375 results about "Mimo channel" patented technology

Methods and apparatus are provided for communicating data in a multiple antenna communication system having N transmit antennas. According to one aspect of the invention, a header format includes a legacy preamble having at least one legacy long training field and an extended portion having at least N additional long training fields on each of the N transmit antennas. The N additional long training fields may be tone interleaved across the N transmit antennas and are used for MIMO channel estimation. The extended portion may include a short training field for power estimation. The short training field may be tone interleaved across the N transmit antennas and have an extended duration to support beam steering.

Frequency-independent eigensteering in MISO and MIMO systems are described. For principal mode and multi-mode eigensteering, a correlation matrix is computed for a MIMO channel based on channel response matrices and decomposed to obtain N_S frequency-independent steering vectors for N_S spatial channels of the MIMO channel. ND data symbol streams are transmitted on N_D best spatial channels using N_D steering vectors, where N_D=1 for principal mode eigensteering and N_D>1 for multi-mode eigensteering. For main path eigensteering, a data symbol stream is transmitted on the best spatial channel for the main propagation path (e.g., with the highest energy) of the MIMO channel. For receiver eigensteering, a data symbol stream is steered toward a receive antenna based on a steering vector obtained for that receive antenna. For all eigensteering schemes, a matched filter is derived for each receive antenna based on the steering vector(s) and channel response vectors for the receive antenna.

A distributed antenna system includes a master unit configured to receive at least one set of multiple input multiple output (MIMO) channel signals from at least one signal source. The master unit is configured to frequency convert at least one of the MIMO channel signals to a different frequency from an original frequency, and combine the MIMO channel signals for transmission. An optical link couples the master unit with a remote for transceiving the MIMO channel signals. The remote unit is configured to receive the MIMO channel signals to be transmitted over antennas and includes an extension port configured to transceive at least one of the MIMO channel signals. An extension unit is coupled to the remote unit and is configured to frequency convert at least one of the first and second MIMO channel signals from the different frequency back to an original frequency for transmission over an antenna.

An innovative testing apparatus and method for a multi-paths simulating system is proposed. The testing apparatus comprises a shielded chamber to avoid the external electromagnetic interference and other unexpected transmission paths. The multi-paths simulating system is utilized by attenuators for simulating a communication effects in a MIMO channel propagation environment. A control unit can set of MIMO and SISO modes of TD, RD and DUT to determine attenuation difference and downlink, uplink throughputs difference of the TD, RD and DUT.

A method for estimating a communication channel comprising one or more sub-channels between at least a first transceiver and at least a second transceiver is provided. The method comprises transmitting a first set of training data from the first transceiver to the second transceiver, receiving observed signals at the second transceiver, re-transmitting said observed signal back to the first transceiver, and calculating a roundtrip channel estimate at the first transceiver. The method further comprises transmitting a second set of training data from the second transceiver to the first transceiver, receiving observed signals at the first transceiver, and calculating a reverse link channel estimate. From the roundtrip channel estimate and the reverse link channel estimate, a forward link channel estimate is computed at the first transceiver.

Systems and methods for receiving MIMO signals for testing and analyzing operation of MIMO communications devices. Examples of systems and/or methods for receiving MIMO signals include a measuring receiver with N RF paths consisting of N downconverters. Each downconverter achieves a frequency shift of the input MIMO signal equal to a shifting frequency of a first intermediate frequency (IF) plus a delta determined by the signal bandwidth multiplied by an integer number between 1 and N. The shifted N MIMO signals are combined to generate one combined analog MIMO signal. An analog to digital converter converts the combined analog MIMO signal to a stream of digital samples where the samples may be tested and analyzed with metrics on signals communicated in a MIMO environment. Example systems and method for receiving MIMO signals may also be implemented as a MIMO channel emulator such that samples generated by the ADC may be upconverted to output copies of the original signals to a receiver DUT, for example.

Communication operation is performed with enhanced transmission efficiency by obtaining enhanced communication capacity through optimal allocation of transmission powers to individual MIMO channels obtainable by spatial multiplexing. A transmitter has a plurality of transmission antennas and a receiver has a plurality of reception antennas and perform spatial multiplex communication through transmission and reception with individual antenna weights being set. The transmitter varies the power allocation in units of a communication channel in correspondence to communication quality of the channel. The receiver uses a power allocation value of each communication channel that is estimated in accordance with a reception power of a pilot carrier included in user data after spatially separated. Thereby, the receiver returns the magnitude of the amplitude of a received signal in the signal spacing to an original magnitude, and performs an accurate demapping process.

Using at least one MIMO-capable transceiver allows weighting calculations for signals transmitted and received, and enables individual packets to adapt, in a scalable, flexible, and responsive fashion to the real-world dynamics of a continuously varying communications network environment. The method and system of this invention use adaptively-derived diversity means to rapidly and efficiently distinguish the desired signal from noise, network interference, and external interference impinging on the network's transceivers and can transmit with lessened overhead. ADC operations and signal transformations continuously update combiner weights to match dynamically-varying environmental and traffic conditions, thereby continuously matching necessitated signal and waveform transformations with environmental and signal effects and sources. Successive iterations of the adaptation algorithm let each node's multiport combiner and distribution weights approach the MIMO channel's Shannon capacity in high-rate networks, or to minimize power needed to close links at a specified rate in low-rate networks, e.g. Voice-Over-IP networks.

Methods and apparatuses for decoding codewords received over a MIMO channel are provided. According to one aspect of the disclosure, a cost function is computed for each constellation point of an Mth rank or spatial layer, and N_cand of those constellation points having minimum cost are preserved as candidate points, where N_cand is a parameter specified to the decoding algorithm. In addition, a cost function may be computed for all possible transitions from the N_cand candidate points of the Mth rank to all possible constellation points of the (M-1)th spatial layer, and N_cand of those transitions having minimum cost are preserved as candidate points. The process is repeated for all spatial layers, resulting in the identification of N_cand candidate codewords and their associated cost functions.

Dedicated pilot signals are transmitted from a transmitting device to a receiving device through a multicarrier MIMO channel in addition to data signals and common pilot signals. The dedicated pilot signals may be used by the receiving device to validate whether a predetermined beamforming matrix (i.e., a beamforming matrix identified by the receiving device) was used by the transmitting device to precode the transmitted data. If a different beamforming matrix was used for the preceding, the receiving device may use this matrix to demodulate the received data.

A system for transmitting data over a MIMO channel has a transmitter and a receiver. In the transmitter, the input data is encoded over at least two pipes by a concatenation of at least two constituent signal-space encoders. Each constituent encoder is used to generate, in response to the input data, a sequence of symbols from a channel alphabet having at least one dimension. Each symbol of the channel alphabet includes at least one complex symbol having real and imaginary coordinates. The transmitter interleaves the coordinates of the sequence of channel alphabet symbols, and transmits (from at least two transmit antennas) the interleaved coordinates. Preferably, each constituent encoder maximizes a minimum coordinate-wise Hamming distance between members of all valid pairs of symbol sequences, maximizes a minimum Euclidean distance between members of all valid pairs of different codewords, and obeys an equal eigenvalue criterion.

Techniques for deriving eigenvectors based on steered reference and used for spatial processing. A steered reference is a pilot transmission on one eigenmode of a MIMO channel per symbol period using a steering vector for that eigenmode. The steered reference is used to estimate both a matrix Σ of singular values and a matrix U of left eigenvectors of a channel response matrix H. A matrix Ũ with orthogonalized columns may be derived based on the estimates of Σ and U, e.g., using QR factorization, minimum square error computation, or polar decomposition. The estimates of Σ and U (or the estimate of Σ and the matrix Ũ) may be used for matched filtering of data transmission received via a first link. The estimate of U or the matrix Ũ may also be used for spatial processing of data transmission on a second link (for reciprocal first and second links).

A multi-input-multi-output (MIMO) communications system is provided for conveying signals over a MIMO channel. The system includes a precoder for precoding a signal based upon a uniform channel decomposition scheme. The system further comprises a transmitter in communication with the precoder for conveying the precoded signal over a subchannel of the MIMO channel.

A post-quantum physical-layer encryption/decryption system based on chaotic Baseband Modulation Hopping (BMH). The baseband constellation, mapping, power level, and phase will vary symbol-by-symbol according to assigned random sequences. Pre-shared secret keys are used as the chaotic system parameters, initialization, and quantization parameters to generate the BMH codes. The BMH physical-layer encryption/decryption system can be combined with digital-domain based encryption algorithms such as AES, code-based post-quantum cryptography, and other physical-layer secure communication techniques such as Frequency Hopping (FH) and Direct Sequence Spread Spectrum (DSSS). It can also be combined with Quantum Key Distribution (QKD) to provide mutual authenticated key distribution. This invention can be applied to all kinds of communication systems including wireless (radio frequency, optical, quantum channel, sonar) and wire (optical fiber, power-line, telephone line, wire quantum channel, etc.), single carrier and multi-carrier, OFDM, MIMO channels.

The invention discloses a large-scale MIMO channel state information feedback method based on deep learning. The method comprises the following steps: firstly, carrying out two-dimensional discrete Fourier transform (DFT) on a channel matrix H-wave of MIMO channel state information in a spatial frequency domain on a user side, so that a channel matrix H which is sparse in an angle delay domain isobtained; secondly, constructing a model CsiNet comprising a coder and a decoder, wherein the coder belongs to the user side and is used for coding the channel matrix H into codons with a lower dimension, and the decoder belongs to a base station side and is used for reconstructing an original channel matrix estimation value H-arrow from the codons; thirdly, training the model CsiNet to obtain model parameters; fourthly, carrying out two-dimensional inverse DFT on a reconstructed channel matrix H-arrow which is output by the CsiNet, so that a reconstructed value of the original channel matrixH-wave in the spatial frequency domain is recovered; and finally, using the trained model CsiNet for compressed sensing and reconstruction of channel information. The method provided by the inventionhas the advantages that large-scale MIMO channel state information feedback expenditures can be reduced, and an extremely high channel reconstruction quality and an extremely high channel reconstruction speed can be achieved.

The invention discloses a large-scale MIMO channel state information feedback method based on FCFNN, and mainly aims to solve the problems of overlarge technical feedback overhead and poor channel feedback quality in the prior art. According to the scheme, the method comprises the following steps: on a user side, performing two-dimensional discrete Fourier transform and truncation processing on adownlink channel matrix of a space-frequency domain to obtain a channel matrix H; building a channel feedback model including an encoder and a decoder, and training the channel feedback model; placingthe trained encoder and decoder on the user side and a base station side respectively; inputting the channel matrix H into the encoder to obtain a compressed vector h on the user side, and feeding back the compressed vector to a base station; inputting the h into the decoder to obtain a rebuilt channel matrix by the base station; and performing zero-padding and two-dimension inverse discrete Fourier transform on the rebuilt channel matrix to obtain an original space-frequency domain channel matrix. Through adoption of the large-scale MIMO channel state information feedback method, feedback overhead of the channel state information is lowered, and the channel rebuilding quality is improved remarkably. The large-scale MIMO channel state information feedback method can be applied to a large-scale multi-input and multi-output communication system under a frequency division duplex mode.

A method and system for frame formats for MIMO channel measurement exchange is provided. Aspects of a method for communicating information in a communication system may comprise transmitting data via a plurality of radio frequency (RF) channels utilizing a plurality of transmitting antenna, receiving feedback information via at least one of a plurality of RF channels, and modifying a transmission mode based on the feedback information. Aspects of a method for communicating information in a communication system may also comprise receiving data via a plurality of receiving antenna, transmitting feedback information via at least one of the plurality of RF channels, and requesting modification of a transmission mode for the received data in transmitted response messages comprising the feedback information.

Multiple wireless user devices act cooperatively to communicate with a remote destination node through a MIMO channel. In at least one embodiment, a cooperative cluster of user devices is formed that makes use of vertical coding techniques to achieve enhanced communication performance.

In a multiple-input multiple output (MIMO) system, high-rate data transmission is achieved by dividing the original data stream into several parallel data substreams, each of which is transmitted from a corresponding transmit antenna (spatial multiplexing) and received by multiple receive antennas. The number of spatial streams depends on the number of antennas. In a receiver, a search-tree based QR Decomposition-M (QRD-M) algorithm is used. According to the invention, multiple spatial signal streams received from a MIMO channel are pre-ordered based on modulation alphabets of said received spatial signal streams prior to performing a QRD-M detection.

A system, method and apparatus, provide for the utilization of the MIMO technique with single-antenna communication devices that maximize high-speed broadband communication. The apparatus includes a wireless communication interface (WCI) device configured to exchange wireless signals with a base station through a multiple input multiple output (MIMO) air interface and to exchange a corresponding set of wireless signals with an access terminal through a wideband air interface having a greater bandwidth than the bandwidth of the MIMO air interface. The system includes a plurality of WCI devices communicating with the base station and exchanging corresponding signals with the access terminal.

In a collaborative, multiple input, multiple output wireless communication system, a transmitting device transmits a peak-limited pilot signal to a receiving device. The receiving device independently synthesizes the same pilot signal transmitted by the transmitting device. The synthesis process involves precoding the pilot signal and peak limiting the precoded pilot signal. The receiving device receives a signal r that represents the product of (i) a channel matrix H between the transmitting device and the receiving device and (ii) the peak-limited pilot signal y_p(n)′ plus noise η, i.e. r=Hy_p(n)′+η. The synthesized, peak-limited pilot signal can then be used by a channel estimator to determine an estimated channel matrix Ĥ. Thus, the estimated channel matrix Ĥ represents a closer estimate of the channel matrix H than conventional channel estimation processes and, thus, can provide better corresponding performance than conventional MIMO wireless communication systems.

A technique to determine carrier frequency offset (CFO) phase shift and perform channel estimation for symbols of a signal communicated across a multiple-input-multiple-output (MIMO) communication channel, in which preambles utilized for channel estimation are sent over more than one time block. Because the transmission of preambles used for channel estimation are sent over multiple time blocks, a CFO phase shift that is flat across tones of an OFDM signal is experienced between preambles of the two time blocks. Upon detection of the CFO phase shift, a weighting matrix used for channel estimation is modified to account for the CFO phase shift, in order to perform the channel estimation with correction for the CFO phase shift.