will be described. FIG. 6 is a sequence diagram showing a processing flow from the start of communication by the 1xEVDO method to the determination of handover in the wireless communication system shown in FIG. Assume that the wireless terminal 11 is set to select a 1xEVDO wireless communication system when starting communication for the first time.

  First, the wireless terminal 11 determines the wireless communication system to be used as the 1xEVDO system and activates the 1xEVDO system (step S201). When the 1xEVDO system is activated in the wireless terminal 11, for example, the signal processing unit 108 and the terminal control unit 110 execute processing according to the 1xEVDO method.

  Next, the wireless terminal 11 connects to the first wireless base station 12 that is a 1xEVDO wireless base station, and performs a wireless connection setting process corresponding to a predetermined process for performing wireless communication. 12 (step S202). When the wireless connection setting process is completed, the wireless terminal 11 and the first wireless base station 12 start data communication with each other (step S203).

  After starting data communication in step S203, the wireless terminal 11 stores or updates the terminal communication status in an internal storage unit (not shown) (step S204). The terminal communication status here mainly indicates reception quality, communication speed, communication capacity, movement speed, traffic, and the like in the 1xEVDO system of the wireless terminal 11. In the wireless terminal 11, the terminal control unit 110 activates the GPS receiver 111. The terminal control unit 110 acquires GPS coordinates calculated based on the GPS signal received by the GPS receiver 111 as terminal position information indicating the position of the wireless terminal 11 (step S205). The terminal communication status and terminal location information are preferably acquired regularly or constantly and updated to the latest information.

  Next, the wireless terminal 11 executes a handover inquiry for inquiring of the handover control unit 17 whether or not to execute a handover (step S206). Specifically, the wireless terminal 11 uses the first wireless base station 12 and the first control network 14 as the latest terminal communication status acquired in step S204 and the terminal location information of the wireless terminal 11 acquired in step S205. Then, the handover control unit 17 is notified via the home agent 16 (step S207).

  The handover control unit 17 that has received the notification in step S207 acquires the terminal communication status and terminal location information of the wireless terminal 11 (step S208), and then determines intersystem handover in cooperation with the location information server 18 ( Step S209).

(1-2-3) Inter-system handover decision (at the time of 1xEVDO system communication)
FIG. 7 is a flowchart of a handover determination process procedure performed during communication by the 1xEVDO method in the wireless communication system shown in FIG. In steps S208 to S209 of FIG. 6, it has been described that the handover control unit 17 acquires the terminal communication status and the terminal location information and determines the inter-system handover while the wireless terminal 11 is communicating with the 1xEVDO system. Reference numeral 7 describes in detail the processing by the handover control unit 17. In the inter-system handover determination shown in FIG. 7, whether or not the inter-system handover to the WiFi system is executed in the radio communication system 10 communicating with the radio terminal 11 in the 1xEVDO system, and further, the inter-system handover to the WiFi system is performed. It is determined whether or not to perform beamforming when executing.

  First, when the wireless terminal 11 is communicating with the 1xEVDO system (step S301), the handover control unit 17 acquires the terminal communication status and terminal location information notified from the wireless terminal 11 (for example, step of FIG. 6). Corresponding to the processing of S208), the acquired information is stored in an internal storage unit (not shown) and updated (step S302).

  Based on the information acquired in step S302, the handover control unit 17 determines whether the communication status of the wireless terminal 11 is a communication status that should recommend a handover to the WiFi system (step S303). For example, when the communication quality in the current 1xEVDO system is good and a sufficient communication speed is obtained, the handover control unit 17 determines that it is not necessary to recommend a handover to the WiFi system. If the handover control unit 17 determines that it is not necessary to recommend handover to the WiFi system (NO in step S303), the handover control unit 17 continues communication in the 1xEVDO system.

  In step S303, for example, when the traffic in the current 1xEVDO system is in a high state exceeding a predetermined reference value, the handover control unit 17 determines that the communication status should recommend a handover to the WiFi system. To do. If the handover control unit 17 determines that the handover to the WiFi system should be recommended (YES in step S303), the handover control unit 17 proceeds to the process in step S304.

  In step S304, the handover control unit 17 refers to the base station information table 181 of the location information server 18. As described above in the description of the overall configuration of the wireless communication system 10, the location information server 18 is a database server for the WiFi system, and the base station information table 181 includes the second base station 13 that performs communication using the WiFi system. Information about is registered.

  Then, the handover control unit 17 sets the AP position GPS coordinates and the communicable GPS coordinates for each second wireless base station 13 described in the base station information table 181, the terminal position information of the wireless terminal 11 acquired in step S302, and Based on the above, it is determined whether the wireless terminal 11 is present in a network area provided by any of the second wireless base stations 13 (step S305). In step S305, only the second radio base station 13 (for example, AP001 and AP002 in FIG. 2) described as “in operation” in the service status column 1817 of the base station information table 181 is targeted.

  If the second radio base station 13 including the radio terminal 11 is present in the network area in step S305 (YES in step S305), the handover control unit 17 starts an intersystem handover to the WiFi system (step S305). S309). If the second radio base station 13 including the radio terminal 12 does not exist in the network area in step S305 (NO in step S305), the handover control unit 17 proceeds to the process in step S306.

  In step S306, the handover control unit 17 refers to the beamforming possible range GPS coordinates in the base station information table 181 and sets the beamforming network area provided by the second radio base station 13 when beamforming is executed. It is determined whether the wireless terminal 11 exists.

  If the second radio base station 13 including the radio terminal 11 does not exist in the beam forming network area in step S306 (NO in step S306), the handover control unit 17 cannot execute the handover to the WiFi system. Determine and continue communication with the 1xEVDO system. If the second radio base station 13 including the radio terminal 11 exists in the beam forming network area in step S306 (YES in step S306), the handover control unit 17 executes a handover to the WiFi system. It judges that it is possible, and progresses to the process of step S307.

  In step S307, the handover control unit 17 transmits the AP position GPS coordinates (AP position information) of the second radio base station 13 selected in step S306 to the radio terminal 11, and the second radio base station 11 receives the second location. Is instructed to execute beam forming toward the GPS coordinates indicated by the AP position information of the wireless base station 13. The wireless terminal 11 calculates the beam target direction as described with reference to FIG. 5 using the AP position GPS coordinates of the second wireless base station 13 received from the handover control unit 17 as a trigger, and sets the calculated beam target direction to the calculated beam target direction. Transmitting radio waves for beam forming

  Then, the handover control unit 17 transmits the terminal position information of the wireless terminal 11 to the second wireless base station 13 selected in step S306, and the terminal position of the wireless terminal 11 is transmitted to the second wireless base station 13. An instruction is given to execute beam forming toward the GPS coordinates indicated by the information (step S308). The second radio base station 13 determines a beam target direction to the radio terminal 11 based on its own GPS coordinates and the terminal position coordinates of the radio terminal 11, and transmits a beam forming radio wave in the determined beam target direction. send. As for the method in which the second radio base station 13 transmits radio waves in the beam target direction to the radio terminal 11, the second radio base station 13 uses the generally used radio wave transmission direction control method. What is necessary is just to control the transmission direction of an electromagnetic wave by internal processing.

  Since beam forming is executed by the processing of step S307 and step S308, the wireless terminal 11 is present in the network area of the second wireless base station 13, so that the handover control unit 17 connects to the WiFi system. A handover is started (step S309). If the second radio base station 13 including the radio terminal 11 exists in the network area in step S305, the radio terminal 11 can communicate with the second radio base station 13 without performing beamforming. Therefore, the handover control unit 17 starts the inter-system handover to the WiFi system without performing the processes in steps S307 and S308.

(1-2-4) Inter-system Handover Processing to WiFi System FIG. 8 is a flowchart showing a processing procedure for inter-system handover to the WiFi system. FIG. 8 illustrates the inter-system handover process performed in steps S307 to S309 when YES is determined in step 306 in FIG. 7, that is, a process procedure for performing inter-system handover to the WiFi system by executing beamforming. ing.

  First, the handover control unit 17 requests the wireless terminal 11 to start an intersystem handover to the WiFi system via the home agent 16, the first control network 14, and the first wireless base station 12. Request for handover to "is transmitted (step S401). The wireless terminal 11 that has received the “handover request to WiFi” activates the WiFi system in accordance with the request (step S402). When the WiFi system is activated in the wireless terminal 11, for example, the signal processing unit 108 and the terminal control unit 110 execute processing according to the WiFi scheme.

  Next, the handover control unit 17 notifies the wireless terminal 11 of the AP position information of the second wireless base station 13 that performs beam forming (step S403). The wireless terminal 11 receives the AP position information and acquires the position information of the second wireless base station 13 that is the target of beam forming (step S404). Then, the wireless terminal 11 starts beam forming toward the GPS coordinates indicated by the position information of the second wireless base station 13 acquired in step S404 (step S405). The processing in steps S403 to S405 in FIG. 8 corresponds to the processing in step S307 in FIG. 7, and the beam target direction for performing the beam forming is determined by the processing described above with reference to FIG.

  Further, the handover control unit 17 notifies the terminal position information of the wireless terminal 11 to the second wireless base station 13 that performs beamforming (step S406). The second radio base station 13 receives the terminal location information and acquires the location information of the radio terminal 11 (step S407). Then, the second radio base station 13 starts beam forming toward the GPS coordinates indicated by the position information of the radio terminal 11 acquired in step S407 (step S408). The processing in steps S406 to S408 in FIG. 8 corresponds to the processing in step S308 in FIG.

  When both the processing of step S405 and the processing of S408 are completed, a wireless connection setting process corresponding to a predetermined process for performing wireless communication is executed between the wireless terminal 11 and the second wireless base station 13. (Step S409). When the wireless connection setting process is completed, the wireless terminal 11 and the second wireless base station 13 start data communication with each other (step S410).

  The inter-system handover from the 1xEVDO system to the WiFi system is completed by the processes in steps S401 to S410. When the inter-system handover is completed, the wireless terminal 11 does not need to be connected to the first wireless base station 12 that is a wireless base station for 1xEVDO. Thus, a wireless disconnection process corresponding to a predetermined process for terminating the wireless communication is executed (step S411). Then, the wireless terminal 11 stops the 1xEVDO system (step S412).

  By performing the processing of each step shown in FIGS. 6 to 8 described above, the wireless communication system 10 causes the wireless terminal 11 to perform the second communication while the wireless terminal 11 is communicating with the 1xEVDO system that is the first communication method. If it is a situation that can be handed over to the WiFi system, which is a communication method, assuming the network area at the time of beam forming, and if it is a situation that can be handed over, execute beam forming if necessary, By executing the inter-system handover, the connection destination of the wireless terminal 11 can be actively switched to the wireless base station 13 of the second communication method.

(1-2-5) Inter-system Handover Processing to 1xEVDO System Next, processing by the wireless communication system 10 communicating with the WiFi system will be described. FIG. 9 is a sequence diagram showing a flow of processing for performing inter-system handover from the WiFi system to the 1xEVDO system in the wireless communication system shown in FIG. In the start state of FIG. 9, the wireless terminal 11 starts the WiFi system and connects to the second wireless base station 13 to perform data communication by the WiFi method.

  First, the wireless terminal 11 performing data communication using the WiFi method acquires the terminal communication status and terminal location information, and stores or updates the information in the storage unit (step S501). The terminal communication status here mainly indicates reception quality, communication speed, communication capacity, moving speed, traffic, and the like in the WiFi system of the wireless terminal 11. The terminal position information is GPS coordinates obtained when the terminal control unit 110 activates the GPS receiver 111. The terminal communication status and terminal location information are preferably acquired regularly or constantly and updated to the latest information.

  Next, the wireless terminal 11 executes a handover inquiry that inquires of the handover control unit 17 whether or not to execute a handover (step S502). Specifically, the radio terminal 11 performs handover control on the latest terminal communication status and terminal location information acquired in step S501 via the second radio base station 13, the second control network 15, and the home agent 16. The unit 17 is notified (step S503).

  The handover control unit 17 that has received the notification in step S503 acquires the terminal communication status and terminal location information of the wireless terminal 11 (step S504), and then determines inter-system handover in cooperation with the location information server 18 (step S504). Step S505).

  A detailed process in which the handover control unit 17 acquires the terminal communication status and the terminal location information and determines the inter-system handover in steps S504 to S505 will be described later with reference to FIG. In the following, the description of the processing is continued when the handover control unit 17 determines in step S505 that an inter-system handover to the 1xEVDO system is to be executed.

  The handover control unit 17 that has determined that the inter-system handover to the 1xEVDO system in step S505 is to be performed is sent to the wireless terminal 11 via the home agent 16, the second control network 15, and the second wireless base station 13, and 1xEVDO. A “handover request to 1xEVDO” requesting the start of the inter-system handover to the system is transmitted (step S506). The wireless terminal 11 that has received the “handover request to 1xEVDO” activates the 1xEVDO system in accordance with the request (step S507). When the 1xEVDO system is activated in the wireless terminal 11, for example, the signal processing unit 108 and the terminal control unit 110 execute processing according to the 1xEVDO method.

  Next, the wireless terminal 11 searches for a wireless base station for 1xEVDO and discovers the first wireless base station 12 in order to perform wireless communication using the 1xEVDO method (step S508). Thereafter, a wireless connection setting process corresponding to a predetermined process for performing wireless communication is performed between the wireless terminal 11 and the first wireless base station 12 (step S509). When the wireless connection setting process is completed, the wireless terminal 11 and the first wireless base station 12 start data communication with each other (step S510).

  The inter-system handover from the WiFi system to the 1xEVDO system is completed by the processes in steps S507 to S510. When the inter-system handover is completed, the wireless terminal 11 does not need to be connected to the second wireless base station 13 which is a wireless base station for WiFi, so that the wireless terminal 11 is not connected between the wireless terminal 11 and the second wireless base station 13. Thus, a wireless connection disconnection process corresponding to a predetermined process for ending the wireless communication is executed (step S511). Then, the wireless terminal 11 stops the WiFi system (step S512).

(1-2-6) Determination of handover (during WiFi system communication)
FIG. 10 is a flowchart of a handover determination process procedure performed at the time of communication using the WiFi scheme in the wireless communication system illustrated in FIG. In the handover determination shown in FIG. 10, in the wireless communication system 10 that is communicating with the wireless terminal 11 in the WiFi system, whether the inter-system handover to the 1xEVDO system is executed under the policy of continuing the communication by the WiFi system as much as possible. It is determined whether or not. Hereinafter, specific processing will be described.

  First, when the wireless terminal 11 is communicating with the WiFi system (step S601), the handover control unit 17 acquires the terminal communication status and the terminal location information notified from the wireless terminal 11 (for example, FIG. 9). Corresponding to the processing in step S504), the acquired information is stored in an internal storage unit (not shown) and updated (step S602).

  Based on the information acquired in step S602, the handover control unit 17 determines whether the communication status of the wireless terminal 11 is a communication status that should recommend a handover (step S603). For example, when the communication quality in the current WiFi system is good and a sufficient communication speed is obtained, the handover control unit 17 determines that the handover need not be recommended. If the handover control unit 17 determines that it is not necessary to recommend a handover (NO in step S603), the handover control unit 17 continues communication in the WiFi system.

  In step S603, for example, the wireless terminal 11 moves from the time when it was handed over to the WiFi system in the past, so that the reception quality in the current WiFi system falls below a predetermined reference value and the communication speed is not sufficient. In some cases, the handover control unit 17 performs the process of step S604 in order to determine whether or not handover is possible in the WiFi system.

  In step S604, the handover control unit 17 refers to the base station information table 181 of the location information server 18. As described above in the description of the overall configuration of the wireless communication system 10, the location information server 18 is a database server for the WiFi system, and the base station information table 181 includes the second base station 13 that performs communication using the WiFi system. Information about is registered.

  Then, the handover control unit 17 is based on the SSID, the AP position GPS coordinates, the communicable range GPS coordinates, and the service state described in the base station information table 181 and the terminal position information of the wireless terminal 11 acquired in step S602. In the vicinity of the second radio base station 13 (for example, AP001 in FIG. 2) currently communicating with the radio terminal 11, another second radio base station 13 (including the radio terminal 11 in the network area) ( For example, it is determined whether AP002 in FIG. 2 exists (step S605).

  If there is another second radio base station 13 including the radio terminal 11 in the network area in step S605 (YES in step S605), the handover control unit 17 determines that the other second radio base station 13 Intra-system handover to is started (step S609). When the intra-system handover is executed in step S609, the communication connection destination of the radio terminal 11 is switched to the other second radio base station 13 while the WiFi system is selected as the communication system.

  If no other second radio base station 13 including the radio terminal 11 is present in the network area in step S605 (NO in step S605), the handover control unit 17 performs the WiFi system if beamforming is performed. In order to determine whether or not the communication by can be maintained, the process of step S606 is performed.

  In step S606, the handover control unit 17 refers to the beam forming possible range GPS coordinates described in the base station information table 181 in addition to the information referred to in step S605, and performs wireless communication within the range of the network area during beam forming. It is determined whether there is another second radio base station 13 including the terminal 11.

  In step S606, when there is another second radio base station 13 including the radio terminal 11 in the beam forming network area (YES in step S606), the handover control unit 17 performs the beamforming. It is determined that the communication by the WiFi system can be maintained, and the process proceeds to step S607.

  In step S607, the handover control unit 17 transmits the AP position information of the second radio base station 13 selected in step S606 to the radio terminal 11, and the radio terminal 11 receives the second radio base station 13's AP location information. An instruction is given to execute beam forming toward the GPS coordinates indicated by the AP position information. The radio terminal 11 calculates the beam target direction as described with reference to FIG. 5 using the AP position information of the second radio base station 13 received from the handover control unit 17 as a trigger, and directs it toward the calculated beam target direction. Radio waves for beam forming.

  Then, the handover control unit 17 transmits the terminal position information of the wireless terminal 11 to the second wireless base station 13 selected in step S606, and the terminal position of the wireless terminal 11 is transmitted to the second wireless base station 13. An instruction is given to execute beam forming toward the GPS coordinates indicated by the information (step S608). The second radio base station 13 determines a beam target direction to the radio terminal 11 based on its own GPS coordinates and the terminal position coordinates of the radio terminal 11, and transmits a beam forming radio wave in the determined beam target direction. send.

  Since the beam forming is executed by the processing in step S607 and step S608, the wireless terminal 11 is present in the network area of the other second wireless base station 13 selected in step S606. The unit 17 starts an intra-system handover for switching the communication connection destination of the wireless terminal 11 from the current second wireless base station 13 to the other second wireless base station 13 selected in Step S606 (Step S609). . When the intra-system handover is executed in step S609, the communication connection destination of the radio terminal 11 is switched to the other second radio base station 13 while the WiFi system is selected as the communication system.

  On the other hand, in step S606, when the wireless terminal 11 is not included in the range of the network area during beam forming by the other second radio base station 13 (NO in step S606), the handover control unit 17 performs the beam forming. Even if the communication is performed, it is determined that the communication by the WiFi system cannot be maintained, and the inter-system handover to the 1xEVDO system is started (step S610). The processing after the inter-system handover is started in step S610 is shown in the processing in steps S506 to S512 in FIG. When the inter-system handover is completed, the communication connection destination of the wireless terminal 11 is switched from the second wireless base station 13 of the WiFi system to the first wireless base station 12 of the 1xEVDO system.

  By performing the processing of each step shown in FIG. 9 to FIG. 10, the wireless communication system 10 allows the second communication method as much as possible while the wireless terminal 11 is communicating with the WiFi system that is the second communication method. Under the policy of maintaining communication according to the above, it is determined whether it is necessary to execute intra-system handover or inter-system handover based on the communication status. Specifically, when the communication quality is deteriorated, if the wireless terminal 11 is within the network area by the other second wireless base station 13 or the network area during beam forming, the intra-system handover is executed. Then, the connection destination of the wireless terminal 11 is switched to the other second wireless base station 13 to maintain communication by the second communication method. Then, only when the connection destination cannot be switched to the other second radio base station 13, the inter-system handover is executed to switch the connection destination of the radio terminal 11 to the first radio base station 12, and the first communication Communicate by the method.

(1-3) Network Area by Beam Forming As described above, the wireless communication system 10 according to the present embodiment is a process that actively switches the communication method used by the wireless terminal 11 to the second communication method. If necessary, beam forming is executed to expand the network area, and then an inter-system handover is executed. Hereinafter, a change in the network area at the time of executing beamforming and a frame of a signal transmitted / received at the time of executing beamforming will be described with reference to FIGS.

  FIG. 11 is an image diagram showing changes in the network area due to execution of beamforming. The network area 100A is a network area provided by the second radio base station 13 during normal times when beam forming is not being performed. The network area 100B is a network area (a network at the time of beam forming) provided by the second radio base station 13 to be expanded by beam forming when beam forming is executed between the radio terminal 11E and the second radio base station 13. Area).

  As shown in FIG. 11, terminals that can communicate with the second radio base station 13 at normal times are the radio terminals 11A to 11D, and the radio terminal 11E existing outside the network area 100A is the second radio base station. 13 can not communicate. Then, when the second radio base station 13 performs beam forming and the network area 100B is expanded around the radio terminal 11E, the radio terminal 11E can communicate with the second radio base station 13.

  However, if the second radio base station 13 always performs beamforming with the radio terminal 11E, the second radio base station 13 provides only the network area 100B, and the radio terminals 11A to 11A to 11D cannot communicate with the second radio base station 13 because it does not exist within the network area 100B. In general, since the radio base station is required to be able to perform radio communication with a plurality of radio terminals, even if the second radio base station 13 can expand the network area and communicate with the radio terminal 11E. It is not preferable that communication with the other wireless terminals 11A to 11D becomes impossible.

  Therefore, in the radio communication system 10 according to the present embodiment, the second radio base station 13 can execute beam forming with the radio terminal 11E without affecting communication with the other radio terminals 11A to 11D. As described above, transmission / reception is performed using a signal including a slot frame as illustrated in FIG.

  FIG. 12 is a configuration example of a slot frame of a signal transmitted / received by a radio base station that is executing beamforming. The slot frame shown in FIG. 12 is a slot frame based on a time division duplex (TDD) system. The TDD system uses the same frequency for uplink (reception) and downlink (transmission), separates uplink communication and downlink communication on the time axis, and switches the communication direction at high speed in a short cycle. This is a method for realizing bidirectional communication. A plurality of resources allocated by dividing a predetermined frequency band are mounted on the time-divided frame.

  In FIG. 12, the frequency is shown in the vertical direction and the time is shown in the horizontal direction. The downlink subframe 1311 indicates a frame that communicates in the downlink direction (at the time of transmission), and the uplink subframe 1313 indicates a frame that communicates in the uplink direction (at the time of reception). A TG (Transition Gap) 1312 indicates a gap at the time of transmission / reception switching. A time-divided frame (corresponding to each column in FIG. 12) is represented by an aggregate of resources 1314. Further, “AT1” to “AT5” described in each resource 1314 indicate destinations of the resource 1314, and “AT1” to “AT5” correspond to the wireless terminals 11A to 11E in FIG. 11, respectively. .

  Here, the configuration of the signal transmitted by the second radio base station 13 that is executing beamforming will be described in detail. In the present embodiment, the second radio base station 13 transmits and receives a slot frame obtained by time-dividing a frame for a radio terminal that is a target of beam forming and a frame for a radio terminal that is not a target of beam forming. Features.

  A specific description will be given by taking the downlink subframe 1311 of FIG. 12 as an example. First, the wireless terminal to be beam-formed is the wireless terminal 11E existing in the network area 100B shown in FIG. 9, that is, “AT5”. As shown in the fourth column from the left of the downlink subframe 1311, the second radio base station 13 transmits the resource 1315 destined for “AT5” in a frame of the same time, and at this time, the radio terminal 11E Perform beamforming for. The wireless terminals that are not subject to beam forming are the wireless terminals 11A to 11D existing in the network area 100A shown in FIG. 9, that is, “AT1” to “AT4”. As shown in the first to third columns or the fifth to seventh columns from the left of the downlink subframe 1311, the second radio base station 13 collects resources 1314 destined for “AT1” to “AT4” in a frame. Send. At this time, the second radio base station 13 does not perform beam forming.

  Although only the details of the downlink subframe 1311 are shown in FIG. 12, the same applies to the uplink subframe 1313, and the second radio base station 13 includes a frame from the radio terminal 11E to be beam-formed, A slot frame in which frames from radio terminals 11A to 11D that are not subject to beam forming are time-divided is received. Then, the second radio base station 13 performs beam forming for the radio terminal 11E only when receiving a frame from the radio terminal to be beam-formed.

  In this way, when the second radio base station 13 does not perform beam forming by handling the frame that performs communication by performing beam forming and the frame that performs communication without performing beam forming in a time-sharing manner, While maintaining communication with the wireless terminals 11A to 11D existing in the network area, communication can be realized in the extended network area by performing beam forming only when communicating with the wireless terminal 11E.

  In a series of subframes, when the ratio of frames transmitted and received by performing beamforming is high, the time during which network area 100B is provided by execution of beamforming increases, and network area 100A at normal time is provided. Therefore, there is a possibility that the stability of communication by the network area 100A is lowered. Therefore, the second radio base station 13 preferably suppresses the ratio of including the frames to be transmitted / received by executing beamforming in the subframes so as not to affect the communication by the network area 100A at the normal time. For example, in the radio communication system 10 having the time slot configuration as shown in FIG. 12, when scheduling is performed so that resources are almost equally allocated to all the radio terminals 11 to 11E, the number of time slots allocated to the beamforming frame 1315 is 1 slot.

(1-4) Effects According to this Embodiment According to such a wireless communication system 10, the handover control unit 17 uses the second communication method for the wireless terminal 11 communicating with the first communication method. Whether or not handover is possible is determined in consideration of not only the network area normally provided from the second radio base station 13 but also the network area provided by extension during execution of the beamforming, and the second Since control is performed so as to preferentially select the communication method, it is possible to prevent communication from being concentrated on the first communication method, and to expand the network area provided by the second communication method and connect with priority. Can do.

  Further, according to such a wireless communication system 10, the slot frame of the signal transmitted / received by the second wireless base station 13 during execution of beamforming includes the frame for the wireless terminal 11E to be subjected to beamforming, Since the frames for the wireless terminals 11A to 11D that are not the target are configured in a time-sharing manner, the wireless terminal 11A to 11D can perform communication using the normal second communication method that does not perform beam forming, and the wireless terminal With 11E, communication by the second communication method in which beam forming is executed can be realized. As a result, there is an effect that the wireless terminals 11A to 11E are equally provided with the communication service by the second communication method.

  In addition, according to such a wireless communication system 10, the handover control unit 17 also allows other second wireless base stations to be connected even when the communication state becomes worse while the wireless terminal 11 is communicating with the second communication method. Since the second communication method is maintained as much as possible by searching the network area provided by the wireless communication device 13, the first communication method is used in the entire wireless communication system 10 that performs wireless communication with the plurality of wireless terminals 11. It is possible to prevent the access from being concentrated on the wireless communication by the wireless communication and to continue the wireless communication by the second communication method with priority.

(2) Other Embodiments In the wireless communication system 10 according to the above-described embodiment, the case where the first communication method is the 1xEVDO method has been described. However, the present invention is not limited to this, for example, 3GGP. A wireless communication system compliant with the standard may be used. The second communication method is not limited to the WiFi method, and may be a wireless LAN communication method that has not received WiFi authentication, for example. Furthermore, various communication methods generally used for wireless communication such as data and voice can be applied to the first and second communication methods, but the second communication method is more suitable than the first communication method. It is preferable that the communication method is for a shorter distance, in other words, the network area provided by the wireless base station in the first communication method is more than the network area provided by the wireless base station in the second communication method. The wider one is preferable.

  Further, in the wireless communication system 10 according to the above-described embodiment, the wireless terminal 11 performs internal processing to transmit a beam forming radio wave in the beam target direction when performing beam forming. The present invention is not limited to this. For example, the direction of the antenna opening surface of the wireless terminal 11 is changed by three-dimensionally displaying the beam target direction on a display unit (not shown) of the wireless terminal 11. It may be configured to prompt the user of the wireless terminal 11. In such a case, if the user changes the direction of the antenna opening surface of the wireless terminal 11 in the beam target direction, the deviation between the direction of the antenna opening surface of the wireless terminal 11 and the beam target direction is reduced. Therefore, it is possible to reduce the processing for correcting and controlling the transmission direction of the radio wave transmitted from the station, and as a result, it can be expected that the beam forming is performed more reliably.

  In the wireless communication system 10 according to the above-described embodiment, the handover control unit 17 transmits the terminal location information of the wireless terminal 11 to the second wireless base station 13 in step S308 in FIG. 7 and step S608 in FIG. The case where the second radio base station 13 is instructed to perform beam forming toward the GPS coordinates indicated by the terminal position information of the radio terminal 11 has been described. However, the present invention is not limited to this, and the handover control unit 17 may be configured to notify the second radio base station 13 of the beam target direction to the radio terminal 11 and instruct execution of beam forming. More specifically, for example, in step S307 of FIG. 7, the radio terminal 11 notifies the handover control unit 17 of the calculated beam target direction to the second radio base station 13. In step S308, the handover control unit 17 may notify the second radio base station 13 of the beam target direction to the radio terminal 11 as the beam target direction reversed by 180 degrees. In such a case, the second radio base station 13 can acquire the beam target direction for the radio terminal 11 without receiving the GPS coordinates of the radio terminal 11.

  Moreover, in the radio | wireless communications system 10 by one Embodiment mentioned above, although the case where the signal which the 2nd radio | wireless base station 13 transmits / receives was a TDD system was described, this invention is not limited to this, For example, a frequency band is used. You may comprise so that the frequency division duplex (FDD: Frequency Division Duplex) system which divides | segments into transmission and reception and performs simultaneous transmission / reception may be used. When the signal transmitted / received by the second radio base station 13 is the FDD system, the second radio base station 13 synchronizes transmission / reception and executes beam forming at a predetermined transmission / reception timing to perform transmission / reception. And a frame to be transmitted / received in accordance with the timing may be time-divided and inserted into the slot frame. A wireless communication system configured in this manner performs communication with a wireless terminal that does not require beamforming, and performs beamforming. Necessary wireless terminal communication can be realized in parallel.

  Moreover, in the radio | wireless communications system 10 by one Embodiment mentioned above, although the case where the radio | wireless terminal 11 and the 2nd radio | wireless base station 13 can perform beam forming toward each other was described, this invention is not limited to this, For example, either the wireless terminal 11 or the second wireless base station 13 may be configured to perform beam forming toward the other. In such a case, the expandable network area is narrower than the case where the radio terminal 11 and the second radio base station 13 execute beam forming with each other, but the processing amount on the side where the beam forming is not executed is reduced. can do.

DESCRIPTION OF SYMBOLS 10 Radio | wireless communications system 11 (11A-11E) Radio | wireless terminal 12 1st radio base station 13 2nd radio base station 14 1st control network 15 2nd control network 16 Home agent 17 Handover control part 18 Location information server 101 ˜104 antenna 105 antenna control unit 108 signal processing unit 110 terminal control unit 111 GPS receiver 112 direction sensor 113 gyro sensor 114 acceleration sensor

Claims (10)

In a wireless communication system capable of wireless communication with a plurality of different communication methods,
A first radio base station that provides a network area corresponding to the first communication method;
A second radio base station that provides a network area corresponding to the second communication method;
A first communication system for performing wireless communication with the first wireless base station by the first communication method and a second for performing wireless communication with the second wireless base station by the second communication method. A wireless terminal having the communication system of
A location information server that acquires and stores base station information related to the second radio base station from the second radio base station;
Based on the terminal location information indicating the location of the wireless terminal and the base station information stored in the location information server, the communication method used by the wireless terminal is preferentially selected. And a handover control unit for controlling
The base station information includes information indicating a first network area that can be provided when the second radio base station does not perform beamforming, and is expanded when the second radio base station performs beamforming. Information indicating a second network area that can be provided, and
The handover controller is
If the wireless terminal communicating with the first communication method exists in the first network area, it is determined to switch to the second communication method,
Even if the wireless terminal communicating with the first communication method does not exist in the first network area, but does not exist in the second network area, the second wireless base station Determining to switch to the second communication method after performing beam forming for the wireless terminal,
If the handover control unit decides to switch to the second communication method, the handover control unit performs a handover and moves the radio base station to which the radio terminal communicates from the first radio base station to the second radio system. A radio communication system characterized by switching to a base station. The second radio base station, when performing beam forming, communicates with the radio terminal that is the target of beam forming, and the other radio terminal that is time-divided into the frame and is not subject to the beam forming. The wireless communication system according to claim 1, wherein a slot frame composed of a frame communicating with the wireless communication device is transmitted and received. The handover controller is
If the wireless terminal that is communicating with the first communication method does not exist in the first network area but does exist in the second network area, the wireless terminal and the second The radio communication system according to claim 1, wherein both the radio base station and the radio base station are determined to switch to the second communication method after performing beamforming in the mutual direction. The wireless communication system includes a plurality of the second wireless base stations,
When communication quality deteriorates during communication between the wireless terminal and the second wireless base station,
The handover controller is
When the wireless terminal exists in a third network area that can be provided by performing beam forming by another second wireless base station, the other second wireless base station is connected to the wireless terminal with respect to the second wireless base station. After performing beamforming, perform handover to switch the communication destination of the wireless terminal to the other second wireless base station,
The wireless communication according to claim 1, wherein when the wireless terminal does not exist in the third network area, handover is performed to switch a communication destination of the wireless terminal to the first wireless base station. system. The wireless communication system according to claim 1, wherein the first wireless base station provides a network area wider than a network area provided by the second wireless base station. A wireless communication control method for controlling a communication method used by the wireless terminal in a wireless communication system capable of wireless communication with a plurality of different communication methods,
The wireless communication system includes:
A first radio base station that provides a network area corresponding to the first communication method;
A second radio base station that provides a network area corresponding to the second communication method;
A first communication system for performing wireless communication with the first wireless base station by the first communication method and a second for performing wireless communication with the second wireless base station by the second communication method. A wireless terminal having the communication system of
A location information server that acquires and stores base station information related to the second radio base station from the second radio base station;
Based on the terminal location information indicating the location of the wireless terminal and the base station information stored in the location information server, the communication method used by the wireless terminal is preferentially selected. A handover control unit for controlling
The base station information includes information indicating a first network area that can be provided when the second radio base station does not perform beamforming, and is expanded when the second radio base station performs beamforming. Information indicating a second network area that can be provided, and
A first step in which the handover control unit determines to switch to the second communication method when the wireless terminal in communication with the first communication method exists in the first network area;
When the handover control unit is present in the second network area even when the wireless terminal in communication with the first communication method does not exist in the first network area, A second step of deciding to switch to the second communication method after causing the second radio base station to perform beam forming for the radio terminal;
When the handover control unit decides to switch to the second communication method, the handover is performed, and the radio base station that is the communication destination of the radio terminal is moved from the first radio base station to the second radio system. And a third step of switching to a base station. A wireless communication control method comprising: When the second radio base station performs beam forming, the frame that communicates with the radio terminal that is the target of the beam forming, and the other radio terminal that is time-divided into the frame and that is not the target of the beam forming The wireless communication control method according to claim 6, further comprising: transmitting and receiving a slot frame including a frame communicating with the wireless communication device. In the second step, the handover control unit causes the second network area to be in the second network area even when the wireless terminal in communication with the first communication method does not exist in the first network area. If it exists, it is determined that both the radio terminal and the second radio base station perform beamforming in the direction of each other and then switch to the second communication method. A wireless communication control method according to claim 6. The wireless communication system includes a plurality of the second wireless base stations;
When communication quality deteriorates during communication between the wireless terminal and the second wireless base station,
When the wireless terminal exists in a third network area that can be provided by the handover control unit performing beamforming by another second radio base station, the other second radio base station The station is caused to perform beam forming for the wireless terminal, and then performs handover to switch the communication destination of the wireless terminal to the other second wireless base station, and the wireless terminal is located in the third network area. The wireless communication control method according to claim 6, further comprising a fourth step of performing handover and switching the communication destination of the wireless terminal to the first wireless base station when the wireless terminal does not exist. The radio communication control method according to claim 6, wherein the first radio base station provides a network area wider than a network area provided by the second radio base station.

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