An augmented reality (AR) system time-reverses a detection signal and a data signal based on a location detection signal, and outputs the time-reversed detection signal and data signal. Accordingly, data transmission efficiency may increase.

In an embodiment a device includes a first circuit and a second circuit, wherein the first circuit is configured to generate a fourth signal and a fifth signal by applying the phase shift respectively to a first signal and to a second signal and deliver a sixth signal corresponding to a sampling over one bit of the fourth signal, a seventh signal corresponding to a sampling over one bit of the fifth signal, an eighth signal corresponding to a sampling over one bit of a difference between the fourth and fifth signals, and a ninth signal corresponding to a sampling over one bit of a sum between the fourth and fifth signals, wherein the second circuit is configured to receive the sixth, seventh, eighth, and ninth signals and determine, during a first phase where the first and second signals are representative of a first known symbol of a QPSK constellation, a state of a first bit from among a first state and a second state based on the eighth and ninth signals.

A method and structure for probabilistic shaping and compensation techniques in coherent optical receivers. According to an example, the present invention provides a method and structure for an implementation of distribution matcher encoders and decoders for probabilistic shaping applications. The techniques involved avoid the traditional implementations based on arithmetic coding, which requires intensive multiplication functions. Furthermore, these probabilistic shaping techniques can be used in combination with LDPC codes through reverse concatenation techniques.

A digital frequency modulation receiver includes a phase capturer, an adder, a digital filter and a phase estimator. The phase estimator is used to generate a first phase value according to an input signal. The adder is coupled to the phase estimator for subtracting a second phase value from the first phase value to generate a phase difference. The digital filter is coupled to the adder for performing a filtering calculation with the phase difference so as to generate a frequency variation signal. The phase estimator is coupled to the digital filter and the adder so as to update the second phase value according to the frequency variation signal.

A return channel system for ultra-small aperture terminals has a spreader that receives an input signal and outputs a spread spectrum signal having multiple replicated signals with a lower power than the input signal. A de-spreader includes a de-multiplexer that receives the spread spectrum signal via satellite. The de-multiplexer separates the spread spectrum signal into a first channel having a first signal and a second channel having a second signal. The de-spreader also has an offset compensation circuit having a phase estimator configured to estimate a phase offset between a phase of the first signal and a phase of the second signal. And a phase adjustor that receives the second signal and adjusts the phase of the second signal to align with the phase of the first signal to provide a phase-adjusted second signal. A summer combines the first signal with the phase-adjusted second signal to provide a composite signal.

Embodiments of an access point (AP), station (STA) and method for communication in accordance with frame formats of varying sizes of pilot portions are generally described herein. The AP may transmit, to the STA, a first downlink frame in accordance with a first downlink frame format. The AP may receive, from the STA, a phase noise measurement of the STA. The AP may select, based at least partly on the received phase noise measurement, a downlink frame format to enable a phase noise compensation at the STA. The AP may generate a downlink frame in accordance with the second downlink frame format, and may transmit the second downlink frame to the STA. In some cases, the first and second downlink frame formats may be based on different ratios of pilot portions to data portions.

A method and structure for probabilistic shaping and compensation techniques in coherent optical receivers. According to an example, the present invention provides a method and structure for an implementation of distribution matcher encoders and decoders for probabilistic shaping applications. The techniques involved avoid the traditional implementations based on arithmetic coding, which requires intensive multiplication functions. Furthermore, these probabilistic shaping techniques can be used in combination with LDPC codes through reverse concatenation techniques.

An augmented reality (AR) system time-reverses a detection signal and a data signal based on a location detection signal, and outputs the time-reversed detection signal and data signal. Accordingly, data transmission efficiency may increase.

In an embodiment a device includes a first circuit and a second circuit, wherein the first circuit is configured to generate a fourth signal and a fifth signal by applying the phase shift respectively to a first signal and to a second signal and deliver a sixth signal corresponding to a sampling over one bit of the fourth signal, a seventh signal corresponding to a sampling over one bit of the fifth signal, an eighth signal corresponding to a sampling over one bit of a difference between the fourth and fifth signals, and a ninth signal corresponding to a sampling over one bit of a sum between the fourth and fifth signals, wherein the second circuit is configured to receive the sixth, seventh, eighth, and ninth signals and determine, during a first phase where the first and second signals are representative of a first known symbol of a QPSK constellation, a state of a first bit from among a first state and a second state based on the eighth and ninth signals.

A method and structure for compensation techniques in coherent optical receivers. The present invention provides a coherent optical receiver with an improved 8×8 adaptive MIMO (Multiple Input, Multiple Output) equalizer configured within a digital signal processor (DSP) to compensate the effects of transmitter I/Q skew in subcarrier multiplexing (SCM) schemes. The 8×8 MIMO equalizer can be configured such that each of the 8 outputs is electrically coupled to 3 of 8 inputs, wherein each of the input-output couplings is configured as a filter. The method includes compensating for impairments to the digital conversion of an optical input signal via the 8×8 MIMO equalizer following other signal processing steps, such as chromatic dispersion (CD)/polarization-mode dispersion (PMD) compensation, carrier recovery, timing synchronization, and cycle slip correction.