FR2552962A1 - Device for reducing the energy consumption of circuits for transmitting towards subscribers, with bidirectional wavelength multiplex - Google Patents

Abstract

Device for reducing the consumption of transmission circuits in integrated services urban networks with fibre optic transmission paths. The components of the transmission circuits are in a standby condition, in which only those components required for switching into the normal service condition can operate. This switching is performed by a logic signal "into", which connects a parallel-series converter 2 to the service voltages. The data stream D is accompanied by a bit frequency BT which switches in the electro-optic converter 3 on transmission, and then the series-parallel converter 5 on reception. The circuit is thus established. The suppression of the logic signal "into" in the S/C circuit 6 returns the transmission circuit to the standby condition after performing the service.

Description

 The present invention relates to a device for reducing the energy consumption of transmission circuits towards the subscriber with a bidirectional wavelength division multiplex, in which each transmission circuit operating at an optical wavelength is formed by coupling. in series of a parallel series converter, an electro-optical converter, an optical transmission channel common to all wavelengths (optical fiber), an optoelectric converter and a serial-parallel converter.

In integrated service urban networks with fiber optic transmission channels, i.e. urban networks in which several types of services (such as telephony, fax, telex, television) are provided by light transmission on one channel in optical fiber, provision should be made for the future adoption of the wavelength-multiplex transmission method, for the following reasons a) Extension of the capacity of the channels terminating at the subscriber
without increasing the bit rate on the channel considered, which
is operated at a predetermined wavelength; b) abolition of earthworks for the burial of
cables in case of capacity expansion; c) possibility of having more than 20 channels if necessary
broadband for transmission between the exchange and the subscriber;
and d) application of the same technology for transmitting terminals
and reception, independently of the optical equipment.

 The consumption of all the components of a transmission circuit to the subscriber in one direction and comprising only one electro-optical converter (laser transmitter for example) is currently around 12 W. The application of the wavelength multiplexing process, that is to say the provision of channels operating at different wavelengths, thus leads to significant consumption, both at transmission and at reception and independently whether the circuit transmits information or not.

 L1iw: ention aims to reduce the significant consumption = z.ation.

 According to an essential characteristic of the invention, the circuit is coma..uted from the standby state to the service state, after the application of a logic signal "at" to a device for connecting the parallel converter - series at all operating voltages, by the resulting transmission of a bit frequency BC to the electro-optical converter and to the serial-parallel converter, which are equipped with devices for detecting the frequency and triggering an operation of switching, as well as by detecting an optical level at the input of the optoelectric converter; and the circuit automatically returns to the waiting state after the suppression of the signal "by" following the execution of the transmission service 1.

 The waiting concept is the essential element of the solution according to the invention. It designates the fact that only the part of the equipment of a circuit which is absolutely essential is kept fully available to allow, if necessary, the complete restoration of total operation on the circuit in question.

The consumption of the aforementioned essential equipment is much lower than that required for full operation.

The concept according to the invention makes it possible to achieve savings corresponding to a reduction factor of between 17 and 20. The switching from standby to total availability must be carried out using signals also transmitted on the circuit in normal service. The notable length of the subscriber lines also prohibits, for economic reasons, the laying of particular signal or remote control lines with the optical cable. The invention has the following advantages.

1. The waiting concept reduces energy consumption by a ratio of 17 to 20.

2. No additional signaling line is necessary.

3. Switching from one operating state to another is possible
for both dispatch and service
conversational defects.

 Other characteristics and advantages of the invention will be better understood using the detailed description below of an exemplary embodiment and the appended drawings in which FIG. 1 represents the main components for transmission in one direction; FIG. 2 represents the optical transmission circuit for conversational applications; and FIG. 3 represents the establishment-release circuit (EiAj circuit.

Figure 1 shows that at the input of transmitter 3 at a length
the data arriving in parallel form are first serialized in a parallel-series converter 2, then brought to a bit rate of 140 'fbit / s for example.

 This assumes that data present in analog form is first digitized and, where appropriate, combined with other digital data, by a multiplexer not shown, in a sequence of messages in parallel. The parallel data are accompanied by clock frequencies, which produce their loading in the parallel serial vert conconisstrtr 2. The clock frequencies are also used for the delivery of data stored at the output of the parallel converter series 2. This allows the loading serial data in the electro-optical converter 3. The serial data flow D is then accompanied by a bit frequency BT having a fixed phase shift, the two being applied to the electro-optical converter (laser transmitter).

 The bit frequency BT is necessary on the electrooptical converits 3 to be able to carry out the known interference on the transmission circuit, in order to facilitate recovery of the clock frequency from the reception side.

The laser transmitter 3 converts the electrical signals into optical signals with a wavelength Wi. At the end of the optical transmission path 3a, these signals are detected (identified) by an opto-electric converter 4. They are thus converted into electrical signals in the form of a serial data stream
D accompanied by a LV bit frequency with a fixed phase shift.

The bit frequency BT is delivered in a known manner by a phase regulation loop (plus), the frequency of which is synchronized by the edges of the scrambled data received.

 Lines D and BT are connected to a serial converter 5, which delivers data in parallel and thus allows subsequent processing of data at lower frequencies, using technology with lower consumption.

 If the circuit is in the standby state, it must be possible to switch it to the full service state (circuit switching).

 To do this, the parallel-series converter 2 is first supplied by all the operating voltages. The connection of the service voltages takes place in a separate circuit, which the application of a logic signal 'ff to the input e / has operated.

After its connection, the parallel-series converter 2 delivers the bit LV frequency to the electro-optical converter 3. The detection of the bit BT frequency in a part of the electro-optical converter circuit constitutes for the latter the criterion for passing the state of 'waiting in the state of service. The optical level delivered by the converter 3 and then received by the opto-electric converter 4 on the reception side is converted opto-electrically, amplified, then applied to a detector. The detector output signal also leads in the receiver to the transition from the standby state to the operating state by connection of the supply voltages using a part of the circuit controlled by the detector. When the operating state is established, the opto-electric converter 4 delivers a bit frequency BT in addition to a serial data flow D. This bit frequency is obtained from the phase regulation loop PLL of the opto converter electrical 4, which is synchronized by the flanks of the data of the flow D. Before the transmission to the serial-parallel converter 5, the interference of the data flow D is eliminated in the optoelectric converter 4.

 The output of the bit frequency BT on the optoelectric converter 4 is identified by a detector of the serial converter 5 and switches the latter from the waiting state to the operating state by connecting the supply voltages, the same way that for the converter 4.

 In the standby state, only the devices for stabilizing the electro-optical converter 3 (the cooling devices for example) and the detectors identifying the optical level on the opto-electric converter 4 and the bit frequencies in operation are in operation. the electro-optical converter 3 and the series-parallel converter 5. The energy required is equal to approximately the 20th of that consumed by the circuit in service.

 This sequence of operations of connection by the active components of the optical transmission circuit operating at wavelength X. establishes and maintains the service state as long as the establishment criteria are present. The removal of the logic signal "at" at the I / O input necessary for the connection of the parallel-series converter 2 produces the transition from the operating state to the waiting state, in the reverse order of the operations described above. , that is to say that the transition from the service state to the standby state and vice versa is possible at any time by detection of the service signals of the optical transmission circuit.

The circuit can thus be kept in service as long as it takes to provide services; the state of service can then be abandoned without harmful consequences for the subscriber.

 In general, the subscriber does not only receive dispatch services, but also wishes to establish conversational services; the establishment in one direction must therefore be accompanied by the establishment of the corresponding return direction. To do this, it is necessary to derive on the receiver of wavelength X. a signal having the same action as the application of the logic signal "en" to a circuit operating at wavelength X. and used for transmission back.

 FIG. 2 shows that an additional circuit is used to do this in the serial-parallel converter 5 for the detection of the synchronization block of the received time frame.

When this synchronization block is present, a logic signal "Sync" is delivered and is used to establish the return transmission.

 The return transmission circuit consists of components 2 'to 6', which are comparable to components 2 to '6. It should however be noted that the synchronous signal "Sync" must not have the same action as the signal d 'establishment' in ', failing which a loop forms on the two circuits, which leads to continuous service and would prohibit a release of the circuits.

This is why the identical E / A circuits 6 and 6 'are used to combine the two signals "Sync" and "en". They prohibit the aforementioned formation of a loop.

 Figure 3 shows the E / A circuit 6 (or 6 '). it ensures the decoupling of the logic signal "en" and the logic signal "Sync", which act on the e / a input of the parallel-series converter 2 or 2 'according to the combination described below. The decoupling of the aforementioned two logic signals "en" and "Sync" is obtained by converting the transition from static logic signals to pulses by the pulse shapers 7 to 10. The pulses delivered by the shapers 7 or 8 during the application of the "Sync" or en "signals are transmitted by the NAND operator 13 to the reset input 1 of the R / s flip-flop constituted by two other NAND operators 11 and 12. the signal output of the R / S flip-flop is transmitted by an inverter 15 to the e / a input of the parallel-series converter 2 or 2 '. The pulses delivered by the conformers 9 or 10 when the "Sync" signals are deleted or "en" reset the flip-flop R / s il et 12.The E / A circuit has the following advantage: each of the aforementioned signals is active on a transition, that is to say that each signal can establish or release the circuit regardless of the state of the other signal, the above formation of a loop is therefore no longer possible.

The return transmission circuit operating at wavelength X. is made up of components comparable to those of the
J go circuit (at wavelength Ai) so that the introduction of a standby state possibility saves on the return circuit the same amount of energy as on the go circuit
As a service to the subscriber is possible both in a directional sense and in conversational mode at wavelength X., the I / O circuit 6 must in this case include an OR output, so that other signals of The establishment of other services (television for example) can also establish the circuit at this wavelength.

 Of course, various modifications can be made by those skilled in the art to the principle and to the devices which have just been described only by way of nonlimiting examples, without departing from the scope of the invention.

Claims (5)

Claims 1. Device for reducing the energy consumption of transmission circuits towards the subscriber with bidirectional multiplex in wavelength, in which each transmission circuit operating at an optical wavelength is constituted by the coupling in series d '' a parallel-serial converter, an electro-optical converter, an optical transmission channel common to all wavelengths (optical fiber), an optoelectronic converter and a serial-parallel converter, said device being characterized in that the circuit is switched from the standby state to the operating state, after the application of a logic signal "at" to a device for connecting the parallel-series converter 2 to all the operating voltages, by the resulting transmission of a bit frequency BT to the electro-optical converter 3 and to the serial serial converter 5, which are equipped with devices for the detection of the bit frequency and the initiation of a switching, as well as by detecting an optical level at the input of the opto-electric converter 4; and the circuit automatically returns to the waiting state after the elimination of the logic signal i'en "following the execution of the transmission service. 2. Device according to claim 1, characterized in that a) the devices for stabilizing the electro-optical converter  3 (example: Peltier element cooling device), b) the optical level detector in the opto converter  electric 4, and c) the detectors identifying the bit LV frequencies in the con  electro-optical vertiser 3 and the serial-parallel converter  5 are connected in the waiting state. 3. Device according to claims 1 and 2, characterized in that for the transmission of conversational services, the synchronous signal "Sync" of the time multiplex frame is used on the serial-parallel converter 5 for establishing the corresponding return direction, said signal being delivered by an additional circuit in the series-parallel converter 5. 4. Device according to claims 1 to 3, characterized in that a combination of the logic signal "at" and the synchronous signal "Sync" is provided in an I / O circuit 6 for the automatic establishment of the corresponding return direction. 5. Device according to claim 4, characterized in that the E / A circuit 6 converts the transition from static signals "into" and "Sync" into pulses to avoid signal loops.