Abstract: A method of detecting and characterising passive intermodulation interference comprises receiving first digital signals representing respective first MIMO signal components transmitted at a first carrier frequency from each antenna of a first group of antennas, receiving second digital signals representing respective second MIMO signal components transmitted at a second carrier frequency from each antenna of a second group of antennas, and receiving third digital signals representing signals received at an antenna under analysis. The first and second digital signals are processed to determine a plurality of partial simulated PIM signals, each being generated from samples of a respective one of the MIMO signal components transmitted from one group of the first and second groups of antennas and from samples of all of the MIMO signal components transmitted from the other group of the first and second groups of antennas.

Abstract: Methods and apparatus are disclosed for processing interference due to passive non-linear products of transmitted signals in a wireless network, and more specifically, but not exclusively, to reduction of interference caused to a receiver due to passive intermodulation (PIM) products generated from at least a first Multiple Input Multiple Output (MIMO) signal comprising first and second MIMO component streams at a first carrier frequency. In other scenarios, there may be two or more carrier frequencies combining to cause PIM, and each carrier frequency may have two or more MIMO component streams.

Abstract: 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.

Abstract: Interference (I1, I2) is mitigated in a waveform received at the input of a receiver in a wireless network, the interference comprising passive intermodulation PIM products of at least a first signal (C1). A first stream of time samples (5) is generated of a simulated first PFM product of at least the first signal (C1), and a second stream of time samples (6) is generated of the simulated first PIM product. The second stream has a delay with respect to the first stream. A replica (8) is generated of the interference by processing (7) at least the first stream and the second stream, the processing comprising reducing a degree of correlation between the first stream and the second stream, and the replica of the interference is combined with a stream of time samples of the received waveform (40) to reduce the interference in the received waveform.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Interference is processed in a waveform received at a device in a wireless network, the received interference comprising non-linear products of at least a first signal (C1) at a first carrier frequency and a second signal (C2) at a second carrier frequency. A complex composite baseband signal is generated comprising at least the first and second signal at baseband, occupying a respective first and second frequency range within a composite baseband frequency range and not overlapping in frequency. The complex composite baseband signal is processed by applying at least a first non-linear function (74a) to generate simulated interference comprising at least one simulated non-linear product. The received interference is then processed in dependence on the simulated interference.

Abstract: Interference (I3) in a waveform received at a device in a wireless network is processed, the processing, for example, being used to detect and/or reduce the interference. The interference comprises non-linear products of at least a first signal. On the basis of at least the first signal, a plurality of interference product streams are generated, each stream comprising a stream of time samples of a simulated non-linear product of at least the first signal. At least two of the plurality of interference product streams are processed to reduce a degree of correlation between said at least two interference product streams thereby producing at least two processed interference product streams, which are correlated with the received waveform to produce a plurality of respective correlation values. The interference is processed in dependence on the plurality of respective correlation values.

Abstract: Interference in a data stream carrying a plurality of uplink signals received in a wireless network is processed, the interference comprising a non-linear product (I3) of at least one downlink signal (C1) of the wireless network. The data stream carrying the plurality of uplink signals and at least a first data stream carrying a plurality of downlink signals is received, and data representing signals received at a first uplink carrier frequency is selected from the data stream carrying the plurality of uplink signals. Data representing signals at at least a first downlink carrier frequency is selected from at least the first data stream carrying the plurality of downlink signals. Interference is detected in the selected data representing signals received at the first uplink carrier frequency by correlation with a synthesized product generated from at least data representing signals at the first downlink carrier frequency.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A digital pre-distortion system which can provide the flexibility to model the highly non-linear distortion associated with High Efficiency RF Power Amplifiers while through a novel implementation of a least squares estimation process allows an implementation well suited for an FPGA application where limited resources and in particular memory resources are available.

Abstract: A digital pre-distortion system which can provide the flexibility to model the highly non-linear distortion associated with High Efficiency RF Power Amplifiers while through a novel implementation of a least squares estimation process allows an implementation well suited for an FPGA application where limited resources and in particular memory resources are available.

Abstract: 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.

Abstract: 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.