Abstract: An apparatus and a method for acquiring initial synchronization in a wireless communication system based on Orthogonal Frequency Division Multiplexing (OFDM) are provided. The apparatus includes a frame synchronizer for acquiring frame synchronization using a preamble signal, a first offset determiner for determining a first time offset and a first frequency offset based on the frame synchronization, a preamble identifier estimator for estimating a preamble identifier in a receive signal interpolated with the first time offset and the first frequency offset, and a second offset determiner for generating a first preamble signal and a first pilot signal corresponding to the preamble identifier, for derandomizing a preamble signal and a pilot signal, and for determining a second time offset and a second frequency offset. Thus, the initial synchronization acquisition time in a low Signal-to-Noise Ratio (SNR) environment can be reduced.

Abstract: An apparatus for controlling a gain of transmit antennas in a communication system. The transmit antenna gain control apparatus includes a controller for determining a gain of multiple transmit antennas on a basis of a transmit antenna having a minimum currently unused residual power among currently unused residual powers of the multiple transmit antennas used in the communication system.

Abstract: An apparatus is operable to control power of a base station in a distributed Multiple Input Multiple Output (MIMO) wireless communication system. At least one beamforming matrix is used for processing transmission signals to terminals included in a terminal set for a multiple access is determined. Minimum power values required for satisfying a minimum transmission rate of the terminals are determined. Whether optimum power values exist is determined using the minimum power values, the beamforming matrix, and a limit transmission power of the base station. When the optimum power values exist, transmission power values for respective terminals are determined in a range meeting the limit transmission power of the base station.

Abstract: An apparatus and a method for determining an optimum integer perturbation vector of a low complexity in a multiple antenna system include a transmitter that transmits data using an optimum integer perturbation vector of a low complexity in a multiple antenna system includes a module pre-processor, a shift pre-processor, and a precoder. The modulo pre-processor adds an integer perturbation vector to a transmission signal vector. The shift pre-processor phase-shifts a pseudo inverse matrix of a channel matrix using a phase angle. The precoder precodes a transmission signal vector perturbed by the integer perturbation vector using the phase-shifted pseudo inverse matrix of the channel matrix.

Abstract: An apparatus and method for supporting Peer to Peer (P2P) communication in a broadband wireless communication system are provided. A P2P zone within a frame used for the P2P communication includes at least one channel, each channel includes a broadcasting zone and a contention zone, and a P2P-mode transmit Mobile Station (MS) transmits a reference signal through a broadcasting zone of a channel to which itself belongs. The method MS includes determining an interference sum for each channel within the P2P zone, comparing the determined interference sums with each other, selecting a channel having the least interference sum, and transmitting information regarding the selected channel to a Base Station (BS).

Abstract: A method and apparatus enhances sounding performance for a broadband wireless communication system of a multi-cell environment. A grouping part groups a plurality of sounding sequences to a plurality of sequence groups. A first determiner determines a correlation between the sequence groups. A second determiner determines a least interference relation between sectors in a cluster. An allocator allocates the sequence groups to the sectors based on the correlation between the sequence groups and the least interference relation between the sectors.

Abstract: Method and apparatus for performing communication between a Base Station (BS) and a Mobile Station (MS) in a Broadband Wireless Access (BWA) communication system. A method includes determining, by the BS, a Pseudo Random Bit Sequence Identifier (PRBS_ID) for renumbering subchannels in a predetermined Partial Usage of SubChannels (PUSC) zone among a plurality of PUSC zones in a downlink (DL) frame, and transmitting, by the BS, the PRBS_ID to the MS within a Space Time Coding Zone Information Element (STC_ZONE_IE) of a DL MAP message included in the DL frame.

Abstract: In a communication system, information regarding a first modulation scheme applied to a frequency domain in a serving base station is received from the serving base station. A signal of the frequency domain is received. A second modulation scheme is set by estimating a modulation scheme applied to the frequency domain in at least one neighbor base station from the received signal. Channel state information is generated by estimating the received signal. An operation for selecting whether to use interference cancellation is performed using the channel state information, the first modulation scheme information and the second modulation scheme.

Abstract: Disclosed is a method of preventing a replay attack during a handoff in a communication system using a Mobile IPv6 protocol. A mobile node creates a CoA (Care of Address) by handoff and sends the CoA to a correspondent node, thereby creating a binding entry. Upon receipt of a binding update message including a HoA and a CoA from the mobile node or an attacker, the correspondent node searches a binding cache for a binding entry having the same HoA (Home Address) and CoA as included in the binding update message. If it is determined that the binding entry has the same respective HoA and CoA as contained in the binding update message, the correspondent node checks a Used field of the binding entry. If it is determined that the Used field of the binding entry is equal to a predetermined value, the correspondent node sends a reauthentication command message to the mobile node.

Abstract: A terminal is capable of transmitting an orthogonal sequence in a broadband wireless communication system. Operations of a transmitting end include generating a sequence corresponding to sequence allocation information of the transmitting end among a plurality of candidate sequences; generating a signal string corresponding to the sequence; and transmitting the signal string over a channel defined for transmission of the signal string.

Abstract: A Log-Likelihood Ratio (LLR) generating apparatus and method in a communication system using a spatial multiplexing scheme. The reception method includes acquiring at least one estimated transmit vector by demodulating a receive vector using at least one Multiple Input Multiple Output (MIMO) detection process; selecting one of the at least one estimated transmit vector as an optimum estimated transmit vector; calculating LLRs with respect to the optimum estimated transmit vector; calculating a weight to be applied to each of elements constructing the optimum estimated transmit vector; and applying the weight to each of the calculated LLRs. Accordingly, the present invention can generate the LLRs with high reliability similar to the LLRs of a Maximum Likelihood receiver by applying the weight to the LLRs generated from the estimated transmit vector.

Abstract: Disclosed is an apparatus for determining transmit power of an uplink frame transmitted from a subscriber station to a base station and transmitting data in a mobile communication system in which a downlink frame, transmitted from the base station to the subscriber station, and the uplink frame are time division-duplexed (TDD). The apparatus includes a receive power measurement unit for measuring receive power of signals received from the base station; a transmit power controller for determining the transmit power of the uplink frame from the receive power measured by the receive power measurement unit and information related to receptions of an uplink frame, which is received from the base station; and a transmission radio frequency processor for performing radio processing so that the uplink frame is transmitted according to the transmit power determined by the transmit power controller.

Abstract: A method for providing a single-frequency network (SFN) service between a base station (BS) and a mobile station (MS) in a wireless communication system. The BS sets a first segment indicator in a medium access control (MAC) message field before transmission, if a resource allocation scheme corresponds to general data transmission. The BS sets a second segment indicator in the MAC message before transmission, if the resource allocation scheme corresponds to single frequency-based data transmission. The MS receives the MAC message from the BS, and performs renumbering according to the first segment indicator or the second segment indicator included in the received MAC message.

Abstract: A method for transmitting uplink control information in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme is provided. A mobile station (MS) selects a target anchor base station (BS) with which the MS desires to communicate through a fast feedback channel, and transmits a codeword allocated to the selected target anchor BS to a current anchor BS. Upon receiving the codeword, transmitting to the MS, by the anchor BS, fast feedback channel allocation information for the selected BS corresponding to the received codeword. The MS switches to a new anchor BS corresponding to the fast feedback channel allocation information.

Abstract: An Iterative Detection and Decoding (IDD) receiving apparatus and method in a multiple input multiple output (MIMO) communication system. The IDD receiving apparatus includes an MIMO detector which generates soft decision values of coded bits by MIMO-decoding a receive vector, feedback priori information, and a list of candidate coded symbol vectors; a decoder which Soft-Input/Soft-Output (SISO)-decodes the soft decision values generated at the MIMO detector and feeds back soft decision values of the coded bits to the MIMO detector; a hard decision part which generates a coded symbol vector by performing a hard decision on the soft decision values generated at the decoder; and a list updater which generates a list of candidate coded symbol vectors using the receive vector and provides the list to the MIMO detector at a first iteration, updates the list using the coded symbol vector fed from the hard decision part, and provides the updated list to the MIMO detector at subsequent iterations.

Abstract: In a communication system, a first Downlink (DL) signal to be commonly received by all Mobile Stations (MSs) at a Base Station (BS) is generated. A second DL signal that all the MSs do not need to commonly receive is generated. The first DL signal is applied to an interference cancellation scheme. The first DL signal is transmitted in a first time interval. The second DL signal is transmitted in a second time interval.

Abstract: A method of allocating sub-channel signal interleaving patterns to BSs forming a wireless communication system that divides a frequency band into a plurality of sub-carriers and including a plurality of sub-channels, which are a set of predetermined adjacent sub-carriers. The method includes: creating a basic orthogonal sequence having a length identical to a number of the sub-carriers forming the sub-channel; creating a plurality of sequences having a same length as the basic orthogonal sequence by cyclic-shifting the basic orthogonal sequence a predetermined number of times or performing a modulo operation based on a number of the sub-carriers forming the sub-channel, after adding a predetermined offset to the cyclic-shifted basic orthogonal sequence; selecting a predetermined number of sequences corresponding to a number of the BSs from among the plurality of sequences; and allocating the selected sequences as the sub-channel signal interleaving patterns for the BSs.

Abstract: Disclosed is a method for controlling downlink power transmitted from a base station to subscriber stations in a mobile communication system employing an Orthogonal Frequency Division Multiple Access (OFDMA) scheme, in which data is carried from the base station to the subscriber stations by subchannels to each of which a plurality of subcarriers are assigned. The method includes the steps of receiving from the subscriber stations channel condition information of each of the subchannels together with information related to a subcarrier having a channel condition below a threshold from among at least one subcarrier included in each of the subchannels; calculating transmission power for each of the subchannels based on the received information; and transmitting each of the subchannels with the calculated transmission power, excluding the subcarrier having a channel condition below the threshold.

Abstract: The present invention is provided a method for allocating uplink resources in a communication system. The method includes calculating a scheduling metric for each Mobile Station (MS), selecting an MS with a high priority according to the scheduling metric, determining a Modulation order Product coding Rate (MPR) and a number of subchannels for the selected MS, and allocating the determined MPR and the determined number of subchannels to the selected MS and updating the scheduling metric for the each MS.

Abstract: A method for allocating a subchannel in a transmitter of an Orthogonal Frequency Division Multiple Access (OFDMA) cellular communication system in which an entire frequency band includes a plurality of bands, each of the bands includes a plurality of bins, and each of the bins includes a plurality of subcarriers. The method includes dividing a predetermined time interval into an Adaptive Modulation and Coding (AMC) subchannel time interval and a diversity subchannel time interval; selecting any one of the plurality of bands in the AMC subchannel time interval; selecting a predetermined number of bins among the plurality of bins in the selected band; and allocating the selected bins to the AMC subchannel.