Abstract: A packet-switched communications network (PSN) includes a multiplicity of nodes (Ni) adapted to switch streams of packets benefiting from circuit emulation services, known as CES packets. The network uses a particular method of resynchronizing the CES streams. According to that method, for a CES stream intended to take an associated path (CE) from an ingress node (N1) passing through a set of nodes including a subset of nodes adapted to resynchronize CES streams selectively, effective resynchronization of said stream by a node selected from said subset is conditioned by a value representative of the cumulative jitter suffered by said stream as far as that node.

Abstract: The present invention relates to an optical cross-connector (1000) of multi-granular architecture comprising a first switching stage (100) for switching composite digital optical signals, the switching stage comprising a first optical switching matrix (1 to 4), wavelength band demultiplexing and multiplexer means (10, 20; 10?, 20?), a second switching stage (200) for switching digital optical signals and comprising a second switching matrix (5), wavelength demultiplexing and multiplexer means (61 to 64; 61? to 64?), redirection outlet ports (11? to 42?) of the first matrix being coupled to direction inlet ports of the second matrix. The optical first matrix comprises a series of independent optical switching sub-matrices (1 to 4) disposed in parallel.

Abstract: A switch for an optical transmission network using wavelength division multiplexing has p1 input ports receiving p1 wavelengths and first switching means for switching the p1 wavelengths to p2 output ports, q1 input ports receiving q1 bands of wavelengths and second switching means for switching the q1 bands to q2 output ports, r1 input ports receiving r1 groups of bands and third switching means for switching the r1 groups of bonds to r2 output ports. The three switching means consist of a single switching matrix adapted to couple any of the p1+q1+r1 input ports to any of the p2+q2+r2 output ports. This single-matrix architecture can switch all the granularities at the same time, which facilitates reconfiguration as a function of evolution of the traffic to be switched.

Abstract: The present invention relates to a space cross-connect unit (Z) with N input ports (Ei) and P output ports (Si) more particularly suitable for packet-switched optical communications networks. The cross-connect unit comprises a broadcast stage comprising at most N signal dividers (Ai) each having an input and C outputs where C is an integer factor of P less than P, each input being connected to one of the N input ports (Ei) so that each of the N dividers (Ai) divides a signal received at one of the N input ports (Ei) into C signals at the C outputs, and a space switching stage comprising at most C space switching modules (Bi); each of the C modules (Bi) has N inputs and P/C outputs, the N inputs are connected to N outputs of the broadcast stage, each of the N outputs comes from a different divider (Ai), and each of the P/C outputs of the C modules (Bi) is connected to a respective one of said P output ports (Si).

Abstract: The switching system comprises input modules (IM1, IM2, IMi, IMn) each connected to a switching matrix (1) and to a corresponding controller (2). Each input module (IMi) organizes packets that it receives into digital data blocks with a fixed size, and makes transfers of these blocks by successive cycles to the matrix (1). Each of these blocks is organized into groups of digital data, these groups having corresponding modifiable sizes and being stored according to a predetermined order and associated with the corresponding output ports (OP1, OP2, OPj, OPn) in the system. Each of these groups is formed of packets to be sent to a single corresponding output port. Any block transfer to the matrix (1) is accompanied by transmission of information representative of the corresponding sizes of the groups of the transferred block to the said controller (2), and the groups of each transferred block are switched to their corresponding destination output ports as a function of this information representing the sizes.

Abstract: The present invention relates to the field of optical telecommunications networks, and more particularly to a method and to devices for backing up a ring optical telecommunications network. The method of the invention corresponds to a method of backing up a ring optical telecommunications network including a traffic concentrator (1) and a communications node (N3) interconnected by an optical fiber (2) (s1, s2) transported in the fiber and addressed to the node. The method of the invention comprises the following successive steps: while the network is being set up, a step of creating a virtual break (C) between the concentrator and the node; and when an at least partial real break in the fiber is detected that limits or interrupts the transmission of the signals to the node, a step of displacing the virtual break so that it coincides with the real break so as to re-establish the reception of the optical signals by the node.

Abstract: A device for processing optical signals comprises sources each delivering, substantially simultaneously, optical signals in accordance with a comb of at least two different wavelengths or a continuum of wavelengths. It further comprises multiplexers adapted to deliver to at least one primary port a multiplex of channels corresponding to chosen bandwidths produced from optical signals received at secondary ports each provided with selective spectral filters adapted to pass optical signals whose wavelengths belong to one of the bandwidths corresponding to one of the channels of the multiplex. It further comprises optical routers for routing the optical signals delivered by the sources to secondary ports of the first multiplexers as a function of instructions received.

Abstract: A method is disclosed of reconfiguring a ring optical network made using a single optical fiber (100). A traffic concentrator (120) and stations (140) are optically connected to the fiber. The concentrator sends a light signal to and receives a light signal from both ends of the fiber using two groups of wavelengths (110, 150) in order to be able to communicate with all the stations. When the network is established, a virtual break (170) is created between two stations. If a real break is detected in the optical fiber, then the virtual break is shifted until it coincides with the real break, thereby enabling traffic to be re-established between the concentrator and the stations. Each station is equipped with a three-state optical switch (400) for changing the direction of the light signals.

Abstract: The invention relates to a time division and wavelength division multiplex optical switching node for use in an optical communications network (2), which node combines a set of time division multiplex packets (8-1, 8-2, . . . , 8-i) into a wavelength division multiplex packet (18) to form a composite wavelength division multiplex packet, in particular by conferring on each time division multiplex packet (8-1, 8-2, . . . , 8-I) a respective appropriate multiplexing wavelength (&lgr;1, &lgr;2, . . . , &lgr;i), for example a wavelength specific to each time division multiplex packet. The invention has applications in high bit rate optical networks in particular, in which it offers versatility and transparent use of the different multiplexing modes.

Abstract: To optimize the resources of an optical transmission network using wavelength division multiplexing, assigning carrier frequencies to signals to be transmitted consists in associating N sets of optical frequencies of the comb with N respective ranges of consecutive error rate values, each of the sets comprising frequencies generating a mean error rate in the associated range, defining a measured signal transmission constraint level that is a function of the transmission constraint parameter(s) and may take N distinct values referred to as constraint values, associating the N constraint values in increasing order respectively with the N sets of frequencies in decreasing order of the error rate values of the associated N ranges, assigning any signal to be transmitted a constraint value obtained by applying the measurement, and assigning the signal to be transmitted a carrier frequency belonging to one of the sets of frequencies that is associated with a constraint value at least equal to the constraint value as

Abstract: An optical demultiplexing system demultiplexes a multiplex which has at least three levels of granularity and includes m interleaved bands of wavelengths each of which includes p wavelengths. The system includes a 1-to-m deinterleaving demultiplexer for demultiplexing the multiplex into m bands of wavelengths and a 1-to-p deinterleaving demultiplexer for demultiplexing each of the m bands into p wavelengths. The numbers m and p are mutually prime.

Abstract: A method of measuring the error rate of an optical transmission system transmitting a signal by detecting the signal, and asynchronously sampling the signal at a frequency independent of the bit rate of the signal to obtain K samples of the signal at respective times t1 to tK, where K is an integer greater than or equal to 2. The eye diagram of the signal, the error rate of the signal and the bit time of the signal are then computed.

Abstract: The present invention relates to an optical cross-connect unit of multigranular architecture (1000) including a first stage (100) for switching wavelength bands and including an optical switching matrix for switching wavelength bands, demultiplexing and multiplexer means (10 to 20′)for demultiplexing and multiplexing wavelength bands, a second stage (200) for switching wavelengths and including a switching matrix for switching wavelengths, and demultiplexing and multiplexer means (30 to 60′) for demultiplexing and multiplexing wavelengths. The first matrix of the invention includes a series of first optical switching submatrices (1, 2) disposed in parallel and the second matrix of the invention includes a series of second switching submatrices (3, 4) disposed in parallel.

Abstract: The present invention relates to a method of monitoring the transmission of optical signals including a step of inserting a monitoring signal (S) more particularly suited to monitoring the quality of service. During the transmission of optical signals each carried by a predefined wavelength defining a transmission channel (Ci), said signals are grouped onto the same fiber in a band (B) of channels. The method then includes a step of simultaneously modulating said signals grouped in the band of channels using the monitoring signal to be transmitted, so that each of the signals constitutes a carrier of the monitoring signal.

Abstract: This optical telecommunications network (1000), of metropolitan area type, comprises a ring type core (10), and secondary rings (41, 42; 43, 44). In each sending access node (11), means (111) for sending information-carrying optical signals use a wavelength belonging to a group of wavelengths dedicated to the secondary ring (41, 42) to which this sending access node (11) is connected. In each destination access node (21), receiving means (212) are capable of receiving all the wavelengths used by sending nodes (11) of the network. Insertion means (1, 2) comprise all-optical means (100, 101, 10; 201, 20) for inserting, into the core fibre (10), optical signals sent by a sending access node connected to these insertion means. Extraction means (31, 32) comprise optical couplers for taking from the core fibre (10) a so-called representative signal formed of a fraction of the power of each information-carrying signal, these couplers being respectively coupled to said receiving means of the destination nodes.

Abstract: The present invention relates to a method of measuring the error rate of an optical transmission system transmitting a signal, said method comprising the following operations:

Abstract: A reconfigurable directional optical system comprises N ports that can be configured individually as inputs or outputs. A system of this kind comprises at least one optical device having unidirectional inputs and outputs the total number of which is equal to or less than N, and an N×N optical switch such that each of the ports can be coupled interchangeably either to one of the inputs or to one of the outputs of the optical device.

Abstract: A method is disclosed of reconfiguring a ring optical network made using a single optical fiber (100). A traffic concentrator (120) and stations (140) are optically connected to the fiber. The concentrator sends a light signal to and receives a light signal from both ends of the fiber using two groups of wavelengths (110, 150) in order to be able to communicate with all the stations. When the network is established, a virtual break (170) is created between two stations. If a real break is detected in the optical fiber, then the virtual break is shifted until it coincides with the real break, thereby enabling traffic to be re-established between the concentrator and the stations. Each station is equipped with a three-state optical switch (400) for changing the direction of the light signals.

Abstract: A device for erasing overhead modulation of an optical signal, wherein said optical signal is injected into an optical device able to modulate the optical signal (for example a semi-conductor optical amplifier driver by a bias control) and for which one an automatic gain control does not need to detect the residual overhead modulation, is characterised in that said bias control means applies to said amplifier a compensation voltage presenting a modulation out of phase with respect to said overhead modulation, and in that modulation index of said compensation voltage is (substantially) proportional to the modulation index of said optical signal.

Abstract: The invention relates to an optical demultiplexing system for separating frequency bands of a frequency-division multiplex, said system comprising a 1 to n first cyclic demultiplexer for demultiplexing said multiplex into n interleaved frequency combs each comprising m channels and a second cyclic demultiplexer for separating the channels of said n interleaved combs to obtain m consecutive bands comprising n consecutive frequencies, characterized in that said second multiplexer is an m to m cyclic demultiplexer having n input ports connected to respective output ports of said 1 to n first cyclic demultiplexer and in that the numbers n and m are mutually prime numbers.