A circuit for direct current (DC) offset estimation comprises a quantile value circuit and a signal processor. The quantile value circuit determines a plurality of quantile values of an input signal and includes a plurality of quantile filters. Each quantile filter includes a comparator, a level shifter, a monotonic transfer function component, and a latched integrator. The comparator compares the input signal and a quantile value. The level shifter shifts the output of the comparator. The monotonic transfer function component determines the magnitude of the shifted signal and provide a transfer function signal. The latched integrator suppresses transient characteristics of the transfer function signal and provide the quantile value. The signal processor is configured to calculate a weighted average of the quantile values to yield a DC offset estimate.

In optical receivers, cancelling the DC component of the incoming current is a key to increasing the receiver's effectiveness, and therefore increase the channel capacity. Ideally, the receiver includes a DC cancellation circuit for removing the DC component; however, in differential receivers an offset may be created between the output voltage components caused by the various amplifiers. Accordingly, an offset cancellation circuit is required to determine the offset and to modify the DC cancellation circuit accordingly.

In optical receivers, cancelling the DC component of the incoming current is a key to increasing the receiver's effectiveness, and therefore increase the channel capacity. Ideally, the receiver includes a DC cancellation circuit for removing the DC component; however, in differential receivers an offset may be created between the output voltage components caused by the various amplifiers. Accordingly, an offset cancellation circuit is required to determine the offset and to modify the DC cancellation circuit accordingly.

Techniques are disclosed relating to DC interference cancelation in received wireless signals. Disclosed techniques may be performed in the digital domain, in conjunction with analog cancelation techniques. In some embodiments, a receiver apparatus operates a local oscillator at a frequency corresponding to a particular pilot symbol in a received wireless signal. In some embodiments the receiver estimates DC interference at the frequency based on the received pilot symbol (this may be facilitated by the fact that the contents of pilot symbols are known, because they are typically used for channel estimation). In some embodiments, the receiver apparatus is configured to cancel the DC interference based on the estimate to determine received data in subsequently received signals at the frequency. Disclosed techniques may allow narrowband receivers to efficiently use more of their allocated frequency bandwidth, rather than wasting bandwidth near the frequency of the local oscillator.

A local oscillator outputs a local oscillation signal. A orthogonal detector subjects a received signal to orthogonal detection by using the local oscillation signal so as to output an I-phase baseband signal and a Q-phase baseband signal. A first HPF and a second HPF reduce a direct current component of each of the I-phase baseband signal and the Q-phase baseband signal. A demodulator demodulates the I-phase baseband signal and the Q-phase baseband signal output from the first HPF and the second HPF. A distribution detector detects an unevenness in a distribution of the I-phase baseband signal and the Q-phase baseband signal with the reduced direct current component. When the distribution detector detects an unevenness in the distribution, the distribution detector changes a status of the first HPF and the second HPF.

An ultra-low power back-channel receiver is presented that demodulates binary a FSK back-channel signal embedded in 5.8 GHz IEEE 802.11a Wi-Fi OFDM packets. The architecture of the back-channel receiver employs a two-step down-conversion where the first mixing stage downconverts using the third harmonic of the local oscillator for power efficiency. The LP-65 nm CMOS receiver consumes 335 W with a sensitivity of 72 dBm at a BER of 10.sup.3 and data-rate of 31.25 kb/s. The radio uses a balun and a 250 kHz reference crystal as external components. The receiver uses a 1V supply voltage for analog blocks, and 0.85V for digital blocks including the local oscillator and the frequency-locked loop circuits.

Techniques are disclosed relating to DC interference cancelation in received wireless signals. Disclosed techniques may be performed in the digital domain, in conjunction with analog cancelation techniques. In some embodiments, a receiver apparatus operates a local oscillator at a frequency corresponding to a particular pilot symbol in a received wireless signal. In some embodiments the receiver estimates DC interference at the frequency based on the received pilot symbol (this may be facilitated by the fact that the contents of pilot symbols are known, because they are typically used for channel estimation). In some embodiments, the receiver apparatus is configured to cancel the DC interference based on the estimate to determine received data in subsequently received signals at the frequency. Disclosed techniques may allow narrowband receivers to efficiently use more of their allocated frequency bandwidth, rather than wasting bandwidth near the frequency of the local oscillator.

In optical receivers, cancelling the DC component of the incoming current is a key to increasing the receiver's effectiveness, and therefore increase the channel capacity. Ideally, the receiver includes a DC cancellation circuit for removing the DC component; however, in differential receivers an offset may be created between the output voltage components caused by the various amplifiers. Accordingly, an offset cancellation circuit is required to determine the offset and to modify the DC cancellation circuit accordingly.

A local oscillator outputs a local oscillation signal. A orthogonal detector subjects a received signal to orthogonal detection by using the local oscillation signal so as to output an I-phase baseband signal and a Q-phase baseband signal. A first HPF and a second HPF reduce a direct current component of each of the I-phase baseband signal and the Q-phase baseband signal. A demodulator demodulates the I-phase baseband signal and the Q-phase baseband signal output from the first HPF and the second HPF. A distribution detector detects an unevenness in a distribution of the I-phase baseband signal and the Q-phase baseband signal with the reduced direct current component. When the distribution detector detects an unevenness in the distribution, the distribution detector changes a status of the first HPF and the second HPF.

The present disclosure relates to a communication method and system for converging a 5.sup.th-Generation (5G) communication system for supporting higher data rates beyond a 4.sup.th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. There may be provided a method for receiving a downlink by a UE that uses narrowband communication and a UE for performing the same, the method comprising the steps of: setting one subcarrier, among narrowband frequency resources assigned to the UE, as a narrowband direct current (DC) subcarrier; receiving a signal regarding the narrowband frequency resources from an eNB; and decoding the received signal on the basis of the narrowband DC subcarrier that has been set.