Abstract:
A receiver adopting an OFDM(Orthogonal Frequency Division Multiplexing) mode and an apparatus and a method for detecting packets are provided to improve detection performance in an MB-OFDM channel environment which is affected by multiple path fading and has a reception sampling error by determining an effective packet by using complex multiplication of a cross correlation of a received signal and a delayed value as much as one sample in the cross correlation values. A cross correlation unit(304) obtains the cross correlation of a preamble symbol and a received signal. A delay unit(306) delays the outputs of the cross correlation unit as much as one sample. A complex multiplication unit(308) obtains the complex multiplication of the outputs of the delay unit and the outputs of the cross correlation unit. A determining unit(316) detects an effective packet by using the complex multiplication value and determines the effective packet by comparing the complex multiplication value with a critical value. A power calculation unit(312) obtains the power value of the received signal delayed as much as at least one sample.
Abstract:
본 발명은 무선 통신 시스템에서의 데이터 송신 방법 및 장치에 관한 것으로, 송신 신호의 신호 세기를 일정하게 유지하기 위하여, 프레임 구간별로 대응되는 확산 코드를 이용하여 데이터를 변조시키는 기저 대역 모뎀 송신부와, 상기 변조된 신호를 아날로그 형태로 변환하는 디지털 아날로그 변환부와, 상기 아날로그 형태로 변환된 신호를 상기 프레임 구간별로 상이한 증폭율을 이용하여 증폭한 후, 반송파에 실어 무선으로 송출하는 무선 송신부를 포함하여 구성되며, 이에 의하여 본 발명의 송신 신호를 수신하는 무선 수신기가 자동 이득 제어 동작을 원활히 수행할 수 있도록 한다. 또한 실제 사용될 데이터가 저장되는 페이로드의 신호 세기도 증대시켜 신호대 잡음비(Eb/No)를 높여주고, 이에 따라 무선 수신기의 전체적인 수신 성능도 향상되도록 한다. DS-CDMA UWB 시스템, 데이터 송신, 송신 신호의 신호 세기, 3진 확산코드, 2진 확산코드, 증폭율
Abstract:
본 발명은 OFDM(Orthodgonal Frequency Division Multiplexing) 시스템의 UWB(Ultra-Wide Band) 송신 방법 및 그 장치에 관한 것으로, 송출 데이터의 이미지 신호가 용이하게 제거되도록 하기 위하여, 코딩 및 변조된 주파수 영역의 신호를 오버 샘플링된 시간 영역의 신호로 변환하는 IFFT부를 포함하거나, 코딩 및 변조된 주파수 영역의 신호를 시간 영역의 신호인 OFDM 심볼로 변환하고, 상기 OFDM 심볼의 프리픽스(prefix)와 서픽스(suffix)가 상기 OFDM 심볼의 전후단에 사선으로 더 포함되도록 하는 IFFT부; 적어도 하나 이상의 필터 탭을 포함하여, 상기 OFDM 심볼의 신호에 대한 오버 샘플링을 수행하는 보간부를 포함하여 구성되며, 이에 의하여 이미지 신호 제거에 대한 정확도를 높일 수 있는 효과를 가진다. OFDM, UWB, 이미지 신호
Abstract:
A method and an apparatus for creating a link quality indicator in an MB-OFDM(MultiBand-Orthogonal Frequency Division Multiplexing) UWB(Ultra-Wide Band) system are provided to determine whether a transmission power control mode and a data transmission ratio mode are to be changed intuitively by generating an LQI based on requested reception powers for respective data transmission ratios. A DGC(Dynamic Gain Controller)(105) is driven according to an AGC(Automatic Gain Control) algorithm and controls a power gain of a received signal. An AGC(107) outputs a signal for controlling the AGC according to the AGC algorithm, extracts an AGC control index by using the AGC algorithm, and determines a CCA state. When the CCA state is high, the AGC generates an LQI(Link Quality Indicator) information, which is delivered from a physical layer to a MAC(Media Access Control) layer by using the AGC index. A receiver of an MB-OFDM system includes an LNA(Low Noise Amplifier)(101), a mixer(102), an oscillator(103), an LPF(Low Pass Filter)(104), the DGC, an ADC(Analog Digital Converter)(106), a DAC(Digital to Analog Converter)(108), the AGC, and a demodulator(109).
Abstract:
PURPOSE: An LQI(Link Quality Indicator) calculation apparatus of an orthogonal frequency division multiplexing system is provided to calculate an LQI without using an additional hardware device. CONSTITUTION: A receiving device includes a synchronization processing unit(100), a channel estimating and compensating unit(110), and an LQI calculating unit(120). The synchronization processing unit synchronizes a signal received through a channel. The channel estimating and compensating unit converts a synchronized signal in a time domain into a signal in a frequency domain and performs compensation for a converted signal using a channel estimating result about the channel. The LQI calculating unit calculates an LQI using the phase of the signal which the compensation is performed for. [Reference numerals] (100) Synchronization processing unit; (114) Channel estimating unit; (118) Tracking unit; (120) LQI calculating unit; (130) LQI table; (140) Medium access control layer;
Abstract:
PURPOSE: An interfere avoiding device of an ultra wideband signal receiver is provided to change a frequency band of an interfere target signal by artificially adding a frequency offset of a range smaller than a possession bandwidth of the interfere target signal to an ultra wideband signal including the interfere target signal. CONSTITUTION: An FFT(Fast Fourier Transform) input buffer(400) receives an ultra wideband signal including an interfere target signal. A frequency offset unit(408) adds a preset frequency offset to the ultra wideband signal. An FFT converting unit(404) performs the FFT of the ultra wideband signal to which the offset is added. An interference avoiding unit(406) detects the interfere target signal from the FFT ultra wideband signal. If receiving power of the interfere target signal is greater than a preset reference level, the interference avoiding unit changes an ultra wideband communication channel to avoid interference. [Reference numerals] (400) FFT input buffer; (404) FFT converting unit; (406) Interference avoiding unit; (408) Frequency offset unit(NCO)
Abstract:
PURPOSE: A transmitting device, a receiving device, and a transceiving method of a wireless telecommunications system are provided to increase data transmission capacity by carrying out a modulation operation through a 64-quadrature pulse height modulating method. CONSTITUTION: A plurality of transmission units(130a,130b,130c) respectively copes with a plurality of sub-bands. A splitter(120) selects at least one of the same transmission units according to the data transfer rate. The splitter transfers an input signal to the selected transmission unit. Each transmission unit changes an output signal received from the splitter. A scrambler(110) outputs the input signal by scrambling the source data. Each of the transmission units comprises an encoder(131) which performs channel coding in regard to the output signal from the splitter, a modulator(133) which modulates the output signal from the encoder, a reverse Fourier transformer(135) which transforms the output signal from the encoder from a frequency area into a time area.