Abstract: A technique for determining the angles of arrival of signals incident on an antenna array from directions within an angular region of interest involves supplying outputs of antenna elements of the antenna array to a number of different weight generators. Each of the weight generators produces a set of beam-forming weights that maximizes a signal-to-interference ratio of a locally generated signal corresponding to a look angle that is outside the region of interest, with signals at different look angles being supplied to the different weight generators. An annihilation operator is determined from the sets of beam-forming weights generated by the weight generators and from beam-forming vectors representing the look angles of the locally generated signals used in the weight generators. The annihilation operator is applied to a group of beam-forming vectors representing angles within the region of interest to determine angles of arrival of signals within the region of interest.

Abstract: An adaptive algebraic interference cancellation technique for canceling interference from a signal of interest received by an array of antenna elements involves: generating a set of antenna element signals that reflect reception of the signal of interest and interference at the respective antenna elements; adaptively determining the direction of one or more interference sources received with the signal of interest; for each interference source, constructing a directional interference vector corresponding to the direction of the interference source; computing a projection operator that transforms each directional interference vector to a zero vector; applying the projection operator to the antenna element signals to remove interference from the antenna element signals; and restoring the signal of interest by individually compensating the antenna element signals for distortion to the signal of interest cause by applying the projection operator.

Abstract: An adaptive algebraic interference cancellation technique for canceling interference from a signal of interest received by an array of antenna elements involves: generating a set of antenna element signals that reflect reception of the signal of interest and interference at the respective antenna elements; adaptively determining the direction of one or more interference sources received with the signal of interest; for each interference source, constructing a directional interference vector corresponding to the direction of the interference source; computing a projection operator that transforms each directional interference vector to a zero vector; applying the projection operator to the antenna element signals to remove interference from the antenna element signals; and restoring the signal of interest by individually compensating the antenna element signals for distortion to the signal of interest cause by applying the projection operator.

Abstract: Methods and apparatus for improving the effective resolving power of an array antenna are described that are not limited by the physical characteristics of the array. In an array with M elements, up to M?1 directional vectors may be selected, preferably at angles corresponding to the main lobe and/or side lobes of an array antenna beam pattern. A received signal plus interference (s+i) is zero-transformed to eliminate interference received from the plurality of selected directions. The zero-transformed s+i is then restored to obtain the signal of interest observed at maximum gain undisturbed by interference incident from arbitrarily close signal sources. The approach may be combined with conventional beamforming techniques to remove interference incident from angles corresponding to the side lobes, where conventional beamforming techniques are most effective.

Abstract: A method of forming an antenna beam with a phased array antenna having an array of antenna elements includes selecting angular directions at which nulls are to be located in an antenna radiation pattern of the phased array antenna, computing a radiation shaping transformation as a function of the selected angular directions, and determining from the radiation shaping transformation an amplitude and phase distribution over the array of antenna elements that forms the antenna beam with nulls of the antenna radiation pattern at the selected angular directions. Computing of the radiation shaping transformation involves constructing a set of vectors corresponding to the selected antenna radiation pattern nulls, and computing a matrix whose product with each of the vectors is zero. The amplitude and phase distribution is determined from the matrix.

Abstract: The invention is a method for controlling power on multiple forward link communication channels by using multiple power control sub-channels, wherein each power control sub-channel is associated with a forward link communication channel to be power controlled. A fundamental power control sub-channel and a supplemental power control sub-channel are time multiplexed onto a reverse pilot channel. Transmitted over the fundamental power control sub-channel is a fundamental power control bit for indicating to a base station to increase or decrease its transmission power over a corresponding forward fundamental channel. Transmitted over the supplemental power control sub-channel is a supplemental power control bit for indicating to a base station to increase or decrease its transmission power over a corresponding forward supplemental channel. The pilot sub-channels are preferably separated by the fundamental and supplemental power control sub-channels for time diversity purposes.

Abstract: A telephone system including a base station and a mobile unit in communication with each other is provided with an acoustic echo canceler. A sound signal is input. A reference signal that matches the sound signal is formed. A plurality of encoders and decoders receive the reference signal and form a modified reference signal. The plurality of encoders and decoders match a set of encoders and decoders that operate on the sound signal in the base station and the mobile unit. An adaptive filter receives the modified reference signal and forms a replica signal. A subtractor subtracts the replica signal from an echo signal received by the base station.

Abstract: A technique for interference rejection at a sensor array is disclosed that employs a transformation on the output of the sensor array wherein the angular location of the source of each interfering signal constitutes the null-space of the transformation. For a sensor array of M sensor elements, the rejection of up to M-1 interferers is possible with a single transformation. One embodiment of the present invention comprises: receiving M signals, x.sub.0 (t) through x.sub.M-1 (t), at a frequency of .omega. radians/second at a sensor array comprising M spatially-disparate sensor elements, x.sub.0 through x.sub.M-1, wherein the M signals, x.sub.0 (t) through x.sub.M-1 (t), comprise a signal of interest incident on the sensor array at an angle .phi., and an interfering signal incident on the sensor array at an angle .psi..sub.1 ; transforming each of the M signals, x.sub.0 (t) through x.sub.M-1 (t), by a first factor based on .omega., .psi..sub.

Abstract: A multi-dimensional adaptive method and system which can be forced to converge to any predetermined solution of interest. Disturbances are input to the system along with reference signals. Error sensors (detectors) receive the disturbances and the cancelling signals and output error signals. Compensation is determined such that the compensation converges to an arbitrary solution, is not unique and is Hermitian and positive definite.

Abstract: Apparatus for steerable nulling of a radiation pattern of a main lobe and at least one side lobe with at least one null point produced by an antenna array of n elements relative to wideband radio frequency signals having a carrier wave modulated with pulse signals, while receiving the radio frequency signals from, or transmitting to, a desired station and at least one interfering station. An interference rejection processor (IRP) that has n inputs, each connected to a respective element of the antenna array, is connected between the receiver or transmitter and the antenna array. The IRP steers the effect of the antenna radiation pattern such that the at least one null point substantially corresponds to the reception of the radio frequency signal from, or transmission to, the interfering station. The antenna array has an aperture bandwidth, E, such that the IRP is implemented using only phase delay of the radio frequency signals to steer the radiation pattern.