The present invention relates to the reconfigurable optical add-drop multiplexer (ROADM) and optical cross technology in the field of optical communications, and more especially, to a method and system for realizing multi-directional ROADM.
Currently, the DWDM (Dense Wavelength Division Multiplexing) equipment has been widely applicable to the backbone network, the local and metropolitan core networks, and the DWDM equipment network topology also transits from simple point-to-point to the ring network and two ring intersection, and it ultimately will be applied to the lattice network and mesh network. The service type transits from the Time Division multiplex (TDM) service based circuit switch services to Internet Protocol (IP) based data services. Due to the uncertainty of the service development and the increase of estimation difficult), in the early stage, there are requirements for the equipment intelligence, and when the network topology as well as the service distribution changes, it is expected that the service scheduling capability is implemented quickly and flexibly to adapt to the change of the networking and the service distribution.
Similar to the method that the synchronous digital hierarchy (SDH) equipment exchanges and schedules the VC-4, the network intelligence requests the DWDM equipment to provide wavelength based configurable function, that is, the wavelength configurable optical add-drop multiplexing function to flexibly achieve the wavelength add-drop multiplexing function and the remote configuration. The ROADM can achieve any point to any point connection without manual deployment or implement the Add and Drop of single wavelength as well as the straight-through configuration. The ROADM technology can be used to increase the flexibility of the Wavelength Division Multiplexing (WDM) network, to enable the operators to remotely and dynamically control the wavelength transmission path, which effectively reduce the operator's operating and maintenance costs. With the development of the network scale and the diversity of service types, it is required to provide the multi-directional intelligent ROADM system that can implement the service broadcast function.
There are multiple methods for achieving the ROADM function, comprising the optical switch array based Micro-Electro-Mechanical Systems (MEMS) approach and the current novel optical device based implementation approach. Wherein, the novel optical devices mainly include the wavelength blocker (WB) and the wavelength selective switch (WSS).
At present, the wavelength selective switch is utilized to achieve the structure of reconfigurable optical add-drop multiplexer with the wavelength independence and the direction independence, which is shown in
The technical problem to be solved in the present invention is to provide a method and system for implementing multi-directional reconfigurable OADM to overcome the shortcomings that the WSS based multi-directional ROADM equipment is expensive and the Add and Drop of the same wavelength are restricted.
To solve the aforementioned problem, the present invention provides a method for implementing multi-directional reconfigurable optical add-drop multiplexer, comprising:
Amplifying optical signals transmitted from N directions respectively, and then performing demultiplexing respectively, dividing optical signals in each direction into M groups of optical signals with different wavelengths, and then transmitting N groups of demultiplexed optical signals with same wavelength in each direction to the same optical crossbar switch, and each optical crossbar switch receiving N groups of optical signals with same wavelength; each optical crossbar switch outputting input optical signals from corresponding output interfaces according to configuration information; wherein M and N are both positive integers.
The aforementioned method might also have the following feature:
the step of transmitting N groups of demultiplexed optical signals with same wavelength in each direction to the same optical crossbar switch comprises: inputting a kth group of demultiplexed optical signals in each direction to a kth optical crossbar switch, wherein 1≦k≦M.
The aforementioned method might also comprise:
After an Add wavelength tunable transmitter completes wavelength tuning of a service access signal, dividing optical signals into L directions and inputting the signals to L Add H×H optical crossbar switches respectively; the L Add H×H optical crossbar switches inputting the optical signals to the M optical crossbar switches via M groups of output ports of optical crossbar switches, where each group is composed of R/2 ports; wherein L is a positive integer.
The aforementioned method might also comprise: when the output interfaces outputting the optical signals correspond to a straight-through direction, the output optical signals are multiplexed and then transmitted along the straight-through direction.
The aforementioned method might also comprise:
when the output interface outputting the optical signals corresponds to Drop, after an Drop optical crossbar switch connecting with the output interface receives the optical signals, it exchanging the optical signals to a corresponding direction, and after multiplexed into one path of signal, selecting one path of signal for output by a filtering selection and receiving unit.
The present invention also provides a system for implementing multi-directional reconfigurable OADM, comprising: N Optical Preamplifiers (OPAs), N demultiplexing units and M optical crossbar switches;
said N OPAs are respectively configured to: amplify and send received optical signals from each corresponding direction to a corresponding demultiplexing unit;
the demultiplexing units are configured to: divide the received and amplified optical signals into M groups of optical signals with different wavelengths, up to x optical signals in each group;
each demultiplexing unit comprises at least Mxx output interfaces, and every x output interfaces connect with x input interfaces of one optical crossbar switch, and optical signals output by output interfaces in each demultiplexing unit connected with the input interfaces of each optical crossbar switch have the same wavelength;
each optical crossbar switch is configured to: exchange input optical signals to a corresponding output interface in accordance with configuration information; wherein M, N and x are all positive integers.
The aforementioned system might also comprise N multiplexing units;
every x output interfaces in said each optical crossbar switch are connected with one multiplexing unit;
said multiplexing unit is configured to: multiplex and output the optical signals received from the corresponding output interface.
The aforementioned system might also have the following feature:
a kth group of output ports of said each demultiplexing unit are connected with a kth crossbar switch, and a kth group of output ports in said each optical crossbar switch are connected with a kth multiplexing unit; wherein, 1≦k≦M.
The aforementioned system might also comprise: P Add wavelength tunable transmitters, P first splitters and L Add optical crossbar switches;
said P Add wavelength tunable transmitters are respectively connected with said P first splitters, and said Add wavelength tunable transmitters are configured to: tune a wavelength of received service access signal and then send the signal to a corresponding first splitter;
each of said first splitters comprises at least L output interfaces, and each interface is connected with one said Add optical crossbar switch, and the Add optical crossbar switches connected with the output interfaces in the same direction are same; said first splitter is configured to: divide the received optical signals into L directions and respectively input the signals to L said Add optical crossbar switches;
R×M/2 output ports in the L Add optical crossbar switches are connected with the input interfaces of the M optical crossbar switches, and every R/2 output ports are connected with one said optical crossbar switch; the Add optical crossbar switch is configured to: exchange the input optical signals to the corresponding output interface for output according to the configuration information; wherein, L is a positive integer.
The aforementioned system might also comprise: L Drop optical crossbar switches, P second splitters and P receiving units;
R×M/2 input ports in the L Drop optical crossbar switches are connected with the R×M/2 output interfaces of the M optical crossbar switches, and a pth output signal of each Drop optical crossbar switch is connected with a pth second splitter, and the Drop optical crossbar switch is configured to: exchange the received optical signals to the corresponding output port for output according to the configuration information thereof; wherein 1≦p≦H;
each second splitter is connected with one receiving unit, and the second splitter is configured to: after multiplexing the received optical signals into one path of signal, output said one path of signal to the receiving unit which is connected with the second splitter;
said receiving unit is configured to: receive optical signals.
The method and system provided in the present invention have the following advantages: the design of the method is simple, and the equipment can be easily implemented; the number of input and output ports of the optical crossbar switch can be flexibly selected: when there are a relatively large number of line directions, it has a significant cost advantage.
The technical solution of the present invention will be described in further detail in the following in combination with the accompanying drawings and the specific embodiments.
The basic idea of the method in the present invention is: after amplifying optical signals transmitted from N directions, the optical signals are demultiplexed, and the optical signals in each direction are divided into M groups of optical signals with different wavelengths, and then N groups of demultiplexed optical signals with the same wavelength in each direction are transmitted to the same optical crossbar switch, and each optical crossbar switch receives N groups of the optical signals with the same wavelength; each optical crossbar switch exchanges the input optical signals to the corresponding output interface according to the configuration information; wherein, M and N are both positive integers.
In addition, when the output interface outputting the optical signals corresponds to the straight-through direction, the output optical signals are multiplexed and then transmitted in the straight-through direction.
Preferably, the kth group of demultiplexed optical signals in each direction are input to the kth optical crossbar switch, wherein 1≦k≦M.
After the Add wavelength tunable transmitter completes wavelength tuning of the service access signal, the splitter splits the optical signals into L portions and respectively inputs the signals to the L Add H×H optical crossbar switches; in the L×H output ports of L optical crossbar switches, (R*M)/2 ports can be randomly selected and divided into M portions which are respectively input to the M R×R optical crossbar switches. Therefore, the Add from any of p tunable transmitters to any direction with any wavelength can be achieved.
Correspondingly, the (R*M)/2 signals in the M optical crossbar switches are input to the input ports of L Drop optical crossbar switches. Preferably, the optical signal at the first output port of each Drop optical crossbar switch is input to the first L×1 splitter, and the second output signal is input to the second L×1 splitter, and so on, and the pth output signal is input to the pth L×1 splitter. The optical signals output by the L×1 splitters 1˜p are respectively input to the 1˜pth receiving units RXs. Therefore, the Drop from any direction with any wavelength to any of the p receiving units can be achieved.
The system in the present invention also comprises: N Optical Preamplifiers (OPAs), N demultiplexing units and M optical crossbar switches, and N multiplexing units;
the N OPAs are respectively used to receive the optical signals from each corresponding direction, and divide the optical signals into M groups of optical signals with different wavelengths, up to x optical signals for each group; each OPA has at least M groups of output ports, and each group has x output interfaces, every x output interfaces are connected with x input interfaces of one optical crossbar switch, and the optical signals output by the output interfaces of each OPA connected with the input interfaces of each optical crossbar switch have the same wavelength;
every x output interfaces of each optical crossbar switch is connected with one multiplexing unit; and is used to exchange the input optical signals to the specified output interface according to the configuration information, and output the optical signals from the output interface to the multiplexing unit in the corresponding direction;
said multiplexing unit is used to multiplex and output the received optical signals.
Wherein, M, N and x are all positive integers.
Preferably, the kth group of output ports of each demultiplexing unit is connected with the kth crossbar switch, wherein 1≦k≦M. The kth group of output ports in each crossbar switch can be connected with the kth multiplexing unit.
The ROADM equipment provided in the present invention comprises:
1) Optical preamplifiers in the directions 1˜N;
2) q-channel demultiplexing units in the line directions of the directions 1˜N;
3) the R×R optical crossbar switches 1˜M;
4) q-channel multiplexing units in the line directions of the directions 1 to N;
5) Optical Booster Amplifiers (OBA) in the directions 1˜N;
6) The Add/Drop H×H optical crossbar switches 1˜2*L;
7) The 1×L splitter of the Add units 1˜p;
8) The L×1 splitters of the Drop units 1˜p;
9) Tunable Add transmitter TX;
10) Filtering selection and receiving unit RX;
11) Connection optical fiber between various units.
The present invention uses the method of wavelength grouping and crossing, and the q channels in each direction are divided into M groups, and it is assumed that each group has x channels. The connection relationship of the line direction is shown in
(1) the optical preamplifiers in the directions 1˜N respectively receive the input signals in the corresponding directions, and amplify the optical signals to ensure the straight-through power and the Drop receiving power in the direction;
(2) the amplified optical signals in each direction are input to the multiplexing unit in each direction. After the demultiplexing unit, all wavelengths are separated into individual optical channels. The optical signals of the first group of wavelengths (1˜x channels) in each direction are accessed to the input ports of the first optical crossbar switch, and the optical signals of the second group of wavelengths ((x+1)-2x channels) in each direction are accessed to the second optical crossbar switch, and so on, the optical signals of the Mth group of wavelengths are accessed to the Mth optical crossbar switch.
(3) the optical signals output by the optical crossbar switches are connected to the multiplexing units in the directions 1˜N in accordance with the same grouping method as the input grouping method. N*x output ports of each optical crossbar switch are extracted and divided into N groups, the first group of the output ports of each optical crossbar switch are accessed to the multiplexing unit in the direction 1, the second group of the output ports are accessed to the multiplexing unit in the direction 2, and so on, and the Nth group of the output ports are accessed to the multiplexing unit in the direction N;
(4) the optical signals output by the multiplexing units in the directions 1˜N are accessed to the optical booster amplifiers in the directions 1˜N to achieve the amplification of the optical signals in the direction so as to ensure the transmission performance.
The Add unit is composed of the tunable Add transmitters TX, the 1×L splitters, the Add H×H optical crossbar switches, and part of input ports of the R×R optical crossbar switches.
The connection relationship of the Add unit is as follows: after the Add wavelength tunable transmitters complete the wavelength tuning of the service access signal, the signal is split by p 1×L splitters into L portions which are respectively input to the L Add H×H optical crossbar switches. In the L*H output ports of the L optical crossbar switches, (R*M)/2 ports are randomly selected and divided into M portions which are respectively input to the M R×R optical crossbar switches. Thus the Add from any of the p tunable transmitters to any direction with any wavelength can be achieved.
The Drop unit is composed of the receiving units RX, the L×1 splitter, the Drop H×H optical crossbar switches, and part of the output ports of the R×R optical crossbar switch.
The connection relationship of the Drop unit is as follows: the R/2 output optical signals of each of the 1˜M R×R optical crossbar switches are counted up to (R*M)/2 signals which are input to the input ports of the L Drop H×H optical crossbar switches. The optical signal at the first output port of each Drop H×H optical crossbar switch is input to the first Lxl splitter, the second output signal is input to the second L×1 splitter, and so on, and the pth output signal is input to the pth L×1 splitter. The optical signals output by the L×1 splitters 1˜p are respectively input to the 1˜p receiving units RX. Thus the Drop from any direction with any wavelength to any of p receiving units can be achieved.
The method for designing the multi-directional ROADM equipment given in the present invention is as follows: the number of given directions is N, the number of channels in each direction is q, and the numbers of ports of optical crossbar switch are R and H, and the number of Add/Drop channels is p.
When R>2*N and p<=H are met, the equipment can be realized. With the following formula, the numbers of the R×R and H×H optical crossbar switches M and L and the number of wavelengths x in each wavelength group can be acquired, and when there is decimal, the result can be rounded up.
x=R/(2*N) (1)
M=q/x (2)
L=N*q/H (3)
After each parameter of the equipment is determined, the equipment can be constructed according to the aforementioned connection relationship.
The 4-directional ROADM equipment can be designed according to the method given in the present invention, and there are 80 wavelengths in each direction, and the 128×128 optical crossbar switch is used, then:
the number of Add/Drop channels: p=128;
the number of wavelengths in each group: x=R/(2*N)=128/(2*4)=16
the number of optical switches in the line direction: M=q/x=80/16=5.
the number of optical switches in the Add/Drop direction: L=N*q/H=4*80/128=3
The equipment for implementing a reconfigurable optical add-drop multiplexer (ROADM) according to the present invention comprises:
1) the optical preamplifiers (OPAs) in the directions 1˜4;
2) the 80-channel demultiplexing units in the line directions of the directions 1˜4:
3) the 128×128 optical crossbar switches 1˜5;
4) the 80-channel multiplexing units in the line directions of the directions 1˜4:
5) the optical booster amplifiers (OBAs) in the directions 1˜4;
6) the Add/Drop 128×128 optical crossbar switches 1˜6;
7) the 1×3 splitters of the Add channels 1˜128;
8) the 3×1 splitters of the Drop channels 1˜128;
9) the tunable Add transmitters TX of the Add channels 1˜128;
10) the filtering selection and receiving units RX of the Drop channels 1˜128;
11) the connection optical fiber between various units.
The specific connection relationship is shown in
The optical preamplifiers in the directions 1˜4 respectively receive the input signals in the corresponding directions and amplify the optical signals to ensure the straight-through power and the Drop receiving power in the direction.
The optical signals amplified by the optical preamplifiers in the directions 1˜4 are input to the demultiplexing units in the corresponding directions. After the demultiplexing units, the 80 wavelengths in each direction are split into individual optical channels. The optical signals of the first group of wavelengths (1˜16 channels) in each direction are accessed to the input port of the first optical crossbar switch, and the optical signals of the second group of wavelengths (17˜32 channels) are accessed to the second optical crossbar switch, and so on, the optical signals of the 5th group of wavelengths (65˜80 channels) are accessed to the 5th optical crossbar switch.
The optical signals output by the optical crossbar switches are connected to the multiplexing units in the directions 1˜4 in accordance with the same grouping method as the input grouping method. 64 output ports of each optical crossbar switch are extracted and divided into 4 groups, the first group of each optical crossbar switch is accessed to the multiplexing unit in the direction 1, the second group is accessed to the multiplexing unit in the direction 2, and so on, and the 5th group is accessed to the multiplexing unit in the direction 5;
The optical signals output by the multiplexing units in the directions 1˜4 are accessed to the optical booster amplifiers in the directions 1˜4 to achieve the amplification of the optical signals in these directions so as to ensure the transmission performance.
The Add unit is composed of the tunable Add transmitters TX, the 1×3 splitters, the Add 128×128 optical crossbar switches, and part of the input ports of the optical crossbar switches in the line direction.
The connection relationship of the Add unit is as follows: after the Add wavelength tunable transmitters complete the wavelength tuning of a service access signal, the signal is split by the 128 1×3 splitters into 3 portions which are respectively input to 3 Add 128×128 optical crossbar switches. At the 384 output ports of the 3 optical crossbar switches, 320 ports are randomly selected and divided into 5 portions that are respectively input to the optical crossbar switches in the five line directions. Thus the Add from any of the 128 tunable transmitters to any direction with any wavelength can be achieved.
The Drop unit is composed of the filtering selection and receiving units RX, the 3×1 splitters, the Drop 128×128 optical crossbar switches, and part of the output ports of the optical crossbar switch in the line direction.
The connection relationship of the Drop unit is as follows: the 64 output optical signals of each of the optical crossbar switches in the 5 line directions are counted up to 320 signals which are input to the input ports of the 3 Drop 128×128 optical crossbar switches. The optical signal at the first output port of each Drop 128×128 optical crossbar switch is input to the first 3×1 splitter, the second output signal is input to the second 3×1 splitter, and so on, and the 128th output signal is input to the 128th 3×1 splitter. The optical signals output by the 3×1 splitters 1˜128 are respectively input to the 1˜128 receiving units RX. Thus the Drop from any direction with any wavelength to any of the 128 receiving units can be achieved.
In summary, the present invention can be used to achieve the following functions:
1. Flexible wavelength scheduling function between different line directions;
2. wavelength configurable Add and Drop function;
3. wavelength loopback function: the optical signal transmitted from the direction 1 can be crossed through the configuration, but it still access to the direction;
4. the routing protection function of the wavelength; if the directions 1 and 2 can reach the same receiving end after passing through several nodes, when the direction 1 fails, the optical signal can be crossed to the direction 2 to be transmitted, thus to achieve the protection, and the routing means automatically searching for the protection path;
5. add multiple optical signals with same wavelength in the node;
6. drop the optical signals with the same wavelength in different directions;
7. the wavelength signals in any direction can be added or dropped at all Add and Drop ports.
Of course, the present invention might have a variety of other embodiments, and without departing from the spirit and essence of the present invention, those skilled in the field can make the corresponding modifications and variations according to the present invention, and all these modifications and variations should belong to the protection scope of the appended claims in the present invention.
For the method and system in the present invention, the designing method is simple, and the equipment can be easily implemented; the number of input and output ports of the optical crossbar switch can be flexibly selected; when there are a relatively large number of line directions, it has a significant cost advantage.
Number | Date | Country | Kind |
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200910181126.2 | Oct 2009 | CN | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CN2010/074508 | 6/25/2010 | WO | 00 | 4/10/2012 |