JP2010239657A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system that determines the cell of a handover destination and executes handover. <P>SOLUTION: A handover control server 3 calculates a weight function for a peripheral cell, based on network constituent information, cell constituent information, radio access capability of a mobile unit and used resources, on a cell basis measured by base stations 2-1 to 2-3; annunciates a cell list wherein weight function information with the calculated weight function and a weight function identifier paired, and information related to the weight function identifier of the peripheral cell, a base station for controlling the peripheral cell, a radio access method of the base station, an edge router for housing the base station and a router for identifying the edge router are registered, in association with the peripheral cell generated based on the weight function information, the network constituent information and the cell constituent information; and determines the cell of a handover destination by calculating a peripheral cell selection parameter by measuring radio line quality of a peripheral cell, where the mobile unit 1 is registered in the cell list and a cell which is currently connected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication system, and more particularly to a handover in a wireless communication system.

  Conventionally, various techniques related to a handover method in a wireless communication system have been considered. As a handover method using radio channel quality as a condition for selecting a cell to be handed over by a mobile device, there are a method in which the mobile device selects a cell to be handed over and a method in which a base station control device selects a cell to be handed over.

  In the method in which a mobile station selects a cell to be handed over, if the radio channel quality of the cell being communicated deteriorates, the mobile station obtains a handover candidate destination cell (cells in the vicinity of the cell being communicated) previously acquired by broadcast information. Measure the radio channel quality, select the cell with the best radio channel quality among the measured radio channel quality, and set the selected cell and radio channel to improve the radio channel quality from the cell with degraded radio channel quality Hand over to the cell.

  In the method of selecting a cell to be handed over by the base station controller, if the radio channel quality of the cell being communicated deteriorates, the mobile station obtains a handover candidate destination cell (cells in the vicinity of the cell being communicated) previously acquired by broadcast information. ) Is measured and notified to the base station controller, and the base station controller selects the cell with the best radio channel quality among the reported radio channel qualities of each cell, and selects the selected cell. The radio resources of the base station to be controlled are secured and the mobile station is instructed to perform handover to the selected cell. The mobile station determines the radio channel quality from the cell whose radio channel quality has deteriorated according to the instruction from the base station controller. Hand over to a good cell.

  Further, for example, Patent Documents 1 and 2 are conventional techniques for selecting a cell to be handed over in consideration of not only wireless channel quality but also other conditions. In Patent Literature 1, a radio base station (base station) that controls a handover candidate cell of a mobile station (mobile device) reports the number of mobile devices that can be accepted by the own station (number of acceptable mobile stations), The mobile station that has received the broadcast information determines the radio channel quality from the reception level of the broadcast information, and selects the base station having the reception level that is greater than or equal to a predetermined value and the largest number of mobile stations that can be accepted as the connection destination. Technology is disclosed.

  Specifically, each radio base station has a total communication resource amount and a predetermined unit communication resource amount (a value depending on a communication environment assumed for the system, a minimum communication speed, and communication quality). The number of mobile stations that can be accepted is calculated based on the number of mobile stations that the local station is currently connected to, and a notification signal including the calculated number of mobile stations that can be accepted is transmitted at a constant period.

  The mobile station extracts the number of mobile stations that can be accepted included in the broadcast signal when the reception level of the broadcast signal from each neighboring radio base station that can be a connection destination candidate is equal to or higher than a predetermined reception level. The mobile station selects the radio base station having the maximum value as the connection target radio base station among the extracted number of acceptable mobile stations. Here, when there are a plurality of radio base stations having the maximum value, a radio base station having the maximum broadcast signal reception level is selected as a connection-destination radio base station among the radio base stations having the maximum value.

  Patent Document 2 discloses a technique for notifying a usable radio resource amount and selecting a handover candidate cell. Specifically, each radio base station (base station) periodically transmits a beacon signal, and the radio resource management device identifies an identifier of the radio base station existing around the mobile terminal device (mobile device), and the radio base A radio base station information advertisement message including the radio base station information of the station is periodically notified to the mobile terminal apparatus.

  When the mobile terminal apparatus detects from the beacon signal and the radio base station information advertisement message from each radio base station that there is a radio base station whose reception state is sufficiently better than the radio base station in communication, A detected radio base station notification message including an identifier, communication quality information with these radio base stations, and information on the amount of resources required by the own apparatus is transmitted to the radio resource management apparatus.

  When the radio resource management device receives the detected radio base station notification message, the radio resource management device acquires information from the detected radio base station notification message, radio resource information of each radio base station, billing information when using each radio base station, A radio base station that is a destination candidate is selected based on information about access authority of each mobile terminal device to each radio base station.

  The radio resource management apparatus transmits to the mobile terminal apparatus a destination candidate radio base station notification message including each radio base station of the selected destination candidate and information regarding the communication quality of these radio base stations. The mobile terminal apparatus determines the destination radio base station based on various information in the destination candidate radio base station notification message and the received channel quality from each radio base station.

JP 2004-128636 A JP 2003-348007 A

  However, in radio resource allocation in a mobile network, radio resources to be used change according to radio channel quality. For this reason, there has been a problem that the conventional techniques described in Patent Documents 1 and 2 that select or select a destination base station by reporting or notifying radio resources cannot be applied to a mobile network.

  Also, depending on the moving speed of the mobile device, a cell selection method that allocates a larger cell as the moving speed is faster and a route on the wired side of the base station are considered (for example, a cell whose route on the wired side becomes complicated). When using the cell selection method, the destination base station (movement destination cell) is selected according to the radio channel quality and radio resource usage using the conventional techniques described in Patent Documents 1 and 2 above. As a result, there is a problem that the criteria for selecting cells that are selection candidates are limited.

  Furthermore, in a mobile network having a plurality of radio frequencies and radio access methods, there is a limit to the measurement capability of the radio quality line of the peripheral cell in the mobile station, and handover is performed in a handover where the radio frequency or radio access method is changed. As a result, communication quality deteriorates. For this reason, in a mobile network having a plurality of radio frequencies and radio access methods, there is a problem that the peripheral cell in which the mobile device measures the radio channel quality must also be selected in consideration of the measurement capability of the mobile device. there were.

  The present invention has been made in view of the above, and determines a handover destination cell according to the degree of radio channel quality measured by a mobile device when radio resources to be used change according to radio channel quality. Thus, a first object is to obtain a wireless communication system that performs handover.

  The second object is to provide a radio communication system capable of reducing the addition of measurement of radio channel quality measured for determining a handover destination of a mobile device.

  In order to solve the above-described problems and achieve the object, the present invention includes a plurality of base stations that control at least one cell and are connected to a mobile device via a radio channel, and at least one of the plurality of base stations. In the wireless communication system, comprising: a plurality of edge routers to be accommodated; and a plurality of routers that accommodate at least one of these edge routers and are connected to the handover control server and the second network via the first network. The station includes a use resource measurement unit that measures a use resource for each cell controlled by the own station, and notifies the measured use resource to the handover control server, and the handover control server corresponds to the plurality of base stations. In addition, a radio access method including the frequency used by the base station, cell information controlled by the base station, and accommodating the base station An edge router, a network configuration storage unit that stores network configuration information related to a router that accommodates the edge router, a cell configuration storage unit that stores cell configuration information related to a cell configuration controlled by the plurality of base stations, and the base A use resource storage unit that stores use resource information associated with a base station used resource notified from a station, a radio access capability notified from the mobile device, and network configuration information stored in the network configuration storage unit Based on the cell configuration information stored in the cell configuration storage unit and the use resource information stored in the use resource storage unit, a weight function for each neighboring cell of the cell to which the mobile station is currently connected is obtained. A set of the calculated weighting function and the weighting function identifier for identifying the weighting function. A weight function calculation unit for notifying the mobile device of weight function information, weight function information generated by the weight function calculation unit, network configuration information stored in the network configuration storage unit, and cell configuration storage unit Based on the stored cell configuration information, the weight function identifier of the neighboring cell in association with the neighboring cell, the base station that controls the neighboring cell, the radio access scheme of the base station, and the edge that accommodates the base station A cell list generating unit that generates a cell list in which information related to a router and a router for identifying the edge router is registered, and notifies the generated cell list to the mobile device, the mobile device including the handover control Neighboring cell list storage unit for storing the cell list notified from the server, and notified from the handover control server Radio channel quality for measuring radio channel quality between a weight function storage unit for storing weight function information and each peripheral cell registered in the cell list stored in the peripheral cell list storage unit and a currently connected cell A measurement unit; a radio channel quality measured by the radio channel quality measurement unit; a cell list stored in a peripheral cell list storage unit; weight function information stored in a weight function storage unit; Based on the capability, a predetermined parameter is input to the weight function in the weight function information to calculate a neighboring cell selection parameter of each cell, and a handover destination candidate cell is selected based on the calculated neighboring cell selection parameter A neighboring cell selection parameter calculation / comparison unit, and a handover destination candidate selected by the neighboring cell selection parameter calculation / comparison unit Among the cells having the neighbor cell selection parameter with the better communication quality than the currently connected cell, the cell having the neighbor cell selection parameter with the best communication quality is determined as the handover destination cell. And a neighboring cell selection determining unit that performs a handover process on the cell.

  In the radio communication system according to the present invention, the handover control server is based on the network configuration information and cell configuration information of the radio communication system, the radio access capability of the mobile device, and the resource used for each cell measured by each base station. The mobile device calculates a weight function for each neighboring cell of the cell in communication, and notifies the mobile device of weight function information including a set of the calculated weight function and a weight function identifier for identifying the weight function. , Based on the weight function information, network configuration information, and cell configuration information, the weight function identifier of the neighboring cell in association with the neighboring cell, the base station that controls the neighboring cell, the radio access scheme of the base station, the base Generate a cell list that contains information about the edge router that houses the station and the router that identifies the edge router. The list is notified to the mobile station, and the mobile station measures the radio channel quality of the neighboring cells registered in the cell list notified from the handover control server and the currently connected cell, and the measured radio channel quality and handover Since the neighbor cell selection parameter is calculated using the weight function information and the cell list notified from the control server and the handover destination cell is determined, depending on the radio channel quality measured by the mobile station There is an effect that it is possible to obtain a radio communication system that performs handover by determining a handover destination cell.

FIG. 1 is a schematic diagram showing a configuration of a wireless communication system according to the present invention. FIG. 2 is a diagram illustrating an example of a cell configuration of the radio access network illustrated in FIG. FIG. 3 is a block diagram showing a functional configuration related to the handover process of the base station shown in FIG. FIG. 4 is a block diagram showing a functional configuration related to the handover process of the handover control server shown in FIG. FIG. 5 is a diagram illustrating an example of the configuration of network configuration information stored in the network configuration storage unit illustrated in FIG. FIG. 6 is a diagram illustrating an example of the configuration of the cell configuration information stored in the cell configuration storage unit illustrated in FIG. FIG. 7 is a diagram illustrating an example of a cell list generated by the cell list generation unit illustrated in FIG. FIG. 8 is a block diagram showing a functional configuration related to the handover process of the mobile device shown in FIG. FIG. 9 is a flowchart for explaining the operation of the handover control server of the first embodiment. FIG. 10 is a flowchart for explaining the operation of the mobile device of the first embodiment. FIG. 11 is a sequence diagram for explaining the operation of the wireless communication system according to the first embodiment. FIG. 12 is a block diagram showing a functional configuration related to the handover process of the mobile device of the second embodiment. FIG. 13 is a block diagram showing a functional configuration related to the handover process of the handover control server of the second embodiment. FIG. 14 is a sequence diagram for explaining the operation of the radio communication system according to the second embodiment.

  Hereinafter, embodiments of a radio communication system, a base station, a mobile device, and a handover control server according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram showing a configuration of a wireless communication system according to the present invention. In FIG. 1, a wireless communication system includes a mobile network 9, an Internet 10 connected to the mobile network 9, and another mobile device or a fixed terminal connected to the wireless access network 6 through a wireless line via the Internet 10. And a mobile device (MS) 1 that communicates with the above.

  The mobile network 9 is composed of a radio access network 6 and a core network 7. The radio access network 6 controls a plurality of (seven in this case) base stations (BS) 2 (shown as 2-1 to 2-7) connected to the mobile device 1 through a wireless line and handover of the mobile device 1. A handover control server (HOS) 3 is provided.

  The core network 7 routes a plurality of edge routers (Edge Routers) 4 (indicated by 4-1 to 4-3) that accommodate the base station 2 to the edge router 4 and the edge router 4. A plurality of (in this case, two) routers (Routers) 5 (shown as 5-1 and 5-2) accommodating the router 4, and an IP network (route) 5, the handover control server 3, and the Internet 10 connected ( IP-Network) 8.

  In FIG. 1, the edge router 4-1 accommodates the base station 2-7 via a wired line, the edge router 4-2 accommodates the base stations 2-1 and 2-5 via a wired line, and the edge router 4-3. Accommodates 2-2, 2-3 and 2-6 by wire, and the base station 2-4 is accommodated in the edge router 4-3 via the base station 2-3 by a wireless line.

  FIG. 2 is a diagram showing an example of a cell configuration of the radio access network 6 shown in FIG. In FIG. 2, cells 11-1-1 to 11-1-6 are controlled by a base station 2-1, cells 11-2-1 to 11-2-5 are controlled by a base station 2-2, and a cell 11 -3-1 to 11-3-5 are controlled by the base station 2-3, the cells 11-4-1 to 11-4-5 are controlled by the base station 2-4, and the cells 11-5-1 to 11-11 are controlled. -5-6 is controlled by the base station 2-5, the cells 11-6-1 to 11-6-6 are controlled by the base station 2-6, and the cells 11-7-1 to 11-7-4 Controlled by stations 2-7. The number of cells controlled by the base station 2 may be any number as long as it is 1 or more.

  The wireless communication system according to the present invention is configured as shown in FIG. 1, and the base station 2 and the handover control server 3 communicate with each other via the edge router 4, the router 5, and the IP network 8. In addition, the mobile device 1 and the handover control server 3 communicate with each other via the base station 2, the edge router 4, the router 5, and the IP network 8.

  Next, with reference to FIG. 3 to FIG. 7, a functional configuration related to the handover process of the base station 2, the mobile device 1, and the handover control server 3 illustrated in FIG. 1 will be described.

  First, a functional configuration related to the handover process of the base station 2 will be described. Base stations 2-1, 2-5 to 2-7 are base stations connected to the mobile device 1 by the same radio access method and use frequency, and base stations 2-2 to 2-4 are base stations 2-2. Although the base station 2 is connected to the mobile device 1 by a radio access method different from 1, 2-5 to 2-7, or by use frequency, the functional configuration related to the handover processing does not depend on the radio access method and use frequency. Are the same.

  The base station 2 is a cell in which its own station controls resources used by itself, such as radio resources, wired resources, and device resources (such as buffering sources and CPU usage rates) in accordance with instructions from the handover control server 3. Measurement is performed every time, and the measured use resource is notified to the handover control server 3.

  FIG. 3 is a block diagram showing a functional configuration related to the handover process of the base station 2 shown in FIG. In FIG. 3, the base station 2 has an interface function for a wired line connected to the edge router 4 and has a wired line termination unit 21 for terminating the wired line, and an interface function for a wireless line connected to the mobile device 1. A wireless channel transmission / reception unit 23 that transmits and receives signals according to the above, and a usage resource measurement unit 22 that measures the usage resource for each cell controlled by the local station and notifies the handover control server 3 according to an instruction from the handover control server 3. Yes.

  Next, a functional configuration related to the handover process of the handover control server 3 will be described. The handover control server 3 uses the resources notified from the base station 2, the network configuration information of the mobile network 9 managed by the own device, and the cells 11 (11-1-1-1 to 11-1-6 controlled by the base station 2. 11-2-1-11-2-5, 11-3-1 to 11-3-5, 11-4-1 to 11-4-5, 11-5-1 to 11-5-6, 11 -6-1 to 11-6-6, 11-7-1 to 11-7-4). A cell list is generated based on the cell configuration information indicating the configuration of To the mobile device 1.

  FIG. 4 is a block diagram showing a functional configuration related to the handover process of the handover control server 3 shown in FIG. In FIG. 4, the handover control server 3 includes a wired line termination unit 31, a network configuration storage unit 36, a cell configuration storage unit 37, a base station communication control unit 32, a used resource storage unit 38, a cell list generation unit 34, and a weight function calculation. And a mobile unit communication control unit 33.

  The wired line termination unit 31 has an interface function for a wired line connected to the IP network 8 and terminates the wired line. The network configuration storage unit 36 stores network configuration information indicating the network configuration of the mobile network 9. In the network configuration information, information related to the network configuration is registered among information necessary for the cell list generation unit 34 to create a cell list.

  FIG. 5 is a diagram illustrating an example of the configuration of network configuration information stored in the network configuration storage unit 36 illustrated in FIG. In FIG. 5, in the network configuration information, a base station identifier for identifying the base station 2 is registered in the base station 100, and the wireless access of the base station 2 registered in the base station 100 is registered in the wireless access method 101. The system (including the used frequency) is registered, and in the cell information 102, a cell identifier for identifying the cell 11 controlled by the base station 2 registered in the base station 100 is registered. An edge router identifier for identifying the edge router 4 accommodating the base station 2 registered in the base station 100 is registered, and the accommodating router 104 accommodates the router 5 accommodating the edge router 4 registered in the accommodating edge router 103. A router identifier for identifying is registered.

  In FIG. 5, the radio access scheme “A” is registered in the radio access scheme 101 in association with the base station identifier “BS # 1” of the base station 2-1 registered in the base station 100, and the cell information 102 contains the cell The cell identifiers “Cell # 1-1 to Cell # 1-6” of 11-1-1 to 11-1-6 are registered, and the edge router identifier “ER # 2” of the edge router 4-2 is registered in the accommodating edge router 103. Is registered, and the router identifier “R # 1” of the router 5-1 is registered in the accommodating router 104. Further, in association with the base station identifier “BS # 2” of the base station 2-2 registered in the base station 100, the wireless access method “B” is registered in the wireless access method 101, and the cell 11− The cell identifiers “Cell # 2-1 to Cell # 2-5” of 2-1 to 11-2-5 are registered, and the edge router identifier “ER # 3” of the edge router 4-3 is registered to the accommodating edge router 103. The router identifier “R # 2” of the router 5-2 is registered in the accommodating router 104. In FIG. 5, only the base stations 2-1 and 2-2 are illustrated, but actually, each piece of information associated with the base station 2 managed by the handover control server 3 is registered.

  The cell configuration storage unit 37 stores cell configuration information of the radio access network 6. The cell configuration information includes information related to the configuration of the cell 11 among information necessary for the weight function calculation unit 35 to generate a weight function and information necessary for the cell list generation unit 34 to create a cell list. Is registered.

  FIG. 6 is a diagram illustrating an example of the configuration of the cell configuration information stored in the cell configuration storage unit 37 illustrated in FIG. In FIG. 6, the cell configuration information includes a reference cell 200, a base station 201, and an adjacent cell 202. The cell identifier of the cell 11 is registered in the reference cell 200, the base station identifier of the base station 2 that controls the cell 11 registered in the reference cell 200 is registered in the base station 201, and the reference cell 202 is registered in the reference cell 202. The cell identifier of the cell 11 adjacent to the cell 11 registered in the cell 200 is registered.

  In FIG. 6, the base station 201 associates the base station identifier “BS # 1” of the base station 2-1 with the cell identifier “Cell # 1-1” of the cell 11-1-1 registered in the reference cell 200. And “BS # 5” are registered, and the cell identifier “Cell # 1-2” of the cells 11-1-2 to 11-1-6 is associated with the base station identifier “BS # 1” in the adjacent cell 202. Cell # 1-6 ”and the cell identifier“ Cell # 5-3 ”of the cell 11-5-3 are registered in association with the base station identifier“ BS # 5 ”.

  Further, in association with the cell identifier “Cell # 1-2” of the cell 11-1-2 registered in the reference cell 200, the base station 201 has base stations 2-1, 2-2, and 2-6 base stations. Identifiers “BS # 1”, “BS # 2”, and “BS # 6” are registered, and adjacent cells 202 are associated with the base station identifier “BS # 1” in cells 11-1-1 and 11-1- 3, 11-1-6 cell identifiers “Cell # 1-1”, “Cell # 1-3”, “Cell1-6” are registered, and the cell 11− is associated with the base station identifier “BS # 2”. 2-1 and 11-2-2 cell identifiers “Cell # 2-1” and “Cell # 2-2” are registered, and the cell 11-6-3 is associated with the base station identifier “BS # 6”. The cell identifier “Cell # 6-3” is registered.

  In FIG. 6, only the cells 11-1-1 and 11-1-2 are shown, but actually, the base station managed by the handover control server 3 in the mobile network 9 shown in FIG. Information using the cell 11 controlled by 2 as a reference cell is registered.

  The base station communication control unit 32 controls the communication with the base station 2 and is based on the network configuration information stored in the network configuration storage unit 36 and the cell configuration information stored in the cell configuration storage unit 37. Thus, the base station 2 that controls the cell to be controlled by itself is requested to use resources.

  The use resource storage unit 38 stores use resource information for registering the use resource notified from the base station 2 in association with the base station 2 in response to a request from the base station communication control unit 32. As described above, the used resource is measured for each cell controlled by the base station 2. That is, the use resource is notified from the base station 2 in association with the measured cell identifier, such as a radio resource, a wired resource, and a device resource (such as an internal buffering source and a CPU usage rate). The The used resource storage unit 38 stores the used resource information in which the base station identifier of the base station 2 (the base station 2 that transmitted the used resource) that controls the cell 11 indicated by the measured cell identifier is associated with the measured cell identifier. Remember.

  The weighting function calculating unit 35 is a wireless access capability notified from the mobile device 1, used resource information stored in the used resource storage unit 38, network configuration information stored in the network configuration storage unit 36, and cell configuration storage. Based on the cell configuration information stored in the unit 37, a weight function for each cell is generated. The weighting function is a function that outputs a neighboring cell selection parameter for selecting whether or not the mobile station 1 performs a handover with the radio channel quality as an input. The weight function calculation unit 35 manages the weight function identifier for identifying the calculated weight function, the weight function, and the cell identifier from which the weight function is calculated in association with each other.

  The cell list generation unit 34 is based on the weight function for each cell generated by the weight function calculation unit 35, the network configuration stored in the network configuration storage unit 36, and the cell configuration stored in the cell configuration storage unit 37. A cell list for the mobile device 1 is generated.

  FIG. 7 is a diagram illustrating an example of a cell list generated by the cell list generation unit 34 illustrated in FIG. In the cell list, the neighboring cell 300, the weight function 301, the base station 302, the radio access scheme 303, the accommodating edge router 304, and the accommodating router 305 are registered.

  In the peripheral cell 300, the cell identifier of the cell 11 selected as the peripheral cell is registered. In the weight function 301, the weight function identifier of the weight function for the cell 11 registered in the neighboring cell 300 is registered. In the base station 302, the base station identifier of the base station 2 that controls the cell 11 registered in the neighboring cell 300 is registered. In the wireless access method 303, the wireless access method of the base station 2 registered in the base station 302 is registered. In the accommodating edge router 304, the edge router identifier of the edge router 4 accommodating the base station 2 registered in the base station 302 is registered. In the accommodating router 305, the router identifier of the router 5 that accommodates the edge router 4 registered in the accommodating edge router 304 is registered.

  The mobile communication control unit 33 sets the weight function information obtained by combining the weight function calculated by the cell list generated by the cell list generating unit 34 and the weight function calculated by the weight function calculating unit 35 and the weight function identifier to the wired line terminating unit 31. And transmitted to the mobile device 1 via the base station 2.

  Next, a functional configuration related to the handover process of the mobile device 1 will be described. The mobile device 1 performs a handover based on information registered in the cell list notified from the handover control server 3 via the base station 2 and the radio channel quality.

  FIG. 8 is a block diagram showing a functional configuration related to the handover process of the mobile device 1 shown in FIG. In FIG. 8, the mobile device 1 includes a radio channel transceiver unit 17, a neighboring cell list storage unit 13, a weight function storage unit 12, a radio channel quality measurement unit 14, a neighboring cell selection parameter calculation / comparison unit 15, and a neighboring cell selection decision. A portion 16 is provided.

  The wireless line transmitting / receiving unit 17 has an interface function of a wireless line connected to the base station 2 and transmits and receives wireless signals. The neighboring cell list storage unit 13 stores a cell list notified from the handover control server 3 via the base station 2. The weight function storage unit 12 stores weight function information notified from the handover control server 3.

  The radio channel quality measurement unit 14 measures the radio channel quality for each cell indicated by the cell identifier in the cell list stored in the neighboring cell list storage unit 13 for each predetermined period. The radio channel quality measurement unit 14 measures the radio channel quality with the base station 2 in communication.

  The neighboring cell selection parameter calculation / comparison unit 15 determines each cell based on the radio channel quality of each cell measured by the radio channel quality measurement unit 14 and the weight function information of each cell stored in the weight function storage unit 12. The neighboring cell selection parameter is calculated, and based on the calculated neighboring cell selection parameter, a handover destination candidate cell is selected.

  The neighboring cell selection determination unit 16 determines a handover destination cell from the handover destination candidates selected by the neighboring cell selection parameter calculation / comparison unit 15 and executes a handover process.

  Next, the operation of the wireless communication system according to the present invention will be described with reference to FIGS. First, the operation of the base station 2 will be described. Upon receiving the use resource transmission request from the handover control server 3 via the wired line termination unit 21, the use resource measurement unit 22 measures the use resource of the cell 11 controlled by the own station based on the use resource transmission request, The measured use resource is transmitted to the handover control server 3 via the wired line termination unit 21.

  The use resource transmission request received from the handover control server 3 is, for example, a periodic report request that the base station 2 periodically measures and reports the use resource, or a use that the base station 2 measures and reports the use resource at the time of the request. A resource request, a report request for measuring and reporting a resource used when the base station 2 newly assigns a radio resource, a wired resource, and a device resource to the mobile device 1; the base station 2 periodically measures the resource used; There is an excess report request for reporting the measured used resource only when the measured used resource exceeds a predetermined threshold.

  When the periodic report request is received, the used resource measurement unit 22 measures the used resource of the cell 11 controlled by the own station at every predetermined measurement cycle or every measurement cycle included in the periodic report request, and performs handover control. Send to server 3. When receiving the use resource request, the use resource measuring unit 22 measures the use resource of the cell 11 controlled by the own station, and transmits the measured use resource to the handover control server 3.

  When receiving a report request, the used resource measuring unit 22 measures the used resource when the base station 2 newly assigns a radio resource, a wired resource, and a device resource to the mobile device 1 and performs handover control on the measured used resource. Send to server 3.

  When the excess report request is received, the use resource measurement unit 22 measures the use resource of the cell 11 controlled by the own station every predetermined measurement cycle or every measurement cycle included in the excess report request. The used resource measurement unit 22 determines that the measured used resource, that is, the wireless resource or the wired resource, the buffering source inside the own station, and the CPU usage rate exceed a predetermined threshold value or a threshold value included in the excess report request, respectively. It is determined whether or not. When at least one value exceeds the threshold value, the used resource measuring unit 22 transmits the measured used resource to the handover control server 3.

  Next, the operation of the handover control server 3 according to the first embodiment will be described. FIG. 9 is a flowchart for explaining the operation of the handover control server 3 of the first embodiment. Based on the cell configuration information stored in the cell configuration storage unit 37, the base station communication control unit 32 selects the base station 2 that controls the cell to be controlled by itself (step S100).

  Specifically, the position of the mobile device 1 is registered in advance in the handover control server 3 via the base station 2. The base station communication control unit 32 recognizes the cell 11 in which the mobile device 1 is located from this location registration. Here, it is assumed that the mobile device 1 is located in the cell 11-1-1. The base station communication control unit 32 uses the cell identifier “Cell # 1-1” indicating the cell 11-1-1 where the mobile device 1 is located as a search key, and the reference cell 200 of the cell configuration information shown in FIG. The base station identifier registered in association with the search key and the cell identifier of the neighboring cell are acquired. Here, base station identifiers “BS # 1” and “BS # 5” and “Cell # 1-2 to Cell # 1-6” and “Cell # 5-3” are acquired as cell identifiers of neighboring cells.

  In the base station communication control unit 32, information related to neighboring cells to be selected as neighboring cells is set in advance. The information related to the peripheral cell is information indicating how many neighbors are selected as the peripheral cell from the cell where the mobile device 1 is located. If the information about the neighboring cell is adjacent to one another, the base station communication control unit 32 determines that the cells 11-1-2 to 11-1-6 and 11-5 adjacent to the cell 11-1-1 where the mobile device 1 is located. -3 (see FIG. 2) is selected as a peripheral cell. That is, the neighboring cell 101 registered in association with the reference cell 200 of the cell configuration information shown in FIG. 6 is a neighboring cell.

  Moreover, if the information regarding a neighboring cell is 2 adjacent, the base station communication control part 32 will be the cells 11-1-2 to 11-1-6, 11 adjacent to the cell 11-1-1 in which the mobile device 1 is located. -5-3, and cells 11-2-1, 11-2-2, 11-3-3, 11- adjacent to these cells 11-1-2 to 11-1-6, 11-5-3 3-4, 11-4-2, 11-4-3, 11-5-1, 11-5-2, 11-5-4, 11-6-3, 11-6-4, 11-7- 2 (see FIG. 2) is selected as a peripheral cell. That is, the reference cell 200 is searched using each cell identifier registered in the adjacent cell 202 acquired using the cell 11 in which the mobile device 1 is located as a search key, and is associated with the reference cell 200 that matches the search key. Then, the base station identifier and the cell identifier registered in the base station 201 and the neighboring cell 202 are acquired, and all the acquired cell identifiers (one overlapping cell identifier is selected) are selected as neighboring cells.

  The base station communication control unit 32 transmits a use resource transmission request to the base station 2 that controls the peripheral cell selected via the wired line termination unit 31, that is, the base station 2 indicated by the base station identifier acquired from the cell configuration information. (Step S101).

  When the use resource from the base station 2 is received via the wired line termination unit 31, the base station communication control unit 32 stores the use resource information obtained by adding the information of the base station 2 to the received use resource in the use resource storage unit 38. Store (steps S102, S103).

  The mobile device communication control unit 33 detects that the mobile device 1 has started communication and has established a radio line in a specific cell or moved (handed over) to a different cell by the location registration of the mobile device 1. After detecting that the neighboring cell has been changed and collecting used resource information from the base station 2 that controls the neighboring cells of the mobile device 1 by the operations of the above-described steps S100 to S103, the weight function for the mobile device 1 is collected. The derivation instruction is output to the weight function calculation unit 35.

  Upon receiving the weight function derivation instruction, the weight function calculation unit 35 receives the wireless access capability notified from the mobile device 1, the use resource information stored in the use resource storage unit 38, and the network stored in the network configuration storage unit 36. A weight function for each cell is generated based on the configuration information and the cell configuration information stored in the cell configuration storage unit 37 (steps S104 and S105).

  Specifically, the weight function calculation unit 35 uses the resource used for each cell of the resource used information, the radio access method and the accommodation edge router registered in the network configuration information in association with the base station 2 that controls the cell, Information on the positional relationship between the cell 11 in which the mobile device 1 is located and the target cell for calculating the weighting function (whether it is 1 neighbor or 2 neighbors) from the performance and usage status of the accommodating router and the cell configuration information Based on the above, a weighting function for weighting the radio channel quality when selecting the cell to be handed over is calculated.

  The weight function calculation unit 35 associates the calculated weight function with the weight function information that sets the weight function for identifying the weight function and the cell identifier of the cell for which the weight function is calculated, and notifies the cell list generation unit 34 of the association. . When the weight function calculation unit 35 notifies the cell list generation unit 34 of the weight function information, the weight function calculation unit 35 determines whether or not the cell is suitable as a neighboring cell. The code is different from the weight function such as “Null”.

  The neighboring cell inappropriate as the neighboring cell is, for example, the same radio access scheme of the base station 2 that controls the cell where the mobile device 1 is located and the cell adjacent to the cell selected as the neighboring cell, In addition, when there is a cell whose free capacity (used resource) is larger than a predetermined threshold, a cell with a radio access scheme different from the cell in which the mobile device 1 is located among the cells selected as neighboring cells. is there.

  Further, when establishing communication, the handover control server 3 is notified of the radio access capability of the mobile device 1, the amount of resources required for communication, and the communication quality, and these pieces of information are registered. The weight function calculation unit 35 determines whether or not it is appropriate as a peripheral cell based on these pieces of information. Here, the wireless access capability is a wireless access method or frequency that can be used by the mobile device 1, and is the minimum required wireless band and wired band as the amount of resources required for communication. Communication quality is bit error. Such as rate and delay quality.

  The determination as to whether or not the cell is appropriate as a neighboring cell may be made based on the radio access capability of the mobile device 1, the amount of resources required for communication, communication quality, used resource information, cell configuration information, and network configuration information. In addition, after determining whether it is appropriate as a peripheral cell, the weight function may be generated only for the peripheral cell determined to be appropriate.

  The cell list generation unit 34 includes the weight function information and cell identifier notified from the weight function calculation unit 35, the network configuration information stored in the network configuration storage unit 36, and the cell configuration stored in the cell configuration storage unit 37. A cell list (see FIG. 7) is generated based on the information (step S106).

  Specifically, the cell list generation unit 34 registers the cell identifier associated with the weight function information notified from the weight function calculation unit 35 in the neighboring cell 300, and the weight function in the weight function information is registered in the weight function 301. Register an identifier. The cell list generation unit 34 searches for the neighboring cell 202 in the cell configuration information using the cell identifier registered in the neighboring cell 300 as a search key, and is registered in the base station 201 in association with the neighboring cell 202 that matches the search key. Get a base station identifier. The cell list generation unit 34 registers the acquired base station identifier in the base station 302.

  In addition, the cell list generation unit 34 searches the base station 100 in the network configuration information using the acquired base station identifier as a search key, and registers the radio access scheme registered in association with the base station 100 that matches the search key. , The accommodated edge router identifier and the accommodated router identifier are obtained. The cell list generation unit 34 registers the acquired wireless access method in the wireless access method 303, registers the acquired accommodated edge router identifier in the accommodated edge router 304, and registers the acquired accommodated router identifier in the accommodated router 305.

  For each weight function information and cell identifier notified from the weight function calculation unit 35, the cell list generation unit 34 stores the weight function information and cell identifier notified from the weight function calculation unit 35 in the network configuration storage unit 36. A cell list is generated based on the network configuration information being stored and the cell configuration information stored in the cell configuration storage unit 37. The cell list generation unit 34 does not register the weight function information whose weight function is “Null” in the cell list.

  The cell list generation unit 34 transmits the weight function information notified from the weight function calculation unit 35 and the generated cell list to the mobile device 1 via the wired line termination unit 31 and the base station 2 (step S107).

  Next, the operation of the mobile device 1 according to the first embodiment will be described. FIG. 10 is a flowchart for explaining the operation of the mobile device 1 according to the first embodiment. When the mobile device 1 receives the weighting function information and the cell list from the handover control server 3 via the wireless channel transmission / reception unit 17 (step S200), the mobile device 1 stores the received weighting function information in the weighting function storage unit 12 (step S201). The received cell list is stored in the neighboring cell list storage unit 13 (step S202).

  When the predetermined measurement time is reached, the radio channel quality measurement unit 14 performs radio channel communication with each cell indicated by the cell identifier registered in the neighboring cell 300 of the cell list stored in the neighboring cell list storage unit 13. Quality is measured (steps S203 and S204). The radio channel quality measurement unit 14 notifies the neighboring cell selection parameter calculation / comparison unit 15 of the measured radio channel quality of each cell in association with the cell identifier.

  The neighboring cell selection parameter calculation / comparison unit 15 stores the radio channel quality measured by the radio channel quality measurement unit 14, the cell list stored in the neighboring cell list storage unit 13, and the weight function storage unit 12. A neighboring cell selection parameter is calculated using the weight function information (step S205).

  Specifically, the neighboring cell selection parameter calculation / comparison unit 15 searches the neighboring cell 300 in the cell list using the cell identifier associated with the radio channel quality notified from the radio channel quality measurement unit 14 as a search key. Thus, the weight function identifier registered in the weight function 301 in association with the neighboring cell 300 that matches the search key is acquired.

  The neighboring cell selection parameter calculation / comparison unit 15 searches the weight function identifier of the weight function information stored in the weight function storage unit 12 using the acquired weight function identifier as a search key, and the weight function identifier that matches the search key The weight function registered in association with is acquired. The neighboring cell selection parameter calculation / comparison unit 15 substitutes the wireless channel quality notified from the wireless channel quality measurement unit 14 for the obtained weight function to calculate the neighboring cell selection parameter of the cell. The neighboring cell selection parameter calculation / comparison unit 15 stores the neighboring cell selection parameter calculated in association with the cell identifier of the neighboring cell (step S206).

  The neighboring cell selection parameter calculation / comparison unit 15 compares the wireless channel quality with the currently communicating cell 11 and a predetermined threshold value (step S207). When the wireless channel quality with the currently communicating cell 11 is smaller than a predetermined threshold value, that is, when the wireless channel quality with the currently communicating cell 11 cannot satisfy a predetermined value, the neighboring cell selection parameter calculation / comparison The unit 15 outputs a peripheral cell selection instruction to the peripheral cell selection determination unit 16.

  When receiving the peripheral cell selection instruction, the peripheral cell selection determination unit 16 performs communication more than the selection parameter of the cell 11 currently in communication among the peripheral cell selection parameters stored in the peripheral cell selection parameter calculation / comparison unit 15. It is determined whether there is a high-quality neighboring cell selection parameter (step S208). If it is determined that there is a neighboring cell selection parameter with better communication quality than the selection parameter of the cell 11 currently in communication, the neighboring cell selection determining unit 16 has a peripheral with better communication quality than the selection parameter of the currently communicating cell 11. Select cell selection parameters. When there are a plurality of neighboring cell selection parameters with better communication quality than the selection parameters of the cell 11 currently communicating, the neighboring cell selection determining unit 16 has the best neighboring cell selection parameter among the neighboring cell selection parameters. Select.

  The neighboring cell selection determining unit 16 determines the cell 11 having the selected neighboring cell selection parameter as a cell to be handed over. The neighboring cell selection determining unit 16 searches the neighboring cell 300 in the cell list stored in the neighboring cell list storage unit 13 using the cell identifier indicating the determined cell as a search key, and associates it with the cell identifier that matches the search key. The base station identifier, the radio access scheme, the accommodated edge router identifier, and the accommodated router identifier that are registered in this way are acquired and the handover process is executed (step S209).

  Next, the operation of the wireless communication system according to the first embodiment of the present invention will be described with reference to the sequence diagram of FIG. In FIG. 11, the number of base stations 2 is three (base stations 2-1 to 2-3), but the number of base stations 2 is not limited to this. The base stations 2-1 to 2-3 have received a periodic report request, and periodically use resources to report to the handover control server 3.

  When the mobile device 1 is not communicating, that is, when it is not connected to the base stations 2-1 to 2-3, the handover control server 3 receives information on neighboring cells (weight function information and cell list) for each cell unit. Is notified via the base stations 2-1 to 2-3. In this case, since the mobile device 1 is not communicating, the ability and communication quality of the mobile device 1 cannot be acquired. Therefore, the handover control server 3 calculates the weight function by calculating from the radio access method and frequency of the neighboring cells and the number of used resources of the base stations 2-1 to 2-3. In addition, when the mobile device 1 is not communicating, the weight function in the information on the neighboring cells to be notified may not be set.

  The base stations 2-1 to 2-3 have received a periodic report request from the handover control server 3, and periodically report use resources to the handover control server 3. When receiving the periodic report, the handover control server 3 updates the information for notification (information on neighboring cells) and notifies the information via the base stations 2-1 to 2-3.

  The mobile device 1 executes the procedure for shifting to the communication state. Here, the mobile device 1 establishes communication in the cell 11-1-1 controlled by the base station 2-1, and enters a communication state. The establishment of communication uses a communication establishment procedure in a general mobile network, but the mobile device 1 is required for the wireless access capability and communication of the mobile device 1 with respect to the handover control server 3 when establishing communication. Register resource amount and communication quality.

  The base stations 2-1 to 2-3 have received a periodic report request from the handover control server 3, and periodically report use resources to the handover control server 3. The handover control server 3 stores use resource information obtained by adding the base station identifiers of the base stations 2-1 to 2-3 to the use resources periodically reported from the base stations 2-1 to 2-3. The handover control server 3 generates a weight function for each cell based on the used resource information, the network configuration information, and the cell configuration information. The handover control server 3 generates weight function information in which the generated weight function is associated with the weight function identifier of the weight function.

  The handover control server 3 includes the wireless access capability received from the mobile device 1, the amount of resources required for communication and communication quality, the resources used reported from the base stations 2-1 to 2-3, and the surroundings obtained from the network configuration information. A neighboring cell is selected from the radio access capability (radio access method and frequency) of the cell.

  The handover control server 3 updates the cell list based on the selected neighboring cell, network configuration information, cell configuration information, and weight function information. The handover control server 3 notifies the mobile device 1 of the updated cell list and weight function information as information on neighboring cells.

  When the desired communication quality cannot be obtained in the wireless channel quality with the currently communicating cell 11-1-1, the mobile device 1 is based on the cell list in the information on neighboring cells notified from the handover control server 3. The wireless channel quality of the neighboring cell is measured, and the weighting function calculation for each cell is executed using the measured wireless channel quality and the wireless channel quality with the currently communicating cell 11-1-1 as input values, and the neighboring cell selection parameter Is calculated.

  When there is a neighboring cell selection parameter with higher quality than the neighboring cell selection parameter of the currently communicating cell 11-1-1, the mobile device 1 has a neighboring cell selection parameter of the currently communicating cell 11-1-1. A cell having a higher quality neighboring cell selection parameter is determined as a handover destination cell, and a predetermined handover procedure is executed. Here, it is assumed that the mobile device 1 is handed over from the base station 2-1 controlling the cell 11-1-1 to the cell controlled by the base station 2-2.

  When the handover procedure is executed, the number of radio resources used in the base station 2-2 that controls the handover destination cell changes. Therefore, the base station 2-2 reports to the handover control server 3 that the radio resource has been changed. The radio resource change report notifying that the radio resource has been changed is different from the periodic report, and is notified when the radio resource is changed.

  Upon receiving the radio resource change report, the handover control server 3 updates the use resource information, generates a weight function using the updated use resource information, and updates the weight function information and the cell list. The handover control server 3 notifies the mobile device 1 of the updated weight function information and information on neighboring cells including the cell list.

  As described above, in the first embodiment, the handover control server 3 uses the network configuration information and cell configuration information of the radio communication system, the radio access capability of the mobile station, and the resources used for each cell measured by each base station 2. Based on the above, the mobile device 1 calculates a weight function for each neighboring cell of the cell in communication, and moves the weight function information using the calculated weight function and a weight function identifier for identifying the weight function as a pair. In addition to the weight function information, the network configuration information, and the cell configuration information, the weight function identifier of the neighboring cell in association with the neighboring cell, the base station that controls the neighboring cell, the base station Generate a cell list that contains information on the wireless access method, the edge router that houses the base station, and the router that identifies the edge router. The generated cell list is notified to the mobile device 1, and the mobile device 1 measures and measures the radio channel quality of the neighboring cells registered in the cell list notified from the handover control server 3 and the currently connected cell. The neighbor cell selection parameter is calculated using the radio channel quality, the weight function information and the cell list notified from the handover control server 3, and the handover destination cell is determined.

  That is, the handover control server 3 notifies the mobile device 1 of a weighting function considering the wireless access capability of the mobile device, the resources used by the base station, and the wireless channel quality. Thereby, the handover destination cell can be determined flexibly according to the degree of the radio channel quality measured by the mobile device 1.

  In the first embodiment, the handover control server 3 receives a report of used resources from the base station 2, selects a neighboring cell, calculates a weight function for each neighboring cell, and notifies the mobile device 1 As an example, a plurality of base stations 2 are grouped and the functions of the handover control server 3 are distributedly mounted on the base stations 2 so that the same functions as those of the first embodiment can be realized. Good.

  Specifically, the base stations 2 in the wireless communication system are grouped in advance, and one of the base stations 2 in the group is added to the function of the base station 2 of the first embodiment, and the network of the handover control server 3 Assume that the base station 2 with a server function has the function of a handover control server further including a configuration storage unit 36, a cell configuration storage unit 37, a used resource storage unit 38, a weight function calculation unit 35, and a cell list generation unit 34.

  The base station 2 with the server function transmits a use resource transmission request to the base station 2 in the group where the own station exists, collects the use resource from the base station 2 in the group, and bases the collected use resource on the base Use resource information to which a station identifier is added is generated, neighboring cells are selected for cells controlled by the base station 2 in the group, and weight function information and a cell list are generated. The base station 2 with a server function notifies the mobile device 1 of the generated weight function information and cell list.

  In this way, the base function-equipped base station 2 selects the neighboring cells for the cells controlled by the base station 2 in the group in which the own station exists, and generates weight function information and a cell list. In addition, the processing load for generating the cell list can be distributed.

  In the first embodiment, the neighboring cell selection parameter calculation / comparison unit 15 of the mobile device 1 calculates the neighboring cell selection parameter when the radio channel quality with the currently communicating cell is lower than a predetermined threshold value. Then, the neighboring cell selection determination unit 16 determines the handover destination cell based on the neighboring cell selection parameter calculated by the neighboring cell selection parameter calculation / comparison unit 15. The calculation / comparison unit 15 calculates the neighboring cell selection parameter without comparing the radio channel quality with the currently communicating cell and a predetermined threshold, and the neighboring cell selection determining unit 16 A neighbor cell having a neighbor cell selection parameter with better communication quality than the neighbor cell selection parameter may be determined as a handover destination cell.

Embodiment 2. FIG.
A second embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the mobile device 1 determines the handover destination cell. However, in this second embodiment, the handover control server 3 determines the handover destination cell.

  The wireless communication system according to the second embodiment of the present invention includes a mobile device 1a and a handover control server 3a instead of the mobile device 1 and the handover control server 3 of the wireless communication system according to the first embodiment shown in FIG. I have.

  FIG. 12 is a block diagram showing a functional configuration related to the handover process of the mobile device 1a. The mobile device 1a shown in FIG. 12 includes the weight function storage unit 12, the peripheral cell selection parameter calculation / comparison unit 15, and the peripheral cell selection determination unit 16 of the mobile device 1 of the first embodiment shown in FIG. It has been deleted. Components having the same functions as those of the mobile device 1 according to the first embodiment shown in FIG.

  The radio channel quality measurement unit 14 measures the radio channel quality with the cell 11 indicated by the cell identifier registered in the neighboring cell 300 of the cell list stored in the neighboring cell list storage unit 13, and then the radio channel transmission / reception unit 17. Notify the handover control server 3a of the radio channel quality (including the radio channel quality with the cell in communication) measured through the base station 2.

  FIG. 13 is a block diagram showing a functional configuration related to the handover process of the handover control server 3a. In the handover control server 3a shown in FIG. 13, a weight function verification unit 39 is added to the handover control server 3 of the first embodiment shown in FIG. Components having the same functions as those of the handover control server 3 of the first embodiment shown in FIG. 4 are denoted by the same reference numerals, and redundant description is omitted.

  The weighting function verification unit 39 determines the neighboring cell selection parameters based on the radio channel quality notified from the mobile device 1a, the weighting function calculated by the weighting function calculation unit 35, and the cell list generated by the cell list generation unit 34. The handover destination cell is determined based on the calculated neighboring cell parameters. That is, it has the same functions as the neighboring cell selection parameter calculation / comparison unit 15 and the neighboring cell selection determination unit 16 of the mobile device 1 of the first embodiment shown in FIG.

  Next, the operation of the wireless communication system according to the second embodiment will be described with reference to the sequence diagram of FIG. The operation until the mobile device 1a enters the communication state is almost the same as the operation of the wireless communication system of the first embodiment described with reference to the sequence diagram of FIG. 11, and the difference is that In the wireless communication system according to the first embodiment, the handover control server 3 notifies the cell list and the weight function information as information on the neighboring cells, whereas in the wireless communication system according to the second embodiment, the handover control server 3a Since only the cell list is notified as cell information, the operation until the mobile device 1a enters the communication state is omitted.

  The base stations 2-1 to 2-3 receive a periodic report request from the handover control server 3a, and periodically report use resources to the handover control server 3. The handover control server 3a stores use resource information in which the base station identifiers of the base stations 2-1 to 2-3 are added to the use resources periodically reported from the base stations 2-1 to 2-3. The handover control server 3a generates a weight function for each cell based on the used resource information, the network configuration information, and the cell configuration information. The handover control server 3a stores the calculated weight function in association with the weight function identifier of the weight function as weight function information.

  The handover control server 3a includes the radio access capability received from the mobile device 1a when it enters the communication state, the resource amount and communication quality required for communication, the used resources reported from the base stations 2-1 to 2-3, the network A neighboring cell is selected from the wireless access capability (radio access method and frequency) of the neighboring cell obtained from the configuration information.

  The handover control server 3a updates the cell list based on the selected neighboring cell, network configuration information, cell configuration information, and weight function information. The handover control server 3a notifies the mobile device 1a of the updated cell list as neighboring cell information.

  The mobile device 1a measures the radio channel quality of the neighboring cell based on the cell list in the neighboring cell information notified from the handover control server 3a, and measures the measured radio channel quality and the currently communicating cell 11-1-1. Is associated with each cell identifier and notified to the handover control server 3a as a wireless quality measurement result notification.

  When the handover control server 3a receives the radio channel quality measurement result notification, the handover control server 3a determines a handover destination cell based on the radio channel quality measurement result notification, the weight function information, and the cell list.

  Specifically, when the radio channel quality of the cell 11-1-1 in communication with the mobile device 1a is smaller than a predetermined threshold value, that is, the radio channel quality with the cell 11 in communication can satisfy a predetermined value. When there is no more cell, the weight function verification unit 39 shown in FIG. 13 uses the cell identifier of the radio channel quality measurement result notification as a search key, and the neighboring cells of the cell list (see FIG. 7) generated by the cell list generation unit 34 300 is searched, and the weight function identifier registered in the weight function 301 in association with the neighboring cell 300 matching the search key is acquired.

  The weight function verification unit 39 searches for the weight identifier of the weight function information stored in the weight function calculation unit 35 using the acquired weight function identifier as a search key, and is registered in association with the weight identifier that matches the search key. Get weight function. The weight function verification unit 39 substitutes the radio channel quality of the radio channel quality measurement result notification associated with the cell identifier used as the search key for the acquired weight function, and calculates the neighboring cell selection parameter of the cell.

  The weight function verification unit 39 uses all cell identifiers in the radio channel quality measurement result notification as search keys, and selects the neighboring cell selection parameters for each cell and the neighboring cell of the cell 11-1-1 that the mobile device 1a is communicating with. After calculating the parameters, it is determined whether or not the calculated neighboring cell selection parameters include a neighboring cell selection parameter with better communication quality than the selected parameter of the currently communicating cell 11.

  When it is determined that there is a neighboring cell selection parameter with better communication quality than the selection parameter of the cell 11-1-1 in communication with the mobile device 1a, the weight function verification unit 39 determines the cell 11- in which the mobile device 1a is communicating. A neighboring cell selection parameter having better communication quality than the selection parameter 1-1 is selected, and a cell 11 having the selected neighboring cell selection parameter is determined as a handover destination cell.

  The handover control server 3a notifies the mobile device 1a of a handover destination cell notification including the cell identifier of the determined handover destination cell. Upon receiving the handover destination cell notification, the mobile device 1a executes the handover procedure with the cell indicated by the cell identifier in the handover destination cell notification as the handover destination cell. Here, it is assumed that the mobile device 1a is handed over from the base station 2-1 controlling the cell 11-1-1 to the cell controlled by the base station 2-2.

  When the handover procedure is executed, the base station 2-2 that controls the handover destination cell changes the number of radio resources used, and reports to the handover control server 3a that the radio resources have been changed.

  Upon receiving the radio resource change report, the handover control server 3a updates the use resource information, generates a weight function using the updated use resource information, and updates the weight function information and the cell list. The handover control server 3a notifies the mobile device 1a of information on neighboring cells including the updated cell list.

  As described above, in the second embodiment, the handover control server 3a uses the network configuration information and cell configuration information of the radio communication system, the radio access capability of the mobile device 1a, and the use for each cell measured by each base station 2. Based on the resource, the mobile device 1a calculates a weight function for each neighboring cell of the cell in communication, and weight function information that is a set of the calculated weight function and a weight function identifier for identifying the weight function. And generating a weight function identifier of the neighboring cell in association with the neighboring cell based on the weight function information, the network configuration information, and the cell configuration information, a base station that controls the neighboring cell, and a radio access scheme of the base station A cell list in which information about the edge router that accommodates the base station and the router that identifies the edge router is registered, The mobile device 1a notifies the mobile device of the formed cell list, and the mobile device 1a measures the radio channel quality of the peripheral cells registered in the cell list notified from the handover control server 3 and the currently connected cell, thereby measuring the handover control server. 3a, and the handover control server 3a determines the handover destination cell by calculating the neighboring cell selection parameters using the radio channel quality notified from the mobile station 1a, the weight function information and the cell list. Yes. As a result, the handover destination cell can be determined flexibly according to the degree of radio channel quality measured by the mobile device 1a.

  In the second embodiment, the weight function verification unit 39 of the handover control server 3a calculates the neighboring cell selection parameter when the radio channel quality with the currently communicating cell is lower than a predetermined threshold. The handover destination cell is determined based on the neighboring cell selection parameter, and the weight function verification unit 39 of the handover control server 3a determines the radio channel quality with the currently communicating cell and a predetermined threshold value. The neighboring cell selection parameter may be calculated without comparison, and a neighboring cell having a neighboring cell selection parameter with better communication quality than the neighboring cell selection parameter of the currently communicating cell may be determined as a handover destination cell.

  In the second embodiment, since the handover control server 3a calculates the neighboring cell selection parameter using the radio channel quality for each neighboring cell notified from the mobile device 1a, the cell list information notified to the mobile device 1a. As long as it includes information on neighboring cells whose radio channel quality is to be measured. Therefore, the cell list generation unit 34 of the handover control server 3a notifies the mobile device 1a only of the cell identifier of the neighboring cell and the base station identifier of the base station 2 that controls the neighboring cell in the generated cell list. It may be. Thereby, the amount of information that the handover control server 3a should notify to the mobile device 1a can be reduced.

  Further, the handover control server 3a according to the second embodiment receives a report of used resources from the base station 2, selects a neighboring cell, calculates a weight function for each neighboring cell, and notifies the mobile device 1a. Although described as an example, a plurality of base stations 2 may be grouped and the functions of the handover control server 3a may be distributedly mounted on the base stations 2 to realize the same functions as those of the second embodiment. .

  Specifically, the base stations 2 in the wireless communication system are grouped in advance, and one of the base stations 2 in the group is added to the function of the base station 2 of the second embodiment, and the network of the handover control server 3a Server function-equipped base having the function of a handover control server further comprising a configuration storage unit 36, a cell configuration storage unit 37, a used resource storage unit 38, a weight function calculation unit 35, a cell list generation unit 34, and a weight function verification unit 39 Station 2 is assumed.

  In this case, the base station with server function in which the neighboring cell selection parameter of the cell determined by the own station is exchanged between the base stations with server function 2 and the cell of the neighboring cell selection parameter having the best communication quality is determined as the handover destination cell. The station 2 may notify the mobile station 1a of the handover destination cell notification, or the master station of the base station 2 with a server function is designated in advance, and the base station 2 with a server function other than the master station Notify the station of the cell determined as the handover destination by the own station and the neighboring cell selection parameters of the cell, and the base station 2 with server function of the master station finally determines the handover destination cell and moves the handover destination cell notification You may make it notify to the apparatus 1a.

  In this way, the base station 2 with a server function selects a neighboring cell for a cell controlled by the base station 2 in a group in which the own station exists, generates weight function information and a cell list, and sets a neighboring cell selection parameter. By calculating, it is possible to distribute the processing load for generating the weight function information and the cell list and the processing load for calculating the neighboring cell selection parameters.

Embodiment 3 FIG.
In the first and second embodiments, the peripheral cells are selected only for the cell adjacent relationship. Therefore, in the cell configuration of FIG. 2, for example, when the mobile device 1 or the mobile device 1 a is located in the cell 11-1-1 and two adjacent cells are selected as neighboring cells, the cells 11-1-2 to 11-are selected. 1-6, 11-2-1, 11-2-2, 11-3-3, 11-3-4, 11-4-2, 11-4-3, 11-5-1 to 11-5 18 cells of 4,11-6-3, 11-6-4, and 11-7-2 are selected. In this case, cells having different radio access schemes and usable frequencies are also selected as neighboring cells, and the cell list shown in FIG. 7 is generated.

  A handover to a cell having a different frequency or radio access method used has a drawback such as an increase in the radio channel disconnection time required for the handover, and therefore there are cases where it is desired to exclude the handover from the handover destination cell. Conversely, the frequency utilization efficiency may deteriorate due to the concentration of traffic on a specific frequency or radio access scheme. In order to avoid such a situation, in the first and second embodiments, the weight function is changed according to the used frequency, the used radio access method, and the used resource of the cell.

  However, measuring the radio channel quality of different frequencies and different radio access methods also causes a problem that the processing load on the mobile device 1 or the mobile device 1a increases. For this reason, the mobile station 1 or the cell having a radio frequency with a different frequency or a different radio access method from a cell to be measured or a cell having a large use radio resource and less likely to be selected is excluded from the neighboring cells. It is desirable to notify the mobile device 1a.

  Therefore, in the third embodiment, the handover control server 3 or the handover control server 3a according to the first or second embodiment has a cell having a radio channel of a different frequency or a different radio access scheme from the cell to be measured. A function for generating a cell list by excluding cells that have a large use radio resource and are not likely to be selected from neighboring cells is provided.

  Specifically, for example, in the case of the handover control server 3a of the second embodiment, the expected radio channel quality of the radio channel measurement result in the mobile device 1 is further set in the weight function verification unit 39, and the input A function of notifying a cell identifier of a cell whose calculation result (neighbor cell selection parameter) obtained as a value is equal to or less than a predetermined neighbor cell selection threshold is added.

  In the case of the handover control server 3 according to the first embodiment, the weight function verification unit 39 having only the function of the weight function verification unit 39 according to the third embodiment may be provided.

  When the cell list is generated, the cell list generation unit 34 excludes the cell identifier notified from the weight function verification unit 39 and generates the cell list.

  Since the mobile device 1a measures the radio channel quality of the cell indicated by the cell identifier registered in the neighboring cell 300 of the cell list notified from the handover control server 3a, it has radio channels of different frequencies and different radio access methods. Measurement of the radio channel quality of a cell or a cell that has a large amount of radio resources to be used and is unlikely to be selected is eliminated, and the processing load for measuring the radio channel quality is reduced.

  As described above, in the third embodiment, the weight function verification unit 39 of the handover control server 3a uses the weight function calculated by the weight function calculation unit 35 using the preset expected radio channel quality. The selection parameter is calculated, and when the calculated value of the neighboring cell selection parameter is equal to or less than a predetermined neighboring cell selection threshold, the cell having the calculated neighboring cell selection parameter is excluded from the neighboring cells. Therefore, it is possible to reduce the number of cells in which the mobile device 1a measures the wireless channel, and it is possible to reduce the processing load by measuring the wireless channel quality of the mobile device 1a and to limit the cells that are candidates for the handover destination. be able to.

  A value obtained by degrading the neighboring cell selection threshold of the cell in the weight function verification unit 39 from the actual expected radio channel quality in the case where it is desired to suppress handover to a specific cell according to the management guidelines of the mobile network administrator. If it is set to (a value lower than the actual predicted radio channel quality), a specific cell can be prevented from being selected.

Embodiment 4 FIG.
In the wireless communication system of the first embodiment shown in FIG. 1, the cell in which the mobile device 1 is controlled by the base station 2-5, that is, the cells 11-5-1 to 11- having the cell configuration shown in FIG. It is assumed that communication is performed via the base station 2-5 located in any of 5-6. In this case, as described in the first embodiment, the handover control server 3 notifies the mobile device 1 of the cell list and the weight function information as information on neighboring cells.

  When the mobile device 1 is located in any of the cells 11-1-5-1 to 11-5-6, the cell 11-1- controlled by the base stations 2-1, 2-6, 2-7 as the peripheral cells 1-11-1-6, 11-6-1 to 11-6-6, and cells 11-7-1 to 11-7-4 may be included.

  The base station 2-5 and the base station 2-1 are accommodated in the same edge router 4-2, and the base stations 2-6 and 2-7 are edge routers 4- different from the base station 2-5. 3,4-1. The edge routers 4-1 and 4-2 are accommodated in the router 5-1 and connected to the IP network 8, and the edge router 4-3 is accommodated in the router 5-2 and connected to the IP network 8. Yes.

  The neighboring cell selection parameter calculation / comparison unit 15 and the neighboring cell selection determination unit 16 of the mobile device 1 measure the radio channel quality of the neighboring cells based on the cell list by the handover control server 3, and use the measured radio channel quality as input. A neighbor cell selection parameter is obtained by calculation of a weight function to determine a handover destination cell.

  Here, the neighboring cells 300 in the cell list include cells 11-6-1 to 11-6-6 and cells 11-7-1 to 11-7-4 controlled by the base stations 2-6 and 2-7. When any one of these cells 11-6-1 to 11-6-6, cells 11-7-1 to 11-7-4 has the best communication quality, Any one of the cells 11-6-1 to 11-6-6 and the cells 11-7-1 to 11-7-4 is determined as a handover destination cell, and the handover process is executed. As a result, when the handover process is executed for any of the cells 11-7-1 to 11-7-4 controlled by the base station 2-7, the routing of the core network 7 is the edge router 4-2. , The router 5-1 and the IP network 8 are changed to the edge router 4-1, the router 5-1, and the IP network 8, and the cells 11-6-1 to 11-6-6 controlled by the base station 2-6 When the handover process is executed for any one of the routing processes of the core network 7, the edge router 4-2, router 5-1, IP network 8, edge router 4-3, router 5-2, IP network It is changed to 8.

  Generally, as the number of routing change devices in the core network 7 increases, the processing delay in the core network 7 increases, and the radio channel switching quality at the time of handover of the mobile device 1 as the radio communication system deteriorates.

  Temporarily, the measurement results of the radio channel quality of the cells 11-7-1 to 11-7-4 controlled by the base station 2-7 measured by the radio channel quality measurement unit 14 of the mobile device 1, and the base station 2-6 There is a slight difference in radio channel quality from the cells 11-6-1 to 11-6-6 controlled by the cell 11-6-1, and 11-6-6 and 11-7-1 When the measurement result of 11-7-4 is also sufficient for the communication quality, the neighboring cell selection determining unit 16 of the mobile device 1 determines the cell having the best neighboring cell selection parameter as the handover destination cell. That is, there is a case where the cells 11-6-1 to 11-6-6 controlled by the base station 2-6 having a large number of routing changing devices are selected.

  In order to improve such a problem, the routing information in the core network 7 in which the base station 2 to which each cell is connected to the weight function for each cell notified by the handover control server 3 to the mobile device 1 is accommodated. This can be solved by using a function including a term that takes as input the number of devices that need to be switched. That is, the mobile device 1 may determine the handover destination cell in a form in which the routing information of the core network 7 is reflected from the result obtained when the mobile device 1 calculates the weight function.

  Specifically, when the weight function calculation unit 35 of the handover control server 3 calculates the weight function, the base station 100 of the network configuration information (see FIG. 5) stored in the network configuration storage unit 36, the accommodation edge The router 103 and the edge router 4 and router that accommodates the base station 2 that generates the routing information from the base station identifier, edge router identifier, and router identifier registered in the accommodating router 104 and controls the cell 11 that is currently communicating. 5 and a routing function between the edge router 4 and the router 5 that accommodates the base station 2 that controls the cell 11 that is a neighboring cell, and calculates a weighting function including a term with the number of devices that need to be switched as an input. To do. That is, the weight function calculation unit 35 of the handover control server 3 calculates a weight function taking routing into consideration.

  The neighboring cell selection parameter calculation / comparison unit 15 of the mobile device 1 includes a base station identifier, an edge router identifier registered in the base station 302, the accommodating edge router 304, and the accommodating router 305 in the cell list (see FIG. 7), and Routing information is generated from the router identifier, routing between the edge router 4 and the router 5 that accommodates the base station 2 that controls the cell 11 that is currently communicating, and the base station 2 that controls the cell 11 serving as a peripheral cell is accommodated. The routing between the edge router 4 and the router 5 determines the number of devices that need to be switched, and calculates a peripheral cell selection parameter from a weight function including a term with the determined number of devices as an input.

  As described above, in the fourth embodiment, the weight function calculation unit 35 of the handover control server 3 uses the network configuration information stored in the network configuration storage unit 36 to determine the base station 2, the edge router 4, and the router 5. Since the information about the routing path is extracted and a weight function including a term using the extracted information about the routing path as an input parameter is calculated, the cell whose routing path becomes complicated when determining the handover destination cell The selection probability can be suppressed.

Embodiment 5 FIG.
In the fourth embodiment, by calculating a weighting function taking routing into consideration, the processing delay due to the routing change is suppressed, and the radio channel switching quality at the time of handover of the mobile device 1 is improved. In the fifth embodiment, the condition different from the routing information is included in the term of the weight function to improve the radio channel switching quality at the time of handover of the mobile device 1.

  Conditions included in the term of the weight function include communication quality information, movement history, cell size (cell radius, base station maximum transmission power, etc.), used resources, and the like. First, a case where communication quality information is included as a term of a weight function will be described. Here, three parameters of a peak bit rate, an average bit rate, and a minimum bit rate are used as communication quality information of a call during communication of the mobile device 1. In this case, the weight function calculation unit 35 of the handover control server 3 includes a term having three parameters of the peak bit rate, the average bit rate, and the minimum bit rate as inputs in the weight function.

  The radio channel quality measurement unit 14 of the mobile device 1 measures the peak bit rate, the average bit rate, and the minimum bit rate during communication with the communication partner, and notifies the handover control server 3 of the measured bit rates.

  The neighboring cell selection parameter calculation / comparison unit 15 of the handover control server 3 calculates the neighboring cell selection parameter by substituting the peak bit rate, average bit rate, and minimum bit rate measured by the radio channel quality measurement unit 14 into the weight function. To do.

  Next, a case where the movement history is included as a term of the weight function will be described. The weight function calculation unit 35 of the handover control server 3 stores the movement history of the mobile device 1 in units of cells, and uses the stored movement history of the mobile device 1 as an input parameter when calculating the weight function. Calculate the weight function to include.

  The mobile device 1 stores the movement history moved by performing the handover process in units of cells, and the neighboring cell selection parameter calculation / comparison unit 15 substitutes the stored movement history into the weight function to select the neighboring cell. Calculate the parameters.

  Next, a case where the cell size is included as a term of the weight function will be described. First, a cell radius, a base station maximum transmission power, and the like are included in the cell configuration information stored in the cell configuration storage unit 37 as the cell size. Specifically, the cell radius is registered in association with the cell identifier registered in the reference cell 200 of the cell configuration information, and is associated with the base station identifier registered in the base station 201 in association with the cell identifier. To register the maximum transmission power of the base station.

  The weight function calculation unit 35 of the handover control server 3 calculates a weight function including a term having the cell radius and the base station maximum transmission power as input parameters. On the other hand, the cell list generation unit 34 generates a cell list including information on the cell radius of the cell 11 selected as the neighboring cell from the cell configuration information and the base station maximum transmission power of the base station 2 that controls the selected cell 11. To do.

  The neighboring cell selection parameter calculation / comparison unit 15 of the mobile device 1 obtains the cell radius of the neighboring cell and the base station 2 maximum transmission power of the base station 2 that controls the neighboring cell from the cell list, and obtains the obtained cell radius and base station. The neighboring cell selection parameter is calculated by substituting the maximum transmission power into the weight function.

  If the weight function calculation unit 35 of the handover control server 3 calculates a weight function including a term that combines the movement history and the cell size, the cell size of the mobile device 1 that is moving at high speed can be obtained. It is also possible to make it easy to determine a large cell as a handover destination cell.

  Next, a case where the used resource is included as a term of the weight function will be described. The weight function calculation unit 35 of the handover control server 3 uses the radio resource and wired resource of the base station 2 that controls the neighboring cells, the buffering source inside the base station 2 based on the use resource information stored in the use resource storage unit 38. And a weighting function including a term in consideration of resources used such as CPU usage rate. Since the used resource is measured for each cell, it is a value that can be calculated if the cell identifier registered in the neighboring cell 300 of the cell list is determined. Therefore, the term of the weight function related to the resource used may be a cell identifier input as an input parameter, or a value calculated in advance may be a coefficient or an addition number.

  Since the movement history and used resources are parameters that change with the passage of time, if a forgetting factor with the elapsed time as a parameter is incorporated in the mobile device 1 in advance, instantaneous traffic fluctuations and movement speeds It is also possible to absorb instantaneous changes.

  As described above, in the fifth embodiment, the weight function calculation unit 35 of the handover control server 3 sets the peak bit rate, the average bit rate, and the minimum bit rate, which are communication quality information notified from the mobile device 1, as input parameters. Therefore, the handover destination cell can be selected in consideration of the current communication quality.

  In the fifth embodiment, the weight function calculation unit 35 of the handover control server 3 calculates a weight function including a term that uses the movement history of the cell to which the mobile device 1 has moved as an input parameter. The handover destination cell can be selected in consideration of the moving speed of the mobile device 1.

  Furthermore, in the fifth embodiment, the weight function calculation unit 35 of the handover control server 3 uses the radius of the neighboring cell and / or the maximum transmission power of the base station 2 that controls the neighboring cell as input parameters. Therefore, it is possible to exclude a neighboring cell in which a handover with communication quality degradation occurs from a handover destination cell.

  In the fifth embodiment, the weight function calculation unit 35 of the handover control server 3 uses the used frequency and / or the wireless access method as an input parameter from the wireless access method including the used frequency included in the network configuration information. Therefore, it is possible to exclude a neighboring cell in which a handover with communication quality degradation occurs from a handover destination cell.

  Further, since the weight function calculation unit 35 of the handover control server 3 calculates a weight function including a term calculated from the used resources measured by the base station 2, wireless resources and wired resources, and the base station 2 The handover destination cell can be determined in consideration of the buffering source and the CPU usage rate.

  As described above, the radio communication system according to the present invention is useful for radio communication systems in which radio resources to be used change according to radio channel quality, and in particular, a radio that performs handover according to the degree of measurement of radio channel quality. Suitable for communication systems.

1, 1a mobile station 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7 base station 3, 3a handover control server 4-1, 4-2, 4- 3 Edge routers 5-1 and 5-2 Router 6 Radio access network 7 Core network 8 IP network 9 Mobile network 10 Internet 11-1-1, 11-1-2, 11-1-3, 11-1-4, 11-1-5, 11-1-6, 11-2-1, 11-2-2, 11-2-3, 11-2-4, 11-2-5, 1-3-1, 11- 3-2, 11-3-3, 11-3-4, 11-3-5, 11-4-1, 11-4-2, 11-4-3, 11-4-4, 11-4- 5, 11-5-1, 11-5-2, 11-5-3, 11-5-4, 11-5-5, 11-5-6, 11-6-1, 11- -2, 11-6-3, 11-6-4, 11-6-5, 11-6-6, 11-7-1, 11-7-2, 11-7-3, 11-7-4 Cell 12 Weight function storage unit 13 Peripheral cell list storage unit 14 Radio channel quality measurement unit 15 Peripheral cell selection parameter calculation / comparison unit 16 Peripheral cell selection determination unit 17 Radio channel transmission / reception unit 21, 31 Wired channel termination unit 22 Used resource measurement unit DESCRIPTION OF SYMBOLS 23 Radio | wireless line transmission / reception part 32 Base station communication control part 33 Mobile station communication control part 34 Cell list production | generation part 35 Weight function calculation part 36 Network configuration memory | storage part 37 Cell configuration memory | storage part 38 Use resource memory | storage part 39 Weight function verification part

Claims (1)

A plurality of base stations that control at least one cell and connect to a mobile station via a wireless line, a plurality of edge routers that accommodate at least one of the plurality of base stations, and at least one of these edge routers In a wireless communication system comprising a plurality of routers connected to a handover control server and a second network via a first network
The base station
A used resource measuring unit that measures a used resource for each cell controlled by the own station, and notifies the measured handover used resource to the handover control server;
A wireless communication system comprising:

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