British Telecommunications Public Limited Company

Nextg Networks, Inc.

British Telecommunications Corporation

David Wake

David Graham Moodie

Keith Beacham

Derek Nesset

Paul Rodgers

Russell P Davey

Ian D Henning

Matthew Webster

A communications network has a communications station, such as a telephone exchange, and at least one interface, such as a cabinet. A plurality of optical carriers are provided between the exchange and a cabinet, thereby allowing modulation of the signals, for example xDSL modulation, to be carried out at the exchange, rather than at the cabinet. This arrangement reduces the need to power the cabinet.

Broadband communications

A communications system connects one or more BTS hotels with several remote access nodes on a transmission ring. Each operator has one or more separate optical wavelengths. Signal flow around the ring can either be uni-directional or bi-directional. Each optical wavelength (or wavelength pair) contains the wireless signal traffic for all remote nodes in the ring for the operator using that particular wavelength in digital form. At each node, the incoming signals are electrically demultiplexed and appropriate signals for that node are extracted for conversion to RF. These signals are copied rather than cut so that they are also available at following remote antenna nodes, thereby enabling simulcast operation.

Wireless signal distribution system and method

The present invention allows remote antenna units for radio frequency signal transmission and receipt to operate without the requirement for remote electrical power supplies or for connecting cables that incorporate electrical conductors. According to an aspect of the present invention, an optical communications system employing radio frequency signals comprises a central unit; at least one remote unit having at least one optoelectronic transducer for converting optical data signals to radio frequency signals and converting radio signals to optical signals and at least one antenna to receive and send radio frequency signals; at least one optical fiber data link between the central unit and the remote unit for transmitting optical data signals therebetween; and at least one optical fiber power link between the central unit and the remote unit for providing electrical power at the remote unit.

Optical fiber communications method and system without a remote electrical power supply

A switch for the switching of communications system signals, with m input ports and n output ports, comprising two or more parallel switch matrices, each of size m&#xd7;n, combined so that each switch matrix contributes to the available output power at each output port. The failure of one of the switch matrices, or one of the transmission paths therein, will therefore result only in a small reduction in the output power at the relevant output port, rather than complete power loss as would be the case for a conventional switch This fault condition can be detected using a power imbalance detection circuit in the switch matrix combiner. Additionally, the fault condition, having been detected by the power imbalance detection circuit, may be temporarily compensated by an automatic level control system.

Resilient switch

A signal distribution system for distributing signals, such as for outdoor wireless networks, comprises a number of remote hubs, each of which can direct wireless signals to a number of antennas. The antennas are used to provide wireless service to the service users, such as mobile units, within their geographic coverage area. The remote hubs are connected to main hubs, which are usually located centrally. Each main hub can support a number of remote hubs. The main hubs are connected to a number of base stations (again usually located centrally) in a flexible and re-configurable manner using a switch matrix. Some remote hubs may also include switched matrices for a further level of signal routing.

Communications system and method

A transducer for use in a hybrid optical and radio communications system includes a zero electrical power photodetector and a radio antenna. The photodetector is electrically connected to the radio antenna so that, in use, optical signals are received and radio signals are transmitted by the transducer without the use of electrical power. The transducer can thus be remotely sited at locations in communications systems not having a supply of electrical power. In a first embodiment the photodetector includes a zero-bias photodiode, and in a second embodiment the transducer includes a self-biasing photodetector.

Transducer

Generation of radio frequency modulated optical radiation

An optical communication system used for the distribution of a signal includes a central station having an optical source. One or more remote stations are connected to the central station by an optical network. The central station outputs onto the network a carrier signal and an intermediate frequency signal. The remote station includes an optical mixer/detector which mixes the carrier and intermediate frequency signal both in the optical domain and outputs an RF electrical signal. The optical mixer/detector may be a heterojunction bipolar phototransistor (HBT). The optical source in the central station may be a dual-mode semiconductor laser.

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Ipswich, United Kingdom

David Wake