Abstract: A beamforming device for a phased array antenna, comprising: a laser light source (2) arranged to provide an optical spectrum comprising a plurality of spaced wavelengths, and a distribution unit (4) configured to distribute one or more of the plurality of spaced wavelengths onto a plurality of optical paths (6). A wavelength selection device (8) configured to receive the plurality of spaced wavelengths on each of the plurality of optical paths. One or more phase shift unit (12) connected to a said wavelength selection device, wherein the phase shift unit is configured to introduce a phase shift to a received wavelength. The wavelength selection device on each optical path is configured to selectively transmit a wavelength to the phase shift unit. The wavelength selection device is configured to receive the said phase shifted wavelength from the phase shift unit (12).

Abstract: A plurality of sub-cells are defined within a cell area of a radio communication network by the intersection of a radio paths of a plurality of directional radio antennas. The plurality of directional radio antennas are arranged to broadcast radio signals simultaneously, and to receive radio signals simultaneously. This disclosure relates to determining of signal values transmitted by or received from the plurality of directional radio antennas in a radio communication network.

Abstract: The present invention provides an optical source comprising a laser, a first optical power splitter, phase changing equipment, polarisation state setting equipment, a polarisation beam coupler and an output. The laser is configured to generate an optical signal. The first optical power splitter is configured to split the optical signal into a first optical signal and a second optical signal. The phase changing equipment is configured to change the phase of at least one of the first optical signal and the second optical signal such that the first optical signal has a first phase and the second optical signal has a second phase different from the first phase by a preselected phase difference.

Abstract: Transmitting and receiving apparatuses, transmitting and receiving methods, and a transceiver for a phased array antenna are provided. The transmitting apparatus may comprise a laser light source configured to provide an optical beam comprising one or more spectral components. The transmitting apparatus may comprise a modulator configured to modulate the optical beam with a signal to be transmitted. The transmitting apparatus may comprise one or more group delay controlling units configured to add one or more controllable time delays to the one or more spectral components. Further, the transmitting apparatus may comprise a plurality of waveguides each having a chromatic dispersion configured to guide the optical beam, wherein the laser light source is tunable to control time delays added by the plurality of waveguides.

Abstract: An opto-electronic oscillator (10) comprising: an optical source (12) to generate an optical carrier signal having a carrier wavelength; an optical phase modulator (14) to apply a sinusoidal phase modulation to the optical carrier signal to generate two first order sidebands having a ? phase difference between them; an optical phase shifter (16) comprising an optical resonator configured to apply a substantially ? phase-shift to one of the first order sidebands at a preselected wavelength within an optical spectrum of said first order sideband; and a photodetector (18) configured to perform optical heterodyne detection of the optical carrier signal with both: said one of the first order sidebands substantially it phase shifted by the optical resonator; and the other of the first order sidebands, to generate an electrical carrier signal (20), and wherein a first part of the electrical carrier signal (20a) is delivered to an electrical output (22) and a second part of the electrical carrier signal (20b) is deli

Abstract: The invention provides a free space optical (FSO) communications terminal for a first telecommunications card or a backplane. The FSO terminal comprises a plurality of transmission interfaces. The FSO terminal further comprises a light signal generating unit adapted to generate a plurality of light signals. Each of the plurality of light signals carries the same information as the other one or more of the plurality of light signals and is arranged for transmission through a respective one of the plurality of transmission interfaces. Each of the plurality of light signals is at a different orthogonal mode from the other one or more of the plurality of light signals. The invention further provides a free space optical (FSO) communications terminal for a second telecommunications card or a backplane. The FSO terminal comprises a plurality of receive interfaces. Each of the plurality of receive interfaces adapted to receive a light signal carrying information.

Abstract: Anode for burst switching of traffic flows in an optical network switches bursts of traffic flows in different time slots. Time slots are allocated (96) so that a time gap between successive allocated time slots is selected according to a jitter specification of the traffic flow. A map of the allocations controls a burst switch to pass the bursts in their allocated time slots (86). By making the time gap between allocated time slots for successive bursts selectable, the jitter can be controlled more precisely, or the proportion of time slots filled can be increased resulting in better utilization of available bandwidth. The allocation can be made hop by hop. The map can be generated in a distributed and duplicated manner at each node. The allocation can be updated to adapt to changes bandwidth demands.

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 (10) of routing communications traffic packets across a communications network comprising a plurality of nodes and a plurality of links interconnecting respective pairs of the nodes, the method comprising steps: a) for links of the network, obtaining a respective plurality of measurements of a parameter indicative of a quality of forwarding communications traffic packets across the link (12); b) for each said link, calculating from the respective plurality of measurements of the parameter an index indicative of a percentage of the respective plurality of measurements of the parameter for which the parameter satisfies a preselected threshold value of the parameter (14); and c) selecting a path for communications traffic packets across the communications network by selecting links for the path based on the respective index of each said link (16).

Abstract: A beamforming device for a phased array antenna, comprising: a laser light source (2) arranged to provide an optical spectrum comprising a plurality of spaced wavelengths, and a distribution unit (4) configured to distribute one or more of the plurality of spaced wavelengths onto a plurality of optical paths (6). A wavelength selection device (8) configured to receive the plurality of spaced wavelengths on each of the plurality of optical paths. One or more phase shift unit (12) connected to a said wavelength selection device, wherein the phase shift unit is configured to introduce a phase shift to a received wavelength. The wavelength selection device on each optical path is configured to selectively transmit a wavelength to the phase shift unit. The wavelength selection device is configured to receive the said phase shifted wavelength from the phase shift unit (12).

Abstract: An optical source (10) comprising: a first laser (12) arranged to generate a first optical signal (14) having a first state of polarization and a first optical frequency; a second laser (16) arranged to generate a second optical signal (18, 48, 78) having a second state of polarization, substantially orthogonal to the first state of polarization, and having a second optical frequency, different to the first optical frequency by a preselected frequency difference, ??; a polarization beam coupler (20) 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 states of polarization; and an output (22) arranged to output the composite optical signal (24).

Abstract: An optical source (10) comprising: a first laser (12) arranged to generate a first optical signal (14) having a first state of polarization and a first optical frequency; a second laser (16) arranged to generate a second optical signal (18, 48, 78) having a second state of polarization, substantially orthogonal to the first state of polarization, and having a second optical frequency, different to the first optical frequency by a preselected frequency difference, ??; a polarization beam coupler (20) 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 states of polarization; and an output (22) arranged to output the composite optical signal (24).

Abstract: An optical carrier selector system is provided for selecting a wanted carrier signal from a multi-carrier signal comprising a plurality of carrier signals. The optical carrier selector system comprises a series of optical filter devices. Each optical filter device of the series comprises an input port for receiving a signal comprising two or more carrier signals, each optical filter device being configured to filter out an unwanted carrier signal. Each optical filter device also comprises an output port for outputting at least the wanted carrier signal and any remaining signals that have not been filtered out by that particular optical filter device, and a drop port for outputting the unwanted carrier signal that is being filtered out by the respective optical filter device.

Abstract: A periodic phase modulation, having a period shorter than a symbol period, is applied as a source modulation, in addition to a symbol modulation, to signals transmitted between a transmitter and a receiver in a communication network. Symbol value elements can be sent from multiple transmitters (203, 303, 603, 703) to a receiver (607, 207) in the same symbol period can be processed on the basis of the source modulation without destructive interference. In some embodiments, the symbol value elements sent by different transmitters can be combined in the receiver. In some embodiments, symbol value elements sent by different transmitters can be distinguished in the receiver.

Abstract: A feed signal generator (10) for a phased array antenna, comprising: an input (12) to receive an optical spectrum having first and second phase-locked spectral components, respectively having first and second optical frequencies; wavelength selective separator apparatus (14) to separate the optical spectrum into a first optical signal being the first spectral component and a second optical signal being the second spectral component; an optical time delay element (16) to apply a time delay to the first optical signal to form a delayed optical signal; a heterodyning device (20) to heterodyne the delayed optical signal and the second optical signal to generate a feed signal (22) having a power proportional to a product of the amplitudes of the second and delayed optical signals and a phase proportional to the time delay; and optical amplitude control apparatus (18) to set an amplitude of the delayed optical signal such that the product of said amplitudes causes the power of the feed signal to have a preselected

Abstract: A receiver (1) for a phased array antenna comprises a laser light source (2) arranged to provide an optical spectrum comprising a first spectral component having a first wavelength and a second spectral component having a second wavelength. The first wavelength is spaced from the second wavelength. A wavelength separator (4) is configured to separate the first spectral component from the second spectral component, such that the first spectral component is directed onto a first path (A) and the second spectral component is directed onto a second path (B). A first delay unit (16) is configured to add a controllable time delay to the first spectral component on the first path. A second delay unit (42) is configured to add the time delay to the second spectral component on the second path. A modulator (14) is configured to modulate the first spectral component on the first path with a received RF signal from the phased array antenna.

Abstract: A plurality of sub-cells are defined within a cell area of a radio communication network by the intersection of a radio paths of a plurality of directional radio antennas. The plurality of directional radio antennas are arranged to broadcast radio signals simultaneously, and to receive radio signals simultaneously. This disclosure relates to determining of signal values transmitted by or received from the plurality of directional radio antennas in a radio communication network.

Abstract: There is provided an optical source. The optical source comprises a reflective optical amplifier configured to generate an optical signal, the optical signal comprising an amplified spontaneous light emission having a plurality of light modes each having a respective wavelength. The optical source further comprises a reflective mirror, spaced from the reflective optical amplifier, and arranged to receive the optical signal and to rotate a polarization of each light mode in the received optical signal, to form a further optical signal. The optical source further comprises an optical power splitter arranged to receive the further optical signal and to split the further optical signal into a first optical signal which is directed to the reflective optical amplifier for amplification thereby, and a second optical signal. The optical source further comprises an output arranged to output the second optical signal.

Abstract: An optical carrier selector system is provided for selecting a wanted carrier signal from a multi-carrier signal comprising a plurality of carrier signals. The optical carrier selector system comprises a series of optical filter devices. Each optical filter device of the series comprises an input port for receiving a signal comprising two or more carrier signals, each optical filter device being configured to filter out an unwanted carrier signal. Each optical filter device also comprises an output port for outputting at least the wanted carrier signal and any remaining signals that have not been filtered out by that particular optical filter device, and a drop port for outputting the unwanted carrier signal that is being filtered out by the respective optical filter device.

Abstract: The present invention provides an optical source comprising a laser, a first optical power splitter, phase changing equipment, polarisation state setting equipment, a polarisation beam coupler and an output. The laser is configured to generate an optical signal. The first optical power splitter is configured to split the optical signal into a first optical signal and a second optical signal. The phase changing equipment is configured to change the phase of at least one of the first optical signal and the second optical signal such that the first optical signal has a first phase and the second optical signal has a second phase different from the first phase by a preselected phase difference.