British Telecommunications Public Limited Company

British Telecommunications Corporation

Vodafone IP Licensing Limited

Kevin Smith

Julian Kazimierz Lucek

David Graham Moodie

Derek Nesset

Paul Gunning

Danny Robert Pitcher

David Cotter

Keith J Blow

Andrew David Ellis

David C Rogers

Justin Kang

Terence Widdowson

Russell P Davey

Yu R Zhou

Terrence Widdowson

Davey Russell

Mark Wilkinson

Elaine J Greer

Julian Kazimirez Lucek

Monica De Lacerda Rocha

Daniel Moutinho Pataca

Yu Zhou

The present invention provides a method of indirectly determining the optical signal-noise ratio of an optical fibre communications link. In a test environment, the relationship between OSNR and pre-FEC BER (forward error-corrected bit error rate) is determined for a particular type of optical transponder. When a transponder of that type is connected to an optical communications link then the pre-FEC BER can be measured and the OSNR inferred from the pre-determined OSNR-BER relationship. The OSNR value can then be used to select a transponder modulation format or other transmission parameters.

Optical communications

A mobile telecommunications network includes a plurality of nodes for wireless communication with a mobile telecommunications device and a respective server associated with each of said nodes, each server having processing functions, wherein a processing function of a first one of the servers associated with a first one of the nodes is operable to support a communication session with the mobile telecommunications device to provide a service thereto. The processing function of the first one of the servers is operable to send data relating to the communication session to a second one of the servers associated with a second one of the nodes for use by a processing function of the second one of the servers to enable the processing function of the second one of the servers to support the communication session and provide continuity of the communication session if the mobile telecommunications device moves from registration with the first one of the nodes to the second one of the nodes.

Telecommunications network communication sessions

A PON in which parallel optical fiber paths are provided between dual OLTs and the ONTs, one of the optical fiber paths providing an active connection and the other optical fiber path providing a standby connection. Respective VLANs may be formed over the parallel optical fiber paths. If performance indicators, for example Ethernet continuity check messages, indicate that an ONT is no longer in communication with the OLT then data may be sent via the VLAN associated with the standby connection.

Communications network

An optical network includes a number of nodes coupled to an optical transmission medium, such as an optical fiber bus. Each of the nodes includes a dark pulse generator. Different nodes output dark pulses in different time slots onto the transmission medium, forming a dark pulse OTDM (optical time division multiplexed) signal. The network may have a re-entrant bus topology.

Dark pulse TDMA optical network

An optical pulse source includes a gain-switched semiconductor laser diode. Light from a continuous wave source is opitically coupled into the laser cavity. Light output from the laser cavity passes through an electro-optic amplitude modulator. Synchronized modulating signals are applied to the semiconductor diode and to the amplitude modulator. The source outputs short low-jitter low-pedestal optical pulses and is suitable for use, for example, in a broadband optical network operating at thigh bit rates of 100 Gbit/s or more, or in an optical interconnect.

Optical pulse source

Optical packet processing

Optical pulse seqeunce generator

Dark pulse generation

A receiver at a node in an optical network receives an optical clock signal and an OTDM datastream. A detector converts the clock signal to the electrical domain. A variable delay stage applies a selected delay to the clock signal in the electrical domain. A non-linear electro-optic modulator which may be an electro-absorption modulator, receives the OTDM datastream at its optical input. An electrical control input of the modulator is connected to the output of the variable delay stage. The electro-optic modulator outputs an OTDM channel selected by setting the delay of the variable delay stage. The variable delay stage may include a number of logic gates, particularly AND gates, connected between a pair of microstrip delay lines. The gates are controlled to provide different paths with different corresponding delay times for the clock signal.

Optical network

An optical pulse source includes a gain-switched semiconductor laser diode (1). Light from a continuous wave source (3) is optically coupled into the laser cavity. Light output from the laser cavity passes through an electro-optic amplitude modulator (2). Synchronised modulating signals are applied to the semiconductor diode and to the amplitude modulator. The source outputs short low-jitter optical pulses and is suitable for use, for example, in a broadband optical network operating at high bit rates of 100 Gbit/s or more, or in an optical interconnect.

Growing community of inventors

Ipswich, United Kingdom

Kevin Smith