Optical node

• US 10,419,148 B2
• Filed: 09/24/2014
• Issued: 09/17/2019
• Est. Priority Date: 09/24/2014
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Bottari, Giulio, Cavaliere, Fabio, Testa, Francesco
• Primary Examiner(s): Cors, Nathan M
• Application Number:
  US15/511,265
• Publication Number:
  US 20180234200A1
• Time in Patent Office: 1,819 Days
• CPC Class Codes: H04J 14/0204 Broadcast and select arrangements, e.g. with an optical splitter at the input before adding or dropping
• CPC Class Codes: H04J 14/0205 Select and combine arrangements, e.g. with an optical combiner at the output after adding or dropping
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0016 using wavelength multiplexing or demultiplexing

Abstract

An optical node (100) is disclosed. The optical node (100) comprises first and second line ports (104, 106) for Wavelength Division Multiplexing (WDM) signals and first and second pluralities of local add/drop ports (108, 110) for optical signals. The optical node further comprises a wavelength selective switch (112), coupled between the first and second line ports (104, 106) and configured to drop optical signals from a WDM signal traversing the optical node between the first and second line ports (104, 106), and a node optical combiner (114) coupled between the first and second line ports (104, 106) and configured to add optical signals to a WDM signal traversing the optical node between the first and second line ports (104, 106). The optical node also comprises first and second switching units (116, 118), each switching unit coupled to the wavelength selective switch (112), the node optical combiner (114), a respective one of the first and second pluralities of local add/drop ports (108, 110) and the other of the first and second switching units (116, 118). Each of the first and second switching units (116, 118) is configured to distribute dropped optical signals from the wavelength selective switch (112) to its coupled plurality of local add/drop ports and to provide optical signals from its coupled plurality of local add/drop ports to the node optical combiner (114). Each of the first and second switching units (116, 118) is also configured to distribute optical signals from its coupled plurality of local add/drop ports to the other of the first and second switching units (116, 118) and to distribute optical signals from the other of the first and second switching units to its coupled plurality of local add/drop ports.

Claims

1. An optical node, comprising:

first and second line ports for Wavelength Division Multiplexing (WDM) signals;

first and second pluralities of local add/drop ports for optical signals;

a wavelength selective switch coupled between the first and second line ports and configured to drop optical signals from a WDM signal traversing the optical node between the first and second line ports;

a node optical combiner coupled between the first and second line ports and configured to add optical signals to a WDM signal traversing the optical node between the first and second line ports; and

first and second switching units, each switching unit of the first and second switching units coupled to the wavelength selective switch, the node optical combiner, a respective one of the first and second pluralities of local add/drop ports, and the other of the first and second switching units,

wherein each of the first and second switching units is configured to distribute the dropped optical signals from the wavelength selective switch to its coupled plurality of local add/drop ports and to provide optical signals from its coupled plurality of local add/drop ports to the node optical combiner,

wherein each of the first and second switching units is also configured to distribute optical signals from its coupled plurality of local add/drop ports to the other of the first and second switching units and to distribute optical signals from the other of the first and second switching units to its coupled plurality of local add/drop ports,

wherein each of the first and second switching units comprises a receive switching device and a transmit switching device, and wherein the receive switching device of each switching unit comprises;

a local connectivity WDM signal input coupled to an output of the transmit switching device of the other switching unit;

a remote connectivity WDM signal input coupled to an output of the wavelength selective switch;

a plurality of optical signal outputs, each of the plurality of optical signal outputs coupled to a drop output of a respective one of the first and second pluralities of local add/drop ports to which the switching unit of the receive switching device is coupled;

a local connectivity splitter, arranged to receive a WDM signal from the local connectivity WDM signal input of the receive switching device;

a remote connectivity splitter, arranged to receive a WDM signal from the remote connectivity WDM signal input of the receive switching device;

a plurality of optical switches; and

a plurality of optical tunable filters, each optical tunable filter coupled between an output of a respective optical switch and a respective one of the plurality of optical signal outputs of the receive switching device,

wherein each of the local connectivity splitter and the remote connectivity splitter is configured to duplicate its received WDM signal and to send a duplicate of the received WDM signal to an input of each of the plurality of optical switches,

wherein each of the plurality of optical switches is configured to select which of the received duplicate WDM signals to transmit, and

wherein each of the tunable optical filters is configured to extract a wavelength from the transmitted WDM signal corresponding to the optical signal output of the receive switching device to which it is coupled.

2. The optical node as claimed in claim 1, wherein the first plurality of local add/drop ports is equal in number to the second plurality of local add/drop ports.

3. The optical node as claimed in claim 1, wherein each local add/drop port in the first and second pluralities of local add/drop ports is operable for connection to a pair of unidirectional optical fibers, each fiber hosting a single wavelength.

4. The optical node as claimed in claim 1, wherein the receive and transmit switching devices of each switching unit comprise split and select switches.

5. The optical node as claimed in claim 1, wherein each of the plurality of optical switches is configured to select which of the received duplicate WDM signals to transmit on the basis of a received control signal.

6. The optical node as claimed in claim 1, wherein each of the tunable optical filters is configured to extract the wavelength from the transmitted WDM signal corresponding to the optical signal output of the receive switching device to which it is coupled on the basis of a received control signal.

7. The optical node as claimed in claim 1, wherein the transmit switching device of each switching unit comprises:

a plurality of optical signal inputs, each optical signal input coupled to an add input of a respective one of the first and second pluralities of local add/drop ports to which the switching unit of the transmit switching device is coupled;

a local connectivity WDM signal output coupled to an input of the receive switching device of the other switching unit; and

a remote connectivity WDM signal output coupled to an input of the node optical combiner.

8. The optical node as claimed in claim 7, wherein the transmit switching device of each switching unit further comprises:

a local connectivity optical combiner, arranged to deliver a WDM signal to the local connectivity WDM signal output of the transmit switching device;

a remote connectivity optical combiner, arranged to deliver a WDM signal to the remote connectivity WDM signal output of the transmit switching device; and

a plurality of optical switches, each optical switch arranged to receive an optical signal from a respective one of the plurality of optical signal inputs of the transmit switching device,

wherein each of the plurality of optical switches is configured to transmit the optical signal received from its respective optical signal input to at least one of the local connectivity or remote connectivity optical combiners,

wherein the local connectivity optical combiner is configured to multiplex optical signals received from the plurality of optical switches into a WDM signal and to deliver the WDM signal to the local connectivity WDM signal output of the transmit switching device, and

wherein the remote connectivity optical combiner is configured to multiplex optical signals received from the plurality of optical switches into a WDM signal and to deliver the WDM signal to the remote connectivity WDM signal output of the transmit switching device.

9. The optical node as claimed in claim 8, wherein each of the plurality of optical switches is configured to select an optical combiner to transmit its received optical signal on the basis of a received control signal.

10. The optical node as claimed in claim 7, wherein the transmit switching device of at least one of the first or second switching units further comprises an internal switching unit output, coupled to an internal switching unit input of the receive switching device of the at least one of the first or second switching units.

11. The optical node as claimed in claim 1, further comprising:

a local connectivity amplification stage coupled between the first and second switching units; and

a remote connectivity amplification stage coupled between the first and second line ports.

12. The optical node as claimed in claim 11,

wherein the local connectivity amplification stage comprises:

a first local connectivity amplifier arranged to amplify a WDM signal from the local connectivity WDM signal output of the transmit switching device of the first switching unit; and

a second local connectivity amplifier arranged to amplify a WDM signal from the local connectivity WDM signal output of the transmit switching device of the second switching unit.

13. The optical node as claimed in claim 11, wherein the remote connectivity amplification stage comprises:

a first remote connectivity amplifier arranged to amplify a WDM signal for input to the wavelength selective switch; and

a second remote connectivity amplifier arranged to amplify a WDM signal from the node optical combiner.

14. A network sub-segment comprising:

the optical node as claimed in claim 1;

a plurality of Radio Equipment (RE) clusters, each RE cluster connected to a local add/drop port of the first plurality of local add/drop ports of the optical node; and

a plurality of Radio Equipment Controllers (RECs), the plurality of RECs connected to the second plurality of local add/drop ports of the optical node.

15. The network sub-segment as claimed in claim 14, wherein each RE cluster is connected to its respective local add/drop port on the optical node by a pair of unidirectional optical fibers.

16. The network sub-segment as claimed in claim 14, wherein each REC is connected to a number of local add/drop ports in the second plurality of local add/drop ports that corresponds to the number of RE clusters divided by the number of RECs.

17. The network sub-segment as claimed in claim 14, wherein each local add/drop port of the second plurality of local add/drop ports on the optical node is connected to an REC by a pair of unidirectional optical fibers.

18. A network segment, comprising:

a plurality of network sub-segments as claimed in claim 14; and

an optical infrastructure,

wherein the optical infrastructure is coupled to the first and second line ports of the optical nodes of the plurality of network sub-segments.

19. The network segment as claimed in claim 18, wherein the optical infrastructure comprises a pair of unidirectional optical fiber rings, each network sub-segment being mounted on each ring via a line input and a line output at each of the first and second line ports on its optical node.

20. The network segment as claimed in claim 18, wherein the optical node of each network sub-segment further comprises third and fourth line ports for WDM signals, and

wherein the optical infrastructure comprises an optical fiber mesh, each network sub-segment being connected to the optical fiber mesh via a line input and a line output at each of the first, second, third and fourth line ports on its optical node.

21. The network segment as claimed in claim 18, wherein the network segment comprises a fronthaul network segment for a Radio Access Network (RAN) of a cellular communications network.