Abstract: Disclosed is a method for generating a space-time trellis code (STTC) for maximizing space-time diversity gain and coding gain in a mobile communication system including at least two transmission antennas and generating a second number of STTC codes with an information data bit stream upon receiving the information data bit stream comprised of a first number of bits.

Abstract: A method and apparatus for transmitting/receiving a differential space-time block code (STBC) by estimating only channel power in a wireless communication system using a plurality of transmission antennas. A receiver for receiving information symbols encoded by a differential STBC before and decoding the received information symbols collects a signal received at a reception antenna from a plurality of transmission antennas for one block duration; calculates a substitution signal by multiplying the received signal by a signal received for a previous block duration; estimates channel power for a channel from the plurality of transmission antennas to the reception antenna; normalizes the estimated channel power with a normalization value determined as a size of previously received symbols; and calculates information symbols by dividing the substitution signal by the normalized channel power.

Abstract: A apparatus and method for estimating a sequence of transmitted quadrature amplitude modulation (QAM)-modulated signals and space-time block coded signals using an optimal expectation-maximization (EM)-based iterative estimation algorithm in a multiple-input and multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) mobile communication system. An initial sequence estimation value is produced on the basis of a predetermined initial value using a pilot sub-carrier contained in each of OFDM signals received by a receiving side. A normalized value of a received signal on a channel-by-channel basis is produced by a predetermined equation using orthogonality between the OFDM signals received by the receiving side. At least one subsequent sequence estimation value is produced using the initial sequence estimation value and the normalized value of the received signal on the channel-by-channel basis.

Abstract: An apparatus and method for up-link data communication that obtains user information from wireless signals transmitted from b mobile stations (b>1) among a mobile stations (a>2), each mobile station having an antenna includes c antennas (where c≧a) for receiving the wireless signal, a multi-channel receiving unit for extracting received signals from the wireless signal received by the c antennas, a channel value estimating unit for estimating impulse responses of channels that are formed between the mobile stations and the antennas, from the received signals and outputs the estimated impulse responses as channel values, and a information estimating unit for canceling interference between the mobile stations, from the received signal and the channel values, and estimates the user information from the result of the cancellation.

Abstract: A mobile communication system having M transmission antennas for receiving P information bit streams and encoding the received information bit streams with a space-time trellis code (STTC) according to an optimal generator polynomial; modulating the encoded P information bit streams in a predetermined modulation scheme and outputting modulation symbol streams; and puncturing at least one modulation symbol in a predetermined position from each of the M modulation symbol streams, and transmitting the punctured modulation symbol streams through the M transmission antennas, thereby increasing a data rate while maintaining maximum diversity gain.

Abstract: A method of managing network operation information in a mobile communication system is disclosed. The method comprises: establishing a database comprising information management tables comprising the network operation information; defining a message format to transmit the network operation information among the nodes; collecting the network operation information for cell areas managed by the nodes, according to a set period; packeting the collected network operation information in the message format using a predetermined general-purpose protocol; transmitting the packeted message to neighboring nodes; and analyzing the transmitted message to update the network operation information in the information management tables of the nodes in the database.

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: Network architecture for a mobile communication system includes a plurality of Internet protocol (IP) routers that serve as gateways for transmitting data from one mobile terminal to another mobile terminal over a public Internet network. The architecture also includes a home agent (HA) and an authorization authentication accounting (AAA) server, both of which are located on the public Internet network. The HA performs initial registration of mobile terminals, IP routing, and management of mobility of the mobile terminals. The AAA server performs authorization, authentication and accounting for the mobile terminals to allow the mobile terminals access to the public Internet network and stores AAA information of each of the mobile terminals. A plurality of radio access points (RAPs), which are respectively connected to the public Internet network via the IP routers, connect the mobile terminals to the public Internet network.

Abstract: A receiver for receiving complex symbols in a radio communication system, in which a symbol arranger collects signals from at least three transmitter antennas through at least one receiver antenna over four time intervals; a channel estimator estimates at least three channel gains from the three transmitter antennas to the receiver antenna; first and second decoders each compute metrics for all possible pairs of symbols using the received signals and channel gains, and detect two symbols having a minimum metric; And a P/S (Parallel to Serial) converter arranges the detected symbols in the right order. Each decoder linearly operates the received signals and channel gains, pre-detects two symbols using threshold detection, and outputs the pre-detected symbols as final symbols if the product of the product of the pre-detected symbols and a constant determined by the channel gains is a minimum.

Abstract: An apparatus using transmitting antenna diversity to combat degradation due to fading in a wireless communication system. At least two symbols of four symbols to be transmitted through four transmitting antennas are rotated by predetermined phase values. An encoder configures four combinations for four input symbols so that a sequence of four symbols can be transmitted once by each transmitting antenna during each time interval. The combinations are transferred to the four transmitting antennas during four time intervals. Before the four input symbols are transmitted to the transmitting antennas, at least two symbols selected from the four input symbols are rotated by predetermined phase values. Therefore, the maximum diversity order can be obtained, a transmission delay time can be reduced, and the effect of fast fading can be reduced.

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 apparatus uses transmission antenna diversity to compensate for fading. An encoder according to a first embodiment forms 4 combinations each including 3 symbols so that 4 input symbols should be transmitted only once at each antenna and each time interval, and delivers the combinations to the 3 transmission antennas for 4 time intervals, and two or more symbols selected from the 4 input symbols are phase-rotated by predetermined phase values before being transmitted via the transmission antennas. An encoder according to a second embodiment forms 3 combinations each including 3 symbols so that 3 input symbols should be transmitted only once at each antenna and each time interval, and delivers the combinations to the 3 transmission antennas for 3 time intervals, and two or more symbols selected from the 3 input symbols are phase-rotated by predetermined phase values before being transmitted via the transmission antennas.

Abstract: According to one aspect of the present invention, there is provided a signal transmission apparatus for a mobile communication system. In the signal transmission apparatus, a frame segmentation section segments an input frame into Bk bit group, where k=1, . . . , K. A first group of encoders encodes Bk bit group and outputs encoded symbols. A second group of encoders encodes other Bk, bit group and output other encoded symbols. Each encoded symbol is encoded again to the transmit antennas using different functions. A transmission section includes a plurality of antennas in groups of a predetermined number of antennas, and the total number N of antennas is larger than the sum of the number of antenna groups. The transmission antennas transmit symbols encoded by one of the encoders.

Abstract: A frequency reuse method in an OFDM mobile communication system is provided. Frequency resources available to each BS are divided into at least four frequency groups and a different or the same frequency reuse distance is set for each of the frequency groups. The frequency groups are sequentially assigned to cell areas of each BS such that lower frequency groups are available to a near cell area and higher frequency resource groups are available to a remote cell area.

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: Provided are a method and apparatus for compensating for a frequency offset in an interleaved frequency division multiple access. The method compensates for a frequency offset between a transmission signal and a reception signal for a uth user (1≦u≦U, where U denotes the number of users) in an interleaved frequency division multiple access.

Abstract: An apparatus and method for transmitting and receiving signals using multi-antennas are disclosed. The signal transmitting apparatus for transmitting signals to a plurality of receiving apparatuses, using multi-antennas, includes: a V generator which generates a beamforming matrix V for a predetermined channel; a water filling unit which does not perform water filling for a training signal that is pre-known by the receiving apparatuses, and performs water filling for a user signal to be transmitted by using the V matrix and predetermined control values; a V operation unit, which multiplies a signal output from the water filling unit by the V matrix and transmits the multiplied result through the multi-antennas; and a control value detector, which extracts the control values from signals received from the receiving apparatuses through the multi-antennas, and outputs a maximum value among the extracted values to the water filling unit.

Abstract: An orthogonal frequency division multiplexing (OFDM) communication method and apparatus adapted to channel characteristics are provided. The OFDM communication method includes changing at least one of a length of a transmission symbol, a format of a frame, and a format of the transmission symbol depending on a type of the transmission symbol and a radius of a cell, in which communication is performed. The OFDM communication apparatus includes a symbol inspector, for inspecting a type of a transmission symbol and outputting the result of the inspection as a first control signal, and a symbol and format converter, for changing at least one of a length of a transmission symbol, a format of a frame, and a format of the transmission symbol in response to the first control signal and a radius of a cell, in which communication is performed.

Abstract: Apparatuses and methods for efficiently transmitting and receiving multicast data having a scalable data structure preferably provide for the transmission of a first data stream at a basic data rate using a first modulation scheme that can be received by all receivers in a communications system, while simultaneously providing for the transmission of at least a second data stream at a higher data rate using a second modulation scheme that can be received by groups of receivers having higher data rate capabilities, thereby maximizing data communications to all receivers in the communications system. The transmitting apparatus preferably includes a stream generator that divides multicast data into a plurality of multicast streams, an encoding processor, a header processor that generates a header for each of the encoded multicast streams, a stream modulator that modulates each of the encoded multicast streams, and a frame generator for generating a transmission frame.

Abstract: In a communication system, an apparatus for receiving a signal transmitted through a channel having time-varying characteristics and for restoring original user information included in the received signal, preferably includes: a first channel characteristic estimator for estimating a signal representing the delay characteristic of the channel; a first channel characteristic predictor for decimating the estimated signal applied thereto, for predicting the characteristic values of the channel, for interpolating the predicted channel characteristic values, and for outputting the interpolated result as a first predictive characteristic signal; and a first receiver for generating a decision value from the first predictive characteristic signal and the received signal, restoring the transmitted signal using the estimated decision value, and outputting a restored transmitted signal, which is fed back to the first channel characteristic estimator.