Aceaxis Limited

Nortel Networks Corporation

Apple Inc.

Ciena Corporation

David Damian Nicholas Bevan

Simon John Gale

Fiona Wilson

John Edward Hudson

Steven John Baines

Christopher John Reed

Francis Giles Overbury

Kim Bryon Roberts

James St Harley

Martin Stevens Smith

James Mark Naden

Andrew Urquhart

Julius Robson

Stephen Cooper

Manoj Verghese

Kevin Malcolm Kelly

Julius George Robson

Nigel Chapman

A location is identified of at least one PIM (passive intermodulation) source in a frequency selective device by applying an excitation waveform to the frequency selective device and measuring a PIM response signature of the frequency selective device. The PIM response signature is a characteristic of PIM produced in response to the excitation waveform. The measured PIM response signature is compared with each of a plurality of example PIM response signatures, each of the plurality of example PIM response signatures corresponding to a characteristic of PIM expected for a respective location of a PIM source in the frequency selective device. The location of the at least one PIM source within the frequency selective device is determined on the basis of the comparison.

Location of a source of passive intermodulation in a frequency selective device

A method of processing interference received in a wireless network, the interference comprising a non-linear product of at least one downlink signal of the wireless network, is provided. The method includes intercepting a plurality of optical links, each optical link being between a respective baseband processing unit of a plurality of baseband processing units and a respective radio head of a plurality of radio heads, to provide a plurality of downlink and uplink data streams. The method includes detecting interference in an uplink data stream representing signals received at a first uplink carrier frequency caused by non-linear products of at least a signal at a first downlink carrier frequency represented by a downlink data stream. The method includes generating an indication comprising information relating to an uplink carrier frequency experiencing interference and at least one downlink carrier frequency causing interference.

Processing interference due to non-linear products in a wireless network

A PIM (passive intermodulation) diagnosis is generated for one or more wireless networks which have equipment deployed at a plurality of cell sites. Data is received representing PIM detection results from PIM detection devices at the cell sites, the detected PIM including PIM caused by passive intermodulation between carriers of the one or more wireless networks. The data representing respective PIM detection results is normalized to account for transmission power and frequency allocation of respective cell sites, and the normalized data representing respective PIM detection results is correlated with data relating to a condition of respective cell sites and/or an environment of the respective cell sites to produce correlation results. The PIM diagnosis is generated in dependence on the correlation results.

Processing of passive intermodulation detection results

Interference to a received signal is reduced in a wireless network, the interference comprising intermodulation products of at least a first signal and a second signal. Delayed interference signals comprising simulated intermodulation products are generated on the basis of the first signal and the second signal using a range of differing delay values and each of the delayed interference signals is correlated with the received signal to produce data representing a correlation for each delayed interference signal. At least one delay value is selected in dependence on a the data representative of the correlations and an interference signal comprising simulated intermodulation products generated from the first signal and the second signal using the at least one delay value is combined with the received signal.

Method and apparatus for processing of intermodulation products

Interference comprising an intermodulation product of at least a first signal and a second signal is detected in a wireless network, by generating, on the basis of at least the first signal and the second signal, at least one interference signal comprising a simulated intermodulation product and correlating the at least one interference signal with a waveform received in the wireless system to produce data representing a correlation. The presence of an intermodulation product of at least the first signal and the second signal is detected in the interference in dependence on the data representative of the correlation.

Method and apparatus for detection of intermodulation products

Interference comprising a passive intermodulation (PIM) product of at least a first signal and a second signal is detected in a wireless network, by generating, on the basis of at least the first signal and the second signal, at least one interference signal comprising a simulated intermodulation product and correlating the at least one interference signal with a waveform received in the wireless system to produce data representing a correlation. The presence of an intermodulation product of at least the first signal and the second signal is detected in the interference in dependence on the data representative of the correlation.

Method and apparatus for reduction of intermodulation products

System and methods of cellular communications network are described herein. In one system, an antenna array is described. The antenna array has a first beamforming arrangement for producing uplink beams and a second beamforming arrangement for producing downlink beams. The first and second beamforming arrangements are different from one another. The wireless communication network communicates with a mobile station by use of the uplink and downlink beamforming arrangements.

Downlink and uplink array and beamforming arrangement for wireless communication networks

In a decoder implementing a belief propagation algorithm for iteratively decoding a Low Density Parity Check (LDPC) encoded data block, a method of computing messages to be sent by a first node of the decoder to at least one neighbor node of the decoder. The method comprises: processing messages received by the first node to remove an echo of a previous message sent by the first node to the at least one neighbor node in a previous iteration, to yield corresponding modified messages; computing a message for a current iteration using the modified messages; and broadcasting the computed message for the current iteration to each of the at least one neighbor nodes.

Low density parity check (LDPC) decoder using broadcast messaging

The invention is directed to a method of synchronising transmission between two nodes in a wireless network. The method comprises the steps of obtaining an expected interference profile for each node; and agreeing a synchronised transmission schedule between the nodes, where the expected interference profile of each node meets predetermined criteria.

Wireless communication

Soft-handoff methods involve receiving an uplink signal from a user equipment at more than one basestation. The uplink signals are processed at each basestation before being backhauled to a common point for use to derive a single signal from the user equipment. One problem with previous types of soft-handoff methods is that relatively complex processing is required at each basestation in order to demodulate and decode the signals. It is also desired to further increase uplink capacity as compared with known types of soft-handoff methods. This is achieved by backhauling signals without carrying out any decoding of the uplink signal at the basestation. The backhauled signals are combined at a common point using maximal ratio combining before being fully demodulated and decoded. As a result capacity is increased and required user equipment transmit power is reduced.

Soft handoff method for uplink wireless communications

In a cellular mobile telecommunications system the position of a mobile station can be estimated in terms of its bearing and range from a cell site. A multi-element direction finding antenna at the cell site receives signals from the mobile station and a receiver circuit estimates the bearing using the relative phase of signals received at different antenna elements and estimates the range by measuring round trip delay of signals to and from the mobile station. Motion of the mobile station can introduce errors into the bearing estimate due to frequency offset and frequency spread when element sampling is non-simultaneous. Compensation for these errors is introduced by using signal samples successively received at the same antenna element to estimate Doppler frequency offset and spread. It is necessary to ensure accurate calibration of the direction finding antenna and the receiver circuit. This is done by injecting calibration signals into the circuit near the antenna or into the antenna itself from a near field probe. Other aspects of calibration, such as antenna position, are calibrated using a remote beacon. A beacon emulating a mobile station but at a fixed, known location, or a beacon at an adjacent cell site may be used.

Position location method and apparatus for a mobile telecommunications system

A base station of a cellular communications system forms a plurality of adjacent overlapping beams in azimuth across a coverage area, and the position of the plurality of beams is varied in unison about a rest position whereby to provide a mean antenna gain in all azimuthal directions across the coverage area and to minimise cusping loss. The position of the beams can be varied by a movement in azimuth over one half, or multiples of one half, of the angular separation of the formed beams. Preferably there are a plurality of base stations in the system, each of whose plurality of beams are varied in position independently of the other base stations. The beams can be varied at a rate which is substantially equal to the rate of variation of one of the effects normally experienced by a terminal, and which the system operator incorporates a margin to accommodate.

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Harlow, United Kingdom

David Damian Nicholas Bevan