Abstract: Disclosed is a method for estimating a frequency offset in a mobile communication system that divides a predetermined frequency band by a time division scheme to transmit data signals or divides an entire frequency band into a plurality of sub-frequency bands to transmit the data signals. The method includes the steps of modeling a fast fading channel by one of a linear equation and a polynomial equation; and applying the model to a variable for the channel after performing the modeling and estimating the channel and the frequency offset based on a joint maximum likelihood using a training sequence.

Abstract: In a method for feeding back combination information of transmitted signals in a multiple-input multiple-output (MIMO) system using a multiple space-time block coding technique, mean square error values are computed in relation to the combination information pieces of the transmitted signals. An index of a combination having a minimum mean square error value from among the mean square error values is fed back.

Abstract: A method of transmitting a signal by using an Adaptive Modulation and Coding scheme in a Frequency Hopping-Orthogonal Frequency Division Multiplexing Access communication system capable of dividing total frequency bands into a plurality of sub-carrier bands and including a plurality of sub-channels, which are sets of predetermined sub-carrier bands, and a plurality of cells. The method includes the steps of allocating a predetermined number of sub-channels as AMC sub-channels per each cell matching with predetermined conditions in order to apply the AMC scheme to the AMC sub-channels, and allocating remaining sub-channels except for the AMC sub-channels as FH-OFDMA sub-channels in order to apply an FH-OFDMA scheme to the FH-OFDMA sub-channels.

Abstract: A resource allocation method in a multiuser-multiple-input multiple-output/orthogonal frequency division multiple access (MIMO/OFDMA) system. In the multiuser-MIMO/OFDMA system feedback information is received from terminals. A channel gain and a transmission rate for each user are determined using the feedback information. An average channel gain for each user is computed according to the channel gain. The average number of bits for each user is determined according to the average channel gain. The number of subchannels for each user is computed according to the average number of bits for each user. At least one subchannel is allocated to each user according to the number of subchannels for each user. A modulation scheme for each of the at least one subchannel is determined. The resource allocation method adaptively allocates subchannels and bits according to channel environment, thereby considerably improving frequency use efficiency as well as a power gain.

Abstract: A pilot designing method in an uplink OFDMA system is provided. In the uplink OFDMA system, communications are carried out in a frame divided into time-frequency lattices, and each time-frequency lattice includes a plurality of data symbol periods and a plurality of pilot symbol periods intermittently arranged with respect to the data symbol periods. The frame is divided into a plurality of blocks. The blocks are allocated to the terminals. A predetermined allocated pilot time-frequency lattice is shared between adjacent terminals.

Abstract: An adaptive modulation scheme relating to an RA problem for maximizing the transmission rates of all users for maximum transmission rates in an OFDMA system including some users requiring to use services at fixed data rates. The scheme proposes introduction of an adaptive modulation using linear programming into an existing scheme for a system including a single kind of users, thereby enabling simultaneous execution of the adaptive modulation for all users in a system including two kinds of users. Further, the invention proposes another scheme of sequentially allocating subchannels to the users when the fixed transmission rate has a sufficiently small value, in order to reduce the complexity.

Abstract: A communication method in an FH-OFDM communication system having a plurality of BSs is provided. A predetermined number of pilot pattern groups are generated, each pilot pattern group having a predetermined number of different pilot patterns for pilot transmission. The pilot patterns in each of the pilot pattern groups are mapped to different FH sequence sets. The pilot patterns and FH sequence sets are assigned to the BSs so that MSs within the service areas of the BSs can identify the BSs.

Abstract: A transmission apparatus for DS/CDMA system with MIMO antenna system is disclosed. The apparatus includes a transmitter for transmitting data by applying different scramble code to each transmitting data through a plurality of the transmitting antennas and receiver for receiving transmitted data by obtaining diversity gain based on the maximum order of the diversity in order to effectively detect data. The present invention has excellent detection performance by receiving data with full order of diversity, which is multiple of the number of receiving antennas and the number of multipath, without complicated operation such as a decision feed equalizer.

Abstract: An adaptive interference suppression receiver for a DS/CDMA system includes: input signal generators outputting a part of received signals of receiver antennas that has a coding block's transfer code; adaptive filter blocks filtering a complex signal output from the input signal generators with a tab weight updated based on a constraint MMSE criterion and estimating phase and amplitude components of a specific user channel using the filtering output signal to generate a channel-estimated signal; a signal restorer combining the channel-estimated signal and the filtering output signal and restoring an original signal; a signal selector for selecting known training data signal or the restored signal; and error generators comparing the channel-estimated signal and the filtering output signal and calculating an error between the two signals.

Abstract: An optical recording medium for recording a predetermined subtitle code in a predetermined region in which contents are stored, and an apparatus and method to play the optical recording medium which are capable of displaying a subtitle on a screen when the contents are played. The method of playing an optical recording medium includes analyzing a stream that is read from the optical recording medium, and searching whether a predetermined subtitle code is recorded in a reserved region in a predetermined stream, storing the searched predetermined subtitle code and outputting the stored predetermined subtitle code with a command execution key, and signal-processing the predetermined subtitle code that is output with the command execution key, and displaying the signal-processed predetermined subtitle code on a screen of the played optical recording medium.

Abstract: An optical recording medium for recording a predetermined command code at a predetermined region of contents, an apparatus and method to play the optical recording medium, which executes a predetermined command when the contents are played so that the predetermined command is moved into contents at a predetermined portion of a screen. The method of playing an optical recording medium includes analyzing a signal that is read from the optical recording medium, and searching whether a predetermined command is recorded in a reserved region in a predetermined packet, storing the searched predetermined command and executing the stored predetermined command with a command execution key, and displaying the result of the command that is executed with the command execution key on a screen of the optical recording medium.

Abstract: An adaptive RAKE receiving apparatus is constrained with at least one constraint for use in a mobile communication system.