Abstract:
A code division multiple access communication system transmits a pilot and traffic signal over a shared spectrum. The pilot and traffic signal have an associated code and are received over the shared spectrum. The received signals are sampled and the samples are delayed to produce a window. A weighted value for each despread pilot code window sample is determined using an adaptive algorithm. Each window sample is despread with a traffic code. Each despread traffic code window sample is weighted according to a weight corresponding to its respective pilot code sample.
Abstract:
A base station for carrier offset recovery. An adaptive matched filter produces a filtered signal. A rake receiver provides relative path values of multipath components. A mixer generates channel impulse response estimates. A channel despreader despreads the filtered signal using the pseudo-noise signal generated to produce a despread channel signal of the selected channel. A pilot channel despreader despreads the filtered signal using a pseudo-noise signal generator to produce a despread pilot signal of the pilot channel. A hard decision processor determines a symbol value of the despread channel signal. A complex conjugate processor generates a complex conjugate of the symbol value as a correction signal. A phase-locked loop produces a phase correction signal to recover carrier offset.
Abstract:
An improved base station which cancels the effects of known fixed interference sources produces a signal substantially free from the interference sources thereby increasing total channel capacity. The adaptive interference canceller base station includes a main antenna for receiving signals from other communication stations and at least one directional antenna directed toward an interference source. The main and directional antennas are coupled together such that an output signal substantially free from the interference is generated.
Abstract:
A base station transmits a first spread spectrum signal having a first code. It receives and analyzes an impulse response of multipath components of a second spread spectrum signal having a second code to determine a first received component. The second signal is time synchronized with the first spread spectrum signal. A distance determination is made based on in part a timing difference between the second code of the received second signal and the first code of the base station's transmitted first signal and the determined first received components for that base station's received second signal.
Abstract:
A transmitter transmits a spread spectrum pilot and data signal. Each signal has an associated chip code. A receiver receives the transmitted pilot and data signal. The received pilot signal is filtered using the pilot chip code and weights are determined for components of the received pilot signal using an adaptive algorithm. The received data signal is weighted by the determined weights and filtered with the data signal chip code to recover data from the received data signal.
Abstract:
Systems and methods are provided for determining a direction of a signal received at an antenna array. An antenna array includes a plurality of antenna elements, including a reference element. A signal combiner element is configured to combine weighted signals from a subset of the plurality of antenna elements to provide a composite output. An adaptive processing component is configured to determine an optimal set of weights for the subset of the plurality of antenna elements. An angle of arrival search component is configured to find a direction of minimum gain given the optimal set of weights.
Abstract:
A code division multiple access communication system transmits a pilot and traffic signal over a shared spectrum. The pilot and traffic signal have an associated code and are received over the shared spectrum. The received signals are sampled and the samples are delayed to produce a window. A weighted value for each despread pilot code window sample is determined using an adaptive algorithm. Each window sample is despread with a traffic code. Each despread traffic code window sample is weighted according to a weight corresponding to its respective pilot code sample.
Abstract:
A receiver includes a plurality of antennas; a plurality of front end circuits producing digital signals in response to signals received on the antennas; a beamforming unit weighting and summing the digital signals to produce a first signal; a first stage including a first plurality of modems producing first bit streams in response to components of the first signal, a first plurality of signal reconstruction units producing first signal replicas in response to the first bit streams, and a first active cancellation unit weighting the first signal replicas and subtracting the weighted first signal replicas from the first signal to produce a second signal; and a second stage including a second plurality of modems producing second bit streams in response to components of the second signal, a second plurality of signal reconstruction units producing second signal replicas in response to the second bit streams, and a second active cancellation unit weighting the second signal replicas and subtracting the weighted second signal replicas from the first signal to produce a third signal. A method implemented by the receiver is also provided.
Abstract:
A code division multiple access communication system has a base station with a plurality of transmitting antennas. From each transmitting antenna of the base station, a pilot signal is transmitted having a different chip sequence than the other transmitting antenna. At a user equipment, the transmitted pilot signals are received from each transmitting antenna. A weight adjustment is derived in response to the received transmitted pilot signals. The user equipment transmits the weight adjustment to the base station. The transmitted weight adjustment is received from the user equipment. A data signal is processed to produce a plurality of versions of the data signal. At least a portion of each processed data signal has a different chip sequence than the other processed data signal version. At least one processed data signal version is weighted by a weight value adjusted in response to the received transmitted weight adjustment. From each transmitting antenna, a different one of the data signal versions is transmitted and the transmitted data signal versions are received at the user equipment.
Abstract:
A base station comprises a plurality of antennas. Each of the antennas is separated by a known distance. A first spread spectrum signal is transmitted having a first code. Using the plurality of antennas, a second spread spectrum signal is received having a second code. The second spread spectrum signal is time synchronized with the first spread spectrum signal. A distance determination is made based on in part a timing difference between the second code of the received second spread spectrum signal and the first code of the base station's transmitted first spread spectrum signal. A phase difference of a carrier signal of the second spread spectrum signal as received by each of the plurality of antennas is compared. An angle of the received second spread spectrum signal is determined using the known distance between the antennas and the phase difference. A location of a source of the second spread spectrum signal is determined using the determined angle and the distance determination.