A transmission apparatus including the number of antennas different from a reception apparatus and performing transmission by SC-MIMO to and from the reception apparatus includes a training signal generation unit that generates a known signal predetermined, a CP addition unit that adds a CP to each symbol of a transmission signal including the known signal, a weight generation unit that generates a transmission weight based on a transposed adjugate matrix that is a product of a channel matrix estimated based on the known signal by the reception apparatus and a complex conjugate transpose of the channel matrix, and a transmission beam formation unit that uses the transmission weight to form a transmission beam for the transmission signal where the CP is added.

Various strategies and devices for same are disclosed to correct for/mitigate frequency offset (such as due to differing accuracies between an oscillator of a transmitting device and an oscillator of a receiving device) and Doppler shift (such as due to a changing relative position between a receiving device and a transmitting device). These strategies may be employed in a MIMO setting, such as, e.g. a stationary base station and a plurality of terminal devices (e.g. user devices, mobile stations, etc.), in which the transmissions for each terminal device may be associated with a different frequency offset and a different Doppler shift.

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 method of channel estimation in a communication system includes the steps of: receiving at least one input signal associated with at least one data stream, the input signal having reference symbols and data symbols; processing the at least one input signal in a slot-wise manner; performing a channel estimation by taking at least one reference symbol per input signal into account, which is used to equalize the respective input signal and to assign the symbols to the at least one data stream, thereby generating a processed signal for each independent data stream, and processing further the processed signal while performing an additional channel estimation for each independent data stream, wherein the reference symbols and the data symbols are taken into account for the additional channel estimation. Further, a signal processing system is described.

Embodiments herein provide a method of estimating channel states of a plurality of user equipments (UEs) in a single instance. The method includes receiving pilot samples from the plurality of UEs. The method includes selecting a predetermined number of tones, wherein the channel associated with each UE across the selected pre-determined number of tones is same. The method includes collecting the received pilot samples from each pilot symbol and stacking the received pilot samples as a vector. Further, the method includes constructing a matrix. The matrix includes known pilot values used by each UE. Furthermore, the method includes estimating channel states of the plurality of UEs by applying a filter on the vector formed from the received pilot samples. The number of channel states to be estimated is reduced by selecting the pre-determined number of tones.

A method and apparatus are provided for reducing the number of pilot symbols within a MIMO-OFDM communication system, and for improving channel estimation within such a system. For each transmitting antenna in an OFDM transmitter, pilot symbols are encoded so as to be unique to the transmitting antenna. The encoded pilot symbols are then inserted into an OFDM frame to form a diamond lattice, the diamond lattices for the different transmitting antennae using the same frequencies but being offset from each other by a single symbol in the time domain. At the OFDM receiver, a channel response is estimated for a symbol central to each diamond of the diamond lattice using a two-dimensional interpolation. The estimated channel responses are smoothed in the frequency domain. The channel responses of remaining symbols are then estimated by interpolation in the frequency domain.

A method includes transmitting a training signal derived from a sequence, the training signal facilitates an estimation of a channel impulse response (CIR) for a communications channel between a transmit antenna of the device and a receive antenna of the device, estimating the CIR for the communications channel, and receiving signals corresponding to a first transmission at the receive antenna. The method also includes cancelling self-interference present in the received signals in accordance with the estimated CIR, the self-interference arising from a second transmission made by the transmit antenna of the device, thereby producing an interference canceled received signal, and processing the interference canceled received signal.

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 channel matrix representing characteristics of a multi-path channel between a transmitter device (210) equipped with multiple transmitter antennas (211, 212, 213, 214, 215) and at least one receiver device (220, 230, 240) equipped with one or more receiver antennas (221, 222, 231, 232, 241, 242). The channel matrix is organized in one or more channel vectors each associated with a corresponding one of the one or more receiver antennas (221, 222, 231, 232, 241, 242). An iterative optimization algorithm is applied to determine a precoding matrix from the channel matrix. At least one step size of the iterative optimization algorithm is set depending on a vector norm of at least one of the channel vectors. Multi-antenna transmission by the transmitter device (210) is then controlled based on the determined precoding matrix.

Various strategies and devices for same are disclosed to correct for/mitigate frequency offset (such as due to differing accuracies between an oscillator of a transmitting device and an oscillator of a receiving device) and Doppler shift (such as due to a changing relative position between a receiving device and a transmitting device). These strategies may be employed in a MIMO setting, such as, e.g. a stationary base station and a plurality of terminal devices (e.g. user devices, mobile stations, etc.), in which the transmissions for each terminal device may be associated with a different frequency offset and a different Doppler shift.