Patent application number | Description | Published |
20080214115 | Apparatus and method for estimating channel in multi antenna wireless communication system - The present invention relates to an apparatus and method for estimating a channel in a wireless communication system. The apparatus according to the present invention includes an estimator for initially estimating a channel response value by using a predetermined signal among reception signals, a detector for detecting transmission signals by using the channel response value and an operator for updating the channel response value by using detected transmission signals, a detection accuracy and reception signals. | 09-04-2008 |
20080247478 | Orthogonal frequency division multiplexing communication system, multi-hop system, relay station, and spatially layered transmission mode - An apparatus and method for data transmission in an Orthogonal Frequency Division Multiplexing (OFDM) communication system are provided. An OFDM system includes a reference Relay Station (RS) and a cooperative relay station respectively for performing an Spatially Layered transmission Mode (SLM) process by modulating a phase and magnitude of a signal by using a predetermined modulation order suitable for the reference relay station to obtain a spatially-layered signal and for delivering the spatially-layered signal to a target Mobile Station (MS); a Base Station (BS) for selecting the reference relay station and the cooperative relay station among a plurality of relay stations; and an mobile station for detecting data through Maximum Likelihood (ML) detection in which a signal having the largest ML is detected by comparing the received spatially-layered signal with a signal which is converted through the SLM upon receiving the spatially-layered signal from the reference relay station and the cooperative relay station. | 10-09-2008 |
20080247489 | APPARATUS AND METHOD FOR SUPPORTING DISTORTIONLESS VECTOR PERTURBATION IN MULTIPLE ANTENNA SYSTEM - An apparatus and method for supporting distortionless vector perturbation in a Multi-Input Multi-Output (MIMO) system are provided. The apparatus includes a transmitter for supporting distortionless vector perturbation in a MIMO system. The transmitter includes a label inserter for generating a label and for inserting the label into a user information bit, a scrambler for scrambling the user information bit inserted with the label and for generating N independent candidate sequences, a modulator for modulating the N independent candidate sequences according to a modulation scheme and a vector perturbation unit for adding a limited offset vector so that the modulated symbols are mapped to a constellation point in a feasible region. The apparatus and method provide vector perturbation with improved performance and reduced computational complexity. | 10-09-2008 |
20080248803 | APPARATUS AND METHOD FOR ALLOCATING FREQUENCY RESOURCE IN A COMMUNICATION SYSTEM - A method and apparatus for allocating resources for a mobile station in a communication system is provided. The method includes determining if a mobile station within a cell is located in one of a first region corresponding to a cell center, a third region corresponding to a cell edge, and a second region corresponding to an area between the first and third regions, allocating frequency resources within an entire frequency band to the mobile station when the mobile station is located in the first region, wherein the entire frequency band comprises at least a first frequency band and a second frequency band, allocating frequency resources within the first frequency band to the mobile station when the mobile station is located in the third region, and allocating frequency resources within the second frequency band to the mobile station when the mobile station is located in the second region. | 10-09-2008 |
20080310556 | Apparatus and method for detecting signal in multiple-input multiple-output (MIMO) wireless communication system - Receiving apparatus and method in a Multiple-Input Multiple-Output (MIMO) wireless communication system are provided. The receiver having N-ary receive antennas includes a decomposer for decomposing a channel matrix to a matrix Q and a matrix R through a QR decomposition; a detector for determining a candidate group of an n-th phase by estimating a plurality of transmit signal vectors by substituting a plurality of transmittable symbols into symbol combinations of a candidate group of a (n−1)-th phase as an n-th symbol and detecting (n+1)-th through N-th symbols using characteristics of the matrix R; a calculator for calculating square Euclidean distance values between the transmit signal vectors and a receive signal vector; and a determiner for determining the candidate group of the n-th phase by selecting transmit signal vectors having the smallest square Euclidean distance value among the transmit signal vectors. | 12-18-2008 |
20090061899 | APPARATUS AND METHOD FOR LOCATION ESTIMATION IN A WIRELESS COMMUNICATION SYSTEM - An apparatus and method for location estimation in a wireless communication system are provided. The method includes identifying if a received at least one signal passed through at least one repeater, when the received at least one signal is identified as having passed though at least one repeater, measuring a Base Station (BS) basis delay time and calculating a repeater basis delay time using the measured BS basis delay time, and estimating a location of the MS using the repeater basis delay time. | 03-05-2009 |
20090075659 | Apparatus and method for allocating resources based on error vector magnitude (EVM) in a broadband wireless communication system - A resource allocation in a broadband wireless communication system is provided. An apparatus for a base station in a broadband wireless communication system includes a manager for managing resources by dividing the resources into a plurality of regions based on a maximum supportable error vector magnitude (EVM) in a frequency axis; and an allocator for allocating resources of a region other than a first region, the region having the smallest maximum supportable EVM, to a service to which a maximum modulation and coding scheme (MCS) level is not applied. | 03-19-2009 |
20090097585 | Apparatus and method for generating per stream channel quality information in multiple-input multiple-output (MIMO) wireless communication system - The generation of per stream Channel Quality Information (CQI) in a Multiple-Input Multiple-Output (MIMO) wireless communication system is provided. An apparatus includes a receiver for receiving signals from a transmitting end via a plurality of antennas; an estimator for estimating channels per antenna in relation with the transmitting end using the received signals and constituting a channel matrix; and a generator for deriving per stream effective noise when a lattice reduction scheme is adopted and generating per stream CQI using the per stream effective noise. Thus, feedback information for a Closed Loop (CL) MIMO system can be produced by generating the per stream CQI using the effective noise obtained through the lattice reduction. | 04-16-2009 |
20090116590 | APPARATUS AND METHOD FOR DETECTING SIGNAL IN MULTI-ANTENNA SYSTEM - A method and an apparatus for detecting a signal in a multi-antenna system using a spatial multiplexing are provided. The apparatus includes at least one antenna for receiving a signal, a channel estimator for estimating a channel using the received signal, a detector for calculating multiplication values commonly used to determine a Euclidean distance using the receive signal and channel information and for detecting a transmitted signal by calculating Euclidean distances of one or more candidate symbols using the receive signal and the determined multiplication values and a decoder for demodulating and decoding the detected signal. Hence, the computational complexity of the signal detection can be mitigated. | 05-07-2009 |
20090147890 | Apparatus and method for canceling interference in multi-antenna system - An apparatus and a method for canceling interference based on Maximum Likelihood (ML) at a receiver of a multi-antenna system are provided. The method includes estimating a channel using a signal received over one or more receiver antennas; generating one or more weights using the estimated channel to cancel interference; detecting a candidate symbol having the shortest Euclidean distance through Maximum Likelihood using a first weight; and soft-decoding the candidate symbol using a second weight. Therefore, by receiving the signal based on the ML under the interference, the system capacity can be increased and the reception performance can be enhanced. | 06-11-2009 |
20090154335 | RECEIVING APPARATUS AND METHOD FOR SINGLE CARRIER FREQUENCY DIVISION ACCESS SYSTEM - A receiver and a receiving method for a Single Carrier Frequency Division Multiple Access (SC-FDMA) system are provided. The receiver includes a matrix selector for selecting a constant channel matrix according to a Multiple-Input Multiple-Output (MIMO) reception scheme, a channel equalizer for equalizing a multi-path channel to a specific path channel in a frequency domain by using the constant channel matrix, and a MIMO detector for detecting a Euclidean distance of transmittable symbols from a time-domain Transmit (Tx) signal by using the channel equalized in the frequency domain and then for selecting a symbol having a minimum distance. | 06-18-2009 |
20090156214 | Preamble design method for reducing overhead during handover in hierarchical cellular system - Provided is a handover method of a wireless communication system using a hierarchical cellular scheme. In the method, signal quality of a serving node is measured, so that whether to start scanning for a handover is determined. When the scanning for the handover starts, signal qualities of a serving cell including the serving node and one or more neighbor cells are measured through a first preamble including a first identifier for distinguishing a cell. An intra-cell handover or an inter-cell handover is selected using the signal qualities of the serving cell and the neighbor cells. Therefore, a terminal can easily distinguish between the inter-cell handover and the intra-cell handover, and an overhead during a handover can be reduced because an intra-cell handover procedure is simplified. | 06-18-2009 |
20090160710 | Method and apparatus for estimating location to support location based service of terminal in mobile communication system - A method and an apparatus for estimating a location to support a location based service of a terminal in a mobile communication system are provided. The method includes receiving first reference signals from three base stations, calculating TDOAs, and solving a first equation using the TDOAs based on the first reference signals; when a solution of determining a location of a terminal based on the first equation is real or imaginary values, receiving second reference signals from the three base stations, calculating TDOAs, and solving a second equation using the TDOAs based on the second reference signals; and when a solution of determining the location of the terminal based on the second equation is real or imaginary values, determining the location of the terminal based on a relation between the first equation and the second equation. | 06-25-2009 |
20090252246 | Receiving apparatus and method for maximum likelihood in a single carrier system - A receiving apparatus and method of a Maximum Likelihood (ML) scheme in a Single-Carrier (SC) system are provided. The apparatus includes at least two antennas, at least two Orthogonal Frequency Division Multiplexing (OFDM) demodulators, at least two subcarrier mappers, at least two OFDM modulators, and a detector. The antennas receive signals. The OFDM demodulators convert the signals into frequency domain signals. The subcarrier mappers confirm signals mapped to frequency domain subcarriers. The OFDM modulators convert the signals into time domain signals. The detector constructs at least one set for candidate transmission symbols and detects receive signals through ML detection using the set. | 10-08-2009 |
20090262871 | Receiver and method for detecting signal in multiple antenna system - Provided are a receiver and a method for detecting a signal in a multiple antenna system. The receiver includes a filter coefficient calculator and a signal detector. After separating a first signal portion and a second signal portion, the filter coefficient calculator calculates an MMSE filter coefficient using a Matrix Inversion Lemma such that an inverse matrix of the first signal portion has a predetermined constant value regardless of a repetition signal detection process. The signal detector detects a relevant transmission signal from an interference-removed reception signal using the MMSE filter coefficient. | 10-22-2009 |
20090286494 | Iterative tree search-based precoding technique for multiuser mimo communication system - An iterative tree search-based preceding method for a multi-user Multi-Input Multi-Output (MIMO) communication system includes determining a reference value of a cumulative branch metric of a candidate symbol, eliminating candidates having values that exceed the determined reference value of the cumulative branch metric of the candidate symbol, and registering values, which do not exceed the determined reference value of the cumulative branch metric of the candidate symbol, as entries, and selecting the least value from the values registered as the entries. Thereby, the method has low complexity and similar performance compared to an existing Sphere Encoding (SE) technique. | 11-19-2009 |
20090290516 | Automatic gain control apparatus and method in a wireless communication system - An apparatus and method for adaptively adjusting a target Received Signal Strength Indicator (RSSI) for Automatic Gain Control (AGC) in a full-duplex relay apparatus with an interference cancellation function. A Signal to Interference Ratio (SIR) estimation block estimates an SIR based on an interference signal estimated from a received signal and an interference-cancelled signal determined by cancelling the estimated interference signal from the received signal. A target RSSI determination block determines a target RSSI according to the estimated SIR. An AGC block adjusts a gain for the received signal based on the determined target RSSI. | 11-26-2009 |
20100046655 | APPARATUS AND METHOD FOR TRANSMITTING AND RECEIVING IN A MULTI-ANTENNA SYSTEM - Apparatuses and methods for transmitting and receiving in a multi-antenna system are provided. A receiver for reducing a quantization error of channel information feedback in a multi-antenna system includes a restore vector generator for selecting a codeword c | 02-25-2010 |
20100202572 | LLR COMBINING METHOD AND APPARATUS FOR HARQ IN WIRELESS COMMUNICATION SYSTEM - A Log-Likelihood Ratio (LLR) combining method and apparatus for Hybrid Automatic Repeat Request (HARQ) in a wireless communication system for reducing a number of the LLR bits of previous packet stored for LLR combining are provided. The LLR combining apparatus includes an LLR combiner for combining a first LLR of a currently received packet and a second LLR of a previously received packet, an LLR buffer for storing the second LLR and a first packet exponent for recovering the second LLR in the same size as the first LLR, and an HARQ controller for determining whether the currently received packet is a retransmission packet or an initial transmission packet, and for controlling the LLR combiner to generate a third LLR by combining the first and second LLRs for the retransmission packet and to bypass the initial transmission packet. | 08-12-2010 |
20100271932 | APPARATUS AND METHOD FOR COMPENSATING FOR PHASE ERROR IN WIRELESS COMMUNICATION SYSTEM - An apparatus and method for compensating for a phase error in a wireless communication system are provided. The apparatus includes a reception modem, a transmission modem, a Common Phase Error (CPE) compensator, a first channel estimator, a phase compensator, and a second channel estimator. The reception modem demodulates and decodes a signal received. The transmission modem encodes and modulates a signal for transmission. The CPE compensator compensates for phase errors of at least two symbols constituting a signal. The first channel estimator estimates channels for respective bursts. The phase compensator compares phases for the channels for the respective bursts with each other and compensates for a phase difference between at least two bursts. The second channel estimator estimates an interference channel. | 10-28-2010 |
20110070881 | ANTI-INTERFERENCE APPARATUS AND METHOD IN WIRELESS COMMUNICATION SYSTEM - The present invention relates to an apparatus and method for reducing the interference caused by a femtocell in a wireless communication system. The method comprises the steps of: measuring the intensity of a signal received from a terminal when the transmission mode is deactivated; and controlling the transmission mode to be activated according to the signal intensity, and thus has the advantage of decreasing the influence effects caused by the femtocell and reducing the power consumption in a femto base station. | 03-24-2011 |
20110141935 | METHOD AND APPARATUS FOR RECEIVING MINIMUM MEAN-SQUARED-ERROR IN SINGLE-CARRIER FREQUENCY DIVISION MULTIPLE ACCESS SYSTEM - A method and an apparatus for receiving a Minimum Mean-Squared-Error (MMSE) in a Single-Carrier Frequency Division Multiple Access (SC-FDMA) system is provided. The method includes, transforming a signal in a time domain received through an antenna into a signal in a frequency domain, and discriminating between bands respectively allocated to terminals in a frequency domain, estimating a channel and computing a weight value from the signal transformed into the frequency domain, and detecting an MMSE, computing a time-domain bias from the weight value and a channel estimation value of the signal transformed into the frequency domain, normalizing the detected MMSE by using the computed time-domain bias, and transforming the normalized signal into a normalized signal in a time domain, decoding the normalized signal transformed to the time domain, and transmitting the decoded normalized signal transformed into the time domain to each of the terminals. | 06-16-2011 |
20120009867 | APPARATUS AND METHOD FOR LOCATION ESTIMATION IN A WIRELESS COMMUNICATION SYSTEM - An apparatus and method for location estimation in a wireless communication system are provided. The method includes identifying if a received at least one signal passed through at least one repeater, when the received at least one signal is identified as having passed though at least one repeater, measuring a Base Station (BS) basis delay time and calculating a repeater basis delay time using the measured BS basis delay time, and estimating a location of the MS using the repeater basis delay time. | 01-12-2012 |
20120020425 | APPARATUS AND METHOD FOR MINIMIZING ERRORS BY A CELL EDGE USER IN A MULTI-CELL COMMUNICATION SYSTEM - The present invention relates to performance improvement in a cell edge, particularly, to a method for selecting a precoder for a terminal in a multiple antenna system, wherein the method comprises: performing channel estimation for reference signals of a serving base station and another base station; determining a minimum singular value by using the channel estimation result; and if a complete collaborative feedback structure is used, feeding back a table of the determined, minimum singular value to the base stations. | 01-26-2012 |
20120203812 | METHOD AND APPARATUS FOR GENERATING SIGNAL HAVING CONVERTED SAMPLING RATE IN COMMUNICATION SYSTEM - A method of generating a signal having a converted sampling rate in a communication system is provided. The method includes selecting effective input samples among S number of input samples included in an input stream corresponding to an input sampling rate, generating a filter coefficient set including filter coefficients having a length of a second tap, the filter coefficients having the length of the second tap being generated by dividing a filter coefficient having a length of a first tap configuring a low-pass filter into the filter coefficients having the length of the second tap corresponding to a number of selected effective input samples, selecting filter coefficients corresponding to each of the effective input samples among the filter coefficients included in the filter coefficient set, and outputting output samples having an output sampling rate which is converted from the input sampling rate. | 08-09-2012 |