COMMUNICATION SYSTEM AND METHOD FOR DIRECTLY TRANSMITTING SIGNALS BETWEEN NODES OF A COMMUNICATION SYSTEM

• US 20120177373A1
• Filed: 01/09/2012
• Published: 07/12/2012
• Est. Priority Date: 01/10/2011
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Biermann, Thorsten, Choi, Changsoon, Wei, Qing
• Granted Patent: US 8,837,943 B2
• Time in Patent Office: Days
• US Class Current: 398/72
• CPC Class Codes: H04J 14/0235 for upstream transmission
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/025 using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU

Abstract

A communication system has a plurality of nodes adapted to provide for a communication with one or more devices, a central node, a passive optical network having a multiplexer/demultiplexer device adapted to demultiplex a first optical signal from the central node to the plurality of nodes, and to multiplex second optical signals from one or more of the nodes, each node having allocated a wavelength for generating its optical signal, wherein for directly transmitting signals from one node to at least one of the other nodes, the one node is adapted to generate an optical signal at the wavelength allocated to the at least one of the other nodes, the optical signal including the signal to be transmitted, and wherein the multiplexer/demultiplexer device of the passive optical network is adapted to combine the optical signal from the one node with the first optical signal.

Claims

1. A communication system, comprising:

a plurality of nodes adapted to provide for a communication with one or more devices;

a central node;

a passive optical network comprising a multiplexer/demultiplexer device adapted to demultiplex a first optical signal from the central node to the plurality of nodes, and to multiplex second optical signals from one or more of the nodes, each node comprising allocated a wavelength for generating its optical signal;

wherein for directly transmitting signals from one node to at least one of the other nodes, the one node is adapted to generate an optical signal at the wavelength allocated to the at least one of the other nodes, the optical signal comprising the signal to be transmitted; and

wherein the multiplexer/demultiplexer device of the passive optical network is adapted to combine the optical signal from the one node with the first optical signal.

2. The communication system of claim 1, wherein for a point-to-point communication from the one node to one of the other nodes, the one node is adapted to select the wavelength allocated to the other node and to generate the optical signal at the selected wavelength.

3. The communication system of claim 2, wherein the one node comprises a narrow spectrum optical source, and wherein the one node is adapted to set the narrow spectrum optical source to the selected wavelength, to modulate the signal to be transmitted to the output signal of the narrow spectrum optical source for generating the optical signal, and to transmit the optical signal to the multiplexer/demultiplexer device.

4. The communication system of claim 1, wherein for a broadcast communication from the one node to a plurality of the other nodes, the one node is adapted to generate the optical signal at the wavelengths allocated to the other nodes.

5. The communication system of claim 4, wherein the one node comprises a broad spectrum optical source comprising the wavelengths allocated to the plurality of nodes, and wherein the one node is adapted to modulate the signal to be broadcast to the output signal of the broad spectrum optical source to generate the optical signal, and to transmit the optical signal to the multiplexer/demultiplexer device.

6. The communication system of claim 1, wherein a node comprises:

an optical detector adapted to detect an optical signal at the wavelength allocated to the node, and

an optical source adapted to provide a signal at the wavelength allocated to the node on the basis of which the second signal is generated which is to be transmitted from the node to the central node.

7. The communication system of claim 1, wherein the multiplexer/demultiplexer device of the passive optical network comprises:

a first input/output port adapted to be coupled to the central node;

a plurality of second input/output ports adapted to be coupled to the respective nodes; and

a passive optical coupler arranged between the plurality of second input/output ports and the first input/output port, the passive optical coupler being adapted to couple one or more of the second signals received at the plurality of second input/output ports to the first input/output port.

8. The communication system of claim 1, wherein

the communication system is a wireless communication system,

the plurality of nodes are adapted to provide a wireless communication with one or more wireless devices,

the central node is a central switching node,

the passive optical network forms the backhaul link between the central switching node and the nodes, and

the signal to be transmitted directly between the nodes comprises X2 data.

9. A node adapted to be coupled via a passive optical network to a central node and a plurality of further nodes of a communication system,

wherein the node comprises allocated a wavelength for optical signal transmission that is different from wavelengths allocated to the further nodes,

wherein the node comprises an optical source adapted to generate an output signal at at least one of the wavelengths allocated to the further nodes, and

wherein for a direct transmission of a signal from the node to at least one of the further nodes, the node is adapted to generate an optical signal at the needed one or more wavelengths, the optical signal comprising the signal to be transmitted.

10. The node of claim 9, wherein the optical source comprises:

a narrow spectrum optical source adapted to be tuned to one of the wavelengths allocated to the further nodes and/or a broad spectrum optical source comprising the wavelengths allocated to the further nodes,

wherein for a point-to-point communication from the node to one of the further nodes, the node is adapted to tune the narrow spectrum optical source to the wavelength allocated to the one further node, and to generate the optical signal at the wavelength, and

wherein for a broadcast communication from the node to the further nodes, the node is adapted to generate the optical signal on the basis of the output signal of the broad spectrum optical source.

11. The node of claim 10, wherein the narrow spectrum optical source comprises a tunable laser, and wherein the broad spectrum optical source comprises a light emitting diode.

12. An optical multiplexer/demultiplexer device for a communication system, the communication system comprising a plurality of nodes and a central node coupled via a passive optical network, the optical multiplexer/demultiplexer device comprising:

a first input/output port adapted to be coupled to the central node;

a plurality of second input/output ports adapted to be coupled to the respective nodes, wherein the multiplexer/demultiplexer device is adapted to demultiplex a first optical signal from the central node to the plurality of nodes, and to multiplex second optical signals from one or more of the nodes; and

a passive optical coupler arranged between the plurality of second input/output ports and the first input/output port, the passive optical coupler being adapted to couple one or more of the second signals received at the plurality of second input/output ports to the first input/output port.

13. The optical multiplexer/demultiplexer device of claim 12, comprising an arrayed waveguide grating.

14. A method for directly transmitting signals between nodes of a communication system, the communication system comprising the plurality of nodes providing for communication with one or more devices, a central node, and a passive optical network comprising a multiplexer/demultiplexer device for demultiplexing a first optical signal from the central node to the plurality of nodes, and for multiplexing second optical signals from one or more of the nodes, each node comprising allocated a wavelength for generating its optical signal, the method comprising:

for directly transmitting signals from one node to at least one of the other nodes, generating at the one node an optical signal at the wavelength allocated to the at least one of the other nodes, the optical signal comprising the signal to be transmitted; and

combining the optical signal from the one node with the first optical signal at the multiplexer/demultiplexer device.

15. A computer program product comprising instructions stored by a machine readable carrier for carrying out the method for directly transmitting signals between nodes of a communication system, the communication system comprising the plurality of nodes providing for communication with one or more devices, a central node, and a passive optical network comprising a multiplexer/demultiplexer device for demultiplexing a first optical signal from the central node to the plurality of nodes, and for multiplexing second optical signals from one or more of the nodes, each node comprising allocated a wavelength for generating its optical signal, the method comprising:

for directly transmitting signals from one node to at least one of the other nodes, generating at the one node an optical signal at the wavelength allocated to the at least one of the other nodes, the optical signal comprising the signal to be transmitted; and

combining the optical signal from the one node with the first optical signal at the multiplexer/demultiplexer device, when executing the instructions on a computer.