250 results about "Interference canceller" patented technology

A multistage interference canceller and method for removing interference between users and multipath interference from received signals in multiple stages includes a plurality of despreading units which produce a received symbol vector and an estimated channel value, a synthesis unit which synthesizes the received symbol vector, an amplitude of the received symbol vector and the amplitude of the estimated value from each reverse spreading unit, and a decision unit which executes a hard decision and a soft decision according to a result of comparing the total amplitude of the received symbol vector and the total amplitude of the estimated channel value.

A multi-mode receiver includes a channel decomposition module (e.g., a Rake receiver) for separating a received signal into multipath components, an interference selector for selecting interfering paths and subchannels, a synthesizer for synthesizing interference signals from selected subchannel symbol estimates, and an interference canceller for cancelling selected interference in the received signal. At least one of the channel decomposition module, the synthesizer, and the interference canceller are configurable for processing multi-mode signals.

An apparatus and method for interference cancellation in a multi-antenna system are provided. A transmission apparatus includes a channel identifier, a scheduler, an interference canceller, and a transmitter. The channel identifier identifies channel information of each of a plurality of receiving ends located in a service area and neighbor cell interference information on each receiving end. The scheduler selects at least one receiving end. The interference canceller precodes transmitted signals in order to cancel interference between receiving ends located in the same cell and neighbor cell interference. The transmitter transmits the precoded transmitted signals to the selected at least one receiving end.

This invention describes a method for generating noise references for adaptive interference cancellation filters for applications in generalized sidelobe canceling systems. More specifically the present invention relates to a multi-microphone beamforming system similar to a generalized sidelobe canceller (GSC) structure, but the difference with the GSC is that the present invention creates noise references to the adaptive interference canceller (AIC) filters using steerable beams that block out the desired signal when the beam is steered away from the desired signal source location.

An interference canceller between a transmit chain and a receive chain of a transceiver is proposed to complement the action of a diplexer, or duplex filter, that is part of the transceiver. The interference canceller comprises a transmit chain tap, a receive chain coupler for coupling an interference compensation signal into the receive chain, and an interference signal processing path between the transmit chain tap and the receive chain coupler. The interference signal processing path comprises a filter having filtering characteristics similar or corresponding to the filtering characteristic of a receive portion of said diplexer. A corresponding method for interference cancellation is also proposed. Computer-program products for the manufacture of the interference canceller and the execution of the method are also proposed.

A multi-path signal interference cancellation system cancels multiple time delayed signal components of a multi-path interference signal received by a receive antenna and carried on a receiver transmission line of a radio receiver system. The interference cancellation system includes a plurality of adaptive interference canceller circuits, each of which has a synchronous detector, a signal controller and an integrator as essential parts of closed control loops defined by the canceller circuits. The integrator has gain and bandwidth characteristics associated therewith which are adjustable to adjust the gain and bandwidth of each closed control loop. An intensity profile of the multi-path interference signal is generated and stored in a memory. An intensity profile signal from the memory is provided to the integrator of each adaptive interference canceller circuit to adjust the gain and bandwidth of the integrator and the loop in which it is situated to maximize the error detection residual signal-to-noise ratio of each adaptive interference canceller circuit. Each adaptive interference canceller circuit generates a cancellation signal from which a synthesized cancellation signal is generated and effectively injected onto the receiver transmission line to cancel the multiple time delayed signal components of the multi-path interference signal carried thereon so that the radio receiver of the radio receiver system only receives a desired signal.

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.

A DSL or other communication system includes a modem or other communication device having at least one antenna that is configured to collect interference data relating to interference noise affecting communication signals being received by the communication device. The interference may include RF interference, such as AM radio interference, crosstalk and other types of interference from various sources. The interference data collected by the antenna is used by an interference canceller to remove and / or cancel some or all of the interference affecting received signals. In some embodiments of the present invention, more than one antenna may be used, wherein each antenna can collect interference data pertaining to a single source of interference noise. Where a modem or other communication device is coupled to multiple telephone lines, only one of which is being used as the active DSL line, wires in the remaining telephone lines or loops can be used as antennas. Moreover, the antenna may be an antenna, per se, such as a compact AM radio antenna or any other suitable structure or device for collecting the type(s) of interference affecting signals received by the communication device.

This invention describes a method for efficient beamforming for generalized sidelobe canceling using complementary noise separation filtering for generating a noise reference for adaptation performance of an adaptive interference canceller (AIC). The adaptive filter provides noise estimates to be subtracted from the desired signal path providing further noise reduction in the system output. More specifically, the present invention relates to a multi-microphone beamforming system similar to a generalized sidelobe canceller (GSC) structure, but the difference with the conventional GSC method is that the complementary filter used for desired signal blocking can be realized with a simple subtraction without compromising the beam steering flexibility of the polynomial beamforming filter front end using the desired target signal and the complementary background noise estimate signal, respectively, with the complexity of one complementary filter and one sum beamformer.

Provided are a receiver, a transmitter and a radio communication method capable of using non-orthogonal multiple access while suppressing cost increase and processing delay. A mobile station 200A includes a target user control signal detector 230 and an interfering user control signal detector 240 which are configured to receive a control signal to be used to cancel a non-orthogonal signal by interference canceller. The control signal includes control information containing a radio resource block allocated to the non-orthogonal signal addressed to another mobile station. The mobile station 200A demodulates and cancels the radio signal addressed to the other mobile station on the basis of the control signal.

Provided are a receiver, a transmitter and a radio communication method capable of using non-orthogonal multiple access while suppressing cost increase and processing delay. A mobile station 200A includes a physical channel segmentation unit 210 and data demodulating / decoding units 220. A radio resource block allocated to non-orthogonal signals is defined in a frequency domain, a time domain and a non-orthogonal multiplex domain. The non-orthogonal multiplex domain has multiple levels corresponding to the number of interference cancellations by the data demodulating / decoding units 220. Interference canceller of the mobile station 200A cancels a non-orthogonal signal whose allocated radio resource block is at a lower level than that of the mobile station 200A.

A method for increasing cellular system capacity includes receiving a signal in a time slot and a frequency band and transmitting a signal in the same time slot and the same frequency band. An adaptive self-interference canceller is used to reduce the radio frequency self-interference created by receiving and transmitting signals in the same time slot and the same frequency band. The self-interference can be further reduced by using: (1) a circulator connected between an antenna, a receiver, and a transmitter; (2) separate antennas for receiving and transmitting signals can be used; and / or (3) an adaptive antenna.

In a mobile communication system employing code division multiple accesses and having radio logical channels such as control channels and traffic channels, for the purpose of interference cancellation processing which is implemented without a large processing delay even under a call control application, the baseband receiving part of the mobile communication system includes a common control channel demodulator 302 which executes the demodulation processing of a common control channel as to a received baseband reception signal 301, an interference canceller 309 which executes interference cancellation processing for a received multiplexed signal on the basis of the notification information of the control channels, and a synthesis / error correction processor 315 which executes error correction processing, etc. as to user information having undergone the interference cancellation processing and thereafter executes frame formation processing. The common control channel is demodulated by the common control channel demodulator 302 and is not submitted to interference cancellation processing, thereby to heighten the processing speed of system information. In the interference canceller 309, cross-correlation interferences are cancelled as to the dedicated control channel and the traffic channel other than the common control channel, thereby to enhance a channel efficiency.

The present invention describes a method for temporal adjustment of adaptation control of an adaptive interference canceller (AIC) based on spatially weighted beamforming pre-processing. Most importantly, the present invention enhances the spatial blocking performance, while generating noise references for the AIC by a beamformer, by introducing dynamic adjustment to the AIC filter adaptation control. As a result, adaptation is effectively realized in two dimensions—spatial and temporal. The criterion for adjusting the AIC filter adaptation control is applied continuously following generation of the noise references. Essential in the invention is the comparison of the short-time powers or levels of the noise reference signals and desired signal beams and allowing the adaptation of the AIC filter under consideration only when the noise reference signal power is large enough in comparison with the desired signal power.

An adaptive interference cancellation receiving system uses synthesizer phase accumulation. A coupler coupled to a transmitter samples an undesired transmit signal. An adaptive interference canceller (AIC) module varies phase and amplitude of the sampled undesired transmit signal to provide a cancellation output signal. The AIC module has a frequency synthesizer with phase accumulation for varying the phase of the sampled undesired transmit signal. An antenna receives receive signals and the undesired transmit signal. A summing circuit connected to the receive antenna and the adaptive interference module sums the receive signals, the received undesired transmit signal, and the cancellation signal to cancel the received undesired transmit signal. An AIC controller module is coupled to the summing circuit output to detect a null in the undesired transmit signal, to generate a cancellation feedback signal, and to provide the cancellation feedback signal to the AIC module.

A DS-CDMA (Direct Sequence-Code Division Multiple Access) multi-user interference canceller cancels interference waves of a plurality of users. The DS-CDMA includes a variable gain controller for comparing reception characteristics of reception signals received from the plurality of users prior to interference cancellation processing with reception characteristics upon the interference cancellation processing and evaluating a comparison result, and controlling gains prior to baseband decoding of the reception signals so as to maximize improvements of the reception characteristics of the reception signals on the basis of an evaluation result. A CDMA multi-user system using the above canceller is also disclosed.

A full duplex wireless system is employed for communicating data between an access point and a client. The full duplex wireless system includes a receive path configured to receive radio frequency data, including self interference, from an antenna and generates baseband output to a demodulator, the receive path includes a combiner that combines the received radio frequency with a self interference canceller path output to generate a combiner output. Further, a self interference tracking path is configured to receive the combiner output and to generate a self interference tracking path output, the self interference tracking path converts the combiner output to baseband and tracks the self-interference. Additionally, a self interference canceller path receives the self interference tracking path output and generates the self interference canceller path output that is at radio frequency (RF).

A method and apparatus for using a multi-user detector for reducing multiple access interference (MAI) in a direct sequence CDMA wireless system such as W-CDMA. A superconducting rapid single flux quantum (RSFQ) RF digital receiver operating in combination with an RSFQ successive interference canceller (SIC) is located in the base stations of the wireless system. In the present invention, the RSFQ SIC is a vector machine capable of processing the cross-correlation matrices using an iterative method to decorrelate the user binary code sequences from the input signal in which the interference components are removed. According, the reduction in interference results in a significant increase in system capacity while improving cellular coverage area.

The invention discloses a multi-user wireless communication system based on both-way trunk and a method thereof; the communication system comprises four multi-antenna transceivers (not only a transmitter but also a receiver) and a multi-antenna both-way trunk; each transceiver is composed of an orthogonal frequency division multiplexing (OFDM) modulator, an OFDM demodulator, a memory and a self-interference eliminator; the both-way trunk is composed of an OFDM modulator, an OFDM demodulator and a beam former and is a semi-duplex amplifying transmission relay. The communication method leads a complete communication process to be finished within two time slots; in the first time slot, the four transceivers send signals to the relay at the same time, and an orthogonal frequency division multiple access is adopted as a multiple access way; in the second time slot, the relay adopts orthogonal frequency division multiplexing / space division multiplexing multiple access (OFDM / SDMA) as a multiple access way for leading received signals after being processed to be broadcasted to the four transceivers. In the invention, two multiple access ways are integrated, and relay beam forming matrixes suitable for different requirements of relay antenna number are respectively designed by adopting the two methods, thereby effectively utilizing space diversity to eliminate interference among the transceivers, and compared with the existing relay communication technology, the higher system and speed are realized.

A radio communication device for receiving a single-carrier signal transmitted in a partial spectrum of Nyquist frequency band, includes: an interference eliminator for eliminating interference from a received signal by spectrum reproduction of non-transmitted spectra using a symbol replica, to output an interference eliminated signal, wherein the interference includes intersymbol interference which is caused by symbols which are more than a predetermined distance away from a decision symbol point; a symbol sequence estimator for estimating a transmission symbol sequence by separating nearby intersymbol interference within the predetermined distance of the decision symbol point based on the interference eliminated signal, to output a decision signal; and a replica generator for generating the symbol replica from decoding result of the decision signal, wherein the symbol replica is fed back to the frequency-domain interference eliminator.

The present invention is directed to an interference canceller for a DS-CDMA communication system and a radio communication device that performs multi-rate transmission and eliminates interference of high-rate channels by a simplified structure. In a DS-CDMA communication system that performs a multi-rate transmission including at least low-rate channels and high-rate channels, there is provided an interference canceller that includes an array antenna interference replicating unit. The interference replicating unit is used in high-rate channels that receive signals received via array antenna elements and creates interference replicas of the high-rate channels. The system also includes an adder 6, which subtracts the interference replicas from the received signal via the array antenna elements. Further a resultant interference-eliminated signal is applied to receivers for the low-rate and high-rate channels.

An interference canceller between a transmit chain and a receive chain of a transceiver is proposed to complement the action of a diplexer, or duplex filter, that is part of the transceiver. The interference canceller comprises a transmit chain tap, a receive chain coupler for coupling an interference compensation signal into the receive chain, and an interference signal processing path between the transmit chain tap and the receive chain coupler. The interference signal processing path comprises a filter having filtering characteristics similar or corresponding to the filtering characteristic of a receive portion of said diplexer. A corresponding method for interference cancellation is also proposed. Computer-program products for the manufacture of the interference canceller and the execution of the method are also proposed.

An OFDMA-MIMO receiver performs a recursive interference cancellation across several correlated subbands and several receive antenna elements to demodulate complex source symbols for several users that have been coded across several subbands and transmit antennas. The iterative parallel interference canceller (PIC) is configured to work in the presence of both spatial and frequency structure introduced by the transmitter space-frequency mapping and the actual frequency selective wireless channel. The interference canceller uses mixed decisions, confidence weights, and stabilizing step sizes in a PIC receiver, which may be used with a successive decoding architecture in a receiver that employs a combination of modulation level interference cancellation with successive decoding.

A system that combines MIMO spatial multiplexing and dual polarization transmission is provided. The system is constructed with a simple circuit configuration, whereby a wireless communication system which accurately demodulates signals that are multiplexed doubly, both spatially and in polarization, is provided. The wireless communication system is a MIMO communication system that uses a plurality of antennas to form a plurality of fixed transmission channels, and includes a transmitting section and a receiving section. The transmitting section performs MIMO spatial multiplexing as well as dual polarization transmission of transmitting two independent signals in the same band by using two mutually orthogonal polarizations of radio waves as signals to be transmitted from respective antennas on a transmitting side. The receiving section includes an inference canceller and a MIMO signal processing circuit that is connected to the interference canceller. The interference canceller performs signal processing for eliminating an interference component between the polarizations by adaptive control on signals received by respective antennas on a receiving side. The MIMO signal processing circuit performs signal processing for MIMO spatial demultiplexing independent of the signal processing of the interference canceller.

A receiver employs low-rate processing to synthesize the effect of high-rate interference in a received multi-rate signal. Each high-rate subchannel is analyzed on its low-rate descendents to produce symbol estimates for each low-rate symbol interval. The symbol estimates are applied to low-rate descendent subchannels, which are then combined to synthesize the effects of the high-rate interference. An interference canceller processes the synthesized interference with the received signal for producing an interference-cancelled signal. Alternatively, analogous steps may be applied at high-rate to analyze, synthesize, and cancel the effects of low-rate interference in a multi-rate signal.

Different carrier frequencies are chosen for plural transmitters of a transmitting device and signals are transmitted at frequency bands overlapping each other. In the receiving device weighting coefficients are provided in input-to-output paths of an interchannel interference canceller 21 so that the cross correlation between output signals from the interchannel interference canceller is minimized.

The purpose of the present invention is to offer a structure of a CDMA system having a power control method and interference cancellers which can effectively increase the system capacity and is resistant to sudden changes on the communication path, and to achieve a power control method with a fast response capable of preventing unnecessary increases in the transmission power (and multiple access interference) of the uplink by reflecting the values of the post-interference cancellation signal-to-interference power ratio in the generation of power control command information. The invention is directed to a power control method in a communication system for performing communications by code-division multiple access between a mobile station and base station, wherein a multiple access interference signal contained in a reception signal from the mobile station is cancelled, a post-interference cancellation signal-to-interference power ratio of the reception signal currently received is estimated, a power control command is generated by comparing the estimated post-interference cancellation signal-to-interference power ratio and a target value for power control, and transmitting this power control command to the mobile station to control the transmission power of the mobile station.

A communication apparatus capable of echo cancellation is provided. The apparatus is configured to be provided with an input signal receiving interference. The input signal has a frequency range. The interference includes an echo component and a noise component. The apparatus has a first interference eliminator configured to reduce an echo component included in the input signal so as to produce an intermediate signal. The apparatus has a selector configured to select one of the input signal and the intermediate signal. The apparatus has a second interference eliminator configured to reduce at least one of a noise component and an echo component included in one of the input signal and the intermediate signal selected by the selector.

A multi-path signal interference cancellation system cancels multiple time delayed signal components of a multi-path interference signal received by a receive antenna and carried on a receiver transmission line of a radio receiver system. The interference cancellation system includes a plurality of adaptive interference canceller circuits, each of which has a synchronous detector, a signal controller and an integrator as essential parts of closed control loops defined by the canceller circuits. The integrator has gain and bandwidth characteristics associated therewith which are adjustable to adjust the gain and bandwidth of each closed control loop. An intensity profile of the multi-path interference signal is generated and stored in a memory. An intensity profile signal from the memory is provided to the integrator of each adaptive interference canceller circuit to adjust the gain and bandwidth of the integrator and the loop in which it is situated to maximize the error detection residual signal-to-noise ratio of each adaptive interference canceller circuit. Each adaptive interference canceller circuit generates a cancellation signal from which a synthesized cancellation signal is generated and effectively injected onto the receiver transmission line to cancel the multiple time delayed signal components of the multi-path interference signal carried thereon so that the radio receiver of the radio receiver system only receives a desired signal.