The embodiments of the present disclosure disclose a method for uplink multiuser data transmission and a system for uplink multiuser multiple input multiple output. The method includes: sending, by an access point AP, indication information to at least two stations STAs, wherein the indication information is used for indicating that the at least two STAs perform an uplink multiuser data transmission; receiving, by the AP, uplink data sent by the at least two STAs through channels from the at least two STAs to the AP, respectively; and demodulating, by the AP, the uplink data sent by the at least two STAs using receiving beams corresponding to pre-estimated channels from the at least two STAs to the AP, respectively.

The embodiments of the present disclosure disclose a method for uplink multiuser data transmission and a system for uplink multiuser multiple input multiple output. The method includes: sending, by an access point AP, indication information to at least two stations STAs, wherein the indication information is used for indicating that the at least two STAs perform an uplink multiuser data transmission; receiving, by the AP, uplink data sent by the at least two STAs through channels from the at least two STAs to the AP, respectively; and demodulating, by the AP, the uplink data sent by the at least two STAs using receiving beams corresponding to pre-estimated channels from the at least two STAs to the AP, respectively.

This disclosure provides systems, devices, apparatus and methods, including computer programs encoded on storage media, for wireless communication. In one aspect, an access point for wireless communications may include a transceiver; a memory; and a processor communicatively coupled to the transceiver and the memory, the processor being configured to: determine an interference level on a selected bandwidth; selectively transmit, via the transceiver, a clear-to-send (CTS)-to-self frame based on the determined interference level; and initiate a sounding sequence based on the transmitted CTS-to-self frame.

An OFDM modulator including a predistortion module configured to receive the N.sub.c consecutive data carriers and configured to compensate for distortion subsequently introduced by a polyphase filter bank connectable to the output of the OFDM modulator, a transformation module configured to apply a discrete inverse Fourier transform of constant size N.sub.IDFT independently of the numbering and transmission band used by the OFDM transmitter including the OFDM modulator, a filling module, the input of which is connected to the output of the predistortion module, and the output of which is connected to the input of the transformation module, and configured to insert (N.sub.IDFT?N.sub.c) null carriers in succession to the N.sub.c consecutive data carriers independently of the parity of the index i associated with the OFDM modulator.

Techniques are described for wireless communication. One method includes identifying a plurality of channel responses corresponding to a plurality of channels. Each channel of the plurality of channels corresponds to a pairing of a transmit antenna with a receive antenna. Each channel response of the plurality of channel responses corresponds to a plurality of tone subsets. The method also includes selecting, for each channel of the plurality of channels, a subset of non-frequency domain components of the channel response for the channel, and transmitting, for at least one channel of the plurality of channels, at least one subset of channel state information (CSI). The at least one subset of CSI is based at least in part on at least one of the selected subsets of non-frequency domain components.

The present disclosure discloses a method and apparatus for estimating a frequency offset. The method includes: reconstructing an estimated channel value of a target user and an estimated channel value of a non-target user to obtain a reconstructed estimated channel value of the target user and a reconstructed estimated channel value of the non-target user; calculating frequency domain received data of a target user's local pilot frequency at which interference has been cancelled by using frequency domain data of a subcarrier occupied by the target user, frequency domain data of a subcarrier occupied by the adjacent non-target user, and the reconstructed estimated channel value of the target user and the reconstructed estimated channel value of the non-target user; and determining an estimated frequency offset value by using the target user's local pilot frequency at which interference has been cancelled and the frequency domain received data.

The present disclosure relates to a pre-5.sup.th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4.sup.th-Generation (4G) communication system such as Long Term Evolution (LTE). A method and an apparatus for channel estimation in a wireless communication system are provided. According to various embodiments of the present disclosure, an method of a receiving apparatus in a wireless communication system includes: estimating channel tap values by using a first reference signal; and estimating an effective channel regarding a second reference signal, based on channel tap indexes corresponding to values greater than or equal to a threshold from among the channel tap values. According to various embodiments of the present disclosure, the receiving apparatus can more exactly estimate an effective channel, and can achieve a lower BLER even in a high SNR region.

The disclosure relates to a method (60) performed in a network node (2) for estimating a channel. The network node (2) controls an antenna array (3) comprising a number N of antennas (51, . . . , 5N) in one or more spatial dimensions. The network node (2) comprises a receiver (72) receiving signals from the antenna array (3). The method (60) comprises: obtaining (61) matched filter channel estimates for each sub-carrier and antenna of a signal received by the antennas (51, . . . , 5N), the signal comprising a number K of frequency sub-carriers; arranging (62) the obtained matched filter channel estimates in a first multi-dimensional array, wherein time or frequency domain samples of the matched filter channel estimates are arranged along a first dimension and wherein a second dimension is a first spatial dimension of the number N of antennas, wherein the matched filter channel estimates are ordered in the first multi-dimensional array such as to reflect the physical location in space of the antennas (51, . . . , 5N); applying (63) an orthogonal transform to the first multi-dimensional array, providing a second multi-dimensional array; de-noising (64) the second multi-dimensional array, providing a third multi-dimensional array; applying (65) the inverse of the orthogonal transform to the third multi-dimensional array, providing channel estimates for all branches of the receiver (72). The disclosure also relates to corresponding network node, computer program and computer program products.

The present disclosure discloses a method and apparatus for estimating a frequency offset. The method includes: reconstructing an estimated channel value of a target user and an estimated channel value of a non-target user to obtain a reconstructed estimated channel value of the target user and a reconstructed estimated channel value of the non-target user; calculating frequency domain received data of a target user's local pilot frequency at which interference has been cancelled by using frequency domain data of a subcarrier occupied by the target user, frequency domain data of a subcarrier occupied by the adjacent non-target user, and the reconstructed estimated channel value of the target user and the reconstructed estimated channel value of the non-target user; and determining an estimated frequency offset value by using the target user's local pilot frequency at which interference has been cancelled and the frequency domain received data.

Certain aspects of the present disclosure relate to techniques for estimating a channel using soft-windowing. A user equipment (UE) may determine, based on a cyclic prefix (CP) length of a channel, a timing window for sampling reference signals transmitted on the channel, determine a set of weights to apply to samples obtained within the determined timing window, wherein each weight corresponds to a sample obtained within the determined window, and estimate the channel by applying the weights to the samples.