Abstract: 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.

Abstract: 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.

Abstract: The present invention relates to radio communication antennas and in particular relates to multi-user detection for CDMA antenna array receivers. Here is provided a method of operating a FDD radio communications system wherein a base station has a constrained beamformer comprising at least two antennas with L channel taps and is operable to maximize diversity gain at the mobile. The total SNR of all the multipath components received at the mobile will be less than for the maximum SNR algorithm, but the diversity gain should outweigh this loss for (nearly) orthogonal channel taps. The performance of an uplink fixed weight beamformer is determined from the correlation matrix of the fadings of the uplink sampled impulse response. Computation techniques are simplified and processing time can be considerably reduced.

Abstract: A method of configuring a plurality of directional beams in a cellular radio system having a plurality of antennas each communicating over a corresponding respective cell area by re-arrangement of directional beams using a same or like carrier frequency to each other, so as to be directed away from each other, and by restricting signal loading on beams experiencing worst case interference. Interference between geographically close cells is reduced by the method resulting in an improvement in carrier to interference ratio performance. Carrier frequencies of the inner two beams transmitted by an antenna are exchanged for the inner two beams which are transmitted in substantially the same direction by another antenna. Inner beams experiencing highest interference are restricted so as to operate at below their maximum signal load in order to reduce interference within the network.

Abstract: A method of allocating channels in a cellular system in which sectored base sites serve subscribers equipped with directional antennas. A plurality of available communication channels is divided into channel subsets. Base sites are arranged in clusters, and within each cluster: the number of channel subsets is equal to the number of base sites, is greater than the number of sectors per base site and is not a multiple of the number of sectors per base site; each channel subset is allocated once in each of the different sector directions; and the allocation pattern is not repeated within the cluster, whereby to minimize co-channel interference.

Abstract: A method and apparatus of reducing interference in a broadband radio frequency link is disclosed. Different signals are received by two antenna elements, in a first case the signals comprise differently polarized signals at the same or an offset frequency; in a second case the signals comprise a wanted signal and an interference signal, wherein the interfering signal is treated as an independent channel. The method comprises the steps of receiving radio frequency signals on two independent paths, selecting a portion of the radio frequency signal in each receive path or the desired signal path after demodulation where a predetermined frequency or band of frequencies is known to be absent; measuring the signal power; determining weights in a feedback path; and applying the feedback control signals to an algorithm which determines the weight(s) applied to the wanted signal such that the signal power in the summed signal(s) due to the interfering signal is reduced or cancelled.