ABDUL KADIR, Muhammad, Zamzuri (No. 3, Jalan 7/11Seksyen 7,Taman Lestari Putra, Bandar Putra Permai, Selangor, 43400, MY)
RAHMAN, Zainuddin (No. 22, Jalan 7/5ASeksyen 7, Bandar Baru Bangi, Selangor, 43650, MY)
KHYASUDEEN, Muhammad, Fahmy (No. 8, Taman Puspa Kencana Alor Setar, Kedah, 05640, MY)
MOHD RAMLY, Mohd., Rizal (Lorong 10A, Kampung Bahagia Teluk Intan, Perak, 36000, MY)
MUHAMED, Ahmad, Hishamuddin (No. 3, Jalan 2/11Desa Saujana,Sungai Merab, Kajang, Selangor, 43000, MY)
ISMAIL, Muhamad, Noh (No. 13, Jalan Pinggira Putra 5/38Desa Pinggiran Putra,Sungai Merab, Kajang, Selangor, 43000, MY)
ISMAIL, Ummi, Supya (No.21, Jalan 4/9GSeksyen 4 Tambahan, Bandar Baru Bangi, Selangor, 43650, MY)
ABDUL KADIR, Muhammad, Zamzuri (No. 3, Jalan 7/11Seksyen 7,Taman Lestari Putra, Bandar Putra Permai, Selangor, 43400, MY)
RAHMAN, Zainuddin (No. 22, Jalan 7/5ASeksyen 7, Bandar Baru Bangi, Selangor, 43650, MY)
KHYASUDEEN, Muhammad, Fahmy (No. 8, Taman Puspa Kencana Alor Setar, Kedah, 05640, MY)
MOHD RAMLY, Mohd., Rizal (Lorong 10A, Kampung Bahagia Teluk Intan, Perak, 36000, MY)
MUHAMED, Ahmad, Hishamuddin (No. 3, Jalan 2/11Desa Saujana,Sungai Merab, Kajang, Selangor, 43000, MY)
ISMAIL, Muhamad, Noh (No. 13, Jalan Pinggira Putra 5/38Desa Pinggiran Putra,Sungai Merab, Kajang, Selangor, 43000, MY)
| THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. An arrangement for converting wavelengths for bi-directional Wavelength Division Multiplexing (xWDM), the arrangement comprising: 5 at least one first transmitting system; at least one first wavelength converter, each first wavelength converter adapted to convert an optical signal from one of the first transmitting systems to a first converted signal, the conversion being such that the wavelength of each first converted signal conforms to a xWDMo standard; and a bi-directional xWDM module adapted to direct each first converted signal in a first direction. 2. An arrangement as claimed in claim 1 , the arrangement further 5 comprising: at least one second transmitting system; and at least one second wavelength converter, each second wavelength converter adapted to convert an optical signal from one of the second transmitting systems to a second converted signal, the conversion being o such that the wavelength of each second converted signal conforms to a xWDM-standard, wherein the bi-directional xWDM module is further adapted to direct each second converted signal in a second direction opposite to the first direction. 5 3. An arrangement as claimed in claim 2, the arrangement further comprising: at least one second receiving system; and at least one fourth wavelength converter, each fourth wavelength 0 converter adapted to convert one of the second converted signals from the bi-directional WDM module to a fourth converted signal, the conversion being such that the wavelength of each fourth converted signal conforms to a wavelength used in one of the second receiving systems. 5 4. An arrangement as claimed in anyone of claims 1 to 3, the arrangement further comprising: at least one first receiving system; and at least one third wavelength converter, each third wavelength converter adapted to convert one of the first converted signals from the bidirectional WDM module to a third converted signal, the conversion being such that the wavelength of each third converted signal conforms to a wavelength used in one of the first receiving systems. 5. An arrangement as claimed in any one of the preceding claims, wherein at least one of the converters comprises a receiver circuit for converting an optical signal to an electrical signal; and a transmitter circuit for converting the electrical signal to a converted signal. 6. An arrangement as claimed in any one of the preceding claims, the arrangement further comprising an optical protection switch for protecting the bi-directional xWDM module. 7. An arrangement as claimed in any one of the preceding claims, wherein at least one of the transmitting systems comprises means for processing a signal following a standard selected from the group including: Digital Loop Carrier (DLC)1 Digital Subscriber Lines (xDSL), Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH). 8. An arrangement as claimed in claim 3 or claim 4, wherein at least one of the receiving systems comprises means for processing a signal following a standard selected from the group including: Digital Loop Carrier (DLC), Digital Subscriber Lines (xDSL), Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH). 9. An arrangement as claimed in any one of the preceding claims, wherein at least one of the transmitting systems is a Serving Area Interface (SAI) cabinet. 10. An arrangement as claimed in claim 3, claim 4 or claim 8, wherein at least one of the receiving systems is a Serving Area Interface (SAI) cabinet. 11. An arrangement as claimed in any one of the preceding claims, wherein at least one of the transmitting systems is a central office. 12. An arrangement as claimed in claim 3, claim 4 or claim 8, wherein at least one of the receiving systems is a Serving Area Interface cabinet. 5 13. A method for converting wavelengths for bi-directional Wavelength Division Multiplexing (xWDM), the method comprising the steps of: converting at least one optical signal to at least one first converted signal, the conversion being such that the wavelength of each first convertedo signal conforms to a xWDM-standard; and directing each first converted signal in a first direction in a bidirectional xWDM module. 14. A method as claimed in claim 13, the method further comprising the5 steps of: converting at least one optical signal to at least one second converted signal, the conversion being such that the wavelength of each second converted signal conforms to a xWDM-standard; and directing each second converted signal in a second direction opposite0 to the first direction in the bi-directional xWDM module. 15. A method as claimed in claim 14, the method further comprising the step of: converting each second converted signal to a fourth converted signal, 5 the conversion being such that the wavelength of each fourth converted signal conforms to a wavelength used in a second receiving system. 16. A method as claimed in any one claims 13 to 15, the method further comprising the step of: o converting each first converted signal to a third converted signal, the conversion being such that the wavelength of each third converted signal conforms to a wavelength used in a first receiving system. 17. A method as claimed in any one of the claims 13 to 16, the method 5 further comprising the step of: protecting the bi-directional WDM module. 18. A method as claimed in any one of the claims 13 to 17, wherein each optical signal comprises data routed from a system following a standard selected from the group including: Digital Loop Carrier (DLC), Digital Subscriber Lines (xDSL), Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH). 19. A method as claimed in claim 16, wherein each third converted signal comprises data routed from a system following a standard selected from the group including: Digital Loop Carrier (DLC), Digital Subscriber Lines (xDSL), Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH). 20. A method as claimed in claim 15, wherein each fourth converted signal comprises data routed from a system following a standard selected from the group including: Digital Loop Carrier (DLC), Digital Subscriber Lines (xDSL), Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH). |
Field of the invention:
The present invention relates to an arrangement and a method for converting wavelengths for bi-directional Wavelength Division Multiplexing (xWDM).
Background:
First developed in the 1970s, optical fiber communications have revolutionized the telecommunications industry. Because of its advantages over electrical transmission, the use of optical fiber has largely replaced copper wire in telecommunications networks.
There has been considerable technological advancement in optical fiber communications since the 1970s. One major breakthrough is Wavelength Division Multiplexing (xWDM), a technology for using optical fibers so that they may simultaneously transmit a number of channels using a number of different wavelengths. There are now many examples in the literature describing how xWDM can be used not only to increase capacity, but also to improve reliability, scalability and functionality. Despite this, xWDM has not been widely implemented.
The present invention is intended to enable xWDM technology to be used in additional circumstances.
Summary of the Invention:
According to a first aspect of the present invention, there is provided an arrangement for converting wavelengths for bi-directional Wavelength Division Multiplexing (xWDM), the arrangement comprising: at least one first transmitting system; at least one first wavelength converter, each first wavelength converter adapted to convert an optical signal from one of the first transmitting systems to a first converted signal, the conversion being such that the wavelength of each first converted signal conforms to a xWDM standard; and a bi-directional xWDM module adapted to direct each first converted signal in a first direction.
In an embodiment, the arrangement further comprises: at least one second transmitting system; and at least one second wavelength converter, each second wavelength converter adapted to convert an optical signal from one of the second transmitting systems to a second converted signal, the conversion being such that the wavelength of each second converted signal conforms to a xWDM-standard, wherein the bi-directional xWDM module is further adapted to direct each second converted signal in a second direction opposite to the first direction.
In an embodiment, the arrangement further comprises: at least one second receiving system; and at least one fourth wavelength converter, each fourth wavelength converter adapted to convert one of the second converted signals from the bi-directional WDM module to a fourth converted signal, the conversion being such that the wavelength of each fourth converted signal conforms to a wavelength used in one of the second receiving systems.
In an embodiment, the arrangement further comprises: at least one first receiving system; and at least one third wavelength converter, each third wavelength converter adapted to convert one of the first converted signals from the bidirectional WDM module to a third converted signal, the conversion being such that the wavelength of each third converted signal conforms to a wavelength used in one of the first receiving systems.
In an embodiment, at least one of the converters comprises a receiver circuit for converting an optical signal to an electrical signal; and a transmitter circuit for converting the electrical signal to a converted signal. In an embodiment, at least the arrangement further comprises an optical protection switch for protecting the bi-directional xWDM module. In an embodiment, at least one of the transmitting systems comprises means for processing a signal following a standard selected from the group including: Digital Loop Carrier (DLC), Digital Subscriber Lines (xDSL),
Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH).
In an embodiment, at least one of the receiving systems comprises means for processing a signal following a standard selected from the group including: Digital Loop Carrier (DLC), Digital Subscriber Lines (xDSL),
Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH).
In an embodiment, at least one of the transmitting systems is a Serving Area Interface (SAI) cabinet.
In an embodiment, at least one of the receiving systems is a Serving Area Interface (SAI) cabinet.
In an embodiment, at least one of the transmitting systems is a central office.
In an embodiment, at least one of the receiving systems is a Serving Area Interface cabinet.
According to a second aspect of the present invention, there is provided a method for converting wavelengths for bi-directional Wavelength Division Multiplexing (xWDM), the method comprising the steps of: converting at least one optical signal to at least one first converted signal, the conversion being such that the wavelength of each first converted signal conforms to a xWDM-standard; and directing each first converted signal in a first direction in a bidirectional xWDM module.
In an embodiment, the method further comprises the steps of: converting at least one optical signal to at least one second converted signal, the conversion being such that the wavelength of each second converted signal conforms to a xWDM-standard; and directing each second converted signal in a second direction opposite to the first direction in the bi-directional xWDM module.
In an embodiment, the method further comprises the step of: converting each second converted signal to a fourth converted signal, the conversion being such that the wavelength of each fourth converted signal conforms to a wavelength used in a second receiving system.
In an embodiment, the method further comprises the step of: converting each first converted signal to a third converted signal, the conversion being such that the wavelength of each third converted signal conforms to a wavelength used in a first receiving system.
In an embodiment, the method further comprises the step of: protecting the bi-directional WDM module.
In an embodiment, each optical signal comprises data routed from a system following a standard selected from the group including: Digital Loop Carrier (DLC), Digital Subscriber Lines (xDSL), Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH).
In an embodiment, each third converted signal comprises data routed from a system following a standard selected from the group including: Digital Loop Carrier (DLC), Digital Subscriber Lines (xDSL), Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH).
In an embodiment, each fourth converted signal comprises data routed from a system following a standard selected from the group including: Digital Loop Carrier (DLC), Digital Subscriber Lines (xDSL), Multiservice Access Nodes (MSAN) or Synchronous Digital Hierarchy (SDH).
Brief description of the drawings:
Embodiments, incorporating all aspects of the invention, will now be described by way of example only with reference to the accompanying drawings in which:
Figure 1 is a schematic view of an arrangement for bi-directional Wavelength Division Multiplexing (xWDM) for optical communications according to a first embodiment of the present invention;
Figure 2 is a schematic view of an arrangement for bi-directional Wavelength Division Multiplexing (xWDM) for optical communications according to a second embodiment of the present invention; and
Figure 3 is a schematic view of an arrangement for bi-directional Wavelength Division Multiplexing (xWDM) using an optical protection switch according to a third embodiment of the present invention.
Figure 4 is a schematic view of an arrangement for bi-directional Wavelength Division Multiplexing (xWDM) using an optical protection switch according to a fourth embodiment of the present invention.
Figure 5 is a schematic view of an optical protection switch used in the third and fourth embodiments of the present invention.
Detailed description:
Figure 1 illustrates an arrangement 100 for bi-directional Wavelength Division Multiplexing (xWDM) according to a first embodiment of the present invention.
A plurality of transmitting and receiving systems 200, 210, 220, 230, 240 and 250 (also sometimes called "transceivers") are located at two ends of a communication system. Each transmitting system is arranged so as to communicate with a receiving system located on the other side of the communication system. In this embodiment, all transmitting systems are also receiving systems. However, it is envisaged that in some embodiments, one or more of the transmitting and/or receiving systems may operate only to transmit or receive only.
In one example, a transmitting and receiving system may be a Digital Loop Carrier (DLC) remote terminal installed in a Service Area Interface (SAI) cabinet. Such a device reduces the labour and complexity of installing individual local loops from the customer to the Central Office (CO). Optical fibers can be used to connect the whole system from a CO to the remote terminals needed for each loop.
In another example, Digital Subscriber Line Access Multiplexers (DSLAM) 5 can be installed in SAI cabinets to gain access to the benefits provided by the link from the SAI cabinet to the CO. This takes advantage of the growth in popularity of Digital Subscriber Line (xDSL) technology. In addition, DLC remote terminals can sometimes be integrated together with these DSLAMs, both systems then taking advantage of the digital transmission link from theo DLC to the CO and the benefits provided by shorter metallic loops used with DLC systems.
In yet another example, there may be an installation of a Multi Service Access Node (MSAN) in a SAI cabinet. The MSAN allows customers to5 connect their telephone lines to the central office thereby providing telephony and broadband services such as xDSL all from a single platform. Prior to the deployment of MSANs, providers typically had separate equipment including DSLAMs to provide the various types of services to customers. Integrating all services on a single node can be more cost effective and may more quickly o provide new services to customers.
In Figure 1 , each transmitting system generates an output optical signal but not one which is compatible with an xWDM standard. Similarly, each receiving system is able to receive an optical signal but not one which is 5 compatible with an xWDM standard. In an alternative embodiment, one or more of the transmitting and/or receiving systems may be compatible with an xWDM standard.
The optical signals generated at each transmitting system 200, 210, 220, o 230, 240 and 250 are transmitted via uni-directional links to receiver circuits
500, 510, 520, 530, 540 and 550. These optical fiber links are usually made up of Time Division Multiplexing (TDM) links, such as Synchronous Digital Hierarchy (SDH) or Plesiochronous Digital Hierarchy (PDH) links (i.e. T1 , E1 , T3 and E3). 5
Each receiver circuit 500, 510, 520, 530, 540 and 550 converts a respective optical signal received from the transmitting system to an electrical signal. The electrical signals generated are then passed on to transmitter circuits 600, 610, 620, 630, 640 and 650. The role of each transmitter circuit is to convert the electrical signals to optical signals such that each wavelength is compatible to an xWDM standard. In one embodiment, these may be wavelengths corresponding to the Dense Wavelength Division Multiplexing (DWDM) standard. In another embodiment, these may be wavelengths corresponding to the Coarse Wavelength Division Multiplexing (CWDM) standard. The difference between the two different xWDM standards being that CWDM systems can provide up to 16 channels in the 3rd transmission window (C-band) of silica fibers around 1550 nm whereas DWDM uses the same transmission window but with denser channel spacing to provide up to 40 channels at 100 GHz spacing or up to 80 channels with 50 GHz spacing.
In an embodiment, the receiver circuit and the transmitter circuit can be combined into a single device, commonly referred to as a wavelength converting transponder or an O-E-0 (Optical-Electrical-Optical) transponder. In another embodiment, one could use an optical transponder. This removes the need for electrical conversions.
In Figure 1 , the optical signals (now compatible with a particular xWDM standard such as CWDM or DWDM) are transmitted to a multiplexer 400 or 410 which combines the different optical signals into one single optical signal. A circulator 440 or 450 then circulates this signal through an xWDM optical fiber 460 to another circulator 450 or 440. In this embodiment, the wavelengths of the output xWDM optical signals from the transmitter circuits 600, 610, 620, 630, 640 and 650 can be carefully selected so that they are all different so as to maximise bi-directional transmission capacity between the two circulators. In this case, the wavelengths of the signals combined at multiplexer 400 are λ-u, A 2x ... λ nx and the wavelengths of the signals combined at multiplexer 410 are λi y , λ 2y ... λ ny .
After passing through the optical fiber, the circulator 450 or 440 then circulates the core signal to a demultiplexer 420 or 430 which demultiplexes the core signal into a plurality of optical signals. In this embodiment, the wavelengths of the signals that are demultiplexed correspond exactly with those multiplexed. This need not be the case. In another embodiment, the wavelengths of the multiplexed and demultiplexed signals can be different. The arrangement including multiplexers 400 and 410, demultiplexers 420 and 430, circulators 440 and 450, and the xWDM optical fiber 460 is sometimes referred to as a bi-directional xWDM module. This module permits the transmission of a first xWDM signal in one direction and a second xWDM signal in a direction opposite to the first xWDM signal, thereby providing bi-directional communication without the need for two optical fibers.
After demultiplexing, each of the signals from the demultiplexers 430 and 420 are then transmitted to receiver circuits 700, 710, 720, 730, 740 and 750 which converts each xWDM compatible signal from the demultiplexer into an electrical signal. These signals are passed on to transmitter circuits 800, 810, 820, 830, 840 and 850. The role of these transmitter circuits is to convert the electrical signals to optical signals in a way so that the wavelength of each output optical signal corresponds to the particular receiving system. Each signal is then transmitted via uni-directional links to the corresponding receiving systems 200, 210, 220, 230, 240 and 250.
Figure 2 illustrates an arrangement 110 for bi-directional Wavelength Division Multiplexing (WDM) for optical communications according to a second embodiment of the present invention.
In this embodiment, there are a plurality of transmitting and receiving systems 300, 310, 320, 330, 340 and 350. Each of these transmitting systems is unable to transmit a optical signal that is compliant with an xWDM standard but each of the receiving system is capable of receiving a xWDM compatible optical signal.
The path from each transmitting system 300, 310, 320, 330, 340 and 350 to the respective demultiplexer 420 or 430 is substantially the same as that for figure 1. However, in this embodiment, there is no need to convert the wavelengths of the signals into a different wavelength as the receiving systems are capable of receiving them.
Figure 3 illustrates an arrangement 120 for bi-directional Wavelength Division Multiplexing (WDM) according to a third embodiment of the present invention. In this embodiment, the arrangement is similar to that of Figure 1 but that an optical protection switch 470 is added to protect the system when the working optical fiber is broken.
Figure 4 illustrates an arrangement 130 for bi-directional Wavelength
Division Multiplexing (WDM) according to a fourth embodiment of the present invention.
In this embodiment, the arrangement is similar to that of Figure 1 but that an optical protection switch 470 is added to protect the system when the working optical fiber is broken.
Figure 5 illustrates the optical protection switch 470 that is implemented with the third or fourth embodiments of the present invention.
Note that other arrangement or types of optical protection switch can also be used.
It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention, in particular that various features of the above embodiments can be combined to form further embodiments.
In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
It is to be understood that the prior art publication referred to herein does not constitute an admission that the publication forms a part of the common general knowledge in any country.