U.S. patent application number 11/702778 was filed with the patent office on 2009-02-26 for voice conference apparatus, voice conference system and method for realizing a voice conference.
Invention is credited to Xuelei Hu, Juergen Hupp, Thomas Kauppert, Roland Strum, Martin Tittel.
Application Number | 20090052643 11/702778 |
Document ID | / |
Family ID | 35149438 |
Filed Date | 2009-02-26 |
United States Patent
Application |
20090052643 |
Kind Code |
A1 |
Hupp; Juergen ; et
al. |
February 26, 2009 |
VOICE CONFERENCE APPARATUS, VOICE CONFERENCE SYSTEM AND METHOD FOR
REALIZING A VOICE CONFERENCE
Abstract
A voice conference apparatus consists of at least one base
conference block having three or more signal ports, each including
an input for a digitalized voice signal and an output for a
digitalized voice signal, wherein a base conference block is
configured such that, at a signal port, optionally a terminal or
another base conference block may be coupled up using a coupler for
the realization of a voice conference apparatus extended with
respect to the number of participants or in terms of space, and
wherein a base conference block is configured to enable a voice
conference among the terminals or base conference blocks coupled
thereto, and a remote coupler configured to couple a base
conference block with at least one other spatially remote base
conference block in order to enable a spatially extended voice
conference. A voice conference system may be composed of at least
two spatially separate voice conference apparatuses and is
structured in a decentralized and modular way and is flexibly
extensible.
Inventors: |
Hupp; Juergen; (Nuernberg,
DE) ; Tittel; Martin; (Forchheim, DE) ; Hu;
Xuelei; (Erlangen, DE) ; Strum; Roland;
(Nurnberg, DE) ; Kauppert; Thomas; (Nuernberg,
DE) |
Correspondence
Address: |
GLENN PATENT GROUP
3475 EDISON WAY, SUITE L
MENLO PARK
CA
94025
US
|
Family ID: |
35149438 |
Appl. No.: |
11/702778 |
Filed: |
February 5, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/EP2005/008469 |
Aug 4, 2005 |
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11702778 |
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Current U.S.
Class: |
379/93.21 |
Current CPC
Class: |
H04M 3/562 20130101;
H04M 3/56 20130101; H04R 27/00 20130101 |
Class at
Publication: |
379/93.21 |
International
Class: |
H04M 11/00 20060101
H04M011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2004 |
DE |
102004037856.8-42 |
Claims
1. A voice conference apparatus comprising: at least one base
conference block comprising three or more signal ports, each
including an input for a digitalized voice signal and an output for
a digitalized voice signal, wherein a base conference block is
formed such that, at a signal port, optionally a terminal or
another base conference block may be coupled using a coupler for
realizing a voice conference apparatus extended with respect to the
number of participants or in terms of space, and wherein a base
conference block is formed to enable a voice conference among the
terminals or base conference blocks coupled thereto; and a remote
coupler formed to couple a base conference block with at least one
other spatially remote base conference block in order to enable a
spatially extended voice conference, wherein the remote coupler is
further formed for a transmission of synchronization information in
order to synchronize transmitting cycles of mobile units in contact
with various voice conference apparatuses.
2. The voice conference apparatus according to claim 1, wherein the
remote coupler is formed to couple a base conference block with at
least two other spatially remote base conference blocks to which
terminals are coupled in order to enable a voice conference among
the terminals coupled to a total of at least three spatially
distributed base conference blocks.
3. The voice conference apparatus according to claim 1, wherein a
base conference block is formed such that, at each output of a
signal port, a digitally created sum signal of the input signals at
the inputs of the respective other signal ports is present in
digital form.
4. The voice conference apparatus according to claim 1, wherein one
of the couplers includes a radio coupler formed such that a
terminal can be coupled to a base conference block via a wireless
connection.
5. The voice conference apparatus according to claim 4, wherein the
radio coupler is formed such that it enables a wireless connection
between the voice conference apparatus and a terminal according to
the DECT standard or a standard based thereon.
6. The voice conference apparatus according to claim 1, wherein a
talk-listen unit is coupled to the base conference block via a
converter of analog signals to digital signals and a converter of
digital signals to analog signals.
7. The voice conference apparatus according to claim 1, wherein the
remote coupler is formed such that at least one other base
conference block may be coupled to a first base conference block
via a wireless connection.
8. The voice conference apparatus according to claim 1, wherein the
remote coupler is formed such that at least one other base
conference block may be coupled to a first base conference block
via a wire bus.
9. The voice conference apparatus according to claim 8, wherein the
wire bus is formed for a transmission of several voice channels in
time-division multiplex.
10. The voice conference apparatus according to claim 1, wherein
the base conference block is realized by a processor in connection
with suitable operational software.
11. The voice conference apparatus according to claim 10, wherein
the processor is simultaneously used for at least one of the
following tasks: provision of a user interface, coding of data,
realization of a transmission protocol.
12. The voice conference apparatus according to claim 1, wherein a
base conference block with a predetermined number of signal ports
is formed by coupling several sub-conference blocks, each
comprising less than the predetermined number of signal ports,
wherein a sub-conference block is formed such that, at a signal
port, optionally a terminal, another sub-conference block, or a
base conference block may be coupled using a coupler.
13. A voice conference system comprising: at least two spatially
separate base conference blocks comprising three or more signal
ports, each including an input for a digitalized voice signal and
an output for a digitalized voice signal, wherein a base conference
block is formed such that, at a signal port, optionally a terminal
or another base conference block may be coupled using a coupler for
the realization of a voice conference apparatus extended with
respect to the number of participants or in terms of space; and a
remote coupler via which the base conference blocks are coupled to
one another, wherein the remote coupler is further formed for a
transmission of synchronization information in order to synchronize
transmitting cycles of mobile units in contact with various base
conference blocks.
14. The voice conference system according to claim 13, including at
least three base conference blocks that are separated in terms of
space.
15. The voice conference system according to claim 13, wherein at
least two of the base conference blocks are coupled via a wireless
connection.
16. The voice conference system according to claim 13, wherein at
least two of the base conference blocks are coupled via a wire
bus.
17. The voice conference system according to claim 16, wherein the
wire bus is formed for the transmission of several voice channels
in time-division multiplex.
18. The voice conference system according to claim 13, wherein the
voice conference system has at least two terminals, wherein a
duplex voice link exists among all terminals.
19. The voice conference system according to claim 13, wherein one
or more of the terminals are coupled to a base conference block via
a wireless connection.
20. The voice conference system according to claim 19, wherein the
wireless connection to one or more terminals is effected according
to the DECT standard or a standard based thereon.
21. The voice conference system according to claim 13, wherein one
or more of the base conference blocks are part of a DECT base
station.
22. The voice conference system according to claim 13, wherein one
or more of the terminals are DECT mobile units.
23. The voice conference system according to claim 21, wherein the
DECT base stations and the DECT mobile units match in hardware.
24. The voice conference system according to claim 13, wherein a
talk-listen unit is coupled to a base conference block via a
converter of analog signals to digital signals and a converter of
digital signals to analog signals.
25. The voice conference system according to claim 13, wherein a
base conference block is formed such that, at each output of a
signal port, a digitally created sum signal of the input signals of
the respective other signal ports is present in digital form.
26. The voice conference system according to claim 13, wherein a
base conference block is realized by a processor in connection with
suitable operational software.
27. The voice conference system according to claim 26, wherein the
processor is used simultaneously for at least one of the following
tasks: provision of a user interface, coding of data, realization
of a transmission protocol.
28. The voice conference system according to claim 13, wherein a
base conference block with a predetermined number of signal ports
is formed by coupling several subconference blocks, each comprising
less than the predetermined number of signal ports. wherein a
subconference block is formed such that, at each signal port,
optionally a terminal, another subconference block or a base
conference block may be coupled using a coupler.
29. A method for operating a distributed voice conference system
with two base conference blocks coupled to each other via a signal
port each according to claim 13, comprising: reading the
digitalized voice signals from the inputs of the two or more signal
ports of a first base conference block which are coupled to the
terminals; reading the digitalized voice signals from the inputs of
the two or more signal ports of a second base conference block
which are coupled to the terminals; calculating a first sum value
from the read digitalized voice signals of the first base
conference block; calculating a second sum value from the read
digitalized voice signals of the second base conference block;
outputting the first sum value at the output of the signal port of
the first base conference block, which is coupled to a signal port
of the second base conference block; outputting the second sum
value at the output of the signal port of the second base
conference block, which is coupled to a signal port of the first
base conference block; reading the second sum value from the input
of the signal port of the first base conference block, which is
coupled to a signal port of the second base conference block;
reading the first sum value from the input of the signal port of
the second base conference block, which is coupled to a signal port
of the first base conference block; calculating output values at
the outputs of the signal ports of the first base conference block
connected to a terminal by the summation of the values read from
the inputs of the respective other signal ports of the first base
conference block including the second sum value transmitted from
the second base conference block; calculating output values at the
outputs of the signal ports of the second base conference block
connected to a terminal by the summation of the values read from
the inputs of the respective other signal ports of the second base
conference block including the first sum value transmitted from the
first base conference block; and outputting the output values at
the outputs of the signal ports of the two base conference blocks,
which are coupled to terminals.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of copending
International Application No. PCT/EP2005/008469, filed on Aug. 4,
2005, which designated the United States and was not published in
English.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention refers generally to a voice conference
apparatus and a method for realizing a voice conference, and
especially to a distributed digital wireless voice conference
system.
[0004] 2. Description of the Related Art
[0005] Radio-based voice conference systems are utilized wherever
it is not possible to communicate directly within a group of people
due to a large distance, too high a noise level or other reasons.
Several people are to be able to speak to one another via
wireless-connected hearing and/or speaking sets, with everyone
being able to hear all other participants at any time. I.e., there
is a duplex voice link to every participant.
[0006] Thus, in a modern voice conference system a voice link that
is quasi free from delay and full-duplex-capable amongst a large
number of talk-listen units is to be established. Here it is
important for economical reasons to keep the installation
expenditure as low as possible. Furthermore, it is very important
that the system is structured modularly and is flexible to be
extended to a system of quasi any size. Apart from that, it must be
possible that resources already present can be used further. On the
customer side, this particularly refers to cabling as well as
terminals already present. On the producer side, circuit concepts
already present are to be used further. The circuit technology used
is to be easy to realize at low cost. Nowadays, excellent voice
quality is also expected of a modern voice conference system.
Specifically, interference signals coupled into the transmission
link and into a conference node must be very low. Finally, it is
necessary in wireless systems to utilize the radio resources
available as effectively as possible. The sum of these requirements
calls for the refinement of the as yet existing concepts for voice
conference systems.
[0007] According to the prior art, voice conference systems with
base stations coupled in an analog manner or wireless DECT private
branch exchanges are typically used today. In conference systems
with base stations coupled in an analog manner the mobile units
connected to a base station conference with one another. Several
base stations are coupled in an analog manner. The circuit required
here for the forming of a conference includes analog circuit
technology which with high expenditure is to prevent the coupling
in of interferences into the analog signals used. This requires
complex filters and is not feasible in an ideal manner. With a
greater number of participants the interference noises would add up
until the system became impracticable. Therefore, conference
systems with base stations coupled in an analog manner do not meet
the high demands placed on modern voice conference systems.
[0008] The installation expenditure is very high due to the
necessary use of well-screened cables. Even with a low number of
participants, the voice quality is not satisfactory, and
interference effects may easily be coupled in. Also, flexible
extension to a large number of participants is difficult due to the
problems of the interference effects. Finally, today the use of
analog circuit technology involves considerably higher cost
compared to the use of digital circuits.
[0009] Apart from the conference systems with base stations coupled
in an analog manner described above, wireless DECT private branch
exchanges with digital voice transmission are customary today. Here
the conference connection is made in a central unit. This also
involves several disadvantages. Particularly the use of a central
unit able to maintain a large number of radio links simultaneously
is very costly. A modular extension of the system is very difficult
to achieve. In addition, the use of a central unit involves spatial
limitation of the conference system. Finally, the internal
structure of a central unit differs greatly from that of a base
station of a normal, i.e. not conference-capable, cordless
telephone system. This leads to high costs.
[0010] The realization of a conference connection within a central
unit is conventionally effected by the use of a signal processor
adapted to perform the calculations required for the realization of
a voice conference block. An example of such a signal processor is
the SC14428 type by National Semiconductor. For further details
regarding the capabilities of the signal processor, please refer to
the accompanying documentation.
SUMMARY OF THE INVENTION
[0011] Starting from this prior art, it is the object of the
present invention to provide a modular digital voice conference
apparatus, a voice conference system as well as a method for the
operation thereof.
[0012] In accordance with a first aspect, the present invention
provides a voice conference apparatus having at least one base
conference block having three or more signal ports, each including
an input for a digitalized voice signal and an output for a
digitalized voice signal, wherein a base conference block is formed
such that, at a signal port, optionally a terminal or another base
conference block may be coupled using coupling means for realizing
a voice conference apparatus extended with respect to the number of
participants or in terms of space, and wherein a base conference
block is formed to enable a voice conference among the terminals or
base conference blocks coupled thereto; and remote coupling means
formed to couple a base conference block with at least one other
spatially remote base conference block in order to enable a
spatially extended voice conference, wherein the remote coupling
means is further formed for a transmission of synchronization
information in order to synchronize transmitting cycles of mobile
units in contact with various voice conference apparatuses.
[0013] In accordance with a second aspect, the present invention
provides a voice conference system having at least two spatially
separate base conference blocks having three or more signal ports,
each including an input for a digitalized voice signal and an
output for a digitalized voice signal, wherein a base conference
block is formed such that, at a signal port, optionally a terminal
or another base conference block may be coupled using coupling
means for the realization of a voice conference apparatus extended
with respect to the number of participants or in terms of space;
and remote coupling means via which the base conference blocks are
coupled to one another, wherein remote coupling means is further
formed for a transmission of synchronization information in order
to synchronize transmitting cycles of mobile units in contact with
various base conference blocks.
[0014] In accordance with a third aspect, the present invention
provides a method for operating a distributed voice conference
system with two base conference blocks (20, 22) coupled to each
other via a signal port each according to one of claims 13 to 28,
including reading the digitalized voice signals from the inputs of
the two or more signal ports of a first base conference block that
are coupled to the terminals; reading the digitalized voice signals
from the inputs of the two or more signal ports of a second base
conference block that are coupled to the terminals; calculating a
first sum value from the read digitalized voice signals of the
first base conference block; calculating a second sum value from
the read digitalized voice signals of the second base conference
block; outputting the first sum value at the output of the signal
port of the first base conference block, which is coupled to a
signal port of the second base conference block; outputting the
second sum value at the output of the signal port of the second
base conference block, which is coupled to a signal port of the
first base conference block; reading the second sum value from the
input of the signal port of the first base conference block, which
is coupled to a signal port of the second base conference block;
reading the first sum value from the input of the signal port of
the second base conference block, which is coupled to a signal port
of the first base conference block; calculating output values at
the outputs of the signal ports of the first base conference block
connected to a terminal by the summation of the values read from
the inputs of the respective other signal ports of the first base
conference block including the second sum value transmitted from
the second base conference block; calculating output values at the
outputs of the signal ports of the second base conference block
connected to a terminal by the summation of the values read from
the inputs of the respective other signal ports of the second base
conference block including the first sum value transmitted from the
first base conference block; and outputting the output values at
the outputs of the signal ports of the two base conference blocks,
which are coupled to terminals.
[0015] The present invention provides a voice conference system
with at least one base conference block comprising three or more
signal ports, each including an input for a digitalized voice
signal and an output for a digitalized voice signal, a base
conference block being adapted such that optionally a terminal or
another base conference block for the realization of a voice
conference apparatus extended with regard to the number of
participants or with regard to space may be coupled to a signal
port with the help of coupling means, and a base conference block
being adapted to facilitate a voice conference amongst the
terminals or base conference blocks coupled to the same and remote
coupling means adapted to couple a base conference block with at
least one other spatially remote base conference block so as to
enable a spatially extended voice conference.
[0016] Apart from that, the present invention provides a voice
conference system as well as a method for operating a voice
conference system.
[0017] The present invention is based on the finding that with a
fully digital realization of voice signal processing and
transmission, high voice quality can be guaranteed, interferences
can be effectively suppressed, and system costs can be reduced by
the use of digital circuit technology. Moreover, the present
invention is based on the finding that by the use of base
conference blocks which are flexibly connectable a modular, quasi
arbitrarily extensible voice conference system can be constructed
with little expenditure. A decentralized formation of
subconferences, which is enabled by the fact that spatially
separate base conference blocks can be coupled to one another,
renders a costly central unit unnecessary.
[0018] Individual nodes of the conference system now differ only in
terms of software, however not in terms of hardware.
[0019] The transmission of the digital voice signals between
several base conference blocks enabled by the use of remote
coupling means permits a spatially extended voice conference with
high voice quality, a single base conference block calculating a
local subconference, which leads to a distribution of the
calculation expenditure involved and reduces the amount of data to
be transmitted compared to conventional centralized conference
systems.
[0020] Thus, the present voice conference system differs from the
systems according to the prior art specifically in that voice
transmission and voice processing are effected completely digitally
without requiring a central station defined by special features in
terms of hardware. On the contrary, the bulk of the signal
processing is effected in a decentralized manner. Such a voice
conference apparatus and/or such a voice conference system involves
a number of advantages. Specifically, voice quality is high due to
digital processing and transmission, and the susceptibility to
interferences is low. The distributed realization reduces hardware
expenditure and installation costs as the cabling is simplified
considerably compared to conventional systems. Modularity ensures
flexible extension. A node used in such a distributed voice
conference system differs, apart from remote coupling means
enabling the spatial extension, only little in hardware from that
used in a normal telephone system so that hardware already present
may continue to be used with only few modifications. It is possible
to assemble a voice conference system from a plurality of spatially
distributed units that are substantially identical in hardware.
[0021] In one embodiment of the present voice conference apparatus
a base conference block is adapted such that to each output of a
signal port a digitally formed sum signal of the input signals of
the respective other signal ports is present in digital form. This
is advantageous in that the digital processing enables very simple
summation. Moreover, signal reflection, i.e. outputting the voice
signal read from the input of a signal port to the output of the
same signal port, can be inhibited. Finally, such a configuration
of the base conference block enables an arbitrary extension of the
system, it only being necessary to transmit digital signals on all
links.
[0022] In another preferred embodiment one or more terminals are
coupled to a base conference block via a wireless connection, which
is enabled by a suitable configuration of the remote coupling
means. The wireless connection to one or more terminals can be
specifically effected according to the DECT standard or a standard
based on the same. The wireless connection is advantageous in that
the conference participants can move freely around the room. Here
the transmission of the voice signals according to a digital
standard enables high voice quality with good suppression of
interferences and good utilization of the frequency resources
available. The conversion of the audio signals into digital signals
and vice versa is performed directly in the terminal. Moreover, if
the wireless connection is made according to the DECT standard or a
standard based on the same, standard terminals and base stations
that already exist and ones which are available at low prices can
be used.
[0023] In another embodiment a talk-listen unit is coupled to a
base conference block via means for the conversion of analog
signals into digital signals and means for the conversion of
digital signals into analog signals. This enables the operation of
a talk-listen unit positioned at the same location as the base
conference block. Thus, an additional stationary user may be
integrated into the voice conference at little expenditure.
[0024] In another embodiment, one or more base conference blocks
are coupled to a first base conference block via a wireless
connection. This is advantageous in that the voice conference
apparatus may be extended without any installation expenditure.
Such a solution is further advantageous in that the frequency
resources available can be utilized effectively. The only
prerequisite is that the transmitting power of the mobile units
must be high enough to reach the nearest base conference block
while the possibly more remote base conference blocks communicate
with one another via a radio link with greater transmitting
power.
[0025] In another preferred embodiment one or more further base
conference blocks are coupled to a first base conference block via
a wire bus. Here, too, it is the object of the remote coupling
means to enable and manage the connection. Particularly
advantageously, the wire bus is configured for transmitting several
voice channels in time-division multiplex. Such an arrangement is
advantageous in that a voice conference apparatus may be extended
in any desired manner in terms of space without occupying frequency
resources in the process. By means of a wire bus almost any
distance may be bridged. Specifically, the transition to wide-area
telephone networks is possible. The transmission of several voice
channels in time-division multiplex on one bus is advantageous in
that a plurality of connections may be established at low
installation expenditure. The use of the bus principle in cabling
here eliminates the restraint of having to determine as early as at
the installation of the system which of the communication nodes is
to take on which function. Rather, each connected device is equal
with regard to the installation, and not until the operation of the
system is it decided which function in the data transmission is to
be fulfilled by the respective device. The use of a
time-division-multiplex method reduces the hardware expenditure
compared to frequency-division-multiplex methods, which require
extensive modulation and frequency conversion. Furthermore, a
time-division-multiplex method with fixedly defined time slots for
each transmission channel is thoroughly real time capable, which is
not guaranteed for other network systems using, for example,
collision detection.
[0026] In another preferred embodiment a base conference block is
realized by a processor in connection with suitable resident
software. Here, the processor can be used further for providing a
user interface, for encoding data, or for realizing a transmission
protocol. Such an arrangement is advantageous in that an existing
processor may be used for the realization of the voice conference.
Accordingly, no additional hardware to that already present is
required for the realization of the voice conference. In addition,
the realization of a base conference block by means of a processor
is advantageous compared to a hard-wired solution in that changes
in the functionality may be achieved solely by changing the
software. This reduces development costs and permits a very
universal and flexible system that can be re-configured even during
runtime.
[0027] In another preferred embodiment a base conference block with
a predetermined number of signal ports is formed in that several
sub-conference blocks, each of which comprising less than the
predetermined number of signal ports, are coupled to one another.
This concept is advantageous in that a base conference block can be
assembled modularly from several sub-conference blocks of the same
kind. Accordingly, it suffices to provide several small conference
blocks. This results in the standardization of the required
hardware and/or software, which involves a substantial reduction in
costs. Furthermore, this concept is the basis for distributed
system realizations.
[0028] A voice conference system includes at least two base
conference blocks as described above as well as a means via which
the base conference blocks are coupled to one another. In one
preferred embodiment of a voice conference system at least two of
the base conference blocks are separated in terms of space. This
makes the realization of a distributed voice conference system
possible.
[0029] In one embodiment at least two of the base conference blocks
are coupled via a wireless connection. This in turn enables
flexible extension of the voice conference system without any
installation expenditure.
[0030] In another embodiment at least two of the base conference
blocks are coupled by means of a wire bus. Particularly
advantageously, the wire bus is configured for transmitting several
voice channels in time-division multiplex. The advantages of such
an embodiment have already been explained in detail above.
[0031] In another embodiment the voice conference system comprises
at least two terminals, a duplex voice link being present among all
existing terminals. This is advantageous in that all the
individuals taking part in the voice conference are able to listen
and talk simultaneously. Thereby the voice conference system
imitates the presence of all participating individuals in a common
place in a good way.
[0032] In another embodiment of a voice conference system, one or
more of the base conference blocks are part of a DECT base station.
Furthermore, one or more of the terminals may be DECT mobile
stations. Such an embodiment is advantageous in that a voice
conference system may be integrated into an existing DECT system
without any great expenditure. This guarantees compatibility
particularly with existing terminals. It also ensures a digital
wireless transmission of the voice signal with little interference.
Furthermore, on the producer side the expenditure for the
development of the hardware for the telephone conference system is
low, as existing components can be used further with only minor
alterations to be made.
[0033] In another preferred embodiment the DECT base stations and
the DECT mobile stations are identical in terms of hardware. This
is advantageous in that the number of hardware variations within
the system is reduced, which decreases manufacturing costs and
enables flexible re-configuration of the system at any time. The
system characteristics are defined solely by software, which may be
easily replaced.
[0034] The present invention further provides two methods for
operating a voice conference apparatus or a voice conference
system. The methods are effectuated particularly in the operation
of a base conference block, wherein the realization may be effected
both in hardware and by a microprocessor in connection with a
suitable program. The present methods are advantageous in that the
processing of digitalized voice signals required for the
realization of a voice conference may be performed in a very simple
and universal manner. Two methods may be used, wherein the first
method according to claim 17 is of advantage if only one local
voice conference is to be realized or if the demands placed on the
time coordination of the voice signals are low. In a second method
according to claim 18, the processing of the data supplied by local
terminals and the processing of the sum signals supplied by other
base conference blocks is effected in separate steps. Such a method
is of advantage if the demands placed on the time coordination of
the voice signals in a voice conference system that is distributed
widely in terms of space are very high. With such a method, in
particular delays occurring on the transmission path may be offset
virtually completely, so that all participants can be heard
simultaneously, independent of their current location and of their
distance to one another.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] These and other objects and features of the present
invention will become clear from the following description taken in
conjunction with the accompanying drawing, in which:
[0036] FIG. 1 shows a system diagram of an embodiment of a voice
conference system;
[0037] FIG. 2 shows a block diagram of an embodiment of a base
conference block with a maximum of four participants;
[0038] FIG. 3 shows a block diagram of an embodiment of a
conference block with six participants;
[0039] FIG. 4 shows a block diagram of an embodiment of a
conference block with nine participants;
[0040] FIG. 5 shows a flow diagram of an embodiment of a method
according to the invention for operating a voice conference
system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] FIG. 1 shows a system diagram of an embodiment of a voice
conference system that in its entirety is designated by 10. The
voice conference system includes a master base station 12 as well
as four similar slave base stations 14, two of which are shown here
representatively. The core of the master basis station 12 is a
conference block 20 with nine inputs. The core of a slave base
station is a conference block 22 with six inputs. One talk-listen
unit 24 as well as four mobile units 26 capable of transmitting
digital audio signals via a bi-directional radio link are coupled
to master base station 12 as well as each of slave base stations
14. Here, talk-listen units 24 are connected in an analog manner to
the respective conference blocks, while the digitalized voice
signals are exchanged in an ADPCM-encoded manner with DECT mobile
units 26. ADPCM stands for adaptive differential pulse code
modulation. The coupling of the talk-listen units 24 is
accomplished via means 27 for the conversion of analog signals into
digital signals and vice versa, the coupling of DECT mobile units
26 is accomplished via radio coupling means 29. Slave base stations
14 are connected to master base station 12 via serial bus 30. Here,
the provision and processing of the bus signals is taken over by
one remote coupling means 31 in each of base stations 12, 14.
Serial bus 30 substantially includes three lines, a data line 32,
on which the data of four voice channels are transmitted in
time-division multiplex, a line 34 for the bit clock, and a line 36
for the frame clock.
[0042] The core of master base station 12 is a conference block
with nine participants 20, and the core of a slave base station 14
is a conference block 22 with six participants. The structure and
mode of operation of the conference blocks with nine participants
and six participants 20, 22 will be explained in the following with
regard to FIGS. 2 to 4 before the mode of operation of the entire
voice conference system 10 will finally be explained with regard to
FIG. 1.
[0043] FIG. 2 shows a block diagram of an embodiment of a base
conference block with a maximum of four participants, which in its
entirety is designated by 50. Base conference block 50 for a
maximum of four participants comprises four signal ports 52, each
comprising one input 54 for a digitalized voice signal and one
output 56 for a digitalized voice signal. Here, the digital input
signals at the four signal ports 52 are designated by A, B, C and
D. Circuitry in the interior of base conference block 50 is
configured such that it reads input signals 54 from the four signal
ports 52 and at each of the four outputs 56 outputs the sum of
input signals 54 at the other signal ports 52. Here, signal
processing within a base conference block is effected in a fully
digital manner. Thus, the base conference block realizes the core
characteristics of a conference circuit. The input signal from
input 54 of a signal port 52 is transmitted to the outputs 56 of
the respective other signal ports 52 but not to the output 56 of
the dedicated signal port 52.
[0044] FIG. 3 shows a block diagram of an embodiment of a
conference block with six participants, which in its entirety is
designated by 70. The same is established by interconnecting two
base conference blocks 50a, 50b with four inputs each. Therefore, a
total of six signal ports 72 are available. Here, each base
conference block 50a, 50b provides three external signal ports 72,
74, 76. Via one signal port 52 of each of the two base conference
blocks 50a, 50b a connection is made between these two. Here, too,
the circuit and the inner structure of the base conference blocks
ensure that to the output of each of the external signal ports 72,
74, 76 the digitally formed sum of the input signals of the other
signal ports 72, 74, 76, respectively, is applied.
[0045] FIG. 4 shows a block diagram of an embodiment of a
conference block with nine participants, which in its entirety is
designated by 90. The same includes four base conference blocks
50c, 50d, 50e, 50f with four signal ports each and comprises nine
external signal ports 92, 94, 96. A first base conference block 50c
provides three external signal ports 92, 94 and at one signal port
is connected with another second base conference block 50d. the
second base conference block 50d provides two external signal ports
92 and at one signal port each is connected to the first base
conference block 50c and a third base conference block 50e. The
latter again provides two external signal ports 96 and at its
fourth signal port is connected to a fourth base conference block
50f. The fourth base conference block 50f again provides two
external signal ports 92. One signal port of the fourth base
conference block 50f is not wired up. Thus, a total of nine
external signal ports 92, 94, 96 are provided. To each output of an
external signal port the sum of all inputs with the exception of
the dedicated signal port is applied.
[0046] The description of the base conference block 50 as well as
the extended conference blocks with six participants 70 and/or nine
participants 90 shows that based on a small base conference block
with a given number of signal ports larger conference blocks with
more signal ports can be assembled by means of suitable circuitry.
The essential characteristics of the signal blocks, in particular
the fact that an input signal is transmitted to the outputs of all
other signal ports but not to the output of its own signal port,
are maintained.
[0047] Based on the understanding of base conference blocks 50 and
extended base conference blocks 70, 90 with six participants or
nine participants respectively, now the mode of operation of voice
conference system 10 according to FIG. 1 will be discussed. In the
present embodiment, both master base station 12 and slave base
stations 14 are similarly structured DECT base stations. In the
present embodiment, mobile units 26 are DECT mobile stations. The
base stations may also be operated in a mobile manner. In the
present embodiment the base stations and mobile stations have
identical structures in terms of hardware, and are configured as
radio modules. The difference consists solely in the loaded
software (firmware). Both for base stations and for mobile
stations, each DECT derivative may be used in different frequency
bands DECT in the 2.4 GHz band with a frequency-jump method. The
audio signals are transmitted via air between base stations 12, 14
and mobile units 26 in an ADPCM-encoded manner, according to the
DECT standard. Respective conversion into PCM-encoded signals is
feasible, and is effected within the mobile units and within the
base station.
[0048] As a whole, transmission across the air link is effected
largely transparently so that it can be assumed that the voice
signal received by the respective mobile units 26 is present in
digitalized form at the inputs of signal ports 92, 72 and that the
digitalized voice signal present at the outputs of signal ports 92,
72 is outputted via the loudspeakers of the associated mobile units
26. A bi-directional analog/digital converter circuit connected
between the talk-listen unit 24 and conference blocks 20, 22
ensures that the microphone signal of a respective local talk unit
is present in digital form at the DECT base station at the input of
the associated signal port 94, 74 and that the digital voice signal
is outputted at the output of signal port 94, 74 at the local
loudspeaker.
[0049] A difference is made here between a local conference, which
only includes the mobile units 26 connected to the respective base
station as well as local talk-listen unit 24, and a global
conference, wherein the local conferences of the respective base
stations 12, 14 are combined to form an overall conference. Per
base station, several mobile stations may be operated in a local
conference connection. Therefore, in a local conference, all
participants connected directly to a base station are able to speak
to one another. Here, the connection between the base stations is
at first not taken into account. The local conference is achieved
by adding the PCM-encoded voice signals from the mobile units 26
and the local talk-listen unit 24 in a conference block 20, 22 such
that at the output of a signal port 92, 94, 72, 74, the sum of the
input signals of all other signal ports 92, 94, 72, 74 of a
conference block is present. The practical implementation of this
calculation rule is comparably easy to achieve by digitally adding
the voice signals present in PCM-encoded form in the DECT processor
of base station 12, 14. The formation of a local conference
therefore does not result in any additional circuit complexity.
Here, the maximum number of mobile units 26 per base station 12, 14
is determined by the system properties of base station 12, 14, for
example by the maximum number of simultaneous radio connections and
the maximum number of voice channels that may be used
simultaneously.
[0050] Starting from the procedure for the formation of a local
conference just described, a global conference where participants
at all terminals 24, 26 connected to all base stations 12, 14 can
speak to one another simultaneously, can be established. Here, the
local conferences are advantageously combined to form larger
distributed conferences. The subconference signals are exchanged
among the base stations in digital form (PCM-encoded). In order to
achieve this, base stations 12, 14 are connected via a wire serial
bus 30, on which several logical channels are transmitted in
time-division multiplex. One of the base stations, that have
identical structures in terms of hardware, assumes the role of a
master (master base station 12) by appropriate configuration. The
master is responsible for combining the subconferences of the other
base stations (slave base stations 14). Furthermore, master base
station 12 performs the synchronization of serial bus 30. A logical
bi-directional connection between master base station 12 and each
of slave base stations 14 is established via wire serial bus 30.
The transmission in both directions and between master 12 and the
respective slave base station 14 is effected by means of logical
channels in time-division multiplex. The digitalized voice signals
are transmitted PCM-encoded via this link. Thus, the bus connection
between master base station 12 and slave base stations 14 is also
transparent, i.e. equal to a direct bi-directional point-to-point
connection between master base station 12 and each of slave base
stations 14. All tasks of bus management are fulfilled by remote
coupling means 31.
[0051] Thus, the master base station essentially corresponds to a
conference block 20 with nine participants which is connected to
four mobile talk-listen units 26, a local talk-listen unit 24 as
well as four other conference blocks 22. A slave base station
essentially corresponds to a conference block 22 with six
participants which is connected to four mobile talk-listen units
26, one local talk-listen unit 24 and base conference block 20.
[0052] Thus, the operation of the overall voice conference system
is to be understood in detail as follows: In each mobile unit 26 a
wirelessly received input signal is outputted in an analog manner
at the loudspeaker of the respective talk-listen unit. The
microphone signal of the talk-listen unit of each mobile unit 26 is
digitally transmitted to respective base station 12,14. In the
slave base stations, an input signal received by a local mobile
unit 26 via air is outputted in an analog manner to the local
talk-listen unit 24 as well as digitally passed on to the other
local mobile units 26 and to master base station 12. The microphone
signal at the local talk-listen unit 24 of a slave base station 14
is transmitted digitally to master base station 12 and to local
mobile units 26. Furthermore, in slave base station 14 the signal
coming from master base station 12 is outputted in an analog manner
at talk-listen unit 24 as well as digitally transmitted to local
mobile units 26.
[0053] In master base station 12, an input signal received by a
local mobile unit 26 via air is outputted in an analog manner to
local talk-listen unit 24 as well as digitally passed on to the
other local mobile units 26 and to all slave base stations 14. The
microphone signal at the local talk-listen unit 24 of the master
base station is digitally transmitted to all slave base stations 14
and to the local mobile units 26. Furthermore, in master base
station 12, the signal coming from a slave base station 14 is
outputted in an analog manner at talk-listen unit 24 as well as
digitally transmitted to the other slave base stations 14 and local
mobile units 26.
[0054] Thus, in master base station 12, the local conference of the
master base station is combined with the local conferences of slave
base stations 14. Therefore a considerable part of the calculation
expenditure involved is transferred to slave base stations 14, in
each of which a local subconference is already calculated. In
particular, not all terminals 24, 26 must have a (direct or
logical) connection to a central base station. The transmission of
appropriate sum signals, as described above, is sufficient. This
significantly reduces the requirements for the connection between
the terminals and the central station.
[0055] It is obvious that the shown embodiment is not the only
realization of the present invention. On the contrary, the voice
conference system described herein can be altered in a wide range.
By way of example, the number of mobile units and local talk-listen
units may be altered. In the embodiment described one master base
station and four slave base stations are used. Each of the base
stations is connected to and synchronized with four mobile units
via a radio link. Therefore the mobile stations can establish or
disconnect a radio link with audio signal transmission to the
associated base station. Furthermore, the base station comprises a
local talk-listen unit. Therefore the voice conference system
described above is suitable for the establishment of a voice
conference, of up to 25 participants.
[0056] Depending on the requirements and technical possibilities,
the number of mobile stations per base station may be varied.
Furthermore, the local talk unit at the base station may be omitted
or more than one local talk unit may be used. The number of slave
base stations may be increased if, at the same time, the number of
logical channels on the serial bus connecting the slave base
stations to the master base station is increased. It may readily be
seen that the scalability on a local and global level is a great
advantage of the inventive voice conference system.
[0057] In another embodiment of the present invention, the
connection between the master base station and the slave base
stations can be realized in a different manner. The wire serial bus
may be replaced by any other connection as long as a voice
transmission with sufficient quality and little temporal delay is
guaranteed. In particular, any high-speed bus system may be used.
Furthermore, it is conceivable to connect several base stations via
a (preferably digital) public telephone network. Such a solution is
advantageous in that the voice conference system may be extended
greatly in terms of space. Furthermore, the connection between the
master base station and the slave base stations may also be
effected in a wireless manner. This is advantageous in that
installation expenditure is significantly reduced. Basically it is
also conceivable to implement a voice conference system according
to the present invention as an ad hoc system. I.e., the
configuration of the system and particularly the configuration of a
wireless device as terminal, as master base station, or as slave
base station is effected automatically. This is possible as there
is no difference in hardware between terminal, master base station,
and slave base station. Accordingly, the hardware is very
universally applicable and any configuration of the voice
conference system can be achieved easily.
[0058] In another embodiment, the DECT base stations and DECT
mobile stations may be replaced by base stations and mobile
stations conforming to another standard. In the signal transmission
to the mobile units as well, the ADPCM coding may be replaced by
any signal coding. Therefore the voice conference system according
to the present invention is not bound to any particular
communication standard.
[0059] Furthermore, the link between several base stations may be
used not only for the transmission of digitalized voice signals,
but also for the transmission of synchronization information.
Especially the transmitting frequencies and transmitting cycles of
the mobile units in contact with the various base stations may be
synchronized. This allows a more efficient utilization of the
frequency resources.
[0060] For example, a first time-division multiplex transmission
between a first base conference block and the mobile units in
contact with the first base conference block and a second
time-division multiplex transmission between a second base
conference block and the mobile units in contact with the second
base conference block may be coordinated in terms of time and/or
frequency. This allows to accomplish that, in the first
time-division multiplex transmission, only time slots are used that
are not used in the second time-division multiplex transmission,
and vice versa. For this purpose, information on a frame structure
of the time-division multiplex transmission between the base
stations and the mobile units may be transmitted among the base
stations over the link between the base stations so that, for
example, the base stations involved can use the same frame
structure for the communication with the mobile units. Thus,
transmitting cycles of the base stations and/or of the mobile units
in contact with various base stations may be coordinated.
[0061] Here, the frame structure of the time-division multiplex
transmission specifies, for example, time slots allocated to the
individual base stations and/or mobile units, or details of the
association of time slots with base stations and/or mobile units.
By way of example, the frame structure may provide that, with a
total of N mobile units, the n.sup.th (1<=n<=N) time slot of
a frame is allocated to the communication between the n.sup.th
mobile unit and the associated base station (wherein in turn a
first part of the n.sup.th time slot may be allocated to a
transmission from the base station to the mobile unit, and a second
part of the n.sup.th time slot may be allocated to a transmission
from the mobile unit to the associated base station). A frame may,
moreover, include further synchronization information.
[0062] Thus, the frame structure may be made known to all
participants (base stations and preferably mobile stations as well)
by the connection between the base stations. Apart from that, the
frame structure of the time-division multiplex transmission may
also be adapted dynamically to the number of mobile stations
present. A (data) transmission rate required by the individual
mobile stations can also be taken into consideration when
determining the frame structure.
[0063] The described coordination of the frame structure
facilitates, for example, the management in the case of movement of
a specific mobile station. If the specific mobile station moves
from the coverage area of a first base station into a coverage area
of a second base station, it is possible, using the inventive base
stations with a remote coupling means for the transmission of
synchronization information, to transmit a time slot of the
time-division-multiplex frame structure, in which the first base
station has communicated with the specific mobile station, to the
second base station for a communication with the specific mobile
station. The transmission of the respective synchronization
information may be effected via the remote coupling means. This
enables "roaming", i.e. the transfer of a mobile unit from one base
station to another base station without exchanging synchronization
information with the mobile unit. Synchronization is instead
performed among the base stations using the remote coupling
means.
[0064] It is, however, also possible to use a fixed frame
structure, which is distributed from a central base station to all
other base stations via the remote coupling means and is also
transmitted to the mobile units, if necessary.
[0065] Apart from that, it is to be noted that via the remote
coupling means not there may not only be exchanged information on
the frame structure among the base stations, but there may also be
performed a time synchronization of the base stations, so that all
base stations simultaneously recognize a beginning of a frame.
[0066] The implementation of a base conference block may also be
altered greatly. The realization is possible both by a processor in
connection with a suitable program and in hardware, for example in
the form of a programmable logic unit or an application specific
integrated circuit. Furthermore, the base conference block may be
realized either as a whole or, as shown, be divided into
sub-blocks. The form to be preferred basically depends on the
realization form present and on the number of signal ports
required.
[0067] In another embodiment, the hierarchical structure, where a
difference is made between the master base station and the slave
base station, can be eliminated. For the operability of a voice
conference system according to the present invention, the fact that
a digitalized voice signal can be transmitted from any conference
block to any other conference block is sufficient. If the latencies
in the transmission are low, then the number of interposed
conference blocks will be of no importance. Specifically it is
sufficient that there is a point-to-point connection between every
two adjacent conference blocks. Such a system configuration
corresponds to the one shown in FIG. 4, while the base conference
blocks may also be separated in terms of space.
[0068] In another embodiment, several local subconferences may be
formed as well. The calculation may be performed both decentralized
and in a master base station. In particular, it is possible to
determine which station is to act as the master base station during
runtime of the system.
[0069] FIG. 5 shows a flow diagram of an embodiment of a method
according to the invention for operating a voice conference system
with two base conference blocks. The method is performed in
parallel in two base conference blocks, wherein the method steps in
the first conference block are designated by 110 and the method
steps in the second conference block are designated by 112. In a
first step, in both base conference blocks, digitalized voice
signals are read from the inputs of two or more signal ports
coupled to terminals. In a second step, the signal values read from
the terminals are added in both conference blocks. The sum value is
then outputted at a signal port connected to the respective other
conference block. Accordingly, the sum value outputted by the
respective other conference block is then read. Finally, output
values for the signal ports connected to the terminals are created
in each conference block by summation of the signal values read
from the respective other signal ports connected to terminals and
the sum values transmitted by the other base conference block. In a
last step, they are outputted to the terminals.
[0070] The inventive method thus generates a clear temporal
sequence in the summation and in the exchange of sum values among
several conference blocks. The locally created sum values must
first be exchanged among the base conference blocks involved,
before the final output value for the terminals can be calculated.
Such a method is necessary particularly when the transmission time
between individual conference blocks is long due to a large run
time on the transmission link. The aforementioned method thus makes
it possible that the signals of all participants are outputted
simultaneously at a terminal, irrespective of whether they are
connected to the same conference block as the terminal or to a
spatially remote conference block.
[0071] The present invention thus provides a voice conference
system enabling a voice conference with very high voice quality.
The audio signals are converted directly at the microphones into
digital signals which are significantly more resistant to
interference coupling than analog signals. The decentralized
formation of subconferences renders a complex central unit
superfluous. The base stations and the mobile units may be
identical in terms of structure and differ only in the respective
operational software. In particular, a voice conference system
using the base conference blocks according to the invention may be
very flexibly configured and adapted to a large number of digital
communication standards.
[0072] While this invention has been described in terms of several
preferred embodiments, there are alterations, permutations, and
equivalents which fall within the scope of this invention. It
should also be noted that there are many alternative ways of
implementing the methods and compositions of the present invention.
It is therefore intended that the following appended claims be
interpreted as including all such alterations, permutations, and
equivalents as fall within the true spirit and scope of the present
invention.
* * * * *