Abstract: A method for retransmitting coded bits by a transmitter in response to a retransmission request from a receiver in a mobile communication system which separates coded bits output from an encoder into coded bits with higher priority and coded bits with lower priority, and transmits from the transmitter to the receiver a stream of symbols obtained by symbol mapping the coded bits by a specific modulation technique. The method comprises determining orthogonal codes available for retransmission; separating the coded bits with higher priority and the coded bits with lower priority into a plurality of sub-packets with a given size, and selecting a part of the sub-packets or sub-packets to be repeatedly transmitted, depending on the determined number of available orthogonal codes; and transmitting a stream of symbols obtained by symbol-mapping coded bits of the selected sub-packets by the specific modulation technique, with the determined available orthogonal codes.

Abstract: An apparatus and a method for improving the performance of an error correction code in response to the influence of error propagation are disclosed.

Abstract: A de-rate matching method and apparatus in a High Speed Downlink Packet Access (HSDPA) system are provided.

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: An apparatus and method for transmitting control information in a mobile communication system are disclosed. The apparatus and method include selecting a pilot signal having different predetermined pilot patterns according to whether the data are received and the data contain an error, and inserting the selected pilot signal into a pilot field of a dedicated physical channel frame as control information and transmitting the dedicated physical channel frame.

Abstract: A method and apparatus for efficiently transmitting channel quality information on a radio channel in a mobile communication system are provided. The reporting cycle of channel quality information is changed adaptively according to time-varying characteristics associated with the Doppler frequency of a radio channel or the variation of the channel quality information. Therefore, the channel quality information is efficiently transmitted. Also, the decrease of unnecessary frequent information transmissions reduces an uplink interference power level and power consumption in user equipment (UE), as well.

Abstract: An apparatus and method for improving the performance of an error correction code against the effects of error waves in a Multi-Input Multi-Output (MIMO) communication system are provided. In a receiver of the MIMO communication system, a Minimum Mean Square Error (MMSE) receiver unit estimates transmitted signals from at least two paths using signals received at each of receive antennas, a signal deprocessor selects one of the estimated signals, stores the other estimated signal, assigns weighting values to the selected signal and a previous detected signal, combines the weighted signals, and detects transmitted data from the combined signal, a signal reproducer reproduces a transmitted signal from the detected transmitted data, and a subtractor updates the received signals by subtracting the reproduced transmitted signal from the received signals and provides them to the MMSE receiver unit.

Abstract: An apparatus and a method for transmitting control information in a mobile communication system are disclosed. In a mobile communication system including a transmitter for transmitting data and a receiver for receiving the data, when transmitting information regarding whether the data have been received, the receiver generates identifiers having different signs according to whether received data contain an error, adds the generated identifiers to a physical channel, and transmits the physical channel. The transmitter detects a sign corresponding to an existence or absence of an error from the information regarding whether or not the data have been received, detects transmission error for the data according to the detected sign, and determines whether the data are retransmitted according to a result of the detection.

Abstract: An apparatus and a method capable of effectively allocating sub-carriers for a plurality of users and transmitting the sub-carriers to users through multiple antennas in an orthogonal frequency division multiplexing (OFDMA) mobile communication system are provided. A sub-carrier allocation method reduces transmission power by taking a desired bit rate and power budget into consideration. The sub-carriers are optimally allocated to each antenna, so that peak to average power ratio (PARR) is reduced and Quality of Service (QoS) is improved. The apparatus and the method are adaptable for multi-users and obtain space diversity gain through multiple antennas.

Abstract: An apparatus and method for detecting the reception timing of a received signal in a mobile communication system are provided. Two time points having the same energy, earlier and later than the received signal, are detected. The energy ratio between other time points spaced from the two time points by the same interval is calculated and it is determined whether the energy ratio falls into a predetermined rage. If the energy ratio is within the range, the received signal is considered to have no effects from an interference signal or a neighboring signal.

Abstract: Disclosed are an apparatus and a method capable of preventing performance degradation during a channel decoding process. A bit interleaving is performed with respect to parity bits among coded bits output through a channel coding unit, thereby preventing a repetition period of the parity bits from matching a puncturing period for a rate matching. A bit de-interleaving is performed with respect to the parity bits during a channel decoding process, so that the parity bits have a repetition period identical to initial parity bits. Thus, the repetition period of the parity bits is not matched with the puncturing period for the rate matching, thereby preventing performance degradation during the channel decoding process.

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: 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: 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: 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: 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: 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 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: An apparatus and method for multiplexing/demultiplexing transport channels in an HSDPA (High Speed Downlink Packet Access) communication system. Upon generation of transport blocks to be transmitted to a UE (User Equipment), the transport blocks are concatenated to a transport block set. The transport block set is segmented into a plurality of code blocks according to the number of bits in the transport block set. The code blocks each are attached with CRC (Cyclic Redundancy Check) bits and mapped to transport channels.

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.