Telephone system, telephone controller, slave unit of telephone system, and handover control method

Abstract

To reduce power consumption of a slave unit by reducing a handover frequency by suppressing unnecessary handovers.SOLUTION: A slave unit 40 comprises a slave unit control section 46 comprising a handover processing section 46C that on the basis of radio wave intensity of respective master units 30 acquired by a radio wave intensity acquisition section 46B and when a new master unit having radio field intensity higher than that of an in-connection master unit in radio connection with the slave unit is detected, holds a handover to the new master unit in the case of the new master unit differing from a movement destination master unit stored in plan data 45A in a slave unit storage section 45 and performs a handover to the movement destination master unit when the radio field intensity of the movement destination master unit has reached a first threshold level after starting the holding.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a handover control technique used when a slave unit hands over between master units of a plurality of cordless telephones.

Background Art

[0002] In a telephone system in which a plurality of cordless telephones are connected to a telephone network in a switched manner, when a slave unit moves to an area where a master unit of each cordless telephone is installed, based on the radio wave intensity of the master unit located around measured by the slave unit, there is a device that has a function of seamlessly continuing the wireless communication of the slave unit by performing handover (H / O: Hand Over) to select and switch the master unit that becomes the wireless connection destination of the slave unit.

[0003] In general handover control, the radio wave intensity (RSSI: Received Signal Strength Indicator) of the master unit located around is constantly detected by the slave unit. When a new master unit with a higher radio wave intensity than the currently connected master unit is detected, the wireless connection destination of the slave unit is switched from the currently connected master unit to the new master unit. However, constantly detecting the radio wave intensity consumes a lot of power, so the battery of the slave unit is depleted quickly, and the operable time of the slave unit is shortened.

[0004] For this reason, as described in Patent Document 1, a technique has been proposed in which the radio wave intensity is not constantly detected, and the radio wave intensity of the master unit located around the slave unit is detected only when the radio wave intensity of the currently connected master unit falls below a threshold value. As a result, the frequency of detecting the radio wave intensity of the master unit is reduced, the power consumption can be reduced, and as a result, the operable time of the slave unit can be extended.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In general handover control, after detecting the radio wave intensity of the master unit located around the slave unit, as a basic operation, the master unit with the highest radio wave intensity is selected as a new connection destination and handover is performed. The same applies to the technology described in Patent Document 1. On the other hand, each master unit is arranged so that their communication areas overlap to a certain extent, and as the slave unit moves, the master unit with the highest radio wave intensity changes sequentially. Therefore, according to the above-described conventional technology, there is a problem that the frequency of handover increases and a large amount of power is consumed, so the battery of the slave unit is consumed quickly and the operable time of the slave unit becomes short.

[0007] The present invention is for solving such problems, and an object thereof is to provide a handover technique capable of reducing power consumption of a slave unit by suppressing unnecessary handovers and reducing the frequency of handovers.

Means for Solving the Problems

[0008] In order to achieve such an object, a telephone system according to the present invention is a telephone system that exchanges and connects a plurality of cordless telephones to a telephone network. Each of the slave units of the plurality of cordless telephones acquires the radio wave intensity regarding the master units of the plurality of cordless telephones, and is configured to control handover to select and switch a master unit to be a wireless connection destination based on the obtained radio wave intensity. A slave unit control unit, and a slave unit storage unit configured to store a destination master unit that is a moving destination of the slave unit among the master units. When a new master unit having a higher radio wave intensity than the connected master unit wirelessly connected to the slave unit is detected based on the radio wave intensity, the slave unit control unit stores the new master unit in the slave unit storage unit. When it is different from the destination master unit to be stored, the handover to the new master unit is suspended, and when the radio wave intensity of the destination master unit reaches a first threshold level after the suspension is started, the handover is performed to the destination master unit. It is configured.

[0009] In addition, in one configuration example of the telephone system according to the present invention, when a predetermined hold allowable period has elapsed since the start of the hold, the handset control unit is configured to perform a handover to the base station having the highest radio wave intensity at that time.

[0010] In addition, in one configuration example of the telephone system according to the present invention, when the radio wave intensity of the connected base station falls below a second threshold level after the start of the hold, the handset control unit is configured to perform a handover to the base station having the highest radio wave intensity at that time.

[0011] In addition, in one configuration example of the telephone system according to the present invention, the handset storage unit is configured to store the scheduled arrival time at the destination, and when the new base station is different from the destination base station, if the detection time when the new base station is detected is earlier than the time obtained by going back a predetermined time from the scheduled arrival time, the handset control unit is configured not to perform the hold and to perform a handover to the new base station.

[0012] In addition, a telephone control device according to the present invention is a telephone control device that exchanges and connects a plurality of cordless telephones to a telephone network. The telephone control device acquires the radio wave intensity regarding the base stations of the plurality of cordless telephones detected by the handsets of the plurality of cordless telephones, selects a base station to be the wireless connection destination of the handset based on the radio wave intensity, and is configured to instruct the handset to perform a handover to switch the wireless connection destination. The telephone control device includes a storage unit that stores a destination base station, which is the destination of the handset among the base stations. When a new base station having a higher radio wave intensity than the connected base station that is wirelessly connected to the handset is detected based on the radio wave intensity, the control unit holds the handover to the new base station when the new base station is different from the destination base station stored in the storage unit, and when the radio wave intensity of the destination base station rises to a first threshold level after the start of the hold, the control unit is configured to instruct the handset to perform a handover to the destination base station.

[0013] In addition, the handset of the telephone system according to the present invention is a handset of a telephone system that exchanges and connects a plurality of cordless telephones to a telephone network. Each of the handsets of the plurality of cordless telephones acquires the radio wave intensity related to the base unit of the plurality of cordless telephones, and is configured to control a handover that selects and switches the base unit to be the wireless connection destination based on the obtained radio wave intensity. It includes a handset control unit and a handset storage unit configured to store the destination base unit to which the handset will move among the base units. When a new base unit with a higher radio wave intensity than the connected base unit that is wirelessly connected to the handset is detected based on the radio wave intensity, the handset control unit holds the handover to the new base unit when the new base unit is different from the destination base unit stored in the handset storage unit. When the radio wave intensity of the destination base unit reaches the first threshold level after the start of the hold, it is configured to perform a handover to the destination base unit.

[0014] In addition, the handover control method according to the present invention is a handover control method used in a telephone system that exchanges and connects a plurality of cordless telephones to a telephone network and is executed by the handsets of the plurality of cordless telephones. The handsets of the plurality of cordless telephones include a handset control unit and a handset storage unit. The handset control unit acquires the radio wave intensity related to the base units of the plurality of cordless telephones, and a handset control step of controlling a handover that selects and switches the base unit to be the wireless connection destination based on the obtained radio wave intensity, and the handset storage unit stores the destination base unit to which the handset will move among the base units. The handset control step includes a first handset control step of holding the handover to the new base unit when a new base unit with a higher radio wave intensity than the connected base unit that is wirelessly connected to the handset is detected based on the radio wave intensity and the new base unit is different from the destination base unit stored in the handset storage unit, and a second handset control step of performing a handover to the destination base unit when the radio wave intensity of the destination base unit rises to the first threshold level after the start of the hold.

[0015] The handover control method according to the present invention is a handover control method executed by a telephone control device that exchanges and connects a plurality of cordless telephones to a telephone network. The telephone control device includes a control unit and a storage unit. The control unit acquires the radio wave intensity related to the master unit of the plurality of cordless telephones detected by the slave unit of the plurality of cordless telephones, selects the master unit that will be the wireless connection destination of the slave unit based on the radio wave intensity, and instructs the slave unit to perform a handover to switch the wireless connection destination. The storage unit stores the destination master unit to which the slave unit will move among the master units. The control step includes a first control step of suspending the handover to the new master unit when a new master unit with a higher radio wave intensity than the currently connected master unit to which the slave unit is wirelessly connected is detected based on the radio wave intensity, and when the new master unit is different from the destination master unit stored in the storage unit; and a second control step of instructing the slave unit to perform a handover to the destination master unit when the radio wave intensity of the destination master unit rises to a first threshold level after the suspension starts.

Effect of the Invention

[0016] According to the present invention, it is possible to suppress unnecessary handovers, reduce the frequency of handovers, and reduce the power consumption of the slave unit.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0018] Next, embodiments of the present invention will be described with reference to the drawings. [First Embodiment] First, with reference to FIG. 1, a telephone system according to the first embodiment of the present invention will be described. As shown in the block diagram of FIG. 1, this telephone system 1 includes a telephone control device 10 connected to a general telephone network NW such as a public switched telephone network (PSTN) or an IP telephone network via a telephone line L, and a plurality of cordless telephones 20 internally connected to the telephone control device 10 via an internal line D.

[0019] [Telephone Control Device] The telephone control device 10 generally consists of a server device such as a main device of a push-button telephone system or a PBX device of a PBX system, and is configured to exchange-connect each cordless telephone 20 to the telephone network NW and to exchange-connect between each cordless telephone 20. In the present embodiment, the case where only the cordless telephones 20 are internally connected to the telephone control device 10 will be described as an example, but the present invention is not limited thereto. For example, even when other internal telephones such as push-button telephones are internally connected to the telephone control device 10, the present invention can be applied and the same operational effects as those of the present invention can be obtained.

[0020] [Cordless Telephone] The cordless telephone 20 includes a master unit 30 connected to the telephone control device 10 via an internal line D, and a slave unit 40 connected to the master unit 30 via a wireless line W. [Master Unit] The master unit 30 is configured to relay-connect the slave unit 40 connected via the wireless line W to the telephone control device 10 via the internal line D. [Slave Unit] The slave unit 40 is configured to be relayed and connected to the telephone control device 10 via the wireless line W and the internal line D, and to perform a voice call using the telephone network NW.

[0021] [Principle of the present invention] Generally, some cordless telephones 20 have a function of storing data regarding the destination of the slave unit 40. For example, when a user registers a schedule regarding a meeting attended by the slave unit 40, the meeting location is registered. Also, in the telephone control device 10, the installation position of the master unit 30 is managed, and since it is possible to identify the master unit closest to the meeting location, the user can easily identify the destination master unit during the movement for attending the meeting. On the other hand, when detecting the radio wave intensity of the master unit 30 located around the slave unit 40, selecting the master unit with the highest radio wave intensity as the handover destination is an effective measure for obtaining good communication quality with the slave unit 40 after the handover. However, even if it is not the highest radio wave intensity, it is possible to obtain a certain communication quality with the slave unit 40 if it is the radio wave intensity at the threshold level.

[0022] The present invention focuses on the fact that when the destination master unit of the slave unit 40 is specified, it is possible to determine whether or not the radio wave intensity of the destination master unit has reached the threshold level. Even if a new master unit with a higher radio wave intensity than the currently connected master unit is detected, if the new master unit is different from the destination master unit, the handover to the new master unit is postponed. If the radio wave intensity of the destination master unit reaches the threshold level after the start of the postponement, the handover is performed to the destination master unit. Thereby, since the handover to the destination master unit is prioritized, it is possible to suppress unnecessary handovers to new master units other than the destination master unit, and by reducing the frequency of handovers, it is possible to reduce the power consumption of the slave unit 40.

[0023] [Configuration of the present embodiment] Next, with reference to FIG. 1, the configuration of the present embodiment will be described. [Slave unit] The slave unit 40 is configured to control a handover that acquires the radio wave intensity of the master unit 30 located around it and selects and switches the master unit 30 to be the wireless connection destination based on the acquired radio wave intensity. The slave unit 40 includes a slave unit control unit 46 and a slave unit storage unit 45 configured to store the destination master unit to which the slave unit 40 will move among the master units 30.

[0024] When a new master unit with a higher radio wave intensity than the connected master unit wirelessly connected to the slave unit 40 is detected based on the radio wave intensity, the slave unit control unit 46 holds the handover to the new master unit when the new master unit is different from the destination master unit stored in the slave unit storage unit 45. When the radio wave intensity of the destination master unit reaches the threshold level after the start of the hold, the slave unit control unit 46 is configured to perform a handover to the destination master unit.

[0025] In the present embodiment, the configuration in which the slave unit control unit 46 performs the handover control of the slave unit 40 will be described. However, a configuration in which the telephone control device 10 performs the handover control of each slave unit 40 is also possible. As shown in FIG. 1, the telephone control device 10 includes a control unit 14 that performs call control of each cordless telephone 20 and a storage unit 13 that stores processing data such as call control information. The control unit 14 and the storage unit 13 may be configured in the same manner as the slave unit control unit 46 and the slave unit storage unit 45. Details of this configuration will be described in the second embodiment.

[0026] [Slave unit] Next, with reference to FIG. 2, the configuration of the slave unit 40 of the cordless telephone 20 according to the present embodiment will be described in detail. As shown in the block diagram of FIG. 2, the slave unit 40 includes, as main circuit units, a wireless I / F 41, a call unit 42, a display unit 43, an operation unit 44, a slave unit storage unit 45, and a slave unit control unit 46. In the telephone system 1 of the present invention, the slave unit 40 can be wirelessly connected to the master unit 30 of each cordless telephone 20 internally connected to the telephone control device 10, and is configured to be able to hand over the connection destination master unit 30 as the slave unit 40 moves.

[0027] [Wireless I / F] The wireless I / F 41 is configured to transmit and receive various data such as call control data and voice data by performing wireless communication with the master unit 30 via the wireless line W. Further, the wireless I / F 41 is configured to detect the radio wave intensity (RSSI) of the radio wave transmitted from the master unit 30 located in the vicinity and notify the slave unit control section 46.

[0028] [Call section] The call section 42 is configured to perform encoding and decoding processes of voice used for voice calls. [Display section] The display section 43 is configured to visibly display the operating state of the slave unit 40 using an LCD or an LED. [Operation section] The operation section 44 is configured to detect the user's operation and output it to the slave unit control section 46.

[0029] [Slave unit memory section] The slave unit memory section 45 consists of a storage device such as a semiconductor memory, and is configured to store various processing data and a program 45P used for the processing operation of the slave unit control section 46. The program 45P is a program that realizes various processing sections including handover control by cooperating with the CPU of the slave unit control section 46, and is read from an external device or a recording medium (both not shown) and stored in advance in the slave unit memory section 45.

[0030] As the main processing data stored in the slave unit memory section 45, there is schedule data 45A. The schedule data 45A is data indicating the schedule of the user who uses the slave unit 40, and data such as the scheduled location and scheduled date and time are registered for each schedule. When the user carries the slave unit 40 and moves to the scheduled location, the scheduled location in the schedule data 45A becomes the destination, and the scheduled date and time becomes the scheduled arrival time at the destination.

[0031] In addition, the scheduled data 45A also registers the identification information of the master unit closest to the scheduled location, i.e., the destination, which is the destination master unit. Regarding the destination master unit, it may be specified based on the installation positions of the respective master units 30 managed by the telephone control device 10. At the time of registering the scheduled data 45A, the slave unit control unit 46 may notify the telephone control device 10 of the scheduled location and acquire the identification information of the destination master unit corresponding to the scheduled location.

[0032] [Slave unit control unit] The slave unit control unit 46 has a CPU and its peripheral circuits, and is configured to realize a processing unit used for various operations of the slave unit 40 by reading out the program 45P of the slave unit storage unit 45 and cooperating with the CPU. The main processing units realized by the slave unit control unit 46 include a call control unit 46A, a radio wave intensity acquisition unit 46B, and a handover processing unit 46C.

[0033] [Call control unit] The call control unit 46A is configured to control operations related to voice calls on the slave unit 40 such as incoming and outgoing calls by exchanging call control messages with the master unit 30 via the wireless line W. [Radio wave intensity acquisition unit] The radio wave intensity acquisition unit 46B is configured to acquire the radio wave intensity related to the radio waves from each master unit 30 located around the slave unit measured by the wireless I / F 41.

[0034] [Handover processing unit] When a new master unit with a higher radio wave intensity than the connected master unit wirelessly connected to the slave unit 40 is detected based on the radio wave intensity of each master unit 30 acquired by the radio wave intensity acquisition unit 46B, the handover processing unit 46C holds the handover to the new master unit when the new master unit is different from the destination master unit stored in the scheduled data 45A of the slave unit storage unit 45, and when the radio wave intensity of the destination master unit reaches the first threshold level after the start of the hold, it is configured to perform a handover to the destination master unit.

[0035] Further, the handover processing unit 46C may be configured to perform a handover to the master unit with the highest radio wave intensity at that time when a predetermined hold allowable period has elapsed since the start of the hold. Further, the handover processing unit 46C may be configured to perform a handover to the master unit with the highest radio wave intensity at that time when the radio wave intensity of the connected master unit has fallen below the second threshold level after the start of the hold.

[0036] Further, when the new master unit is different from the destination master unit, the handover processing unit 46C checks the detection time when the new master unit is detected, and when the detection time is located before the movement start scheduled time that is a predetermined time back from the scheduled arrival time stored in the scheduled data 45A of the slave unit storage unit 45, the hold is not started and a direct handover is performed to the new master unit, and when the detection time is located after the movement start scheduled time, the hold may be configured to be started.

[0037] [Threshold level] In the present embodiment, two threshold levels, i.e., a first threshold level and a second threshold level, are used in the handover control. The first threshold level is a level indicating the radio wave intensity at which the master unit 30 and the slave unit 40 can perform wireless communication with a certain communication quality via the wireless line W. When the radio wave intensity of the master unit 30 measured by the slave unit 40 has risen to the first threshold level, the slave unit 40 is determined to be able to perform a handover to the master unit 30.

[0038] The second threshold level is a level indicating the radio wave intensity at which the master unit 30 and the slave unit 40 cannot perform wireless communication with a certain communication quality via the wireless line W. When the radio wave intensity of the connected master unit measured by the slave unit 40 has dropped to the second threshold level, the slave unit 40 is determined to need to perform a handover from the connected master unit to another master unit. These threshold levels may be different from each other or the same level, and are preset according to the operation mode and installation environment of the telephone system 1 and registered in the slave unit storage unit 45.

[0039] [Operation of the First Embodiment] Next, with reference to FIG. 3, as an operation of the present embodiment, handover control in the slave unit control unit 46 will be described. This handover control is executed each time the radio wave intensity acquisition unit 46B newly acquires the radio wave intensity of each master unit 30. Note that when the acquisition frequency of the radio wave intensity is high, the handover control may be configured to be executed at a cycle longer than the acquisition interval of the radio wave intensity.

[0040] As shown in the flowchart of FIG. 3, the radio wave intensity acquisition unit 46B of the slave unit control unit 46 acquires the radio wave intensity regarding the radio waves from each master unit 30 located around the slave unit newly measured by the wireless I / F 41 (step 100). The handover processing unit 46C of the slave unit control unit 46 compares the radio wave intensity of the currently connected master unit wirelessly connected to the slave unit 40 with the radio wave intensity of other master units based on the radio wave intensity of each master unit 30 newly acquired by the radio wave intensity acquisition unit 46B (step 101). Here, when no new master unit with a higher radio wave intensity than the currently connected master unit is detected (step 101: NO), the process returns to step 100.

[0041] On the other hand, when a new master unit with a higher radio wave intensity than the currently connected master unit is detected (step 101: YES), the handover processing unit 46C compares the new master unit with the destination master unit stored in the scheduled data 45A of the slave unit storage unit 45 (step 102). Here, when the new master unit matches the destination master unit (step 102: YES), the handover processing unit 46C hands over the wireless connection destination of the slave unit 40 from the currently connected master unit to the new master unit, that is, the destination master unit (step 103), and returns to step 100. Thereby, when wireless communication with the destination master unit becomes possible, it is possible to immediately hand over to the destination master unit, and unnecessary handovers can be suppressed.

[0042] On the other hand, in step 102, when the new master unit is different from the destination master unit (step 102: NO), the handover processing unit 46C holds the handover to the new master unit (step 104) and starts the pending processing (step 106) described later. Before starting the pending process, a necessity determination process (step 105) for determining the necessity of the pending process may be executed.

[0043] [Necessity determination process] In the necessity determination process of step 105, the handover processing unit 46C confirms the detection time when a new master device was detected in step 101, and calculates a movement start scheduled time that is retrogressed by a predetermined time from the arrival scheduled time stored in the scheduled data 45A of the slave device storage unit 45 (step 120).

[0044] Here, the handover processing unit 46C compares the detection time with the movement start scheduled time (step 121). When the detection time is before the movement start scheduled time (step 121: YES), the handover is not started and the device is immediately handed over to the new master device (step 122), and the process returns to step 100. On the other hand, when the detection time is after the movement start scheduled time (step 121: NO), the handover processing unit 46C starts the pending process described later.

[0045] [Pending process] In the pending process, the radio wave intensity acquisition unit 46B acquires the radio wave intensity regarding the radio waves from each master device 30 located around the slave device newly measured by the wireless I / F 41 (step 110). Based on the radio wave intensity of each master device 30 newly acquired by the radio wave intensity acquisition unit 46B, the handover processing unit 46C confirms the radio wave intensity of the destination master device and determines whether it has reached the first threshold level (step 111). Here, when the radio wave intensity of the destination master device has reached the first threshold level (step 111: YES), the handover processing unit 46C hands over the wireless connection destination of the slave device 40 from the connected master device to the destination master device (step 112), ends the pending process, and returns to step 100.

[0046] On the one hand, in step 111, when the radio wave intensity of the destination master device has not reached the first threshold level (step 111: NO), the handover processing unit 46C checks the radio wave intensity of the connected master device of the slave device 40 and determines whether it is below the second threshold level (step 113). Here, when the radio wave intensity of the connected master device is below the second threshold level (step 113: YES), the handover processing unit 46C hands over the wireless connection destination of the slave device 40 to the master device with the highest radio wave intensity at that time (step 114), terminates the suspended processing, and returns to step 100.

[0047] Also, in step 113, when the radio wave intensity of the connected master device is not below the second threshold level (step 113: NO), the handover processing unit 46C checks whether the suspended allowable period has elapsed since the start of suspension in step 110 (step 115). When the suspended allowable period has elapsed (step 115: YES), it proceeds to step 114 described above, hands over the wireless connection destination of the slave device 40 to the master device with the highest radio wave intensity at that time (step 114), terminates the suspended processing, and returns to step 100. Note that in step 114, when the suspended allowable period has not elapsed (step 115: NO), it returns to step 110.

[0048] Therefore, according to the present embodiment, as shown in the suspended processing, when wireless communication becomes possible with the destination master device after the start of suspension of handover, it is immediately handed over to the destination master device, so that unnecessary handover to a new master device with a higher radio wave intensity than the connected master device can be suppressed. Also, according to the present embodiment, when the communication quality of the wireless communication with the connected master device deteriorates after the start of suspension of handover, or when the suspended allowable period has elapsed, it is handed over to a new master device with a high radio wave intensity, so that the communication quality of the slave device 40 can be maintained.

[0049] Also, according to the present embodiment, as shown in the necessity determination process, when the detection time of detecting a new master unit is before the movement start scheduled time that is retrogressed by a predetermined time from the arrival scheduled time stored in the scheduled data 45A of the slave unit memory unit 45, handover to the new master unit is immediately performed without starting suspension, and when the detection time is after the movement start scheduled time, suspension is started. Thereby, it is possible to determine whether the user is moving according to the schedule registered in the scheduled data 45A, that is, the necessity of handover suppression. If it is before the movement start scheduled time, by stopping the handover suppression, it is possible to realize smooth handover control that does not give the user a sense of discomfort.

[0050] [Operation example of the first embodiment] Next, with reference to FIGS. 4 and 5, an operation example of the first embodiment will be described. In the explanatory diagram of FIG. 4, three master units P1, P2, P3 (30) are arranged such that their communication areas A1, A2, A3 overlap to some extent. Hereinafter, a case where the slave unit 40 moves from the communication area A1 of the master unit P1 to the communication area A3 of the master unit P3 via the communication area A2 of the master unit P2 along the movement route M will be described as an example. It is assumed that scheduled data 45A is registered in the slave unit 40 in advance, and the master unit P3 is registered as the destination master unit. Also, it is assumed that both the first threshold level and the second threshold level are equal to a certain one threshold level.

[0051] At time T1, the slave unit 40 is located within the area of the communication area A1, and the master unit P1 is the connected master unit. At this time, the slave unit 40 is not located within the area of other communication areas. When measuring the radio wave intensity, as shown in the graph of FIG. 5, the radio wave intensity R1 of the master unit P1 is the highest, and the radio wave intensities R2 and R3 of the other master units P2 and P3 are not measured. After that, when the slave device 40 moves in the direction of the master device P2 and reaches a position where the communication areas A1 and A2 overlap, the radio wave intensity R2 of the master device P2 gradually increases, and the radio wave intensity R1 of the master device P1 gradually decreases. When the radio wave intensity R2 exceeds the radio wave intensity R1 at time T2, according to the prior art, the connection destination of the slave device 40 is handed over from the master device P1 to the master device P2, but in this embodiment, the handover to the master device P2 is postponed.

[0052] After that, when the slave device 40 moves in the direction of the master device P3 and reaches a position where the communication areas A1, A2, and A3 overlap, the radio wave intensity R3 of the master device P3 gradually increases, and the radio wave intensities R1 and R2 of the master devices P1 and P2 gradually decrease. When the radio wave intensity R3 rises to the threshold level TH at time T3, the connection destination of the slave device 40 is handed over from the master device P1 to the master device P3, that is, the moving destination master device. Thereby, in this embodiment, a wasteful handover to the master device P2, which is different from the moving destination, is suppressed during the period from time T2 to time T3.

[0053] After that, when the slave device 40 further moves in the direction of the master device P3, the radio wave intensity R3 of the master device P3 gradually increases, and the radio wave intensities R1 and R2 of the master devices P1 and P2 gradually decrease. At time T4 when the slave device 40 moves outside the communication area A1, the radio wave intensity R1 falls below the threshold level TH, and the radio wave intensity R3 exceeds the radio wave intensity R2. Subsequently, at time T5 when the slave device 40 moves outside the communication area A2, the radio wave intensity R1 is not measured, the radio wave intensity R2 further decreases and falls below the threshold level TH, and the radio wave intensity R3 further increases.

[0054] Therefore, when the destination master device of the slave device 40 is unknown, the slave device is handed over to the master device with the highest radio wave intensity at each time. Thus, when the radio wave intensity changes as shown in FIG. 5, after handing over from the master device P1 to the master device P2 at time T2, it will be handed over from the master device P2 to the master device P3 at time T4. However, as shown in FIG. 4, the communication area A1 overlaps with the communication area A3, and actually, it is possible to directly hand over from the master device P1 to the master device P3, and it can be seen that the handover to the master device P2 is a wasteful handover.

[0055] According to the present embodiment, the destination master device of the slave device 40 is stored in the slave device storage unit 45. Even if a new master device P2 with a higher radio wave intensity than the currently connected master device P1 appears, since it is different from the destination master device P3, the handover to the master device P2 will be postponed. For this reason, during the period from the time T2 when the master device P2 appears to the time T3 when the destination master device P3 appears, the handover is postponed, and a wasteful handover to the master device P2 is suppressed. Then, at time T3, it will be directly handed over from the master device P1 to the destination master device P3.

[0056] [Effect of the First Embodiment] As described above, in the present embodiment, when the handover processing unit 46C of the slave device control unit 46 detects a new master device with a higher radio wave intensity than the currently connected master device to which the slave device 40 is wirelessly connected based on the radio wave intensity of each master device 30 acquired by the radio wave intensity acquisition unit 46B, if the new master device is different from the destination master device stored in the scheduled data 45A of the slave device storage unit 45, the handover to the new master device is postponed. When the radio wave intensity of the destination master device reaches the first threshold level after the start of the postponement, it is configured to hand over to the destination master device.

[0057] As a result, when wireless communication becomes possible with the destination master device after the start of the handover hold, the handover is immediately performed to the destination master device. Therefore, the handover to the destination master device is prioritized, and unnecessary handovers to new master devices other than the destination master device can be suppressed. Accordingly, it is possible to reduce the frequency of handovers and reduce the power consumption of the slave device 40.

[0058] Also, in the present embodiment, the handover processing unit 46C may be configured to perform a handover to the master device having the highest radio wave intensity at that time when a predetermined hold allowable period has elapsed since the start of the hold. Thereby, when the user is moving in a direction different from the destination master device registered in the schedule data 45A, the hold of the handover is automatically released and the handover is performed to a new master device with high radio wave intensity, so that the communication quality of the slave device 40 can be maintained.

[0059] Also, in the present embodiment, the handover processing unit 46C may perform a handover to the master device having the highest radio wave intensity at that time when the radio wave intensity of the connected master device has fallen below the second threshold level after the start of the hold. Thereby, when the communication quality with the connected master device deteriorates, the hold of the handover is automatically released and the handover is performed to a new master device with high radio wave intensity, so that the communication quality of the slave device 40 can be maintained.

[0060] [Second Embodiment] Next, with reference to FIG. 6, a second embodiment of the present invention will be described. In the first embodiment, the configuration in which the slave device control unit 46 performs handover control of its slave device 40 has been described. In the present embodiment, a configuration in which the telephone control device 10 performs handover control of each slave device 40 will be described.

[0061] [Telephone Control Device] As shown in the block diagram of FIG. 6, the telephone control device 10 includes a network I / F 11, an in-house line side I / F 12, a storage unit 13, and a control unit 14 as main circuit units.

[0062] [Network I / F] The network I / F 11 is configured to transmit and receive call control messages and voice data to and from the telephone network NW via the telephone line L. [Internal line side I / F] The internal line side I / F 12 is configured to transmit and receive call control messages and voice data to and from the master unit 30 of each cordless telephone 20 via the internal line D.

[0063] [Memory unit] The memory unit 13 consists of a storage device such as a semiconductor memory or a hard disk, and is configured to store various processing data and programs 13P used for the processing operations of the control unit 14. The program 13P is a program that realizes various processing units including handover control by cooperating with the CPU of the control unit 14, and is read from an external device or a recording medium (both not shown) and stored in advance in the memory unit 13.

[0064] The main processing data stored in the memory unit 13 is schedule data 13A. The schedule data 13A is data indicating the schedule of the user who uses each slave unit 40, and data such as the scheduled location and scheduled date and time are registered for each schedule. When the user carries the slave unit 40 and moves to the scheduled location, the scheduled location in the schedule data 13A becomes the destination, and the scheduled date and time becomes the scheduled arrival time at the destination.

[0065] In addition, the schedule data 13A also registers identification information of the destination master unit indicating the master unit installed closest to the scheduled location, that is, the destination. Regarding the destination master unit, it may be specified at the time of registration of the schedule data 13A based on the installation positions of the respective master units 30 managed by the telephone control device 10.

[0066] [Control unit] The control unit 14 has a CPU and its peripheral circuits, and is configured to realize processing units used for various operations of the slave unit 40 by reading the program 13P of the memory unit 13 and cooperating with the CPU. As the main processing units realized by the control unit 14, there are a call control unit 14A, a radio wave intensity acquisition unit 14B, and a handover processing unit 14C.

[0067] [Call Control Unit] The call control unit 14A is configured to control operations related to voice calls on the slave unit 40 such as incoming and outgoing calls by exchanging call control messages with each slave unit 40 via the internal line D and the radio line W. [Radio Wave Intensity Acquisition Unit] The radio wave intensity acquisition unit 14B is configured to acquire the radio wave intensity related to the radio waves from each master unit 30 located around the slave unit, which is measured by the radio I / F 41 of each slave unit 40.

[0068] [Handover Processing Unit] For each slave unit 40, when a new master unit with a higher radio wave intensity than the currently connected master unit to which the slave unit 40 is wirelessly connected is detected based on the radio wave intensity of each master unit 30 acquired by the radio wave intensity acquisition unit 14B, the handover processing unit 14C holds the handover to the new master unit when the new master unit is different from the destination master unit stored in the scheduled data 13A of the storage unit 13. When the radio wave intensity of the destination master unit reaches the first threshold level after the start of the hold, the handover processing unit 14C is configured to instruct the slave unit 40 to perform the handover to the destination master unit.

[0069] Also, the handover processing unit 14C may be configured to instruct the slave unit 40 to perform the handover to the master unit with the highest radio wave intensity at that time when a predetermined hold allowable period has elapsed since the start of the hold. Also, the handover processing unit 14C may be configured to instruct the slave unit 40 to perform the handover to the master unit with the highest radio wave intensity at that time when the radio wave intensity of the currently connected master unit drops below the second threshold level after the start of the hold.

[0070] Also, when the new master device is different from the destination master device, the handover processing unit 14C checks the detection time when the new master device is detected, and when the detection time is located before the movement start scheduled time that is obtained by going back a predetermined time from the arrival scheduled time stored in the scheduled data 13A of the storage unit 13, the handover to the new master device is immediately instructed to the slave device 40 without starting the suspension, and when the detection time is located after the movement start scheduled time, the suspension may be configured to be started.

[0071] [Threshold level] In the present embodiment, two threshold levels, a first threshold level and a second threshold level, are used in handover control. The first threshold level is a level indicating the radio wave intensity at which the master device 30 and the slave device 40 can perform wireless communication with a certain communication quality via the wireless line W. When the radio wave intensity of the master device 30 measured by the slave device 40 rises to the first threshold level, the slave device 40 is determined to be able to hand over to the master device 30.

[0072] The second threshold level is a level indicating the radio wave intensity at which the master device 30 and the slave device 40 cannot perform wireless communication with a certain communication quality via the wireless line W. When the radio wave intensity of the connected master device measured by the slave device 40 drops to the second threshold level, the slave device 40 is determined to need to hand over from the connected master device to another master device. These threshold levels may be different from each other or the same level, and are preset according to the operation mode and installation environment of the telephone system 1 and registered in the storage unit 13.

[0073] [Operation of the Second Embodiment] Next, with reference to FIG. 3 described above, as the operation of the present embodiment, the handover control in the control unit 14 will be described. This handover control is executed each time the radio wave intensity acquisition unit 14B newly acquires the radio wave intensity of each master device 30 by each slave device 40. When the acquisition frequency of the radio wave intensity is high, the handover control may be configured to be executed at a cycle longer than the acquisition interval of the radio wave intensity.

[0074] As shown in the flowchart of FIG. 3, the radio wave intensity acquisition unit 14B of the control unit 14 acquires the radio wave intensity regarding the radio waves from each master unit 30 located around the slave unit 40 newly measured by the slave unit 40 to be processed (step 100). The handover processing unit 14C of the control unit 14 compares the radio wave intensity of the connected master unit wirelessly connected to the slave unit 40 with the radio wave intensity of other master units based on the radio wave intensity of each master unit 30 of the slave unit 40 newly acquired by the radio wave intensity acquisition unit 14B (step 101). Here, if no new master unit with a higher radio wave intensity than the connected master unit is detected (step 101: NO), the process returns to step 100.

[0075] On the other hand, if a new master unit with a higher radio wave intensity than the connected master unit is detected (step 101: YES), the handover processing unit 14C compares the new master unit with the destination master unit of the slave unit 40 stored in the scheduled data 13A of the storage unit 13 (step 102). Here, if the new master unit matches the destination master unit (step 102: YES), the handover processing unit 14C hands over the wireless connection destination of the slave unit 40 from the connected master unit to the new master unit, that is, the destination master unit (step 103), and returns to step 100. Thereby, when wireless communication with the destination master unit becomes possible, it is possible to immediately hand over to the destination master unit and suppress unnecessary handovers.

[0076] On the other hand, in step 102, if the new master unit is different from the destination master unit (step 102: NO), the handover processing unit 14C holds the handover to the new master unit (step 104) and starts the suspended processing (step 106) described later. Note that before starting the suspended processing, a necessity determination process (step 105) for determining the necessity of the suspended processing may be executed.

[0077] [Necessity determination process] In the determination process of the necessity of step 104, the handover processing unit 14C checks the detection time when a new master device was detected in step 101, and calculates the scheduled start time of movement that is retrogressed by a predetermined time from the scheduled arrival time of the slave device 40, which is stored in the scheduled data 13A of the storage unit 13 (step 120).

[0078] Here, the handover processing unit 14C compares the detection time with the scheduled start time of movement (step 121). When the detection time is before the scheduled start time of movement (step 121: YES), the handover processing unit 14C does not start suspension and immediately hands over to the new master device (step 122), and returns to step 100. On the other hand, when the detection time is after the scheduled start time of movement (step 121: NO), the handover processing unit 14C starts the suspension processing described later.

[0079] [Suspension processing] In the suspension processing, the radio wave intensity acquisition unit 14B acquires the radio wave intensity regarding the radio waves from each master device 30 located around the slave device 40 newly measured by the slave device 40 (step 110). Based on the radio wave intensity of each master device 30 newly acquired by the radio wave intensity acquisition unit 14B, the handover processing unit 14C checks the radio wave intensity of the destination master device and determines whether it has reached the first threshold level (step 111). Here, when the radio wave intensity of the destination master device has reached the first threshold level (step 111: YES), the handover processing unit 14C hands over the wireless connection destination of the slave device 40 from the connected master device to the destination master device (step 112), ends the suspension processing, and returns to step 100.

[0080] On the other hand, in step 111, if the radio wave intensity of the destination master device has not reached the first threshold level (step 111: NO), the handover processing unit 14C checks the radio wave intensity of the connected master device of the slave device 40 and determines whether it is below the second threshold level (step 113). Here, if the radio wave intensity of the connected master device is below the second threshold level (step 113: YES), the handover processing unit 14C hands over the wireless connection destination of the slave device 40 to the master device with the highest radio wave intensity at that time (step 114), ends the pending processing, and returns to step 100.

[0081] Also, in step 113, if the radio wave intensity of the connected master device is not below the second threshold level (step 113: NO), the handover processing unit 14C checks whether the allowable pending period has elapsed since the start of the pending in step 110 (step 115). If the allowable pending period has elapsed (step 115: YES), it proceeds to step 114 described above, hands over the wireless connection destination of the slave device 40 to the master device with the highest radio wave intensity at that time (step 114), ends the pending processing, and returns to step 100. Note that in step 114, if the allowable pending period has not elapsed (step 115: NO), it returns to step 110.

[0082] Therefore, according to the present embodiment, as shown in the pending processing, when wireless communication becomes possible with the destination master device after the start of the handover suspension, it is immediately handed over to the destination master device, so that unnecessary handovers to a new master device with a higher radio wave intensity than the connected master device can be suppressed. Also, according to the present embodiment, when the communication quality of the wireless communication with the connected master device deteriorates or the allowable pending period has elapsed after the start of the handover suspension, it is handed over to a new master device with a high radio wave intensity, so that the communication quality of the slave device 40 can be maintained.

[0083] Also, according to the present embodiment, as shown in the necessity determination process, when the detection time at which a new master device is detected is before the movement start scheduled time that is retrogressed by a predetermined time from the arrival scheduled time stored in the scheduled data 13A of the storage unit 13, handover to the new master device is immediately performed without starting suspension, and when the detection time is after the movement start scheduled time, suspension is started. Thereby, it is possible to determine whether the user is moving according to the schedule registered in the scheduled data 13A, that is, the necessity of handover suppression. If it is before the movement start scheduled time, by stopping the handover suppression, it is possible to realize smooth handover control that does not give the user a sense of discomfort.

[0084] [Effects of the Second Embodiment] As described above, in the present embodiment, when the handover processing unit 14C of the control unit 14 detects a new master device having a higher radio wave intensity than the currently connected master device wirelessly connected to the slave device 40 based on the radio wave intensity of each master device 30 acquired from each slave device 40 by the radio wave intensity acquisition unit 14B, if the new master device is different from the destination master device stored in the scheduled data 13A of the storage unit 13, the handover to the new master device is suspended. When the radio wave intensity of the destination master device reaches the first threshold level after the suspension is started, the handover to the destination master device is configured to be instructed to the slave device 40.

[0085] Thereby, when wireless communication becomes possible with the destination master device after the start of suspension of handover, since the handover to the destination master device is immediately performed, the handover to the destination master device is prioritized, and unnecessary handovers to new master devices other than the destination master device can be suppressed. Therefore, it is possible to reduce the frequency of handovers and reduce the power consumption of the slave device 40.

[0086] In addition, in the present embodiment, when a predetermined hold allowable period has elapsed since the start of the hold, the handover processing unit 14C may be configured to instruct the slave unit 40 to perform a handover to the master unit having the highest radio wave intensity at that time. As a result, when the user is moving in a direction different from the destination master unit registered in the schedule data 13A, the hold of the handover is automatically released and the slave unit 40 is handed over to a new master unit with high radio wave intensity, so that the communication quality of the slave unit 40 can be maintained.

[0087] In addition, in the present embodiment, when the radio wave intensity of the connected master unit falls below the second threshold level after the start of the hold, the handover processing unit 14C may be configured to instruct the slave unit 40 to perform a handover to the master unit having the highest radio wave intensity at that time. As a result, when the communication quality with the connected master unit deteriorates, the hold of the handover is automatically released and the slave unit 40 is handed over to a new master unit with high radio wave intensity, so that the communication quality of the slave unit 40 can be maintained.

[0088] [Expansion of the Embodiment] As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments. Various changes 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. In addition, each embodiment can be arbitrarily combined and implemented within a non - conflicting range. In addition, in each of the above embodiments, a telephone system in which the slave unit 40 performs handover between the master units 30 of a plurality of cordless telephones 20 has been described as an example. However, the present invention is not limited to this. Since the above - described telephone control device 10, master unit 30, and slave unit 40 can be regarded as a base station control device, a radio base station, and a radio terminal, respectively, the present invention can also be applied to a radio system in which a radio terminal performs handover between a plurality of radio base stations.

Explanation of Reference Numerals

[0089] 1…Telephone system, 10…Telephone control device, 11…Network I / F, 12…Internal line side I / F, 13…Memory unit, 13A…Scheduled data, 13P…Program, 14…Control unit, 14A…Call control unit, 14B…Radio wave intensity acquisition unit, 14C…Handover processing unit, 20…Cordless telephone, 30, P1, P2, P3…Master unit, 40…Sub unit, 41…Wireless I / F, 42…Communication unit, 43…Display unit, 44…Operation unit, 45…Sub unit memory unit, 45A…Scheduled data, 45P…Program, 46…Sub unit control unit, 46A…Call control unit, 46B…Radio wave intensity acquisition unit, 46C…Handover processing unit, NW…Telephone network, L…Telephone line, D…Internal line, W…Wireless line, A1, A2, A3…Communication area, R1, R2, R3…Radio wave intensity, TH…Threshold level, M…Movement route.

Claims

1. A telephone system for switching and connecting a plurality of cordless telephones to a telephone network, Each of the handsets of the plurality of cordless telephones, A handset control unit configured to obtain a radio wave intensity regarding the base unit of the plurality of cordless telephones, and control a handover to select and switch a base unit to be a wireless connection destination based on the obtained radio wave intensity; A handset storage unit configured to store a destination base unit to which the handset will move among the base units, The handset control unit, When a new base unit with a higher radio wave intensity than the connected base unit wirelessly connected to the handset is detected based on the radio wave intensity, if the new base unit is different from the destination base unit stored in the handset storage unit, the handover to the new base unit is suspended, and when the radio wave intensity of the destination base unit reaches a first threshold level after the start of the suspension, it is configured to perform a handover to the destination base unit A telephone system characterized by this.

2. In the telephone system according to claim 1, The handset control unit is configured to perform a handover to the base unit with the highest radio wave intensity at that time when a predetermined hold allowable period has elapsed since the start of the hold. A telephone system characterized by this.

3. In the telephone system according to claim 1, The handset control unit is configured to perform a handover to the base unit with the highest radio wave intensity at that time when the radio wave intensity of the connected base unit falls below a second threshold level after the start of the hold. A telephone system characterized by this.

4. In the telephone system according to any one of claims 1 to 3, The handset storage unit is configured to store a scheduled arrival time at the destination, When the new master unit is different from the destination master unit, if the detection time when the new master unit is detected is earlier than the time obtained by going back a predetermined time from the scheduled arrival time, the sub-unit control unit is configured to perform handover to the new master unit without holding the call. A telephone system characterized by the above. Claim 5 A telephone control device for exchange-connecting a plurality of cordless telephones to a telephone network, The telephone control device includes a control unit configured to acquire radio wave intensity regarding the master unit of the plurality of cordless telephones from a slave unit of the plurality of cordless telephones, select a master unit to be a wireless connection destination based on the radio wave intensity, and instruct the slave unit to perform a handover for switching the wireless connection destination. A storage unit that stores a destination master unit that is a movement destination of the slave unit among the master units. The control unit, When a new master unit with a higher radio wave intensity than the currently connected master unit during wireless connection with the slave unit is detected based on the radio wave intensity, if the new master unit is different from the destination master unit stored in the storage unit, the handover to the new master unit is held. When the radio wave intensity of the destination master unit rises to a first threshold level after the start of the hold, the control unit is configured to instruct the slave unit to perform a handover to the destination master unit. A telephone control device characterized by the above. Claim 6 A slave unit of a telephone system for exchange-connecting a plurality of cordless telephones to a telephone network, Each of the slave units of the plurality of cordless telephones, A sub-unit control unit configured to acquire radio wave intensity regarding the master unit of the plurality of cordless telephones, select a master unit to be a wireless connection destination based on the obtained radio wave intensity, and control a handover for switching. A sub-unit storage unit configured to store a destination master unit that is a movement destination of the slave unit among the master units. The sub-unit control unit, When a new master unit with a higher radio wave intensity than the currently connected master unit wirelessly connected to the slave unit is detected based on the radio wave intensity, if the new master unit is different from the destination master unit stored in the slave unit memory unit, the handover to the new master unit is suspended. When the radio wave intensity of the destination master unit reaches the first threshold level after the suspension is started, it is configured to perform a handover to the destination master unit. A slave unit of a telephone system, characterized by the above.

7. A handover control method used in a telephone system that exchanges and connects a plurality of cordless telephones to a telephone network, and is executed by a slave unit of the plurality of cordless telephones. The slave units of the plurality of cordless telephones include a slave unit control unit and a slave unit memory unit. A slave unit control step in which the slave unit control unit acquires the radio wave intensity related to the master unit of the plurality of cordless telephones, and controls a handover to select and switch the master unit to be the wireless connection destination based on the obtained radio wave intensity. A slave unit memory step in which the slave unit memory unit stores a destination master unit that is the destination of movement of the slave unit among the master units. The slave unit control step includes: A first slave unit control step of suspending the handover to the new master unit when a new master unit with a higher radio wave intensity than the currently connected master unit wirelessly connected to the slave unit is detected based on the radio wave intensity, and the new master unit is different from the destination master unit stored in the slave unit memory unit. A second slave unit control step of performing a handover to the destination master unit when the radio wave intensity of the destination master unit rises to the first threshold level after the suspension is started. A handover control method, characterized by the above.

8. A handover control method executed by a telephone control device that exchanges and connects a plurality of cordless telephones to a telephone network. The telephone control device includes a control unit and a memory unit. The control unit obtains, from the slave units of the plurality of cordless telephones, the radio wave intensity regarding the master unit of the plurality of cordless telephones detected by the slave unit, selects the master unit to be the wireless connection destination of the slave unit based on the radio wave intensity, and instructs the slave unit to perform a handover to switch the wireless connection destination; The storage unit stores a destination master unit, which is the destination of movement of the slave unit, among the master units; and The control step includes: When a new master unit with a higher radio wave intensity than the connected master unit that is wirelessly connected to the slave unit based on the radio wave intensity is detected, a first control step of holding the handover to the new master unit when the new master unit is different from the destination master unit stored in the storage unit; A second control step of instructing the slave unit to perform a handover to the destination master unit when the radio wave intensity of the destination master unit rises to a first threshold level after the start of the hold; A handover control method characterized by the above.

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