Abstract: A communication signal multiplexing apparatus includes first and second optical receivers, with the second optical receiver configured to receive an optical analog radio signal and to convert it into a corresponding electrical analog radio signal having a carrier frequency and the first optical receiver configured to receive an optical digital communication signal and to convert it into a corresponding electrical digital communication signal having a frequency spectrum. Further, a first electrical filter apparatus is configured to receive the electrical digital communication signal, and comprises a low-pass filter having a cut-off frequency lower than the carrier frequency of the electrical analog radio signal, and applies the low-pass filter to the electrical digital communication signal.

Abstract: An Optical Dispersion Compensator (ODC) is disclosed, the ODC being suitable for managing chromatic dispersion of an optical signal for transmission over an optical fiber. The ODC comprises a first ODC unit (202) arranged on a first optical bus (206), a second ODC unit (204) arranged on a second optical bus (208), parallel to the first optical bus (206), and a switching element (210) interconnecting the first and second optical buses (206, 208) between the first and second ODC units (202, 204). The first and second ODC units (202, 204) are operable to provide a delay to the optical signal that varies with frequency. The switching element (210) is configured, in a first state, to switch an optical signal received on one of the first or second optical buses (206, 208) to the other of the first or second optical buses (208, 206) and, in a second state, to maintain an optical signal received on one of the first or second optical buses (206, 208) on the optical bus on which it was received (206, 208).

Abstract: Methods in an optical receiver, for decoding a received M-level pulse-amplitude-modulated, PAM-M, optical signal. An example method comprises, for a first interval, decoding (510) the received PAM-M optical signal using a standard PAM-M decoder with M-1 thresholds, using first sampling times, to obtain a first set of decoded bits, and decoding (520) the received PAM-M optical signal using a duobinary decoder with 2M-2 thresholds, at second sampling times offset from the first sampling times, to obtain second set of decoded bits. The method further comprises calculating (530) first and second error metrics corresponding to the first and second sets of decoded bits, respectively, and selecting (540) the standard PAM-M decoder or the duobinary decoder for subsequent decoding of the received PAM-M optical signal, based on the first and second error metrics.

Abstract: An optical receiver (100) comprising: a polarisation controller (102) arranged to receive as its input a first modulated optical signal having a first polarisation and an unmodulated optical carrier signal polarisation aligned with the first modulated optical signal, the first modulated optical signal having negligible spectral power density within a predetermined bandwidth, BW, around an optical spectrum of the unmodulated optical carrier signal; optical filter apparatus (104) having a main polarisation mode; and coherent optical receiver apparatus (106), wherein the polarisation controller is arranged to apply polarisation rotations to the first modulated optical signal and the unmodulated optical carrier signal such that their polarisation is aligned to the main polarisation mode of the optical filter apparatus, the optical filter apparatus is arranged to receive and separate the unmodulated optical carrier signal from the first modulated optical signal, and the coherent optical receiver apparatus is arran

Abstract: A container cabinet has a box-like structure and a door connected to the box-like structure by an articulated quadrilateral. The box-like structure has a first side shoulder and a second side shoulder, an upper panel, a lower panel, and a front part. The articulated quadrilateral, supporting and guiding the door from a door closing position to a door maximum opening position, has a crank having a first crank end and a second crank end, and a rocker arm. The crank is hinged with the first crank end to the door and with the second crank end to the upper or lower panel to rotate about a crank vertical rotation axis. The rocker arm is connected, on one side, to the door and, on an opposite side, to the first side shoulder and has a movable side panel having a movable side panel front end and a movable side panel rear end, respectively hinging the movable side panel to the door and to the first side shoulder.

Abstract: Communication signal multiplexing apparatus (100) comprising: a first optical receiver (102) configured to receive an optical analog radio signal and to convert it into a corresponding electrical analog radio signal having a carrier frequency; a second optical receiver (104) configured to receive an optical digital communication signal and to convert it into a corresponding electrical digital communication signal having a frequency spectrum; first electrical filter apparatus (106) configured to receive the electrical digital communication signal, comprising a low-pass filter having a cut-off frequency lower than the carrier frequency of the electrical analog radio signal, and configured to apply the low-pass filter to the electrical digital communication signal; signal combining apparatus (108) configured to combine the low-pass filtered electrical digital communication signal with the electrical analog radio signal to form a combined electrical signal; and an optical transmitter (110) configured to generate

Abstract: A method for monitoring a passive optical network, the passive optical network comprising a plurality of network components, comprises receiving an alert message (200) from a fault detection system associated with the passive optical network, the alert message comprising an indication of one or more candidate locations for a detected fault in the passive optical network. The method further comprises accessing an inventory (202) of the plurality of network components, the inventory storing, for each of the plurality of network components, information comprising the network component location. The method further comprises identifying (204), based on the one or more candidate locations and the network component locations, one or more network components of the plurality of network components as candidates for the cause of the detected fault.

Abstract: An Optical Dispersion Compensator (ODC) is disclosed, the ODC being suitable for managing chromatic dispersion of an optical signal for transmission over an optical fiber. The ODC comprises a first ODC unit (202) arranged on a first optical bus (206), a second ODC unit (204) arranged on a second optical bus (208), parallel to the first optical bus (206), and a switching element (210) interconnecting the first and second optical buses (206, 208) between the first and second ODC units (202, 204). The first and second ODC units (202, 204) are operable to provide a delay to the optical signal that varies with frequency. The switching element (210) is configured, in a first state, to switch an optical signal received on one of the first or second optical buses (206, 208) to the other of the first or second optical buses (208, 206) and, in a second state, to maintain an optical signal received on one of the first or second optical buses (206, 208) on the optical bus on which it was received (206, 208).

Abstract: A data center network node (28) comprises one or more switch (18,19,22,23) configured to link an optical transceiver (16,17) to an optical connection comprising a multi-core optical fiber (30) having a plurality of cores (31). For each core (31), the one or more switch (18,19,22,23) is configurable between a first configuration in which an optical signal on a said core (31) of the multi-core optical fiber bypasses the optical transceiver and a second configuration in which the optical transceiver is optically linked to the said core (31) of the multi-core optical fiber (30).

Abstract: A radio over fibre system (5) comprises a base station (10, 20) with a first base station node (10) and a second base station node (20) connected by an optical communication link (30). At least one of the base station nodes (10, 20) comprises an optical transmitter (17, 23). A method of determining an operating parameter for the optical transmitter (17, 23) comprises receiving signal quality parameters for a plurality of user equipments (UE) served by the base station (10, 20). The method determines an operating parameter of the optical transmitter using the determined signal quality parameters of the plurality of user equipments (UE). The operating parameter of the optical transmitter can be a modulation parameter.

Abstract: A data center network node comprising at least one server connection for connecting to a server 6, a connection 7 for connecting the at least one server 6 to a first subnetwork. The first subnetwork is a conventional subnetwork which comprises at least one of a switch or a router. The node further comprises an optical receiver array 20 for connecting the node to an optical offload subnetwork, wherein the optical receiver array 20 comprises a plurality of optical receivers. The array is configured such that each receiver is connectable to an optical path within a multi-path optical connection. The node further comprises an optical transmitter array 23 for connecting the node to an optical offload subnetwork. The optical transmitter array comprises a plurality of optical transmitters. The array is configured such that each receiver is connectable to an optical path within a multi-path optical connection.

Abstract: A method for monitoring a passive optical network, the passive optical network comprising a plurality of network components, comprises receiving an alert message (200) from a fault detection system associated with the passive optical network, the alert message comprising an indication of one or more candidate locations for a detected fault in the passive optical network. The method further comprises accessing an inventory (202) of the plurality of network components, the inventory storing, for each of the plurality of network components, information comprising the network component location. The method further comprises identifying (204), based on the one or more candidate locations and the network component locations, one or more network components of the plurality of network components as candidates for the cause of the detected fault.

Abstract: A data center network node (28) comprises one or more switch (18,19,22,23) configured to link an optical transceiver (16,17) to an optical connection comprising a multi-core optical fiber (30) having a plurality of cores (31). For each core (31), the one or more switch (18,19,22,23) is configurable between a first configuration in which an optical signal on a said core (31) of the multi-core optical fiber bypasses the optical transceiver and a second configuration in which the optical transceiver is optically linked to the said core (31) of the multi-core optical fiber (30).

Abstract: A data center network node (13) comprising a first data connection (22) for connecting at least one server to a conventional subnetwork comprising at least one of a switch or a router, an optical transceiver (14) comprising a transmitter (16) and a receiver (17), a second data connection (23) for connecting the at least one server to the optical transceiver, a switching arrangement (21) for linking the optical transceiver (14) to an offload subnetwork (10), the switching arrangement configurable between a first configuration (24) in which the offload subnetwork bypasses the optical transceiver and a second configuration (28) in which the optical transceiver is optically linked to the offload subnetwork.

Abstract: A hybrid multiplexing apparatus is provided for multiplexing a digital communication signal from an electrical domain with one or more analog subcarrier communication signals from the electrical domain into a multiplexed optical signal for transmission over a common optical communication link. The apparatus comprises a laser module configured to modulate a laser source with the one or more analog subcarrier communication signals to be multiplexed, and output an intermediate optical modulated signal. An electro-optical modulator is coupled to receive the intermediate optical modulated signal and the digital communication signal to be multiplexed, and configured to modulate the intermediate optical modulated signal with the digital communication signal to form the multiplexed optical signal.

Abstract: An optical source comprises a first laser arranged to generate a first optical signal having a first state of polarization (SOP) and a first optical frequency; a second laser arranged to generate a second optical signal having a second SOP, substantially orthogonal to the first SOP, and having a second optical frequency, different from the first optical frequency by a preselected frequency difference; a polarisation beam coupler arranged to combine the first optical signal and the second optical signal into a composite optical signal comprising both the first optical signal and the second optical signal having said substantially orthogonal SOPs; and an output arranged to output the composite optical signal.

Abstract: A method in a node of a telecommunication network comprises receiving a digital communication signal from a first signal source, source, wherein the digital communication signal comprises a wherein the digital communication signal comprises a plurality of low amplitude windows, step 101, and receiving one or more analog subcarrier signals from a second signal source, step 103. The method further comprises multiplexing the one or more analog subcarrier signals into one or more of the plurality of low amplitude windows of the digital communication signal, step 105.

Abstract: A data center network node comprising at least one server connection for connecting to a server 6, a connection 7 for connecting the at least one server 6 to a first subnetwork. The first subnetwork is a conventional subnetwork which comprises at least one of a switch or a router. The node further comprises an optical receiver array 20 for connecting the node to an optical offload subnetwork, wherein the optical receiver array 20 comprises a plurality of optical receivers. The array is configured such that each receiver is connectable to an optical path within a multi-path optical connection. The node further comprises an optical transmitter array 23 for connecting the node to an optical offload subnetwork. The optical transmitter array comprises a plurality of optical transmitters. The array is configured such that each receiver is connectable to an optical path within a multi-path optical connection.

Abstract: A data center network node (13) comprising a first data connection (22) for connecting at least one server to a conventional subnetwork comprising at least one of a switch or a router, an optical transceiver (14) comprising a transmitter (16) and a receiver (17), a second data connection (23) for connecting the at least one server to the optical transceiver, a switching arrangement (21) for linking the optical transceiver (14) to an offload subnetwork (10), the switching arrangement configurable between a first configuration (24) in which the offload subnetwork bypasses the optical transceiver and a second configuration (28) in which the optical transceiver is optically linked to the offload subnetwork.

Abstract: A hybrid multiplexing apparatus is provided for multiplexing a digital communication signal from an electrical domain with one or more analog subcarrier communication signals from the electrical domain into a multiplexed optical signal for transmission over a common optical communication link. The apparatus comprises a laser module configured to modulate a laser source with the one or more analog subcarrier communication signals to be multiplexed, and output an intermediate optical modulated signal. An electro-optical modulator is coupled to receive the intermediate optical modulated signal and the digital communication signal to be multiplexed, and configured to modulate the intermediate optical modulated signal with the digital communication signal to form the multiplexed optical signal.