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2869 results about "Precoding" patented technology

Precoding is a generalization of beamforming to support multi-stream (or multi-layer) transmission in multi-antenna wireless communications. In conventional single-stream beamforming, the same signal is emitted from each of the transmit antennas with appropriate weighting (phase and gain) such that the signal power is maximized at the receiver output. When the receiver has multiple antennas, single-stream beamforming cannot simultaneously maximize the signal level at all of the receive antennas. In order to maximize the throughput in multiple receive antenna systems, multi-stream transmission is generally required.

System and method for DIDO precoding interpolation in multicarrier systems

A system and machine-implemented method are described for performing precoding interpolation in a DIDO system which employs orthogonal frequency-division multiplexing (OFDM) and DIDO precoding to communicate with a plurality of distributed-input-distributed-output (DIDO) clients. For example, a system according to one embodiment of the invention comprises: selecting a first subset of ODFM tones to determine a first subset of precoding weights; deriving a second subset of precoding weights for a second subset of ODFM tones by interpolating between the first subset of precoding weights; and using a combination of the first subset of precoding weights and the second subset of precoding weights to precode a data stream prior to transmitting the data stream to a DIDO client.
Owner:REARDEN

System and method for distributed input distributed output wireless communications

A system and method are described for compensating for frequency and phase offsets in a multiple antenna system (MAS) with multi-user (MU) transmissions (“MU-MAS”). For example, a method according to one embodiment of the invention comprises: transmitting a training signal from each antenna of a base station to one or each of a plurality of wireless client devices, one or each of the client devices analyzing each training signal to generate frequency offset compensation data, and receiving the frequency offset compensation data at the base station; computing MU-MAS precoder weights based on the frequency offset compensation data to pre-cancel the frequency offset at the transmitter; precoding training signal using the MU-MAS precoder weights to generate precoded training signals for each antenna of the base station; transmitting the precoded training signal from each antenna of a base station to each of a plurality of wireless client devices, each of the client devices analyzing each training signal to generate channel characterization data, and receiving the channel characterization data at the base station; computing a plurality of MU-MAS precoder weights based on the channel characterization data, the MU-MAS precoder weights calculated to pre-cancel frequency and phase offset and / or inter-user interference; precoding data using the MU-MAS precoder weights to generate precoded data signals for each antenna of the base station; and transmitting the precoded data signals through each antenna of the base station to each respective client device.
Owner:REARDEN LLC

MIMO precoding enabling spatial multiplexing, power allocation and adaptive modulation and coding

In a closed-loop wireless communication system, a codebook-based feedback mechanism is provided to enable non-unitary precoding for multi-stream transmission, where in each stream is optimized with suitable transmission power allocation and AMC. The codebook-based feedback mechanism uses a precoding codebook having a power allocation matrix which is constrained to specify that beamforming always applies full power to a predetermined beam. With this constraint, a one-bit power allocation feedback index may be used to switch between beamforming and spatial multiplexing.
Owner:APPLE INC

Apparatus and method for scheduling resource in a multiuser MIMO radio communication system

In a multiuser Multiple Input Multiple Output (MIMO) radio communication system, a transmitter receives channel quality information transmitted from receivers, schedules resource for the receivers within a corresponding scheduling epoch based on the received channel quality information. Thereafter, the transmitter pre-codes signals to be transmitted to the resource-scheduled receivers in a predetermined coding method before transmission, thereby maximizing system transmission efficiency.
Owner:SAMSUNG ELECTRONICS CO LTD +1

Method and apparatus for providing closed-loop transmit precoding

A method for providing closed-loop transmit precoding between a transmitter and a receiver, includes defining a codebook that includes a set of unitary rotation matrices. The receiver determines which preceding rotation matrix from the codebook should be used for each sub-carrier that has been received. The receiver sends an index to the transmitter, where the transmitter reconstructs the precoding rotation matrix using the index, and precodes the symbols to be transmitted using the preceding rotation matrix. An apparatus that employs this closed-loop technique is also described.
Owner:TEXAS INSTR INC

Method and apparatus of transmitting reference signal for uplink transmission

A method and apparatus of transmitting a reference signal in a wireless communication system is provided. The method includes generating a precoded reference signal or a non-precoded reference signal in accordance with a rank, and transmitting the generated reference signal. Uplink transmission using multiple transmit antennas is supported through reference signal design and related control signaling.
Owner:LG ELECTRONICS INC

Pre-coder selection based on resource block grouping

The present invention provides a receiver. In one embodiment, the receiver includes a receive portion employing transmission signals from a transmitter having multiple antennas and capable of providing channel estimates. The receiver also includes a feedback generator portion configured to provide to the transmitter a pre-coder selection for data transmission that is based on the channel estimates, wherein the pre-coder selection corresponds to a grouping of frequency-domain resource blocks. The present invention also provides a transmitter having multiple antennas. In one embodiment, the transmitter includes a transmit portion coupled to the multiple antennas and capable of applying pre-coding to a data transmission for a receiver. The transmitter also includes a feedback decoding portion configured to decode a pre-coder selection for the data transmission that is fed back from the receiver, wherein the pre-coder selection corresponds to a grouping of frequency-domain resource blocks.
Owner:TEXAS INSTR INC

Interference management, handoff, power control and link adaptation in distributed-input distributed-output (DIDO) communication systems

A system and method are described herein employing a plurality of distributed transmitting antennas to create locations in space with zero RF energy. In one embodiment, when M transmit antennas are employed, it is possible to create up to (M−1) points of zero RF energy in predefined locations. In one embodiment of the invention, the points of zero RF energy are wireless devices and the transmit antennas are aware of the channel state information (CSI) between the transmitters and the receivers. In one embodiment, the CSI is computed at the receivers and fed back to the transmitters. In another embodiment, the CSI is computed at the transmitter via training from the receivers, assuming channel reciprocity is exploited. The transmitters may utilize the CSI to determine the interfering signals to be simultaneously transmitted. In one embodiment, block diagonalization (BD) precoding is employed at the transmit antennas to generate points of zero RF energy.
Owner:REARDEN

MIMO precoding in the presence of co-channel interference

Methods and systems for communicating in a wireless network include mitigating co-channel interference (CCI) for precoded multiple-input multiple-output (MIMO) systems and incorporating the effect of CCI mitigation on channel characteristics in the design of channel state information (CSI) feedback mechanisms. Various embodiments and variants are also disclosed.
Owner:INTEL CORP

Adaptive multi-user MIMO non-cooperative threshold-based wireless communication system using limited channel feedback

A system and methodology for efficient multi-user transmission in a wireless communication with limited feedback are provided. A non-cooperative feedback-based multi-user transmission scheme is described, wherein users in a wireless communication system may independently communicate selected channel information feedback to the base station. The base station may then choose suitable precoding weights based on the received channel information feedback. An adaptive threshold-based feedback approach is also described for multi-user transmission, wherein the quality of feedback for each user can be quantified by a special threshold by the system prior to engaging in multi-user communication.
Owner:YIM TU INVESTMENTS

System and method for distributed input distributed output wireless communications

A system and method are described for compensating for frequency and phase offsets in a multiple antenna system (MAS) with multi-user (MU) transmissions (“MU-MAS”). For example, a method according to one embodiment of the invention comprises: transmitting a training signal from each antenna of a base station to one or each of a plurality of wireless client devices, one or each of the client devices analyzing each training signal to generate frequency offset compensation data, and receiving the frequency offset compensation data at the base station; computing MU-MAS precoder weights based on the frequency offset compensation data to pre-cancel the frequency offset at the transmitter; precoding training signal using the MU-MAS precoder weights to generate precoded training signals for each antenna of the base station; transmitting the precoded training signal from each antenna of a base station to each of a plurality of wireless client devices, each of the client devices analyzing each training signal to generate channel characterization data, and receiving the channel characterization data at the base station; computing a plurality of MU-MAS precoder weights based on the channel characterization data, the MU-MAS precoder weights calculated to pre-cancel frequency and phase offset and / or inter-user interference; precoding data using the MU-MAS precoder weights to generate precoded data signals for each antenna of the base station; and transmitting the precoded data signals through each antenna of the base station to each respective client device.
Owner:REARDEN

Method and apparatus for adaptively compensating channel or system variations in precoded communications system

The present invention relates to a method and apparatus for adaptively compensating for channel or system variations in which adaptive compensation is used in the receiver of a digital communication system. The transmitter of the digital communication system includes precoding. The adaptive receiver compensation mitigates the interferences not removed by the transmitter precoder. In an embodiment of the invention, the adaptive compensation can be performed using an adaptive feedforward filter (FFF) and a feedback filter (FBF) in the receiver. The FBF output is generated based on previous values of estimates of the transmitted precoded sequence. The determined value of the FBF coefficients can be periodically relayed to the transmitter to update the precoder coefficients of the transmitter. Alternatively, the value of the FBF coefficients can be relayed to the transmitter after the value of the coefficients exceeds a predetermined threshold. Accordingly, the receiver adaptively and automatically compensates for misadjustments of the fixed transmitter precoder with respect to the actual channel at a given point in time.
Owner:THE TRUSTEES FOR PRINCETON UNIV

Feedback reduction for MIMO precoded system by exploiting channel correlation

In a closed-loop wireless communication system, a codebook-based precoding feedback compression mechanism is provided to remove redundancy from the precoding feedback that is caused by channel correlation in time and frequency. Redundancy due to temporal correlation of the transmission channel is removed by sending precoding feedback only if there is a change in the precoder state for the channel to the receiver. Redundancy due to frequency correlation is removed by run length encoding the precoding feedback, thereby compressing the precoding feedback prior in the frequency domain. By compressing the precoding feedback, the average rate of precoder feedback is reduced.
Owner:NXP USA INC

Precoded OFDM systems robust to spectral null channels and vector OFDM systems with reduced cyclic prefix length

A precoded orthogonal frequency division multiplexer (OFDM) system that improves the preformance of OFDM systems for spectral null channels, and size K×1 vector OFDM systems that reduce the cyclic prefix length by K times compared to conventional OFDM systems. The precoding scheme comprises inserting one or more zeros between each of the two sets of K consecutive information symbols, although it can be generalized to a general form. This precoding scheme removes the spectral nulls of an ISI channel without knowing the ISI channel. When no zero is inserts between each of the two sets of K consecutive information symbols and only K consecutive symbols are blocked together, vector OFDM systems are obtained. The bit error rate performance of the vector OFDM systems of the present invention is much improved over conventional OFDM systems.
Owner:UNIVERSITY OF DELAWARE

System and Method For Distributed Input-Distributed Output Wireless Communications

A system and method are described for dynamically adapting the communication characteristics of a multiple antenna system (MAS) with multi-user (MU) transmissions (“MU-MAS”). For example, a method according to one embodiment of the invention comprises: transmitting a training signal from each antenna of a base station to each of a plurality of wireless client devices, each of the client devices analyzing each training signal to generate channel characterization data, and receiving the channel characterization data at the base station; computing a plurality of MU-MAS precoder weights based on the channel characterization data, the combined MU-MAS precoder weights comprising a MU-MAS channel matrix; determining instantaneous or statistical channel quality (“link quality metric”) for the wireless client devices using mutual information of MU-MAS links or singular values of the MU-MAS composite channel matrix; determining a subset of users and a MU-MAS transmission mode based on the link quality metric; precoding data using the MU-MAS precoder weights to generate precoded data signals for each antenna of the base station; and transmitting the precoded data signals through each antenna of the base station to each respective client device within the selected subset.
Owner:REARDEN

MIMO wireless precoding system robust to power imbalance

InactiveUS20080303699A1Sacrificing scheduling flexibilityAvoid power imbalanceComputation using non-contact making devicesCode conversionPrecodingUser equipment
The present invention relates to methods and apparatus for preventing power imbalance in a multiple input multiple output (MIMO) wireless precoding system. According to one aspect of the present invention, a codebook is constructed with a first subset of codewords that are constant modulus matrices, and a second subset of codewords that are non-constant modulus matrices. A mapping scheme is established between the first subset of codewords and the second subset of codewords. When a unit of user equipment feeds back a first codeword that is a non-constant modulus matrix, the Node-B may replace the first codewords with a second codeword that is selected from the first subset of codewords and that corresponds to the first codeword in accordance with the mapping scheme.
Owner:SAMSUNG ELECTRONICS CO LTD

Coding of a syntax element contained in a pre-coded video signal

A method for encoding a syntax element contained in a precoded video signal into a coded bit stream, the precoded video signal representing at least one video frame, the syntax element being associated with a predetermined portion of the video frame and being indicative of as to whether the predetermined portion of the video frame is precoded in a first or a second way into the precoded video signal is described. The method comprises investigating as to whether a neighboring portion of the video frame neighboring the predetermined portion is precoded in the first way or the second way, in order to obtain a binary value; assigning one of at least two context models to the predetermined portion of the video frame based on the binary value, wherein each context model is associated with a different probability estimation; and arithmetically encoding the syntax element into the coded bit stream based on the probability estimation with which the assigned context model is associated.
Owner:FRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG EV

System and method for distributed input-distributed output wireless communications

A system for compensating for in-phase and quadrature (I / Q) imbalances for multiple antenna systems (MAS) with multi-user (MU) transmissions (defined with the acronym MU-MAS), such as distributed-input distributed-output (DIDO) communication systems, comprising multicarrier modulation, such as orthogonal frequency division multiplexing (OFDM). For example, one embodiment of the system comprises one or more coding modulation units to encode and modulate information bits for each of a plurality of wireless client devices to produce encoded and modulated information bits; one or more mapping units to map the encoded and modulated information bits to complex symbols; and a MU-MAS or DIDO IQ-aware precoding unit to exploit channel state information obtained through feedback from the wireless client devices to compute MU-MAS or DIDO IQ-aware precoding weights, the MU-MAS or DIDO IQ-aware preceding unit precoding the complex symbols obtained from the mapping units using the weights to pre-cancel interference due to I / Q gain and phase imbalances and / or inter-user interference.
Owner:REARDEN

System and method for transmitting signals in cooperative base station multi-user MIMO networks

A method transmits and receives signals in a cooperative, multi-user, multi-input, multi-output network. The network includes base stations (BSs) and mobile stations (MSs). Each BS has at least two antennas, and each MS has at least one antenna. At a first base station and a second base station using linear pre-coding matrices, a plurality of data streams are jointly pre-coded to produce first signals and second signals. The first signals are transmitted synchronously from the first BS and the second BS to a first MS, and the second signals are transmitted synchronously from the first BS and the second BS to a second MS, and in the first signal and the second signal are asynchronous with respect each other.
Owner:MITSUBISHI ELECTRIC RES LAB INC

Method and apparatus for transmitting/receiving csi-rs in massive MIMO system operating in fdd mode

Methods and apparatus are provided for beamforming and information feedback are provided. Signals for beams to be transmitted through corresponding antenna ports, are generated. The beams are formed by precoding the signals with beamforming vectors. The beams are sorted into a number of resource reuse groups based on a resource that is to be shared. The beams are transmitted, using resources allocated per group, to a receiver. Feedback information is generated on at least one antenna port, based on the received beams. The feedback information is transmitted to the transmitter. A beam is selected having a greatest gain for a transmitter using the feedback information. A transmission resource is allocated for the selected beam.
Owner:SAMSUNG ELECTRONICS CO LTD +1

Reduced complexity transmit spatial waterpouring technique for multiple-input, multiple-output communication systems

A waterpouring system and method for use with a multiple-input, multiple-output (MIMO) transmitter. In one embodiment, the waterpouring system includes an encoding decision subsystem that selects a constellation combination based on gains in channels of the MIMO transmitter, and a vector modulator subsystem, coupled to the encoding decision system, that modulates a fixed number of bits in a bitstream with the constellation combination to generate a symbol vector. The waterpouring system also includes a normalization and precoding subsystem, coupled to the vector modulator subsystem, that weights the symbol vector based on the gains to yield a weighted symbol vector and distributes the weighted symbol vector among the channels.
Owner:TEXAS INSTR INC

System and method for distributed input-distributed output wireless communications

A system for compensating for in-phase and quadrature (I / Q) imbalances for multiple antenna systems (MAS) with multi-user (MU) transmissions (defined with the acronym MU-MAS), such as distributed-input distributed-output (DIDO) communication systems, comprising multicarrier modulation, such as orthogonal frequency division multiplexing (OFDM). For example, one embodiment of the system comprises one or more coding modulation units to encode and modulate information bits for each of a plurality of wireless client devices to produce encoded and modulated information bits; one or more mapping units to map the encoded and modulated information bits to complex symbols; and a MU-MAS or DIDO IQ-aware precoding unit to exploit channel state information obtained through feedback from the wireless client devices to compute MU-MAS or DIDO IQ-aware precoding weights, the MU-MAS or DIDO IQ-aware preceding unit precoding the complex symbols obtained from the mapping units using the weights to pre-cancel interference due to I / Q gain and phase imbalances and / or inter-user interference.
Owner:REARDEN

Efficient MIMO precoding feedback scheme

ActiveUS20090080549A1Efficiently feeding back precodingTransmission path divisionCriteria allocationPrecodingTheoretical computer science
Methods and apparatus for efficiently feeding back preceding information in a multiple input multiple output (MIMO) system. A codebook including a plurality of codebook entries is constructed. A plurality of subsets of codebook entries are defined for the codebook. Each subset includes a plurality of codebook entries. A subset of codebook entries is selected for precoding data in dependence upon a channel condition, and a codebook entry is selected from the subset. Then, a subset index corresponding to the selected subset, and a codebook entry index corresponding to the selected codebook entry within the selected subset, is transmitted as feedback information.
Owner:SAMSUNG ELECTRONICS CO LTD

Methods and apparatus for centralized and coordinated interference mitigation in a WLAN network

Method and apparatus for interference mitigation in wireless local area networks (such as WLANs). In one embodiment, a centralized interference measurement and mitigation method is disclosed. The method may involve spectral sensing, beamforming, MIMO, power control, MAC scheduling using a cross-layer approach, and / or broadcast channel precoding, employed towards performance enhancement of WLAN networks in presence of interference. In one variant, different actions at interference mitigation are selected based on the source of the interference (e.g., inter-network or intra-network).
Owner:SAFAVI SAEID

System and method for spatial-multiplexed tropospheric scatter communications

A method is described comprising: transmitting a training signal from each antenna of a base station to each of a plurality of client devices utilizing tropospheric scatter, each of the client devices analyzing each training signal to generate channel characterization data, and transmitting the channel characterization data back to the base station utilizing tropospheric scatter; storing the channel characterization data for each of the plurality of client devices; receiving data to be transmitted to each of the client devices; and precoding the data using the channel characterization data associated with each respective client device to generate precoded data signals for each antenna of the base station; and transmitting the precoded data signals through each antenna of the base station to each respective client device.
Owner:REARDEN
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