摘要:
Provided are an apparatus and method for estimating and correcting a frequency offset in a multiband-Orthogonal Frequency Division Multiplexing Ultra-Wideband system using a time frequency hopping. The method includes the steps of: calculating a tangent input having a first value (X) and a second value (Y) by using PS symbols transferred over same frequency band with respect to one of a plurality of frequency bands used for frequency hopping; calculating tan(X/Y) using the first value (X) and the second value (Y), and calculating an index corresponding to the value of tan(X/Y) from a look-up table created by reflecting a relative frequency offset with respect to a center frequency; calculating indexes representing frequency offsets estimated with respect to remaining frequency bands used for frequency hopping from the look-up table by using the calculated index; extracting an index of a numerical controlled oscillator according to correction positions with respect to a plurality of frequency bands by using the calculated indexes; and correcting the frequency offsets estimated using the extracted indexes according to time frequency patterns by using a numerical controlled oscillator table.
摘要:
Disclosed is a method for controlling power level of received signal in an ultra wide band transmission system which uses multi frequency bands, and includes a pre-gain controller (PGC) and a voltage gain amplifier (VGA). The method for controlling a power level of a received signal includes the steps of: a) at the PGCs, detecting which multi frequency band is used in a transmitter of the transmission system; b) at the PGCs, obtaining the voltage gain owing to the discrepancy in the power levels of the received signals; and c) at the PGCs, compensating for the power loss based on the voltage gain.
摘要:
There is provided an apparatus for detecting a preamble packet in an orthogonal frequency-division multiplexing (OFDM) system, including: a cross-correlation calculating means for calculating a cross-correlation value between a received signal and previously stored preamble pattern values for an OFDM symbol region (N-point); a delay means for delaying the calculate cross-correlation value as much as a M-point interval; a receiving power measuring means for measuring a receiving power for the guard interval; and a dividing means for calculating a final cross-correlation value by dividing the delayed cross correlation value by the measured power.
摘要:
A rake receiver for DS-CDMA UWB system and a DS-CDMA receiver having the same are provided. The rake receiver includes: a channel estimator for estimating a channel having a predetermined chip duration by using a synchronization acquisition sequence; a tracking module for detecting a channel variation and adjusting a synchronization position value when the channel variation is detected; a first switch for selecting one of an output value of an analog-to-digital converter and an output value of a correlator and outputting the selected value; a second switch for selecting one of the output value of the analog-to-digital converter and the output value of the correlator; and a plurality of demodulators having a parallel processing structure to demodulate received signals by using the channel estimation value inputted from the channel estimator, the synchronization position value stored by the tracking module, and an output value of the second switch.
摘要:
There is provided an apparatus for detecting a preamble packet in an orthogonal frequency-division multiplexing (OFDM) system, including: a cross-correlation calculating means for calculating a cross-correlation value between a received signal and previously stored preamble pattern values for an OFDM symbol region (N-point); a delay means for delaying the calculate cross-correlation value as much as a M-point interval; a receiving power measuring means for measuring a receiving power for the guard interval; and a dividing means for calculating a final cross-correlation value by dividing the delayed cross correlation value by the measured power.
摘要:
An apparatus for detecting a signal in a common frequency band includes: a signal processor configured to extract a selected band signal from received wireless signals by filtering the received wireless signal based on a frequency selection control signal, convert the extracted signal to a baseband signal, and detect a predetermined signal; a sensing signal determiner configured to determine existence of the signal, output a determination result, and outputs a frequency selection generating signal when the predetermined signal is absent; and a frequency selection controller configured to output the frequency selection control signal by selecting a target band among a plurality of previously decided bands.
摘要:
Provided is a method and apparatus for acquiring OFDM synchronization even when it fails to detect a plurality of symbols at an initial stage. In the method, a frequency is adjusted to a first frequency band and a cross correlation value between a received preamble symbol and a preset preamble symbol is calculated. When the calculated cross correlation value is larger than a predetermined reference value and is first detected, frequency hopping is performed to receive subsequent symbols and cross correlation values to the subsequent symbols are reexamined. When the reexamined cross correlation value larger than the predetermined reference value is detected, timing synchronization, frequency offset estimation, and frame detection are performed.
摘要:
Provided is a method for adjusting Fast Fourier Transform (FFT) window positioning in a Multi Band Orthogonal Frequency Division Multiplexing Ultra-Wideband (MB-OFDM UWB) system. The method includes the steps of acquiring an initial FFT window position and a frequency hopping position, demodulating a received signal by using the initial FFT window position and the frequency hopping position acquired in the acquiring step, transmitting received data information to a Media Access Control (MAC) layer with a reception frame (RX frame) structure and judging at the MAC layer whether or not a packet error is occurred based on Frame Check Sequences (FCSs), and if no packet error is occurred, returning to the demodulating step, and if the packet error is occurred, changing a register map by using a predetermined interface line in a MAC-physical layer (MAC-PHY) interface to thereby adjust the FFT window position and the frequency hopping position, and then returning to the demodulating step.
摘要:
Provided is a method and apparatus for acquiring OFDM synchronization even when it fails to detect a plurality of symbols at an initial stage. In the method, a frequency is adjusted to a first frequency band and a cross correlation value between a received preamble symbol and a preset preamble symbol is calculated. When the calculated cross correlation value is larger than a predetermined reference value and is first detected, frequency hopping is performed to receive subsequent symbols and cross correlation values to the subsequent symbols are reexamined. When the reexamined cross correlation value larger than the predetermined reference value is detected, timing synchronization, frequency offset estimation, and frame detection are performed.
摘要:
Disclosed is a method for controlling power level of received signal in an ultra wide band transmission system which uses multi frequency bands, and includes a pre-gain controller (PGC) and a voltage gain amplifier (VGA). The method for controlling a power level of a received signal includes the steps of: a) at the PGCs, detecting which multi frequency band is used in a transmitter of the transmission system; b) at the PGCs, obtaining the voltage gain owing to the discrepancy in the power levels of the received signals; and c) at the PGCs, compensating for the power loss based on the voltage gain.