The present disclosure provides a method of performing, by a plurality of user equipments (UEs), a federated learning in a wireless communication system. More specifically, the method performed by one UE of the plurality of UEs comprises receiving, from a base station (BS), control information related to a scheduling of a resource on which the one UE repeatedly transmits a local parameter of the one UE, wherein a global parameter for the federated learning is updated based on respective local parameters of the plurality of UEs: transmitting, to the BS, a first signal including the local parameter of the one UE on a first resource scheduled based on the control information; and transmitting, to the BS, a second signal including the local parameter of the one UE on a second resource that is scheduled based on the control information and is different from the first resource, wherein the first signal and the second signal are transmitted based on the first signal and the second signal being in a complex conjugate relationship.

Systems and methods for detecting and estimating parameters for a phase-modulated signal in a continuous manner with near-optimal performance. The methods generate these estimates using streaming (or on-the-fly) calculations and so are suitable for hardware-based implementation. These estimates can be used as part of standard pulse descriptor words for radar and other pulsed or continuous signals that are reported by an electronic warfare receiver to a processing and display system. Also, the methods can be computed using sub-sampling methods in order to reduce overall computations.

A system and method for estimating clock drift in underwater instruments is provided. The method can include transmitting a signal from a source to a plurality of underwater receivers or a single receiver. Upon recovery of the underwater receivers, an initial sampling frequency value can be used to generate received data waveforms from data stored on each underwater device. The generated received waveforms can be used to generate a channel estimate for each receiver, and the channel estimates can be used to provide an estimate of the source motion during the transmission. The estimated source motion can then be used to estimate the clock drift.

Methods and systems for obtaining improved channel estimates for frequency-multiplexed data transmissions such as OFDM, OFDMA, or SC-FDMA transmissions overcome the limitations of the static assumption by using a polynomial or other fitting function to fit and model the frequency dependence of the channel coefficients, so that estimates can be applied to larger subcarrier groups. Some embodiments provide channel estimates for a singular signal source, while other embodiments provide joint channel estimates for a plurality of signal sources. In embodiments, selection of the fitting functions is influenced by all previously determined channel estimates. In some embodiments, a tracking algorithm allows use of the lowest possible order of polynomial or other fitting function to model the frequency dependence of the channel coefficients, whereby the channel estimate is continually shifted in frequency while the order of the polynomial or other fitting function remains low.

Embodiments described herein include methods and systems for measuring channel impulse responses in a digital communication system. Specifically, statistical properties of the received signals at the receiver of the digital communication system are analyzed to compute, in real time, channel coefficients indicative of the channel state information, which may be time-dependent, without the use of a training signal.

A receiver for use in a wireless communication system to receive signals transmitted over a wireless channel. The receiver includes a plurality of radio-frequency (RF) chains coupled a plurality of antennas. Each RF chain has at least one-bit analog-to-digital converter (ADC) to convert each measurement of an analog signal received by the antenna into at least one bit of information representing a result of a comparison of the measurement with a randomly selected threshold to produce a sequence of bits and a corresponding sequence of thresholds. Each bit in the sequence of bits represents a relative value of the measurement of the analog signal with respect to a threshold from the corresponding sequence of thresholds. A processor coupled to the plurality of RF chains estimates parameters of the wireless channel using the sequences of bits and the corresponding sequences of thresholds received from the plurality of RF chains.

Methods and systems are described for jointly processing multiple sectors in a wireless communication network. In one aspect, a first antenna serving a first sector is associated with a second antenna serving a second sector for joint processing. First and second antenna data is received. A plurality of wireless users associated with at least one of the first or second antenna data to model for channel estimation is determined, including an interfering wireless user connected via a third antenna serving a third sector not currently being jointly processed with the first or second antenna data. Channel estimates are determined for the plurality of wireless users. The first and second antenna data is jointly processed. Interference from the wireless user connected via a third antenna is suppressed based on a determined corresponding channel estimate for the wireless user and other received information for the wireless user.

Methods and systems for obtaining improved joint channel estimates for a multi-user, frequency-multiplexed data transmission such as SC-FDMA or OFDM begins by estimating separate contributions of users (and/or other signal sources) to the received signal based on joint frequency domain channel estimates. A reduced data set is obtained by subtracting contributions of one or more users from the received data, leaving only the estimated contributions of the remaining users, with noise and residual estimation error signal. Time domain joint channel estimation is then performed on the reduced data set, which is feasible because the number of users has been reduced. In exemplary embodiments, the reduced data set includes only one estimated user contribution. This process is repeated to obtain channel estimates for all of the users. The method can be repeated by using the channel estimates to re-estimate the user contributions and calculate revised channel estimates.

A symbol rate estimation device includes: a power spectrum density (PSD) generating unit, estimating a power of an input signal to generate a PSD; a cut-off frequency index outputting unit, outputting a cut-off frequency index according to the power; and a symbol rate calculating unit, calculating a symbol rate of the input signal according to the cut-off frequency index.

Provided is a data decoding method of a wireless communication device. The method includes receiving a plurality of sub-frames. The method further includes accumulating data signals respectively included in each of the plurality of sub-frames. The method further includes updating a channel estimation value based on reference signals included in a most recent sub-frame of the plurality of sub-frames. The method further includes calculating a log likelihood ratio (LLR) based on the accumulated data signals and the updated channel estimation value. Furthermore, the method includes decoding data based on the LLR.