Abstract: Provided is a scheduling apparatus and method for allocating resources to individual users in a multiantenna system. The method includes determining a ratio of time slots to be allocated according to a ratio desired by each of the terminals in every specific time slot interval, calculating a channel capacity average and a standard deviation for each terminal according to channel capacity reported from each terminal for a specific time, and determining, based on the determined ratio of time slots, a terminal to which a specific time slot is to be allocated according to the channel capacity average and the standard deviation, calculated for each terminal, and the last reported channel capacity.

Abstract: Disclosed is a differential space-time block coding apparatus with a high transmission rate in a wireless communication system employing multiple transmit antennas and a method thereof. The differential space-time block coding method includes the steps of, when elements of a transmission matrix B43v are transmitted in a predetermined block (a vth block) through a predetermined transmit antenna at a predetermined time, modulating a symbol Sv of inputted binary data to a symbol Sv+1, creating a matrix S44v+1 in a block (a (v+1)th block) following the predetermined block by substituting the modulated symbol for the matrix P44, and then, in order to perform a differential encoding function, multiplying the matrix B43v by the matrix S44v+1 so as to calculate a new matrix B43v+1 to be transmitted in the (v+1)th block.

Abstract: In an orthogonal frequency division multiplexing (OFDM) communication system using multiple transmit antennas, a first base sequence with a first length is segmented into a first number of second sequences to which different time offsets are applied. Subsequences of a first preamble sequence corresponding to the number of second sequences are generated. A second base sequence with a second length is segmented into a second number of third sequences to which different time offsets are applied. Subsequences of a second preamble sequence corresponding to the number of third sequences are generated. A subsequence is selected from the subsequences of the first preamble sequence and is transmitted through a transmit antenna in a first time interval. A third preset number of subsequences are selected from the subsequences of the second preamble sequence, and are mapped and transmitted to the transmit antennas in a second time interval.

Abstract: A mobile communication system includes M transmission antennas, P encoders for receiving P information bit streams and encoding the received information bit streams with a space-time trellis code (STTC), and M modulators for modulating information bit streams output from the P encoders in a predetermined modulation scheme and outputting modulation symbol streams. A sequence used for channel estimation is generated, and the sequence is transmitted in substitute for at least one modulation symbol in a predetermined position through the M transmission antennas, for each of the modulation symbol streams output from the M modulators.

Abstract: Disclosed is a method for deciding a signal detection order in a mobile communication system that supports an adaptive modulation technology. The detection order that maximizes a channel, in which a product of the minimum symbol distance for each modulation rate and the effective SINR becomes minimum, maximum is selected by obtaining the effective SINR and performing a bit allocation with respect to the detection orders of each detection order, and thus an average error probability can be minimized. In the case in which the number of antennas is increased, the detection orders of all the possible cases are not considered, but the detection order that maximizes the channel, in which the product of the minimum symbol distance for each modulation rate and the effective SINR becomes minimum, is selected with respect to a forward ordering and a reverse ordering.

Abstract: A transmitter and a receiver are disclosed herein that support transmit antenna diversity using space-time block coding in a wireless communication system. The transmitter produces symbol combinations containing, as their elements, input symbols, the inversions and conjugates of the symbols, and symbols obtained by rotating the phases of the symbols once, forms a matrix having symbols in at least two columns orthogonal to each other with the symbol combinations, and transmits the matrix. The receiver detects symbols that minimize maximum likelihood (ML) decoding metrics over all possible symbols using channel gains from transmit antennas to a receive antenna. Also, the receiver selects candidate symbols among all possible symbols according to the characteristics of transmitted modulation symbols and detects symbols that minimize the ML decoding metrics.

Abstract: A mobile communication system includes at least three transmission antennas of first to third transmission antennas, and uses an overlapped antenna scheme for grouping the first and second transmission antennas into a first transmission antenna group and grouping the second and third transmission antennas into a second transmission antenna group. First and second modulators modulate L information bit streams to be transmitted through the first transmission antenna group and output first and second modulation symbol streams. Third and fourth modulators modulate L other information bit streams to be transmitted through the second transmission antenna group and output third and fourth symbol streams. First to fourth puncturers puncture at least one modulation symbol in a predetermined position among the first to fourth modulation symbol streams.

Abstract: Disclosed is a method for configuring transmission antenna groups in a mobile communication system with multiple transmission antennas and multiple reception antennas. The method includes the steps of: receiving a first matrix having a size of ‘Nt×Nt’, which corresponds to Nt number of transmission antennas, fedback from the mobile terminal, generating combinations of sub-matrixes of the first matrix corresponding to Nr number of reception antennas, and calculating sums of maximum eigenvalues; determining combinations of the sub-matrixes having a maximum value from among the calculated sums of eigenvalues to be transmission antenna groups for the Nt number of transmission antennas; and transmitting different relevant symbols from each other through the transmission antenna groups.

Abstract: A mobile communication system includes M transmission antennas, P encoders for receiving P information bit streams and encoding the received information bit streams with a space-time trellis code (STTC), and M modulators for modulating information bit streams output from the P encoders in a predetermined modulation scheme and outputting modulation symbol streams. A sequence used for channel estimation is generated, and the sequence is transmitted in substitute for at least one modulation symbol in a predetermined position through the M transmission antennas, for each of the modulation symbol streams output from the M modulators.

Abstract: Disclosed herein is a scheduling method and apparatus based on eigen values robust against spatial correlation in a mobile communication system supporting multiple users by use of multiple transmit/receive antennas. A user terminal estimates channel characteristics from the transmit antennas to the user terminal, decomposes the estimated channel characteristics into receive channel characteristics and transmit channel characteristics, and feeds back a transmit principal eigen vector to the base station (BS). The BS selects a predetermined number of user terminals having the least correlation using the feedback principal eigen vectors from a plurality of user terminals, constructs a user precoding matrix by combining the principal eigen vectors of the selected user terminals, multiplies data streams for the selected user terminals by the user precoding matrix and transmits the multiplied data to the selected user terminals.

Abstract: An apparatus and method for full-diversity, full-rate space-time block coding in a transmitter using two Tx antennas are provided. An input symbol sequence is STBC-encoded in a predetermined method and transmitted through the two Tx antennas.

Abstract: A mobile communication system includes at least three transmission antennas of first to third transmission antennas, and uses an overlapped antenna scheme for grouping the first and second transmission antennas into a first transmission antenna group and grouping the second and third transmission antennas into a second transmission antenna group. First and second modulators modulate L information bit streams to be transmitted through the first transmission antenna group and output first and second modulation symbol streams. Third and fourth modulators modulate L other information bit streams to be transmitted through the second transmission antenna group and output third and fourth symbol streams. First to fourth puncturers puncture at least one modulation symbol in a predetermined position among the first to fourth modulation symbol streams.

Abstract: An STFBC coding apparatus for a transmitter with four Tx antennas is provided. In the transmitter, an encoder generates a code symbol vector by encoding an input symbol sequence in a predetermined coding method. A grouping block permutes the elements of the code symbol vector by multiplying the code symbol vector by a permutation antenna grouping pattern selected among predetermined permutation antenna grouping patterns according to a predetermined order and outputs the permuted code symbol vector as a grouping symbol vector. OFDM (Orthogonal Frequency Division Multiplexing) modulators OFDM modulate the grouping symbol vectors and transmit OFDM modulated symbols through the four transmit antennas.

Abstract: A coding technique for achieving a maximum diversity gain in a wireless communication system having a transmitter for transmitting data on a fading channel through a plurality of transmit antennas and a receiver for receiving the data through a plurality of receive antennas. In the coding technique, P mth-order sub-rotated vectors {right arrow over (r)}i are generated by constellation-rotating an Lth-order input vector {right arrow over (x)} including a plurality of input symbols modulated in at least one modulation scheme. m pth-order sub-vectors {right arrow over (u)}i are generated using the sub-rotated vectors {right arrow over (r)}i. Codeword matrices Ai({right arrow over (u)}i) are generated by performing orthogonal space-time block coding on the sub-vectors {right arrow over (u)}i and then transmitted through the transmit antennas.

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 and apparatus for a distributed network system where a cognitive radio (CR) technology is used. A communication method of a distributed network system where the CR technology is used includes transmitting adjacent channel information, from at least one first neighbor node adjacent to a source node, first adjacent channel information of the at least one first neighbor node using a pulse signal according to a request of the source node; by transmitting, from at least one second neighbor node adjacent to a destination node, second adjacent channel information of the at least one second neighbor node to the destination node using a pulse signal according to a request of the destination node; and exchanging data between the source node and the destination node using a channel that is not currently used, according to the transmitted adjacent channel information.

Abstract: Aspects of the present invention relate to a communication method and apparatus in a cognitive radio (CR) environment, the method including: receiving an uplink signal that is repeatedly transmitted via at least one candidate channel that is not being used; determining whether the receiving of the uplink signal is due to an existence of an incumbent user using a CR channel of the target cell; and changing the CR channel of the target cell when the receiving of the uplink signal is due to the existence of the incumbent user using the CR channel of the target cell.

Abstract: A method and apparatus of controlling a transmission power of a cognitive radio (CR) environment, the method including: sensing an incumbent user that uses a same channel as the CR environment; detecting signal quality information of the sensed incumbent user; calculating, using the detected signal quality information, a maximum transmission power value that corresponds to a maximum transmission power that may be transmitted by a CR base station in the CR environment; and controlling a communication of the CR environment to be performed within the calculated maximum transmission power value.

Abstract: A communication method and apparatus of a cognitive radio (CR) environment using a relaying system while not interfering with a communication system having a priority right to use a frequency band, the communication method including: listening to fundamental channel (FCH) information and/or downlink/uplink (DL/UL) map information of a frame transmitted in the relaying system; obtaining a transmission signal of the relaying system using the FCH information and/or the DL/UL map information; orthogonally encoding data to be transmitted in the CR environment based on the obtained transmission signal; and transmitting the orthogonally encoded data via a determined channel that is used in the relaying system. Accordingly, aspects of the present invention can retrieve radio resources unused in the CR environment more easily.

Abstract: A cooperative diversity method and apparatus that can minimize interference and maximize an efficiency of a transmission channel between terminals of a cooperative diversity pair, the method including: determining a pair of terminals to be a cooperative diversity pair according to a spectrum sensing result of a cognitive radio (CR); selecting a subchannel through which data is exchanged between the pair of terminals; and transmitting the data between the pair of terminals through the selected subchannel.