Samsung Electronics Co., Ltd.

Qualcomm Incorporated

Sungkyunkwan University

Hee-Jin Roh

Min-Goo Kim

Su-Jin Yoon

Sung-Jin Park

Hyun-Seok Oh

Eun-Jeong Yim

Hoon Jong Kang

Sung-soo Kim

Hyung-Jin Choi

Sang-Min Bae

Ji-Won Ha

Jong-Han Lim

Se-Bin Im

Jun-Kyu Kang

Hoon Chul Kang

Se-bin Im

Dong-Kyoon Cho

Chang-hyun Baik

Jeoung-Gil Lee

Dae-Hong Lee

Kyung-Hyun Paik

An apparatus and a method for mitigating interference between uplink signals of a user equipment in a mobile communication system are provided. The apparatus includes a frequency regulator for, when fast movement of a user equipment is confirmed, changing a transmit frequency by calculating a frequency offset compensation value which compensates for a frequency required for a transmit frequency band.

Apparatus and method for controlling frequency in mobile communication system

A correlation apparatus and method for frequency synchronization are provided. A frequency synchronization method of a receiver in a broadband wireless access communication system includes acquiring a highest correlation value by conducting a differential correlation of a variable interval between a received signal and a reference signal and performing a frequency synchronization according to the highest correlation value.

Correlation apparatus and method for frequency synchronization in broadband wireless access communication system

Disclosed is a channel estimation method and apparatus in an OFDM system. The method includes performing channel estimation at a pilot position of a received symbol, thereby calculating a first channel estimate, performing diagonal interpolation between the first channel estimate and a channel estimate for another pilot position that is different from the first pilot position, thereby calculating a second channel estimate for a data position, performing time interpolation between the second channel estimate and a channel estimate for another pilot position that is identical to the second pilot position, thereby calculating a third channel estimate for another data position, and performing frequency interpolation by using the channel estimates for the pilot positions and the second and third channel estimates, thereby calculating channel estimates for remaining data positions.

Channel estimation method and apparatus in orthogonal frequency division multiplexing system

Disclosed are a channel estimation method and a channel estimation apparatus, and a receiver using the same. The channel estimation apparatus provided in the receiver detects pilot signals from radio signals and estimates channels of the detected pilot signals. The channel estimation apparatus estimates channels corresponding to data by conducting linear interpolation, which allows for simultaneous interpolation in time and frequency axes, by use of information on the estimated pilot channels. Thus, the memory capacity required for the receiver can be reduced using channel estimation in which the simultaneous interpolation is conducted. Also, the performance of the receiver can be further improved in a wireless environment where the receiver moves at high speed.

Channel estimation method and apparatus using linear interpolation scheme in orthogonal frequency division multiplexing system and receiver using the same

An apparatus and method for recovering a carrier frequency of a received signal using a predefined symbol in an OFDM system is provided. A maximum value detector detects at least three values and their corresponding offsets in descending order among auto-correlation values calculated within a specific frequency offset range between a received signal and a predefined symbol. A frequency offset corrector compares a ratio of a first auto-correlation value to a second auto-correlation value with a predetermined first threshold, determines whether first and second frequency offsets corresponding to the first and second auto-correlation values are adjacent to each other if the ratio of the auto-correlation values is less than the first threshold, and determines an initial carrier frequency offset using a difference between the first frequency offset and a frequency offset correction value determined according to system, if the first and second frequency offsets are adjacent to each other and a ratio of the second auto-correlation value and a third auto-correlation value is greater than a predetermined second threshold.

Apparatus and method for recovering frequency in an orthogonal frequency division multiplexing system

An apparatus and method for carrier frequency synchronization in an Orthogonal Frequency Division Multiplexing (OFDM) system are provided for correcting an initial carrier frequency offset in the OFDM system. A metric generator for frequency estimation performs a first accumulation process for a value computed by multiplying a Phase Reference Symbol (PRS) generated from a reception stage by a Fast Fourier Transform (FFT) output signal for an OFDM symbol in a PRS position within a frame, acquires a differential symbol from a product of adjacent FFT output symbols, performs a second accumulation process for a real part extracted from the differential symbol, and outputs a metric value for the frequency estimation. A maximal value-related index generator compares metric values for initial frequency estimation within a predetermined frequency offset estimation range, and selects and outputs a maximal metric value as a frequency offset estimate.

Apparatus and method for carrier frequency synchronization in an OFDM system

A Phase Locked Loop (PLL) is provided for improving acquisition performance in an acquisition state, while preventing performance degradation in a steady state under a low SNR environment, during phase detection, a phase detecting method for the PLL, and a receiver using the same. The PLL determines a period to which an input signal belongs according to the input signal and a feedback signal, outputs an error signal corresponding to the input signal by using a formula (or algorithm) set for the determined period, oscillates a predetermined frequency signal according to the error signal, and feeds back the oscillated signal.

Phase locked loop, phase detecting method for the phase locked loop, and receiver using the same

A broadcasting receiving apparatus and method in a broadcasting system are provided. In a broadcasting receiver, a demodulator demodulates a received broadcasting signal, clips a soft metric value for the demodulated signal to a number of bits, and outputs the clipped soft metric value. A mapper maps the clipped soft metric value to an index value with a resolution inversely proportional to the quantization level of the soft metric value. A deinterleaver deinterleaves the index value and a demapper demaps the deinterleaved index value to a representative value being a soft metric value from a range of soft metric values mapped to the index value. A channel decoder decodes the representative value.

Apparatus and method for receiving broadcasting service in a broadcasting system

An apparatus and method for estimating and combining frequency errors in a mobile communication system. A controller divides data received from a main base station (BS) and control information received from a neighbor BS and controls allocation to fingers. A main automatic frequency control (AFC) loop is formed by estimating and combining frequency errors of the data received from the main BS. A sub AFC loop is formed by subtracting a corrected value of the main AFC loop after estimating and combining frequency errors of the control information received from the neighbor BS.

Apparatus and method for estimating and combining frequency errors in a mobile communication system

A method and apparatus for performing channel compensation and symbol demodulation using an estimated channel impulse response during coherent demodulation of a received Orthogonal Frequency Division Multiplexing (OFDM) signal are provided. In the apparatus, an FFT processor IFFT-processes a received signal. A channel compensator generates a channel-compensated signal by multiplying the FFT received signal by an estimated channel impulse response and calculates the power of the estimated channel impulse response. A symbol demodulator sets the power of the estimated channel impulse response as a reference point defining a minimum distance between signal points in a signal constellation, and decides soft metric values for channel decoding using the reference point and I-channel and Q-channel signal components of the channel-compensated signal. A decoder recovers information bits by decoding the soft metric values.

Method and apparatus for performing channel compensation and symbol demodulation for coherent demodulation in an OFDM system

Disclosed are an apparatus and a method for efficiently transmitting a broadcasting channel by means of cyclic delay diversity in an OFDM mobile communication system. The method comprises the steps of setting each transmitter to have different delay values, the transmitter providing a service to adjacent service areas, generating OFDM signals including the broadcasting data by said each transmitter, delaying the OFDM signals by means of the different delay values, and transmitting the delayed OFDM signals by means of each transmitting apparatus.

Apparatus and method for efficiently transmitting broadcasting channel utilizing cyclic delay diversity

An apparatus and a method are provided for improving reception reliability for control channels by detecting time division multiple (TDM) frames transmitted through the control channels in a TDM mobile communication system. The apparatus and method include receiving the frame through the forward control channel and performing a cyclic redundancy checking (CRC) with respect to the frame, thereby outputting a first error detection bit, measuring reception power for the frame, calculating a first path metric when decoding a channel of the frame, estimating a second path metric by using the first path metric and the reception power, and outputting a second error detection bit by comparing the second path metric with a predetermined threshold value, and creating and outputting a frame quality bit for detecting validity of the frame based on the first and second error detection bits.

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Suwon-si, South Korea

Hee-Jin Roh