CA2049780A1 - Passive optical telecommunication system - Google Patents
Passive optical telecommunication systemInfo
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- CA2049780A1 CA2049780A1 CA002049780A CA2049780A CA2049780A1 CA 2049780 A1 CA2049780 A1 CA 2049780A1 CA 002049780 A CA002049780 A CA 002049780A CA 2049780 A CA2049780 A CA 2049780A CA 2049780 A1 CA2049780 A1 CA 2049780A1
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- telecommunication
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- electro
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- 230000002457 bidirectional effect Effects 0.000 claims abstract description 16
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- 238000005516 engineering process Methods 0.000 description 1
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- RGNPBRKPHBKNKX-UHFFFAOYSA-N hexaflumuron Chemical compound C1=C(Cl)C(OC(F)(F)C(F)F)=C(Cl)C=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F RGNPBRKPHBKNKX-UHFFFAOYSA-N 0.000 description 1
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Abstract
ABSTRACT OF THE DISCLOSURE
A passive optical telecommunication system comprises a passive light waveguide bus network with optical branchers extending between a central telecommunication equipment and a plurality of decentralized telecommunication equipment. An electro-optical transmission element, an opto-electrical receiving element and a filter for bidirectional wave-division multiplexing are respectively structurally combined to form an electro-optical/opto-electrical transmitting/receiving module only in the decentralized telecommunication equipment and the electro-optical transducer, opto-electrical transducer and a filter for bidirectional wave-division multiplexing are respectively structurally separate, discrete components only in the centralized telecommunication equipment.
A passive optical telecommunication system comprises a passive light waveguide bus network with optical branchers extending between a central telecommunication equipment and a plurality of decentralized telecommunication equipment. An electro-optical transmission element, an opto-electrical receiving element and a filter for bidirectional wave-division multiplexing are respectively structurally combined to form an electro-optical/opto-electrical transmitting/receiving module only in the decentralized telecommunication equipment and the electro-optical transducer, opto-electrical transducer and a filter for bidirectional wave-division multiplexing are respectively structurally separate, discrete components only in the centralized telecommunication equipment.
Description
BACKGRQUND OF THE INVENTlOi~
Field of the Invention:
The present invention relates to a passive optical telecommunication system having passive light waveguide bus networks with optical branchers extending between a central telecommunication equipment and a plurality of decentralized telecommunication equipment. More specifically, the invention relates to such a system in which an electro-optical transmission element and an opto-electrical receiving element are employed, the receiving element connected to a filter for bidirectional wave-division multiplexing, these elements being structurally combined to form an electro-optical/opto-electrical transmitting/receiving module only in the decentralized telecommunication equipment and the electro-optical transducer, the opto-electrical transducer and a filter for bidirectional wave division multiplexing are respectively structurally separate, discrete components only in the centralized telecommunication equipment.
Description of the Prior Art Recent developments in telecommunication technology have lead to passive optical telecommunication systems in ~he level of the subscriber lines wherein a plurality of decentralized equipment (subscriber locations or what are referred to as remote units that respectively combine a plurality of subscriber locations) are each respectively connected via a separate light waveguide central office line to an optical brancher that is connected via a light waveguide bus, either directly or via at least one further optical brancher, to a common light waveguide terminal of a central equipment which, in particular, is established a switching center. in this connection, one is referred to the European Patent Application 0 171 080, ISSLS '88, Conf. Paper 2~s~0 9.4.1...5, and the BR Telecom Technol. J., Vol. 7, 1989, Vol No. 2, pp. 1~0-113 In such a telecommunication system, the signal transmission from the central equipment (switching center) to the decentralized equipment can be preferably undertaken in a burst stream (particularly an asynchronous transfer mode (ATM) cell stream) fromwhich each decentralized equipment takes only the bursts (ATM cells) intended therefor; the signal transmission from the decentralized equipment to the central equipment (switching center) can be undertaken in accordance with a TDMA method in which a decentralized equiprnent transmits each burst (ATM cell) synchroni~ed with the assistance of a delay device that is set in an apparatus-associated manner by the switching center, so that it does not intersect on the common light waveguide terminal of the central equipment (switching center) with burst of other decentralized equipment (see European patent application 0 171 080, European Patent ~pplication 0 318 331, European patent application 0 337 619 and the German patent 4 014 396).
The introduction of new telecommunication systems having light waveguide central office lines is quite generally dependent on the type and scope of the telecommunications infrastructures already existing, together with the telecommunication services offered therein, and, on the demand for new broadband communication services. The potentially-greatest connection volume is thereby envisioned in the area of private households. This potential for connections, however, will only crystallize to an effective demand for connections given correspondingly-low costs of a broadband subscriber line.
In this context, it is known ffor example from Telcom Report, Vol. 11, 1988, pp. 1-5, FIG. 6) for the subscriber lines of a light waveguide telecommunication system to structurally combine the electro-optical transducer, for example a laser diode, rsspectively required for ths transmission of an optical signal with the opto-electrical transducer, for example a PIN diode, required for the reception of an optical 2~14~3~7 signal and a filter for bidirectional WDM operation to form an integrated electrical-optical/opto-electrical transmitting/receiving module for bidirectional transmission.
Such a utili~ation of a uniform module type having optimum cost-benefit components in all telecommunications of the subscriber line level of a light waveguide telecommunication system leads, on the one hand, to a corresponding cost reduction, but, on the other hand, runs contrary to the further requirement existing in this context of being able to connect an optimum plurality of decentralized telecommunication locations in the subscriber line level to a central telecummunication location. This latter situation, in particular, assumes that the system can bridge optimally-great attenuations, this fundamentally requiring the utilization of higher-quality, but more cost-intensive modules, as well as, for example, higher-power laser diodes as the electro-optical transmlssion elements and avalanche photodiodes as opto-electrical receiving elements, as intrinsically known (for example, from Telcom Report, Vol. 10, 1987, Special "Multiplex-und Leitungseinrichtungen", pp. 146-150 and 150-159).
SUMMARY OF THE INVENTION
~ he object of the present invention is to overcome the aforementioned contradictory demands in passive optical telecommunication systems.
The present invention is directed to a passive optical telecommunication system having a central telecommunication equipment and a plurality of decentralized telecommunication equipment, each of which is respectivaly connected via i~s own light waveguide central office line to an optical brancher that is connected via a light waveguide bus, either directly or at least by way of one further optical brancher, to a common light waveguide terminal of the central telecommunication equipment, whereby each of the telecommunication equipment is equipped with an electro-optical 2~ 7 transmitting element and with an opto-electrical receiving element, as well as with a filter for wavelength-division multiplex ~WDM) operation (bidirectional WDM) This telecommunication system is, according to the present invention, particularly characterized in that the electro-optical transmitting element, the opto-electrical receiving element and the filter are structurally combined into an electro-optical/opto-eiectrical transmitting/receiving module for bidirectional transmission only in the decentralized telecommunication equipment and the electro-optical transducer, the opto-electrical transducer, the opto-electrical transducer and the filter form structurally discrete components only in the central telecommunication equipment.
While retaining a high number of units (or even increasing the number of units) of a cost-effective, uniform transmitting/receiving module for the plurality of decentralized telecommunication equipment, the present invention yields the advantage of being able to utilize a high-power electro-optical transmitter, such as a laser diode having a more complex control, as well as a more sensitive electro-optical receiver, such as an avalanche photodiode in the centralized telecommunication location, and, therefore, with a correspondingly^lower number of units, and of thereof being able to increase what is referred to as the power budget in the telecommunication system, i.e. the bridgeable attenuation, by approximately 5---10 dB .
This allows the path length to be lengthened or, respectively, allows an increase in the branching factor by a factor of, for example, 2--~4, and, as seen from the point of view of the optical power, allows a doubling through quadrupling of the number of decentralized telecommunication locations that can be connected to one and the same centralized telecommunication location.
For bidirectional optical message transmission via a light waveguide between a central transmission and/or receiving station and at least one decentrali~ed transmission and/or receiving station (subscriber station), it should be noted that it is 9~7~3U
known (from the German application 3 506 715) to proceed in such a fashion that:
messages are transmitted with different bandwidths in opposite directions;
a light a first wavelength belonging to the greater bandwidth has a significantly lower optical spectral width than a light of a second - wavelength belonging to the lower bandwidth;
at least the wavelength of the second light lies in the region of the minimum of the overall dispersion of the light waveguide;
the optical spectrum of the second light radiation is shaped by an optical filter such that the first light radiated can likewise be transmitted in the region of the minimum of the overall dispersion of the light waveguide;
and a light-emitting diode generates the second light radiation and a semiconductor laser or a super-emitting diode generates the first light radiation.
Light-emitting diodes are thereby referred to as cost-effective electro-optical transmitters that can be employed in the subscriber locations. However, greater relevancy than this with the present invention is not establishsd.
It should also be noted that a bidirectional light waveguide telecommunication system for wavelength-division multiplex operation (WDM operation3 between a centralized telecommunication location and a plurality of decentralized telecommunication locations having a passive light waveguide bus network extending therebetween has already been constructed in such a manner that an electro-optical transmitting element and an opto-electrical receiving element that are designed for wavelength-division multiplex operation are only provid0d in the centralized telecommunication location, whereas a combined opto-electrical receiving/electro-optical transmitting module that is respectively free of wavelength filters, works in a time separation transmission mode and is designed ~or a transmitting light having a wavelength for whose reception the central telecommunication location is designed is provided in the decentralized telecommunication locations, whereby the combined opto-electrical receiving/electro-optical transmitting module can be formed with a laser diode used in alternation as a receiving diode or can be formed with a laser module whose monitor photodiode is utilized in al~ernation as a receiving diode (see European application 0 419 710); here, also, there is no greater relevancy than this wi~h respect to the present invention.
Further characteristics of the present invention rnay be seen from the following, more detailed explanation of an exemplary embodirnent of the invention with reference to the drawing.
BRIEF DESCRIPTION OF THE DRAWING
Other objects, features and advantages of the invention, its organization, construction and operation will be best understood ~rom the ~ollowing detailed description, taken in conjunction with the accompanying drawing, on which there is a single figure schematically illustrating a bidirectional light waveguide telecommunication system having a passive light waveguide bus network.
The bidirectional light waveguide telecommunication system shown on the clrawing is only illustrated with a scope necessary for an understanding of the invention.
DESCRIPTION OF THE PKEFERRED EMBODIMENTS
As illustrated on the drawing, a bidirectional light waveguide telecommunication system comprises a passive (preferably monomode) light waveguide bus network BPON extending between a centralized telecomrnunication location, represented by a switching center VSt, and a plurality of decentralized telecommunication equipment, represented by a plurality of remote units DU2 and DU3. In this light waveguide telecommunication system, the remote units DU are connected via a single fiber light waveguide bus OB to a common light waveguide multiplex terminal of the switching center VSt. It is here assumed ~hat the equipment-associated light waveguide central office lines OAL1,...,0ALn are connected with the appertaining light waveguide bus OB via passive, i.e. non-wavelength selective, optical branchers V1,..., Vn that, for example, are accommodated in cable branching housings and being connected thereto, in particular, either directly or via additional such branchers. For example, tandem mixers or optical directional couplers ~an be employed as optical branchers. It is also possible to provide a shared optical brancher for a plurality of equipment-associated light waveguide central office lines, as intrinsically known in the art (for example, from the European application 0 171 080 and as such, therefore, need not be set forth in greater detail herein.
A wavelength-division multiplex operation (bidirectional wavelength-division multiplexing) is provided for separating the directions in the telecommunication system outlined on the drawing in that light of a first wavelength A1 Iying, for example, 7~3 in the 1300 nm band is employed for signal transmission in the downstream direction from the centralized telecommunication location VSt to the decentralized telecommunication locations...., DU2, ~U3,...and light having a somewhat longer, second wavelength ~2 Iying, for example, in the 1500 nrn band is employed for the signal transmission in tne upstream direction from the decentralized telecommunication locations..., DU2, DU3,...to the centralized telecommunication location VSt. To this end, appropriate electro-optical transmission elements, opto-electrical receiving elements and filters for wavelength-division multiplex operation are provided in ~he switching center VSt that forms the centralized telecommunication location and in the remote units...., DU2, DU3,...that form the decentralized communication locations. As indicated on the drawing, the electro-optical transmitting element SD, the optical-electrical receiving element ED and the filter F for the wavelength-division multiplex operation (bidirectional WDM operation) are structurally combined to form an electro-optical/optical-electrical transmitting/receiving module o l e and a wavelength-selective, optical filter W form structurally discrete, separate components only in the centralized telecommunication equipment VSt. A well-known optical filter, for example as known from U.S. 4,790,616, fully incorporated herein by this reference, may be provided as the optical filter component W and with an interference beam splitter and can, therefore, be provided as the filter, a known laser module, for example as known from the Telcom ~eport Vol. 10, 1987, Special "Multiplex-und Leitungseinrichtungen", pp.
146-150, FIG. 4, can be provided as an electro-optical transducer elo and a component having an avalanche photodiode that is likewise commercially can be provided as an opto-electrical transducer o l e.
As indicated on the drawing, the signal transmission in the outlined telecommunication system from the switching center VSt downstream to the decentralized equipment..., DU2, DU3,...on the wavelength ~1 can then be undertaken in a burst stream Zdo~ for example an A~M cell stream. Such ATM cells (respectively 7~3 covering 53 bit octets) are each respectively composed of a control information field (header, 5 octets) and of a useful information field (covering 48 octets). What is referred to as the virtual path identifier (covering 16 bits) is part of the header and what is referred to as the access control field is another part of the header.
When no useful information is to be transmitted, synchronization cells having a prescribed bit pattern for synchronization ~f the decentralized equipment on the basis of the respective cell start can be mixed into the ATM cell stream Zdow~ (what is referred to as pure ATM; however, it is possible that the ATM cell stream is, in turn, embedded in a ffor example, SONET) time-frame structure having synchronization signals (overhead) appearing at specific, fixed inteNals (what is referred to as frame-structured ATM~.
Each decentralized equipment DU takes only the bursts intended therefore from the burst stream (ATM cell strearn) Zdowr~ i.e. those ATM cells in the example that are addressed in their header, preferably in the virtual path identifier thereof, with an identifier assigned to the particular decentralized equipment DU. The subdivision into header and useful information fields is shown on the drawing for four ATM cells of an ATM cell stream Zdowr~ whereby the identifiers (3, 3, 2, n) recited in the headers of these four ATM cells indicate that the first two cells, carrying useful information A and D, are intended for the decentralized equipment DU3, that the third cell, carrying a useful information C, is intended for the decentralized equipment DU2, and that the fourth cell, carrying a useful information D, is intended for decentralized equipment that can be reached via the light waveguide subscriber iine C)ALn, but which is not shown on the drawing.
In the opposite transmission direction, the signal transmission from the decentralized equipment (remote units) DU upstream to the switching center VSt on 978~
the wavelength ~2 can be undertaken in accordance with a TDMA method with bursts(potentially, ATM cells) Zup in accordance wherewith a decentralized equipment DU
transmits each burst synchronized with the assistance of a delay device ~hat is set in association with that remote equipment by the switching center VSt, so that each burst in the upstream direction is transmitted in a time slot reserved for the appertaining decentralized equipment D~J and a burst does not intersect on the shared light waveguide terminal of the centralized equipment VSt with bursts of other decentralized equipment DU. Such a synchronization of the centralized equipment DU is already known in the art and is disclosed, for example, in the European patent application 0171-080, the European patent application 0 318 331, the European patent application 0 337 619 and the German application P 4 014 396, and therefore does not have to be discussed in further detail herein.
Although I have described my invention by reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. I therefore intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of my contribution to the art.
Field of the Invention:
The present invention relates to a passive optical telecommunication system having passive light waveguide bus networks with optical branchers extending between a central telecommunication equipment and a plurality of decentralized telecommunication equipment. More specifically, the invention relates to such a system in which an electro-optical transmission element and an opto-electrical receiving element are employed, the receiving element connected to a filter for bidirectional wave-division multiplexing, these elements being structurally combined to form an electro-optical/opto-electrical transmitting/receiving module only in the decentralized telecommunication equipment and the electro-optical transducer, the opto-electrical transducer and a filter for bidirectional wave division multiplexing are respectively structurally separate, discrete components only in the centralized telecommunication equipment.
Description of the Prior Art Recent developments in telecommunication technology have lead to passive optical telecommunication systems in ~he level of the subscriber lines wherein a plurality of decentralized equipment (subscriber locations or what are referred to as remote units that respectively combine a plurality of subscriber locations) are each respectively connected via a separate light waveguide central office line to an optical brancher that is connected via a light waveguide bus, either directly or via at least one further optical brancher, to a common light waveguide terminal of a central equipment which, in particular, is established a switching center. in this connection, one is referred to the European Patent Application 0 171 080, ISSLS '88, Conf. Paper 2~s~0 9.4.1...5, and the BR Telecom Technol. J., Vol. 7, 1989, Vol No. 2, pp. 1~0-113 In such a telecommunication system, the signal transmission from the central equipment (switching center) to the decentralized equipment can be preferably undertaken in a burst stream (particularly an asynchronous transfer mode (ATM) cell stream) fromwhich each decentralized equipment takes only the bursts (ATM cells) intended therefor; the signal transmission from the decentralized equipment to the central equipment (switching center) can be undertaken in accordance with a TDMA method in which a decentralized equiprnent transmits each burst (ATM cell) synchroni~ed with the assistance of a delay device that is set in an apparatus-associated manner by the switching center, so that it does not intersect on the common light waveguide terminal of the central equipment (switching center) with burst of other decentralized equipment (see European patent application 0 171 080, European Patent ~pplication 0 318 331, European patent application 0 337 619 and the German patent 4 014 396).
The introduction of new telecommunication systems having light waveguide central office lines is quite generally dependent on the type and scope of the telecommunications infrastructures already existing, together with the telecommunication services offered therein, and, on the demand for new broadband communication services. The potentially-greatest connection volume is thereby envisioned in the area of private households. This potential for connections, however, will only crystallize to an effective demand for connections given correspondingly-low costs of a broadband subscriber line.
In this context, it is known ffor example from Telcom Report, Vol. 11, 1988, pp. 1-5, FIG. 6) for the subscriber lines of a light waveguide telecommunication system to structurally combine the electro-optical transducer, for example a laser diode, rsspectively required for ths transmission of an optical signal with the opto-electrical transducer, for example a PIN diode, required for the reception of an optical 2~14~3~7 signal and a filter for bidirectional WDM operation to form an integrated electrical-optical/opto-electrical transmitting/receiving module for bidirectional transmission.
Such a utili~ation of a uniform module type having optimum cost-benefit components in all telecommunications of the subscriber line level of a light waveguide telecommunication system leads, on the one hand, to a corresponding cost reduction, but, on the other hand, runs contrary to the further requirement existing in this context of being able to connect an optimum plurality of decentralized telecommunication locations in the subscriber line level to a central telecummunication location. This latter situation, in particular, assumes that the system can bridge optimally-great attenuations, this fundamentally requiring the utilization of higher-quality, but more cost-intensive modules, as well as, for example, higher-power laser diodes as the electro-optical transmlssion elements and avalanche photodiodes as opto-electrical receiving elements, as intrinsically known (for example, from Telcom Report, Vol. 10, 1987, Special "Multiplex-und Leitungseinrichtungen", pp. 146-150 and 150-159).
SUMMARY OF THE INVENTION
~ he object of the present invention is to overcome the aforementioned contradictory demands in passive optical telecommunication systems.
The present invention is directed to a passive optical telecommunication system having a central telecommunication equipment and a plurality of decentralized telecommunication equipment, each of which is respectivaly connected via i~s own light waveguide central office line to an optical brancher that is connected via a light waveguide bus, either directly or at least by way of one further optical brancher, to a common light waveguide terminal of the central telecommunication equipment, whereby each of the telecommunication equipment is equipped with an electro-optical 2~ 7 transmitting element and with an opto-electrical receiving element, as well as with a filter for wavelength-division multiplex ~WDM) operation (bidirectional WDM) This telecommunication system is, according to the present invention, particularly characterized in that the electro-optical transmitting element, the opto-electrical receiving element and the filter are structurally combined into an electro-optical/opto-eiectrical transmitting/receiving module for bidirectional transmission only in the decentralized telecommunication equipment and the electro-optical transducer, the opto-electrical transducer, the opto-electrical transducer and the filter form structurally discrete components only in the central telecommunication equipment.
While retaining a high number of units (or even increasing the number of units) of a cost-effective, uniform transmitting/receiving module for the plurality of decentralized telecommunication equipment, the present invention yields the advantage of being able to utilize a high-power electro-optical transmitter, such as a laser diode having a more complex control, as well as a more sensitive electro-optical receiver, such as an avalanche photodiode in the centralized telecommunication location, and, therefore, with a correspondingly^lower number of units, and of thereof being able to increase what is referred to as the power budget in the telecommunication system, i.e. the bridgeable attenuation, by approximately 5---10 dB .
This allows the path length to be lengthened or, respectively, allows an increase in the branching factor by a factor of, for example, 2--~4, and, as seen from the point of view of the optical power, allows a doubling through quadrupling of the number of decentralized telecommunication locations that can be connected to one and the same centralized telecommunication location.
For bidirectional optical message transmission via a light waveguide between a central transmission and/or receiving station and at least one decentrali~ed transmission and/or receiving station (subscriber station), it should be noted that it is 9~7~3U
known (from the German application 3 506 715) to proceed in such a fashion that:
messages are transmitted with different bandwidths in opposite directions;
a light a first wavelength belonging to the greater bandwidth has a significantly lower optical spectral width than a light of a second - wavelength belonging to the lower bandwidth;
at least the wavelength of the second light lies in the region of the minimum of the overall dispersion of the light waveguide;
the optical spectrum of the second light radiation is shaped by an optical filter such that the first light radiated can likewise be transmitted in the region of the minimum of the overall dispersion of the light waveguide;
and a light-emitting diode generates the second light radiation and a semiconductor laser or a super-emitting diode generates the first light radiation.
Light-emitting diodes are thereby referred to as cost-effective electro-optical transmitters that can be employed in the subscriber locations. However, greater relevancy than this with the present invention is not establishsd.
It should also be noted that a bidirectional light waveguide telecommunication system for wavelength-division multiplex operation (WDM operation3 between a centralized telecommunication location and a plurality of decentralized telecommunication locations having a passive light waveguide bus network extending therebetween has already been constructed in such a manner that an electro-optical transmitting element and an opto-electrical receiving element that are designed for wavelength-division multiplex operation are only provid0d in the centralized telecommunication location, whereas a combined opto-electrical receiving/electro-optical transmitting module that is respectively free of wavelength filters, works in a time separation transmission mode and is designed ~or a transmitting light having a wavelength for whose reception the central telecommunication location is designed is provided in the decentralized telecommunication locations, whereby the combined opto-electrical receiving/electro-optical transmitting module can be formed with a laser diode used in alternation as a receiving diode or can be formed with a laser module whose monitor photodiode is utilized in al~ernation as a receiving diode (see European application 0 419 710); here, also, there is no greater relevancy than this wi~h respect to the present invention.
Further characteristics of the present invention rnay be seen from the following, more detailed explanation of an exemplary embodirnent of the invention with reference to the drawing.
BRIEF DESCRIPTION OF THE DRAWING
Other objects, features and advantages of the invention, its organization, construction and operation will be best understood ~rom the ~ollowing detailed description, taken in conjunction with the accompanying drawing, on which there is a single figure schematically illustrating a bidirectional light waveguide telecommunication system having a passive light waveguide bus network.
The bidirectional light waveguide telecommunication system shown on the clrawing is only illustrated with a scope necessary for an understanding of the invention.
DESCRIPTION OF THE PKEFERRED EMBODIMENTS
As illustrated on the drawing, a bidirectional light waveguide telecommunication system comprises a passive (preferably monomode) light waveguide bus network BPON extending between a centralized telecomrnunication location, represented by a switching center VSt, and a plurality of decentralized telecommunication equipment, represented by a plurality of remote units DU2 and DU3. In this light waveguide telecommunication system, the remote units DU are connected via a single fiber light waveguide bus OB to a common light waveguide multiplex terminal of the switching center VSt. It is here assumed ~hat the equipment-associated light waveguide central office lines OAL1,...,0ALn are connected with the appertaining light waveguide bus OB via passive, i.e. non-wavelength selective, optical branchers V1,..., Vn that, for example, are accommodated in cable branching housings and being connected thereto, in particular, either directly or via additional such branchers. For example, tandem mixers or optical directional couplers ~an be employed as optical branchers. It is also possible to provide a shared optical brancher for a plurality of equipment-associated light waveguide central office lines, as intrinsically known in the art (for example, from the European application 0 171 080 and as such, therefore, need not be set forth in greater detail herein.
A wavelength-division multiplex operation (bidirectional wavelength-division multiplexing) is provided for separating the directions in the telecommunication system outlined on the drawing in that light of a first wavelength A1 Iying, for example, 7~3 in the 1300 nm band is employed for signal transmission in the downstream direction from the centralized telecommunication location VSt to the decentralized telecommunication locations...., DU2, ~U3,...and light having a somewhat longer, second wavelength ~2 Iying, for example, in the 1500 nrn band is employed for the signal transmission in tne upstream direction from the decentralized telecommunication locations..., DU2, DU3,...to the centralized telecommunication location VSt. To this end, appropriate electro-optical transmission elements, opto-electrical receiving elements and filters for wavelength-division multiplex operation are provided in ~he switching center VSt that forms the centralized telecommunication location and in the remote units...., DU2, DU3,...that form the decentralized communication locations. As indicated on the drawing, the electro-optical transmitting element SD, the optical-electrical receiving element ED and the filter F for the wavelength-division multiplex operation (bidirectional WDM operation) are structurally combined to form an electro-optical/optical-electrical transmitting/receiving module o l e and a wavelength-selective, optical filter W form structurally discrete, separate components only in the centralized telecommunication equipment VSt. A well-known optical filter, for example as known from U.S. 4,790,616, fully incorporated herein by this reference, may be provided as the optical filter component W and with an interference beam splitter and can, therefore, be provided as the filter, a known laser module, for example as known from the Telcom ~eport Vol. 10, 1987, Special "Multiplex-und Leitungseinrichtungen", pp.
146-150, FIG. 4, can be provided as an electro-optical transducer elo and a component having an avalanche photodiode that is likewise commercially can be provided as an opto-electrical transducer o l e.
As indicated on the drawing, the signal transmission in the outlined telecommunication system from the switching center VSt downstream to the decentralized equipment..., DU2, DU3,...on the wavelength ~1 can then be undertaken in a burst stream Zdo~ for example an A~M cell stream. Such ATM cells (respectively 7~3 covering 53 bit octets) are each respectively composed of a control information field (header, 5 octets) and of a useful information field (covering 48 octets). What is referred to as the virtual path identifier (covering 16 bits) is part of the header and what is referred to as the access control field is another part of the header.
When no useful information is to be transmitted, synchronization cells having a prescribed bit pattern for synchronization ~f the decentralized equipment on the basis of the respective cell start can be mixed into the ATM cell stream Zdow~ (what is referred to as pure ATM; however, it is possible that the ATM cell stream is, in turn, embedded in a ffor example, SONET) time-frame structure having synchronization signals (overhead) appearing at specific, fixed inteNals (what is referred to as frame-structured ATM~.
Each decentralized equipment DU takes only the bursts intended therefore from the burst stream (ATM cell strearn) Zdowr~ i.e. those ATM cells in the example that are addressed in their header, preferably in the virtual path identifier thereof, with an identifier assigned to the particular decentralized equipment DU. The subdivision into header and useful information fields is shown on the drawing for four ATM cells of an ATM cell stream Zdowr~ whereby the identifiers (3, 3, 2, n) recited in the headers of these four ATM cells indicate that the first two cells, carrying useful information A and D, are intended for the decentralized equipment DU3, that the third cell, carrying a useful information C, is intended for the decentralized equipment DU2, and that the fourth cell, carrying a useful information D, is intended for decentralized equipment that can be reached via the light waveguide subscriber iine C)ALn, but which is not shown on the drawing.
In the opposite transmission direction, the signal transmission from the decentralized equipment (remote units) DU upstream to the switching center VSt on 978~
the wavelength ~2 can be undertaken in accordance with a TDMA method with bursts(potentially, ATM cells) Zup in accordance wherewith a decentralized equipment DU
transmits each burst synchronized with the assistance of a delay device ~hat is set in association with that remote equipment by the switching center VSt, so that each burst in the upstream direction is transmitted in a time slot reserved for the appertaining decentralized equipment D~J and a burst does not intersect on the shared light waveguide terminal of the centralized equipment VSt with bursts of other decentralized equipment DU. Such a synchronization of the centralized equipment DU is already known in the art and is disclosed, for example, in the European patent application 0171-080, the European patent application 0 318 331, the European patent application 0 337 619 and the German application P 4 014 396, and therefore does not have to be discussed in further detail herein.
Although I have described my invention by reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. I therefore intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of my contribution to the art.
Claims (2)
1. A passive optical telecommunication system, comprising:
a centralized telecommunication equipment for transmitting and receiving information signals;
a plurality of decentralized telecommunication equipment for transmitting and receiving information signals;
a plurality of light waveguide lines each optically coupled to a respective decentralized telecommunication equipment;
a light waveguide bus and a plurality of optical branchers each coupled to said light waveguide bus and to a respective one of said plurality of light waveguide lines;
each of said telecommunication equipment including an electro-optical transducer, an opto-electrical transducer and a filter for wavelength-division multiplexing;
said electro-optical transducer, said opto-electrical transducer and said filter structurally combined to form an electro-optical/opto-electrical transmitting/receiving module for bidirectional transmission in said decentralized telecommunication equipment; and said electro-optical transducer, said opto-electrical transducer and said filter being separate, discrete components only in said centralized telecommunication equipment.
a centralized telecommunication equipment for transmitting and receiving information signals;
a plurality of decentralized telecommunication equipment for transmitting and receiving information signals;
a plurality of light waveguide lines each optically coupled to a respective decentralized telecommunication equipment;
a light waveguide bus and a plurality of optical branchers each coupled to said light waveguide bus and to a respective one of said plurality of light waveguide lines;
each of said telecommunication equipment including an electro-optical transducer, an opto-electrical transducer and a filter for wavelength-division multiplexing;
said electro-optical transducer, said opto-electrical transducer and said filter structurally combined to form an electro-optical/opto-electrical transmitting/receiving module for bidirectional transmission in said decentralized telecommunication equipment; and said electro-optical transducer, said opto-electrical transducer and said filter being separate, discrete components only in said centralized telecommunication equipment.
2. The passive optical telecommunication system of claim 1, wherein:
said opto-electrical transducer of said centralized telecommunication equiprnent comprises an avalanche photodiode.
said opto-electrical transducer of said centralized telecommunication equiprnent comprises an avalanche photodiode.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP90116407.9 | 1990-08-27 | ||
| EP90116407 | 1990-08-27 | ||
| EP91108465.5 | 1991-05-24 | ||
| EP91108465A EP0472824A1 (en) | 1990-08-27 | 1991-05-24 | Passive optical telecommunication system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2049780A1 true CA2049780A1 (en) | 1992-02-28 |
Family
ID=26125438
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002049780A Abandoned CA2049780A1 (en) | 1990-08-27 | 1991-08-23 | Passive optical telecommunication system |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH04245824A (en) |
| CA (1) | CA2049780A1 (en) |
| HU (1) | HUT60416A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009137909A1 (en) * | 2008-05-14 | 2009-11-19 | Peter Schmelcher | Remote utility metering using a passive optical network |
-
1991
- 1991-08-23 JP JP3237019A patent/JPH04245824A/en not_active Withdrawn
- 1991-08-23 CA CA002049780A patent/CA2049780A1/en not_active Abandoned
- 1991-08-26 HU HU912790A patent/HUT60416A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009137909A1 (en) * | 2008-05-14 | 2009-11-19 | Peter Schmelcher | Remote utility metering using a passive optical network |
Also Published As
| Publication number | Publication date |
|---|---|
| HU912790D0 (en) | 1992-08-28 |
| JPH04245824A (en) | 1992-09-02 |
| HUT60416A (en) | 1992-08-28 |
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