This invention presents a repeater enhanced MU-MIMO wireless communication system comprising a BS, a plural of repeaters, and a plural of UEs, where a repeater estimates the channel between itself and its upper communication node in the system, a repeater computes equalization coefficients based on the estimation of the channel coefficients, and a repeater applies the equalization coefficients to reduce the channel delay spread or increase the coherence bandwidth of the channel between communication nodes containing the BS, the UEs, or the repeaters.

Antenna-plexers for interference cancellation are provided herein. In certain embodiments, a wireless device includes an antenna, an antenna-plexer coupled to the antenna and configured to generate a feedback signal, a transmitter configured to transmit a transmit signal to the antenna by way of the antenna-plexer, a receiver configured to process a receive signal, and a feedback receiver configured to process the feedback signal from the antenna-plexer to provide compensation to the receive signal.

Antenna-plexers for interference cancellation are provided herein. In certain embodiments, a wireless device includes an antenna, an antenna-plexer coupled to the antenna and configured to generate a feedback signal, a transmitter configured to transmit a transmit signal to the antenna by way of the antenna-plexer, a receiver configured to process a receive signal, and a feedback receiver configured to process the feedback signal from the antenna-plexer to provide compensation to the receive signal.

A radio frequency (RF) receiver includes a transceiver, a programmable logic device (PLD), and a digitally tunable high-pass and low-pass filter bank. The transceiver is configured to receive a mission data file (MDF) specifying a plurality of RF frequencies to be tuned by the receiver and to convert the MDF into a binary file. The PLD is configured to receive the binary file from the transceiver and, based on the binary file, to transmit one or more commands that cause the filter bank to enter a selected one of a plurality of predefined filter states corresponding to one or more of the RF frequencies. In operation, the receiver receives an input signal and the filter bank dynamically filters the input signal in response to the one or more commands from the PLD.

An apparatus may be configured to receive a polar-encoded transmission comprising at least one intermediate node associated with a first configuration of frozen leaf nodes and information leaf nodes. The apparatus may further be configured to apply an FHT to a first set of values associated with a first intermediate node of the at least one intermediate node to generate a second set of values associated with the first intermediate node. The apparatus may also be configured to select, based on the second set of values, one or more paths associated with the first intermediate node for a SSCL decoding. The apparatus may further be configured to calculate a path metric for each of the selected one or more paths associated with the first intermediate node.

An apparatus may be configured to receive a polar-encoded transmission comprising at least one intermediate node associated with a first configuration of frozen leaf nodes and information leaf nodes. The apparatus may further be configured to apply an FHT to a first set of values associated with a first intermediate node of the at least one intermediate node to generate a second set of values associated with the first intermediate node. The apparatus may also be configured to select, based on the second set of values, one or more paths associated with the first intermediate node for a SSCL decoding. The apparatus may further be configured to calculate a path metric for each of the selected one or more paths associated with the first intermediate node.

A method for transmitting covertly employs three features in a novel combination to create a transmission waveform that has no detectable artifacts. First, the method employs spread spectrum, such as a direct sequence spread spectrum signal, to transmit the power level below the noise floor. Second, the method modulates the phase of each chip in the spread spectrum signal using a chaotic sequence. Third, the method filters the transmission signal using a pulse shaped filter to depress blind detection features in the amplitude modulation and higher order power spectral densities. The novel combination of these features results in a practically invisible and undetectable transmission waveform. Many other features are disclosed herein to optimize this combination.

A system includes an analog front-end configured to process a signal to obtain amplified beams, the signal being formed by pulses of a plurality of beams, pulses of each of the plurality of beams being generated according to a time-hopping modulation scheme, a plurality of radars coupled to the analog front-end, the plurality of radars configured to transmit each of the amplified beams at a different angle, and to receive reflections of the transmitted beams, and a plurality of correlators coupled to the plurality of radars through the analog front-end, the plurality of correlators being configured to process the reflections of the transmitted beams to obtain proximity measurements.

A system includes an analog front-end configured to process a signal to obtain amplified beams, the signal being formed by pulses of a plurality of beams, pulses of each of the plurality of beams being generated according to a time-hopping modulation scheme, a plurality of radars coupled to the analog front-end, the plurality of radars configured to transmit each of the amplified beams at a different angle, and to receive reflections of the transmitted beams, and a plurality of correlators coupled to the plurality of radars through the analog front-end, the plurality of correlators being configured to process the reflections of the transmitted beams to obtain proximity measurements.

A receiver includes: a correlation value calculation unit calculating a first cross-correlation function between a received signal, having a preamble spread with an up chirp and a down chirp, and the up chirp and calculating a second cross-correlation function between the received signal and the down chirp; a power value calculation unit calculating first and second power values of the first and second cross-correlation functions; a correlation power memory storing the first and second power values at each sample timing for one period of a spread code; a threshold determination unit determining first and second estimated timings from the first and second power values for one period of the spread code, respectively; and an estimation unit estimating a spread code timing of a transmitter using the first and second estimated timings, and performing coarse estimation of a frequency offset with respect to the transmitter.