JP7464902B2 - Telephone system, cordless telephone base unit and telephone control device - Google Patents

Description

This invention relates to a telephone system configured by connecting a cordless telephone device in which the base unit and handset are wirelessly connected to a telephone control device such as a main device or a SIP (Session Initiation Protocol) server, and to the base unit and telephone control device of the cordless telephone device used in the telephone system.

In recent years, business phone systems (button telephone systems) have come to be configured by connecting cordless telephone devices to telephone control devices such as main units and SIP servers. A cordless telephone device functions as a single telephone device with a base unit and handset wirelessly connected. For example, a communication method based on the DECT (Digital Enhanced Cordless Telecommunication) standard may be used between the base unit and handset that make up the cordless telephone device.

The DECT standard specifies that the communication method for the downlink from the parent unit to the child unit is time division duplex using time division multiplexing, and that the communication method for the uplink from the child unit to the parent unit is time division multiple access. The DECT standard also specifies that the frequency band to be used is the 1.9 GHz band, and that the maximum number of channels is 5.

In the DECT standard, one frame of coded data in one channel is 10 milliseconds (ms), and is divided into 24 time slots as shown in Figure 10. In the following, time slots will simply be referred to as slots. The 12 slots S0 to S11 in the first half frame period of one frame are used for downlink from the parent unit to the child unit, and the 12 slots S12 to S23 in the second half frame period are used for uplink from the child unit to the parent unit.

In DECT-standard cordless telephone devices used in business phone systems, unless the power is off, one cordless telephone device uses one of the 12 slots in standby (idle) to transmit various control information, including synchronization signals, from the base unit to the handset. The slot (control signal slot) used in this case is called a dummy bearer. Normally, multiple handsets can be connected to a base unit, but in standby, control information is transmitted to each handset using one slot (dummy bearer) whether only one handset is connected to the base unit or multiple handsets are connected. In this case, no information is transmitted from the handset to the base unit.

If, for example, an incoming call is received from this standby state and the parent unit is notified of the incoming call from the telephone control device, the parent unit uses a dummy bearer to notify each handset of a data session connection request, and the handset searches for an available slot and approaches the parent unit to attempt to acquire a slot to use for communication. The data session connection request is a request to create an environment in which the parent unit and handset can communicate with each other, and is not a notification of the incoming call. Then, when a slot for mutual communication between the parent unit and handset is acquired in response to the data session connection request, the parent unit releases the dummy bearer and notifies the parent unit of the incoming call using the acquired downlink slot. At the same time, the parent unit also identifies an uplink slot so that it can receive information from the handset.

In this way, the pair of downlink slots and uplink slots acquired for mutual communication between the parent and child devices is called a traffic bearer. Various control information, including synchronization signals, is transmitted through the traffic bearer, and after a call line is connected to the other end of the communication, voice information is also transmitted. Since various control information and the like is also transmitted through the traffic bearer, the process of identifying (obtaining) the traffic bearer and releasing the dummy bearer is called merging the dummy bearer into the traffic bearer.

In this way, in the process of merging a dummy bearer with a traffic bearer, there is a period during which the dummy bearer and traffic bearer are simultaneously acquired, which may narrow the range of slot selection. Therefore, Patent Document 1 described later discloses an invention related to a cordless telephone device that shortens the period during which the dummy bearer and traffic bearer are simultaneously acquired, appropriately secures free slots, and always appropriately processes incoming and outgoing calls to enable conversations without delay. The invention described in Patent Document 1 is effective in that it efficiently performs the process of merging a dummy bearer with a traffic bearer, shortens the period during which a slot is occupied by a dummy bearer, and enables efficient use of slots.

JP 2016-225927 A

However, when a handover is performed, in which a handset moves to change the parent device to which it is connected while in standby mode, problems may occur due to the dummy bearer used. Here, consider the case where a single bearer method is used, in which one slot is used as a dummy bearer. As shown in FIG. 11(A), assume that the parent device A at the source and the parent device B at the destination use different slots as dummy bearers. In this case, by searching for slots, if a signal is sent through a slot different from the previous slot, the handset can identify that slot as the dummy bearer of the parent device B at the destination, and the handover is established.

However, as shown in FIG. 11(B), assume that the parent device A at the source and the parent device B at the destination use the same slot as a dummy bearer. In this case, an event occurs in which the child device cannot find the dummy bearer sent by the parent device B at the destination. In other words, if the slots used as dummy bearers by parent devices A and B are the same, it becomes necessary to identify which parent device the signal is from, even if the communication channels are different. For this reason, the dummy bearer from the parent device B at the destination cannot be identified based on the difference in slots alone, and the handover is not established.

As a solution, it is possible to use a double dummy bearer method in which two slots are used as dummy bearers at the same time, as shown in FIG. 11(C). As a result, even if slot S0 is used as a dummy bearer by parent device A and parent device B, slot S4 is only used by parent device B, so the child device can find the signal transmitted in slot S4 from parent device B, and handover is established. However, even with the double dummy bearer method, if parent device A and parent device B use the same slot, the result will be the same as with the single bearer method.

In addition, in the case of the double dummy bearer method, the parent unit always uses two slots as dummy bearers in standby mode, which has the disadvantage of narrowing the range of selectable slots and compressing the available bandwidth. Furthermore, since each parent unit is installed separately and cannot receive dummy bearers from all other parent units, each parent unit cannot know which slots the other parent units are using as dummy bearers.

In view of the above, the object of this invention is to enable control of the slots used as dummy bearers (slots for control signals) by each parent device contained in a telephone control device, and to enable proper handover in standby mode.

In order to solve the above problems, the telephone system of the present invention as set forth in claim 1 comprises:
A telephone system comprising a cordless telephone device including a base unit and a handset, and one or more base units of the cordless telephone device are connected to a telephone control device connected to a wide area network, wherein a predetermined communication channel is divided into frames of a predetermined time unit between the base unit and the handset, each of the frames is further divided into a plurality of time slots, and wireless communication is performed through the time slot selected for each frame,
The parent unit is
a slot table storage means for managing the priority order of each of the plurality of time slots and the time slots selected as control signal slots;
a slot control means for selecting the time slot to be used as a control signal slot in each frame in accordance with the priority order of the slot table storage means when in a standby state, and for transmitting various control signals to the child device;
a slot notification means for notifying said telephone control device of slot notification information including slot identification information of the control signal slot selected by said slot control means and terminal identification information of said own device,
said slot control means, when the slot control information from said telephone control device is information instructing a priority order, is capable of changing the priority order of each of said plurality of time slots in said slot table storage means ;
The telephone control device includes:
a terminal-specific slot table storage means for managing, for each of the master units, the priority order for each of the plurality of time slots and the time slots selected as slots for control signals;
a management information creating means for updating the time slot selected as the control signal slot for the parent device that is the source of the slot notification information in the terminal-specific slot table storage means based on the slot notification information when the slot notification information is received from the parent device, and updating the priority order of each of the multiple time slots of other parent devices;
and a base unit control means for forming information indicating a priority for each of the base units when the priority for each of the plurality of time slots is updated based on the information of the terminal-specific slot table storage means created by the management information creation means, and providing this information to the corresponding base unit as the slot control information.

According to this invention, the telephone control device can grasp the control signal slot used by the base unit of the cordless telephone device accommodated in the telephone control device. Based on the grasped information, the telephone control device can control which slot each base unit uses as a control signal slot. This makes it possible to control the slots used as control signal slots by each base unit accommodated in the telephone control device, and makes it possible to perform handovers in a standby state appropriately.

FIG. 1 is a diagram for explaining an example of the overall configuration of a telephone system according to an embodiment; FIG. 2 is a block diagram showing a configuration example of a main device according to an embodiment. 11 is a diagram for explaining an example of stored data in a terminal-specific slot table provided in a main device of an embodiment. FIG. 2 is a block diagram showing a configuration example of a parent device according to an embodiment; 11 is a diagram for explaining an example of stored data in a slot table provided in a parent device of an embodiment. FIG. 2 is a block diagram showing a configuration example of a slave unit according to an embodiment; FIG. FIG. 4 is a sequence diagram for explaining the operation of the telephone system according to the embodiment. 11 is a flowchart for explaining a process relating to a slot performed in the parent machine of the embodiment. 11 is a flowchart illustrating a slot management process performed by the main device according to the embodiment. FIG. 2 is a diagram for explaining frames and slots of the DECT standard. 11 is a diagram for explaining an example of a method of using a dummy bearer (a slot for control signal). FIG.

Below, an embodiment of the telephone system, cordless telephone base unit, and telephone control device of the present invention will be described with reference to the drawings. In the embodiment described below, the telephone system of the present invention will be described as an example applied to a business phone system configured by connecting multiple cordless telephone devices to a main unit as a telephone control device.

[Telephone system configuration example]
Fig. 1 is a block diagram showing an example of the overall configuration of a telephone system 10 according to this embodiment. In the telephone system 10, a plurality of cordless telephone devices 21, 22, and 23 are connected as extension telephone devices to a main device 1 as an example of a telephone control device. For ease of explanation, this embodiment will be described by taking as an example a case in which three sets of cordless telephone devices 21, 22, and 23 are connected to the main device 1 to configure the telephone system 10 as shown in Fig. 1. However, this is not limited to this, and it is also possible to connect even more cordless telephone devices to the main device 1 to configure a larger-scale telephone system.

Each of the cordless telephone devices 21, 22, 23 consists of a base set BS1, BS2, BS3 as a parent device and a handset HS1, HS2, HS3 as a child device. The base set may also be called a "cell station" or "CS", and the handset may also be called a "personal station" or "PS". In the following, the base sets BS1, BS2, BS3 will be referred to as parent devices BS1, BS2, BS3, and the handsets HS1, HS2, HS3 will be referred to as child devices HS1, HS2, HS3. The parent devices BS1, BS2, BS3 and the child devices HS1, HS2, HS3 are wirelessly connected.

Although it is possible to wirelessly connect multiple handset units to each of the base units BS1, BS2, and BS3, in this example, one handset unit is connected to one base unit. Also, although not shown in the figures, the extension telephone devices connected to the main unit 1 are not limited to the cordless telephone units 21, 22, and 23, and digital key telephone terminals can also be connected , as in a normal business phone system.

In this embodiment, the wireless connections between the base units BS1, BS2, BS3 of the cordless telephone devices 21, 22, 23 and the handset units HS1, HS2, HS3 are made by a TDMA/TDD method using the DECT standard (method) for digital cordless telephones described above. The main device 1 can accommodate one or more telephone lines L1 to Lm (m is an integer of 2 or more). The base units BS1, BS2, BS3 of the cordless telephone devices 21, 22, 23 are connected to the main device 1. In the example of FIG. 1, the base units BS1, BS2, BS3 and the main device 1 are connected by wires, but they may also be connected wirelessly.

The main unit 1 performs call control and line switching control for the multiple cordless telephone devices 21, 22, and 23, as well as other business phone control, and also has the function of supplying a reference synchronization signal SYNC to each of the multiple cordless telephone devices 21, 22, and 23. In this example, the reference synchronization signal SYNC is a signal with a period of 130 milliseconds (ms).

Each of the base units BS1, BS2, and BS3 of the cordless telephone devices 21, 22, and 23 synchronizes with the reference synchronization signal SYNC from the main unit 1 to generate a frame synchronization signal as a synchronization signal with a period of one frame (10 milliseconds (ms)), which is the unit communication period of a DECT standard digital cordless telephone, and performs TDMA/TDD wireless communication using the DECT standard with the handset units HS1, HS2, and HS3 based on the generated frame synchronization signal. Therefore, all of the multiple cordless telephone devices 21, 22, and 23 operate in synchronization with the reference synchronization signal SYNC from the main unit 1.

As shown in FIG. 1, each of the cordless telephone devices 21, 22, and 23 is a telephone terminal that is connected to the main unit 1 to form a business phone system. For this reason, call control signals such as incoming call notifications and outgoing call requests, and other control signals are sent and received between the main unit 1. Note that other control signals include, for example, control signals for controlling the LCDs (Liquid Crystal Displays) and LEDs (Light Emitting Diodes) of the cordless telephone devices 21, 22, and 23 to notify the user of the operating status of other cordless telephone devices connected to the main unit 1.

In some cordless telephone devices, the base unit is equipped with a user interface such as a ringer, LCD, LED, and operation unit. However, there are also cases where the base unit only realizes the function of connecting the main unit and the handset, and the handset is equipped with a user interface such as a ringer, LCD, LED, and operation unit. In this case, various control signals are sent and received between the base unit and the handset. In this embodiment, too, the base units BS1, BS2, and BS3 of the cordless telephone devices 21, 22, and 23 basically do not have a user interface, but realize the function of connecting the main unit 1 and the handset HS1, HS2, and HS3.

Each of the parent units BS1, BS2, and BS3 is installed at a predetermined location in the office. As a result, as shown in FIG. 1, the parent unit BS1 is able to communicate with the child units HS1, etc. in the wireless communication area Ar1, and the parent unit BS2 is able to communicate with the child units HS2, etc. in the wireless communication area Ar2. The parent unit BS3 is able to communicate with the child units HS3, etc. in the wireless communication area Ar3.

In this way, the parent units BS1, BS2, BS3 and the child units HS1, HS2, HS3 form wireless communication areas Ar1, Ar2, Ar3 where wireless communication is possible based on their respective communication functions. The wireless communication areas Ar1, Ar2, Ar3 are set up so that they overlap slightly. This allows the child units HS1, HS2, HS3 to move within the wireless communication areas Ar1, Ar2, Ar3 by switching the parent unit BS1, BS2, BS3 with which they communicate, whether they are in standby or in a call state.

However, as mentioned above, if the control signal slots (dummy bearers) used by the parent units BS1, BS2, and BS3 overlap when in a standby state (idle state), there is a problem that handover may not be possible. Note that the standby state (idle state) refers to a state in which the parent unit and the child units are powered on and can receive and make calls, but no processing is being performed; it is a so-called standby state.

Therefore, when each of the parent devices BS1, BS2, and BS3 is in a standby state, it notifies the main device 1 of slot notification information TJ, which includes slot identification information of the slot currently being used as a dummy bearer and its own terminal identification information, at a predetermined timing. Here, the predetermined timing means regular timing, or timing when a dummy bearer is newly acquired, or timing when the dummy bearer is changed. Of course, the slot notification information TJ may be transmitted periodically and also when a dummy bearer is acquired or changed.

This allows the main unit 1 to know which slots are used as dummy bearers by all the parent units BS1, BS2, and BS3 connected to the main unit 1. The main unit 1 manages the slots used by the parent units BS1, BS2, and BS3 as dummy bearers, and can form slot control information CTL for controlling the slots used as dummy bearers as necessary and provide it to the parent units BS1, BS2, and BS3. The slot control information CTL is for controlling the priority of obtaining slots used as dummy bearers, controlling changes to slots used as dummy bearers, and controlling the number of slots used as dummy bearers. This prevents overlapping of slots used as dummy bearers in the parent units BS1, BS2, and BS3 in the standby state, and allows handover in the standby state to be performed appropriately.

The following describes an example of the configuration of the main device 1 and the cordless telephone devices 21, 22, and 23 that make up the telephone system of this embodiment. Note that the base units BS1, BS2, and BS3 of the cordless telephone devices 21, 22, and 23 are configured in the same way. Also, the handset units HS1, HS2, and HS3 of the cordless telephone devices 21, 22, and 23 are configured in the same way. For this reason, the configuration of the cordless telephone devices 21, 22, and 23 will be described using the cordless telephone device 21 as an example.

[Configuration example of main device 1]
Fig. 2 is a block diagram showing an example of the configuration of the main unit 1. As shown in Fig. 2, the main unit 1 is configured to include a line interface 11 to which telephone lines L1 to Lm are connected, a control circuit 12 equipped with a computer for controlling the entire main unit 1, a line LSI (Large Scale Integrated Circuit) unit 13, a terminal-specific slot table 14, and a reference oscillator 15.

Under the control of the control circuit 12, the line interface 11 supplies voice signals (received voice signals) from the lines L1 to Lm to the line LSI unit 13, and supplies control signals such as call control signals from the lines to the control circuit 12. Also, under the control of the control circuit 12, the line interface 11 transmits voice signals (outgoing voice signals) from the line LSI unit 13 to the other party via the lines L1 to Lm, and also transmits control signals such as call control signals from the control circuit 12 to the other party via the lines L1 to Lm.

The line LSI unit 13 is equipped with n extension processing circuits 131, 132, ..., 13n corresponding to n extension telephone devices, and a timing signal generating unit 130. The subscript n basically means an integer of 1 or more. However, in FIG. 2, the extension processing circuits 131 and 132 already exist, so the letter n in FIG. 2 means an integer of 3 or more.

The timing signal generating unit 130 generates a transmission clock signal CK and a multiplexing/division timing signal TM from a reference clock signal from a high-precision reference oscillator 15 using a quartz crystal resonator, and supplies these to n extension processing circuits 131 to 13n. The n extension processing circuits 131 to 13n have the exact same configuration, and each comprises a voice signal processing unit 31, a control signal processing unit 32, a synchronization signal processing unit 33, and a multiplexing/division processing unit 34.

The audio signal processing unit 31 is connected to the line interface 11 and to the multiplexing/division processing unit 34, and is a processing circuit for the received audio signal from the line interface 11 and the transmitted audio signal from the multiplexing/division processing unit 34. The audio signal processing unit 31 is supplied with a transmission clock signal CK from the timing signal generating unit 130.

The control signal processing unit 32 is connected to the control signal input/output terminal of the control circuit 12 and is also connected to the multiplexing/division processing unit 34, and is a processing circuit for control signals such as call control signals when making and receiving calls, and when ending a call. In other words, the control signal processing unit 32 is a processing circuit for both control signals from the main unit 1 to the cordless telephone device, and control signals from the cordless telephone device to the main unit 1. The control signal processing unit 32 is also supplied with the transmission clock signal CK from the timing signal generating unit 130.

The synchronization signal processing unit 33 is connected to the synchronization signal output terminal of the control circuit 12 and is also connected to the multiplexing/division processing unit 34, and is a processing circuit for the reference synchronization signal SYNC having a predetermined synchronization signal pattern from the control circuit 12. Similarly, the transmission clock signal CK from the timing signal generating unit 130 is also supplied to this synchronization signal processing unit 33.

The multiplexing/division processing unit 34 is connected to the audio signal processing unit 31, the control signal processing unit 32, and the synchronization signal processing unit 33, and is also connected to each of the base units BS1 to BSn of the cordless telephone devices 21 to 2n. The multiplexing/division processing unit 34 multiplexes (time division multiplexes) the audio signal from the audio signal processing unit 31, the control signal from the control signal processing unit 32, and the reference synchronization signal SYNC from the synchronization signal processing unit 33 based on the timing signal TM from the timing signal generating unit 130 to generate a multiplexed signal, and supplies the generated multiplexed signal to each of the base units BS1 to BSn. The multiplexing/division processing unit 34 also divides the multiplexed signal from each of the base units BS1 to BSn into an audio signal and a control signal based on the timing signal TM from the timing signal generating unit 130, and supplies the audio signal to the audio signal processing unit 31 and the control signal to the control signal processing unit 32.

The terminal slot table 14 is formed on a recording medium, such as a hard disk drive (HDD) or solid state drive (SSD), in a device section that includes a recording medium and its driver. The terminal slot table 14 is created by the management information creation section 121 of the control circuit 12 based on slot notification information TJ provided by each of the parent units BS1, BS2, and BS3. The created terminal slot table 14 is referenced and used by the parent unit control section 122 of the control circuit 12. The parent unit control section 122 creates slot control information CTL to be supplied to the parent unit connected to itself based on the stored data in the terminal slot table 14, and provides this to the parent unit to control the selection of slots in the parent unit.

3 is a diagram for explaining an example of data stored in the terminal slot table 14. As shown in FIG. 3, the terminal slot table 14 in this embodiment has a storage field for a "parent unit ID (described as "parent unit" in FIG. 3)" and a storage field for an "installation location". The "parent unit ID" is information for identifying a parent unit under the main device 1, and is, for example, an extension number, an IP address, a URL (Uniform Resource Locator), or a MAC (Media Access Control) address. In FIG. 3, in order to clearly distinguish each parent unit, "BS1", "BS2", and "BS3" are described as "parent unit IDs". The "installation location" is information for identifying the installation location of each parent unit. In this embodiment, it is shown that the parent unit BS1 is installed at position A on the first floor of the office, the parent unit BS2 is installed at position B on the first floor of the office, and the parent unit BS3 is located at position C on the first floor of the office.

In this embodiment, position A on the first floor of the office corresponds to the installation position of base unit BS1 in FIG. 1, position B on the first floor of the office corresponds to the installation position of base unit B2 in FIG. 1, and position C on the first floor of the office corresponds to the installation position of base unit B3 in FIG. 1. Therefore, it can be understood that base unit BS1 is installed near the center of wireless communication area Ar1 on the first floor, base unit BS2 is installed near the center of wireless communication area Ar2 on the first floor, and base unit BS3 is installed near the center of wireless communication area Ar3 on the first floor.

In reality, the wireless communication area Ar1 corresponds to the area where the general affairs department desks are located, the wireless communication area Ar2 corresponds to the area where the accounting department desks are located, and the wireless communication area Ar3 corresponds to the area where the sales department desks are located. In this way, based on the "installation location" in the terminal-specific slot table 14, it is possible to know where in the office each base unit is installed. In addition, the size of the wireless communication areas Ar1, Ar2, and Ar3 can be determined with each base unit BS1, BS2, and BS3 at the center, so it is also possible to know whether there are any overlapping areas between these areas.

In the case of parent units BS1, BS2, and BS3 installed on the same floor of an office, as explained with reference to FIG. 1, the wireless communication areas (radio wave areas) formed by the parent unit and child unit are designed to overlap slightly to allow smooth handover. Therefore, based on the "installation position" in the terminal-specific slot table 14, it can be determined that the wireless communication areas formed by parent units installed on the same floor overlap with the wireless communication areas formed by nearby parent units (areas overlap).

For this reason, it is also possible to have information in the terminal slot table, which is not shown in FIG. 3, indicating which parent device's wireless communication area the wireless communication area formed by each parent device overlaps with. The "installation location" and information indicating which parent device's wireless communication area the wireless communication area formed by each parent device overlaps with can be set in the terminal slot table 14 or in the parent device's slot table, which will be described later, by the user, who decides the placement location of the parent device.

In addition, the terminal-specific slot table 14 has storage columns for "priority" and "used slot (shown as "used SL" in FIG. 3)" for each of the 12 downlink slots S0 to S11, as shown in the "slot" column in FIG. 3. The "priority" storage column stores the priority when each slot is acquired as a dummy bearer. In the initial state, the slots with smaller numbers in the slot identifiers S0 to S11 have higher priority. The priority for each slot is also managed in each parent device BS1, BS2, and BS3 in synchronization with the state of the terminal-specific slot table 14 of the main device 1. In the "used slot" storage column, a flag is set in the column corresponding to the slot currently selected as a dummy bearer in each parent device, as shown by a circle, so that this can be understood.

Now, consider a case in which, in the telephone system of this embodiment described with reference to Figure 1, slots to be used as dummy bearers are acquired in the order of base unit B1 → base unit BS2 → base unit BS3, and the acquired slots are notified to main unit 1 as slot notification information TJ. In this case, as described above, the priority of slots acquired as dummy bearers in each of base units BS1, BS2, and BS3 is such that the slots with smaller numerical parts of the slot identifiers S0 to S11 have higher priority. Therefore, slot S0 has the highest priority, and slot S11 has the lowest priority.

First, assume that parent device BS1 acquires slot S0, which has the highest priority, as a dummy bearer and notifies main device 1 of this as slot notification information TJ. The slot notification information TJ from parent device BS1 is supplied to control circuit 12 via multiplexing/division processing unit 34 and control signal processing unit 32. Based on the slot notification information TJ, management information creation unit 121 updates the information that slot S0 has been acquired as a dummy bearer and has become a used slot, as shown in the "Used Slot" column of parent device BS1 in Figure 3 (A). Therefore, parent devices BS2 and BS3 should not acquire slot S0 as a dummy bearer.

In this case, the base unit control unit 122 updates the priority of the base units BS2 and BS3 in the terminal slot table 14 based on the information stored in the base unit BS1 in the terminal slot table 14 so that slot S0 becomes the lowest. Furthermore, the base unit control unit 122 forms information indicating the priority with slot S0 at the lowest based on the data stored in the terminal slot table 14 as slot control information CTL, and provides this to the base units BS2 and BS3. The base units BS2 and BS3 update the priority regarding the acquisition of slots managed by them based on the slot control information CTL from the main unit 1.

After this, assume that the parent device BS2 acquires slot S1, which currently has the highest priority, as a dummy bearer and notifies the main device 1 of this as slot notification information TJ. Based on the slot notification information TJ, the management information creation unit 121 updates the information that slot S1 has been acquired as a dummy bearer and has become a used slot, as shown in the "Used Slot" column of parent device BS2 in FIG. 3(A). In this case, it is better for parent device BS3 not to acquire slots S0 and S1 as dummy bearers.

In this case, the parent control unit 122 updates the priority of the parent unit BS3 in the terminal slot table 14 based on the stored information of the parent unit BS2 in the terminal slot table 14 so that slot S1 becomes the lowest. In this example, as described above, slot S0 has been acquired by the parent unit BS1, so slot S0 is updated to become the next lowest. Based on the stored data in the terminal slot table 14, the parent control unit 122 forms information indicating the priority with slot S1 becoming the lowest and slot S0 becoming the next lowest as slot control information CTL, and provides this to the parent unit BS3. The parent unit BS3 updates the priority regarding the acquisition of slots managed by itself based on the slot control information CTL from the main unit 1.

After this, assume that the parent device BS3 acquires slot S2, which currently has the highest priority, as a dummy bearer and notifies the main device 1 of this as slot notification information TJ. Based on the slot notification information TJ, the management information creation unit 121 updates the information to indicate that slot S2 has been acquired as a dummy bearer and has become a used slot, as shown in the "Used Slot" column of parent device BS3 in FIG. 3(A). In this way, by controlling the priority of slot acquisition, parent devices BS1, BS2, and BS3 can acquire slots to be used as dummy bearers without overlapping.

However, if the state shown in FIG. 3(A) remains unchanged, the priority of slot acquisition for the parent device BS1 remains high, even though it should be lower because slot S1 is acquired by parent device BS2 and slot S2 is acquired by parent device BS3. Similarly, the priority of slot acquisition for the parent device BS2 remains high, even though it should be lower because slot S2 is acquired by parent device BS3. Therefore, the parent device control unit 122 changes (updates) the priority of slot acquisition for the parent devices BS1 and BS2, as shown in FIG. 3(B), based on the information in the terminal slot table 14 shown in FIG. 3(A). After this, the parent device control unit 122 forms slot control information CTL that indicates the priority to be provided to each of the parent devices BS1 and BS2, based on the terminal slot table in the state shown in FIG. 3(B), and provides it to the parent devices BS1 and BS2.

As a result, the parent devices BS1, BS2, and BS3 can acquire a traffic bearer by answering an incoming call or making an outgoing call, and then when acquiring a dummy bearer again after releasing the dummy bearer, they can acquire an appropriate slot according to an appropriate priority order. Note that the above description is given using an example in which the parent devices BS1, BS2, and BS3 acquire slots to be used as dummy bearers in turn. However, in reality, it is considered that there may be cases in which a parent device acquires a slot that has already been acquired by another parent device and notifies this as slot notification information TJ.

In this case, the parent device control unit 122 instructs one of the parent devices with overlapping slots acquired as dummy bearers to change the slots acquired as dummy bearers according to the data stored in the terminal-specific slot table 14. The instruction is provided to the parent device as slot control information CTL. The parent device control unit 122 then updates the "used slots" in the terminal-specific slot table, and accordingly updates the "priority" according to the latest acquisition status of slots as dummy bearers. The parent device control unit 122 then functions to form slot control information CTL that notifies the parent device of the priority of slot acquisition, and provides this to each parent device, so that the priority of slot acquisition managed by each parent device can also be appropriately updated.

In this way, the main unit 1 prepares the terminal-specific slot table 14 based on the slot notification information TJ from each parent unit BS1, BS2, BS3, and can grasp the status of slot acquisition as a dummy bearer in each parent unit BS1, BS2, BS3. Furthermore, the main unit 1 can appropriately update the priority of slot acquisition for each parent unit BS1, BS2, BS3 based on the data stored in the terminal-specific slot table 14, and provide this according to each parent unit BS1, BS2, BS3. In addition, the main unit 1 can also control each parent unit to change the slot to be acquired as a dummy bearer if the slot acquired as a dummy bearer overlaps with another parent unit.

Furthermore, the main device 1 can use the functions of the parent device control unit 122 to control the number of slots acquired as dummy bearers for each parent device, depending on the acquisition status of slots as dummy bearers for the parent devices connected to the main device itself. In other words, it can control to select either the single dummy bearer method or the double dummy bearer method. Of course, it can also control to acquire more than two slots as dummy bearers. For example, it can also control each parent device to use the double dummy bearer method or the triple dummy bearer method, depending on the number of parent devices connected to the main device 1 and the status of slots actually acquired as dummy bearers.

Although not shown in FIG. 2, an address management unit is also connected to the main unit 1. The address management unit stores and manages the correspondence between terminal identification information, such as the extension numbers of the cordless telephone devices 21, 22, and 23 connected to the main unit 1, and each of the extension processing circuits 131 to 13n. Based on the information from this address management unit, the operating status of the cordless telephone devices connected to the main unit 1 can be properly understood, and each of the cordless telephone devices connected to the main unit 1 can be properly controlled.

[Example of configuration of cordless telephone devices 21, 22, and 23]
Next, an example of the configuration of the cordless telephone devices 21, 22, and 23 of this embodiment, which are composed of a base unit and a handset, will be described. As described above, the cordless telephone device 21 composed of the base unit BS1 and the handset HS1 will be described as an example.

<Example of parent unit configuration>
Fig. 4 is a block diagram showing an example of the configuration of the master BS 1. As shown in Fig. 4, the master BS 1 is configured to include a control circuit 41 for controlling the entire master BS 1, a line LSI unit 42, a synchronization signal generating circuit 43, a wireless communication circuit 44, and oscillators 45 and 46.

The control circuit 41 is configured with a computer mounted thereon. The control circuit 41 has a function of controlling the call control and the like in the parent unit BS1. The control circuit 41 also has a slot table 411, a slot control unit 412, and a slot notification unit 413. Each of these units cooperates with the main device 1 to realize a function of appropriately acquiring a slot to be used as a dummy bearer in a standby state without overlapping with other parent units. The details of each unit of the control circuit 41 will be described later.

The line LSI unit 42 is a circuit for exchanging audio signals, control signals, and synchronization signals with the main unit 1. The line LSI unit 42 is made up of a division/multiplexing processing unit 421, a control signal processing unit 422, an audio signal processing unit 423, a synchronization signal detection unit 424, and a PLL (Phase Locked Loop) unit 425. The PLL unit 425 is supplied with an oscillation signal of a reference frequency from the oscillator 45, and is also supplied with a multiplexed signal from the main unit 1. In this example, the frequency of the oscillation signal of the oscillator 45 is set to, for example, 2048 MHz (0.488 nanoseconds (ns)).

The PLL unit 425 extracts the clock signal CK component from the timing signal generating unit of the main unit 1 from the multiplexed signal from the main unit 1 by so-called self-clocking. The PLL unit 425 compares the phase of the extracted clock signal CK component with the oscillation signal from the oscillator 45, and based on the comparison result, generates a system clock signal SCK for the parent unit BS1 that is synchronized with the clock signal CK component from the oscillation signal of the oscillator 45. The PLL unit 425 supplies the generated system clock signal SCK to each of the division/multiplexing processing unit 421, the control signal processing unit 422, the audio signal processing unit 423, and the synchronization signal detection unit 424 as a clock signal for signal processing, and also supplies it to the synchronization signal generating circuit 43.

The division/multiplexing processing unit 421 is connected to the main device 1, and is also connected to the control signal processing unit 422, the audio signal processing unit 423, and the synchronization signal detection unit 424. The division/multiplexing processing unit 421 divides (separates) the multiplexed signal from the main device 1 into a control signal, an audio signal, and a reference synchronization signal SYNC. The control signal, the audio signal, and the reference synchronization signal SYNC divided (separated) by the division/multiplexing processing unit 421 are supplied to the control signal processing unit 422, the audio signal to the audio signal processing unit 423, and the reference synchronization signal SYNC to the synchronization signal detection unit 424, respectively.

The division/multiplexing processing unit 421 also multiplexes the control signal from the control signal processing unit 422 and the audio signal from the audio signal processing unit 423 to generate a multiplexed signal, and supplies the generated multiplexed signal to the main unit 1. The control signal processing unit 422 is connected to the control signal input/output terminal of the control circuit 41 and is also connected to the division/multiplexing processing unit 421. The control signal processing unit 422 is a processing circuit for control signals (both control signals from the main unit 1 to the cordless telephone device 21 and control signals from the cordless telephone device 21 to the main unit 1) such as call control signals when making and receiving an outgoing call, and when ending a call. The control signal processing unit 422 also realizes the function of providing slot notification information TJ from the control circuit 41 to the main unit 1, and providing slot control information CTL from the main unit 1 to the control circuit 41.

The audio signal processing unit 423 is connected to the wireless communication circuit 44 and the division/multiplexing processing unit 421, and is a processing circuit for the outgoing voice signal received from the handset HS1 from the wireless communication circuit 44 and the received voice signal from the division/multiplexing processing unit 421. The synchronization signal detection unit 424 receives the reference synchronization signal SYNC from the division/multiplexing processing unit 421 and detects a predetermined synchronization signal pattern contained in the reference synchronization signal SYNC. As a result, the synchronization signal detection unit 424 generates a reference synchronization pulse PS that is synchronized with the reference synchronization signal SYNC and has the same period (130 ms) as the reference synchronization signal SYNC as a signal at the time of detection. The synchronization signal detection unit 424 supplies the generated reference synchronization pulse PS to the synchronization signal generation circuit 43.

The synchronization signal generating circuit 43 consists of a counter 431 and a synchronization signal generating unit 432. The counter 431 receives a reference synchronization pulse PS with a period of 130 ms from the synchronization signal detecting unit 424 of the line LSI unit 42 at a preset terminal PRE, and receives a system clock signal SCK from the PLL unit 425 as a count input. The output count value CNT of the counter 431 is supplied to the synchronization signal generating unit 432. The synchronization signal generating unit 432 generates a synchronization signal FL with a frame period (10 ms) of the DECT standard from the output count value CNT of the counter 431. The synchronization signal generating circuit 43 supplies the frame synchronization signal FL generated by the synchronization signal generating unit 432 to the wireless communication circuit 44.

The wireless communication circuit 44 is configured with a control unit 441, a TDMA modulation/demodulation unit 442, and a wireless communication unit (indicated as "RF" in FIG. 4) 443. The wireless communication unit 443 is a circuit unit for performing wireless communication with the handset HS1. The control unit 441 is connected to the TDMA modulation/demodulation unit 442 and the wireless communication unit 443, and is also connected to the control circuit 41. The control unit 441 controls the overall operation of this wireless communication circuit 44, and supplies a control signal based on a control signal obtained from the control circuit 41 to the TDMA modulation/demodulation unit 442. The control unit 441 also has a function of supplying information obtained from the TDMA modulation/demodulation unit 442 to the control circuit 41.

The TDMA modulation/demodulation unit 442 is connected to the control unit 441 and the audio signal processing unit 423 of the line LSI unit 42, and is also connected to the wireless communication unit 443, and performs modulation to transmit the control signal from the control unit 441 and the audio signal from the audio signal processing unit 423 to the handset HS1. The signal modulated by this TDMA modulation/demodulation unit 442 is transmitted to the handset HS1 via the wireless communication unit 443. The TDMA modulation/demodulation unit 442 also demodulates the audio signal and control signal from the signal received from the handset HS1 and received by the wireless communication unit 443, supplies the demodulated audio signal to the audio signal processing unit 423, and supplies the demodulated control signal to the control unit 441.

The TDMA modulation/demodulation unit 442 includes a PLL unit 4421 for clock generation. The PLL unit 4421 is supplied with an oscillation signal from the oscillator 46 and a frame synchronization signal FL from the synchronization signal generation circuit 43. The PLL unit 4421 compares the phase of the frame synchronization signal FL from the synchronization signal generation circuit 43 with the oscillation signal from the oscillator 46, and generates a timing signal and a clock signal synchronized with the frame synchronization signal FL from the oscillation signal of the oscillator 46 based on the comparison result. The TDMA modulation/demodulation unit 442 uses the timing signal and the clock signal synchronized with the frame synchronization signal FL to generate a transmission signal to the child unit HS1 in a period corresponding to the slot in the downlink that can be allocated and used, and processes the reception signal from the child unit HS1 using the slot in the uplink.

When the parent unit BS1 is connected to the main device 1 and is in a standby state, it starts a synchronization process for communication with the child unit HS1, and always transmits a synchronization signal and control information to the child unit HS1 through a dummy bearer, maintaining a state in which communication is possible (so-called an idle state). That is, when in a standby state, the TDMA modulation/demodulation unit 442 transmits a synchronization signal and control information to the child unit HS1 through the specified slot (dummy bearer) via the wireless communication unit 443 in response to control from the control circuit 41 through the control unit 441.

When notifying handset HS1 of an incoming call or when making an outgoing call from the handset, as described above, the dummy bearer is merged with the traffic bearer, and communication is performed through the traffic bearer acquired on the downlink and uplink. This process of merging the dummy bearer with the traffic bearer is performed mainly by the TDMA modulation/demodulation unit 442 under the control of the control unit 441 in response to a request from the handset to acquire a traffic bearer.

The process of acquiring the dummy bearer is performed in the control circuit 41. The slot table 411 provided in the control circuit 41 is formed in a memory provided in the control circuit 41. The slot table 411 manages the priority order when acquiring each downlink slot as a dummy bearer and the slot acquired as a dummy bearer. FIG. 5 is a diagram for explaining an example of stored data in the slot table 411. As shown in FIG. 5, the slot table 411 has a storage column for "installation location". The "installation location" is information that specifies the installation location of the parent unit BS1, similar to the "installation location" in the terminal-specific slot table 14 of the main device 1 described using FIG. 3, and in this embodiment, it is stored that the parent unit BS1 is installed at position A on the first floor of the office.

In addition, as shown in the "Slot" column in FIG. 5, the slot table 411 has storage columns for "priority" and "used slot (shown as "used SL" in FIG. 3)" for each of the 12 downlink slots S0 to S11. The "priority" storage column stores the priority used when each slot is acquired as a dummy bearer. In the initial state, the slots with smaller numbers in the slot identifiers S0 to S11 have higher priority. As described above, this "priority" information is synchronized with and made consistent with the "priority" of the parent device BS1 in the terminal-specific slot table 14 of the main device 1.

In the "used slot" storage field, a flag is set in the field corresponding to the slot currently selected as a dummy bearer in the parent device BS1, as shown by a circle, so that this can be grasped. In this way, the slot table 411 of the control circuit 41 of the parent device BS1 is configured to manage the same information as the information grasped about the parent device BS1 in the terminal-specific slot table 14 of the main device 1 described above. Based on the information in this slot table 411, the slot control unit 412 realizes the function of acquiring a slot as a dummy bearer, changing the slot acquired as a dummy bearer, and updating the information in the slot table 411. In addition, the slot control unit 412 also performs processing to change the priority order when each slot is acquired as a dummy bearer and change the slot acquired as a dummy bearer based on the slot control information CTL provided from the main device 1, as described above.

The slot notification unit 413 realizes a function of forming slot notification information TJ based on the information in the slot table 411 at each predetermined timing or each time a dummy bearer is acquired , and transmitting this to the main unit 1. The slot notification information TJ has at least slot identification information for identifying the slot acquired as a dummy bearer and identification information (terminal identification information) of the parent unit BS1. The slot notification information TJ may be transmitted to the main unit 1 both at each predetermined timing and each time a dummy bearer is acquired . In addition, the priority of each slot at that time can be notified to the main unit 1 as the slot notification information TJ.

Now, consider the processing of the control circuit 41 when, as described above with reference to FIG. 3, slots to be used as dummy bearers are acquired in the order of parent unit B1 → parent unit BS2 → parent unit BS3, and the acquired slots are notified to the main device 1 as slot notification information TJ. First, as shown in FIG. 5 (A), the slot control unit 412 of the control circuit 41 of the parent unit BS1 acquires (specifies) the slot S0 with the highest priority as the slot to be used as a dummy bearer according to the priority order in the slot table 411. As a result, when in a standby state, the parent unit BS1 transmits synchronization signals and various control information to child units within the wireless communication area Ar1 formed by the parent unit BS1 through the slot S0 as a dummy bearer.

In this case, the slot notification unit 413 forms slot notification information TJ including the slot identification information of the slot S0 acquired as a dummy bearer and the terminal identification information of the parent device BS1, and provides it to the main device 1 through the line LSI 42. In the main device 1 that receives the slot notification information TJ, the management information creation unit 121 of the control circuit 12 updates the column of the used slot of the parent device BS1 in the terminal-specific slot table 14. This allows the main device 1 to manage that the slot S0 has been acquired as a dummy bearer by the parent device BS1.

In this case, the base unit control unit 122 of the control circuit 12 of the main device 1 functions to form a priority order for the base units BS2 and BS3 that lowers the priority order of slot S0, and provides this to the base units BS2 and BS3 as slot control information CTL. This updates the priority order of the slot table 411 of the base units BS2 and BS3, which are configured in the same way as the base unit BS1, making it difficult for the base units BS2 and BS3 to acquire slot S0 as a dummy bearer.

After this, in the parent device BS2, a slot to be a dummy bearer is acquired according to the updated priority of the slot table 411. In this case, as described above, since slot S0 has a low priority, slot S1, which has a high priority, is acquired (identified) as the dummy bearer, and slot notification information TJ notifying this is formed and provided to the main unit 1. In this case, in the main unit 1, the management information creation unit 121 of the control circuit 12 functions and updates the column of the slot used by parent device BS2 in the terminal-specific slot table 14. As a result, the main unit 1 can know that slot S1 has been acquired as a dummy bearer by parent device BS2.

Therefore, in the main device 1, the base unit control unit 122 of the control circuit 12 functions to form a priority order for the base units BS1 and BS3 that lowers the priority of slot S1, and provides this to the base units BS2 and BS3 as slot control information CTL. As a result, in the base units BS1 and BS3, the slot control unit 412 of the control circuit 41 functions to update the priority order in the slot table 411. In this case, in the base unit BS1, as shown in FIG. 5(B), the priority order of slot S1 acquired by the base unit BS2 is set to the lowest (12th place) in this example. This makes it difficult for the base unit BS1 to acquire slot S1 as a dummy bearer. The same processing is also performed in the base unit BS3.

At this point, slot S0 has been acquired by parent unit BS1, and slot S1 has been acquired by parent unit BS2. Therefore, in the slot table 411 of parent unit BS3, slot S0 has a lower priority, 12th, and slot S1 has a lower priority, 11th, making them more difficult to acquire. In this case, in parent unit BS3, slot S2 is acquired (identified) as a dummy bearer according to the updated priority in slot table 411, and slot notification information TJ notifying this is formed and provided to main unit 1.

In the main unit 1, the management information creation unit 121 of the control circuit 12 functions to update the column of the slot used by the parent unit BS3 in the terminal-specific slot table 14. This allows the main unit 1 to understand that slot S2 has been acquired as a dummy bearer by the parent unit BS3. Then, in the main unit 1, the parent unit control unit 122 of the control circuit 12 functions to form a priority order for the parent units BS1 and BS2 that lowers the priority order of slot S2, and provides this to the parent units BS1 and BS2 as slot control information CTL.

As a result, in parent units BS1 and BS2, the slot control unit 412 of the control circuit 41 functions to update the priority of the slot table 411. In this case, in parent unit BS1, as shown in FIG. 5(C), the priority of slot S2 acquired in parent unit BS3 is set to the lowest (11th place) in this example. This makes it difficult for parent unit BS1 to acquire slot S2 as a dummy bearer after slot S1. The same processing is performed in parent unit BS2.

Note that, since the case where slots to be used as dummy bearers are acquired in the order of parent unit B1 → parent unit BS2 → parent unit BS3 has been described here, slot acquisition control is possible by controlling the priority of the slots acquired as dummy bearers. However, if another parent unit acquires as a dummy bearer the same slot as a slot that has already been acquired as a dummy bearer, the parent unit control unit 122 of the main device 1 controls to change the slot acquired as a dummy bearer of one of the parent units.

In this way, the parent device BS1 cooperates with the main device 1 through the functions of the slot table 411, slot control unit 412, and slot notification unit 413 provided in the control circuit 41 to prevent the parent device BS1 from using the same slot as another parent device as a dummy bearer.

<Example of child device configuration>
Fig. 6 is a block diagram showing an example of the configuration of the slave HS1. As shown in Fig. 6, the slave HS1 is configured to include a wireless communication circuit 51, a control circuit 52, a codec circuit 53, an oscillator 54, a microphone 55, and a speaker 56. The microphone 55 constitutes a transmitter, and the speaker 56 constitutes a receiver. The wireless communication circuit 51 is configured to include a control unit 511, a TDMA modulation/demodulation unit 512, and a wireless communication unit (indicated as "RF" in Fig. 7) 513. The wireless communication unit 513 is a circuit unit for performing wireless communication with the master BS1.

The control unit 511 is connected to the TDMA modulation/demodulation unit 512 and the wireless communication unit 513, and is also connected to the control circuit 52. The control unit 511 controls the overall operation of the wireless communication circuit 51, and supplies a control signal to the TDMA modulation/demodulation unit 512 based on a control signal obtained from the control circuit 52.

The TDMA modulation/demodulation unit 512 is connected to the control unit 511 and the wireless communication unit 513, and is also connected to the codec circuit 53, and performs modulation to transmit the control signal from the control unit 511 and the audio signal from the codec circuit 53 to the parent unit BS1. The signal modulated by the TDMA modulation/demodulation unit 512 is transmitted to the parent unit BS1 via the wireless communication unit 513. The TDMA modulation/demodulation unit 512 also demodulates the audio signal and control signal from the signal received from the parent unit BS1 by the wireless communication unit 513, supplies the demodulated audio signal to the codec circuit 53, and supplies the demodulated control signal to the control unit 511.

The TDMA modulation/demodulation unit 512 includes a PLL unit 5121 for clock generation. The PLL unit 5121 is supplied with an oscillation signal from the oscillator 54 and a demodulated signal of the received signal from the wireless communication unit 513, and generates a clock signal synchronized with the clock component of the demodulated signal of the received signal from the oscillation signal from the oscillator 54. The clock signal from the PLL unit 5121 is used as a processing clock signal in the TDMA modulation/demodulation unit 512.

The codec circuit 53 decodes the voice signal demodulated by the TDMA modulation/demodulation unit 512, converts it to an analog voice signal, and supplies the analog voice signal to the speaker 56 to emit it as the received voice. The codec circuit 53 also encodes the analog voice signal picked up by the microphone 55 and supplies it to the TDMA modulation/demodulation unit 512. When a call is made from the handset HS1, the control circuit 52 transmits a call control signal at the time of the call to the base unit BS1 via the wireless communication circuit 51, and when a call control signal at the time of an incoming call is received from the base unit BS1, it performs processing such as emitting an incoming tone from the speaker 56.

The control unit 511 of the wireless communication circuit 51 controls the TDMA modulation/demodulation unit 512 in response to a control signal from the parent unit BS1 corresponding to the device itself, searches for and identifies slots to be used for communication in the downlink and uplink, and performs reception/transmission processing. For example, when a mass incoming call occurs and an incoming call notification from the main unit 1 is notified to the handset HS1 via the parent unit BS1, the handset HS1 searches for an available slot and acquires an available slot to use for the call. The handset HS1 then cooperates with the parent unit BS1 to use the acquired available slot as a traffic bearer to make the call.

As described above, during standby, the handset HS1 is able to receive synchronization and control signals from the parent unit through one predetermined slot (dummy bearer) in the downlink. When an incoming or outgoing call occurs, as described above, the dummy bearer is merged into the traffic bearer, and the slots to be used for communication are identified in the downlink and uplink to carry out the call.

The above explanation is about the base unit BS1 and handset HS1 of the cordless telephone device 21, but as mentioned above, the base units BS2 to BSn and handset units HS2 to HSn of the other cordless telephone devices 22 to 2n also have the same configuration.

[Basic operation of the telephone system]
Fig. 7 is a sequence diagram for explaining the basic operation of the telephone system 10 shown in Fig. 1. Here, for simplicity of explanation, it is assumed that the state of the slot table 411 of the parent devices BS1, BS2, and BS3 is such that the priority decreases from slot S0 to slot S11, with slot S0 having the first priority and slot S11 having the 12th priority. It is also assumed that the state of this slot table 411 is also managed in the terminal-specific slot table 14 of the main unit 1.

First, assume that the slot control unit 412 of the parent device BS1 acquires the highest priority slot S0 as a dummy bearer according to the state of its own slot table 411 (step S31). In this case, the slot notification unit 413 of the parent device BS1 functions to notify the main unit 1 that the parent device BS1 has acquired slot S0 (step S32). In the main unit 1 that has received the notification, the management information creation unit 121 functions to store (update) the notified information in the parent device BS1 column of the terminal-specific slot table 14 (step S33). Specifically, the process of step S33 is a process of setting a flag indicating that slot S0 is in use in the column corresponding to slot S0 in the used slot column of the parent device BS1.

Then, the base unit control unit 122 of the main device 1 checks the terminal-specific slot table 14 and forms a priority order for acquiring dummy bearers with the priority order of slot S0 lowered (step S34). The base unit control unit 122 provides the priority order formed in step S34 to the base units BS2 and BS3 as slot control information CTL instructing a change in priority order (step S35). In response to this, the slot control unit 412 in the base units BS2 and BS3 functions and changes the priority order in the slot table 411 (steps S36, S37).

In this case, in response to instructions from the main device 1, the parent devices BS2 and BS3 change the priority of the slot table 411 so that the priority of slot S0 is the lowest, slot S1 is the highest, and the priority of slots decreases in the order of S2 → S3 → S4, etc. Also, in step S34, the parent device control unit 122 updates the priority of the terminal-specific slot table 14 so that it matches the priority of the slot table 411 of each parent device.

After that, in the parent device BS2, the slot control unit 412 functions to acquire the slot S1 with the highest priority as a dummy bearer (step S38), and the slot notification unit 413 functions to notify the main device 1 that slot S1 has been acquired (step S39). Immediately after this, in the parent device BS3, the slot control unit 412 functions to acquire the slot S1 with the highest priority as a dummy bearer (step S40), and the slot notification unit 413 functions to notify the main device 1 that slot S1 has been acquired (step S41). In other words, before the acquisition of slot S1 by parent device BS2 is reflected in the terminal-specific slot table 14, parent device BS3 also acquires a slot to be used as a dummy bearer.

In this case, the parent device BS3 has also acquired a slot to be used as a dummy bearer before the priority of the slot table of the parent device BS3 is changed, so the parent device BS3 has also acquired slot S1. This state is stored in the terminal-specific slot table 14 by the management information creation unit 121 of the main device 1 (step S42), and it is understood that slot S1 has been acquired as a dummy bearer in duplicate in the parent devices BS2 and BS3.

Next, the base unit control unit 122 of the main unit 1 checks the stored data in the terminal-specific slot table 14 (step S43), and finds that the slots acquired as dummy bearers by base units BS2 and BS3 overlap. In this case, based on the confirmed contents, the base unit control unit 122 of the main unit 1 forms a slot change instruction as slot control information CTL to instruct base unit BS3 to release slot S1 and acquire slot S2, and provides this to base unit BS3 (step S44). As a result, slot S1 is released in base unit BS3, and slot S2 is acquired as a dummy bearer.

Note that here, a slot change instruction was issued to the parent device BS3 that transmitted the slot notification information TJ later, but this is not limited to the above. The parent device control unit 122 can also issue a slot change instruction to the parent device BS2 that transmitted the slot notification information TJ earlier, and control the slot acquired as a dummy bearer for the parent device BS3 to be maintained as is.

Furthermore, the base unit control unit 122 of the main device 1 forms an instruction to change the priority of the slots acquired as dummy bearers to be provided to each of the base units BS1, BS2, and BS3 based on the confirmed information of the terminal-specific slot table 14, and provides this to each base unit (step S45). That is, the process of step S45 is a process of forming and providing, as slot control information CTL, an instruction to change the priority of the slots acquired as dummy bearers to each base unit. In this case, for the base unit BS1, a priority order is formed and provided with a lower priority for slots S1 and S2, and for the base unit BS2, a priority order is formed and provided with a lower priority for slot S2 in addition to slot S0. Also, for the base unit BS3, a priority order is formed and provided with a lower priority for slot S1 in addition to slot S0.

Each of the base units BS1, BS2, and BS3 changes the priority of its own slot table 411 based on the slot control information CTL from the main unit 1 (steps S46, S47, and S48). As a result, the terminal slot table 14 of the main unit 1 manages the state of the slot table 411 of each of the base units BS1, BS2, and BS3, as shown in FIG. 3(B). Therefore, the state of the slot table 411 of each of the base units BS1, BS2, and BS3 is the state of the corresponding base unit column in FIG. 3(B). In this way, the main unit 1 and the base units BS1, BS2, and BS3 of the cordless telephone devices subordinate to the main unit 1 can cooperate to prevent the slots that each base unit acquires as a dummy bearer from overlapping.

[Summary of processing of parent unit BS1 and main unit 1]
The processing performed in the master unit of this embodiment, which operates as described with reference to Fig. 7, and the processing performed in the main device 1 will be summarized below. For simplicity of explanation, the processing in the master unit will be described as the processing in master unit BS1, but similar processing is also performed in master units BS2 and BS3, which are similarly configured.

[Summary of processing of parent unit BS1]
Fig. 8 is a flow chart for explaining the slot-related processing performed by the parent unit BS1. The processing shown in Fig. 8 is repeatedly executed at a predetermined timing by the control circuit 41 of the parent unit BS1 whose power is turned on. When the processing shown in Fig. 8 is executed, the control circuit 41 determines whether or not an event has occurred that notifies the main unit 1 of the slot notification information TJ (step S101).

The determination process in step S101 determines that a notification event has occurred when it is time to transmit slot notification information TJ, when a new dummy bearer is acquired, or when the slot acquired as a dummy bearer is changed. When slot notification information TJ is transmitted periodically, the control circuit 41 measures the transmission interval of slot notification information TJ using a clock circuit provided in the parent unit BS1 (not shown in FIG. 2), and periodically notifies the main unit 1 of the slot notification information TJ based on the measurement result.

In the determination process of step S101, it is determined that an event has occurred that requires notifying the main unit 1 of slot notification information TJ. In this case, the slot notification unit 413 functions to refer to the information stored in the slot table 411, form slot notification information TJ, and transmit this to the main unit 1 (step S102). As described above, the slot notification information TJ includes slot identification information that identifies the slot acquired as a dummy bearer and terminal identification information of the parent unit BS1.

After the process of step S102, or if it is determined in the determination process of step S101 that an event for notifying the main device 1 of the slot notification information TJ has not occurred, the process proceeds to the determination process of step S103. In this case, the control circuit 41 determines whether or not an instruction to change the priority of the slot acquired as a dummy bearer from the main device 1 has arrived as slot control information CTL (step S103). In the determination process of step S103, when it is determined that an instruction to change the priority has arrived from the main device 1, the slot control unit 412 changes the priority of the slot acquired as a dummy bearer in the slot table 411 in accordance with the instruction to change the priority (step S104).

After the process of step S104, or if it is determined in the determination process of step S103 that an instruction to change the priority has not arrived, the process proceeds to the determination process of step S105. In this case, the control circuit 41 determines whether an instruction to change the slot itself has arrived from the main unit 1 as slot control information CTL (step S105). Assume that it has been determined in the determination process of step S105 that an instruction to change the slot has arrived from the main unit 1. In this case, in response to the instruction to change the slot, the slot control unit 412 changes the slot acquired as a dummy bearer to a slot in accordance with the instruction from the main unit 1, and changes the used slot column of the slot table 411 (step S106). That is, the slot change process of step S106 releases the slot before the change, acquires the instructed new slot, and updates this state in the used slot column of the slot table 411.

After the processing of step S106, and if it is determined in the determination processing of step S105 that no slot change instruction has arrived from the main unit 1, the processing shown in FIG. 8 is terminated and the next execution timing is awaited. In this way, the parent unit BS1 realizes the function of notifying the main unit 1 of the slot notification information TJ, the function of changing the priority of the slots acquired as dummy bearers based on the slot control information CTL from the main unit, and the function of changing the slots acquired as dummy bearers.

[Summary of Processing of Main Device 1]
Fig. 9 is a flow chart for explaining the slot management process performed by the main unit 1. The process shown in Fig. 9 is repeatedly executed at a predetermined timing by the control circuit 12 of the main unit 1 that is powered on. The main unit 1 is always in a state in which communication with each parent unit is possible. When the process shown in Fig. 9 is executed, the control circuit 12 judges whether or not it has received slot notification information TJ from a subordinate parent unit (step S201). When it is judged in the judgment process of step S201 that slot notification information TJ has not been received, the process shown in Fig. 9 is terminated and the next execution timing is awaited.

In the determination process of step S201, it is determined that slot notification information TJ has been received from a subordinate parent device. In this case, the management information creation unit 121 functions to execute a process of updating the terminal-specific slot table 14 according to the received slot notification information TJ (step S202). Next, the parent device control unit 122 functions to determine whether or not a change instruction to the parent device is necessary based on the stored information of the updated terminal-specific slot table 14 (step S203). The determination process of step S203 is to determine whether or not it is necessary to change the priority of the slot table due to the acquisition of a slot used as a dummy bearer, or whether or not the acquired slots overlap between parent devices and the slot itself needs to be changed.

When it is determined in the determination process of step S203 that a change instruction is not necessary, the process shown in FIG. 9 is terminated and the next execution timing is awaited. In the determination process of step S203, it is determined that a change instruction to the parent unit is necessary. In this case, the parent unit control unit 122 determines whether or not a change instruction to the parent unit is necessary (step S204). In the determination process of step S204, it is determined that a change instruction to the parent unit is necessary. In this case, the parent unit control unit 122 forms a change instruction to each parent unit that needs to change the priority based on the information in the terminal slot table 14, and transmits this as slot control information CTL to each parent unit that needs to change the priority (step S205). In addition, in step S205, the priority of each parent unit in the terminal slot table 14 is also changed so that it can be managed in accordance with the priority of the parent unit slot table 411.

After the process of step S205, or when it is determined in the determination process of step S204 that it is not necessary to instruct the parent device to change the priority order, the determination process of step S206 is executed. In this case, the parent device control unit 122 determines whether or not it is necessary to instruct the parent device to change the slot (step S206). Assume that it is determined in the determination process of step S206 that it is necessary to instruct the parent device to change the slot. In this case, the parent device control unit 122 forms a slot change instruction for the parent device that requires a slot change based on the information in the terminal-specific slot table 14, and transmits this as slot control information CTL to the parent device that requires the slot change (step S207). Note that in step S207, the slot used by the parent device that requires a change in the slot in the terminal-specific slot table 14 is also changed, and can be managed in accordance with the slot used in the parent device's slot table 411.

After the processing of step S207, or if it is determined in step S206 that a slot change instruction is not required, the processing shown in FIG. 9 is terminated and the next execution timing is awaited. In this way, the main device 1 realizes a function of managing the slots acquired as dummy bearers and the priority of slots to be acquired as dummy bearers in the terminal-specific slot table 14 in the parent device connected to the main device. The main device 1 realizes a function of centrally controlling the change of the priority and the change of slots acquired as dummy bearers based on the information in the terminal-specific slot table 14.

[Effects of the embodiment]
According to the telephone system of the embodiment described above, the main unit 1 can manage the priority of slots acquired as dummy bearers and slots acquired as dummy bearers for each base unit BS1, BS2, and BS3 of the cordless telephone device connected thereto. This allows the main unit 1 to control the slots used as dummy bearers (slots for control signals) by the base units of the cordless telephone devices accommodated in the main unit 1. As a result, overlapping of slots acquired as dummy bearers is prevented in each base unit connected to the main unit 1, and even if a handset moves and enters the wireless communication area of another base unit, it can properly find the slots used as dummy bearers by the other base unit. Therefore, handover of the handset in the standby state can be properly performed.

[Modification]
In the above embodiment, the main unit 1 is connected to the cordless telephone devices 21, 22, and 23, but the present invention is not limited to this. The present invention can be applied to a case where a plurality of cordless telephone devices are connected to the main unit 1. The present invention is suitable for use in a large-scale telephone system in which a large number of cordless telephone devices are connected to the main unit.

In addition, in the above-described embodiment, the slots acquired as dummy bearers and the priority of the slots acquired as dummy bearers are managed for each parent device in the main device 1, but this is not limited to this. At least, if the slots acquired as dummy bearers are managed for each parent device, it is possible to control so that overlaps of slots acquired as dummy bearers do not occur for a long period of time.

However, as in the above-mentioned embodiment, if the priority of the slots acquired as dummy bearers is managed and also managed by each parent device, it becomes possible to efficiently prevent overlapping of slots acquired as dummy bearers between each parent device.

In addition, in the above-described embodiment, the main device 1 performs centralized control of changing the priority order and control of changing the slots acquired as dummy bearers based on the information in the terminal-specific slot table 14. However, this is not limited to this. The main device 1 can also grasp the number of parent devices connected to the main device. Therefore, for example, when the number of parent devices is small, it is possible to increase the number acquired as dummy bearers and control to use a double dummy bearer method or a triple dummy bearer method. Of course, other conditions may be set to control the number of slots acquired as dummy bearers.

The main device 1 can also manage the number of parent devices connected to it and their locations. Therefore, when only one parent device is connected or when the wireless communication areas (radio wave areas) of the parent devices do not overlap, the main device 1 can choose not to control the slots acquired as dummy bearers.

In addition, in the above-described embodiment, the parent devices BS1, BS2, and BS3 connected to the main device 1 spontaneously notify the main device 1 of slot notification information TJ when a specified event occurs, but this is not limited to the above. The main device 1 can also transmit a request to each parent device to provide slot notification information TJ at an appropriate timing, and each parent device can form slot notification information TJ in response and notify the main device 1. For example, the main device 1 can transmit a request to each parent device to provide slot notification information TJ at a specified timing, and each parent device can form slot notification information TJ in response and send it to the main device 1.

In addition, in the above embodiment, an example was described in which a DECT-standard cordless telephone device was used, but the present invention is not limited to this. This invention can be applied when a system is used in which a specific communication channel is divided into frames of a specific time unit between the parent unit and the child unit, each of these frames is further divided into multiple time slots, and wireless communication is performed through a time slot selected for each frame.

[others]
As can be seen from the above description of the embodiment, the slot control means and slot notification means of the base unit in the claims are realized by the slot control unit 412 and slot notification unit 413 of the base unit BS1 in the embodiment. Also, the functions of the management information creation means and base unit control means of the telephone control device in the claims are realized by the management information creation unit 121 and base unit control unit 122 of the main unit 1 in the embodiment.

In addition, by creating a program that executes the process shown in the flowchart of FIG. 8 and loading it into the base unit and making it executable, it is possible to configure the base unit of the cordless telephone device that constitutes the telephone system of this invention. That is, the functions of the slot control unit 412 and slot notification unit 413 of the base unit can also be realized by a program executed by the control circuit 41. In addition, by creating a program that executes the process shown in the flowchart of FIG. 9 and loading it into a telephone control device such as a main unit or SIP server and making it executable, it is possible to configure a telephone control device that constitutes the telephone system of this invention. That is, the functions of the management information creation unit 121 and base unit control unit 122 can also be realized by a program executed by the control circuit 12 of the main unit 1.

1...Main unit, 12...Control circuit, 121...Management information creation unit, 122...Base unit control unit, 14...Terminal slot table, 21, 22, 23...Cordless telephone device, BS1, BS2, BS3...Base unit, HS1, HS2, HS3...Handset, 41...Control circuit, 411...Slot table, 412...Slot control unit, 413...Slot notification unit, 42...Line LSI unit, 43...Synchronization signal generation circuit, 44...Wireless communication circuit, 441...Control unit, 442...TDMA modulation/demodulation unit, 443...Wireless communication unit, 51...Wireless communication circuit, 52...Control circuit, 53...Codec circuit, 511...Control unit, 512...TDMA modulation/demodulation unit, 513...Wireless communication unit

Claims (4)

A telephone system comprising a cordless telephone device including a base unit and a handset, and one or more base units of the cordless telephone device are connected to a telephone control device connected to a wide area network, wherein a predetermined communication channel is divided into frames of a predetermined time unit between the base unit and the handset, each of the frames is further divided into a plurality of time slots, and wireless communication is performed through the time slot selected for each frame,
The parent unit is
a slot table storage means for managing the priority order of each of the plurality of time slots and the time slots selected as control signal slots;
a slot control means for selecting the time slot to be used as a control signal slot in each frame in accordance with the priority order of the slot table storage means when in a standby state, and for transmitting various control signals to the child device;
a slot notification means for notifying said telephone control device of slot notification information including slot identification information of the control signal slot selected by said slot control means and terminal identification information of said own device,
said slot control means, when the slot control information from said telephone control device is information instructing a priority order, is capable of changing the priority order of each of said plurality of time slots in said slot table storage means ;
The telephone control device includes:
a terminal-specific slot table storage means for managing, for each of the master units, the priority order for each of the plurality of time slots and the time slots selected as slots for control signals;
a management information creating means for updating the time slot selected as the control signal slot for the parent device that is the source of the slot notification information in the terminal-specific slot table storage means based on the slot notification information when the slot notification information is received from the parent device, and updating the priority order of each of the multiple time slots of other parent devices;
and a base unit control means for, when the priority order is updated for each of the plurality of time slots based on the information of the terminal-specific slot table storage means created by the management information creation means, forming information indicating the priority order for each base unit and providing this information to the corresponding base unit as the slot control information. 2. The telephone system of claim 1,
the slot control means of the base unit changes the time slot selected as the control signal slot when the slot control information from the telephone control device is an instruction to change the time slot, and changes the time slot selected as the control signal slot in the slot table storage means ;
In the telephone control device,
said management information creating means, when a time slot overlapping with another master unit is selected based on said slot notification information, changes said time slot of one of the master units using the overlapping time slot, and updates the priority order of each of said multiple time slots of the other master unit;
The base unit control means, when the time slot of one of the base units using an overlapping time slot is changed, can form a time slot change instruction for the base unit using the changed time slot and provide this as the slot control information to the corresponding base unit. A base unit of a telephone system configured by connecting one or more base units of a cordless telephone device, the base unit being composed of a base unit and a handset, to a telephone control device connected to a wide area network,
Between the parent device and the child device, a predetermined communication channel is divided into frames of a predetermined time unit, each of the frames is further divided into a plurality of time slots, and wireless communication is performed through the time slot selected for each frame,
said telephone control device comprises: terminal-specific slot table storage means for managing, for each of said base units, the priority order for each of said plurality of time slots and said time slots selected as control signal slots; management information creation means for, when slot notification information is received from said base unit, updating said time slots selected as control signal slots for said base unit which has transmitted said slot notification information in said terminal-specific slot table storage means based on said slot notification information, and updating the priority order for each of said plurality of time slots for other base units; and base unit control means for, when the priority order for each of said plurality of time slots is updated based on information in said terminal-specific slot table storage means created by said management information creation means, forming information indicating the priority order for each of said base units, and providing said information as slot control information to said corresponding base unit;
a slot table storage means for managing the priority order of each of the plurality of time slots and the time slots selected as control signal slots;
a slot control means for selecting the time slot to be used as a control signal slot in each frame in accordance with the priority order of the slot table storage means when in a standby state, and for transmitting various control signals to the child device;
a slot notification means for notifying said telephone control device of said slot notification information including slot identification information of the control signal slot selected by said slot control means and terminal identification information of said own device,
The slot control means is capable of changing the priority of each of the plurality of time slots in the slot table storage means when the slot control information from the telephone control device is information indicating a priority. A telephone control device of a telephone system configured by connecting one or more base units of a cordless telephone device, the base unit being composed of a base unit and a handset, to a telephone control device connected to a wide area network, the telephone control device comprising:
Between the parent device and the child device, a predetermined communication channel is divided into frames of a predetermined time unit, each of the frames is further divided into a plurality of time slots, and wireless communication is performed through the time slot selected for each frame,
the parent unit comprises: a slot table storage means for managing the priority order of each of the plurality of time slots and the time slot selected as a control signal slot; a slot control means for selecting the time slot to be used as a control signal slot in each frame in accordance with the priority order of the slot table storage means when in a standby state, and processing for transmitting various control signals to the child unit; and a slot notification means for notifying the telephone control device of slot notification information including slot identification information of the control signal slot selected by the slot control means and terminal identification information of the parent unit, the slot control means being capable of changing the priority order of each of the plurality of time slots in the slot table storage means when the slot control information from the telephone control device is information indicating priority order;
a terminal-specific slot table storage means for managing, for each of the master units, the priority order for each of the plurality of time slots and the time slots selected as slots for control signals;
a management information creating means for updating the time slot selected as the control signal slot for the parent device that is the source of the slot notification information in the terminal-specific slot table storage means based on the slot notification information when the slot notification information is received from the parent device, and updating the priority order of each of the multiple time slots of other parent devices;
and a base unit control means for, when the priority order is updated for each of the plurality of time slots based on the information of the terminal-specific slot table storage means created by the management information creation means, forming information indicating the priority order for each base unit and providing this information to the corresponding base unit as the slot control information.

Images