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.

Wireless communication wherein channel estimation accuracy is improved while keeping the position of each bit in a frame, even when a modulation system having a large modulation multiple value is used for a data symbol. An encoding operation encodes and outputs transmitting data (bit string) and a bit converting operation converts at least one bit of a plurality of bits constituting a data symbol to be used for channel estimation, among the encoded bit strings, into 1 or 0. A modulating operation modulates the bit string inputted from the bit converting operation by using a single modulation mapper and a plurality of data symbols are generated.

A user station for a bus system and a method for the wideband communication in a bus system are provided. The user station includes a communications-control unit for preparing or reading at least one message for/from at least one further user station of the bus system, in which an exclusive, collision-free access of a user station to a bus line of the bus system is ensured at least intermittently; the communications-control unit is designed to prepare channel-status information according to a time sequence for the transmission specified in the bus system for the user station so that the user station does not have to send the channel-state information in each message, and the channel-status information includes information for ascertaining the channel characteristic between the user station and the further user station of the bus system to which the message is to be sent.

Methods and devices for receiving or transmitting a wireless packet are described. A wireless packet includes a short training field (STF) and a channel estimation field (CEF). The receiver determines whether the received STF matches an assigned STF assigned for a target link, by performing cross-correlation between the STF and a component sequence from a set of at least four different component sequences which are pairs of Golay sequences. The cross-correlation output is compared with an expected output. When the received STF matches the assigned STF, the wireless packet is considered a target packet. A channel estimation is performed using a cross-correlation of the received CEF with an assigned CEF assigned for the target link. The assigned CEF is from a set of two or more CEFs, where each CEF is formed using the set of component sequences, and the CEFs are pairwise zero-correlation zone (ZCZ) sequences.

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 processing module for a transmitter device configured to provide for generation of a signal comprising at least one frame for transmission by the transmitter device to a receiver device, the processing module configured to provide for processing of an input pulse stream comprising a stream of pulses representative of data, to provide an output pulse stream, each pulse of the pulse streams having one of two states defining the phase with which a carrier wave is modulated; the processing module configured to; divide the input pulse stream into consecutive groups of pulses; and for each group of pulses, based on determination that the first two or more consecutive pulses of the group have the same polarity, provide for addition of at least one dummy pulse to the group directly after the first two or more consecutive pulses, with an opposite polarity.

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.

This disclosure describes systems, methods, and devices related to a trigger-based null data packet (NDP) for channel sounding system. A device may send a trigger frame to a group of station devices, the group of station devices including a first station device, the trigger frame indicating a high efficiency (HE) long training field (HE-LTF) mode and a guard interval duration. The device may identify a HE trigger-based (TB) null data packet (NDP) received from the first station device, the HE TB NDP including a first packet extension field, wherein the HE TB NDP is associated with the HE-LTF mode and the guard interval duration indicated in the trigger frame. The device may send a downlink NDP including a second packet extension field, a second HE-LTF mode, and a second guard interval duration. The device may determine channel state information based on HE TB NDP received from the first station device.

Methods and devices for receiving or transmitting a wireless packet are described. A wireless packet includes a short training field (STF) and a channel estimation field (CEF). The receiver determines whether the received STF matches an assigned STF assigned for a target link, by performing cross-correlation between the STF and a component sequence from a set of at least four different component sequences which are pairs of Golay sequences. The cross-correlation output is compared with an expected output. When the received STF matches the assigned STF, the wireless packet is considered a target packet. A channel estimation is performed using a cross-correlation of the received CEF with an assigned CEF assigned for the target link. The assigned CEF is from a set of two or more CEFs, where each CEF is formed using the set of component sequences, and the CEFs are pairwise zero-correlation zone (ZCZ) sequences.

A channel equalizer includes a first transformer, an estimator, an average calculator, a second transformer, a coefficient calculator, a compensator, and a third transformer. The first transformer converts normal data into frequency domain data, where a known data sequence is periodically repeated in the normal data. The estimator estimates channel impulse responses (CIR) during known data intervals adjacent to each normal data block. The average calculator calculates an average value of the CIRs. The second transformer converts the average value into frequency domain data. The coefficient calculator calculates equalization coefficients using the average value, and the compensator compensates channel distortion of each normal data block using the coefficients. The third transformer converts the compensated data block into time domain data.