Abstract: A channel estimation method and apparatus using a self-tracking algorithm is provided for improving channel estimation accuracy. The channel estimation apparatus of a mobile terminal includes a receiver for converting a received radio signal into a baseband signal, a match filter for converting the baseband signal into a digital signal including at least two samples, a channel estimator for buffering the samples, for analyzing multipath signals to predict a maximum power position and multipath energy, and for estimating a channel by selecting a multi-tap at the maximum power position through a slew control, an equalization controller for calculating an equalization tap gain using the multi-tap selected by the channel estimator, and an equalizer for compensating for distortion in the samples output by the channel estimator using the equalization tap gain calculated by the equalization controller.

Abstract: A control channel element detection method and apparatus is provided for detecting the Control Channel Elements (CCEs) carrying control information for a mobile station using a Channel Quality Indicator (CQI). A CCE detection method includes searching a current subframe for CCEs, and locating the CCEs carrying control information for the mobile station by decoding the current subframe with variable code rates. Searching for the CCEs includes searching the current subframe for the CCEs carrying the control information for the mobile station while changing a size type of the CCEs according to a result of a comparison between a CQI of the current subframe and a CQI of a previous subframe.

Abstract: An apparatus and method for reducing power consumption of a receiver of a mobile communication system are provided. The apparatus includes an adaptive multi-tap segment channel estimator for determining a segment size according to a delay spread value for each channel tap, for determining a channel estimation frequency by determining a sum of segment block energy, and for allocating each segment to the channel estimator.

Abstract: A method for retransmitting coded bits by a transmitter in response to a retransmission request from a receiver in a mobile communication system. The method comprises determining a modulation technique to be used at retransmission as a modulation technique having a lower modulation order than a modulation technique used at initial transmission; determining a puncturing pattern according to an HARQ (Hybrid Automatic Repeat Request) type, and selecting as many coded bits as the number of coded bits that can be symbol-mapped by the determined modulation technique, among the coded bits punctured by the determined puncturing pattern; and symbol-mapping the selected coded bits by the determined modulation technique, and transmitting the symbol-mapped coded bits to the receiver.

Abstract: A method for retransmitting coded bits by a transmitter in response to a retransmission request from a receiver in a mobile communication system. The method comprises determining a modulation technique to be used at retransmission as a modulation technique having a lower modulation order than a modulation technique used at initial transmission; determining a puncturing pattern according to an HARQ (Hybrid Automatic Repeat Request) type, and selecting as many coded bits as the number of coded bits that can be symbol-mapped by the determined modulation technique, among the coded bits punctured by the determined puncturing pattern; and symbol-mapping the selected coded bits by the determined modulation technique, and transmitting the symbol-mapped coded bits to the receiver.

Abstract: A method and apparatus for estimating a Doppler frequency in a mobile terminal are provided. The method includes calculating two autocorrelation values for intervals of at least one sample from a channel estimation tap with a maximum power, and estimating a maximum Doppler frequency using the two autocorrelation values. The two autocorrelation values are autocorrelation values for intervals of different numbers of samples.

Abstract: An equalizer based receiver operation method and apparatus in a mobile communication system are provided. The method includes estimating a channel for a multi path receive signal, analyzing a delay profile of a multi path channel, and selecting a tap position from a plurality of tap positions of an equalizer depending on the analyzed delay profile.

Abstract: A transmitting/receiving apparatus and method for packet retransmission in a mobile communication system. Upon request for a retransmission from a receiver, a transmitter inverts initially transmitted coded bits if the retransmission is odd-numbered for the same data, modulates the inverted bits, and transmits the modulated bits to the receiver. Then the receiver recovers the coded bits by demodulation. If the coded bits are retransmitted an odd number of times, the receiver decodes the coded bits after inversion. Thus the error probabilities of initial transmission bits and retransmission bits are averaged in effect and decoding performance is improved.

Abstract: An apparatus and method for receiving a multipath signal in a wireless communication system are provided. The apparatus includes a sample buffer, a buffer index controller, a finger, and a Deskewer buffer and combiner. The sample buffer stores sample data corresponding to a defined number of chips among reception data converted into digital signals. The buffer index controller controls a position of the sample buffer to store the converted data and a position of the sample buffer to output data. The finger receives sample data from a specific position of the sample buffer and demodulates each multipath signal. The Deskewer buffer and combiner eliminates a temporal retard of each demodulated multipath signal and combines the multipath signals.

Abstract: Disclosed is a data transmission/reception apparatus and method for minimizing decoding errors during high-speed packet transmission in a CDMA mobile communication system. When retransmitting data in the Hybrid Automatic Repeat Request (“H-ARQ”) technique, the data transmission/reception apparatus and method performs symbol mapping on coded bits to be retransmitted by allocating different reliabilities to the coded bits according to the number of retransmissions, thus resulting in an improvement of system performance.

Abstract: An apparatus and method for transmitting/receiving data using a multiple antenna scheme in a mobile communication system are provided. First and second code symbol sequences are generated by encoding a data symbol sequence for transmission in a predetermined encoding method. Transmission of the two code symbol sequences through the first and second transmit antennas is controlled such that if the data symbol sequence is initially transmitted, the first code symbol sequence is transmitted through the first transmit antenna and the second code symbol sequence is transmitted through the second transmit antenna and, if the data symbol sequence is retransmitted, the first code symbol sequence is transmitted through the second transmit antenna and the second code symbol sequence is transmitted through the first transmit antenna.

Abstract: An apparatus and method for transmitting/receiving an HS-SCCH in an HSDPA communication system including an HS-DSCH shared among a plurality of UEs and spread with a plurality of channelization codes, and the HS-SCCH for transmitting control information related with the HS-DSCH to enable the UEs to receive the shared channel. In the HS-SCCH transmitting apparatus, the control information is prioritized according to its processing urgency degree. High-priority control information and low-priority control information are generated and encoded in different encoding methods. Then the high-priority control information and the low-priority control information are multiplexed to a control channel signal such that the high-priority control information precedes the low-priority control information.

Abstract: A bit scrambling method and apparatus for packet transmission/reception in a wireless communication system are provided. A transmitter performs bit scrambling before CRC attachment and a receiver performs bit descrambling after a CRC check. This enables termination of iterative decoding at a turbo decoder according to the CRC check. Hence, power consumption is reduced and throughput is increased at a receiver.

Abstract: A method for modulating a symbol in a transmitter of an Orthogonal Frequency Division Multiplexing (OFDM) system. The symbol modulation method includes multiplying an input stream of an Inverse Fast Fourier Transform (IFFT) unit by a Twiddling factor for circular-shifting the input stream of the IFFT unit by a Cyclic Prefix (CP) length; performing IFFT on the input stream of the IFFT unit, which is multiplied by the Twiddling factor; buffering data corresponding to the CP length beginning from a front of an output stream of the IFFT unit; and generating an OFDM symbol by forward-copying the buffered data to a back of the output stream of the IFFT unit.

Abstract: Disclosed is an adaptive channel estimator for improving a performance of a general channel estimator in a mobile communication system, and a method for controlling the same. The adaptive channel estimator further detects a noise level of a channel and a channel speed, and implements an optimum noise elimination filter on the basis of the detected noise level and channel speed. A comparison between mapping degrees predetermined by the detected noise level and channel speed allows an optimum noise elimination filter to be implemented, If such a channel estimator is implemented, then optimum packet data transmission is available for not only a low-speed channel but also a high-speed channel. A channel compensation caused by a difference between a spreading factor (SF) of a pilot channel and a spreading factor (SF) of a data channel can be compensated on the condition that a slope compensator executed by a SF ratio is controlled by a filter coefficient controller.

Abstract: A transmitting/receiving apparatus and method for packet retransmission in a mobile communication system. Upon request for a retransmission from a receiver, a transmitter generates first coded bits by inverting initially transmitted coded bits, generates second coded bits by separating the initially transmitted coded bits into a first bit group having a relatively high priority and a second bit group having a relatively low priority and exchanging the first bit group with the second bit group, and generates third coded bits by inverting the exchanged coded bits. The transmitter selects one of the first coded bits, the second coded bits according to the sequence number of a retransmission request received from the receiver, and the third coded bits and maps the selected coded bits to modulation symbols. The transmitter then transmits the modulation symbols to the receiver.

Abstract: A method and system of retransmitting uplink packet data from a user equipment (UE) in a handover region to Node Bs. The UE transmits packet data to the Node Bs on an enhanced uplink dedicated transport channel (EUDCH). The Node Bs transmit to the UE first response fields indicating whether the Node Bs have received good packet data or bad packet data, and second response fields that the Node Bs received from an RNC indicating whether a radio network controller (RNC) has received good packet data or bad packet data. The UE then detects the first and second response fields and retransmits the uplink packet data according to the values of the response fields in the UE.

Abstract: A data transmitting/receiving apparatus and method for improving the reliability of data bits in a CDMA mobile communication system. High-priority bits are mapped to a high-reliability bit position and low-priority bits, to a low-reliability bit position in symbols. Thus system performance is improved at a transmission.

Abstract: An apparatus and method for detecting a power ratio between a traffic channel and a pilot channel in a mobile communication system. The apparatus is operable to generate a second signal by performing channel estimation using a second channel signal, and generate a first signal by channel-compensating the first channel signal using the second signal. The apparatus is further operable to generate absolute values of symbols constituting the first signal, select absolute values in a predetermined length after sorting the absolute values in magnitude order, calculate an average value of the selected absolute values, calculate a square of an absolute value of the second signal, and generate the power ratio using a ratio of the average value to the square of the absolute value of the second signal.

Abstract: Provided are a decoder and decoding method wherein decoding is performed in consideration of input message characteristics. The decoder includes a fixed information checking unit for checking whether input data corresponds to fixed information; and a Branch Metric Calculation (BMC) unit for allowing the fixed information checking unit to check whether the input data corresponds to the fixed information upon receiving the input data, and if the input data corresponds to the fixed information, for computing branch metrics for a path by the use of the fixed information. Accordingly, error correction is improved.