British Telecommunications Corporation

Khalifa University

Emirates Telecommunications Corporation

British Telecommunications Public Limited Company

Nayef Alsindi

James Aweya

Kin Poon

Zdenek Chaloupka

This invention relates to methods and devices for bias estimation and correction, particularly for time-of-arrival (TOA) based wireless geolocation systems. Multipath and non-line-of-sight (NLOS) biases can cause distance estimation errors in the range of tens-hundreds of meters and is particularly problematic in urban and indoor environments. The behavior of the biases dynamically changes depending on the clutter and/or obstructions between the base station and the mobile device. Aspects of the present invention provide practical real-time bias estimation and correction techniques for TOA-based systems and are based on inferring and estimating the biases from dynamic time differential measurements. The techniques can operate in real-time and involve simple calculations.

Methods and devices for bias estimation and correction

This invention relates to methods and devices for channel identification. The invention is particularly concerned with techniques for non-line of sight channel identification. In embodiments of the invention the methods and devices are used for channel identification in wireless geolocation systems. Embodiments of the invention make use of an entropy estimation of the channel to distinguish channel conditions and in particular to identify line-of-sight and non-line-of-sight channels and which can be used to solve the NLOS problem of determining relative distances between transmitter and receiver. In particular embodiments an entropy estimation of the channel impulse response (CIR) is used to construct a robust entropy-based channel identification technique. As a result, more accurate localization in indoor and other multipath environments may be possible.

Methods and devices for channel identification

This invention relates to methods and devices for motor speed control. The invention has particular application in the control of motors over packet networks. In embodiments of the invention, phase-locked loop principles are used to remotely control the speed of an electric motor over a packet network. The setpoint for the motor is supplied by arriving timestamps from a speed-mapped variable frequency source. The shaft speed of the motor is measured with a tachometer with its output proportional to the motor speed. Any deviation of the actual speed from the setpoint is amplified by the power amplifier whose output drives the motor. Speed control over packet networks allow smoother operation of a process, acceleration control, different operating speeds for each process recipe, compensation for changing process variables, slow operation for setup purposes, adjustments to the rate of production, accurate positioning, and control torque or tension of a system.

Method and system for motor speed control

This invention relates to methods and devices for clock offset and skew estimation. The invention has particular application in the alignment of slave clocks to a master clock. In embodiments of the invention, the slave clock employs an independent free running clock and a recursive estimation technique to estimate the clock offset and clock skew between the slave and master clocks. The slave can then use the offset and skew to correct the free running clock to reflect an accurate image of the master clock.

Method and system for clock offset and skew estimation

This invention relates to methods and devices for entropy-based location fingerprinting, in particular for use over wireless local-area networks (WLANs). The invention has particular application in localization for indoor environments. In embodiments of the invention, an entropy-based fingerprint is determined at a number of predetermined locations within the desired area of localization during an off-line phase and subsequently used in an on-line mode to determine the location of a receiver. In particular embodiments, the fingerprint is a vector of entropy estimates of the channel transfer function (CTF) between a mobile terminal and all access points within coverage. The invention seeks to provide a fingerprinting localization solution that has a simplicity of structure, leading to advantages in storage and pattern recognition requirements, and robustness by proving a unique measure of information that is related to the channel experienced at the location of the mobile terminal.

Method and system for localization

This invention relates to methods and devices for clock synchronization. The invention makes particular use of IEEE 1588 with offset and skew correction. In embodiments of the invention, the IEEE 1588 Precision Time Protocol is used to exchange time stamps between a time server and a client from which the client can estimate the clock offset and skew. In embodiments of the invention a free running clock at the client is provided with an estimation technique based on the time stamps from the IEEE 1588 PTP message exchange between the server and client clocks. The offset and skew from the estimation process can be combined with the local free running clock to give a synchronized local clock which is an accurate image of the master clock.

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Abu Dhabi, United Arab Emirates

Nayef Alsindi