Title of Invention

NODE FOR AN OPTICAL COMMUNICATION NETWORK

Abstract A node for an optical communication network comprises at least one switching unit (2), a plurality of optical interfaces (1) for connecting to a WDM transmission line (3), which comprise a demultiplexer (4) for dissassembling a multiplex signal arriving from a WDM transmission line (3) into a plurality of input channels (8), each of which is supplied to an input port of the switching unit (2), and a multiplexer (5) for assembling a plurality of output channels (11), each originating from an-out-put port of the swithching unit (2), into an outgoing multiplex signal, and at least one transponder (6) for adding and information signal to and deopping it from the communiction network, respectively. Input and output branching meand (7) between each interface (1) and the switching unit (2) on the path of the input channel (8) to the switching unit (2) or to the transponder (6), or to supply an output channel (11) form int interface to the switching unit (2) or the transponder (6)
Full Text FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
NODE FOR AN OPTICAL COMMUNICATION NETWORK
MARCONI COMMUNICATIONS GMBH, of Gerberstrasse 33, D-71520 Backnang, Germany
The following specification particularly describes the invention and the manner
in which it is to be performed.
,WO 21**5/112991*5 PC T/EP2WM/052114
In order to achieve as high a degree of reliability as possible in such a network, all
components of the network should be redundant Le., for an information signal which is
transmitted between start and target nodes of the network on a so called working path, at
5 least one protection path must exist, on which path a copy of the information signal is
transmitted, so that in case of a failure of the main path the copy transmitted on the
protection path is available at the target node and can be used, or which path is kept
available for transmitting such a copy in case of need, so that if a failure of the working
path is detected, the transmission may be continued on the protection path with
10 minimum loss of time.
Working path and protection path must go along different transmission lines and, if
available, different intermediate nodes at these transmission fines, so that an interruption
of a single transmission fine or a failure of a single intermediate node cannot cause
working and protection paths to fail at the same time.
Start and target nodes are necessarily the same- for both paths, so that in such a node
special measures have to be taken in order to avoid that a partial failure of such a node
affects both paths simultaneously.
20
Known solutions of this problem will be outlined briefly based on Fig. 1, which shows
schematically a prior art structure of a nod
WO2005/029905
PCT/EP2M4/052114

3
The node comprises a plurality of interfaces 1, two of which are shown in the Figure,
and which connect a central switching unit 2 of the node to bi-directional optical transmission lines 3 attached to the interfaces 1. Each interface 1 comprises a demulti-
plexer 4 having an input connected to the transmission line and a number of outputs
5 according to the number of wavelengths of a multiplex transmitted on the transmission
line 3. The demultiplexer 4 disassembles the multiplex signal into its various modulated carrier waves, each of which correspond to one information signal, and outputs these at one of its output ports. Each of these output ports is connected to an input port of the switching unit 2, which switches the concerned information signal to at least one of its
10 output ports. These output ports are each connected to an input port of a multiplexer 5 which assembles the information signals present at its input ports into an outgoing
multiplex signal, or to a transponder 6. The transponders 6 each comprise an optical-
electrical or an electrical-optical converter which allow a source or sink connected to it,
both of which are referred to as a terminal in the following, to input data into the
15 network or to receive them therefrom. In order to protect the terminal against failures of
the transponders 6, there must be assigned to it a working transponder for conveying the working signal and a protection transponder, which conveys the protection signal or is
adapted to do so in case of need. A protection against failures of the switching unit 2 is
not possible straightforwardly; if it fails, no optical information signal can be trans-
20 mitted anymore between the transmission lines 3 and the transponders 6.

In order to protect against failures of the switching unit 2, it might be duplicated.
However, this solution is extremely expensive.

VV O 2IW5/029W5 PCT/EP2004/052114
4
A possibility to provide redundancy at less expense is to form the switching unit 2 not
as a single switching fabric, the input ports of which are connected to all demultiplexers
4 and transponders 6 and the output ports of which are connected to all multiplexers 5
and transponders 6, but to form the switching unit from a plurality of switching fabrics,
5 each of which receives from each demultiplexer only a specific carrier wavelength
assigned to it and switches it to the multiplexers. If working and protection transponders
of a same terminal are connected to different ones of these wavelength selective
switching fabrics, a failure of a single one of these switching fabrics can no longer
affect working and protection signals simultaneously. However, this solution works
10 only if it is ensured that working and protection signals reach the node not only by different transmission lines, but also with different carrier wavelengths.
If the individual switching fabrics switch not only one but several carrier wavelengths,
the restrictions are still more serious, since the protection signal, in order to make sure
15 that it is conveyed by another switching fabric than the working signal, must not have
any of the several carrier wavelengths which are switched by the switching fabric that conveys the working signal.
The object of the invention is to provide a node for an optical communication network
20 which is simple and economic to manufacture and which has no components which are passed through both by a working signal and by its associated protection signal, so that a failure of this component might interrupt both signals.

' WO 2»M>5/02VW5 PCT/EP2IMM/052114
5
Concerning the aspect of an information signal arriving at the node from a second node
for retransmission to a sink connected to the node, the object is achieved by a node
having the features of claim 1; concerning the aspect of an information signal arriving
from a source connected to the node for retransmission to a second node, it is achieved
5 by a node having the features of claim 4. An input branching means which is arranged between the interfaces and the switching unit allows to supply information signals
arriving at the interfaces, in particular a working signal and a protection signal
associated to it, which necessarily arrive at different interfaces, to an optical receiver while avoiding the switching unit. Therefore, a failure of the switching unit can only
10 interrupt those information signals, which go through the node from one interface to another. Since, as indicated above, working and protection signals should not go through the same nodes, such a failure can never affect associated protection and working signals. Information signals which are to be dropped at the location of the node do not go through the switching unit and are therefore not affected by an eventual
15 failure thereof.
The same applies mutatis mutandis to supplying an information signal from a source into the network at a node. In order to supply working and protection signals of such a terminal, an output branching means is provided between each interface and die
20 switching unit and is adapted to supply an output channel to the interface either from the
switching unit or from the optical transmitter of a transponder. At the node where the
information signals are fed into the network, working and protection signals do not go through a same switching unit either.

WO 20*15/029905

PCT/F.P2004/052I14

In the simplest case, the branching means might be formed by a signal divider which transmits an information signal coming from a demultiplexer proportionally and simultaneously to an input of the switching unit and to a transponder, respectively, or
which superimposes output signals of the switching unit and of a transponder. In order
5 to avoid the power losses resulting therefrom, the branching means are preferably
formed as switches which, at a given instant, forward an information signal either only
to the switching unit or only to a transponder, or which receive an information signal either only from the switching unit or only from die signal converter unit
10 Transponders which have one output port of the demultiplexer or one input port of the multiplexer, respectively, assigned to them by which they are adapted to be connected
to the input or output branching means, respectively, should be provided in a number corresponding to mat of the input and output channels, respectively, in order to ensure
mat an information signal can be dropped or added at any arbitrary wavelength of the
15 multiplex.
Transponders which are adapted to supply an information signal with a selectable carrier wavelength to an output channel may be connected to a plurality of output channels by the output branching means.
20 In order to allow for bi-directional data traffic, each transponder preferably comprises a transmitter for an output channel and a receiver for an input channel. Transmitters and receivers should then be connected to the branching means of a same interface.

WO 2M05/U2W05 Pi T/EP2tM>4/»52114

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An additional advantage is achieved if the branching means not only supply incoming
information signals selectively to the branching unit or to one the transponders or
receive outgoing information signals selectively either from the switching unit or one of
die transponders, respectively, but are further capable of supplying information signals
5 from a transponder to the switching unit and vice versa. Thus, e.g., it becomes possible
first to extract an information signal, to regenerate it in the transponder and to supply it
again to the network from the same transponder, and, in case the transponders are
tunable, to change the carrier wavelength on which an information signal is transmitted.
10 Further features and embodiments of the invention become apparent from the subsequent description of embodiments, referring to the appended drawings.
Fig. 1, already discussed, shows a conventional node;
15 Fig. 2 shows a basic configuration of a node according to the invention;
Fig. 3 is a first simple embodiment of a branching means that may be used in the node; and
20 Figs. 4 and 5 show advanced embodiments of branching means.
The node of the invention shown in Fig. 2 as a block diagram is distinguished from the conventional one of Fig. 1 by the fact that each interface 1 of the node has a branching means 7 associated to it which is located at input and output channels 8,11 between the

WO 2WJ5/029905

PCT/EP20O4/05ZI14

8
concerned interface 1 and the input and output ports associated to it of switching unit 2, and which has a number of transponders 6 connected to it.
A first example of the branching means 7 is schematically represented in Fig. 3. N
5 information channels 8, each for one information signal, having carrier wavelengths 11,
..., IN go from an out-put port of demultiplexer 4 of interface 1 to switching unit 2. At
each of these input channels 8, a switch, e.g. a moveable mirror 9, is arranged, which, according to its position, either lets the information signal pass to switching unit 2 or deflects it towards receiver 10 of one of the transponders 6. A corresponding group of
10 mirrors 9 is arranged at output channels 11 for carrier wavelengths 11,..., IN which go
from output ports of the switching unit 2 to input ports of the multiplexer 5 of interface
1. In the represented configuration, the input channel 8 which guides the information
signal of carrier wavelength 11 is transmitted to a switching unit 2, while the
information signal of wavelength IN reaches one. of the transponders 6, where it is
15 converted into an electrical signal and is supplied to a terminal 12. The thus extracted information signal is the working signal of terminal 12. The terminal 12 is connected to
a further transponder, not shown, which is connected to a branching means 7, which is different from the one represented in Fig. 3 and which receives the protection signal by another interface 1.
20 The terminal 12 is further connected to a transmitter 13 of the transponder 6 in order to supply a working information signal to the network. The transmitter 13 operates at the
fixed wavelength IN. The optical signal from this transmitter 13 reaches a mirror 9,
which deflects it to an input port of the multiplexer 5 for the wavelength IN. The further

WO 2IH>5/»2W©5 PCT/EP2IMW/052J14
9
transponder, not shown, has a transmitter for transmitting the corresponding protection signal via the other interface. The terminal 12 can thus transmit a working information signal and a protection information signal without assistance from the switching unit 2.
5 In this embodiment, for each of the N possible carrier wavelengths, the transponders 6 must be connected to the branching means 7 in order to ensure that any information signal arriving at the branching means 7 can be extracted without regard of its carrier wavelength or that an information signal having the same carrier wavelength can be supplied in die opposite direction.
10 The embodiment of Fig. 4 only requires a smaller number of transponders 6. Each of these
transponders 6 has a transmitter 13 which is tnneable to a plurality of carrier
wavelengths li,.. IN, preferably to all wavelengths of the multiplex, and in each output
channel 11 mat corresponds to one of these carrier wavelengths, mere is a mirror 9 or a
15 switch having a similar functionality, which allows to supply an information signal
transmitted by transmitter 13 to one of these output channels 11. Inversely, in each input
channel 8 having a corresponding carrier wavelength, there is a mirror 9 for extracting
an information signal towards receiver 10 of this transponder 6. Since the receivers of
conventional transponders are usually sensitive to all wavelengths of the multiplex, such
20 a transponder may be connected to any pair of input and output channels 8,11,
according to need.
Fig. 5 is a further advanced embodiment of the branching means 7. This branching means comprises four groups of N by M mirrors, M being the number of transponders

WO 2IM>5/I>2WI>5

PCT/EP2004/052II4

10
6. A first group of mirrors 9a is for deflecting an incoming information signal from an input channel 8 to a transponder 6, like in Fig. 4; a second group 9b is for supplying an information signal from a transponder 6 to an output channel 11. A third group 9c is for deflecting an information signal from the output channel 11 to one of the transponders 6, and a fourth group 9d for supplying an information signal from a transponder 6 to an input channel 8.
The transponders 6 each have two switches 14,15 and an impulse shaping circuit 16. In a first position, the switches 14 connect the electrical signal ports of the receiver 10 and
10 the transmitter 13 of a transponder to ports for a terminal. In a second position they connect them to inputs and outputs of the impulse shaping circuit 16, so mat an extracted information signal received by receiver 10 is regenerated electrically in the impulse shaping circuit 16 and is men retransmitted as an optical signal by transmitter 13. Such a transponder 6 can be used for selectively extracting an attenuated information signal at an input channel 8, to re-amplify it and to supply it again to the same input channel 8 using one of mirrors 9d, in order then to switch it in the switching unit 2.
Further, it is possible to drop an information signal that arrives e.g. at an input channel 8 having carrier wavelength li, to convert it to another carrier wavelength ij using a transponder 6 and to supply it to the input channel 8 corresponding to this wavelength. This may be necessary if on the transmission line 3 by which the information signal is to be retransmitted from the concerned node, the carrier wavelength li is already occupied by--another signal.-As a new carrier wavelength Ij, preferably a carrier

■ WO 2M>5/«2!>W5 PCT/EP2MM/052I14
11
wavelength which is still available on the outgoing transmission line 3 is selected, provided that it is also available in the branching means 7. If this is not so, the information signal may be wavelength-converted twice, in both branching means 7 it passes on its way through the node.

04-07 -2005 . . EP04521I4
12 P63805.WOP/P S

CLAIMS
1. A node for an optical communication network having at least one switching unit (2), a plurality of optical interfaces (1) for connecting to a transmission line (3), which comprise a demultiplexer (4) for disassembling a multiplex signal arriving from a WDM transmission line into a plurality of input channels (8), each of which is supplied to an input port of the switching unit (2), and a multiplexer (5) for assembling a plurality of output channels (11), each originating from an output port of die switching unit (2), into an outgoing multiplex signal, and at least one receiver (10) for extracting an information signal from the communication network, characterized in that an input branching means (7) is located between each interface (1) and the switching unit (2) on the path of the input channels (8) and is adapted to supply an input channel (8) to the switching unit (2) as well as to the receiver (10).
2. The node of claim 1, characterized in that the input branching means (7) comprises, corresponding to each output port of the demultiplexer (4), a switch (9) for selectively connecting this output port to one of the input ports of the switching unit (2) or to the receiver (10).
3. The node of claim 2, characterized in that each receiver (10) has one output port of the demultiplexer (4) associated to it, to which it is connectable by die input branching means (7), and that the receivers (10) are provided in a number corresponding to the number of the input channels.

04-07-2005 EP0452
13 P63805. WOP/PS

4. A node for an optical communication network having at least one switching unit
(2), a plurality of optical interfaces (1) for connecting to a transmission line (3), which
comprise a demultiplexer (4) for disassembling a multiplex signal arriving from a WDM
transmission line into a plurality of input channels (8), each of which is supplied to an
input port of the switching unit (2), and a multiplexer (5) for assembling a plurality of
output channels (11), each originating from an output port of the switching unit (2), into
an outgoing multiplex signal, and at least one transmitter (13) for supplying an
information signal to the communication network, characterized in that an output
branching means (7) is located between each interface (1) and the switching unit (2) on
the path of the output channels (11) and is adapted to supply an output channel (11) to
the interface^) from the switching unit (2) as well as from the transmitter (13).
5. The node of claim 4, characterized in that the output branching means (7) comprises, corresponding to each input port of the multiplexer (5), a switch (9) for selectively connecting this input port to one of the output ports of the switching unit (2) or to the transmitter (13).
6. The node of claim 5, characterized in that the transmitters (13) are provided in a number corresponding to the number of the output channels (11), and that each transmitter (13) has one input port of the multiplexer (5) associated to it, to which it is connectable by the output branching means (7).

WO 2WfcV»29W5 PCTAEP2M04/052114
14
7. The node of claim 5, characterized in that the transmitter (13) is connectable to a plurality of output channels (11) and is adapted to supply an information signal having a selectable wavelength to an output channel (11).
'8. The node of claim 1,2 or 3 and claim 4,5,6 or 7, characterized by transponders
(6), each of which comprises one of the transmitters (13) and one of the receivers (10), wherein the transmitter (13) and the receiver (10) of a same transponder (6) is connected to the branching means (7) of a same interface (1).
9. The node of claim 8, characterized in that the input and output branching means
(7) are farmer adapted to supply to the switching unit (2) an input channel (8) from die
interface (1) as well as to supply it from one of the transponders.(6) and to supply an
output channel (11) from the switching rant (2) to an output channel (11) of die interface (1) and to one of die transponders (6
10. The node of one of die preceding claims, characterized in that each receiver (10) is an optical-electrical converter and each transmitter (13) is an electrical-optical converter.
11. The node of claim 10, characterized in mat at least one transponder (6) comprises z signal regenerator circuit (16).
12. A node for an optical communication network, substantially as herein
described and illustrated with reference to the accompanying drawings.
Dated, this 29* day of March , 2006.
(G. DEEPAK SRINIWAS)
OF K & S PARTNERS
AGENT FOR THE APPLICANT

V

15

Abstract
A node for an optical communication network comprises at least one switching unit (2), a plurality of optical interfaces (1) for connecting to a WDM transmission line (3), which comprise a demultiplexer (4) for disassembling a multiplex signal arriving from a WDM transmission line (3) into a plurality of input channels (8), each of which is supplied to an input port of the switching unit (2), and a multiplexer (5) for assembling a plurality of output channels (11), each originating from an out-put port of the switching unit (2), into an outgoing multiplex signal, and at least one transponder (6) for adding an information signal to and dropping it from the communication network, respectively. Input and output branching means (7) between each interface (1) and the switching unit (2) on the path of the input and output channels (8, 11), respectively, are adapted to supply an input channel (8) to the switching unit (2) or to the transponder (6), or to supply an output channel (11) from the interface to the switching unit (2) or the transponder (6).

Documents:

382-mumnp-2006-abstract(4-4-2006).pdf

382-MUMNP-2006-ABSTRACT(9-1-2009).pdf

382-mumnp-2006-abstract(granted)-(15-9-2009).pdf

382-mumnp-2006-abstract-1.jpg

382-mumnp-2006-abstract.pdf

382-MUMNP-2006-ASSIGNMENT(9-1-2009).pdf

382-MUMNP-2006-CANCELLED PAGES(9-1-2009).pdf

382-mumnp-2006-claims(4-4-2006).pdf

382-MUMNP-2006-CLAIMS(9-1-2009).pdf

382-mumnp-2006-claims(granted)-(15-9-2009).pdf

382-mumnp-2006-claims.pdf

382-mumnp-2006-correspondance-received.pdf

382-MUMNP-2006-CORRESPONDENCE(19-1-2009).pdf

382-MUMNP-2006-CORRESPONDENCE(9-1-2009).pdf

382-mumnp-2006-correspondence(ipo)-(16-9-2009).pdf

382-mumnp-2006-description (complete).pdf

382-mumnp-2006-description(complete)-(09-01-2009).pdf

382-mumnp-2006-description(complete)-(4-4-2006).pdf

382-mumnp-2006-description(granted)-(15-9-2009).pdf

382-mumnp-2006-drawing(4-4-2006).pdf

382-MUMNP-2006-DRAWING(9-1-2009).pdf

382-mumnp-2006-drawing(granted)-(15-9-2009).pdf

382-mumnp-2006-form 1(29-3-2006).pdf

382-MUMNP-2006-FORM 1(9-1-2009).pdf

382-mumnp-2006-form 13(19-1-2009).pdf

382-mumnp-2006-form 18(7-9-2006).pdf

382-mumnp-2006-form 2(9-1-2009).pdf

382-mumnp-2006-form 2(complete)-(4-4-2006).pdf

382-mumnp-2006-form 2(granted)-(15-9-2009).pdf

382-mumnp-2006-form 2(title page)-(4-4-2006).pdf

382-MUMNP-2006-FORM 2(TITLE PAGE)-(9-1-2009).pdf

382-mumnp-2006-form 2(title page)-(granted)-(15-9-2009).pdf

382-MUMNP-2006-FORM 26(19-1-2009).pdf

382-mumnp-2006-form 26(19-6-2009).pdf

382-MUMNP-2006-FORM 26(27-3-2007).pdf

382-MUMNP-2006-FORM 26(7-8-2006).pdf

382-MUMNP-2006-FORM 26(9-1-2009).pdf

382-mumnp-2006-form 3(16-1-2008).pdf

382-mumnp-2006-form 3(4-4-2006).pdf

382-MUMNP-2006-FORM 3(9-1-2009).pdf

382-mumnp-2006-form 5(4-4-2006).pdf

382-mumnp-2006-form-1.pdf

382-mumnp-2006-form-2.doc

382-mumnp-2006-form-2.pdf

382-mumnp-2006-form-3.pdf

382-mumnp-2006-form-5.pdf

382-MUMNP-2006-OTHER DOCUMENT(9-1-2009).pdf

382-MUMNP-2006-PETITION UNDER RULE 137(12-1-2009).pdf

382-mumnp-2006-specification(amended)-(9-1-2009).pdf

382-mumnp-2006-wo international publication report(4-4-2006).pdf

abstract1.jpg


Patent Number 236020
Indian Patent Application Number 382/MUMNP/2006
PG Journal Number 38/2009
Publication Date 18-Sep-2009
Grant Date 15-Sep-2009
Date of Filing 04-Apr-2006
Name of Patentee ERICSSON AB
Applicant Address Torshamnsgaten 23, Stockholn, Sweden
Inventors:
# Inventor's Name Inventor's Address
1 PILCHER, Olaf Hafnersweg 52, 71522 Backnang,
2 ELEBERS, Jorg-Peter Hufschmiedstr, 9 81249, Munchen, Germany
3 WELLBROCK, Glen 2750 Troy Road, Wylie, Texas, 75098,U.S.A.
PCT International Classification Number H04Q11/00
PCT International Application Number PCT/EP2004/052114
PCT International Filing date 2004-09-09
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 103 43 615.4 2003-09-20 Germany