426 results about "Rake receiver" patented technology

Closed loop wireless communication of signals using an adaptive transmit antenna array (3), in which a plurality of copies of signals to be transmitted by the transmit antenna array (3) are produced with delays and weights (w_n^j) that are functions of the multi-path transmission channel characteristics (H) from the transmit antenna array (3) to a receive antenna array (4) of a receiver (2) and are combined before transmission by the transmit antenna array. The delays and weights (w_n^j) of the transmit copies for each transmit antenna element are functions of the respective multi-path transmission channel characteristics $\left(h_{n,m=1}^{l=1},\dots ,h_{n,m=M}^{l=L}\right)$

from that transmit antenna element to the receive antenna array (4) ssuch that the multi-path signal components propagated to each receiver element are received with distinguishable delays according to the propagation path. The receiver (2) combines the received signal components from each receive antenna element with delays and weights (u) that are respective functions of the multi-path transmission channels.

Preferably, the receiver comprises a multi-finger RAKE receiver (6) that copies the received signals from the receive antenna array with delays and weights (u) that are respective functions of the multi-path transmission channels and combines the copied received signals.

A system and method for canceling interference present in a code-division multiple access (CDMA) channel signal received at a CDMA receiver that is caused by multipath components of a transmitted pilot channel signal or by soft handoff conditions is computationally efficient because it operates at symbol rates. The channel signal from which such multipath interference is canceled can be either a traffic (data) channel or the pilot channel itself. Interference signals are produced in groups corresponding to the fingers of the CDMA rake receiver. The interference signals corresponding to each finger are used to cancel interference in the other fingers.

A WCDMA system includes a Base Station (BS) or forward transmitter and a pilot channel that transmits control signals between a Mobile Station (MS) and BS to reconfigure their transmitter/receiver according to the prediction of the channel power and channel power probability density function separated into three distinct equal probable regions. Data signals are encoded using a one-half Viterbi encoder and interleaved. The interleaved data bits are modulated using Quadrature Phase Shift Keying (QPSK) modulation. The QPSK data is multiplexed with the pilot channel and spread by an appropriate code in an OFDM transmitter modified by a long code. Output of the transmitter may be provided to two diverse antennas for reliable communications to the receiver. Data may be received at two diverse antennas. The outputs are provided to match filters coupled to a coherent rake receiver and a channel prediction system. The future attenuation of the channel coefficients and power are determined by the prediction system for several milliseconds. The power levels of each finger in the Rake receiver can be predicted and the strongest ones used in determining the optimum transmitter power or rate control for operating the system transmitters and receivers based on computing a long range power prediction of each finger of a rake receiver.

A wireless repeater and method for managing air interface communications is provided. A repeater may include a donor antenna, a coverage antenna, a mobile station modem, a processor, and data storage. The donor antenna will receive a plurality of air interface beams on the forward link from a radio access network. The coverage antenna will pass each forward link beam received to a mobile station being served by the repeater. Further, the donor antenna will pass each forward link air interface beam to the MSM, where the MSM will apply a rake receiver to identify a signal characteristic of the forward link of each beam received, and the processor will record in the data storage the signal characteristic corresponding to each beam. Given this data, the repeater will select an air interface beam with the most preferable signal characteristic, and will keep only this beam active for reverse link communications.

A wireless communication receiver, such as the receiver included in a wireless communication transceiver implemented in a base station or in a mobile station of a wireless communication network, includes a parametric G-RAKE receiver circuit and a method that compute parametric scaling parameters on a per transmission interval basis. In one embodiment, measured impairment correlations are obtained for an individual transmission slot and used to estimate instantaneous values of the scaling parameters. One or both of those instantaneous values are then constrained according to one or more defined limits. In other embodiments, multiple transmission slots are used to increase the number of measurements available to estimate the scaling parameters, with parameter constraining optionally applied. Further embodiments use iterative methods and/or solve for one parameter, and use the results to obtain the other parameter(s). One or more of these embodiments can be improved through the use of error correction/detection information.

A multistage adaptive parallel interference canceller is disclosed. The multistage adaptive parallel interference canceller for a downlink receiver includes: a plurality of stages of interference cancellation units. Each of interference cancellation units includes: a matched filter for matching a signal from a rake receiver each channel signal and generating a matched signal; a soft decision unit of which a slope is monotonically increased, for performing soft decision of the matched signal and generating a soft-decided signal; a weight controller for controlling the slope of the soft decision unit; a respreader for respreading the soft-decided signal based on a walsh code and a scrambling code and generating a respread signal; an interference calculator for calculating interference signals due to another user signal and multipath signals; and an interference canceller for canceling the interference signals from an input signal received in the rake receiver.

Interference, such as inter-symbol interference, from a symbol of interest in a RAKE receiver is reduced. The RAKE receiver comprises a plurality of RAKE fingers, a processor, and a combiner. The plurality of RAKE fingers despread symbols received over multiple paths of a multi-path channel. The processor determines cross-correlations between symbol waveforms from different symbols and multiple paths. The combiner combines the despread symbols using the cross-correlations to reduce interference from the symbol of interest.

In one embodiment, an HSDPA co-processor for 3GPP Release 6 Category 8 (7.2 Mb/s) HSDPA that provides all chip-rate, symbol-rate, physical-channel, and transport-channel processing for HSDPA in 90 nm CMOS. The co-processor design is scalable to all HSDPA data rates up to 14 Mb/s. The coprocessor implements an Advanced Receiver based on an NLMS equalizer, supports RX diversity and TX diversity, and provides up to 6.4 dB better performance than a typical single-antenna rake receiver. Thus, 3GPP R6 HSDPA functionality can be added to a legacy R99 modem using an HSDPA co-processor consistent with embodiments of the present invention, at a reasonable incremental cost and power.

Methods of recovering information encoded in a spread spectrum signal transmitted according to a spreading sequence in a communications medium are provided in which a spread spectrum signal is received from the communications medium and correlated with a spreading sequence to produce a plurality of time-offset correlations. Some of these time-offset correlations may be designed to cancel out known interfering signals. A subset of the plurality of time-offsets may then be selected, and corresponding traffic correlations may then be combined using a weighted combination to estimate information encoded in the transmitted spread spectrum signal. Receivers for implementing these methods are also provided.

The method for compressive sensing (CS) and reconstruction of ultra-wideband (UWB) channels includes building four practically-based dictionaries related to the antenna angles of transmission and angles of arrival that enhance the sparsity of UWB signals. The dictionaries account for the practical effects of the channel, such as pulse dispersion and the unavoidable effects of the antenna. Utilizing the practically-based dictionaries CS is able to reconstruct the UWB signals more efficiently with reasonable complexity. In addition to waveform reconstruction, the dictionaries are used for channel estimation. The CS method can be used with either a single-shot full profile correlator or a Rake receiver. The Rake receiver employs CS in adjusting its parameters to take advantage of the energy available in the strongest propagation paths.

The present invention is related to a Rake receiver (R1) for receiving a radio signal and to a searcher (S8a, S8b) for estimating the delay profile of one or more radio links. The searcher includes means for estimating delay profiles in separate windows. The searcher is arranged for being switched into a single window mode or alternatively into a multiple window mode. In single window mode the delay profiles of separate radio links are estimated in the windows, while in multiple window mode two or more windows are allocated adjacent in time for estimating the delay profile of the same radio link. Thereby, the use of the resources of the searcher can be adapted to the radio environments in which the searcher will be used. The Rake receiver comprises fingers that are grouped into two sets. Within a set of fingers the propagation paths are time aligned. The output from the two set of fingers are time aligned and then combined.

A radio receiver is described that processes multiple wireless standards using a single antenna according to embodiments of the invention. The radio receiver includes a single antenna, and a low noise amplifier that is connected to the antenna, without an intervening power divider or power splitter. The output of the low noise amplifier feeds multiple wireless receivers in a parallel arrangement that are operating according to different communications standards, including for example a Bluetooth receiver, and a WLAN 802.11 receiver. Additional wireless standards and their corresponding receivers could be added as well. The input impedance of the low noise amplifier defines the impedance seen by the antenna, regardless of which operational standard is actually in use. Since the input impedance of the low noise amplifier is substantially independent of whether the Bluetooth or WLAN paths are ON or OFF, simultaneous operation can be accomplished.

In a RAKE receiver capable of detecting and combining a plurality of multipath signals, a controller for managing the assignment of the plurality of multipath signals to fingers of the RAKE receiver. The controller determines a phase difference between a selected multipath signal and a first multipath signal assigned to a first finger of the RAKE receiver and does not assign the selected multipath signal to a second finger of the RAKE receiver unless the phase difference is greater than one-half chip. If the phase difference is less that one-half chip, the controller assigns the stronger of the selected multipath signal and the first multipath signal to the first finger of the RAKE receiver. If the finger power falls below a certain threshold, the finger internal states (viz. channel estimate and delay estimate) are maintained while the output of the finger is not processed. If the finger power exceeds the threshold anytime within a specified time interval, the normal activities of the finger are restored. If the power remains lower than the threshold for that time period, the finger is deactivated.

Correlations between the received signal to which pilot symbols have been applied at the transmitter end, and a correlation signal which contains the pilot symbols are carried out in the receiver in order to determine a path delay profile. Averaging processes are carried out over two or more delay profiles obtained in this way. Evaluations are carried out in one or more threshold value selection units (22.1, 22.2) on two or more averaged delay profiles with the aim of path selection. The parameters which govern the correlations and/or the averaging processes and/or the evaluations, and/or the repetition interval of these calculations are set as a function of the relative speed between the transmitter and the receiver, the frequency error between the carrier frequency of the received signal and the reference frequency that is set at the receiving end, and the noise level of the received signal. In the case of reception from two or more base stations, a final path selection is made in a finger allocation unit (40).

Methods and systems for processing signals in a wireless communication system are disclosed. Aspects of the method may include calculating at a receiver, a plurality of signal-to-interference-plus-noise ratio (SINR) values for a wireless signal, which is received from a transmitter, based on a corresponding plurality of weight values. A maximum one of the calculated plurality of SINR values may be determined. At least one weight value including one of the corresponding plurality of weight values may be fed back to the transmitter. The at least one weight value including one of the corresponding plurality of weight values may be associated with the determined maximum one of the calculated plurality of SINR values. The at least one weight value including one of the corresponding plurality of weight values may be communicated to the transmitter via at least one downlink communication channel.

A method for performing a third cell search process or a multi-path search process to detect a scrambling code used by a Node B or in a Mobile Station by generating at least one scrambling code; determining one of first and second methods, in which the first method calculates correlation energy values of reception signals associated with at least two scrambling codes sequentially generated with predetermined time delays, and the second method sequentially generates one scrambling code with the predetermined time delays, and calculates correlation energy values of the reception signals associated with the generated scrambling codes; calculating correlation energy values of the reception signals associated with the generated scrambling codes according to the determination result; and determining a scrambling code used by the Node B or multi-paths to be assigned to individual fingers of a rake receiver using the calculated correlation energy values associated with the scrambling codes.