Note: Descriptions are shown in the official language in which they were submitted.
2068941
Device and method for telephony interconnection intended
to offer continuity of service to independent stations in
a communications network.
FIEI.D OF THE lNV~;N'l'ION
The invention relates to telephony.
It is more particularly intended to serve in a c~ n;ca-
tions network between fixed stations, such as telephone
sets~ and fixed terminals, the said fixed stations being
linked to the telephony channels of the network while the
fixed tP ;n~l s comprise means forming an antenna (more
simply called "antenna" in the rest of the text) for
mutual interaction over distance with independent
stations, such as portable telephone handsets.
PRIOR ~RT
Such a network is, for example, that ~nown by the trade-
mark POINTEL, and the invention finds à particularly
advantageous but not limiting application therein.
The POINTEL network does not permit, in its current
definition, offering the user of a portable handset
continuity of service, when the latter moves, even if all
the fixed terminals situated in the vicinity of the user
provi'de complete radio frequency coverage. In fact, it is
anticipated currently that the telephony co~nn;cation in
progress will be broken off as soon as the user moves out
of the radio frequency zone covered by the fixed terminal
having initialized the radio frequency link of this
telephony c.- n i cation.
SUMMARY OF T~E lNv~NllON
The invention aims to provide a solution to this problem.
According to a general characteristic of the invention,
the telephony device, intended to serve in a c~ n; ca-
tions network of the type quoted a~ove, comprises:
- means of interface with the antennae of a plurality of
fixed terminals,
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2068941
- means of connection to the telephony channels of the
network, and
specific means, linked to the interface and connection
means, suitable for:
establishing a telephony relationship between an
independent station and another station, in principle a
fixed telephony set, linked to the telephony channels of
the network, by the intermediary of a primary link
between the independent station and the connection means,
via the antenna of a primary fixed terminal,
and for establishing at least one secondary link between
the independent station and the said connection means,
via the antenna of a secondary fixed termin~l, chosen on
the basis of predetermined selection criteria,
- station-analysis means, incorporated in the independent
station, suitable for generating a predetermined request
information item in response to a predetermined station
condition relating to the primary link.
The specific means are then, moreover, suitable for
responding to th~ reception of this request informa'ion
item, by switching the said telephony relationship so
that it passes through this secondary link.
This secondary fixed terminal is advantageously selec-
table among a chosen group of terminals which are
adjacent to the primary fixed term; n~l .
According to an embodiment of the device, the inter~ace
means comprise, with respectively the antennae of the
primary and secondary fixed tPrm; n~l s~ first primary and
se~ondary interface stages for a plurality of radio
~ 3~ frequency channels, while the specific means comprise:
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2068941
- primary terminal-processing means, linked to the said
first primary interface stage, suitable for establishing,
within the said primary link, a primary radio frequency
link between the independent station and the antenna on
at least one of the radio frequency channels of this
primary fixed terminal, for characterizing this primary
radio frequency link one-two-one by a link identifier,
and for delivering this link identifier to a second
primary interface stage,
- transfer means linked to this second primary interface
stage, suitable for receiving the said link identifier
and for c~ n; cating to a second secondary interface
~ stage, situated at the site of the secondary fixed
t~rrin~l, a link information item containing at least
this link identifier, and
- secondary t~ ;n~l-procesqing means, linked to the said
first and second secondary interface stages, suitable for
establishing, within the said secondary linkl a secondary
radio frequency link between the independent station and
the antenna on at least one of the radio frequency
channels of this secondary fixed terminal, with the aid
of the said link identifier.
The request information item then ad~antageously contains
this link identifier.
The selection criteria for the secondary fixed terminal
! can result from the analysis of at least one first
characteri~tic deduced from the pri~ary radio frequency
signal transmitted in the course of the primary radio
frequency link on at least one of the radio frequency
channels of the Drimary fixed terminal, and from analysis
of at least one second characteristic deduced from this
primary radio frequency signal.
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20689~1
This first characteristic is, preferably, det~rm;n~tionof the level of the said primary radio fre~uency signal
in the primary fixed terminal while the second charac-
teristic comprises, preferably, dete ination of the
level of the radio freq-lency activiky resulting from the
transmission of the primary radio frequency signal, on
the radio frequency channel associated with the secondary
fixed terminal, the counterpart of the radio frequency
channel associated with the primary fixed terminal, on
which the said primary radio frequency signal is trans-
mitted.
According to one embodiment of the invention, at least
part OI the constituent parts of the device can be
incorporated in at least one specific module.
It is also possible for these constituent parts to be
incorporated within at least some of the connecting units
for the fixed terminals belonging to the c~ n;cations
network.
The subject of the invention is also a method for tele-
phony interconnection, intended to serve in a
Cl: n;cations network of the type quoted above, in which
method there is provided:
- means OI connecting to the telephony channels of the
network,
there is established a telephony relationship between an
independant station and another s~ation linked to the
telephony channels of the network, by the intermediary of
a primary link between the independent station and the
connecting means, via the antenna of a primary fixed
3 0 t~rm; n~ 1 ~
there is chosen a secondary fixed teL ; n~l on the basis
OI predetermined selection criteria,
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2068941
there is established a secondary link between the
independent station and the said connection means, via
the antenna of the said secondary fixed terminal,
in response to a predetermined station condition~
relating to the said primary link, there i5 generated,
from the independent station a predetermined request
information item, and in response to reception of the
said request information item, the said secondary
relationship is switched.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages and characteristics of the invention
will appear on P~;n;ng the detailed description below
and the attached drawings in which:
- Figure 1 represents a block diagram of a communications
network of the POINTEL type of the prior art;
- Figure 2 represents a block diagram of a first
configuration of a cl- n;cations network equipped with
means according to the invention;
- Figure 3 represents a block diagram of a specific
modu~e belonging to the davice according to the
invention;
- Figures 4, 5 and 6 diagrammatically illustrate other
means of the device according to the invention; and
- Figure 7 represents a second configuration of a
c~ n;cations network equipped with means according to
the invention.
The drawings essentially comprise elements of a speci~ic
nature. That being so, they can serve not only to make
the detailed description below better understood, but
also to contribute, if need be, to the definition of the
invention.
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20689~1
DESCRIPTION OF THE PREFERRED EM~ODIMENTS
It is assumed now that the invention applies to the
POINTEL network whose structure provided up to the
present will now be very briefly described with reference
to Figure 1.
Independent stations SA, such as portable telephone
handsets, are capable of mutual interaction o~er distance
with a radio channel with antennae ANT of fixed radio
tPrm i na 1s BFR.
The radio frequency exchanges between the independent
stations and the terminals are governed by a standard of
British origin called "CAI" ("Common Air Interface"). The
exchanges take place by frequency modulation making use
of one frequency band per radio c~ n; cation.
These fixed tPrri n~l s BFR ~are connected to terminal
connecting units URB by a specialized control channel
CCS. Each teL ; n~l connecting unit thus manages a group
of fixed terminals BFR.
A fixed terminal can be directly connected to the
tele~hony channels CTPU of the public switched telephor.e
networks. In this case the unit URB which manages it is
not connected to these telephony channels.
A fixed terminal may not be directly connected to the
telephony channels CTPU. In this case, its connection is
carried out by the intermediary of its connec~ing unit
which is then directly connected to~the channels CTPU.
Each fixed ter~i n~l BFR can only send out telephone calls
towards the telephony channels CTPU but can certainly
send out or receive radio calls destined for or originat-
ing from independent stations SA.
.
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The communications networ~ comprises, in addition to the
telephony channels CTPU, a digital co n; cations medium
CNPU, operating, in principle, by packets, such as -the
TRANSPAC ~registered trademark) network. In the rest o~
the text, the expression "communications medium" will be
replaced by the term "channel" for the sake of
uniformity, although the person skilled in the art knows
that the significance of the term "channel" may not be
the same as in the case of telephony channels.
On to these digital signal channels CNPU are connected
the various units URB as well as other constituent parts
of the POINTEL network designated by the references CAP,
CEPP and CEDP.
The POINTEL authorization center CAP, manages, for the
whole of the POINTEL network, especially the
subscriptions and thus the authorizations of the POINTEL
- users to call a fixed station SF connected to the
telephony channels CTPU, from an independent station. To
this end, the terminal connecting units URB are linked to
the center CAP by the digital channels CNPU.
- The ~connecting units URB are also linked to the main
POINTEL operation center CEPP, via the digital channels
CNPU, with the aim of transfer of data relating to the
telephony communications exchanged so that the center
CEPP can transmit this data to a billing system.
The decentralized POINTEL operation centers CE~P are
management installations intended to regionally supervise
the operation of the network and especially to detect
anomalies in operation of the connecting units URB and/or
the fixed term;nAls BFR.
It should be noted that the centers CEDP can ct n;cater
by the intermediary o~ the digital channels, data to the
centers CEPP with the aim-of national supervision~
20689~1
When a telephony communication is e~changed between an
independent station SA and a fixed station SF, a radio
frequency link is established between this independent
sta~ion and the fixed terminal BFR whose radio frequency
zone covered by this fixed teL ; n~l contains this
independent station. Moreover, the fixed terminal can be
connected to the public switched telephone network
directly, or also by the intermediary of the connecting
unit URB which manages it, according to the connecting
configuration of the network adopted.
As already mentioned above, when the user carrying the
independent station SA goes out of the zone covered by
the terminal BFR having initialized the radio frequency
link, the telephony co~-ln;cation in progress is broken
off.
The POINTEL network, in its current definition, as well
as the CAI standard, do not -then permit offering this
user the possibility that radio co~ n;cation might be
automatically relayed through a tP ; n~l other than that
which initialized this c~ n; cation.
The main aim of the invention is therefore to remedy this
omission.
To this end, generally, there is provided:
- means of interface with the antennae of a plurality of
fixed terri~s,
- means of connection to the telephony channels of the
network,
specific means, linked to the interface and connection
means, suitable
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20689~1
for establishing a telephony relationship between an
independent station and another station, for example a
fixed station, linked to the telephony channels of the
network, by the intermediary of a primary link between
the independent station and the connection means, via the
antenna of a primary fixed t~rm;n~l,
for establishing at least one secondary link between the
independent station and the said connection means, via
the antenna of a secondary fixed ter~; n~l ~ chosen on the
basis of predetermined selection criteria, and
- station-analysis means, incorporated in the independent
station, suitable for generating a predetermined request
information item relating to the primar~ lin~;
the specific means are thus suitable for responding to
the reception of the said request information item, in
principle in the secondary tPrr;n~l, by switching the
said telèphony relationship so that it passes through
this secondary link.
In order to estahlish thP various links, the interface
mean~ comprise, with respectively the antennae of the
primary and secondary fixed tPr~;n~ls, ~irst primary and
secondary interface stages for a plurality of radio
frequency channels.
It is thus arranged that the specific means comprise:
- primary tPrr; n~l -processing mean~, linked to the said
first primary interface stage of the primary fixed
terminal, suitable for establishing, within the said
primary link, in accordance with the CAI standard, a
primary radio frequency link between the independent
station and the antenna of this fixed terminal, on at
least one of these radio frequency channels.
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20689~1
The primary terminal-processing means thus characterize,
in accordance with the CAI standard, this primary radio
frequency link one-to-one by a link identifier LID1. This
link identifier is different from the identifier LID of
the POINTEL cn~m~ln; cations network which has, for
example, been sent out by the independent station SA when
the user has wanted to be connected to the POINTE~
network with the aim especially of calling another
station. It will be seen later that, according to the
1~ invention, the request information item contains this
link identifier LID1 and that the specific means will use
it in order to reestablish telephone commlln;cation if the
user goes out of the zone of radio coverage of the
primary fixed terminal.
After having extracted this link identifier LIDl, the
primary tP~rm; nal -processing means deliver it to a second
primary interface stage.
The specific means also comprise transfer means, linked
to this second primary interface stage, suitable for
receiving this link identifier LIDl and for c~ n;cating
it to a second secondary interface stage, situated at the
site-~of the secondary fixed terminal. In fact, these
transfer means are suitable for cl- n;cating a link
information item INFL cont~;n;ng, in addition to this
link identifier, other data elements which will be
detailed later.
Finally, secondary tPrmin~l-processing means are
provided, linked to the said first',and second secondary
interface stages and suitable for establishing, within
the secondary link, a secondary radio frequency link
between the independent station and the antenna of this
secondary fixed terminal on at lPast one of these radio
frequency channels with the aid of the said link
identifier LIDl.
2068941
It will ~e seen later that the first and second primary
interface stages, as well as the primary terminal-
processing means are advantageously incorporated in the
primary fixed terminal while the first and second
~ 5 secondary interface stages as well as the secondary
terminal-processing means are incoxporated in the
secondary fixed terminal.
In the same way, the transfer means are preferably
incorporated in the said connecting unit or units
managing the primary and secondary fixed ter~i nal s .
It is possible, as will be seen later, for the primary
fixed tel in~i to be connected to a primary connecting
unit while the secondary fixed terminal is connected to
a separate secondary connecting unit. In this case the
transfer means comprise, within the primary connecting
unit, primary digital interface means linked to the
digital channels of the network and, within the secondary
connecting unit, secondary digital interface means linked
to these same digital channels. The transfer means then
transmit the said link information item INFL cont~in;ng
the link identifier LID1, ~etween the primary and secon-
dary connecting units, by the intermediary of the digital
channels and the primary and secondary digital interface
means.
The primary radio frequency link comprises transmission
of a primary radio frequency signal on at least one of
the radio frequency channels.
The said station condition, in response to which the
station-analysis means will send out the request
information item (link identifier LID1), thus relates to
at least one of the characteristics of this primary radio
frequency signal.
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- 2068941
In accordance with the CAI standard, the primary radio
frequency signal comprises a telephony channel and a
signaling channel. The telephony message, supported by
the primary radio frequency signal, comprises a specific
signaling part (handshake) transported by the signaling
channel, as well as a part, called useful, transported by
the telephony channel. The specific signaling part makes
it possible to check the state of the radio link.
It is then provided that the station-analysis means
analyze the presence of this specific part and carry out
radio frequency transmission of the link identifier LIDl
(request information item) in the absence of this
specific part. This absence may result from exiting from
the zone of radio coverage of the terminal or even poor
radio frequency transmission quality leading to an
incomprehensiDle specific part on the part of the
independent station.
In addition to the means already quoted, the specific
means comprise first analysis means of at least one first
characteristic deduced from this primary radio frequency
signal.
.,
This first characteristic can then consist ln
determination of the level of the said primary radio
frequency signal at the site of the first primary stage
of the primary fixed terminal.
It is also provided that the specific means comprise
second analysis means suitable for ~nalyzing, at the site
of the said first secondary stage, at least one second
characteristic deduced from the primary radio frequency
3Q signal. The criteria of selection of the secondary fixed
t~rm; n~l can then result from analyses of the first and
second analysis means.
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20~894~
The second characteristic is, advantageously,
determination of the level of the radio frequency
- activity on the radio frequency channel of the said first
secondary stage, the counterpart of the radio frequency
channel of the first primary stage on which the said
primary radio frequency signal is tr~nsmitted. This radio
frequency activity then results from the transmission of
this primary radio frequency signal.
In other words, the secondary ter~;n~l or other terminals
lQ can perceive radio frequency activity during transmission
of the primary radio frequency signal between the
independent station and the primary fixed t~rmin~l.
The selection criteria for the secondary fixed terminal
can also comprise, in a variant, reception of the request
information item in this term;n~l.
: It will be seen later that it is possible that the
transfer means will co n;cate the said link information
item INFL to the secondary fixed tPrmin~l, or to all the
teL ;n~ls of the group chosen from terminals adjacent to
the primary fixed t~r~;n~l among which the secondary
term;-n~l is selectable, before reception of the said
request information item.
; It is also pos~ible, in a variant, that these transfer
- means will communicate the link information item INFL to
the secondary fixed terminal after reception of the
request information item.
As far as the connection to the telephony channels of the
network is concerned, it is provided that the connecting
means comprise:
- a first interfaces block linked to the telephony
channels of the network,
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2~6894~
- a second interfaces block linked to some at least of
the fixed terminals of the network, and
- interconnection means between these interfaces.
The specific means thus comprise specific processing
means linked to these interfaces blocks as well as to the
interconnection means.
These specific processing means are then suitable for:
- establishing:
1) a telephony-station link between a first interface
of the first interfaces block and the said other
station, in principle the fixed telephone set,
2) a primary telephony link between a first interface
of the second interfaces block and a third primary
interface stage of the primary fixed tPrr;n~l, and~5 3) a secondary telephony link between a second inter-
face of the second interfaces block and a third
secondary interface stage of the secondary fixed
t~rr;n~l,
- establishing the said telephony relationship by
authorizing interconnection between the first interface
of the first block and the first interface of the second
block, then for
- authorizing interconnection between the said first
interface of the first block and th~ second interface of
the second block in order to switch the said telephony
relationship.
Having now set out the main characteristics of a general
nature of the de~ice according to the invention, refer
ence will now be made to Figures 2 to 6 in order to
illustrate a first configuration of the cl ni cationS
20~8941
network in which at least one specific module UTP is
provided, incorporating at least the first and second
interfaces blocks, the interconnection means and the
specific processing means.
It is provided that the device will comprise a plurality
of specific models assigned respectively to separate
attachment sectors. Figure 2 illustrates, for the sake of
simplification, a single specific module UTP assigned to
an attachment sector.
It will be assumed here that the primary fixed tPrm;nAl
possesses the reference BFR1 while three fixed tPrm; n~l s
adjacent to the terminal BFRl respectively possess the
references BFR2, BFR3 and BFR4. The secondary fixed
terminal which will be chosen is assumed here to be the
terminal BFR2.
It is also assumed that in this configuration the fixed
; terminals of the network are directly connected to the
telephony channels CTPU and that a primary connectin~
unit URB1 manages the fixed terminal BFR1 and BFR3 via
the respective specialized links CCS1 and CCS3 while a
secondary term;n~l connecting unit URB2 manages the fixed
term; n~l s BFR2 and BFR4 via respective specialized links
CCS2 and CCS4.
The first and second interfaces bloc~s, connected to the
. 25 telephony channels CTPU of the network, comprise a
~ plurality of digitising cards for the telephony signals,
bearing the reference as MIC4, ...~. MICll. These cards
are, for example, those marketed by the French company
AETA under reference ES0290.
The interconnection means are here represented by two
digital linking buses BMIC3 and BMIC4 between the various
cards MICj.
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2068941
Each bus BMICj has a capacity of two megabits per second.
A card SIGM analyzes the telephone numbers received from
the telephony channels CTPU at the start of
Cl_ n; cation. The person skilled in the art knows how
to produce such a card, for example using decoders (of
telephone numbers coded according to the CCITT Q-23
standard) such as those marketed by the Brit~sh company
PLESSEY under reference MVa870DP.
A digital interfaces block JONM is also provided, linked
to the digital channels CNPU. This interfaces block here
comprises, for example, a card such as that marketed by
the company MOTOROLA under reference NVME333. It is thus
possible to produce a digital interface conforming to the
international standard CCITT X25.
The specific processing means UCM are linked to the block
J~NM, to the card SIGM and to the cards MICj by a linking
bus BUCM. Physically, the latter can be produced by the
card marketed by the MOTOROLA company under reference
MVME 117A, based on the MOTOROLA 68010 processor
incorporating the software part of these processing
meansU~ with which a dynamic random access memory of 2
megabytes is associated.
Each bus BMICj is suitable for transporting digital data
formed into a,frame subdivided into a pl~rality of time
intervals, typically 32, referenced IT0.. IT31. The first
time interval ITO and the seventeenth time interval IT16
are signaling intervals while the ,other time intervals
' are used for the various telephony channels.
- While the signaling interval ITO is used for the purposes
of synchronization, the sign~ling interval IT16 is used
to attribute a telephone line relating to a call ent~ring
or leaving the module UTP.
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2068941
Thus, the specific processing means are suitable for
acting on this signaling interval ITl6 in order to permit
reception or transmission of a telephone call in or from
the first and second interface blocks MICj.
The module UTP finally comprises supply means ALSM and
ALCM capable of providing voltages of + 5 volts from the
voltage of 48 volts delivered by the switched telephone
network CTPU.
Figure 4 diagrammatically illustrates the bloc~ diagram
of a terri n~l connecting unit URB-i. The suffix i will
be assigned the value 1 when the primary connecting unit
URB1 is concerned, and the value 2 when the secondary
connecting unit URB2 is concerned.
The term; n~l connecting unit URB-i comprises a signaling
unit URBS-i and a switching unit URBC-i as well as power
supply means for these two units~ not shown here t for
reasons of simplification.
The signaling unit URBS-i here incorporates transfer
means while the switching unit URBC-i is not used in this
variant and will be described in more detail later.
The transfer means comprise digital interface means JON-
i linked to the digital channels of the network as well
as to the switching unit URBC-i, and which can be
produced in a manner similar to the digital intPrfaces
bloc~ JONM of the module UTP.
These transfer means also comprise a plurality of inter-
face cards CMBl-i...CMB4-i producing a signaling
interface with the fixed ter~; n~l s BFR. These cards CMB-
i can be, for example, those produced from cards marketed
by the United States company FORCE COMPUTER INC. under
reference SYS68K/ISIO-1/IA, associated with traditional
modems.
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, 20689~1
With these various digital interfaces is associated a
signaling processing unit UCS-i linked to the cards JON-i
and CMB-i by a linking bus BUCS-i. The signaling
processing unit is produced, for example in a way similar
to the specific processing means UCM, based on the
MOTOROLA processor 68010 which incorporates the software
part of the transrer means.
Figures 5 and 6 illustrate a block diagram of the com-
position of a ~ixed term; n~l BFR-i.
The structures of the fixed te ; n~l s BFR o~ the network
are similar. Also, the various constituent parts of this
fixed ter~; n~l have references allocated the suffix j.
This suffix j takes the value l when a so-called
"primary" element is concerned, that is to say associated
with the primary fixed terminal, and the value 2 when a
so-called "secondary" element is concerned, allocated to
the secondary terminal.
In the rest o~ the text, the adjectives primary and
secondary may sometimes be suppressed and understood, for
reasons of simplification.
The primary and secondary fixed terminals BFRl and ~FR2
respectively incorporate the primary and secondary
terminal-processing means, the first primary and
secondary interface stages ETl-l and ETl-2, the second
primary and secondary interfaces stages MOD-l and MOD-2
as well as the third primary and secondary interfaces
stages IRC-l and IRC-2.
The fixed term; n~l BFR-j comprises a power supply block
ALIM-j delivering the voltages plus and minus 5 volts
from an input voltage of 220 volts AC. A ter~; n~l -
processing unit UCB-j is also provided, which can be
produced in any way similar to the signaling processing
unitO
.
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2~68941
The second interface stage MOD-; is, for e~ample,
produced Erom a card similar to that used for the cards
CMB-j. This card makes possible the signaling link
interface with the corresponding term;n~l connecting unit
URB-j.
A radio frequency module RF-j is linked to a third
interface stage IRC-j as well as to the terminal-
processing unit UCB-j and to the antenna ANT-j of the
terminal BFR-j.
The card IRC-j comprises a module for digital interface
with the module RF-j, followed by a digitallanalog and
analog/digital converter block produced, for example, on
the basis of components such as those marketed by the
company SGS-THOMSON under reference ETC 5067. This
converter block is itself followed by a model for analog
subscriber line interface with the channels CTPU in
accordanc~ with the specifications for connection to the
switched telephone network.
Finally, a link bus BUC-j makes it possible to link the
various components of this network together.
~,
As illustrated in Figure 6, the module RF-j comprises a
- frequency changer stage FT-j linked to the antenna ANT-
j, followed by a signal demodulation circuit ~MD-j then
by a signal decoder circuit DCD-j.
This decoder DCD-j is suitable for discriminating on the
one hand the signaling signals cl~ n; cated by a link
SIGN-j to a processing block MPT-j, and word signals
c~mnnicated by another link PAR-j to a block PHO-j
forming the interface with the card IRC-j.
The processing block ~PT-j is linked to the terminal-
processing unit UCB-j as well as to a synthesizer SYN-
~connected, moreover, to the frequency changer stage FT-j
- 20 -
2~6~94~
for selection of the radio frequency channel on which the
radio frequency link is established.
Such a module RF-j is, for example, that currently
available from the Applicant under reference DTRF GPT-
FT equipment.
It can ~e considered, functionally, that the firstinterface stage ET1-j encompasses the two frequency
changer stages, the demodulation and decoding ci~cuits
for the signals as well as the synthesizer.
The term;n~l-processing means as well as the first and
second analysis means comprise software modules incor-
porated within the blocks UCB-j and MPT-j.
We will now consider the case of a telephony co~ n;ca-
tion established from the independent station SA with the
fixed station SF.
When the user is connected to the POINTEL network, by
using the keypad of his handset, the station-analysis
means cl n; cate, for the attention of the fixed
term nal BFRl, which here will be assumed to be the
primary fixed terminal, the identifier LID of the POINTEL
network, as well as the identi~ier PID of the portable
handset. The telephone call coming from the portable
handset SA can be taken into account by the fixed ter-
minal BFR1 since the primary terminal-processing means of
the latter already know the identifier LID of the POINTEL
network. The telephone number of th~ called station, also
composed on the keypad of the handset, as well as the
identifier PID of this portable handset are transmitted
by the intermediary of the primary connecting unit URBl
and digital channels of the network to the POINTEL
authori2ation centPr CAP for checking.
,
2~8941
When this checking is carried out, the transfer means of
the primary connecting unit URBl establish a digital link
with the specific module UTP by the intermediary of the
digital channels of the network. This digital link has
the aim of requesting ~rom the specific processing means
of the module UTP a call number of this specific module
UTP by the intermediary of the switched telephone network
CTPU. This telephony call number is referenced ABPQMCDU.
This call number ABPQMCDU is associated one-to-one with
the identifier PID of the independent station and is
cn~ ln; cated to the connecting unit URBl, returning via
the diqital channels of the network.
The transfer means of the unit URBl then comm~ln;cate via
the signaling line of the specialized link CCSl the call
number ABPQMCDU as well as the authorization from the
POINTEL authorization center CAP, to the primary
terminal-processing means of the tPrmi n~l BFRl.
The primary radio frequency link is thus maintained
between the portable handset SA and this fix~d terminal
and is characterized as quoted above by the link
identifier LIDl, associated one-tO-Qne with this link,
and differing from the network identifier LID.
The primary terminal-processing means then cr ni cate
to the connecting unit URBl this link identifier LIDl.
The transfer means of this connecting unit then broad-
cast, by the intermediary of these digital channels of
the network and the specialized .links to all the
terminals BFR2, BFR3, BFR4 adjacent to the t~rmin~l BFRl,
the link identifier INFL, containing the identifier LIDl,
as well as the call number ABPQMCDU of the specific
module and the identifier of the independent handset PID.
Let us now return to the establishment of the primary
link between the termin~l BFRl and the fixed station SF.
- 22 -
:.
,
20689~
The primary terminal-processing means call the specific
module UTP by the intermediary of the switched telephone
network CTPU, with the aid of the call number A~PQMCDU.
In fact, only the MCDU part of this call number i5
analyzed and used by the module UTP.
This "half-call" from the fixed terminal BFRl to the
specific module is received in the first interface of the
second interfaces block of this module and will con-
tribute to the establishment of the said primary
telephony link.
The specific processing means of the mcdule UTP then
allocate, by the intermediary of the bus BMIC-j, the
first interface of the first interfaces block so as to
reserve a telephony line for the second "hal~-call" from
the specific module UTP to the station SF, which will
contribute to the establishment of the said telephony-
station link.
When this allocation is carried out, the switched tele-
phone network sends, by the intermediary of the specific
processing means of the module UTP, a call tone to the
primary term; n~l -processing means of the terminal BFRl,
and bring about interconnection between the first
interfaces of the first and second interfaces blocks of
the connection means.
The primary terminal-processing means then dial the
telephone number of the called station SF which will have
the consequence of putting the station SA in
co -~;cation with this station SF.
In the course of the telephony c~ n; cation~ when, for
example, the user moves and exits the zone of radio
coverage o~ the term; n~l BFRl, or else if there is any
radio interference, the station-processing means of the
handset will detect the lowering in level of the primary
~068941
radio frequency signal, especially when the latter no
longer receives the specific part of the telephony
message (thus the said predetermined station condition is
present here).
In this case, the station-processing means will
broadcast, on the various radio channels, the request
information item, that is to say the link identifier
LIDl.
All the fixed tPrmi n~l S BFR2, BFR3 and BFR4, adjacent to
the terminal BFR1, are able to recogni~e the link
identifier LIDl since their respective terminal-
processing means have had foreknowledge of it.
It will be assumed, now that the user has approached
terminal BFR2, that it is this latter terminal which
receives the identifier LIDl and which is therefore
chosen among the group of adjacent te i n~l S to be the
secondary fixed tPrr; n~l,
On reception of this link identifier ~IDl, the secondary
tPrm;n~l-processing means of the secondary fixed terminal
are s~itable for sending a secondary call signal to the
said second interface of the second block, with the aid
of the call number ABPQMCDU of the specific module, which
will contribute to the establishment of the said
secondary telephony link. In practice, only the part MCDU
of this call number is transmitted by the switched
telephone network CTPU to the module UTP.
On reception of this secondary call signal at the second
interface of the second interfaces block of th~ specific
module UTP, the specific processing means cause the
interconnection between the first interface of the first
interfaces block and this second interface. The telephony
relationship between the independent station SA and the
fixed station SF is thus switched and the user is offered
.
- 24 -
2~89~1
continuity of service.
In order to prevent untimely switching between two
primary terminals, and in order to possibly leave time
for the primary ~ixed terminal BFRl to pick up an
interrupted radio frequency link again, especially in the
case where an independent handset finds itself
equidistant from two fixed termin~ls, it is preferable
for the secondary terminal-processing means of the
secondary fixed tR i n~l BFR~ only to transmit the said
secondary call signal after a predetermined time delay
typically of the order of 3 seconds, starting on first
reception of the said link identifier LID1 at the said
first secondary stage of this secondary fixed terminal
BFR2. It will be recalled, in fact, that the station-
processing means are able to send out the link identifierat regular intervals until the latter is received by one
of the fixed ~eL inAls.
We will now consider the case where the fixed station SF
wishes to establish telephony cl nication with the
independent station SA.
In order that the independent handset SA can be called,
at no matter what geographical location, it is appropri-
ate that it can be located with re pect to a chosen fixed
terminal. This location information i5 stored in means
forming a data base BDP a~sociated with each specific
module UTP and contained, for P~mple~ in the 2 megabytes
dynamic-random-access memory of the MOTORO~A 68010
processor. This data base BDP comp~ises, in addition to
the location information of the chosen fixed terminal,
here terminal BFRl, and therefore of the independent
station SA, the correspondence between the call number of
this handset SA and its physical identifier PID.
This location information results from a locating
dialogue between the independent handset SA and the
25 -
- 20~89~
chosen terminal BFR1.
The Applicant currently prefers to contemplate the
principle of voluntary location on behalf of a subscribe~
wishing to receive tele.phone calls on his independent
handset. It is assumed that this is the case here for the
user carrying this independent station SA. This wish is
recorded in the database BDP associated with the module
UTP. It is also possible to associate with this wish a
m~;mll~ duration during which the subscriber effectively
wishes to receive telephone calls. A callable independent
station will thus be equipped with means suitable ~or
signifying refusal or acceptance to recei~e telephone
calls. Such an autonomous station can thus effecti~ely
display its intention to receive calls.
The locating dialog can then in this case be the sending
of a locating signal by this handset from the independent
station SA to the chosen fixed terminal BFRl. This can
also be a telephony c~ n; cation (incoming or outgoing)
between this handset and this chosen terminal.
In practice, the database BDP stores, corresponding with
the call number of the independent handset, the digital
identification (for example the address), on the digital
channels, of the connecting unit of terminals URBl having
carried out the last location on the basis o~ a location
signal sent out by the handset, as well as a designation,
for example the number, of the chosen fixed tPrm;n~l BFRl
where this last location took place. Each data base BDP
(here associated with a module UTP) possesses an address
making it possible to contact it on the digital channels
CNPU.
In response to a telephone call request from a calling
fixed station SF on the switched telephone network CTPU,
the specific processing means of the module UTP will
establish a control link with the chosen fixed teL ; n~l ~
2~689~1
This control link comprises, after consultation of the
corresponding data base BDP, a digital link between the
module UTP and the terminal connecting unit URBl whose
address corresponds to the location information item.
More precisely, establishment of this control link
comprises sending a digital signal from the specific
module UTP to the chosén terminal BFR1 by the
intermediary of its connecting unit URB1. This digital
signal comprises, in addition to identification of the
term;n~l BFRl, an ~nstruction for a radio call by this
tPrm;n~l BFRl to the independent station ~A, as well as
the telephone number ABPQMCDU for a call by this tçrm;n~l
BFR1 to the specific module UTP.
This telephone call from the terminal BFRl to the
specific processing means of the module UTP is subject
to the satisfaction of additional ' predetermined
conditions.
A first additional predeterminad condition can be
checking the effective capacity of the fixed term; n~l
BFRl to interact with the handset. This checking can
include, for example, monitoring the correct operation
of this term; n~l or even its capacity to reach the
independent handset SA by radio waves.
Another additional predetermined condition may also be
checking the effective presence of the subscriber ready
to accept the telephone call.
Moreover, the telephony-station link!has been established
between the fixed station SF and the first interface of
the first interfaces block of the module UTP.
When the t~rmi n~l BFRl has called the module UTP for
establishment of the said primary telephony link, this
call being received at the first interface o~ th~ secon~
interfaces block, the specific processing means cause
- 27 -
2~68~41
interconnection of these two interfaces in order to
establish the telephony relationship.
As before, in parallel with this establishment, the
transfer means co~m-ln;cate to the terrin~ls BFR2, BE'R3
and BFR4 adjacent to the terminal BFRl the link
identifier LIDl as well as the call number ABPQMCDU of
the module UTP so that this telephony relationship can
possibly be switched by passing through a terminal
adjacent to the tPrr;n~l BFRl.
It is appropriate also to note that, when the inter-
connection is effectively set up within the specific
module UTP, the primary and possibly secondary telephony
links between the independent station and the specific
module are recorded as being charg~d to the subscriber
holding the independent handset in order to bill him as
a consequence. The telephony station link established
between the fixed station and the module UTP is recorded
as being charged to the ~ixed station with a view to
billing it.
- 20 In the case of a telephone call coming from the indepen-
dent-~station to the fixed station all the telephony links
established are charged to the caller.
We will refer now to ~igure 7 which illust~ates a second
configuration of the network in which specific modules
UTP are not provided. In contrast, the first and second
interfaces blocks, the interconnection means and the
specific processing means are incor~orated into at least
some of the connecting units of the network~ in practice
into all the connecting units. The other means of the
device according to the invention remain, in this
variant, installed as described a~ove.
We also assume here that the ~ixed tPrm; n~ 1 S are not
directly connect~d to the telephony channels of the
- 28 -
206894.1
~ network CTPU but by the intermediary of their respective
connecting unit.
For the sake of simplicity in the description ik will
also be assumed here that the primary and secondary fixed
terminals BFRl and BFR2 are both connected by respective
specialized links CCSl and CCS2 to the connecting unit
URBl.
If we return now to Figure 4, it will be noted that the
switching unit URBC-j of the connecting unit URB-j (here
URBl) comprises, in addition to the plurality of cards
MIC-j, MIC-2 for digitising the telephony signals,
forming the first interfaces block, a plurality of
specialized acoustic interfaces cards IAPl...IAP4
suitable for being connected to the primary and secondary
fixed terminals via the specialized links CCSl and CCS2.
These cards IAPj comprise an interface with linking buses
BMICS and BMIC6, followed by a converter block similar to
that used in the card IRC-j, followed in turn by a
telephony interface (limited to the acoustic part) on a
specialized link with the tPrm; ~Al S .
The first interfaces block also comprises a plurality o~
cards ILA1, ILA2 suitable for producing an interface for
connecting to telephony channels CTPR of a private
cl- nications network.
These cards exhibit a structure similar to the cards
IAPj, the telephony interface over a specialized link
being replaced by an analog subscriber line interface
with the channels CTPR in accordance with the
specifications for connection to the switched telephone
network.
.
All of these cards are linked together by linking buses
BMI~5 and BMIC6 as well as to a switching processing unit
- 29 -
.
20~9~
uCc-i linked to the signaling processing unit UCS-j.
This switching processing unit is, for example, produced
with the aid of the MVME 117A card (already quoted),
incorporating one of the software parts of the specific
processing means.
When, in the case of a telephony co~ n;cation
established from the independent station SA to the fi~ed
station SF, the user dials the telephone number of this
fixed station, on the keypad of his handset SA, the
checking procedure is carried out in liaison ~ith the
center CAP, in a similar way to that described aboveO
Wh~n authorization is granted by the center CAP, the
primary radio frequency link is maintained between the
portable handset SA and the fixed tPr~;n~l and is charac-
terized in a way similar to that quoted above by the linkidentifier LID1.
The specific processing means of the connecting unit URB1
then allocate, by the intermediary of the buses BMlC, the
first interface of the first interfaces block so as to
reserve a telephone line for the half-call from the
conn~cting unit to the station SF, so as to contribute to
the establishment of the said telephony-station link.
In parallel, the specific processin~ means allocate, by
the intP ?~;ary of the cards IAP-j, the first interface
of the second interfaces block contributing to the
establishment of the primary telephony link.
I
When these allocations are carried out, the specific
processing means transmit, by the intermediary of a card
CMB-j and of the signaling path of the spPcialized link
CCSl, a call tone sent out by the chanr.els CTPU, to the
primary tPrr;n~l-processing means of the tPrr;n~l BFRl,
and cause interconnection between the first interfaces of
the first and second interfaces blocks.
- 30 -
2~G~9~
The primary terminal-processing means then dial the
telephone number of the called station SF, which will
have the consequence of putting the station SA in
communication with the station SF.
In the course of the telephony c-- n; cation, the first
and second analysis means, here formed by software
modules incorporated within the terminal connecting unit
URBl, analy~e respectively the level of the primary radio
frequency signal exchanged between the independent set
and the first interface stage of the primary tP ; n~l
BFRl, and the level of the radio frequency activity,
resulting from the transmission of the primary radio
frequency signal, on the radio frequency channels of the
neighboring te ; n~ 1 s ~ the counterparts of the radio
frequency channel of the first primary stage on which the
said primary radio frequency signal is transmitted.
Needless to say that assumes that at least one of the
neighboring ter~; n~l s is not saturated, that is to say
that all its radio channels are not already used for
other radio frequency links with other independent
stations.
.,
When the level of the primary radio signal crosses a
predetermined threshold, for example becomes less than
-80 dBm, and when, in parallel, the level of the radio
frequency activity on one of the neighboring terminals
becomes greater than another predetermined threshold, for
example of the order of -60 dBm, this ter~;n~l (assumed
to be the t~rm; nal BFR2) will be selected in order to
switch the telephony relationship in progress.
In order to do that, the transfer means will then commu-
nicate to this ter~; n~l BFR2 the link identifier LID1.
The specific processing means will then allocate, b~ the
interm~ ry of a card IAP-j, an acoustic link between
this terminal BFR2 and the terminal connecting unit.
- 31
-t
2~68941
On reception of the link identifier LIDl sent out by the
independent station, a channel will be selected on which
the secondary radio frequency link will be established,
and the specific processing means will break off the
acoustic link between the first interface of the second
interfaces block (at the site of a card IAP-j) and the
primary terminal BFRl, then will carry out
interconnection between the second interface of this
second interfaces block and the first interfaces of the
first interfaces block produced at the fixed station SF.
In order to avoid the term; n~l BFRl taking up the radio
link again (since it also receives the identifier 1IDl
sent out by the portable handset) so as to immediately
generate a new switch to teL ;nAl BFR2, it can be
provided for a signal to be sent to a terminal BFRl
forbidding it to recognize the identifiex LIDl. Thus,
only terminal BFR2 will be able to pick up the radio
link.
For the user, switching this telephony relationship is
perceived as reestablishment of the radio link. It will
also be noted that the outgoing path is, on the contrary,
not ~hanged. There is thus no break in the telephony-
station link to the fixed station SF.
It ha~ been assumed here that the link identifier LIDl
was co nicated to the secondary fixed terminal after
the analysis carried out by the first and second analysis
means. It could also be envisaged that, in parallel with
the establishment of the primary li~k passing through the
primary fixed terminal, the term;nAl connecting unit is
already broadcasting the link identifier LIDl to the
other neigh~oring terminals, that is to say before
choosing a secondary fixed term; n~ 1 .
The invention also permits ensuring continuity of
service, not only when the user moves, but also when the
- 32 -
20~8~41
external environment disturbs the radio link with the
terminal, by choosing another less "disturbed" terminal,
and to do this on the initiative of the independent
station.
The invention is not limited to the embodiments described
above but embraces all the variants contained in the
scope of the claims below, especially the following:
- the two embodiments described, based on specific
modules and without specific modules, are not incom-
patible. In this context a network configuration couldbe envisaged in which some geographical sectors might be
equipped with specific modules and other geographical
sections would contain the specific means incorporated in
the terminal connector units;
- the specific module UTP, or even a connecting unit,
could equally be connected to a private co n; cations
network also cont~in;ng private telephony channels and
private digital channels;
- it is also not excluded that the use could be
envi~aged, in the second variant described, of the type
of predetermined conditions and/or selection criteria
used in the first variant, and conversely;
- it i~ also pos~ible to include, within the module UTP
or a connecting unit, a card making it possible to send
out recorded standby messages to the calling users. This
card could be equipped with voice synthe~is genera~ors
associated with memories~
- Telephone calls originating from a calling independent
station to a callable independent station could certainly
be envisaged. In this case, one of the fixed terminals
interacting with one of the independent calling or called
stations plays the role of the fixed station SF described
20689~1
above.
- More generally, an independent station is not limited
to a telephony handset but relates to any object capable
of interacting with a fixed terminal.
Needless to say, some of the means described above can
be omitted in the variants where they have no function.
- 34 -
'
