U.S. patent application number 11/617653 was filed with the patent office on 2007-05-10 for communications network, in particular for telephony.
Invention is credited to Andrea Casini, Pier Faccin.
Application Number | 20070105560 11/617653 |
Document ID | / |
Family ID | 11438824 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070105560 |
Kind Code |
A1 |
Casini; Andrea ; et
al. |
May 10, 2007 |
COMMUNICATIONS NETWORK, IN PARTICULAR FOR TELEPHONY
Abstract
A communications network, in particular for telephony, comprises
at least one operator, a plurality of remote units for exchanging
signals with mobile terminals and an interface unit for controlling
the data traffic between the operator and the remote units. The
interface unit is connected to the remote units by a first
transmission support, in which the main signal propagates. The main
signal is divided into a plurality of secondary signals, each
identified by a preset parameter value. Each remote unit is
designed to process at least one secondary signal selected from
amongst the secondary signals into which the main signal is
divided. The secondary signal is identified by the remote unit
according to the above-mentioned preset parameter value.
Inventors: |
Casini; Andrea; (Faenza,
IT) ; Faccin; Pier; (Savignano Sul Rubicone,
IT) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH LLP
Two Prudential Plaza
180 North Stetson Avenue, Suite 2000
CHICAGO
IL
60601
US
|
Family ID: |
11438824 |
Appl. No.: |
11/617653 |
Filed: |
December 28, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10088123 |
Mar 14, 2002 |
7158789 |
|
|
PCT/IB01/02040 |
Oct 30, 2001 |
|
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11617653 |
Dec 28, 2006 |
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Current U.S.
Class: |
455/446 |
Current CPC
Class: |
H04B 10/25753 20130101;
H04B 10/25752 20130101 |
Class at
Publication: |
455/446 |
International
Class: |
H04Q 7/20 20060101
H04Q007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 31, 2000 |
IT |
BO2000A000634 |
Claims
1. A communications network, in particular for telephony,
comprising: at least one operator; a plurality of remote units
designed to exchange signals with the operator and to exchange
radio frequency (RF) signals with mobile terminals; an interface
unit inserted between the operator and the remote units, the
interface unit having at least one input for receiving signals from
the remote units and at least one output for sending signals to the
remote units, the interface unit also being designed to exchange
signals with the operator; a first transmission support for
connecting the interface unit to the remote units, the first
transmission support being designed to support a main signal, the
first transmission support having a first end connected to the
interface unit input and at least a second end connected to the
interface unit output, the main signal consisting of a plurality of
secondary signals, each identified by a preset parameter value,
each of the remote units receiving said main signal and being
designed to process a secondary signal intended for it, each of the
remote unites being able to select at least one secondary signal
intended for it from said main signal according to the preset
parameter value.
2. The network according to claim 1, wherein the preset parameter
is a wavelength, the remote units sending to and receiving from the
interface unit signals at the wavelength (.lamda.i) associated with
them.
3. The network according to claim 1, wherein the secondary signals
received from and sent to the interface unit by the remote units
are bundled and preferably multiplexed by the interface unit
according to the dense wave division multiplexing (D-WDM)
technique.
4. The network according to claim 1, wherein the first transmission
support comprises an optic fibre support, the main signal being an
optical signal propagating from the second end to the first
end.
5. The network according to claim 1, wherein each remote unit
comprises: a signal transmission block connected to the first
transmission support for picking up at least one secondary signal
from the main signal to be transmitted in the DL; a signal
reception block connected to the first transmission support for
adding at least one signal received in the UL to the main signal;
an antenna attached to the signal transmission block and to the
signal reception block for transmitting RF signals to the mobile
terminals and for receiving RF signals from the mobile
terminals.
6. The network according to claim 1, wherein the interface unit
comprises: a signal transmission circuit connected to the output
and connected to the second end of the first transmission support,
the signal transmission circuit picking up signals from the
operator and sending them to the remote units; a signal reception
circuit connected to the input and connected to the first end of
the first transmission support, the signal reception circuit
receiving signals from the remote units and transmitting them to
the operator.
7. The network according to claim 6, wherein the signal
transmission circuit comprises: a first routing matrix with at
least one input connected to the operator for receiving a signal
from the operator and two or more outputs for sending electrical
signals; a first electro-optical converter unit connected to the
outputs of the first routing matrix, for transforming the
electrical signals from the first routing matrix into optical
signals; a multiplexer between the first electro-optical converter
unit and the second end of the first transmission support, for
bundling and transferring the optical signals from the first
electro-optical converter unit in the first transm
8. The network according to claim 6, wherein the signal reception
circuit comprises: a demultiplexer connected to the first end of
the first transmission support, for receiving the main signal and
having a plurality of outputs for sending optical signals; a second
electro-optical converter unit connected to the outputs of the
demultiplexer for transforming the optical signals sent by the
demultiplexer into electrical signals; a second routing matrix with
two or more inputs connected to the second electro-optical
converter unit and at least one output connected to the
operator.
9. A communications network, comprising: at least one operator; a
first remote unit and at least a second remote unit, the remote
units being designed to exchange signals with the operator and to
exchange radio frequency (RF) signals with the mobile terminals; an
interface unit inserted between the operator and the remote units,
the interface unit having at least one input for receiving signals
from the remote units and at least one output for sending signals
to the remote units, the interface unit also being designed to
exchange signals with the operator; a first transmission support
for connecting the interface unit to the remote units , the first
transmission support being designed to support a main signal, the
first transmission support having a first end connected to the
interface unit input and at least a second end connected to the
interface unit outputwherein the first remote unit has a first
input directly connected to the interface unit output by the first
transmission support and a first output, the second remote unit
having a first input connected to the first output of the first
remote unit by the first transmission support and a first output
directly connected to the interface unit input by the first
transmission support, the main signal propagating in the first
transmission support from the second end to the first end.
10. The network according to claim 9, wherein the first
transmission support basically consists of an optic fibre loop
passing through each remote unit, the main signal being an optical
signal propagating in the loop from the first remote unit to the
second remote unit.
11. The network according to claim 1, further comprising a
plurality of operators which can be connected to the remote units
by means of the interface unit.
12. The network according to claim 9, further comprising a
plurality of operators which can be connected to the remote units
by means of the interface unit.
13. The network of claim 1, wherein a first remote unit has a first
input directly connected to the interface unit output by the first
transmission support and a first output, a second remote unit
having a first input connected to the first output of the first
remote unit by the first transmission support and a first output
directly connected to the interface unit input by the first
transmission support, the main signal propagating in the first
transmission support from the second end to the first end.
14. The network of claim 13, wherein the first transmission support
comprises an optic fibre loop passing through each remote unit, the
main signal being an optical signal propagating in the loop from
the first remote unit to the second remote unit.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/088,123, filed Mar. 14, 2002, which claims
the benefit of International Patent Application No. PCT/IB01/2040,
filed Oct. 30, 2001, which claims priority of Italian Patent
Application No. B02000A000634, filed Oct. 31, 2000.
TECHNICAL FIELD
[0002] The present invention relates to a communications network,
in particular for telephony.
BACKGROUND ART
[0003] As is known, at present in the communications systems for
cellular telephony the mobile terminals (cellular phones) dialog by
means of radio frequencies with the Base Station Systems,
hereinafter referred to with the abbreviation BSS (Base Station
System), which are connected to the Control Centres, hereinafter
referred to with the abbreviation MSC (Mobile Services Switching
Centre). The latter allow a connection both to other MSCs,
therefore to other mobile phones, and to the fixed network.
[0004] The BSSs and MSCs are fixed units and can be connected using
optic fibre or with conventional electric cables.
[0005] Each BSS consists of a Controller, hereinafter referred to
with the abbreviation BSC (Base Station Controller), connected to a
plurality of transceivers, hereinafter referred to with the
abbreviation BTS (Base Transceiver Station), which basically form
the terminals of the fixed part of the network which controls
communication between mobile phones.
[0006] In order to improve the quality of the signal and cover the
widest possible areas, the BTSs are placed in strategic positions,
in particular in high places, for example on the top of
particularly tall buildings.
[0007] With the introduction of third generation (UMTS, Universal
Mobile Telecommunications System) mobile phones, this is no longer
possible, since the structure of the new base stations is much more
bulky and heavy and, as a result, much more difficult to handle
from a logistics viewpoint. It is easy to imagine how positioning
it on a roof, for example, could be extremely problematic.
[0008] Therefore, a slight variation of the conventional structure
of the BSSs became necessary, disconnecting the BTSs from the
antennas and inserting interface units to control the
communications traffic between the BTSs and the remote units
(RU--the terminals which comprise the antennas for
sending/receiving radio frequency signals to/from mobile
phones).
[0009] The second section of the connection between the BTSs and
RUs, from the interface to the RUs, is normally created using optic
fibre with significant advantages in terms of the quality of the
communication (low attenuation) and the speed of data
transmission.
[0010] The data exchange between BTSs and RUs must occur in both
directions. The data from the BTSs to the RUs and, as a result, to
the mobile phones, is the Down-Link (DL), whilst the signals from
the mobile phones received by the RUs and sent on to the BTSs are
the Up-Link (UL).
[0011] Two different wavelengths are normally used for the
above-mentioned data exchange, one for the DL and one for the
UL.
[0012] A typical example of the connection between the base
stations and remote units is the so-called "backbone "
configuration. An optic fibre cable runs fromt he interface unit to
all of the RUs and ends close to the last RU. Each RU picks up a
portion of the signal present in the fibre selects the DL
wavelength, transforms the optical signal into an RF signal and
sends it to the mobile phone by means of an antenna. In parallel,
if the RU must send data to the BTS, it sends a UL signal at a
preset wavelength, different to that of the DL, in the optic
fibre.
[0013] In this way, there are two data flows supported by the optic
fibre, one from the interface unit to the RUs (DL) and one, in the
opposite direction to the first, from the RUs to the interface unit
(UL).
[0014] The UL and DL can be provided using two physically different
supports (one fibre for the DL and another fibre for the UL),
without significantly altering the structure and operation of the
above-mentioned configuration.
[0015] The main disadvantage of this type of connection between the
BTSs and RUs is the excessive waste of band in order to set up a
bi-directional connection. The connection for each RU uses double
the band actually occupied by the signals to be
transmitted/received. Too much optic fibre is also used, with
significant economic effects on the set up of current systems based
on state of the art structures.
SUMMARY
[0016] The aim of the present invention is to provide a new
communications network, in particular for telephony, which allows
maximum use to be made of the available band when
transmitting/receiving signals between operators and remote
units.
[0017] Another aim of the present invention is to minimise the
amount of optic fibre used to create the connection between the
operators and the remote units.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Further features and advantages are apparent in the detailed
description below, with reference to the accompanying drawings,
which illustrate a preferred embodiment of a communications
network, in particular for telephony, without limiting the scope of
its application, and in which:
[0019] FIG. 1 is a block diagram of a communications network in
accordance with the present invention;
[0020] FIG. 2 illustrates the structure of some of the blocks in
FIG. 1;
[0021] FIG. 3 is a schematic illustration of the structure of a
signal processed by the network in FIG. 1.
DETAILED DESCRIPTION
[0022] A communications network, in particular for telephony, is
labelled with the numeral 1 in the accompanying drawings.
[0023] The network 1 basically consists of an operator 2 (a unit
controlled by a telecom company, which allows connection to the
rest of the telephone network, both mobile and fixed) and a first
remote unit 3 and at least a second remote unit 4, which use
antennas and suitable circuit equipment to allow signals to be
exchanged between the operator 2 and the mobile terminals 5.
Between the operator 2 and the remote units 3, 4 there is an
interface unit 6, designed to control the data traffic between the
operator 2 and the remote units 3, 4.
[0024] The network 1 may comprise two or more operators, that is to
say, a plurality of blocks controlled by different telephone
companies for connection to the rest of the telephone network. In
this case, the interface unit 6 controls access to the remote units
3, 4 depending on the requirements of each operator.
[0025] Advantageously, each operator 2 communicates with the
interface unit 6 by transmission and reception using two carriers,
each having a separate physical support.
[0026] The interface unit 6 is connected to the remote units 3, 4
using a first transmission support 9, preferably consisting of
optic fibre, with at least a first end 10 connected to an interface
unit 6 input 7, and at least a second end 1 1 connected to an
interface unit 6 output 8. In this way, the remote units 3, 4 can
send/receive signals to/from the interface unit 6 and, as a result,
a bi-directional data flow is possible between the remote units 3,
4 and the operator 2.
[0027] As illustrated in FIG. 1, the interface unit 6 consists of a
signal transmission circuit 25 and a signal reception circuit
26.
[0028] The signal transmission circuit 25 is positioned at the
interface unit 6 output 8 and is connected to the second end 11 of
the first transmission support 9. It is basically designed to pick
up the signals from the operator 2 and send them to the remote
units 3, 4 using the first transmission support 9. The signal
transmission circuit 25 is made with a first routing matrix 27, a
first electro-optical converter unit 28 and a multiplexer 29. The
first routing matrix 27 has at least one input connected to the
operator 2 and a plurality of outputs, each connected to a remote
unit. The first routing matrix 27 is designed to route the signals
from the operator 2 to the remote units 3, 4 pre-selected by the
operator 2.
[0029] The electrical signals at the first routing matrix 27
outputs are converted into optical signals by the first
electro-optical converter unit 28, so that they can then be sent
using an optic fibre support. Finally, the multiplexer 29
downstream of the converters 28, bundles and transfers all optical
signals in a single physical support, that is to say, the first
transmission support 9.
[0030] Therefore, inside the first transmission support 9, a main
signal 44 is transmitted, containing all of the data to be sent
from the operator 2 to the remote units 3, 4 and vice versa, the
data to be sent from the remote units 3, 4 to the operator 2.
[0031] FIG. 3 shows how the main signal 44, propagating in the
first transmission support 9, consists of a plurality of secondary
signals 45 identified by a preset parameter value characteristic of
the main signal 44. Advantageously, said parameter may be the
wavelength and each secondary signal 45 is, therefore, identified
by its own wavelength .lamda.i, .lamda.i+1, .lamda.+2, etc.
[0032] Conveniently, to optimise use of the optic fibre, that is to
say, to maximise the number of carriers supported by the fibre, the
wave division multiplexing (WDM) technique is used, which consists
in sending data along the same fibre, using two or more signals
with different wavelengths.
[0033] In particular, dense wave division multiplexing (D-WDM) is
used, fixing the separation of the signal wavelengths propagating
in the optic fibre in the 0.5-5 nm range.
[0034] Advantageously, semi-dense wave division multiplexing
(SD-WDM) can also be used, in which special lasers modulate the
signals, which are propagated at the third window of the optic
fibre (propagation in an optic fibre occurs in three wavelength
ranges, called "windows", the third corresponding to wavelengths of
around 1550 nm).
[0035] The signal reception circuit 26 is completely symmetrical
relative to the signal transmission circuit 25 described above. It
has a demultiplexer 30, connected to the first end 10 of the first
transmission support 9, to separate the various secondary signals
45 from the remote units 3, 4 sent to the circuits downstream by
means of a plurality of outputs. The optical signals from the
demultiplexer 30 are then converted into electrical signals by a
second electro-optical converter unit 31, then sent to the operator
2 (or operators) by means of a second routing matrix 32.
[0036] In light of this, it is obvious how the interface unit 6 is
able to control the traffic of signals between the operator 2 (or
operators) and the remote units 3, 4.
[0037] FIG. 2 is a block diagram of a single remote unit. It
comprises a signal transmission block 12, connected to the first
transmission support 9 to pick up at least one secondary signal 45a
from the main signal 44 (the secondary signals 45 are then sent to
the mobile terminals 5 by means of an antenna 14) and a signal
reception block 13, which receives the RF signals from the mobile
terminals 5 by means of the antenna 14 and adds them to the main
signal 44 in the first transmission support 9.
[0038] Conveniently, the signal transmission block 12 is made using
an optical filter element 15 to pick up at least one secondary
signal 45a from the main signal 44, a first electro-optical
converter 17 to transform the secondary signal 45a into an
electrical signal, a first amplifier block 18 and a first RF filter
19 to treat the electrical signal before transmitting it in radio
frequency to the mobile terminals 5 by means of the antenna 14.
[0039] Similarly, the signal reception block 13 comprises a second
RF filter 20 and a second amplifier block 21 for treating the RF
signals arriving from the mobile terminals 5 and received by the
antenna 14, a second electro-optical converter 22 to transform the
electrical signals into optical signals and a signal reception
element 26 connected to the first transmission support 9 to add the
contributions received from the mobile terminals 5 to the main
signal 44.
[0040] Advantageously, to equalise the secondary signal 45a and
prepare it for subsequent processing, the signal transmission block
12 has a first equaliser block 16 downstream of the optical filter
element 15 and the signal reception block 13 has a second equaliser
block 23 downstream of the second electro-optical converter 22.
[0041] The first transmission support 9 is made substantially in
the form of an optic fibre loop which terminates at the interface
unit 6 and passes through all of the remote units 3, 4 once. The
first remote unit 3 has a first input 33 directly connected to the
output 8 of the interface unit 6 and a first output 34 connected to
a first input 35 of the second remote unit 4. The latter has a
first output 36 directly connected to the input 7 of the interface
unit 6.
[0042] Similarly, each remote unit is associated with at least one
wavelength .lamda.i. If necessary a plurality of wavelengths
.lamda.i, .lamda.i+1, etc. can be associated with a single remote
unit.
[0043] In this way, when the operator 2 wants to send a signal to a
given remote unit so that it will be transmitted to a mobile
terminal 5, it uses the first routing matrix 27 and the first
electro-optical converter unit 28 to shift the signal remote unit
and the signal is introduced into the first transmission support 9
by the multiplexer 29.
[0044] Using the circuit equipment described above, the selected
remote unit selects, within the main signal 44, the secondary
signal 45a at the wavelength .lamda.i associated with the remote
unit, converts it to RF and sends it to the mobile terminal 5 to
which the signal is directed.
[0045] When the remote unit receives signals from the mobile
terminal 5 which must be sent to the operator 2, it shifts them to
its characteristic wavelength .lamda.i and inserts them into the
main signal 44, so that at the end of propagation in the first
transmission support 9, they reach the input of the interface unit
6 and, from here, are sent to the operator 2.
[0046] With a structure such as that described above, each remote
unit is, therefore, associated with a wavelength .lamda.i on which
it dialogs in both directions with the interface unit 6 and,
therefore, with the operator 2.
[0047] The fact that the optic fibre support substantially assumes
the form of a loop closed on the interface unit 6 allows the main
signal 44 to be sent from the interface unit 6 output 8, to go
through all of the remote units 3, 4 (transmitting to and receiving
from them any signals at the preset wavelength .lamda.i) and to
reach the interface unit 6 input 7, carrying all of the data
gathered from the remote units 3, 4.
[0048] Advantageously, the network 1 may have a second transmission
support 41, again made of optic fibre and having the twin purposes
of making the system more reliable and improving the quality of
reception and transmission of the mobile units 3, 4 and the
interface unit 6.
[0049] As explained in greater detail below, another advantage of
the second transmission support 41 is that the communications
network 1 created is also resilient.
[0050] The second transmission support 41 is an optic fibre loop
with a first end 42 connected to the interface unit 6 input and a
second end 43 connected to the interface unit 6 output 8. Inside
the second transmission support 41, an auxiliary signal 46
substantially equal to the main signal 44 is propagated.
[0051] The second transmission support 41 passes through all of the
remote units 3, 4 once, so that the auxiliary signal 46 reaches the
remote units 3, 4 in the opposite order to the main signal 44
propagated in the first transmission support 9. The second remote
unit 4 has a second input 39 directly connected to the interface
unit 6 output by means of the second transmission support 41 and an
output connected to a second input 37 of the first remote unit 3 by
means of the second transmission support 41. The first remote unit
3 has a second output 38 directly connected to the interface unit 6
input by means of the second transmission support 41.
[0052] The auxiliary signal 46 is a replica of the main signal 44
and is propagated in the second transmission support 41.
[0053] In this way, by supplying the remote units 3, 4 with the
same data by means of two separate physical supports, there are
significant advantages in terms of the quality of the
communication. If, for example, the first transmission support 9
develops a fault, thanks to the second transmission support 41
there would be no need to interrupt the connection between the
remote units 3, 4 and the interface unit 6.
[0054] Moreover, by constantly using both transmission supports 9,
41, so that the two identical signals 44, 46 are constantly
supplied to each remote unit 3, 4 by means of independent supports,
the probability of reception/transmission errors is reduced, that
is to say, it becomes extremely unlikely that part of the data will
be lost or altered as it travels between the interface unit 6 and
the remote units 3, 4.
[0055] Use of the second transmission support 41 may be controlled
in various ways. The auxiliary signal 46 may be propagated only if
a fault develops in the first transmission support 9, or it may be
constantly propagated parallel with the propagation of the main
signal 44 in the first transmission support 9, to reduce the
probability of error as indicated above.
[0056] If more than two remote units are required, a third remote
unit may, for example, be positioned between the first remote unit
3 and the second remote unit 4.
[0057] The third remote unit would have a first input, connected to
the first output 34 of the first remote unit 3 by the first
transmission support 9, and a first output connected to the first
input 35 of the second remote unit 4. The third remote unit would
also have a second input, connected to the second output 40 of the
second remote unit 4 by the second transmission support 41, and a
second output, connected to the second input 37 of the first remote
unit 3.
[0058] The networks described herein generally provide certain
advantages.
[0059] First, an entire communications network is extremely
economical to set up, since the optic fibre used is minimised.
[0060] Moreover, it is very efficient in terms of band use, since
the same wavelength .lamda.i is used both for the DL and the UL
between the interface unit and the remote units.
[0061] Another advantage is the fact that, thanks to the
versatility of the routing matrices, the network is very flexible
and can be adapted to various requirements when setting up the
connections between the operators and the remote units.
[0062] Finally, the introduction of a second loop, parallel with
and propagating in the opposite direction to the first, allows the
creation of a communications network which is resilient and
characterised by the high quality of the connection between the
operators and the remote units.
[0063] The network and its components described herein may be
subject to modifications and variations without thereby departing
from the claims. Moreover, all the elements of the network and its
components may be substituted with technically equivalent
elements.
* * * * *