Abstract:
Disclosed is a method for configuring an uplink frame in an OFDMA based wireless communication system. The total band of the uplink frame is divided into a predetermined number of subcarrier groups. Subcarriers within the respective allocated subcarrier groups are allocated to the subchannel defined for a predetermined number of consecutive symbols defined by slots in the uplink frame. Pilot subcarriers are allocated by the unit of the predetermined number of symbols so as to allow channel estimation from among the allocated subcarriers. Accordingly, data subcarriers are allocated by minimizing collision with specific users of adjacent cells so as to enable channel estimation using preambles in a cellular system, and some positions of the data subcarriers are allocated for pilots, thereby allowing synchronous demodulation and improving frequency reuse rates.
Abstract:
The present invention relates to a precoder and a precoding method in a multi-user multi-antenna communication system. When a transmission part having a plurality of antennas transmits a plurality of signals to a receiving part having an antenna, the precoder and the precoding method using the same prevents system performance degradation caused by interference signals and efficiently reduces transmission power while changing the constellation rotary angle. When the power is controlled by using the precoder, the system performance is enhanced while not damaging the structural gain of the existing multi-user multi-antenna precoder.
Abstract:
Ein Verfahren zum Senden von Daten durch ein Sendeendgerät zu einem Empfangsendgerät in einem drahtlosen Kommunikationssystem enthält: Erzeugen eines ersten Erfassungsfelds, das Symbole enthält, die unter Verwendung eines BPSK-Datentons moduliert werden; Erzeugen eines zweiten Erfassungsfelds, das Symbole enthält, die in der Weise moduliert werden, dass ein geradzahliger Hilfsträger und ein ungeradzahliger Hilfsträger eine Phasendifferenz von 90 Grad besitzen; Erzeugen eines Datenpakets, das das erste Erfassungsfeld, das zweite Erfassungsfeld und die Daten enthält; und Senden des Datenpakets.
Abstract:
The present invention relates to a beamforming method and apparatus. A beamforming method for use in a base station for transmitting a plurality of streams through a plurality of antennas includes: receiving feedback information including information on a first codeword selected from a codebook including a plurality of codewords from each of a plurality of user terminals; grouping the plurality of user terminals by use of the feedback information from each user terminal; determining a user terminal to which a plurality of streams will be assigned of the plurality of user terminals, and determining a second codeword to be used for beamforming from the codebook by use of the feedback information of each user terminal and grouping information; and multiplying data to be transmitted through the plurality of steams by the second codeword and a unitary matrix.
Abstract:
A receiver according to an exemplary embodiment of the present invention receives a transmitted signal, converts the signal to a predetermined symbol, and estimates channel information including a channel gain of a channel of the transmitted signal. In addition, the receiver generates an intermediate processing value for decoding the signal based on the estimated channel information and the symbol, and normalizes the intermediate processing value to the channel gain to generate a reference value. The generated reference value is used for a soft-decision value for decoding the signal. In addition, when the signal is decoded by using a hard-decision value, a constellation point value that is closest to the reference values is generated and set as the hard-decision value.
Abstract:
Disclosed is a method for constructing a downlink frame in a mobile data communication system using an OFDMA method. To construct the downlink frame, a single preamble is arranged at the head of the downlink frame, and a plurality of data symbols are arranged following the preamble. Then, a plurality of pilot symbols are inserted between the data symbols over the downlink frame at a predetermined period. Accordingly, a channel variation can be rapidly tracked using the preamble and pilot symbols. Furthermore, interference between adjacent cells is minimized and averaged to make a frequency reuse rate be 1, such that arrangement of multiple cells can be easily designed.
Abstract:
The present invention relates to a multi-input multi-output (MIMO) system for enhancin transmission performance. The MlMO system uses space-time encoding and transmi antenna selection methods, and includes a transmitter (100) and a receiver (200). Th transmitter (100) includes N transmit antennas (130-1 , 130-4) that are more than M tansrni antennas (130-1 , 130-3) used for tansmitting a signal to space channel, selects the M transmi antennas (130-1, 130-3) among the N tansmit antennas (130-3 130-4), and tansmits symbol by space-time encoding the symbol. The receiver (200) includes M receive antenna (120-1 , 210-2) for receiving a signal from the space channel, detects an information symb by using the signal received through the receive antenna (210-1 , 210-2), generates transmi antenna selection information for selecting M transmit antennas (130-1 , 130-3) among tansmit antennas (i30-1,...7130-4) with reference to a channel estimate, and returns th information to the tansmitter.
Abstract:
Disclosed is a MIMO-OFDM system, wherein the transmitter comprises a serial/parallel converter for converting continuouslyinputted symbols of the number of subcarriers to K parallel signals; a signal reproducer for reproducing K parallel signals by the number of transmit antennas L an eigenmode generator for generating eigenbeam of the reproduced signals outputted from the signal reproducer at each subcarrier, on the basis of Nf eigenbeam forming vectors which are fed backlong-term and information of a best eigenbeam forming vector at each subcarrier which is fed back short-term, through the feedback device; and aplurality of inverse Fourier converters for receiving the signals outputted from the eigenmode generator and generating an OFDM symbol.
Abstract:
Disclosed is a time-varying channel estimation method in an OFDM which comprises: (a) generating a pilot symbol by a comb type method for inserting a pilot symbol into a specific subcarrier for each interval in each OFDM symbol; (b) transmitting the pilot symbol to a receiver from a transmitter through a time-varying channel by using at least two multiple transmit antennas; (c) receiving the pilot signal through the time-varying channel; and (d) estimating a first channel of from among the time-varying channel according to an interpolation method which uses a temporal correlation of a second channel and a third channel.