Abstract:
PURPOSE: A preamble generation device, a method thereof, a preamble receiving device and a method thereof are provided to improve data transfer rate as the size of the address information by detecting transmitting and receiving address to preamble. CONSTITUTION: A shift register input unit(110) inputs at least one among the address of the source node transmitting a frame and address of the receiving node receiving a frame to a shift register. An address sequence generation unit(120) generates address sequence of subcarrier number size of the preamble of the frame in the shift register based on the output value shifted by each clock. A preamble transform unit(130) changes the produced address sequence through the IFFT into the time domain signal of preamble. The preamble transform unit transforms calculated the modular(modulo) -2 to the IFFT by adding the produced address sequence based on the received node address and the produced address sequence based on the transmission node address.
Abstract:
PURPOSE: A channel sensing scheme using a natural quiet period in a cognitive radio system is provided to reduce transmission period by reducing the frequency of QP allocation through the energy detection with an NQP. CONSTITUTION: An NQP information collecting unit(401) searches, from a network having a data transmission and reception period and an idle period, the period in which data transmission is stopped. A channel searching unit(402) searches the searched period, and a channel searching information processor(403) determines the length of idle period based on the searching result. In a reservation-based mesh network, the period in which data transmission is stopped corresponds to an IFS(Inter Frame Space).
Abstract:
PURPOSE: A cassegrain antenna for high grain is provided to form a broadband antenna by forming different depths groove scattering parts with the concave part of a main reflection unit. CONSTITUTION: A feeding unit(130) radiates electric wave. A sub-reflection unit(120) reflects the radiated electric wave. A main reflection unit(110) includes a plurality of concavo-convex parts. The main reflection unit reflects the reflected electric wave from the sub-reflection unit. The concave part of the concavo-convex parts of the main reflection unit is formed along the trace of a parabola, parabolic, oblate, spheroid and spherical shapes.
Abstract:
본 발명은 무선통신시스템에서 피드백 전송 및 적응 전송 방법에 관한 것으로서, 피드백 양을 줄이면서 다중 사용자의 밴드-AMC 모드 및 다이버시티 모드를 지원함으로써, 데이터 전송 효율을 증가시킬 수 있는 채널품질정보 피드백 전송 및 적응 전송 방법에 관한 것이다. 본 발명에 따른 피드백 전송 및 적응 전송 방법은, 사용자 단말이 수신 신호로부터 채널품질정보를 도출하여 채널품질정보를 피드백할 부밴드를 선택하는 단계와, 사용자 단말이 부밴드의 선택 여부에 따라서 채널품질정보를 기지국으로 피드백하는 단계와, 기지국이 피드백된 채널품질정보에 의하여 전송 모드를 결정하여 결정된 전송 모드에 따른 적응 전송 파형을 송신하는 단계와, 사용자 단말이 기지국이 송신한 적응 전송 파형을 수신하고 결정된 전송 모드에 따라서 수신된 파형을 복원하는 단계를 포함한다. 무선통신, 피드백
Abstract:
A voltage controlled oscillator is provided to obtain a signal with high power without an additional circuit by connecting a transmission line of 1/4 wavelength to a source terminal of an FET for amplifying a buffer and matching the power with the length of a stub for biasing a coupling signal. A voltage controlled oscillator includes an oscillator, an amplifier, and a pair of transmission lines. The amplifier is cross-combined for oscillating a differential signal and is comprised of a pair of FET(2) to amplify the output of the oscillator and an inductor(1). The pair of transmission lines(7) are short-circuited in the source terminal of the FET. The FET of the amplifier connects a drain terminal for amplifying an oscillation frequency. The signal connection line is serially connected to the drain terminal of the FET of the amplifier. The transmission line includes a capacitor with a fixed value.
Abstract:
A method for feedback transmission and adaptive transmission in a wireless communication system is provided to improve data transmission efficiency by supporting a band-AMC mode and a diversity mode in time division or frequency division at the same time. A user terminal extracts the channel quality information from a receiving signal and selects a sub band to perform the feedback of the channel quality information(S10). The user terminal feeds back the channel quality information to a base station according to the selection of the sub band(S20). The base station determines the existence of the sub band channel quality information and detects the channel quality information(S30). The base station transmits an adaptive transmission waveform according to the transmission mode by determining the transmission mode by the channel quality information which is fed back(S50). The user terminal receives the adaptive transmission waveform transmitted from the base station and recovers the received waveform according to the determined transmission mode(S60).
Abstract:
A method and an apparatus for detecting a signal with cyclo-stationary characteristics are provided to efficiently perform a spectrum sensing by reducing a complexity of calculation in detecting a signal with cyclo-stationary characteristics. An apparatus for detecting a signal calculates cyclo-stationary characteristics values on a cyclic frequency domain of input signals(S110), normalizes the calculated cyclo-stationary characteristics values(S120), multiplies the calculated cyclo-stationary characteristics values each other(S130), compares the result values of multiplication with a critical value(S140), determines that the signal exists in the input signals in case a result value is larger than the critical value(S150), and detects the signal from the input signals(S160).
Abstract:
A channel set management method and a system thereof for a dynamic channel allocation which periodically manages idle channels in a recognition wireless communications system which dynamically assigns the frequency of channel are provided to select optimum mobile channel by providing information for determining suitable frequency. A channel estimator(230) predicts a channel condition and a channel environment about an idle channel based on the channel information obtained through the spectrum sense and communications protocol. A reliability decision device(250) evaluates the reliability about the predictable result. A channel set administration(270) gives available rank to the idle channel based on the evaluated reliability.
Abstract:
안테나 급전회로 및 스위칭 빔 형성 장치가 개시된다. 이 안테나 급전회로는 입력되는 신호를 분할하는 신호 디바이더; 외부에서 수신되는 제어신호에 따라, 스위칭 동작을 수행하는 스위칭 소자; 상기 스위칭 소자의 스위칭 동작에 따라, 상기 분할된 신호의 위상 천이를 발생시키는 복수의 위상 천이기들; 및 상기 위상 천이기들과 연결되어 있으며, 상기 스위칭 소자의 스위칭 동작에 따라 2 종류의 위상차를 갖는 2개의 섹터 빔을 형성하는 안테나들을 포함하는 것을 특징으로 한다.
Abstract:
본 발명은 직교 주파수 분할 다중 접속(Orthogonal Frequency Division Multiplexing Access : OFDMA) 기반 인지 무선 시스템에서의 동적 자원 할당 방법 및 이를 위한 하향 링크 프레임 구조에 관한 것으로, 이 방법은 기지국이, 현재 사용되지 않는 유휴주파수대역의 주파수 선택성 정도에 따라, 적어도 하나의 빈-상기 빈은 주파수 상에서 연속된 제1 복수 개의 부반송파들로 이루어짐-으로 이루어진 부채널을 할당하는 AMC부채널 할당기법 및 주파수 상에서 분산형 제2 복수 개의 부반송파들로 이루어진 부채널을 할당하는 다이버시티부채널 할당기법 중 하나를 선택하는 선택단계; 및 상기 기지국이, 상기 선택된 부채널 할당기법에 따라 단말에게 적어도 하나의 부채널을 할당하는 할당단계를 포함한다. 본 발명에 따르면, 인지 무선 시스템에서 하향 링크의 효율을 높일 수 있다. OFDMA/FDD, 프레임 구조, 부채널