Abstract: Embodiments described herein relate to methods and apparatus for carrying and using fronthaul network tracing information. In an example a method in a first RAN node includes recovering fronthaul network tracing information from a predetermined field of the frames in response to receiving frames of a predetermined type. The fronthaul network tracing information includes node identifier information for at least one other node of the fronthaul network through which the frame has traversed. The fronthaul network tracing information is associated with fronthaul routes of frames from other nodes through the fronthaul network to the first RAN node.

Abstract: An optical filter for an optical network is disclosed, the optical filter adaptively adds or removes a target wavelength in a predetermined filter range, the optical filter comprising: a first resonator having a first resonant wavelength outside a first sub-range of the predetermined filter range when a first resonance control variable of the first resonator is set at a first value, and a second resonant wavelength inside the first sub-range of the predetermined filter range when the first resonance control variable of the first resonator is set at a second value; and a second resonator having a third resonant wavelength outside a second sub-range of the predetermined filter range when a second resonance control variable of the second resonator is set at a third value, and a fourth resonant wavelength inside the second sub-range of the predetermined filter range when the second resonance control variable of the second resonator is set at a fourth value.

Abstract: Optical attenuators comprising electrochromic devices for telecommunications networks are provided. The optical attenuators are configured to reflect or refract an input optical signal using an electrochromic device, wherein the electrochromic device is configured to provide adjustable optical reflection or refraction levels.

Abstract: Methods and apparatuses for mobile communication systems are disclosed. According to an embodiment, there is provided a method in a mobile communication system having a radio access network, RAN, the radio access network having a first RAN node and a second RAN node connected by a transport network, the transport network having a first transport node and a second transport node, wherein the first RAN node is connected to the first transport node and the second RAN node is connected to the second transport node. The method includes, by the first transport node: determining the status of a transport network connection between the first transport node and the second transport node, generating a message indicating the status of the transport network connection, and initiating transmission of the message to the first RAN node.

Abstract: Device and method for processing an optical signal. The device includes a photonic device arranged between a first input/output and second input/output and optically communicating with the inputs/outputs by a signal path for transmission of an optical signal in a first or second direction between the first input/output and second input/output. The device includes an optical gain element for amplifying the optical signal. The device includes a path switching circuit including a first signal amplification path connectable between the first input/output and the photonic device for optically coupling the signal path to and from the optical gain element, and a second signal amplification path connectable between the photonic device and the second input/output for optically coupling the signal path to and from the optical gain element. The path switching circuit selectively connects the first or second signal amplification path into the signal path.

Abstract: A method (200) of controlling compensation of chromatic dispersion in an optical transport network. The method comprises determining (202) whether a residual dispersion, RD, of a first path (3) within the network is within a defined RD range and if the RD of the first path is outside the defined RD range the method comprises identifying (204) a first tuneable dispersion compensation module, TDCM, crossed by the first path (3), configured to apply a respective value of dispersion compensation.

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 method in a first level aggregation node of a transport network is disclosed. The transport network comprises the first level aggregation node, a second level aggregation node and a Passive Optical Network. T the method comprises receiving, from the second level aggregation node, a plurality of wavelength division multiplexing (WDM) channels having wavelengths in a first spectrum section and generating at least one passive optical channel having a wavelength in a second spectrum section, different to the first spectrum section. The method further comprises combining at least some of the WDM channels received from the second level aggregation node with the at least one passive optical channel, and forwarding the combined WDM channels and passive optical channel to a termination node in the Passive Optical Network. Also disclosed are a method in a termination node of a transport network, a first level aggregation node, a termination node and a computer program.

Abstract: There is provided a method comprising: detecting (310) a subset of protocol data units in an original stream of protocol data units to be transmitted over the network, wherein the original stream is associated with a first source port; generating (320) an updated transmitting-side stream of protocol data units based on the original stream, wherein the updated transmitting-side stream excludes the detected subset; merging (330) the subset of protocol data units with a subset of protocol data units associated with a second source port to form a merged stream; transmitting (340) the merged stream, as a first stream, over a first link of the network; transmitting (350) the updated transmitting-side stream associated with the first source port, as a second stream, over a second link; and transmitting (360) an updated transmitting-side stream associated with the second source port, as a third stream, over a third link.

Abstract: A method (100) of encoding communications traffic bits onto an optical carrier signal in a pulse amplitude modulation, PAM, format. The method comprises: receiving (102) bits to be transmitted; receiving (104) an optical carrier signal comprising optical pulses having an amplitude and respective phases; performing (106) PAM of the optical pulses to encode at least one respective bit in one of a pre-set plurality of amplitudes of a said optical pulse; and performing (108) phase modulation of the optical pulses to encode at least one further respective bit in a phase difference between a said optical pulse and a consecutive optical pulse.

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 method (200) of controlling compensation of chromatic dispersion in an optical transport network. The method comprises determining (202) whether a residual dispersion, RD, of a first path (3) within the network is within a defined RD range and if the RD of the first path is outside the defined RD range the method comprises identifying (204) a first tuneable dispersion compensation module, TDCM, crossed by the first path (3), configured to apply a respective value of dispersion compensation.

Abstract: Quantum bit decoding apparatus, configured to receive a photon having a qubit encoded in a property of the photon has a demodulation apparatus. The demodulation apparatus includes an optical modulator to randomly apply one of a plurality of modulation values for decoding the qubit to the property of the photon and an optical router to route the photon according to the qubit. The decoding apparatus has an optical delay apparatus having an optical combiner, a first optical path, from the optical router to the optical combiner and a second optical path, from the optical router to the optical combiner. The second path has a different optical path length from the first path. The decoding apparatus has a detection apparatus to detect a photon and to determine whether a detected photon is delayed relative to a reference time and to determine the qubit according to the determined delay.

Abstract: Methods and apparatus are provided for transmitting synchronization data over a FlexE communications link. In an example aspect, a method of transmitting synchronization data over a FlexE communications link includes, in response to a synchronization event, selecting a next slot of the FlexE communications link that is unallocated or is allocated to a FlexE client, and transmitting synchronization data associated with the synchronization event in the selected slot.

Abstract: A path computation engine, PCE, (100) for an optical communications network comprising a plurality of nodes and a plurality of links.

Abstract: A method for scheduling resources for a Wavelength Division Multiplexed, WDM, Passive Optical Network, PON. The WDM PON comprises a central hub (201) and a plurality of remote Optical Network Terminals, ONTs, (220) handling different types of communications traffic. The method (450) comprises receiving (452) a notification message from the plurality of remote Optical Network Terminals, ONTs, indicating a loading status of the ONT, and allocating (454) one or more slots to a plurality of the ONTs based on the received notification messages from the ONTs, wherein the plurality of ONTs (220) handle different types of communications traffic. The slots (301) are allocated based on the received notification messages as a time slot which is time division multiplexed with further time slots, and the slots are further allocated based on the received notification messages as an optical wavelength of a plurality of optical wavelengths of the WDM PON.

Abstract: A method of controlling transmission of an upstream packet traffic from a plurality of Optical Network Units to an Optical Line Terminal in a Passive Optical Network based fronthaul network. The Optical Network Units transmit packets in a time division multiplexed access scheme to the Optical Line Terminal and the method comprises obtaining mobile upstream scheduling information, scheduling the packet traffic from the plurality of Optical Network Units based on delay constraints of the PON-based front haul network and the obtained mobile upstream scheduling information. The method also comprises transmitting the scheduling of the packet traffic to the plurality of ONUs.

Abstract: A receiver module (100) is disclosed for receiving an optical input signal and generating an electrical output signal from the optical input signal. The receiver module comprises an input (110) for receiving an optical input signal and a polarising beam splitter (120) for splitting one of the optical input signal and a local recovery optical signal. The receiver module also comprises a multiport optical coupler (130) for coupling the outputs of the polarisation beam splitter and the other of the optical input signal and local recovery optical signal and outputting a plurality of outputs. The receiver module further comprises a first photodetector unit (140) for individually photodetecting the outputs of the multiport optical coupler and an optical modulation unit (150) for using each of the photodetected outputs to modulate a respective local conversion optical signal, where each local conversion optical signal has a different frequency from the other local conversion optical signals.

Abstract: An optical link for a communication network, the optical link having an optical fibre link, a downstream transmitter, a downstream receiver, an upstream transmitter and an upstream receiver. The upstream and downstream transmitters are configured to transmit a respective pilot tone on a respective optical carrier and are configured to tune a frequency of the pilot tone within a preselected frequency range. The upstream and downstream receivers are configured respectively to determine an upstream notch frequency, fnotch-US, and a downstream notch frequency, fnotch-DS, of respective detected photocurrents from at least one respective pilot tone frequency at which the respective detected photocurrent is equal to or lower than a photocurrent threshold. The optical link also includes processing circuitry configured to receive the upstream and downstream notch frequencies and configured to estimate a propagation delay difference of the optical link depending on the upstream and downstream notch frequencies.

Abstract: Methods and apparatus are provided for processing communications. In one aspect, a method comprises receiving first data from a first device and receiving second data from a second device, wherein the first data has a longer latency constraint than the second data. The method also comprises sending the first data over a network link to a processing node for processing the first data.