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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a communication apparatus and,
more particularly, is directed to a radio communication apparatus suitably
to be applied to a cordless telephone connected to a digital line network
such as an ISDN (an Integrated Services Digital Network) and so on.
2. Description of the Related Art
Recently, there have been utilized various types of cordless telephones
which are movable freely and able to perform a communication within a
predetermined service area, e.g., a radius of about 100 m. The cordless
telephone is constituted by a master station directly connected to a
telephone line network and a remote station carried by a user so that a
radio communication is performed between the master station and the remote
station. Some types of the cordless telephones can provide a plurality of
remote stations which are able to communicate with a single master
station.
FIG. 1 shows an arrangement of an example of conventional cordless
telephones connected to a general telephone line network. In this example,
three remote stations 7 to 9 are utilized and a telephone line network
interface 3 of a master station 2 is connected to an end terminal of an
analog telephone line network 1. The master station 2 further includes a
radio transceiver 4 connected to the telephone line network interface 3
and a controller 5 for controlling the processings of the interface 3 and
the radio transceiver 4.
Namely, under the control of the controller 5, a signal transmitted from a
central telephone exchange or office side through the telephone line
network 1 is received by the telephone line network interface 3 and then
modulated by the radio transceiver 4 to obtain a modulated signal of a
predetermined channel for radio transmission. The modulated signal is
transmitted as a radio signal through an antenna 6 to the first to third
remote stations 7 to 9. Each of the first to third remote stations 7 to 9
is provided with a speaker and a microphone for a speech and a dial
keypad, etc. The remote stations 7, 8 and 9 receive the radio signal
transmitted from the master station 2 by antennas 7a, 8a and 9a connected
thereto, respectively, and each remote station has a circuit configuration
for discriminating whether or not the radio signal designates itself on
the basis of a control signal contained in the radio signal. If the remote
station discriminates that the radio signal designates itself, the remote
station performs a receiving processing of the radio signal to reproduce a
voice signal from its speaker.
Each of the remote stations 7, 8 and 9 detects a voice signal by its
microphone and modulates the detected voice signal by a circuit
configuration provided therein to obtain a modulated signal for a radio
transmission, thereby transmitting the modulated signal from its antennas
7a, 8a or 9a. In the master station 2, the modulated signal transmitted
from the remote station is received by the radio transceiver 4 through the
antenna 6 and then transmitted to the telephone line network 1 through the
telephone line network interface 3. In this manner, a so-called line wire
speech can be performed by any of the remote stations 7, 8 and 9 through
the master station 2.
Further, each of the remote stations 7 to 9 can transmit a radio signal to
the master station with the designation of another remote station, thereby
enabling a speech among the respective remote stations, that is, an
extension speech.
As one of telephone line networks, a digital line network called ISDN has
been started to be serviced. By utilizing the ISDN, various kinds of data
can be transmitted effectively and further various controls such as the
designation of a terminal receiving an incoming signal or the like can be
performed. That is, a desired one of plural terminals commonly connected
to one line at the respective subscriber sides can be called by
designating the desired terminal through the use of a subaddress or a
direct dial-in number (DDI number), etc.
However, in case of connecting a telephone provided in a home to the ISDN,
an ISDN telephone is required. That is, in case of connecting the
above-described cordless telephone to the ISDN, for example, the telephone
line network interface 3 is required to be replaced by the ISDN interface,
whereby a speech can be performed through the ISDN at least in each of the
remote stations 7 to 9.
However, in case of the cordless telephone, even if the telephone line
network interface 3 is replaced by the ISDN interface, there can not get
services such as the above-described designation of a terminal capable in
the ISDN. That is, unless each of the remote stations 7 to 9 is provided
with a circuit for discriminating a subaddress or the DDI number of the
ISDN etc., it can not get services such as the designation of a terminal
but merely can perform a speech similar to that capable through the use of
the normal analog telephone line network, so that the ISDN can not be
utilized effectively.
If each of the remote stations is implemented with the ISDN call sequence,
the constructions of the remote station become more complicated, then the
constructions of a system of the cordless telephone become larger
disadvantageously. Further, the similar problem is found when, to the
ISDN, there is connected a telephone in which a plurality of remote
stations are connected to a master station through signal lines other than
the cordless telephone.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved radio
communication apparatus for an ISDN in which the aforementioned
shortcomings and disadvantages encountered with the prior art can be
eliminated.
More specifically, it is an object of the present invention to provide a
radio communication apparatus for an ISDN having a plurality of remote
stations such as a cordless telephone which can get services of the
digital line network such as the ISDN with simple circuit configurations.
As an aspect of the present invention, a radio communication apparatus
including a main telephone connected to a digital line network and a
plurality of sub telephones each being capable of performing a radio
communication to the main telephone, the main telephone is comprised of a
memory for storing a subaddress and a direct dial-in number of each of the
plurality of sub telephones, and a unit for, upon receiving an incoming
signal transmitted from the digital line network, detecting a subaddress
or a direct dial-in number included in the incoming signal, discriminating
a sub telephone associated with the detected subaddress or direct dial-in
number in accordance with the data stored in the memory, and transmitting
the incoming signal to the discriminated sub telephone.
According to the radio communication apparatus for an ISDN of the present
invention, when, to a digital line network such as the ISDN, there is
connected a radio communication apparatus such as a cordless telephone
wherein a radio communication is performed between a main telephone and
sub telephones, the sub telephones can be controlled at the main telephone
side in accordance with a subaddress or a DDI number included in an
incoming signal. Accordingly, the radio communication apparatus can obtain
services such as the selection of a terminal receiving an incoming signal
without detecting a subaddress or a DDI number of the incoming signal at
each of the sub telephones, so that the constructions of each of the sub
telephones can be simplified.
The preceding and other objects, features, and advantages of the present
invention will become apparent from the following detailed description of
illustrative embodiment thereof when read in conjunction with the
accompanying drawings, in which like reference numerals are used to
identify the same or similar parts in the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows in block form an arrangement of an example of conventional
cordless telephones;
FIG. 2 shows in block form an arrangement of an embodiment of a master
station of a cordless telephone according to the present invention;
FIG. 3 shows a schematic diagram of an example of data stored in the data
memory used in the above embodiment;
FIG. 4 shows in block form an arrangement of the embodiment of the system
of the cordless telephone;
FIG. 5 is a flowchart to which references will be made in explaining
operation of the master station shown in FIG. 2; and
FIG. 6 is a flowchart to which references will be made in explaining
discrimination operation of an attribute in the master station in FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of a radio communication apparatus for an ISDN according to
the present invention will now be described with reference to FIGS. 2 to
6, in which case the present invention is applied to a cordless telephone
connected to the ISDN.
FIG. 2 shows an arrangement of a master station 10 of the embodiment of a
cordless telephone, in which the master station 10 is connected to an ISDN
line network i. Namely, an end terminal of the ISDN line network i is
connected to an ISDN interface 11 of the master station 10 of the cordless
telephone. The ISDN interface 11 receives an incoming signal transmitted
from a central telephone exchange side through the line network i and
supplies the incoming signal to circuit arrangements within the master
station 10 necessary for processing the incoming signal. Further, the ISDN
interface 11 converts an outgoing signal supplied from a circuit
arrangement within the master station 10 into an outgoing signal for the
ISDN and thereby transmits it to the ISDN line network i. In this case, a
controller 12 of the master station 10 is connected to the ISDN interface
11 and under the control of the controller 12, the incoming and outgoing
signals are processed. At that time, when an audio signal is converted
into digital data and then transmitted from the master station 10 to the
ISDN line network i, the ISDN interface 11 converts the digital data into
an analog audio signal. While, when an analog audio signal is supplied to
the ISDN line network i from the master station 10, the ISDN interface 11
converts the same into digital data to form an outgoing signal.
In the master station 10, a transmitter 13 is supplied with a signal to be
transmitted to a remote station, which will be described later, from the
controller 12 and modulates it by a signal of a predetermined frequency
supplied from a frequency synthesizer 14 to generate a modulated signal
with a predetermined frequency (a predetermined transmission channel),
thereby transmitting the modulated frequency signal through an antenna 15
to a predetermined remote station as a radio frequency signal. The antenna
15, on the other hand, receives a radio frequency signal transmitted from
a remote station and supplies it to a receiver 16. The receiver 16
demodulates the radio frequency signal of the predetermined transmission
channel in accordance with the signal with a predetermined frequency
supplied from the frequency synthesizer 14.
To the controller 12, there are connected a speaker 18, a microphone 19 and
a dial keypad 20 through a man-machine interface 17. The speaker 18 and
microphone 19 constitute a handset, and the transmission operation and so
on can be performed by the dial keypad 20 so that a speech utilizing the
ISDN line network i can be performed only by the master station 10.
To the controller 12, there is also connected a dial memory 21 and a data
memory 22. The dial memory 21 stores data of abbreviated dial numbers
which are used upon transmitting by the operation of the dial keypad 20
etc. The data memory 22 stores data related to the respective remote
stations such as direct dial-in numbers, subaddresses and attribute data
or the like set to the respective remote stations. These respective data
are required for performing various services capable by the ISDN as
explained below.
The DDI (direct dial-in) numbers are dedicated dial numbers set for the
respective remote stations which are provided separately from dial numbers
set for respective users, so that, by performing the transmitting
operation by using the DDI number, only one remote station designated
thereby can be called. The subaddresses are peculiar numbers set for the
respective remote stations, so that, upon transmitting, by inputting the
subaddress subsequent to the dial number set for the user, only the remote
station designated thereby can be called. The attribute data are data
representing attributes of the respective remote stations or devices
connected thereto. For example, the attribute data represents kinds of the
remote stations such as a remote station capable of a normal speech, that
capable of a speech of a high-quality audio signal, that connected to a
facsimile device, that connected to a videotex terminal or that connected
to a telex terminal. The attribute data further includes various data
related to lower layer and higher layer matchings or the like which are
stored in the memory 22.
These data are stored in the data memory 22 in a manner as shown in FIG. 3.
Referring to FIG. 3, terminal identifiers (IDs) are allocated to the
master station and the remote stations of the cordless telephone of this
embodiment, respectively, and storage areas are provided for each of the
terminal IDs for storing the subaddresses, DDI numbers and attribute data.
In this example, the DDI numbers are set only for terminals registered at
the central telephone exchange side.
When a DDI number, a subaddress and attribute data etc. are set for the
master station, these data are also stored in the data memory 22. Further,
when there are other data required for performing various services capable
by the ISDN, these data are also stored in the data memory 22.
FIG. 4 shows an arrangement of the total system of the cordless telephone
of this embodiment, wherein five remote stations 31 to 35 are provided for
one master station 10 so that a radio communication is performed between
the antenna 15 of the master station 10 and each of antennas 41 to 45 of
the remote stations 31 to 35. In this example, each of the first and
second remote stations 31 and 32 serves as a telephone capable of a speech
using a normal voice and has a speaker and a microphone constituting a
handset and a dial keypad. The third remote station 33 is connected with a
facsimile terminal 51 so that the reception and transmission of a document
is possible. The fourth remote station 34 is connected with a telex
terminal 52 so that the transmission and reception of character data or
the like are possible. Further, the fifth remote terminal 35 is connected
with a videotex terminal 53 so that the transmission and reception of
picture data and so on are possible. The data related to signals dealt
with by these remote stations are previously stored in the data memory 22.
When one of the remote stations 31 and 32 is a telephone capable of a
speech of high-quality voice, of which data is also stored in the data
memory 22.
Operation of the thus constituted cordless telephone will be described in a
case where an incoming signal is transmitted thereto through the ISDN line
network i. An ISDN incoming signal includes various kinds of call setup
messages. These call setup messages are discriminated by the ISDN
interface 11 and the results of the discrimination are supplied to the
controller 12. The discrimination operation will be explained with
reference to a flowchart forming FIG. 5.
Referring to FIG. 5, following the Start of operation, a protocol
identifier of the incoming signal is checked by the ISDN interface 11 in
step 101. If the protocol identifier is discriminated correctly as
represented by a YES at decision step 101, then the controller 12 judges
whether or not the messages include a DDI number (incoming number) in step
102. If the messages include a DDI number as represented by a YES at step
102, then the processing proceeds to the next decision step 103.
In step 103, the controller 12 judges whether or not there is a remote
station (terminal device) to which the DDI number designated by the
messages is set in accordance with the data stored in the data memory 22.
If there is a remote station (that is, one of the first to fifth remote
stations 31 to 35) corresponding to the DDI number as represented by a YES
at decision step 103, then the controller 12 judges whether or not the
messages designate a subaddress in step 104. If the messages designate a
subaddress as represented by a YES at step 104, then the processing
proceeds to the next decision step 105.
In step 105, the controller 12 detects a remote station (terminal device)
to which the subaddress designated by the messages is set in accordance
with the data stored in the data memory 22 and further Judges whether or
not the detected remote station is same as that designated by the DDI
number.
If the detected remote station is the same as that designated by the DDI
number as represented by a YES at decision step 105, then the processing
proceeds to the next step 106.
In step 106, the controller 12 determines that the incoming signal is to be
transmitted to the remote station designated by the DDI number and the
subaddress, thereby transmitting a call accept request to the designated
remote station as a radio wave when an attribute designated by the
messages coincides with that of the designated remote station as described
below. If the receiving operation is performed at the designated remote
station in response to the call accept request, the controller 12
transmits an incoming signal subjected to a predetermined processing to
the designated remote station, thereby executing a receiving procedure of
the incoming signal at the remote station.
If the messages do not designate a subaddress as represented by a NO at
step 104, then the processing also proceeds to step 106. In step 106, the
controller 12 transmits a call accept request to the remote station
designated by the DDI number as a radio wave when an attribute designated
by the messages coincides with that of the designated remote station as
described below. If the receiving operation is performed at the designated
remote station in response to the call accept request, the controller 12
transmits an incoming signal subjected to the predetermined processing to
the designated remote station, thereby executing a receiving procedure of
the incoming signal at the designated remote station.
If the messages do not include a DDI number as represented by a NO at step
102, then the processing proceeds to step 107, whereat the controller 12
determines whether or not the messages designate a subaddress. If the
messages designate a subaddress as represented by a YES at step 107, then
the controller 12 determines whether or not there is a remote station
(terminal device) to which the subaddress designated by the messages is
set in accordance with the data stored in the data memory 22 in step 108.
If there is a remote station to which the subaddress designated by the
message is set as represented by a YES at decision step 108, then the
processing proceeds to the next step 106.
In step 106, the controller 12 transmits a call accept request to the
remote station designated by the subaddress as a radio wave when an
attribute designated by the messages coincides with that of the designated
remote station as described below. If the receiving operation is performed
at the designated remote station in response to the call accept request,
the controller 12 transmits an incoming signal subjected to the
predetermined processing to the designated remote station, thereby
executing a receiving procedure of the incoming signal at the designated
remote station.
Further, if the protocol identifier is not discriminated correctly as
represented by a NO at decision step 101, if there is not a remote station
corresponding to the DDI number as represented by a NO at decision step
103, if the detected remote station is not same as that designated by the
DDI number as represented by a NO at decision step 105, or if there is not
a remote station to which the subaddress designated by the message is set
as represented by a NO at decision step 108, then the processing proceeds
to the next step 109.
In step 109, all messages relating to the DDI number and the subaddress
used for the judgements in steps 101, 103, 105 and 108 are ignored.
After the messages have been processed with respect to the DDI number and
the subaddress, when the remote station designated by the DDI number
and/or the subaddress is detected and the processing proceeds to step 106
as described above, the controller 12 determines whether or not the
attribute designated by the messages coincides with that of the designated
remote station. Only when the attribute designated by the messages
coincides with that of the designated remote station, the receiving
operation of an incoming signal is performed at the designated remote
station.
Operation of the controller 12 with respect to the attributes will be
described with reference to a flowchart forming FIG. 6.
Referring to FIG. 6, following the Start of operation, the processing
proceeds to decision step 201. In step 201, the controller 12
discriminates an attribute from the messages of the incoming signal, and
determines whether or not the attribute designated by the messages
coincides with that of the remote station designated by the DDI number
and/or the subaddress of the messages. For example, the controller 12
determines whether or not the transmission ability of the designated
remote station coincides with the incoming signal, or whether or not the
attribute of layer matching such as the lower layer matching and the
higher layer matching coincides with that of the incoming signal.
If the attribute designated by the messages coincides with that of the
designated remote station as represented by a YES at decision step 201,
then the controller 12 processes the attribute relating to the designated
remote station or terminal in the next step 202.
If the attribute designated by the messages does not coincide with that of
the designated remote station as represented by a NO at decision step 201,
then the controller 12 ignores all messages relating to the attribute in
step 203.
Now, even when all messages relating to the DDI number and the subaddress
are ignored in step 109, the controller 12 discriminates an attribute of
the messages of the incoming signal similarly, and determines whether or
not there is a remote station whose attribute coincides with the attribute
designated by the messages. In this case, if there is a remote station
whose attribute coincides with the attribute designated by the messages,
the controller 12 performs the processing with respect to this remote
station.
That is, the controller 12 transmits a call accept request to the remote
station whose attribute coincides with that designated by the messages.
Then, when the receiving operation is performed at the remote station in
response to the call accept request, the controller 12 transmits an
incoming signal subjected to the predetermined processing to the remote
station, thereby executing a receiving procedure of the incoming signal at
the remote station. For example, when the messages of the incoming signal
do not designate any one of the DDI number and the subaddress but
designates only an attribute representing a facsimile signal, for example,
the controller 12 transmits the incoming signal to only the third remote
station 33 to which the facsimile terminal 51 is connected.
As describe above, according to the cordless telephone of this embodiment,
although the ISDN interface 11 is provided only for the master station 10,
various services capable by the ISDN can be performed at each of the
remote stations 31 to 35. That is, if an incoming signal includes messages
relating to a DDI number and a subaddress or messages relating to an
attribute, the master station 10 performs the processings relating to the
messages in accordance with data stored in the data memory 22 provided in
the master station 10. Then, each of the remote stations can perform the
processings relating to the messages without discriminating the messages,
so that the arrangement of a cordless telephone connected to the ISDN line
network can be simplified. In this case, since only one ISDN interface 11
may be provided in the master station 10 regardless of the number of the
remote stations, the arrangement of the cordless telephone can be more
simplified when compared with the conventional ones in the case where the
number of the remote stations is large. Further, since each of the remote
stations is not required to perform the processings relating to the ISDN
nor to store the DDI number and the subaddress, remote stations of the
cordless telephone for use in widely spread analog telephone line network
can be utilized directly as the remote stations of this embodiment. For
example, in case of connecting a cordless telephone for the analog
telephone line network provided in the home to the ISDN line network, the
services of the ISDN can be provided by merely substituting a master
station for the ISDN for that of the analog telephone network.
Accordingly, the cordless telephone of this embodiment can be used widely.
While the embodiment has been described about a case where an incoming
signal is received by the respective remote stations, it will be readily
apparent that the various services capable by the ISDN can be performed in
the master station in case of receiving an incoming signal by the handset
having the speaker 18 and the microphone 19 which are connected to the
controller 12 through the man-machine interface 17.
Further, although the embodiment has been described with respect to the
processings of an incoming signal, the cordless telephone of this
embodiment may be modified such that, upon transmitting an outgoing
signal, the master station 10 can perform various processings associated
with the ISDN. For example, the ISDN interface 11 may prepare messages to
be added to an outgoing signal on the basis of the data stored in the data
memory 22 under the control of the controller 12 and then transmit the
outgoing signal to the ISDN line network i. In this case, the messages
include an attribute of the originating remote station from which the
outgoing signal was transmitted, a DDI number and a subaddress of the
remote station, and a subaddress designated by the remote station etc.
That is, in case of adding an attribute and a subaddress of the
originating remote station to the messages, the controller 12
discriminates the originating remote station, then reads data relating to
the originating remote station from the data memory 22 to discriminate an
attribute and a subaddress thereof, thereby adding the discriminated
attribute and subaddress to the messages.
As set out above, according to this invention, when, to a digital line
network such as the ISDN, there is connected a radio communication
apparatus such as a cordless telephone wherein a radio communication is
performed between a main telephone and sub telephones, the sub telephones
can be controlled at the main telephone side in accordance with a
subaddress or a DDI number included in an incoming signal. Accordingly,
the radio communication apparatus can obtain services such as the
selection of a terminal receiving an incoming signal without detecting a
subaddress or a DDI number of the incoming signal at each of the sub
telephones, so that the constructions of each of the sub telephones can be
simplified.
Having described the preferred embodiment of the invention with reference
to the accompanying drawings, it is to be understood that the invention is
not limited to that precise embodiment and that various changes and
modifications thereof could be effected by one skilled in the art without
departing from the spirit or scope of the novel concepts of the invention
as defined in the appended claims.
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