Abstract: An apparatus and method for estimating a decision boundary in symbol units in a mobile communication system. The method for estimating a decision boundary of reception symbols in a receiver of a mobile communication system includes the step of calculating a preliminary decision boundary for every symbol entered a decision boundary estimator; and reflecting the preliminary decision boundary calculated for every symbol in a previous symbol's decision boundary having been calculated in consideration of a channel environment until reaching the previous symbol, and calculating a new decision boundary for the entered symbol.

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: Provided is a method for measuring a neighbor cell signal in a portable terminal includes acquiring a minimum required quality level value and a threshold for an intra-frequency measurement from received system information; calculating a measured cell quality value after the acquiring step; and commencing a neighbor cell signal measurement for an intra-frequency cell reselection when a value acquired by subtracting the minimum required quality level value from the measured cell quality value is less than or equal to a value acquired by adding the threshold and a certain signal strength value over a certain time. In the neighbor cell signal measurement for the cell reselection, the unnecessary neighbor cell signal measurement can be avoided to reduce the power consumption and extend the battery lifetime.

Abstract: Apparatus and method are disclosed for selecting a transmit antenna diversity scheme according to a variation speed of a fading channel in a mobile communication system. A user equipment (UE) estimates a channel response of a pilot channel by receiving a pilot channel signal from a Node B; estimates a variation speed of a fading channel by using the estimated channel response and determining a transmit antenna diversity scheme suitable to the variation speed of the fading channel; and transmits feedback information including the determined transmit antenna diversity scheme to the Node B, so that the Node B can determine a transmit antenna diversity scheme for a channel signal to be transmitted to the UE based on the transmit antenna diversity scheme information included in the feedback information. In this way, the Node B adaptively applies a transmit antenna diversity according to a channel condition.

Abstract: In a mobile communication system, receivers measure channel characteristics using a received reference channel signal. The receivers determine a weight which has orthogonality with respect to each of a preset number of weight vectors in the mobile communication system and has the highest signal-to-interference-and-noise ratio, and feedback the weight and the corresponding signal-to-interference-and-noise ratio to the transmitter. The transmitter interprets the feedback information output from the receivers and determines receivers having feedback information which are orthogonal to each other and have the maximum throughput as an addition capacity when transmitted simultaneously, and determines weights based on the feedback information of the receivers having the maximum throughput. By applying the determined weights to the antennas using a well-known beam forming scheme, data can be transmitted to each of the determined receivers.

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 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 an apparatus and a method for reselecting a Public Land Mobile Network (PLMN) in a mobile communication terminal. The method includes requesting the updating of location registration to a target PLMN after storing current system information, determining whether a Subscriber Identify Module (SIM) card is valid when it fails to update the location registration, and resetting the SIM card to a previous state and then, reading the stored current system information to request the updating of location registration in the current PLMN when the SIM card is invalid.

Abstract: An apparatus for retransmitting data at a retransmission request from a receiver by a transmitter in a CDMA mobile communication system including a turbo encoder with a given coding rate and initially transmitting systematic bits and parity bits obtained by encoding the data by the turbo encoder using one modulation mode among a plurality of modulation modes. A controller determines a modulation mode to be used between the transmitter and the receiver in response to the retransmission request. A distributor distributes coded bits obtained by encoding the data at the coding rate into systematic bits and parity bits. A selector selects coded bits transmittable by the determined modulation mode among the systematic bits and the parity bits at the initial transmission, if the determined modulation mode is different from the modulation mode used at initial transmission. A modulator modulates the transmittable coded bits into modulated symbols according to the determined modulation mode.

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: A method and an apparatus for redistributing differentiated power for transmitting high speed packet data according to UEs in high speed packet data transport system. The method and apparatus redistribute powers, which have been already assigned in order to transmit the high speed packet data, thereby improving the performance of the system.

Abstract: Provided is an apparatus and method for preventing successive failures in a call connection in a mobile communication terminal. When a call connection is attempted, a cell with the highest RX power is selected among cells and an RRC Connection Request message is transmitted from the mobile terminal to a BS of the selected cell. It is determined whether the mobile terminal receives an RRC Connection Accept/Reject message from the BS. If the mobile terminal receives an RRC Connection Reject message from the BS of the selected cell, it is determined whether the selected cell is able to perform the RRC connection by detecting a Connection Reject message frequency that is the number of times of rejection of an RRC connection request for a predetermined period. If the selected cell is not able to perform the RRC connection, a neighboring cell is reselected and an RRC Connection Request message is transmitted to the reselected neighboring cell.

Abstract: Provided is an apparatus and method for transmitting/receiving an HS-SCCH in a wideband wireless communication system. In a method for transmitting control information in an HARQ wireless communication system, an ACK/NACK fed back from a receiver is monitored to determine if an ACK/NACK repetition factor needs to be adjusted. If the adjustment is needed, the ACK/NACK repetition factor is determined. Control information corresponding to the ACK/NACK repetition factor is transmitted to the receiver over a predetermined control channel. A Node B capable of directly detecting the uplink channel conditions, adjusts the ACK/NACK repetition factor and the adjusted ACK/NACK repetition factor is rapidly transmitted to a UE.

Abstract: An apparatus and method for assigning sub-carriers in an orthogonal frequency division multiplex (OFDM) system are disclosed. In the apparatus and method, data is transmitted through at least one transmit antenna. At least two sub-carriers in a predetermined frequency band are assigned to a user equipment (UE), for data transmission. A Node B groups sub-carriers available to the OFDM system into sub-carrier groups, each having at least two sub-carriers, transmits data to the UE on sub-carriers in the sub-carrier groups, selects at least one sub-carrier group for the UE based on channel condition information about each of the sub-carrier groups received from the UE, and assigns the selected sub-carrier group to the UE.

Abstract: An apparatus and method for improving turbo code performance in a communication system are provided. In the apparatus, a bit inserter inserts a predetermined number of bits into a transmission information bit stream, if the effective coding rate of a transmission packet is a predetermined coding rate. A turbo encoder turbo-encodes a bit stream received from the bit inserter and outputting code symbols. A rate matcher matches the code symbols to a predetermined size.

Abstract: In an apparatus for data transmission in a communication system, a turbo encoder encodes data bits to generate systematic bits and parity bits, and a rate matcher matches the systematic bits and parity bits. A first interleaver writes the rate-matched systematic bits on a row by row basis, and performs inter-column permutation. A second interleaver writes the rate-matched parity bits on a row-by-row basis, and performs inter-column permutation. A modulator alternatively collects the permutated bits on a column by column basis from the first and second interleavers, and maps collected bits from the first and second interleavers onto one modulation symbol, wherein a size of the first interleaver is equal to a size of the second interleaver.

Abstract: A transmitter simultaneously performs channel coding and rate matching in a CDMA mobile communication system. The transmitter encoders input bits into coded bits at a given mother code rate, and performs puncturing on the coded bits in order to match the number of coded bits to a predetermined code rate. Thereafter, the transmitter simultaneously performs rate matching for repeating or puncturing the coded bits in order to match the number of coded bits to the number of bits transmitted over a radio channel.

Abstract: A transmission/reception apparatus and method for performing packet retransmission considering a channel environment in a CDMA mobile communication system. Upon receiving a retransmission request from a receiver, the apparatus and method selects a modulation type to be used according to a condition of a transmission channel, and changes the previously used puncturing pattern in order to output the proper number of coded bits for the selected modulation type.

Abstract: Disclosed is a method for transmitting data comprised of bits with higher priority and bits with lower priority output from a coder, using a high-order modulator in which a bit stream comprised of at least 3 bits represents one symbol and includes a first bit part with higher reliability and a second bit part with lower reliability. The method comprises modulating the bits with higher priority and the bits with lower priority such that the bits with higher priority are mapped to the first bit part and the bits with lower priority are also mapped to the first bit part at initial transmission; and modulating the bits with higher priority and the bits with lower priority such that the bits with higher priority are mapped to the second bit part and the bits with lower priority are mapped to the first bit part at retransmission.