Radio controller

Abstract

To secure radio resources of a radio base station by a forced handover while maintaining radio communication of a radio terminal that has been forcibly handed over.SOLUTION: If a radio base station 20(B) does not have radio resources to use for radio communication with a new radio terminal 30(X), a radio controller 10 secures radio resources for the radio base station 20(B) by forcibly handing over a fixed radio terminal 30(Y) that is installed at a predetermined location among radio terminals during radio communication with the radio base station 20(B) to another radio base station 20(C) adjacent to the radio base station 20(B).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a handover control technique for securing radio resources at a radio base station by forcibly handing over a radio terminal in communication with the radio base station to another radio base station. [Background technology]

[0002] Conventionally, as a technology for reserving radio resources at a radio base station, Patent Document 1 proposes a technology for reserving radio resources at the radio base station by forcibly handing over a radio terminal that is communicating with the radio base station to another radio base station.

[0003] According to this conventional technology, for example, when a handover request is made from a new wireless terminal to a wireless base station that has no available wireless resources, another wireless terminal that is communicating with the wireless base station can be forced to hand over to a wireless base station adjacent to the wireless base station. As a result, the wireless resources that the other wireless terminal used in the wireless base station becomes available in the wireless base station, and the new wireless terminal can be handed over to the wireless base station using these wireless resources. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2005 / 025253 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since there is a possibility that the other wireless terminal that has been forced to hand over may move afterwards, such conventional technology has the problem that, depending on the direction in which the other wireless terminal moves, it may move out of the wireless communication zone of the wireless base station to which it is handed over and become out of communication range.

[0006] For example, in the above example, if the direction of movement of the other wireless terminal is in the direction returning to the original wireless base station, the other wireless terminal will request handover to the original wireless base station, but the original wireless base station has insufficient radio resources and is unable to handover to the original wireless base station. Therefore, if the other wireless terminal continues to move, it may move out of the zone of the other wireless base station and fall out of the communication range, making it impossible to maintain wireless communication.

[0007] The present invention is made to solve such problems, and aims to provide a handover control technology that can secure radio resources of a radio base station through forced handover while maintaining radio communication of a radio terminal that has undergone forced handover. [Means for solving the problem]

[0008] In order to achieve this object, a radio control device according to the present invention comprises: a memory circuit configured to store, for each of a plurality of radio base stations, resource usage status of radio resources used by the radio base station for radio communication with a radio terminal; and a control circuit configured to control handover of radio terminals between the plurality of radio base stations by performing data communication with each of the plurality of radio base stations via a communication line. When handing over a first radio terminal to a first radio base station among the plurality of radio base stations, the control circuit is configured to check the resource usage status of the first radio base station, and if the first radio base station has the radio resources used for radio communication with the first radio terminal, hand over the first radio terminal to the first radio base station; and if the first radio base station does not have the radio resources used for radio communication with the first radio terminal, forcibly hand over a second radio terminal installed at a predetermined position among the radio terminals currently communicating with the first radio base station to a second radio base station adjacent to the first radio base station among the plurality of radio base stations, thereby securing the radio resources of the first radio base station and then hand over the first radio terminal to the first radio base station.

[0009] In addition, in one configuration example of the above-mentioned radio control device according to the present invention, the control circuit is configured to start radio communication between the second radio base station and the second radio terminal by beamforming during the forced handover.

[0010] In addition, in one configuration example of the radio control device according to the present invention, the second radio terminal is fixedly installed at a position where the radio zones of the first radio base station and the second radio base station overlap.

[0011] In addition, one configuration example of the above-mentioned radio control device according to the present invention is configured so that, after the control circuit has forced a handover of the second radio terminal, it sequentially checks the resource usage status of the first radio base station stored in the memory circuit, and when the first radio base station runs out of radio resources to be used for radio communication with the second radio terminal, it cancels the forced handover of the second radio terminal and hands over the second radio terminal to the first radio base station. [Effects of the Invention]

[0012] According to the present invention, it is possible to secure radio resources of a radio base station by performing a forced handover while maintaining radio communication of a radio terminal that has undergone a forced handover. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram showing the configuration of a radio control device according to this embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing the positional relationship between a wireless base station and a wireless terminal (before handover). [Figure 3] FIG. 3 is a sequence diagram showing the operation of the radio network controller according to the present embodiment. [Figure 4] FIG. 4 is an explanatory diagram showing the positional relationship between a wireless base station and a wireless terminal (after handover). DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, an embodiment of the present invention will be described with reference to the drawings. [Wireless control device] First, with reference to the block diagram of FIG. 1, a radio control device 10 according to an embodiment of the present invention will be described.

[0015] This radio control device 10 is composed of a server device such as a radio control device that controls a telephone system or PBX as a whole, and is connected to a higher-level communication network NW such as the Internet or a telephone network via a communication line L1, and is also connected to each of a plurality of radio base stations 20 via a communication line L2.By performing data communication with these radio base stations 20, it exchanges and connects radio terminals 30 connected to the radio base stations 20 via radio lines to the communication network NW, and is configured to control handover of radio terminals 30 between these radio base stations 20.

[0016] [Radio base station] The radio base station 20 (A, B, C) is configured to relay and connect the radio terminal 30 to the radio control device 10 by performing radio communication with the radio terminal 30 located within its coverage area via a radio line W. In addition, the radio base station 20 is configured to start new radio communication with the radio terminal 30 in response to a handover request from the radio terminal 30 that is currently communicating radio communication with another radio base station 20.

[0017] [Wireless terminal] The wireless terminal 30 is a general wireless terminal such as a cordless telephone terminal or a smartphone, and is configured to connect to a communication network NW or to perform data communication or voice calls with the wireless terminal 30.

[0018] The radio system 1 is constructed by the radio control device 10 and the radio base station 20. In this embodiment, for ease of understanding, an example will be described in which there are three radio base stations 20 connected to the radio control device 10, namely, radio base stations A, B, and C, but the present invention is not limited to this, and as long as there are two or more radio base stations 20 connected to the radio control device 10, the present invention can be applied in the same manner as described below.

[0019] [Principle of the present invention] The wireless terminals 30 that communicate wirelessly with the wireless base station 20 include not only wireless terminals that are intended to be carried around by a person, but also wireless terminals that are intended to be fixedly installed in a predetermined location. In particular, in rooms such as offices, where many electronic devices are used, electrical wiring and communication wiring tend to become complicated, and measures are being introduced to solve this problem by making communication wiring wireless.

[0020] Meanwhile, wireless base stations are beginning to introduce beamforming, which increases the directivity of radio waves in a specific direction. This allows for stable and high-speed wireless communication with wireless terminals located far away, and even wireless terminals located within the range of an adjacent wireless base station can maintain stable wireless communication. This makes it possible for fixedly located wireless terminals to handover between two different wireless base stations.

[0021] Generally, when a wireless system is constructed using multiple wireless base stations, the wireless zones of the wireless base stations are arranged so that they partially overlap in order to ensure stable handover of wireless terminals between the wireless base stations. Therefore, in an area where the wireless zones overlap, even a wireless terminal that is fixedly arranged can handover between two different wireless base stations.

[0022] The present invention focuses on the fact that there are wireless terminals that are fixedly installed at predetermined positions within the range of such wireless base stations, and that even wireless terminals that are fixedly installed at predetermined positions can be handed over between two different wireless base stations, and is configured to secure wireless resources for a wireless base station when the wireless base station does not have wireless resources to use for wireless communication with a new wireless terminal by forcibly handing over a fixed wireless terminal that is fixedly installed at a predetermined position among the wireless terminals currently communicating wirelessly with the wireless base station to another wireless base station adjacent to the wireless base station.

[0023] As a result, since the communication terminal to be forcibly handed over is a communication terminal fixedly installed at a predetermined position, the wireless terminal to which the forcible handover is performed does not move, and therefore, the wireless terminal does not move in the direction returning to the original wireless base station as described above, resulting in a situation in which wireless communication cannot be maintained.

[0024] Furthermore, by using beamforming for wireless communication or by using an area where the wireless zones of the wireless base station and other adjacent wireless base stations overlap, it is possible to stably maintain wireless communication for wireless terminals that are the target of forced handover, thereby making it possible to secure wireless resources without causing problems due to forced handover.

[0025] [Detailed configuration of this embodiment] Next, a detailed configuration of the radio control device 10 according to this embodiment will be described. As shown in the block diagram of FIG. 1, the radio control device 10 includes a network I / F 11, a communication I / F 12, a memory circuit 13, and a control circuit 14 as main circuit sections.

[0026] [Network I / F] The network I / F 11 is configured to relay and connect the communication network NW and the control circuit 14 by performing data communication with the communication network NW via the communication line L1.

[0027] [Communication I / F] The communication I / F 12 is configured to relay the connection between the control circuit 14 and the wireless base station 20 by performing data communication with the wireless base station 20 via the communication line L2.

[0028] [Memory circuit] The memory circuit 13 is generally made up of a storage device such as a semiconductor memory or a hard disk, and is configured to store various processing data and programs used in the handover control process in the control circuit 14.

[0029] The main processing data stored in the memory circuitry 13 is resource usage status indicating the usage status of radio resources in each of the radio base stations 20. This resource usage status is sequentially acquired from each of the radio base stations 20 by the control circuitry 14 and stored in the memory circuitry 13. The program is a program that realizes handover control processing by cooperating with the CPU of the control circuitry 14, and is read from an external device or a recording medium (neither of which is shown) and stored in the memory circuitry 13 in advance.

[0030] [Control circuit] The control circuit 14 has a CPU and its peripheral circuits, and is configured to control handover of the wireless terminal 30 between the wireless base stations 20 by making the CPU and the program in the memory circuit 13 work together.

[0031] Specifically, when the control circuit 14 hands over the first wireless terminal to a first wireless base station among the wireless base stations 20, the control circuit 14 is configured to check the resource usage status of the first wireless base station stored in the memory circuit 13, and if the first wireless base station has the wireless resources to be used for wireless communication with the first wireless terminal, to hand over the first wireless terminal to the first wireless base station.

[0032] Furthermore, when the first radio base station does not have the radio resources to be used for radio communication with the first radio terminal, the control circuit 14 is configured to forcibly hand over a second radio terminal, which is fixedly installed at a predetermined location among the radio terminals currently communicating with the first radio base station, to a second radio base station among the multiple radio base stations that is adjacent to the first radio base station, thereby securing the radio resources of the first radio base station and then hand over the first radio terminal to the first radio base station.

[0033] In this case, in order to enable the second wireless terminal fixedly placed at a predetermined position to perform handover between the first and second wireless base stations, the control circuit 14 may be configured to start wireless communication between the second wireless base station and the second wireless terminal by beamforming during forced handover.

[0034] Alternatively, the control circuit 14 may be configured to select a wireless terminal that is fixedly installed at a predetermined location where the wireless zones of the first and second wireless base stations overlap as the second wireless terminal and perform a forced handover to the second wireless base station.

[0035] In addition, the control circuit 14 may be configured to, after forcibly handing over the second wireless terminal, sequentially check the resource usage status of the first wireless base station stored in the memory circuit, and if the first wireless base station runs out of wireless resources to be used for wireless communication with the second wireless terminal, cancel the forced handover of the second wireless terminal and hand over the second wireless terminal to the first wireless base station.

[0036] As a result, the second wireless terminal that is the target of the forced handover starts wireless communication with the first wireless base station, which is the original connection destination, thereby enabling effective use of the wireless resources of the second wireless base station, which is the destination of the forced handover.

[0037] [Operation of this embodiment] Next, the operation of the radio control device 10 according to this embodiment will be described.

[0038] Generally, when a wireless system is constructed using multiple wireless base stations, the wireless zones of the wireless base stations are arranged so that they partially overlap in order to ensure stable handover of wireless terminals between the multiple wireless base stations.

[0039] Fig. 2 is an explanatory diagram showing the positional relationship between wireless base stations and wireless terminals (before handover). In the following explanation, it is assumed that wireless base stations A, B, and C are arranged in the positional relationship shown in Fig. 2, and that the wireless zones ZA, ZB, and ZC of the wireless base stations A, B, and C partially overlap, and that a mobile wireless terminal X is in wireless communication with the wireless base station A, a wireless terminal Y fixedly installed at a predetermined position is in wireless communication with the wireless base station B, and a mobile wireless terminal Z is in wireless communication with the wireless base station C.

[0040] 3, when wireless terminal X is moving from wireless zone ZA toward wireless base station B and enters wireless zone ZB where the radio wave intensity from wireless base station B is stronger than that from wireless base station A, wireless terminal X transmits a handover permission request (HO permission request) requesting a handover of wireless base station B to wireless base station A (step 100). Wireless base station A transfers the handover permission request from wireless terminal X to the wireless control device 10 via communication line L2.

[0041] The control circuit 14 of the radio control device 10 receives a handover permission request from the radio terminal X via the communication I / F 12, and obtains and confirms the resource usage status of the radio base station B designated as the handover destination from the memory circuit 13 (step 101).

[0042] Here, if the wireless base station B does not have the wireless resources to be used for wireless communication with the wireless terminal X, the control circuit 14 selects the wireless terminal Y as a fixed wireless terminal that is fixedly installed at a predetermined location among the wireless terminals currently communicating wirelessly with the wireless base station B (step 102), and selects the wireless base station C as a forced handover destination that can communicate wirelessly with the wireless terminal Y (step 103).

[0043] The fixed wireless terminals may be listed in advance for each wireless base station 20 and stored in the storage circuitry 13, or a list of the fixed wireless terminals located under the wireless base station B designated as the handover destination may be acquired from the wireless base station B. In addition, the forced handover destinations may be listed in advance for each fixed wireless terminal and stored in the storage circuitry 13.

[0044] Thereafter, the control circuit 14 acquires and checks the resource usage status of the wireless base station C from the memory circuit 13, and if the wireless base station C has wireless resources to be used for wireless communication with the wireless terminal Y, it transmits a terminal pick-up request for the wireless terminal Y from the communication I / F 12 to the wireless base station C via the communication line L2 (step 104). At this time, if the wireless base station C does not have wireless resources to be used for wireless communication with the wireless terminal Y, the wireless terminal Y and the wireless base station C are reselected in steps 102 and 103.

[0045] When the wireless base station C receives the terminal takeover request from the wireless control device 10, it starts beamforming for the wireless terminal Y (step 105).

[0046] Meanwhile, the control circuit 14 transmits a terminal movement instruction indicating a forced handover of the wireless terminal Y to the wireless base station C from the communication I / F 12 to the wireless base station B via the communication line L2 (step 110). The wireless base station B transfers the terminal movement instruction from the wireless control device 10 to the wireless terminal Y.

[0047] In response to a terminal movement instruction from the radio control device 10, the radio terminal Y transmits a handover request (HO request) to the radio base station C (step 111), and in response to a handover permission (HO permission) returned from the radio base station C (step 112), starts radio communication with the radio base station C (step 113) and terminates radio communication with the radio base station B.

[0048] In response to the start of wireless communication with the wireless terminal Y, the wireless base station C returns a terminal takeover response indicating the completion of the forced handover to the wireless control device 10 via the communication line L2 (step 114).

[0049] In response to the terminal takeover response indicating the completion of the forced handover from the wireless base station C, the control circuit 14 of the wireless control device 10 returns a handover permission response (HO permission response) from the communication I / F 12 to the wireless base station A via the communication line L2 (step 120). The wireless base station A transfers the handover permission response (HO permission response) from the wireless control device 10 to the wireless terminal X.

[0050] In response to the handover permission response (HO permission response) from the radio control device 10, the radio terminal X transmits a handover request (HO request) to the radio base station B (step 121), and in response to the return of the handover permission (HO permission) from the radio base station B (step 122), starts wireless communication with the radio base station B (step 123) and terminates wireless communication with the radio base station A.

[0051] As a result, as shown in Figure 4, wireless terminal Y, which is a fixed wireless terminal that was in wireless communication with wireless base station B, enters wireless communication with wireless base station C by beamforming BF, and wireless communication between wireless base station B and wireless terminal X is started using the wireless resources secured by the forced handover of wireless terminal Y.

[0052] In addition, after performing a forced handover, the control circuit 14 may sequentially check the resource usage status of the wireless base station B, which is the source of the forced handover and is stored in the memory circuit 13, and if wireless resources to be used for wireless communication with the wireless terminal Y, which is the target of the forced handover, become available in the wireless base station B, the forced handover of the wireless terminal Y may be canceled and the wireless terminal Y may be handed over to the original wireless base station B.

[0053] This allows beamforming at the radio base station C, which is the forced handover destination, to be stopped, and makes it possible to effectively use the radio resources of the radio base station C.

[0054] In the above explanation, an example has been given in which the control circuit 14 initiates wireless communication between the second wireless base station and the second wireless terminal by beamforming during forced handover, so that the fixedly placed wireless terminal Y can perform handover between base stations, but the present invention is not limited to this.

[0055] For example, the control circuit 14 may be configured to select a wireless terminal that is fixedly installed at a location where the wireless zones ZB and ZC of wireless base stations B and C overlap as wireless terminal Y, and to forcibly hand over this wireless terminal Y from wireless base station B to wireless base station C.

[0056] [Advantages of this embodiment] In this way, in this embodiment, when the radio base station 20(B) does not have radio resources to use for radio communication with a new radio terminal 30(X), the radio control device 10 is configured to forcibly hand over the fixed radio terminal 30(Y), which is a fixedly installed radio terminal among the radio terminals currently communicating radio with the radio base station 20(B), to another radio base station 20(C) adjacent to the radio base station 20(B), thereby securing radio resources for the radio base station 20(B).

[0057] Specifically, in this case, in order to enable the fixed wireless terminal 30(Y) to perform handover between the wireless base station 20(B) and another adjacent wireless base station 20(C), the wireless control device 10 may be configured to start wireless communication between the other wireless base station 20(C) and the fixed wireless terminal 30(Y) by beamforming during forced handover.

[0058] Alternatively, the radio control device 10 may be configured to select a radio terminal that is fixedly installed at a location where the radio zones of these radio base stations 20 (B, C) overlap as a radio terminal (Y) and perform a forced handover to another radio base station 20 (C).

[0059] As a result, since the communication terminal to be forcibly handed over is a fixed communication terminal, the wireless terminal that has been forcibly handed over does not move. Therefore, the wireless terminal does not move in the direction returning to the original wireless base station as described above, resulting in a situation where wireless communication cannot be maintained, and the wireless communication of the wireless terminal that has been forcibly handed over can be stably maintained by beamforming. It is possible to secure wireless resources without causing problems due to forced handover.

[0060] [Extended embodiment] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. [Explanation of symbols]

[0061] 1...wireless system, 10...wireless control device, 11...network I / F, 12...communication I / F, 13...memory circuit, 14...control circuit, 20, A, B, C...wireless base station, 30, X, Y, Z...wireless terminal, BF...beamforming, L1, L2...communication line, NW...communication network.

Claims

1. a memory circuit configured to store, for each of a plurality of radio base stations, a resource usage status of a radio resource used by the radio base station for radio communication with a radio terminal; a control circuit configured to control handover of a wireless terminal between the plurality of wireless base stations by performing data communication with each of the plurality of wireless base stations via a communication line; Equipped with The control circuit when handing over a first radio terminal to a first radio base station among the plurality of radio base stations, checking a resource usage status of the first radio base station, and when the first radio base station has radio resources to be used for radio communication with the first radio terminal, handing over the first radio terminal to the first radio base station; When the first radio base station does not have radio resources to be used for radio communication with the first radio terminal, a second radio terminal that is installed at a predetermined position among the radio terminals that are in radio communication with the first radio base station is forcibly handed over to a second radio base station that is adjacent to the first radio base station among the plurality of radio base stations, thereby securing radio resources of the first radio base station and then handing over the first radio terminal to the first radio base station. Radio control device.

2. The control circuit During the forced handover, the second wireless base station and the second wireless terminal start wireless communication by beamforming. The wireless control device according to claim 1 .

3. The second wireless terminal The first wireless base station and the second wireless base station are fixedly installed at a position where the wireless zones of the first wireless base station and the second wireless base station overlap. The wireless control device according to claim 1 .

4. The control circuit After the second wireless terminal is forcibly handed over, the resource usage status of the first wireless base station stored in the storage circuit is successively checked, and when the first wireless base station runs out of wireless resources to be used for wireless communication with the second wireless terminal, the forced handover of the second wireless terminal is canceled and the second wireless terminal is handed over to the first wireless base station. The wireless control device according to any one of claims 1 to 3.

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