Abstract: Disclosed is a base station that performs coordinated communication with a plurality of remote radio heads (RRHs), including: a communication unit receiving source signals from the plurality of remote radio heads; a measurement unit measuring signal intensities and delay times of the respective source signals; a selection unit selecting remote radio heads that will perform the coordinated communication among the plurality of remote radio heads based on the signal intensities and the delay times; and a demodulation unit demodulating source signals received from the selected remote radio heads.

Abstract: Provided are a preamble transmission device of a multi-mode supporting base station and a preamble detecting device of a multi-mode supporting user terminal. Selecting of the preamble signal is driven by the user terminal capable of supporting multi-modes, which contributes to smooth services from a user's viewpoint, and to effective use of the limited radio resources from an operator's viewpoint.

Abstract: A method of compensating for reverse current leakage in an active rectifier may include advancing an output of a comparator by a predetermined period of time by applying a predetermined offset voltage to a reference voltage input to the comparator, and activating a switch based on the output of the comparator. The method may also include deactivating the switch when a predetermined time delay elapses from a point in time at which the switch was activated.

Abstract: The present invention relates to a PFC control circuit, an active PFC circuit, and a PFC control method. According to an embodiment of the present invention, a PFC control circuit including: an inductor current sensing unit for sensing an inductor current of a PFC circuit; an output voltage feedback unit for outputting a feedback output signal; a sensing and feedback signal application unit for outputting a sensing voltage signal during switching duty on of the PFC circuit and adding the feedback output signal to the sensing voltage signal to output the added signal during switching duty off of the PFC circuit; and a PFC control unit for generating a comparison signal and generating a duty control signal from the comparison signal and a first reference signal to make variations due to an internal offset be removed or reduced is provided.

Abstract: The present invention relates to an IC circuit. In an embodiment, an IC circuit includes: an RT terminal connected to an external; a current mirroring unit conducting a channel current between internal voltage power and the RT terminal and generating an internal reference current mirrored with the channel current; a negative feedback unit receiving the internal reference current, equalizing voltages of an RT terminal connection terminal and an internal reference current output terminal of the current mirroring unit to make the internal reference current constant, and providing the internal reference current inside the IC circuit; and an IC state indicating unit having a transistor, which operates complementarily with the current mirroring unit, connected between the RT terminal and a ground and providing the state of an IC or a system to the RT terminal by being linked with the complementary operation of the current mirroring unit.

Abstract: There is provided a power factor correction circuit including: a power conversion circuit unit controlling an inductor current according to a switching signal applied to a main switch to convert an external input voltage into an output voltage having a predetermined range; an imbalance detection circuit outputting an imbalance state signal when the external input voltage is in an unbalanced state by using the inductor current; and a soft start circuit unit performing soft starting by adjusting the switching signal when the imbalance state signal is output by the imbalance detection circuit unit.

Abstract: Provided are a preamble transmission device of a multi-mode supporting base station and a preamble detecting device of a multi-mode supporting user terminal. Selecting of the preamble signal is driven by the user terminal capable of supporting multi-modes, which contributes to smooth services from a user's viewpoint, and to effective use of the limited radio resources from an operator's viewpoint.

Abstract: There are provided a phase shift circuit and a power factor correction circuit including the same. The phase shift circuit includes a switching circuit unit charging power in or discharging power from a capacitor through a plurality of switching devices and comparing a voltage of the capacitor with a predetermined reference voltage, and a clock generating unit generating a reference clock signal based on an output of the switching circuit unit, wherein the switching circuit unit turns the plurality of switching devices on or off, based on currents from inductors respectively included in a main circuit and a sub-circuit of a power factor correction circuit to determine a polarity of the voltage of the capacitor.

Abstract: An apparatus and a method for charge control are provided. The apparatus for charge control may include an integrated direct current-to-direct current (DC/DC) converter configured to step up an output voltage level of a load to be greater than or equal to a supply voltage level set in a power amplifier, and the power amplifier configured to convert a direct current (DC) voltage stepped up by the integrated DC/DC converter into an alternating current (AC) voltage based on a resonant frequency, and to amplify the converted AC voltage. The apparatus for charge control may include a rectification unit configured to convert an AC power received wirelessly into a DC power; and a DC/DC converter configured to step down a voltage level of the DC power to a voltage level required by a load in the receiving mode.

Abstract: An apparatus and a method for wireless power reception are provided. A wireless power receiver includes a receiving unit configured to wirelessly receive a power. The wireless power receiver further includes a power consuming unit configured to consume the power, until a voltage applied to a load reaches a predetermined value, so that an amount of a power transferred from the receiving unit to the load is less than or equal to an initial accommodation power amount of the load.

Abstract: A multiple input multiple output (MIMO) iterative receiver detects a soft log likelihood ratio value from a signal outputted from a transmitter and decodes the detected soft log likelihood ratio value in order to extract a hard value and a soft value from the detected soft log likelihood ratio value. After whether or not a CRC of the hard value is acknowledged is determined, a CRC of a data burst is determined or iteration of signal demodulation of the MIMO iterative receiver is determined by feeding back the soft value or a CRC of data is performed assembling signals of the burst unit in accordance with the determination result.

Abstract: The present invention relates to an apparatus and method for variable fast Fourier transform. According to an embodiment of the present invention, two n-point fast Fourier transform (FFT) processors are used to generate two n-point FFT output data or one 2n-point FFT output data. The one 2n-point input data is alternately input to the two n-point FFT processors. Each of the two n-point FFT processors selects a twiddle factor for the n-point input data or the 2n-point input data and performs fast Fourier transform. A butterfly operation is performed on signals obtained by performing fast Fourier transform on the 2n-point input data signal, and the processed signals are aligned in an output order. According to this structure, it is possible to realize a fast Fourier transform hardware engine that selectively performs multi-frequency allocation in a base station system that supports the multi-frequency allocation.

Abstract: In a method for detecting a signal in a multi-input multi-output wireless communication system that receives signals transmitted through a plurality of transmission antennas by using a plurality of reception antennas, a detection order for detecting the transmission signals received through the reception antennas is determined on the basis of a cofactor determinant of components constituting a channel matrix representing characteristics of channels between the transmission antennas and the reception antennas. In addition, the transmission signal is detected from the signals received through the reception antennas in accordance with the determined detection order.

Abstract: A relaxation oscillator includes a ramp wave generator configured to generate a ramp wave by complementary first capacitor module charged and discharged according to a first switching signal and second capacitor module charged and discharged according to a second switching signal, a negative feedback circuit unit configured to generate a compensation voltage for compensating an error between the ramp wave and a reference voltage through a feedback of the ramp wave, and a switching signal generator configured to generate the first switching signal and the second switching signal from the compensation voltage and the ramp wave, including a peak voltage storage unit configured to store a peak voltage of the ramp wave that is controlled to be equal to the reference voltage based on the compensation voltage and a peak voltage transfer unit configured to transfer the peak voltage of the ramp wave to the negative feedback unit.

Abstract: Provided are a direct current/direct current (DC/DC) converter and a wireless power receiver including the DC/DC converter. In one embodiment, a direct current-direct current (DC/DC) converter for use in a wireless power receiver, the DC/DC converter may include: a voltage converting unit configured to convert, DC voltage, to a predetermined DC voltage; a turn-on switch configured to control current flow of the DC voltage through the voltage converting unit; and a switching controller configured to: detect an amount of current of the voltage converting unit based on a first turn-on period of the turn-on switch, set a second turn-on period of the turn-on switch based on the detected amount of current, and control the turn-on switch based on the second turn-on period.

Abstract: The present invention relates to a fast uplink ranging system and method in a mobile communication system. According to the present invention, a fast uplink ranging system transmits two pairs of ranging codes having the same value at locations spaced by half of FFT pointers. The fast uplink ranging system calculates a correlation value using the received two pairs of ranging codes. An order in which complex exponential twiddle factors for removing complex exponential terms corresponding to a time delay are searched is determined using the correlation value. Therefore, it is possible to reduce a time required for searching a timing error of a terminal using non-periodic symmetry of complex exponential twiddle factors corresponding to the timing error, compared with a known method of searching a complex exponential twiddle factor.

Abstract: There is provided relaxation oscillator. The relaxation oscillator includes: a ramp wave generator generating ramp waves by a complementary operation between a first capacitor module charged and discharged according to a first switching signal and a second capacitor module charged and discharged according to a second switching signal; a negative feedback circuit unit generating a compensation voltage for compensating errors with reference voltage by being fedback with the ramp waves; and a switching signal generator generating the first switching signal controlling the charging and discharging of the first capacitor module and the second switching signal controlling the charging and discharging of the second capacitor module from the compensation voltage and the ramp waves. As a result, the present invention can generate ramp waves having a stable frequency while preventing a frequency from being changed due to a delay or an offset of the comparator.

Abstract: An active rectifier and a wireless power receiver including the active rectifier are provided. According to an aspect, an active rectifier may include: a first loop configured to provide voltage when the phase of an input signal is positive; and a second loop configured to provide voltage when the phase of the input signal is negative, wherein the first loop and the second loop include a delay locked loop configured to compensate for reverse current leakage due to a delay of a switch included therein.

Abstract: A multiple input multiple output (MIMO) iterative receiver detects a soft log likelihood ratio value from a signal outputted from a transmitter and decodes the detected soft log likelihood ratio value in order to extract a hard value and a soft value from the detected soft log likelihood ratio value. After whether or not a CRC of the hard value is acknowledged is determined, a CRC of a data burst is determined or iteration of signal demodulation of the MIMO iterative receiver is determined by feeding back the soft value or a CRC of data is performed assembling signals of the burst unit in accordance with the determination result.

Abstract: In a method for detecting a signal in a multi-input multi-output wireless communication system that receives signals transmitted through a plurality of transmission antennas by using a plurality of reception antennas, a detection order for detecting the transmission signals received through the reception antennas is determined on the basis of a cofactor determinant of components constituting a channel matrix representing characteristics of channels between the transmission antennas and the reception antennas. In addition, the transmission signal is detected from the signals received through the reception antennas in accordance with the determined detection order.