Introduced here is at least one technique to better estimate interference at a receiver. The technique includes receiving a plurality of reference signals, which each have information indicative of noise. Thus, the technique further includes, for each reference signal, determining a noise estimation and determining a distance metric and log-likelihood ratio (LLR) of the noise estimation. Once the distance metric and LLR of each reference signal is determined, the receiver can determine a final LLR based on the distance metric and LLR of each reference signal. In this manner, a final LLR is determined. This technique can be applied by any device operating on MIMO technology.

A MIMO symbol detection and search method, a decoding circuit and a receiving antenna system are provided. The signal detection and search method includes the following steps. A symbol search tree is obtained, and a plurality of candidate symbols at each layer of the symbol search tree are sorted. The candidate symbols are traversed in sequence at each layer of the symbol search tree. At each layer of the symbol search tree, if a cumulative partial Euclidean distance is greater than or equal to a threshold, un-scanned candidate symbols are excluded. If the cumulative partial Euclidean distance is less than the threshold, the threshold is updated by the cumulative partial Euclidean distance. When all of the candidate symbols have been calculated, an estimated symbol combination is outputted, and the scan of the symbol search tree is terminated.

This disclosure provides methods, devices and systems for determining unavailable spatial streams in uplink multiuser (MU) multiple-in multiple-out (MIMO) communication. In one example, a device transmits, to wireless stations including a first wireless station, a trigger frame configured to elicit a joint transmission, to the device, of a MU packet over spatial streams respectively associated with the wireless stations. The device receives the MU packet over the spatial streams, where each spatial stream of the spatial streams is received by receive chains of the device. The device performs a channel estimation associated with each spatial stream of the spatial streams using each receive chain of the receive chains. The device determines that at least one spatial stream associated with the first wireless station is unavailable based on the channel estimation. The device processes the MU packet from the plurality of spatial streams without the at least one spatial stream.

A processor-implemented method includes receiving a signal representing a first encoded data and calculating an estimated timing offset and/or an estimated frequency offset associated with the signal. A correction of at least one of a timing offset or a frequency offset of the signal is performed based on the estimated timing offset and/or the estimated frequency offset, to produce a modified signal. An effective channel is subsequently detected based on the signal or the modified signal. A second encoded data is generated based on the modified signal, a known vector, at least one left singular vector of the effective channel, and at least one right singular vector of the effective channel. A signal representing the second encoded data is transmitted to a communication device for identification of contents of a message at a different processor.

An apparatus including a processor configured to receive a digital communication signal, wherein the digital communication signal includes a common reference signal and transmitted data. The processor determines a first interfering channel matrix for a first interfering cell based on a channel estimation of the common reference signal, and estimates a first power offset ratio and a first effective pre-coding matrix for the first interfering cell by evaluating a maximum likelihood metric, wherein the maximum likelihood metric is based on a first interfering channel correlation. The processor then reconstructs a channel covariance matrix based on the estimated first power offset ratio and the first effective pre-coding matrix and detects the transmitted data based on the reconstructed channel covariance matrix.

There are disclosed techniques (e.g., apparatus, methods) for estimating an impulse response of a linear system.

An apparatus is configured to generate a transmit signal on the basis of a first sequence. The apparatus is configured to obtain a receive signal and to multiply the receive signal with a second sequence, to obtain a modified receive signal, wherein the second sequence is different from the first sequence. The apparatus is configured to analog-to-digital, ADC, convert an integration result in order to obtain a sample value, the integration result being based on an integration of the modified receive signal over a period of time. The apparatus is configured to obtain an estimate of the impulse response on the basis of a plurality of sample values.

This application provides an uplink multi-station channel estimation method, a station (STA), and an access point (AP), which can be applied to an uplink multi-user multiple-input multiple-output scenario. The uplink multi-station channel estimation method includes: a STA generating a frame including a first group of training sequences and a second group of training sequences, and sending the frame to the AP. The AP calculates a frequency offset value between the STA and the AP based on the received first group of training sequences and the received second group of training sequences. The AP performs channel estimation based on the calculated frequency offset value. According to the technical solutions provided in this application, the AP can more accurately learn of frequency offset values between a plurality of STAs and the AP. This improves channel estimation precision.

A signal detection method for a MIMO-OFDM wireless communication system includes obtaining a channel matrix of each subcarrier through channel estimation for each MIMO-OFDM data packet in a plurality of MIMO-OFDM data packets; receiving a reception vector of each subcarrier; performing channel matrix preprocessing for the channel matrix of each subcarrier to generate a global dynamic K-value table, in which the global dynamic K-value table includes a global dynamic K-value corresponding to each search layer of each subcarrier; performing MIMO detection for each OFDM symbol in the MIMO-OFDM data packet, in which the MIMO detection includes performing the following steps for each subcarrier of a current OFDM symbol: reading channel matrix preprocessing results and reception vector of the current subcarrier; transforming the reception vector of the current subcarrier into an LR search domain; and performing K-best search for the current subcarrier to obtain an LR domain candidate transmission vector of the current subcarrier, in which a K-value applied to each search layer of the current subcarrier during the K-best search is a global dynamic K-value in the global dynamic K-value table corresponding to the search layer.

A method and system for performing quadrature amplitude modulation (QAM) decoding of a received signal includes finding for each layer a region in a first constellation diagram of the received signal, the region including a portion of the first constellation diagram, the portion having the same size of a second constellation diagram, and a first constellation order of the received signal is higher than a second constellation order of the second constellation diagram; and, for each layer: finding a first portion of bits based on bits that are constant among constellation points located in the region of the layer; decoding the received signal using a QAM decoder having the second constellation order to obtain a second portion of bits; adjusting the second portion of bits based on the region of the layer; and merging the first portion of bits with the second portion of bits to obtain a decoded symbol.

An apparatus includes a first communication device with multiple antennas, operably coupled to a processor and configured to access a codebook of transformation matrices. The processor generates a set of symbols based on an incoming data, and applies a permutation to each of the symbols to produce a set of permuted symbols. The processor transforms each of the permuted symbols based on at least one primitive transformation matrix, to produce a set of transformed symbols. The processor applies, to each of the transformed symbols, a precode matrix selected from the codebook of transformation matrices to produce a set of precoded symbols. The codebook of transformation matrices is accessible to a second communication device. The processor sends a signal to cause transmission, to the second communication device, of multiple signals, each representing a precoded symbol from the set of precoded symbols, each of the signals transmitted using a unique antenna from the plurality of antennas.