Disclosed are a wireless transmitter and a reference signal transmission method that improve channel estimation accuracy. In a terminal, which transmits a reference signal using n (n is a non-negative integer 2 or greater) band blocks (which correspond to clusters here), which are disposed with spaces therebetween in a frequency direction, a reference signal controller switches the reference signal formation method of a reference signal generator between a first formation method and a second formation method based on the number (n) of band blocks. In addition, a threshold value setting unit adjusts a switching threshold value based on the frequency spacing between band blocks. Thus, the reference signal formation method can be selected with good accuracy and, as a result, channel estimation accuracy is further improved.

Disclosed is a blind authentication method for a frequency selective fading channel based on a smoothing technique. The method includes: transmitting carrier signals to a frequency selective fading channel having multiple paths, where each carrier signal includes an authentication signal, a pilot signal and an information signal, receiving the carrier signals, performing BKIC processing on a carrier signal in each path to obtain a target signal, and performing differential signal processing on the target signal to obtain a target authentication signal, obtaining a reference signal based on a key and the pilot signal in the each path, performing the differential signal processing on the reference signal to obtain a reference authentication signal, and calculating a correlation between the target authentication signal and the reference authentication signal to obtain a test statistic; and comparing the test statistic with a prescribed threshold to determine whether the carrier signal in the each of the plurality of paths can pass authentication.

A millimeter-wave communication system includes a transmitter and a receiver. The transmitter is configured to be connected to a waveguide that is transmissive at millimeter-wave frequencies, the waveguide having a propagation parameter that varies with frequency at the millimeter-wave frequencies. The transmitter is configured to generate a millimeter-wave signal comprising multiple sub-carriers that are modulated with data, wherein each sub-carrier is modulated with a respective portion of the data and is subjected to only a respective fraction of a variation in the propagation parameter, and to transmit the millimeter-wave signal into a first end of the waveguide. The receiver is configured to receive the millimeter-wave signal from a second end of the waveguide, and to extract the data from the multiple sub-carriers.

A method and system for providing sub-band whitening are herein provided. According to one embodiment, a method includes deriving an estimated noise plus interference variance (NIVar) based on at least one legacy-long training field (LLTF) symbol from an LLTF signal; and updating an interference whitening (IW) factor by using a sub-band NIVar.

There is provided a technique of decoding an uplink in a multiple input multiple output wireless communication system in an open radio access network having an open distributed unit (O-DU) and an open radio unit (O-RU). The O-DU (a) constructs a combining matrix for a resource block, and (b) sends the combining matrix to the O-RU. The O-RU (a) utilizes the combining matrix to compress signals on N.sub.R antennas per subcarrier into M values, where N.sub.R is a number of antennas, and M is less than N.sub.R, and (b) sends the M values per subcarrier to the O-DU.

System and methods enabling radio communications that are operating in noisy environments using OFDM (Orthogonal Frequency Division Multiplexing) are disclosed. A spread OFDM transmitter that generates OFDM symbols that may include multiple copies of IFFT symbols is disclosed. A spread OFDM receiver is disclosed for receiving the spread OFDM symbols. Other methods for symbol detection, frequency offset correction, and equalization are disclosed.

An operation method of a receiving apparatus may comprise: receiving an N-th data block belonging to a frame including a plurality of data blocks from a transmitting apparatus, each of the plurality of data blocks including a data period and a UW period; storing a first UW received in a UW period of the N-th data block in a buffer; receiving an (N+1)-th data block belonging to the frame from the transmitting apparatus; estimating a phase noise in a time domain by combining the first UW with a second UW received in a UW period of the (N+1)-th data block; and applying time-domain compensation according to the estimated phase noise to the (N+1)-th data block, and demodulating data of the (N+1)-th data block, wherein the first UW and the second UW are configured with a same sequence.

A method for precoding to mitigate nonlinear distortions and a precoder for performing the same are disclosed. The precoder for mitigating distortions of a communication signal may include a filter configured to generate a filtering signal based on a third signal and filter coefficients corresponding to a selected signal generated based on a first signal, a second signal, and the third signal, and a modulo operator configured to generate the third signal by performing a modulo operation on the second signal, wherein the second signal is generated based on the first signal and the filtering signal.

Circuits, methods, and apparatus that provide improved data recovery for data transmitted through a channel of limited bandwidth. An example can provide circuits, methods, and apparatus that can equalize losses in a physical channel. This equalization can provide an overall channel response that is more consistent and uniform.

It is an objective of the current disclosure to design a novel communications system capable of offering improvement in channel capacity compared to current communications systems. To this end, the disclosure teaches how to add new information to a select number of Degrees of Freedom (DOF), through three design steps. All three steps aim to design the system such that the minimum required average received Signal-to-Noise Ratio (SNR) is reduced for a given desired capacity and for a given specified mask. The first design step identifies the select number of DOF required for achieving the desired capacity. The second design step enhances the contribution of the selected DOF by matching them to the specified mask. This step aims to have the transmitted signal comply with the specified mask. The third design step randomizes the DOF using a pseudo-random phase. This step aims to reduce the required average received SNR.