Communication systems are described that use signal constellations, which have unequally spaced (i.e. geometrically shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR. In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d.sub.min, are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.

Communication systems are described that use signal constellations, which have unequally spaced (i.e. geometrically shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR. In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d.sub.min, are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.

To detect an error in pulse width in a communication scheme that identifies a start position of a message or expresses a data value using a pulse width of a pulse included in the message, provided is a receiving apparatus including a receiving section that receives a message including a synchronization pulse having a predetermined pulse width and a first data pulse having a pulse width corresponding to a value of first data; and an error detecting section that detects an error in response to the number of non-synchronization pulses that are consecutive after the synchronization pulse being outside a predetermined number range.

A power line communication apparatus includes a drive block including an actuator control circuit and a drive circuit and a communication block. The actuator control circuit generates a control pulse for controlling an actuator, and controls a transition timing of the control pulse during an operation period set within a communication cycle by a communication clock. The drive circuit controls a driving current of the actuator supplied from a DC power source through a power line based on the control pulse in which the transition timing is controlled. The communication block generates the communication clock, and modulates a current flowing through the power line in response to data to be transmitted during a signal transmission period different from the operation period, set within the communication cycle.

Aspects of the subject disclosure may include, for example, a node device includes an interface configured to receive first signals. A plurality of coupling devices are configured to launch the first signals on a transmission medium as a plurality of first guided electromagnetic waves at corresponding plurality of non-optical carrier frequencies, wherein the plurality of first guided electromagnetic waves are bound to a physical structure of the transmission medium. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, a node device includes an interface configured to receive first signals. A plurality of coupling devices are configured to launch the first signals on a transmission medium as a plurality of first guided electromagnetic waves at corresponding plurality of non-optical carrier frequencies, wherein the plurality of first guided electromagnetic waves are bound to a physical structure of the transmission medium. Other embodiments are disclosed.

An apparatus comprises a plurality of sampling circuits configured to receive a non-Non Return to Zero (non-NRZ) data signal; and a control circuit coupled to the plurality of sampling circuits, wherein the control circuit is configured to provide one or more control signals indicating whether to decrease or increase a frequency of a clock signal associated with the non-NRZ data signal based on the non-NRZ data signal.

A PAM reception circuit includes a first comparison circuit that outputs a first bit value in two-bit values based on a result of a comparison between a reception signal of pulse amplitude modulation 4 in which the two-bit values are associated with four potential levels divided by three threshold values by gray codes and a first threshold value which is a center of the three threshold values, an absolute value circuit that outputs an absolute value of a difference between the reception signal and the first threshold value or a negative value obtained by inverting a sign of the absolute value from a positive sign to a negative sign, and a second comparison circuit that outputs a second bit value in the two-bit values based on a result of a comparison between a second threshold value which is larger than the first threshold value in the three threshold values.

Embodiments of the present invention provide a power amplifier, a radio remote unit RRU, and a base station. A multiphase pulse width modulator performs modulation to generate N multiphase pulse-width modulation PWM signals. The multiphase pulse-width modulation PWMn signal may be amplified. The multiphase pulse-width modulation PWMn signal may be filtered and a combination may be performed at a drain or a collector of a power amplifier transistor. According to the new radio frequency amplifier in accordance with the disclosure, envelope feeding loop inductance can be effectively reduced, so that video bandwidth is increased and DPD correction performance is improved.

Aspects of the present disclosure relate to a wireless device including one or more processors and a memory storing processor-readable instructions that, when executed by the one or more processors, causes the wireless device to perform operations. The operations include receiving a first message indicating a reuse transmission opportunity associated with a downlink transmission from a first device to a second device. The operations further include determining to participate in the reuse transmission opportunity based at least in part on the downlink transmission. The operations further include, during the reuse transmission opportunity, transmitting uplink communications to the first device concurrently with the downlink transmission from the first device to the second device in the same frequency channel.