A communications device includes at least one memory device for storing complex exponential functions as approximations of sine and cosine basis waveforms A logic circuit adds and subtracts the complex exponential functions to generate an Orthogonal Frequency Division Multiplexed (OFDM) communications signal as a plurality of N data subcarriers that carry communications data The logic circuit provides efficient and accurate implementation of the IFFT for use as an OFDM modulator using additions of stored complex exponentials and modulation of the integer-valued QAM data symbols using logic shifts and sign changes (2's complement)

System and method for communicating data using efficient fast fourier transform (FFT) for orthogonal frequency division multiplexing (OFDM) modulation

A base station and terminal use methods of obtaining synchronization and system information in a wireless communication system. An operation of a base station includes generating a synchronization signal to be transmitted through a Synchronization Channel (SCH), generating a broadcast signal to be transmitted through a Broadcast Channel (BCH), and transmitting repetitively the SCH and the BCH by performing beamforming on the channels with different transmission beams.

Apparatus and method for synchronizing and obtaining system information in wireless communication system

A Channel Quality Indicator table for wireless multiple input multiple output (MIMO) networks is disclosed. In one embodiment, a method of generating a table for channel quality indicator (CQI) for an open loop MIMO transmission includes calculating performance of a link between a transmitter and a user end unit for each MIMO transmission mode over a range of average signal-to-noise ratio, and selecting the MIMO transmission mode that maximizes performance for each subset of the range of average signal-to-noise ratio. The method further includes storing the selected MIMO transmission mode and the corresponding subset of the range of average signal-to-noise ratio in a CQI table, the CQI table being stored in an user end unit and a base transceiver station of the open loop MIMO network.

CQI Table for Wireless MIMO Networks

A communication device comprising a transmission unit and a reception unit. The transmission unit is configured to transmit, to a first communication device, first information indicating a first set of subcarriers comprising of a plurality of subcarriers, and to a second communication device, second information indicating a second set of subcarriers comprising of a plurality of subcarriers. The reception unit is configured to receive a first Discrete Fourier Transform-spread-OFDM (DFT-S-OFDM) signal from the first communication device using the first information and a second Discrete Fourier Transform-spread-OFDM (DFT-S-OFDM) signal from the second communication device using the second information. Also, in the communication device, a portion of the second set of subcarriers can overlap with at least a portion of the first set of subcarriers in a time frame of a plurality of time frames.

Radio communication system, radio communication method, radio communication device, reception device, and program

A communications device includes a signal input for receiving signals such as a binary phase shift keyed (BPSK) communications signal having a repeated preamble bit or symbol pattern. A modem processes the communications signal and includes a demodulator and processor that generates an initial frequency offset estimate and phase error estimate by processing such as with a Fast Fourier Transform (FFT), that detects the repeated preamble pattern for a block of samples within the communications signal, correlates two halves of the block of samples with a plurality of different shifted sequences and determines a maximum correlation value for the shifted sequence that provides the maximum correlation value to establish a symbol timing estimate based on the known timing alignment of this shifted sequence. Radio circuitry is operative with the modem for processing communications data obtained from the communications signal.

Communications device and related method that detects symbol timing

A subcarrier allocating apparatus allocating data to be transmitted to a plurality of orthogonal subcarriers in an orthogonal frequency division multiplexing (OFDM) system, the apparatus including: a logical index generator (142) generating a logical index for allocating a data subcarrier to a physical index, the logical index being included with only data subcarriers and the physical index indicating a location of a substantial subcarrier within a symbol; an intermediate index converter (144) converting the logical index into an intermeidate index by performing a given operation on the generated logical index and a pilot location constant; and a physical index converter (146) converting the intermediate index into a physical index based on the number of data subcarriers on the left and right sides of a null subcarrier for insertion of a guard interval formed by the null subcarrier.

Subcarrier allocation apparatus and method, subcarrier de-allocation apparatus and method in ofdm system

The present invention relates an apparatus and method of estimating a signal-to-noise ratio (SNR) of a received signal when the received signal has a timing offset. An apparatus for estimating a signal-to-noise ratio (SNR) according to an exemplary embodiment of the present invention includes a fast Fourier transform (FFT) unit that performs a fast Fourier transform on a received signal to convert the received signal into a frequency domain signal; a preamble selector that extracts a preamble from the frequency domain signal; a correlator that correlates the preamble to a preamble reference signal generated by a receiver to calculate a correlation value; an entire power estimator that calculates entire power; a noise power estimator that applies a differential demodulation method to the correlation value to remove a timing offset and calculate noise power; and an estimating unit that uses the entire power and the noise power to estimate the signal-to-noise ratio (SNR).

Apparatus and method of estimating signal-to-noise ratio

The present invention relates to an apparatus and method of compensating for a frequency offset in an orthogonal frequency division multiple access system that is capable of efficiently estimating and compensating for the frequency offset. A receiver of the orthogonal frequency division multiple access system can individually estimate a fractional frequency offset and an integer frequency offset by using a downlink preamble signal. Further, the receiver can compensate for the frequency offset by adding the integer frequency offset once after completely compensating for the fractional frequency offset. Therefore, it is possible to efficiently compensate for the frequency offset.

Apparatus and method of compensating for frequency offset in OFDMA system

A terminal demodulation apparatus previously stores a received frame signal in a memory before inputting the same into a fast Fourier transform (FFT) unit, performs a demodulation to necessary information read from the corresponding memory, and has a separate data subcarrier memory and pilot subcarrier memory, and uses the signal demodulation method mixed with a subcarrier allocation method so as to easily demodulate various subcarrier allocation methods.

Terminal demodulation apparatus and method

A receiving apparatus of a mobile terminal receiving a signal in a synchronous OFDM system under a multi-cell environment, including a demodulation start controller performing frame synchronization and cell search using a received signal and outputting information on a demodulation start point and a to-be-demodulated neighbor cell; a FFT unit converting a time-domain signal into a frequency-domain signal; a scramble code generator generating scramble codes for the to-be-demodulated neighbor cell from the demodulation start controller and the current cell; a correlator multiplying a signal from the FFT unit and scramble codes from the scramble code generator and outputting correlation signals; demodulators provided corresponding to a current cell and a maximum number of neighbor cells to be demodulated, and demodulating the correlation signals; and a decoder decoding signals from the demodulators and restoring original information transmitted from the corresponding cell.

Jun-Woo Kim

Papers

Subcarrier allocation apparatus and method, subcarrier de-allocation apparatus and method in ofdm system

Apparatus and method of estimating signal-to-noise ratio

Apparatus and method of compensating for frequency offset in OFDMA system

Terminal demodulation apparatus and method

Synchronous orthogonal frequency division multiplexing receiving apparatus in multi-cell environment and method thereof