British Telecommunications Corporation

Khalifa University

Emirates Telecommunications Corporation

British Telecommunications Public Limited Company

Ivan Boyd

James Aweya

Zdenek Chaloupka

Daniel Kenneth Freeman

Stephen A Cassidy

Robert M Claxton

Di Wang

Ahmad Al-Rubaie

Jason Ng

Stephen Anthony Cassidy

Robert Michael Claxton

This invention relates to methods and systems for searching. It is particularly applicable to methods of searching which enable efficient identification of compatible portfolios. Embodiments of the invention propose methods of searching which address the huge search space issue associated with identifying compatible portfolios. In particular, embodiments of the invention start their search operations simultaneously from both sides by both trying to form valid portfolios from candidate products until a valid solution is found and trying to find conflicts from the defined compatibility rules until a conflict is found which leads to the conclusion that no valid solution exists. A conclusion from either process will stop the whole searching process which can significantly reduce blind and unnecessary searching in the whole search space. In embodiments of the invention, the two sides of the search process are also connected in a way which permits two-way communications between the processes to share information about invalid search branches during the execution of the search. The shared information is then used to direct the current and later stage of search execution. Such exchange of information can also significantly reduce the search space and create more efficient searching systems and methods, particularly by stopping search agents from carrying out invalid future searches in branches that another agent has already identified as invalid.

Methods and systems for searching

This invention relates to methods and devices for timing synchronization. The invention has particular application where timing is being carried out over packet networks using, for example, the IEEE 1588 Precision Time Protocol (PTP). Embodiments of the invention make use of estimated forward and reverse path delay asymmetries directly in the estimation algorithm (for example a Kalman filter). This can allow the variation in the timestamps which have been compensated for the delay asymmetry to be significantly reduced, which can reduce the complexity of the phase offset estimation algorithm.

Methods and systems for synchronization using delay asymmetry

This invention relates to methods and systems for estimating skew based on, for example, the IEEE 1588 Precision Time Protocol (PTP). These methods and systems can allow the clock skew between a master clock (server) and slave clock (client) exchanging PTP messages over a packet network to be estimated more rapidly than conventional estimation techniques and thereby improve the convergence of standard estimation algorithms. In one embodiment, the skew estimation is derived from a set of timestamps from a message exchange between the master and slave using a non-linear least square-fitting algorithm. An example of the fitting algorithm is the Levenberg-Marquardt algorithm.

Systems and methods for estimating skew

This invention relates to the use of frequency synchronization accuracy as an additional quality metric for mobile call handover between base stations. Call handover is of major importance within any mobile network; without checking frequency synchronization before handover dropped calls and interrupted communication can result.

Methods and systems for estimating frequency synchronization accuracy

This invention relates to methods and systems for estimating and checking synchronization accuracy, in particular frequency synchronization accuracy. It is particularly applicable to synchronization methods and systems which involve a digital phase-locked loop (DPLL) and embodiments provide methods and systems for estimating and tracking how well the DPLL is frequency synchronized to a source frequency. In one embodiment, frequency synchronization accuracy is used as an additional quality metric for mobile call handover between base stations. Call handover is of major importance within any mobile network; without checking frequency synchronization before handover dropped calls and interrupted communication can result.

This invention relates to methods and systems for estimating skew based on, for example, the IEEE 1588 Precision Time Protocol (PTP). These methods and systems can allow the clock skew between a master clock (server) and slave clock (client) exchanging PTP messages over a packet network to be estimated. In one embodiment, the slave employs a digital phase-locked loop (DPLL) driven by timestamps supplied from a master clock. The slave is able to process the timestamp information embedded in PTP Sync and Follow_Up messages in order to lock its frequency to that of the master clock. In certain embodiments a frequency locked DPLL and a local free-running counter are used to estimate the skew of the local slave oscillator.

Methods and systems for estimating skew

A user accesses a destination such as a call center. The call center generates a record for insertion into the user's personal address book, with a telephone number of the center and metadata concerning a transaction. To place a later call on the same matter, the user selects, either using his telephone or via a separate terminal, the address book entry and the call is made. The center receives the user's telephone number via the calling line identity (CLI) and translates this into a data address so that it can 'pull' the metadata from the personal address book. Alternatively the server can translate the center's telephone number into a data address to 'push' the metadata to the center.

Telecommunications calls

The invention is concerned with the transmission of broadband signals onto to a telephony connection having constraint profile limiting the maximum allowed power as a function of frequency. As a result, broadband signals can be delivered using low power equipment to a telephony line whilst respecting the constraint profile associated with that line.

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Ipswich, United Kingdom

Ivan Boyd