Base station for cordless telephone device, and cordless telephone device

Abstract

To make it possible to notify all handsets of incoming calls without a large delay even when the number of handsets accommodated in a base station exceeds the maximum number of handsets capable of simultaneous communication, in the base station for a cordless telephone device and the cordless telephone device that utilize a DECT wireless communication system.SOLUTION: A base station for a cordless telephone device includes DECT control signal generation means 23 and DECT transmission / reception control means 22. The DECT control signal generation means 23 extracts information that needs to be transmitted to a handset from a handset control command transmitted from a telephone control device and generates a handset control signal, and selects an optimal transmission channel for wirelessly transmitting the handset control signal using a DECT system according to the type of the handset control command. The DECT transmission / reception control means 22 performs wireless transmission / reception of the DECT system and DECT TDMA / TDD frame composition / decomposition, and transmits the handset control signal given from the DECT control signal generation means 23 using the optimal transmission channel.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a base station for a cordless telephone device that utilizes the DECT wireless communication system suitable for application to digital cordless telephones, and to the cordless telephone device. [Background technology]

[0002] In Japan, key telephone systems use not only key telephones directly connected to the main unit via a wired transmission line, but also digital cordless telephones (handsets) connected to the main unit via a wireless base station. These digital cordless telephones are highly valued as telephones that can be used anywhere, and are expected to have the same functionality as key telephones.

[0003] In Japan, digital cordless phones have used the second-generation cordless telephone system standard (RCR STD-28), but in 2011 a new standard for broadband digital cordless phones (ARIB STD-T101) was established, making it possible to realize digital cordless phones that comply with J-DECT. J-DECT is a DECT standard localized for Japan, and specifies six frequencies (F1 to F6) within the 1.9 GHz private band (1893.5 MHz to 1906.1 MHz).

[0004] In a key telephone system, the required number of telephone lines are connected to the main unit according to the call volume (the number of communication lines occupied per unit time) in the user's installation environment, and these can be shared and used by each key telephone. For example, in an office with 80 employees, if an average of 10 people make 5-minute calls per hour, the call volume is 0.833 Erlangs, and if the call loss rate (the probability that a call cannot be made because there are no available lines when a call is made) is to be 0.1 or less, then, according to the Erlang B formula, three or more telephone lines should be prepared.

[0005] In such a system, if all or some of the key telephones are to be replaced with digital cordless telephones, the radio base stations can be arranged so that the calling area of ​​one or more radio base stations covers the entire service area (office).

[0006] For example, if an office has four wireless base stations and accommodates 80 digital cordless telephones (handsets), it is desirable that each wireless base station accommodates an average of 20 handsets, and when a call comes in from the telephone line, the call is notified to all handsets via each wireless base station, and the first handset to answer can enter into a call.

[0007] It is also desirable that the notification of the incoming call to each handset be sent as quickly as possible, preferably within 1 to 2 seconds, from the time of the incoming call on the telephone line.

[0008] Also, unlike key telephones, digital cordless telephones (handsets) are not installed in fixed locations but are mobile, so there may be cases where a large number of handset units (for example, 40 units) are concentrated around a specific wireless base station. Even in such cases, it is desirable to notify each handset of an incoming call within 1 to 2 seconds, if possible.

[0009] Patent document 1 describes a cordless telephone device and a wireless communication method, which uses a method of transmitting data in transmission units having an A field for transmitting control data and a B field for transmitting voice data, and when the control unit of the radio transmission circuit of the parent device determines that the device is in a call state, the control unit controls the TDMA modulation / demodulation unit to transmit control data using the A field and voice data using the B field, and when the control unit determines that the device is not in a call state, the control unit controls the TDMA modulation / demodulation unit to transmit control data using at least the B field, thereby making it possible to transmit control data without delay in a wireless communication system using a TDMA / TDD wireless communication method.

[0010] Patent document 2 describes a telephone system, a telephone control device, and a base unit of a cordless telephone device, in which the main unit has a base unit-specific handset management table that is formed based on information in the handset management table provided by the base unit, and a control circuit of the main unit controls the on / off of a scatter mode in which, when there is information to be sent to all handsets connected to the base unit, the information is sent to all the handsets by supplying a control signal to the base unit, and the control circuit refers to the base unit-specific handset management table and controls base units with a predetermined number of connected handsets or less to turn on the scatter mode, and controls base units with more than the predetermined number of connected handsets to turn off the scatter mode, thereby reducing communication time loss that occurs when more handsets than the number that can communicate simultaneously are connected to the base unit of the cordless telephone device. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-177239 [Patent Document 2] Japanese Patent Application Publication No. 2019-146054 Summary of the Invention [Problem to be solved by the invention]

[0012] A base station for a digital cordless telephone system using DECT is generally equipped with one DECT transceiver, and in principle, it is possible to communicate with up to 12 handset units using up to 12 slots. However, in practice, the maximum number of handset units that can communicate simultaneously is limited to 10 or less, to allow for slot switching to accommodate handover handset units and to avoid interference.

[0013] In the cordless telephone device and wireless communication method described in Patent Document 1, control data for a handset is transmitted using the A field when the handset is in a call state and the B field when the handset is not in a call state. Here, control data transmission in the A field refers to data transmission over the Cs channel, and control data transmission in the B field refers to data transmission over the Cf channel. In both cases, the base station and the handset establish a bearer (bidirectional data link) and a data link layer link, and data transmission is performed bidirectionally. Therefore, when the number of handset devices accommodated by a base station is 10 or less, which is the maximum number of handset devices that can communicate simultaneously, transmitting control data using this technology allows control corresponding to the control data to be executed at an appropriate time. However, when the number of handset devices accommodated by a base station exceeds 10, there is a problem in that it is not possible to transmit control data to all of the handset devices. Patent Document 1 does not describe control when the number of handset devices accommodated by a base station exceeds the maximum number of handset devices that can communicate simultaneously.

[0014] In the telephone system, telephone control device, and base unit of the cordless telephone device described in Patent Document 2, when the number of handset devices accommodated in a base station exceeds the maximum number of handset devices that can communicate simultaneously, it is necessary to reconnect the bearer (bidirectional data link) between the base station and each handset device. This is necessary to prevent a large delay in control data transmission to the handset device that is last controlled, considering that the handset authentication and encryption procedures take more than one second. Ultimately, the telephone system, telephone control device, and base unit of the cordless telephone device described in Patent Document 2 not only cannot notify all handset devices of an incoming call, but also has the problem that if the number of handset devices connected to the base station changes over time, the same handset device may sometimes be notified of an incoming call and sometimes not, which may appear to the user to have a malfunction in the handset device.

[0015] The object of the present invention is to solve the above-mentioned problems and to provide a base station for a cordless telephone device using the DECT wireless communication system, and a cordless telephone device, that is capable of notifying all handset units of an incoming call without significant delay, even if the number of handset units accommodated in the base station exceeds the maximum number of handset units that can communicate simultaneously. [Means for solving the problem]

[0016] In order to solve the above problems, the present invention provides a base station for a cordless telephone device, which is configured by selectively using one base station and one handset out of one or more base stations connected to a telephone control device connected to a wide area network and a plurality of handset devices connected to the base station by wireless communication, and which is characterized by comprising: a DECT control signal generation means for extracting information that needs to be transmitted to the handset device from a handset control command transmitted from the telephone control device and generating a handset control signal; and a DECT transmission / reception control means for performing DECT wireless transmission / reception and DECT TDMA / TDD frame synthesis / disassembly, and transmitting the handset control signal provided by the DECT control signal generation means using the optimal transmission channel selected by the DECT control signal generation means.

[0017] Furthermore, the present invention is characterized in that, when the handset control command transmitted from the telephone control device is a line lamp display command, the DECT control signal generating means selects a notification channel as the optimal transmission channel for wirelessly transmitting the handset control signal generated from the handset control command using the DECT system, and the DECT transmission / reception control means transmits the handset control signal using the notification channel without establishing a link.

[0018] The present invention is also characterized in that it includes a base station status management means for generating, as base station status information, information on the number of calling handsets and the number of connected handsets, and two-bit information on whether the number of calling handsets and the number of connected handsets have each reached their upper limit, and further for generating a base station status notification signal that instructs the base station status information to be notified by the MAC information of a beacon, and the base station status notification signal is notified via the DECT transmission / reception control means.

[0019] The present invention also provides a cordless telephone device that is connected to a wide area network and is configured by selectively using one base station and one handset out of one or more base stations connected to a telephone control device of a digital cordless telephone system and a plurality of handset devices connected to the base stations by wireless communication, wherein the base station extracts information that needs to be transmitted to the handset device from a handset control command transmitted from the telephone control device to generate a handset control signal, and further includes DECT control signal generation means for selecting an optimum transmission channel for wirelessly transmitting the handset control signal by the DECT system according to the type of the handset control command, and DECT control signal generation means for selecting an optimum transmission channel for wirelessly transmitting the handset control signal by the DECT system. The system is characterized by comprising: DECT transmission / reception control means for performing TDMA / TDD frame synthesis / decomposition and transmitting the handset control signal provided from the DECT control signal generation means using the optimum transmission channel selected by the DECT control signal generation means; and per-handset paging group number storage means, wherein the handset control signal for the handset is transmitted only on the Bs channel of the multi-frame corresponding to the paging group number of the handset; the handset having a paging group number storage unit, which performs reception operation only on the multi-frame corresponding to the paging group number stored in the paging group number storage unit during discontinuous reception at a cycle of 640 ms.

[0020] Furthermore, in the cordless telephone device of the present invention, when the handset control command transmitted from the telephone control device is a line lamp display command, the DECT control signal generating means provided in the base station selects a notification channel as the optimum transmission channel for wirelessly transmitting the handset control signal generated from the handset control command using the DECT system, and the DECT transmission / reception control means transmits the handset control signal using the notification channel without establishing a link.

[0021] Here, the paging group number of the handset can be determined by the base station in consideration of load balancing during the location registration sequence with the base station, and the determined number can be notified to the handset.

[0022] Alternatively, the paging group number of the handset can be determined by the base station and the handset, respectively, based on the system-specific handset identification information assigned when the handset is incorporated into the digital cordless telephone system.

[0023] Furthermore, the present invention is characterized in that the base station generates, as base station status information, information on the number of calling handsets and the number of connected handsets of the base station, and 2-bit information on whether the number of calling handsets and the number of connected handsets have each reached their upper limit, and further comprises a base station status management means for generating a base station status notification signal that instructs the base station status information to be notified in the MAC information of a beacon, and the handset comprises a handset control unit that operates to select a base station to connect to from among base stations for which the number of calling handsets has not reached its upper limit in the base station status information notified in the beacon in a base station search immediately before link establishment, and to select a base station to connect to from among base stations for which the number of connected handsets has not reached its upper limit in the base station status information notified in the beacon in other base station searches. [Effects of the Invention]

[0024] According to the present invention, in a base station for a cordless telephone device using the DECT wireless communication system, and in the cordless telephone device itself, an optimum transmission channel for wirelessly transmitting a handset control signal using the DECT system is selected according to the type of handset control command, and the handset control signal is transmitted using the optimum transmission channel. Also, if the handset control command is a line lamp display command, a notification channel is selected as the optimum transmission channel, and the handset control signal is transmitted using this notification channel without establishing a link. Therefore, even if the number of handset devices accommodated in the base station exceeds the maximum number of handset devices that can communicate simultaneously, all handset devices can be notified of incoming calls, etc. without significant delay.

[0025] In addition, the base station manages the number of active handsets and the number of connected handsets at the base station based on handset control commands, and generates and notifies a base station status notification signal indicating whether the number of active handsets and the number of connected handsets have reached their respective upper limits. This enables the handset to check the base station status information and select a base station to connect to, thereby achieving optimal load distribution and reducing the increase in the incoming call delay time at the base station until the external call incoming lamp display for all handsets is completed. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 2 is a block diagram showing a basic configuration of an example of a main device. [Figure 2] FIG. 1 is a diagram illustrating an example of a frame format for signal transmission by a TDD (ping-pong transmission) method on a base station transmission line. [Figure 3] 10A and 10B are diagrams illustrating an example of transmission of child device control data having a multi-frame configuration. [Figure 4] FIG. 10 is a diagram illustrating an example of slave unit management in a control unit. [Figure 5] FIG. 1 is a block diagram showing a basic configuration of an embodiment of a base station according to the present invention. [Figure 6] 1 is a block diagram showing a basic configuration of an embodiment of a slave unit according to the present invention; [Figure 7]FIG. 10 is a block diagram showing the basic configuration of another embodiment of a base station according to the present invention. [Figure 8] FIG. 10 is a block diagram showing the basic configuration of another embodiment of a slave unit according to the present invention. [Figure 9] 1 shows an example of the form of a slave unit. [Figure 10] FIG. 2 is a diagram illustrating an example of a slave device state and a state transition. [Figure 11] FIG. 1 is a diagram showing the relationship between the communication distance and the average reception level and the fading drop level in indoor radio wave propagation. [Figure 12] FIG. 2 is a diagram showing the relationship between a callable area and a location registerable area. [Figure 13] FIG. 10 is a diagram illustrating an example of a location registration sequence. [Figure 14] FIG. 10 is a diagram illustrating an example of a call sequence from a handset. [Figure 15] FIG. 10 is a diagram showing an example of a line lamp display sequence. [Figure 16] 10 is a diagram showing an example of a line lamp display message broadcast from a base station using the Bs channel. FIG. [Figure 17] FIG. 10 is a diagram showing an example of an external call incoming call sequence. [Figure 18] FIG. 10 is a diagram illustrating an example of a control sequence in the case of handover. [Figure 19] FIG. 10 is a diagram illustrating an example of a keep-alive sequence from a slave device. [Figure 20] FIG. 10 is a diagram illustrating an example of a transmission operation of paging frames for four paging groups. [Figure 21] FIG. 10 is a diagram showing another example of the transmission operation of paging frames for four paging groups. [Figure 22] FIG. 1 is a diagram showing one form of station placement design for a cordless telephone device. [Figure 23] FIG. 1 is a diagram showing the arrangement of radio resources in J-DECT. [Figure 24] The frame format of a DECT frame is shown, where (a) shows a short frame and (b) shows a long frame. [Figure 25] FIG. 1 is a diagram illustrating an example of a frame format of a DECT multiframe. [Figure 26] FIG. 10 is a diagram showing a frame format of base station ID information Nt. [Figure 27] FIG. 10 is a diagram showing the frame format of system information Qt. [Figure 28] FIG. 10 is a diagram illustrating an example of the correspondence between a Qt header and system information. [Figure 29] FIG. 10 is a diagram showing a frame format of MAC control information Mt. [Figure 30] FIG. 10 is a diagram illustrating an example of the correspondence between an Mt header and a message type. [Figure 31] FIG. 10 is a diagram illustrating an example of the correspondence between Mt commands and MAC control messages. [Figure 32] FIG. 10 is a diagram showing a frame format of paging information Pt. [Figure 33] FIG. 10 is a diagram illustrating an example of the correspondence between a Pt header and Bs channel information. [Figure 34] 10 is a diagram showing an example of the correspondence between information types of Pt short pages and MAC information. FIG. [Figure 35] 10A and 10B are diagrams illustrating an example of power-saving wireless operation of a DECT slave unit in a communication state. [Figure 36] FIG. 10 is a diagram illustrating an example of power-saving wireless operation of a DECT slave unit in an idle lock state. [Figure 37] FIG. 10 is a diagram illustrating an example of power-saving wireless operation of a DECT handset when receiving multiple paging frames. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will now be described with reference to the drawings.

[0028] Since the present invention relates to the control of a digital cordless telephone using the DECT wireless communication system, first, a brief description will be given of the DECT standard for control related to the present invention.

[0029] FIG. 23 shows the arrangement of radio resources in J-DECT.

[0030] The DECT standard uses the TDMA-TDD method. As shown in Figure 23, J-DECT's radio resource allocation is structured as a 10-ms frame on the time axis, with 12 slots for downlink (base station → handset) and 12 slots for uplink (handset → base station). Six frequencies (F1 to F6) are specified on the frequency axis. While it shares the same frequency band as privately operated second-generation cordless telephone (PHS) systems, the PHS control channel is a fixed frequency, and interference with this could cause PHS handset control failures. Therefore, the ARIB STD-T101 PHS protection regulations stipulate that after powering on, J-DECT base stations check for the presence or absence of PHS control channel signals before transmitting. If signals are detected, the F3 and F4 channels are not used.

[0031] Channels other than F3 and F4, which overlap with the PHS control channel, are shared with PHS for free channel detection. However, the free channel detection interval for PHS systems is often around 300us, and dummy bearers may slip through this interval and cause interference that is invisible to the PHS side. Therefore, the ARIB STD-T101 PHS Protection Regulation stipulates that J-DECT base stations, after powering on and before transmitting, check for the presence of PHS control channel signals, and if they determine that signals are present, they avoid transmitting dummy bearers on F2 and F6 channels as much as possible. This is because many PHS products avoid using the F1 and F5 channel bands to avoid market interference, but they do use the F2 and F6 channel bands, and if a J-DECT base station transmits a dummy bearer on these bands, there is a risk of market interference.

[0032] In DECT, when transmitting wirelessly, the handset and base station detect available channels and select and use a channel (combination of frequency channel and slot) with a low reception (interference) level.

[0033] FIG. 24 shows the frame format of a DECT frame.

[0034] As shown in Figures 24(a) and 24(b), DECT has short frames called dummy bearers with a duration of 83.3 us and long frames called traffic bearers with a duration of 368.1 us. The former are frames used by base stations in idle (non-communicating) states to transmit beacons, and the latter are frames used for one-to-one communication between a base station and a handset.

[0035] The beacon (dummy bearer) transmitted by an idle base station is a one-way broadcast channel for downlink only, and is transmitted using one or two downlink radio resources (channels) per base station. Two beacons are transmitted per base station to avoid a situation where a mobile device cannot handover to the base station if the beacon transmission slot of the destination base station matches the call slot of the mobile device when handing over. The two beacons are transmitted in different slots. On the other hand, the traffic bearer used for one-to-one communication between a base station and a mobile device is a bidirectional channel, and uses a pair of slots spaced 5 ms apart (for example, slot 1 and slot 13). Note that a base station in communication can transmit both a dummy bearer for beacons and a traffic bearer, and can also transmit beacon control data using the A-Field in the traffic bearer.

[0036] In a digital cordless telephone system using DECT, traffic bearers are transmitted for each one-to-one communication between a base station and a handset, and up to twice the number of base stations or dummy bearers. The transmission rights for both dummy bearers and traffic bearers are acquired in the same way through free channel detection. From the viewpoint of efficient frequency utilization, the free channel detection level is set so that channels used by surrounding base stations and their handset units can be reused and used. During periods of traffic congestion, there is a possibility that some handset units will not be able to receive dummy bearers due to co-channel interference from traffic bearers from surrounding base stations. Therefore, it is desirable to use the minimum number of traffic bearers necessary.

[0037] FIG. 25 shows an example of a frame format of a DECT multiframe.

[0038] This multi-frame structure is used to broadcast tail data (40 bits) using beacons in DECT. One multi-frame has a time length of 160 ms and is made up of 16 frames (frame 0 to frame 15).

[0039] The tail data (40 bits) broadcast in the beacon is classified into base station ID information Nt, system information Qt, MAC control information M, paging information Pt, and upper layer control information Ct depending on its type. Such beacon type information is stored in the header information of the dummy bearer A-field.

[0040] FIG. 26 shows a frame format of base station ID information Nt that reports base station ID information.

[0041] The base station ID information Nt includes an equipment manufacturer ID (EIC), a system ID (FPN), and a base station ID (RPN). Each user is assigned a different system ID, and the base station within the user's system is identified by the base station ID.

[0042] FIG. 27 shows a frame format of system information Qt that notifies system information, and FIG. 28 shows an example of the correspondence between the Qt header and system information.

[0043] In addition to basic information such as available RF carrier information, RF carrier / slot information for the Qt frame, and primary scan frequency information, which is the base station's free channel detection frequency information, the system information Qt also includes extended RF carrier information, multiframe number information, base station transmission power information, and unique system information.

[0044] Fig. 29 shows the frame format of MAC control information Mt that broadcasts MAC control information, Fig. 30 shows an example of the correspondence between Mt headers and message types, and Fig. 31 shows an example of the correspondence between Mt commands and MAC control messages.

[0045] Fig. 32 shows a frame format of paging information Pt that broadcasts paging information, Fig. 33 shows an example of the correspondence between the Pt header and Bs channel information, and Fig. 34 shows an example of the correspondence between the information type of the Pt short page and MAC information.

[0046] The paging information Pt broadcasts data on the Bs channel (slow broadcast channel) and MAC information. The Bs channel can broadcast paging information and unique information to notify that there is downlink data addressed to a specific mobile station. MAC information includes blind slot information (unavailable slots of the base station), base station status information (BUSY, etc.), and available frequency channel information, and the type of MAC information broadcast in the frame is stored in the information type of the dummy bearer A-field.

[0047] The paging information Pt frame includes a short page (Fig. 32(a)) that broadcasts 20 bits of Bs channel data and MAC information, and a full page (Fig. 32(b)) that broadcasts only 36 bits of Bs channel data. A long page can also be used, which combines multiple full pages to broadcast 36 × N bits of Bs channel data. The frame type information of the paging information Pt is transmitted in the Pt header.

[0048] In the DECT standard, the frame number is specified as 28 bits, incremented by 1 for each frame, and goes through a cycle approximately once a month. The upper 24 bits are called the multi-frame number.

[0049] In a digital cordless telephone system using the DECT system, the frame numbers and multiframe numbers are generally synchronized between base stations.

[0050] Paging information Pt is transmitted in frame 0, and battery-powered, power-saving handset devices can receive only frame 0 discontinuously at 160 ms intervals. The DECT standard specifies that a base station must transmit the same beacon information in four consecutive multi-frames to enable discontinuous reception at 640 ms intervals. In other words, power-saving handset devices can receive only frame 0 discontinuously at 640 ms intervals.

[0051] If there are multiple pieces of paging information Pt, up to six pieces of paging information Pt can be transmitted within one multi-frame. The presence or absence of subsequent paging information Pt within the same multi-frame is indicated by the first bit of the Pt header, and the power-saving slave device transitions to a sleep state after receiving all of the paging information Pt.

[0052] Figure 35 shows an example of power-saving radio operation of a DECT handset in a communication state, Figure 36 shows an example of power-saving radio operation of a DECT handset in an idle lock state, and Figure 37 shows an example of power-saving radio operation of a DECT handset when receiving multiple paging frames.

[0053] Furthermore, if there is no particular paging information, the base station can transmit base station ID information Nt instead of paging information Pt. The base station ID information Nt is used by the mobile device when searching for a base station. Furthermore, system information Qt is always transmitted in frame 8, and base station ID information Nt is always transmitted in frame 14.

[0054] Furthermore, during one-to-one communication between a base station and a mobile device, even-numbered frames (frame 1, frame 3, ... frame 11) are used as upper layer control information Ct, a data link is established between the base station and the mobile device on the upper layer control information Ct, and low-speed control information can be transmitted in both directions using a bidirectional low-speed control channel Cs on the data link. Note that the upper layer control information Ct is a bidirectional channel, and the upper layer control information Ct is also transmitted using the A-Field for the uplink traffic bearer.

[0055] A traffic bearer is used for one-to-one communication between a base station and a handset, and the Cs channel is a low-speed channel that uses the tail (40 bits) of the A-field of the traffic bearer, but it is also possible to use the high-speed Cf channel that uses the B-field (320 bits) of the traffic bearer. For example, when a call is in progress, voice data is transmitted in the B-field, so control data is transmitted in the Cs channel in the A-field, and when there is no call, high-speed control data can be transmitted using the Cf channel in the B-field.

[0056] The even-numbered frames (frame 1, frame 3, etc.) are also used for bidirectional transmission of MAC control information Mt for MAC access control. When performing one-to-one communication between a base station and a mobile device, it is first necessary to establish a bearer (bidirectional data link) using the MAC control information Mt. The MAC control information Mt is also used in encryption procedures and handovers.

[0057] In the dummy bearer, if there is no MAC control information, the base station ID information Nt can be transmitted in even-numbered frames (frame 1, frame 3, etc.). The base station ID information Nt is used when the mobile device searches for a base station.

[0058] Taking the above DECT standard into consideration, the present invention enables the transmission of incoming call and incoming call lamp information to all handset units without significant delay, even if the number of handset units accommodated in a base station exceeds the maximum number of handset units that can communicate simultaneously.

[0059] The present invention will now be described with reference to the drawings.

[0060] The present invention particularly relates to a cordless telephone device configured by selectively using one base station and one handset among one or more base stations connected to a telephone control device (main unit) connected to a wide area network and multiple handset units connected to the base station via a wireless communication method, and the base station, but first we will explain the main unit connected to the wide area network.

[0061] FIG. 1 is a block diagram showing the basic configuration of an example of a main device connected to a wide area network.

[0062] The main unit 10 includes a central office interface unit (central office I / F unit) 11, an extension interface unit (extension I / F unit) 12, a clock generating unit 13, a circuit switching unit 14, and a control unit 15. For simplicity of explanation, only the necessary components are shown here. This also applies to the following figures.

[0063] L (L is a natural number greater than or equal to 1) telephone lines (office lines) are connected to the central office I / F unit 11, and central office calls and incoming calls can be made simultaneously up to L lines. M (M is a natural number greater than or equal to 1) base station transmission lines are connected to the internal line I / F unit 12, and through these, a maximum of M (M is a natural number greater than or equal to 1) base stations can be accommodated.

[0064] The audio data stored in main unit 10 is, for example, an audio coded signal such as a PCM codec signal. A PCM codec signal is 64 kbps audio data that is generated by quantizing an audio signal at 14 bits at 8 kHz (125 μs intervals) and then nonlinearly compressing the quantized signal to 8 bits.

[0065] The clock generator 13 generates an audio multiplex clock that is fast enough to circuit-switch the audio signals on the telephone line and extension lines, and supplies it to the central office I / F 11 and extension I / F 12. The multiplexed audio signal generated using this clock is applied to the circuit switching unit 14, where it is circuit-switched based on control information for outgoing and incoming calls on the extension lines. The clock generator 13 also generates an audio codec frame pulse with a 125 μs period and supplies it to the central office I / F and extension I / F, respectively, which can be used to perform circuit switching on a sample-by-sample basis for the audio signal. Furthermore, the clock generator 13 generates an inter-base station synchronization timing pulse for DECT inter-base station synchronization. This inter-base station synchronization timing signal is supplied to each base station via the base station transmission path, thereby achieving inter-base station synchronization.

[0066] In addition, in digital cordless telephone systems that use the DECT wireless communication method, not only multi-frame synchronization between base stations but also frequency channel synchronization for detecting available channels is required, so timing synchronization with a period of 160 ms x (number of frequency channels) is required, and if the number of frequency channels is 6, timing information with a period of 960 ms is supplied.

[0067] The base station transmission path transmits two-way voice data with the handset connected to the base station for communication, two-way control data for all handset connected to the base station, and timing information for synchronization between DECT base stations.

[0068] FIG. 2 shows an example of a frame format for signal transmission in a TDD (ping-pong) system on a base station transmission line.

[0069] Here, downlink transmission and uplink transmission are provided, and a guard period is provided between the uplink transmission and the downlink transmission in consideration of the transmission delay time on the base station transmission path.

[0070] The TDD system's period (frame time length) is set to an integer multiple of 125 us to match the division of the audio data. Downstream transmission data consists of synchronization bits, one or more channels of audio data, downstream common control data, and DECT inter-base station synchronization bits (not shown). The same applies to upstream transmission data.

[0071] Since the control data for the slave device is usually several bytes to several tens of bytes and a transmission delay of several hundred milliseconds is acceptable, multiple TDD frames may be concatenated to form a multiframe, and the control data may be transmitted in units of multiframes. In this case, a multiframe synchronization bit can be used. The time length of a multiframe is set to, for example, several tens of milliseconds.

[0072] FIG. 3 shows an example of transmission of handset control data in a multi-frame configuration.

[0073] Here, the multi-frame is configured with 50 bytes of control data per multi-frame.

[0074] Frame synchronization has a period of an integer multiple of 125 us, multi-frame synchronization has a period of about several tens of ms, and DECT inter-base station synchronization has a period of, for example, 960 ms. DECT inter-base station synchronization timing information may be transmitted using a frame synchronization bit pattern.

[0075] The control data is generated in the control unit 15. The two-way control data stores control commands for each control sequence between the main unit 10 and the base station. The control data can include ID information for identifying the handset to be controlled, and can also include information such as a call number assigned when making or receiving a call.

[0076] The control unit 15 manages and updates the connected base station information, call status, whether or not ringing is specified, the station line key assignment, and the lamp status of the assigned station line key for all the handset units in the system. When the lamp status of the station line key of the handset unit changes, a line lamp display command is issued to that handset unit.

[0077] FIG. 4 shows an example of slave unit management in the control unit 15. In FIG.

[0078] Here, base station 1 accommodates handset units with handset IDs "100" to "105", and these handset units can communicate through base station 1, while base station 2 accommodates handset units with handset IDs "106" to "107", and these handset units can communicate through base station 2. Furthermore, handset unit with handset ID "100" is assigned lines "5239" and "5396", but its current call control state is "idle", and the line lamps for lines "5239" and "5369" are both "off". Furthermore, handset unit with handset ID "101" is assigned lines "5211" and "5169", but its current call control state is "in call", and the line lamp for line "5169" is "green" (in call). This indicates that the user of the handset with handset ID "101" is making a call through line "5169." Furthermore, handset units with handset IDs "102" to "107" are assigned line "5169", but because the user of handset unit with handset ID "101" is already in a call on that line, the line lamp status of those handset units is "red lit", indicating that the line is being used by another handset. Handset units with handset IDs "101" to "107" are also assigned line "5211". The call control status for that line is currently "incoming call", and the line lamp status is "flashing red" (incoming call), indicating that there is an incoming call through line "5211".

[0079] FIG. 5 is a block diagram showing the basic configuration of an embodiment of a base station according to the present invention.

[0080] Although only the basic configuration of base station 1 (20) is shown here, other base stations have the same basic configuration. The digital telephone device of the present invention is configured by selectively using one of these base stations and one of the handset units described below, and functions as one cordless telephone.

[0081] The base station 20 includes a base station transmission path termination unit 21, a DECT transmission / reception control unit 22, a DECT control signal generation unit 23, and a base station status management unit 24.

[0082] The base station transmission path termination unit 21 decomposes and combines TDD frames transmitted over the base station transmission path. K (K is a natural number equal to or greater than 1) pieces of bidirectional audio data are transmitted over the base station transmission path, and these bidirectional audio data are serially transmitted to the DECT transmission / reception control unit 22 via, for example, a codec interface.

[0083] For the codec interface, a clock for the multiplexed audio codec and an audio codec frame pulse are also generated in the base station transmission path termination unit 21 and applied to the DECT transmission / reception control unit 22 .

[0084] Furthermore, predetermined timing information (inter-base station synchronization timing pulse) for DECT inter-base station synchronization, for example, with a period of 960 ms, is also output from the base station transmission path termination unit 21 and applied to the DECT transmission / reception control unit 22 .

[0085] In addition, the base station transmission path termination unit 21 synthesizes or decomposes the bidirectional control data as handset control commands in multi-frame units of the base station transmission path, and applies the data to the DECT control signal generation unit 23, for example, via a bidirectional serial interface.

[0086] The DECT control signal generator 23 analyzes the command type of the handset control command received from the base station transmission path termination unit 21 via the serial interface, determines the optimum DECT transmission channel according to the command type, and notifies the DECT transmission / reception controller 22 of this as a DECT transmission channel selection signal. At the same time, the DECT control signal generator 23 applies the control information of the handset control command to the DECT transmission / reception controller 22 as a handset control signal either directly or by converting it into a format compatible with the DECT transmission channel.

[0087] Conversely, DECT transmission / reception control unit 22 receives control information from the handset via the wireless transmission path and applies it as a handset control signal to DECT control signal generation unit 23. DECT control signal generation unit 23 converts the format of this signal into a handset control command specified by main unit 10, and applies it to base station transmission path termination unit 21. The handset control command is notified to main unit 10 via the base station transmission path.

[0088] DECT transmission channels include the Cs and Cf channels, which transmit control data after establishing a one-to-one link between the base station and the handset, and the Bs channel, which broadcasts control data using a beacon without establishing a link. The Bs channel can broadcast paging information and unique information to notify a specific handset that downlink data is available. Therefore, for line lamp display messages and incoming call messages that must be notified to all handset units connected to the base station, the Bs channel is selected, which can broadcast control data using a beacon without establishing a link and without being limited by the maximum number of handset units that can communicate simultaneously. For other control information, the Cs or Cf channel is selected.

[0089] The base station status management unit 24 acquires handset control commands sent and received between the base station transmission path termination unit 21 and the DECT control signal generation unit 23, and further acquires from the DECT transmission / reception control unit 22 keep-alive signals that the handset periodically sends to the base station to indicate that it is in range, manages the base station status based on these, and applies a base station status notification signal to the DECT transmission / reception control unit 22.

[0090] For example, when a response command to a handset is detected in an outgoing call sequence from the handset, the number of handsets in communication may be increased by 1, and when a disconnect command is detected, the number of handsets in communication may be decreased by 1. Similarly, when a response command from a handset is detected in an incoming call sequence to the handset, the number of handsets in communication may be increased by 1, and when a disconnect command is detected, the number of handsets in communication may be decreased by 1. Furthermore, when a handset is handed over, the base station from which the handset has moved may decrease the number of handsets in communication by 1 when a call disconnect command from the main unit is detected, and the base station to which the handset has moved may increase the number of handsets in communication by 1 when a response command from the main unit is detected.

[0091] Similarly, for example, the number of connected handset devices may be increased by one when a location registration acceptance command from the main unit is detected in the location registration sequence from the handset. Furthermore, the number of connected handset devices may be decreased by one when a keep-alive signal transmitted from the handset at a fixed cycle T1, for example, every 30 seconds, continues to be unavailable for a fixed period T2, for example, three minutes. Furthermore, when a handset performs handover, the source base station may decrease the number of connected handset devices by one when a call disconnection command from the main unit is detected, and the destination base station may increase the number of connected handset devices by one when a response command from the main unit is detected. Furthermore, although not shown, when an idle handset device that is not in a call roams between base station areas, after accepting location registration from the destination base station, the main unit may instruct the source base station to delete the location registration of the handset, and the base station that receives this instruction may decrease the number of connected handset devices by one.

[0092] As a result, the base station status management unit 24 manages the number of calling handsets and the number of connected handsets at the base station 20, and based on this generates 2-bit information indicating whether the number of calling handsets and the number of connected handsets have each reached their upper limit values.From this, a base station status notification signal is generated that instructs notification to be made in the MAC information of the beacon and applied to the DECT transmission / reception control unit 22, so that the base station status can be reported in the MAC information of the beacon transmitted from the base station 20.

[0093] In the base station search immediately before establishing a link, the handset checks the base station status information in the MAC information broadcast by the beacon and selects a base station to connect to from among base stations where the number of handset devices in communication has not reached the upper limit, and in other base station searches, checks the base station status information in the MAC information broadcast by the beacon and selects a base station to connect to from among base stations where the number of handset devices connected has not reached the upper limit, thereby achieving optimal load balancing. This reduces the increase in call delay time, which is the time it takes for the outside call lamp to be displayed for all handset devices at that base station when a large number of handset devices are connected to a specific base station.

[0094] FIG. 6 is a block diagram showing the basic configuration of an embodiment of the slave unit 1 (30) according to the present invention.

[0095] Although only the basic configuration of one handset is shown here, N handset units (N is a natural number greater than or equal to 1) are provided per system, and the other handset units have the same basic configuration. This allows each handset to make and receive calls via any of the base stations. The handset 30 of this embodiment includes a DECT transmission / reception control unit 31, a handset control unit 32, an audio codec 33, an office line key 34, a ringer 35, an LCD display unit 36, a microphone 37, a speaker 38, and a numeric keypad 39.

[0096] The DECT transmission / reception control unit 31 performs transmission and reception of DECT radio signals, GFSK or differential PSK modulation and demodulation, TDMA frame synthesis, TDMA frame decomposition, search processing when searching for a base station, and radio state management.

[0097] The handset control unit 32 transmits and receives handset control commands to and from the DECT transmission / reception control unit 31, and controls each unit of the handset 30.

[0098] The audio codec 33 transmits and receives audio codec signals to and from the DECT transmission / reception control unit 31, and also receives an audio codec clock and audio codec frames from the DECT transmission / reception control unit 31 to encode / decode audio. A microphone 37 and a speaker 38 are connected to the audio codec 33, and an audio signal uttered on the handset side is converted into an electrical signal by the microphone 37, sampled at a predetermined rate, for example, 8 kHz, by an AD converter provided in the audio codec 33, and the transmission band is further compressed by the audio codec 33. For example, a linear PCM signal that has been AD converted at 14 bits may be compressed to 8 bits by u-law PCM or A-law PCM, and then further compressed to 4 bits by ADPCM.

[0099] The DECT standard supports audio codecs such as 32 kbps ADPCM for narrowband audio and 64 kbps u-law PCM and 64 kbps G.722 for wideband audio. Narrowband audio uses one slot each for uplink and downlink, while wideband audio uses two slots each for uplink and downlink. Handset 30 may use either narrowband audio or wideband audio.

[0100] The voice signal uttered by the other party in the call is converted into an analog signal by a DA converter provided in the voice codec 33 and output from a speaker 38. The voice codec 33 is supplied with a voice codec clock and a voice codec frame pulse indicating the starting point of one sampling of data from the DECT transmission / reception control unit 31, and bidirectional voice codec signals are transmitted between the voice codec 33 and the DECT transmission / reception control unit 31.

[0101] The handset control unit 32 is connected to an office line key 34, a ringer 35, an LCD display unit 36, a numeric keypad 39, and the like, and controls the office line key lamp display, the ringer sound, and the LCD display in response to handset control signals. Information on pressing the office line key 34 or the numeric keypad 39 is applied to the DECT transmission / reception control unit 31 as a handset control signal and processed in a control sequence. The control sequence will be described later.

[0102] 7 is a block diagram showing the basic configuration of another embodiment of the base station 1 (20) according to the present invention. In FIG. 7, the same parts as in FIG. 5 are assigned the same reference numerals.

[0103] In this embodiment, the base station 20 includes a per-handset paging group number storage unit 25. The per-handset paging group number storage unit 25 stores paging group numbers for all handset units connected to the base station 20 and applies the paging group numbers to the DECT control signal generation unit 23. The DECT control signal generation unit 23 then applies handset control signals for each handset unit to the DECT transmission / reception control unit 22 at multi-frame timing corresponding to the paging group. The base station 20 also includes a base station status management unit 24. Similar to the base station status management unit 24 in FIG. 5 , the base station status management unit 24 acquires a base station status signal from a handset control command and further acquires a keep-alive signal that the handset unit periodically transmits to the base station from the DECT transmission / reception control unit 22 to indicate that it is within range. Based on these signals, the base station status management unit 24 manages the base station status, generates a base station status notification signal, and applies the signal to the DECT transmission / reception control unit 22.

[0104] Furthermore, the DECT control signal generating unit 23 is supplied with a multi-frame timing pulse indicating the start timing of a multi-frame with a 160 ms period and information on the lowest 2 bits of the multi-frame number.

[0105] The two lowest bits of the multiframe number have a repetition cycle of 640 ms, and the DECT control signal generator 23 performs control such that, for example, a handset control signal to be transmitted using the Bs channel to handset units in paging group 1 is applied to the DECT transmission / reception controller 22 in a multiframe in which the two lowest bits of the multiframe number are "00", and a handset control signal to be transmitted using the Bs channel to handset units in paging group 2 is applied to the DECT transmission / reception controller 22 in a multiframe in which the two lowest bits of the multiframe number are "01". As a result, handset control signals to be transmitted using the Bs channel can be notified to all handset units within 640 ms using different multiframes for handset units belonging to different paging groups.

[0106] In each paging group, up to six Bs channels can be transmitted within one multiframe period. That is, for up to 24 handset units, each Bs channel can be transmitted within 640 ms.

[0107] 8 is a block diagram showing the basic configuration of another embodiment of the slave unit 1 (30) according to the present invention. In FIG. 8, the same parts as in FIG. 6 are denoted by the same reference numerals.

[0108] The handset 30 of this embodiment operates in conjunction with the base station 20 of Figure 7, and is equipped with a paging group number memory unit 40 for storing the paging group number of the handset 30, and the paging group number information stored here is applied to the handset control unit 32.

[0109] During intermittent reception at a 640 ms cycle, the handset control unit 32 refers to the multiframe number notified by the beacon and controls the DECT transmission / reception control unit 31 to receive only the multiframe corresponding to the paging group number of the handset at a 640 ms cycle.

[0110] FIG. 9 shows an example of the form of the slave unit.

[0111] The handset here has eight line keys LK1 to LK8, each of which corresponds to one telephone line.

[0112] As with key telephones, each line key is equipped with an LED to indicate the line's status (free, in use, etc.), allowing the user to see the status of free lines at a glance. For example, if the line key for a free line is off and the line key for a line currently in use is on, the user can select the off line to make an outside call.

[0113] When an outside call comes in, the line key of all handsets that have that telephone line assigned to it will flash to notify the call, and only the handset that answers first will be able to talk. Also, like a key telephone, you can put the call on hold or transfer it after talking.

[0114] Furthermore, just like with key telephones, when an outside call comes in, not only does the corresponding line key flash to notify the caller, but it can also ring a handset that has been designated as a ringing terminal. However, it is desirable to establish a link with the ringing handset so that the call can be made immediately when the user answers.

[0115] However, since there is a possibility that some handset may not be able to receive the dummy bearer due to co-channel interference from the traffic bearer during traffic congestion, it is desirable to limit the use of traffic bearers to the minimum necessary, and from this perspective, it is also desirable to limit the number of ringing handset units to the minimum necessary.

[0116] FIG. 10 shows an example of the slave device states and state transitions.

[0117] In the initial state after power-on, each handset performs a base station search operation at regular intervals. In the base station search, for example, the handset can receive base station ID information Nt broadcast by each base station using a dummy bearer, select the base station with the highest reception level, and connect to it.

[0118] When each mobile device registers its location with a base station, it enters an idle-locked state, which means that it is connected to a base station but only receives beacons and is not engaged in two-way communication with the base station.

[0119] As described above, after powering on, each handset registers its location with one of the base stations and becomes able to make and receive calls through that base station. This is called connecting the handset to a base station. In other words, each handset becomes able to make and receive calls through the base station to which it is connected.

[0120] When a slave unit communicates with a base station, it establishes a link and transitions to a communication locked state, in which bidirectional communication with the base station is performed using a traffic bearer.

[0121] Even in a communication locked state, a search for a communicating base station can be performed when communication quality deteriorates or at predetermined time intervals, and if a new base station with better wireless communication capabilities is found, a link is established with the new base station, transitioning to a handover state in which a double link is established, and then the old link is disconnected and transitioning to a communication locked state with the new base station. In other words, as a handset in an idle locked state moves, it may reconnect to a base station with better wireless communication capabilities, and even during a call, as a handset moves, it may reconnect to a base station with better wireless communication capabilities. The former is called roaming, and the latter is called handover.

[0122] Before registering its location, the handset searches for nearby base stations and basically registers its location with the base station that has the highest reception level of the beacons transmitted every 160 ms. Cordless phones use radio waves in the 1.9 GHz band, but multipath fading generally occurs when microwave radio waves are propagated indoors, and it is known that the reception level fluctuates over time by about 10 to 20 dB.

[0123] Figure 11 shows the relationship between communication distance and average received signal level and fading level in indoor radio wave propagation. Note that in Figure 11, the average received signal level was calculated using the Rec. ITU-R P.1238-6 indoor propagation model. This model takes into account loss due to partitions in an office, etc.

[0124] To ensure good call quality, it is desirable to maintain a minimum receiving sensitivity or higher and be able to communicate without wireless transmission errors even when the receiving level drops due to fading.On the other hand, with regard to location registration, location registration is possible if the receiving level remains high and is above the minimum receiving sensitivity even when the receiving level fluctuates due to fading.

[0125] If we consider the former to be the area where communication is possible and the latter to be the area where location registration is possible, the radius of the area where location registration is possible is generally much larger than the area where communication is possible. In a typical indoor propagation model, the average reception level drops by 6 dB when the communication distance doubles. In this propagation model, a difference of 10 to 20 dB in reception level translates to a communication distance of more than four times.

[0126] Typically, in cordless phones, base stations are placed (station placement design) so that the entire service area is covered by multiple calling areas. In this case, each location registration area includes surrounding calling areas, and in many cases, a search for surrounding base stations will find all or most of the base stations that can be registered.

[0127] FIG. 12 shows the relationship between the call coverage area and the location registration area.

[0128] Here, the communication area of ​​the central base station and six surrounding base stations (shown by solid lines) and the location registration area of ​​the central base station (shown by dashed lines) are shown.

[0129] In location registration, the base station with the highest beacon reception level is basically selected from among the base stations capable of location registration found in the surrounding base station search, and location registration is performed. If location registration cannot be performed with the base station with the highest beacon reception level, location registration will be performed with a surrounding base station capable of location registration, but wireless communication is basically possible between the base station capable of location registration and the handset, so call origination and reception control is possible.

[0130] If location registration is not possible with the base station with the highest beacon reception level and location registration is performed with a neighboring base station where location registration is possible, it may be possible that the mobile terminal is outside the call area of ​​the base station where location registration is performed. However, if such a mobile terminal makes or receives a call and enters a call state, and the call state is not good, it will hand over to an adjacent base station and enter the call area.

[0131] Next, a control sequence in the cordless telephone device according to the present invention will be described, with reference to Figures 1, 5 (Figure 7), and 6 (Figure 8) as appropriate.

[0132] FIG. 13 shows an example of a location registration sequence.

[0133] The location registration sequence uses the Cs channel or Cf channel for control data transmission after establishing a one-to-one link between the base station 20 and the mobile device 30. The location registration sequence is performed by the mobile device 30 immediately after power-on or by the mobile device 30 after moving into an adjacent base station zone, by establishing a radio link.

[0134] The handset 30 that is to register its location first transmits an access request defined in the DECT MAC layer standard (ETSI EN 300-175-3) to the base station 20 that is to register its location. The base station 20 that is to register its location is, for example, the base station 20 that had the highest beacon reception level in the immediately preceding base station search.

[0135] When the handset 30 receives a bearer confirmation specified in the DECT MAC layer standard from the base station 20, it establishes a link in the data link layer in accordance with the procedure specified in the DECT DATA LINK layer standard (ETSI EN 300-175-4), and then transmits a location registration request message to the base station 20 using the Cs channel or Cf channel.

[0136] In base station 20, the message is output as a handset control signal from DECT transmission / reception control section 22 and applied to DECT control signal generation section 23. DECT control signal generation section 23 converts the received location registration request message into a handset control command for main unit 10, and then transmits it to main unit 10 over the base station transmission path via base station transmission path termination section 21.

[0137] The location registration request message generated by handset 30 may be the same as the handset control command from main unit 10, or may have unnecessary headers removed to reduce the size of the transmitted data.

[0138] When the main unit 10 receives a location registration request from the handset 30, it issues an authentication request command to the handset 30. This command is transmitted to the base station 20 via the base station transmission path. The authentication request command is output from the base station transmission path termination unit 21 and applied to the DECT control signal generation unit 23 as a handset control command.

[0139] The DECT control signal generator 23 outputs the authentication request command itself, or a command with a reduced transmission data size obtained by removing the header and the like, as a handset control signal and applies it to the DECT transmission / reception controller 22. At the same time, the DECT control signal generator 23 also outputs a signal instructing the selection of the Cs channel or the Cf channel as a DECT channel selection signal and applies it to the DECT transmission / reception controller 22.

[0140] Based on the DECT channel selection signal, the DECT transmission / reception control unit 22 uses the Cs channel or the Cf channel to transmit an authentication request message to the handset 30. The DECT channel selection signal may be any signal that can specify the channel to be used for DECT transmission, and for example, the handset control signal may include information specifying the channel to be used for DECT transmission.

[0141] When the main unit 10 receives a correct authentication response from the handset 30, it issues a location registration acceptance command to the handset 30. This command is transmitted to the base station 20 via the base station transmission path.

[0142] A location registration acceptance command is output from the base station transmission path termination unit 21 and applied to the DECT control signal generation unit 23 as a handset control command.

[0143] The DECT control signal generator 23 outputs the location registration acceptance command itself, or a command with a reduced transmission data size obtained by removing the header, etc., as a handset control signal and applies it to the DECT transmission / reception controller 22. At the same time, the DECT control signal generator 23 also outputs a signal instructing the selection of the Cs channel or the Cf channel as a DECT channel selection signal and applies it to the DECT transmission / reception controller 22.

[0144] In response to this, the DECT transmission / reception control unit 22 transmits a location registration acceptance message to the handset 30 using the Cs channel or the Cf channel based on the DECT channel selection signal.

[0145] FIG. 14 shows an example of a call sequence from a handset.

[0146] The call sequence is used when making an outside call from the handset 30, and uses the Cs channel or Cf channel to transmit control data after establishing a one-to-one link between the base station 20 and the handset 30.

[0147] When the call processing is accepted by the main unit 10, a line lamp display command is issued to change the station line lamp (currently being used for outgoing calls) of the handset 30 from "off" to "in use." The line lamp display command may be transmitted using the Bs channel, which uses a beacon to transmit control data without establishing a link, or may be transmitted using the Cs channel or Cf channel, as with other control data.

[0148] When an unused (off) line key on the handset 30 is pressed to make a call, this information is notified to the DECT transmission / reception control unit 31 as a handset control signal, and an access request specified in the DECT MAC layer standard to establish a bearer is sent to the base station 20 whose location is registered.

[0149] When the handset 30 receives a bearer confirmation specified in the DECT MAC layer standard from the base station 20, it establishes a link in the data link layer according to the procedure specified in the DECT DATA LINK layer standard, and then transmits a call setup message to the base station 20 using the Cs channel or Cf channel.

[0150] In base station 20, the message is output as a handset control signal from DECT transmission / reception control unit 22 and applied to DECT control signal generation unit 23. DECT control signal generation unit 23 converts the received call setup message into a handset control command for main unit 10, and then transmits it over the base station transmission path to main unit 10 via base station transmission path termination unit 21. The call setup message generated on the handset 30 side may be the same as the handset control command for main unit 10, or may have unnecessary headers and the like removed in order to reduce the transmission data size.

[0151] Upon receiving the call setup command from the handset 30, the main unit 10 issues a call setup acceptance command to the handset 30. This command is transmitted to the base station 10 via the base station transmission path.

[0152] A call setup acceptance command is output from the base station transmission path termination unit 21 and applied to the DECT control signal generation unit 23 as a handset control command.

[0153] The DECT control signal generator 23 outputs the call setup acceptance command itself, or a command with a reduced transmission data size obtained by removing the header and the like, as a handset control signal and applies it to the DECT transmission / reception controller 22. At the same time, the DECT control signal generator 23 also outputs a signal instructing the selection of the Cs channel or the Cf channel as a DECT channel selection signal and applies it to the DECT transmission / reception controller 22.

[0154] The DECT transmission / reception control unit 22 transmits a call setup proceeding message to the handset 30 using the Cs channel or the Cf channel based on the DECT channel selection signal.

[0155] Main unit 10 further issues an authentication request command to handset 30 to confirm that handset 30 is a legitimate handset of its own system, and handset 30, upon receiving this, replies with an authentication response message. These commands are the same as those in the location registration sequence, so a description thereof will be omitted.

[0156] When the main unit 10 receives the call request, it issues a line lamp display command to change the line lamp (used for outgoing calls) of the handset 30 from "off" to "in use." This command is transmitted to the base station 20 via the base station transmission line.

[0157] A line lamp display command is output from the base station transmission path termination unit 21 and applied to the DECT control signal generation unit 23 as a handset control command.

[0158] The DECT control signal generator 23 outputs the line lamp display command itself, or a command with a reduced transmission data size obtained by removing the header, etc., as a handset control signal and applies it to the DECT transmission / reception controller 22. At the same time, the DECT control signal generator 23 also outputs a signal instructing the selection of the Bs channel as a DECT channel selection signal and applies it to the DECT transmission / reception controller 22.

[0159] Based on the DECT channel selection signal, the DECT transmission / reception control unit 22 uses the Bs channel to transmit a line lamp display message to the handset 30. Since the line lamp display message in the call sequence is intended only for the handset 30, the Cs channel or the Cf channel may be used, as with other control data.

[0160] The main unit 10 then issues a call command to the handset 30 to notify it that the other party is being called. The call command is sent to the handset 30 via the base station 20 using the Cs channel or the Cf channel. At the same time, an audio path to the handset 30 is established, and a ring back tone is transmitted over this audio path.

[0161] The call tone for the handset 30 is transmitted using one of the downlink audio data channels of the base station transmission path. In the base station 20, the call tone is output as a multiplexed audio codec signal from the base station transmission path termination unit 21 and applied to the DECT transmission / reception control unit 22.

[0162] The base station transmission path termination unit 21 also outputs a clock for the multiplexed audio codec and an audio codec frame pulse to the DECT transmission / reception control unit 22, and the DECT transmission / reception control unit 22 stores the ring tone addressed to the handset 30 in the B-Field of the DECT traffic bearer and transmits it.

[0163] On the handset 30 side, when the call message is received, an audio path is formed, an audio codec signal of the call tone received in the B-Field of the DECT traffic bearer is supplied to the audio codec, and the call tone is output from the speaker.

[0164] When the other party goes off-hook, this information is sent from the telephone network to the main unit 10 via the telephone line, and the main unit 10 issues a response command to notify the handset 30, and the call state is established.

[0165] FIG. 15 shows an example of a line lamp display sequence.

[0166] This sequence is a control sequence for notifying other handsets that the central office line is busy when, for example, one key telephone or handset makes an outside call.

[0167] When the main unit 10 detects that a new call has been placed and the central office line has become busy, it issues a line lamp display command to each of the other handset units to notify them that the line is in use. This command is transmitted to the base station 20 via the base station transmission line. The base station transmission line termination unit 21 outputs the line lamp display command and applies it to the DECT control signal generation unit 23 as a handset control command.

[0168] The DECT control signal generator 23 outputs the line lamp display command itself, or a command with a reduced transmission data size obtained by removing the header, etc., as a handset control signal and applies it to the DECT transmission / reception controller 22. At the same time, the DECT control signal generator 23 also outputs a signal instructing the selection of the Bs channel as a DECT channel selection signal and applies it to the DECT transmission / reception controller 22.

[0169] The DECT transmission / reception control unit 22 transmits a line lamp display message to the handset 30 using the Bs channel based on the DECT channel selection signal.

[0170] An example of a line lamp display message transmitted from a base station using such a Bs channel is shown in FIG. 16. The message may include message type information, intra-base station terminal identifier information, and line key status information. Here, the message type may include, for example, "line lamp display information for a terminal with eight station line keys." Furthermore, the intra-base station terminal identifier information may be, for example, paging group information and intra-base station terminal identifier information determined by the base station in a location registration acceptance message received by the terminal at the end of the location registration sequence. Here, the intra-base station terminal identifier information may be the same as the paging group information. It is desirable that the intra-base station terminal identifier information be different for each terminal in the base station.

[0171] Specifically, for example, if the maximum number of connected handset devices in a base station is 32, the intra-base station handset identifier information may be a natural number between 0 and 31. Furthermore, one Bs channel may be used to broadcast line lamp display messages for two or more handset devices. In this case, the two or more handset devices may belong to the same paging group and be identified by the intra-base station handset identifier information. The line key status information may include status information for multiple, for example, eight, line keys. The line key status may be 3-bit information for identifying states such as "idle," "own communication," "other communication," "other on hold," "incoming external call," and "internal call." The line key status information may broadcast status information for all, for example, eight, line keys, or may broadcast status information for only line keys whose status has changed. Furthermore, the base station may retain status information for all line keys, and periodically broadcast the line key status information even when the line key status remains unchanged.

[0172] On the handset 30 side, the DECT transmission / reception control unit 31 outputs a line lamp display message as a handset control signal, which is applied to the handset control unit 32. The line lamp display message can include information specifying the station line key to be controlled and information indicating the state of that station line key, i.e., whether it is in use by another unit. In response to this, the handset control unit 32 controls the station line key to display a busy signal, for example, to light up.

[0173] 15, a line lamp display command is issued to each of five slave units 30, but even if there are more slave units 30, a line lamp display command is issued to each of all of the slave units 30. Also, for simplicity, FIG. 15 shows a case where all of the slave units 30 are connected to the same base station, but if there are slave units connected to different base stations 30, a line lamp display command is sent to the base station 20 to which each slave unit 30 to be controlled is connected, and is transmitted to each slave unit 30 via each base station 20.

[0174] FIG. 17 shows an example of an external call incoming sequence.

[0175] Here, the control sequence is shown for when an outside call is received by handset 1, which is connected to base station 1 and has been designated to ring, and handset 2 to handset 5, which have not been designated to ring. For handset 1, not only is the incoming call lamp (blinking) displayed on the corresponding local line key, but a ring tone is sounded to notify the call. Also shown here is the operation when handset 1 answers the call and enters a call state. Note that in Figure 17, handset units designated to ring are indicated with an "*" above them.

[0176] The main unit 10 issues a call setup command to the handset 1 for which a sound has been specified to notify it of an incoming call. Furthermore, the main unit 10 also issues line lamp display commands not only to the handset 1 but also to the handset 2-5 for which a sound has not been specified, thereby notifying the incoming call by lamp display. These commands are transmitted via the base station transmission path to the base station 20 to which the handset 1-5 is connected. The base station transmission path termination unit 21 of the base station 20 outputs the call setup command and the line lamp display commands for each of the handset 1-5, and applies them to the DECT control signal generation unit 23 as handset control commands.

[0177] The DECT control signal generator 23 generates an incoming call message based on the information of the called handset ID included in the call setup command, and applies it as a handset control signal to the DECT transmission / reception controller 22. At the same time, the DECT control signal generator 23 also outputs a signal instructing the selection of the Bs channel as a DECT channel selection signal, which is applied to the DECT transmission / reception controller 22. The DECT transmission / reception controller 22 transmits the incoming call message to the handset 1 using the Bs channel based on the DECT channel selection signal.

[0178] The DECT control signal generation unit 23 further outputs the line lamp display command itself for each of the handset units 1 to 5, or a command with a reduced transmission data size excluding headers and the like, as a handset control signal, and applies it to the DECT transmission / reception control unit 22. At the same time, the DECT control signal generation unit 23 also outputs a signal instructing the selection of the Bs channel as a DECT channel selection signal for each handset control signal, and applies it to the DECT transmission / reception control unit 22.

[0179] The DECT transmission / reception control section 22 transmits a line lamp display message for each of the handsets 1 to 5 to the handsets 1 to 5 using the Bs channel based on the DECT channel selection signal.

[0180] Next, when the handset 1 receives the incoming call message, a one-to-one link is established between the base station 10 and the handset 1, and control data transmission is performed using the Cs channel or Cf channel. Specifically, the handset 1 first transmits an access request defined in the DECT MAC layer standard to the connected base station 10 in order to establish a bearer. Then, upon receiving a bearer confirmation defined in the DECT MAC layer standard from the base station 10, the handset 1 establishes a link in the data link layer according to the procedure defined in the DECT DATA LINK layer standard.

[0181] The DECT control signal generator 23 also outputs the call setup command itself, or the call setup command with the called handset ID information removed, or the call setup command with the header and other information removed to reduce the transmission data size, as a handset control signal and applies it to the DECT transmission / reception controller 22. At the same time, the DECT control signal generator 23 also outputs a signal instructing the selection of the Cs channel or the Cf channel as a DECT channel selection signal, which is applied to the DECT transmission / reception controller 22, and after a link is established in the data link layer, the call setup message is transmitted using the Cs channel or the Cf channel.

[0182] When the handset 1 receives the call setup message, it generates a call setup acceptance message and transmits it to the main unit 10 using the Cs channel or the Cf channel. The authentication request and authentication response may conform to the DECT NETWORK layer standard (ETSI EN 300-175-5) or may be based on any authentication procedure using an authentication key.

[0183] Main unit 10 further issues an authentication request command to handset 1 to verify that handset 1 is a legitimate handset of its own system, and upon receiving this, handset 1 replies with an authentication response message. These commands are the same as those in the location registration sequence, so a description thereof will be omitted.

[0184] When main unit 10 receives the authentication response command from handset 1, it determines that the central office line is in use, and issues a line lamp display command to each of handset units 1 to 5 to notify this state of the central office line. A line lamp display command is issued to handset unit 1 to display that the central office line is in use by itself, for example, to instruct the central office line to flash green, and a line lamp display command is issued to handset units 2 to 5 to display that the central office line is in use by another device, for example, to instruct the central office line to light red.

[0185] These commands are transmitted via the base station transmission path to base station 20 to which handset units 1 to 5 are connected. Line lamp display commands for each of handset units 1 to 5 are output from base station transmission path termination unit 21 of base station 20, and applied to DECT control signal generation unit 23 as handset control commands.

[0186] The DECT control signal generator 23 generates a line lamp display message based on the line lamp display information included in each line lamp display command, and applies this as a handset control signal to the DECT transmission / reception controller 22. At the same time, the DECT control signal generator 23 also outputs a signal instructing the selection of the Bs channel as a DECT channel selection signal, which is applied to the DECT transmission / reception controller 22.

[0187] The DECT transmission / reception control section 22 transmits a line lamp display message to each of the handset units 1 to 5 using the Bs channel based on the DECT channel selection signal.

[0188] After transmitting the authentication response message, handset 1 uses the ringer to ring for the incoming call, and then transmits a call message to base station 20 using the Cs channel or Cf channel to notify main unit 10 that the ring for the incoming call has started. The call message is converted into a call command in DECT control signal generator 23 and notified to main unit 10.

[0189] When the handset 1 responds by pressing a line key after transmitting the call message, a response message is generated and transmitted to the base station 20 using the Cs or Cf channel. The response message is converted into a response command by the DECT control signal generator 23 and notified to the main unit 10.

[0190] When the main unit 10 receives the response command from the handset 1, it issues a response confirmation command and enters a call state. When the handset 1 receives the response confirmation message from the base station 10, it enters a call state.

[0191] As explained above, in the present invention, when an outside call is received, the incoming call information and incoming office line lamp information are transmitted to all handset units assigned to that office line without establishing a link, so that all handset units can be notified of the incoming call without being limited by the maximum number of simultaneous calls.

[0192] FIG. 18 shows an example of a sequence in the case of a handover. If communication quality deteriorates while handset 1 is performing two-way communication with base station 1, and a new base station 2 with better wireless communication capabilities is discovered as a result of searching for a base station in communication, handset 1 establishes a link with the new adjacent base station 2, transitions to a handover state, and then disconnects the old link and transitions to a communication locked state with the adjacent base station 2. In other words, if handset 1 moves and needs to reconnect to an adjacent base station 2 with better wireless communication capabilities, even during a call, handset 1 will reconnect to the adjacent base station 2 with better wireless communication capabilities and enter its call area.

[0193] FIG. 19 shows an example of a keep-alive sequence from a child device. Since a handset may move out of service area or may be turned off, the handset transmits a keep-alive signal at a regular interval (T1), for example, every 30 seconds, to the connected base station to notify that the handset is in service and ready to make and receive calls. The base station monitors the keep-alive signal from the handset, and if it does not receive a keep-alive signal for a predetermined period of time, for example, three minutes, it determines that the handset is outside the communication area of ​​the base station, deletes the handset's location registration, decrements the number of handset units connected to the base station by one, and notifies the main unit that the handset is out of service area.

[0194] Further, a technique for notifying all handset units of incoming call information within one to two seconds will be described below.

[0195] The base station 20 in Figures 5 and 7 is equipped with a base station status management unit 24, which manages the number of terminals connected to the base station 20 and the number of terminals connected to the base station that are performing call connections.

[0196] As shown in FIG. 32, a short page paging frame Pt ​​can broadcast 12 bits of MAC information, and when the type of MAC information to be transmitted is set to "4b'1010", base station status information can be broadcast. Note that when broadcasting MAC information using a short page paging frame Pt, 4 bits of base station status information can be broadcast. Specifically, by setting the base station status information to "XXX1" (X is 0 or 1), it can be broadcast that the number of communicating terminal devices has reached the upper limit, and by setting the base station status information to "XX1X" (X is 0 or 1), it can be broadcast that the number of connected terminal devices has reached the upper limit.

[0197] The base station status management unit 24 applies information on the number of terminals connected to the base station 20 or information on whether the number of terminals connected to the base station has reached a predetermined upper limit, and information on the number of terminals connected to the base station 20 that are performing call connections or information on whether the number of terminals performing call connections has reached a predetermined upper limit, as a base station status report signal to the DECT transmission / reception control unit 22. The report by the base station status report signal may be made when the base station status changes, or may be made at predetermined time intervals, for example, every 5 seconds.

[0198] When the DECT transmission / reception control unit 22 receives a base station status notification signal from the base station status management unit 24, it uses the MAC information notification of the short page frame to notify the base station 20 of the number of connected terminals or whether the number of connected terminals has reached an upper limit, and the number of call-connected terminals or whether the number of call-connected terminals connected to the base station 20 has reached an upper limit.

[0199] A mobile device 30 that has registered its location with any base station 20 enters an idle-lock state and intermittently receives paging frames Pt at 160 ms or 640 ms intervals. At this time, the mobile device 30 receives the paging frame Pt ​​transmitted in the first frame 0 of each multiframe. When multiple paging frames Pt are transmitted within one multiframe, the first bit of the paging header notifies the mobile device 30 whether there is a subsequent paging frame Pt. If it is notified that there is no subsequent paging frame Pt, the mobile device 30 transitions to a sleep state for approximately 160 ms or 640 ms after receiving the paging frame Pt.

[0200] If notified that there is a subsequent paging frame Pt, the handset 30 operates to receive the subsequent paging frame Pt ​​after receiving the paging frame Pt, and continues receiving the paging frame Pt ​​until notified that there is no subsequent paging frame Pt.

[0201] When the DECT transmission / reception control unit 22 receives the base station status notification signal, it adds a short page frame for reporting this in the base station status information to another paging frame Pt ​​and reports it, and the handset 30 that receives this performs a control sequence taking this into consideration. For example, a handset 30 that attempts to make a call to a base station 20 where the number of connected handset 30 has reached the upper limit, or a handset 30 that has received a call, first performs roaming processing and then performs the operation of making or receiving a call with the new base station 20.

[0202] Furthermore, when registering the location of the handset 30 after powering on or searching for a base station during roaming, the base station 20 with the highest beacon reception level may be selected after excluding base stations 20 for which the number of connected handset units has reached the upper limit. The upper limit on the number of call-connected handset units may be the number of voice channels in the base station transmission path. It is also desirable to limit the number of connected handset units to the number that can transmit incoming call information within 1 to 2 seconds.

[0203] The DECT standard specifies that the maximum discontinuous reception period is 640 ms, and that frame 0 in one multiframe is discontinuously received. As already explained, one multiframe can transmit up to six Pt frames, i.e., lamp information or incoming call information.

[0204] In the DECT base station 20, unused channels that are not used for communication are used to constantly detect available channels, and depending on the results of this, the transmission frequency or transmission slot of the beacon may be changed over time.

[0205] A change in the transmission frequency or transmission slot of the beacon at each base station 20 is notified to all mobile devices 30 connected to that base station using MAC information broadcast in the short page frame. Note that a mobile device 30 that receives intermittently at a cycle of 640 ms receives a paging frame Pt ​​of frame 0 once every four multiframes, but a DECT base station 20 generally does not know which multiframes are received by a mobile device 30 that receives intermittently, and transmits the same paging frame Pt ​​four times in four consecutive multiframes, thereby enabling all mobile devices 30 to receive the information in that paging frame Pt.

[0206] On the other hand, from the viewpoint of accommodating as many handset devices as possible in one base station and notifying all of these handset devices of incoming call information as quickly as possible, it is desirable to notify incoming call information for different handset devices in each of the four multi-frames transmitted within a 640 ms cycle.

[0207] For this reason, the base station 20 is configured to notify each handset 30 of the multi-frames that the handset 30 should receive intermittently from among the four multi-frames transmitted at 640 ms intervals when the handset 30 registers its location with the base station 20. Furthermore, each handset 30 connected to the base station 20 operates to intermittently receive the multi-frames designated at the time of location registration from among the four multi-frames transmitted at 640 ms intervals.

[0208] FIG. 20 shows an example of a paging frame transmission operation in the case of four paging groups.

[0209] Here, of the four multi-frames transmitted within a 640 ms cycle, there are four paging groups: paging group 1, which receives the first multi-frame; paging group 2, which receives the second multi-frame; paging group 3, which receives the third multi-frame; and paging group 4, which receives the last multi-frame. The base station assigns one of the paging groups to each handset.

[0210] Lamp information and incoming call information for the handsets belonging to paging group 1 are transmitted in the first of four multiframes transmitted at 640 ms intervals, and the handsets belonging to paging group 1 receive this information intermittently at this timing. For handsets belonging to paging groups 2, 3, and 4, lamp information and incoming call information are transmitted in the second, third, and fourth multiframes, respectively, and the handsets belonging to each paging group receive this information intermittently at this timing.

[0211] The paging group assignment method may be any method that allows the base station and the handset to share the paging group assignment results. For example, the paging group may be determined by the base station and notified to the handset in a location registration acceptance message in the location registration sequence. Alternatively, the paging group may be uniquely determined based on system-specific identification information, such as the handset ID, assigned when the handset is registered with the cordless telephone device. Specifically, the paging group may be determined based on the remainder of the handset ID modulo 4. Information that needs to be notified to all handset devices connected to the base station, such as MAC information, may be transmitted a total of four times in each of the four multiframes transmitted at a 640 ms cycle.

[0212] FIG. 21 shows another example of the paging frame transmission operation in the case of four paging groups.

[0213] Here, the transmission operation of the paging frame Pt ​​is shown in the case where four paging groups each have two mobile terminals, for a total of eight mobile terminals connected. For example, in a multi-frame assigned to paging group 1, lamp information or incoming call information for handset 1 and handset 2 is transmitted in two paging frames Pt, and handset 1 and handset 2 first intermittently receive the paging frame Pt ​​transmitted in frame 0.

[0214] At this time, the first bit of the Pt header is 1, indicating that there is another paging frame Pt ​​in the same multiframe, and frame 2 is also intermittently received. The first bit of this Pt header is 0, and handset 1 and handset 2 operate in sleep mode until the next intermittent reception timing, approximately 640 ms later.

[0215] FIG. 22 shows one form of station layout design for cordless telephone devices.

[0216] In this example, an office has three lines assigned to it. Employees in the office can make an outside call using any one of the lines. If all three lines are in use, they cannot make an outside call until one of the lines is deactivated.

[0217] In this example, four base stations are installed in the office, and the entire office is covered by the coverage areas of these four base stations. Each handset is connected to one of the base stations, and in this example, 20 handset units are connected to each base station. It is possible that a concentration of handset units may connect to a specific base station, but to ensure that station line key status information and incoming call information are notified within 640 ms, the upper limit for the number of connected handset units is set to 32, and a base station that has reached this number of connected handset units will notify this fact via a beacon, thereby preventing more than 32 handset units from connecting to a specific base station.

[0218] The line's usage status can be checked by checking the light on the line key on the handset. If the light on the line key is off, the line is free and can be used. If the light on the line key is lit, the line is in use (a call is in progress) and cannot be used. On the other hand, if an outside call comes into the office, all employees' handsets will be notified of the call within one second and their line keys will flash. Furthermore, handsets that are designated to ring will not only display the light on the line key but will also ring when the call arrives.

[0219] When an outside call comes in, the main unit issues a line lamp display command to all handsets that have that line assigned to their line key, indicating the incoming call. It also issues a call setup command to all handsets that have been designated to ring on that line. This causes the line keys of all handsets assigned to that line to flash to indicate the incoming call, and only the handsets designated to ring will ring, achieving the same functionality as a key telephone.

[0220] As described above, the handset registers its location in advance via one of the base stations, and the control unit of the main unit manages information about the base station with which each handset has registered its location, and transmits a line lamp display command and a call setup command indicating an incoming call addressed to each handset to the base station with which the handset has registered its location over the base station transmission path.

[0221] Although the embodiments have been described above, the present invention is not limited to the above-described embodiments. For example, when an external call is received, it is necessary to notify all of the terminals that are the intended recipients of the call. If it takes too long to notify the call, the caller may assume that there is no response and disconnect the call. Therefore, the time required to notify all of the terminals of the call should be as short as possible, preferably within 1 to 2 seconds.

[0222] When multiple handset units are concentrated at a specific base station and their locations are registered, incoming calls are notified to many of them via that base station. However, handset units are normally battery-powered and perform intermittent reception at relatively long intervals, for example, 640 ms, to reduce power consumption, so it takes time to notify many handset units of incoming calls and deliver line lamp information.

[0223] For this reason, an upper limit can be set for the number of location registration slaves per base station, and if this limit is exceeded, location registration can be rejected or a beacon can be used to notify that location registration is not possible, and any slaves beyond this limit can be made to register their locations with other surrounding base stations. Specifically, the intra-base station slave status management section of each base station manages the number of location registration slaves, and if this reaches the upper limit, the base station can reject any further location registration requests. [Explanation of symbols]

[0224] 10...Main device 11...Station line I / F section 12 Internal line I / F section 13. Clock generation unit 14 Circuit Switching Unit 15 Control section 20...Base station 21 Base station transmission line termination 22 DECT transmission / reception control unit 23 DECT control signal generator 24 Base station status management unit 25 Paging group number storage section for each handset 30... Handset 31 DECT transmission / reception control unit 32 Child unit control section 33. Audio Codec 34 Local line key 35. Linga 36...LCD display section 37. Mike 38···Speaker 39. Numeric keypad 40 Paging group number storage section

Claims

1. A base station for a cordless telephone device is configured by selectively using one base station and one handset among one or more base stations connected to a telephone control device connected to a wide area network and a plurality of handset units connected to the base station by wireless communication, a DECT control signal generating means for extracting information that needs to be transmitted to the handset from a handset control command transmitted from the telephone control device, to generate a handset control signal, and for selecting an optimum transmission channel for wirelessly transmitting the handset control signal in the DECT system according to the type of the handset control command; A base station for a cordless telephone device, comprising: a DECT transmission / reception control means for performing DECT radio transmission / reception and DECT TDMA / TDD frame synthesis / decomposition, and transmitting the handset control signal provided by the DECT control signal generation means using the optimum transmission channel selected by the DECT control signal generation means.

2. when the handset control command transmitted from the telephone control device is a line lamp display command, the DECT control signal generation means selects a broadcast channel as an optimum transmission channel for wirelessly transmitting the handset control signal generated from the handset control command in the DECT system; 2. The base station for a cordless telephone device according to claim 1, wherein said DECT transmission / reception control means transmits said handset control signal using said broadcast channel without establishing a link.

3. A base station for a cordless telephone device as described in claim 1, characterized in that it is equipped with a base station status management means for generating, as base station status information, information on the number of calling handsets and the number of connected handsets, and 2-bit information on whether the number of calling handsets and the number of connected handsets have reached their respective upper limits, and further for generating a base station status notification signal that instructs the base station status information to be notified in the MAC information of a beacon, and the base station status notification signal is notified via the DECT transmission / reception control means.

4. A cordless telephone device is configured by selectively using one base station and one handset among one or more base stations connected to a telephone control device of a digital cordless telephone system connected to a wide area network and a plurality of handset units connected to the base stations by wireless communication, the cordless telephone device comprising: The base station a DECT control signal generating means for extracting information that needs to be transmitted to the handset from a handset control command transmitted from the telephone control device, to generate a handset control signal, and for selecting an optimum transmission channel for wirelessly transmitting the handset control signal in the DECT system according to the type of the handset control command; a DECT transmission / reception control means for performing DECT radio transmission / reception and DECT TDMA / TDD frame synthesis / decomposition, and transmitting the handset control signal provided by the DECT control signal generation means using the optimum transmission channel selected by the DECT control signal generation means; A paging group number storage means for each handset is provided, transmitting the handset control signal to the handset only on a Bs channel of a multiframe corresponding to a paging group number of the handset; The slave unit is A paging group number storage unit is provided, A cordless telephone device characterized in that, during intermittent reception at a cycle of 640 ms, reception is performed only in multiframes corresponding to the paging group numbers stored in said paging group number storage section.

5. when the handset control command transmitted from the telephone control device is a line lamp display command, the DECT control signal generation means selects a broadcast channel as an optimum transmission channel for wirelessly transmitting the handset control signal generated from the handset control command in the DECT system; 5. The cordless telephone device according to claim 4, wherein the DECT transmission / reception control means transmits the handset control signal using the broadcast channel without establishing a link.

6. The cordless telephone device according to claim 4 or 5, characterized in that the paging group number of the handset is determined by the base station in consideration of load balancing during the location registration sequence with the base station, and this number is notified to the handset.

7. A cordless telephone device as described in claim 4 or 5, characterized in that the paging group number of the handset is determined by the base station side and the handset side, respectively, based on system-specific handset identification information assigned when the handset is included in the digital cordless telephone system.

8. The base station a base station status management means for generating, as base station status information, information on the number of handset terminals and the number of connected handset terminals of the base station, and two-bit information on whether the number of handset terminals and the number of connected handset terminals have reached their respective upper limits, and further for generating a base station status report signal for instructing that the base station status information be reported in MAC information of a beacon; The slave unit is A cordless telephone device as described in any one of claims 4 to 7, characterized in that it is provided with a handset control unit that operates to select a base station to connect to from among base stations for which the number of handsets in communication has not reached the upper limit in the base station status information reported by the beacon in a base station search immediately before link establishment, and to select a base station to connect to from among base stations for which the number of handsets connected has not reached the upper limit in the base station status information reported by the beacon in other base station searches.

Images