Abstract:
본 발명에 따른 무선랜 장치간에 공유하는 매체에 대한 접근제어를 위해 상기 매체접근제어구조를 포함하는 무선랜 시스템 장치에 있어서, 상기 무선랜 장치와의 인터페이스를 포함하는 시스템부; 상기 시스템부와의 인터페이스를 포함하고, 매체접근제어(MAC : Media Access Control) 프레임의 송수신 및 관리동작을 지원하는 상위 매체접근제어부; 상기 상위 매체접근제어부와의 인터페이스 및 상기 무선랜 장치의 데이터담당 송수신을 위한 장치와의 인터페이스를 담당하는 하위 매체접근제어부; 상기 하위 매체접근제어부와의 인터페이스를 통해 송수신되는 프레임의 변조 및 복조를 담당하는 모뎀부; 상기 모뎀부와의 인터페이스를 통해 송수신되는 신호의 무선신호처리를 위한 RF(Radio Frequency)부; 및 상기 RF부에서 처리하는 무선신호를 무선매체를 이용하여 송수신하기 위한 송수신단을 포함한다. 이 같은 본 발명에 의한, 무선랜 장치의 매체접근제어 구조는 IEEE802.11 규격의 시간 규약을 준수하며, DCF와 PCF 기능과 전원관리 기능 등을 지원할 수 있고, 무선랜 시스템의 QoS 요구를 수용하며, 이를 지원하기 위한 인터페이스를 지원하여, 추가적인 무선랜 매체접근제어에 대한 요구 기능을 수용할 수 있는 효과가 기대된다.
Abstract:
본 발명은 직교주파수 분할 다중 접속(Orthogonal Frequency Division Multiple Access, OFDMA) 기반 셀룰러 시스템의 자원 자원 공간 분할, 물리 채널 할당 및 전력 할당 방법에 관한 것으로, 다수의 인접한 셀에서 공통으로, 하나의 슬롯 내의 자원을 자원 공간으로 분할한 후, 분할된 자원 공간을 다수의 인접한 셀에서 각각 물리 채널의 크기에 맞추어 자원 집합으로 분할한다. 특성에 기초하여 분류된 물리 채널들은 하나의 자원 공간 내의 상기 분할된 자원 집합에 각각 할당된다. 본 발명에 따르면, OFDMA 기반의 셀룰러 시스템에서 특성이 다른 채널 별로 셀간 간섭을 용이하게 제어하고, 주파수 재사용 효율을 높일 수 있다. 또한, 서로 다른 두 셀 사이의 트래픽 채널이 전송되는 자원 공간을 부공간화하여 같은 부공간에 있는 트래픽 채널끼리만 충돌이 발생하도록 하고, 충돌이 일어나는 채널 사이에는 엄격한 전력 제어를 통하여 인접 셀로부터의 간섭을 제어하고 셀룰러 시스템의 주파수 재사용 효율을 높여 전체 시스템의 성능을 높일 수 있다.
Abstract:
본 발명은 이동통신시스템에서의 하향링크 신호 구성 방법 및 그 장치와, 이를 이용한 동기화 및 셀 탐색 방법과 그 장치에 관한 것이다. 이동통신시스템에서의 하향링크 한 프레임은 복수의 심볼로 구성되고, 각 복수의 각 심볼마다 시간축 및 주파수축을 기준으로 하여 파일럿 부반송파가 분산 배치되도록 삽입된다. 이 때, 먼저 하향링크 신호의 주기적 프리픽스와 하향링크의 유효 심볼의 자기상관이 최대가 되는 위치를 이용하여 초기 심볼 동기 및 초기 주파수 동기를 추정하고, 추정된 심볼 내에 포함된 파일럿 부반송파를 이용하여 셀 탐색 및 정수배 주파수 동기를 추정한다. 다음, 셀 탐색의 추정 결과를 이용하여 미세 심볼 동기를 추정하고, 미세 주파수 동기를 추정한 후, 하향링크의 프레임 동기를 추정한다. 그 후, 하향링크의 주파수 및 시간 추적을 수행하고, 하향링크 프레임에 삽입된 파일럿 부반송파 위치 집합을 이용하여 셀 추적을 수행하면서, 파일럿 부반송파를 이용하여 미세 심볼 동기 추적 및 미세 주파수 동기 추적을 반복 수행하여 하향링크 프레임의 주파수 및 시간 추적을 수행한다.
Abstract:
PURPOSE: A system and method for bridging packets between APs(Access Point) of wireless LAN and a recording medium storing program thereof are provided to support packet bridging function through a wireless medium between APs adjacent to a local basic service set. CONSTITUTION: A radio link channel(N2)is allocated for transmission between channels used for local BSSs(Basic Service Set)(15,25) and APs(10,20). and state information and an ID are assigned to specify that it is an equipment installed by an operator and performing a packet bridging. The first AP(10) is connected to a cable network(N1), wirelessly connected to terminals(11,12), and independently operates its BSS(15). The second AP(20) is connected to the first AP(10) by a wireless link in synchronization with the first AP(10) in time information and channel according to operation procedures of a PCF(Point Coordination Function) and a DCF(Distributed Coordination Function). The second AP(20) operates its BSS(25) independently from the cable network(N1).
Abstract:
PURPOSE: A WLAN(Wireless LAN) system device, a method for transceiving data through media access control and an operating method therefor are provided to wirelessly process a signal transceived by interfacing with a modem, and to transceive the processed wireless signal by using a wireless medium, thereby supporting DCF(Distributed Coordinated Function)/PCF(Point Coordinated Function) and a power management function as observing a time agreement of an IEEE802.11 standard. CONSTITUTION: A system portion(210) includes an interface with a WLAN device. An MAC portion(220) functions as an interface with the system portion(210), supports a power management function as observing a time agreement of a WLAN standard and transceiving a wireless frame, and performs a management operation in accordance with a QoS request. A modem portion(230) modulates and demodulates the frame. An RF portion(240) wirelessly processes a signal transceived through the modem portion(230). A transmission end(250) and a receiving end(260) transceive the wireless signal.
Abstract:
PURPOSE: A method for estimating the channel quality and applying the link of the orthogonal frequency divisional multiplexing wireless communication system and an apparatus for the same are provided to improve the data transmission throughput as well as to increase the usage time through the effective transmission power operation. CONSTITUTION: An apparatus for estimating the channel quality and applying the link of the orthogonal frequency divisional multiplexing(OFDM) wireless communication system includes an analog/digital converter(121), a protection period cancel block(122), a fast Fourier converter(123), a channel quality estimator(126) and a link adaptor(127). The analog/digital converter(121) converts the signal received from the outside into the digital signal. The protection period cancel block(122) removes the protection period from the converted digital signal. The fast Fourier converter(123) converts the protection period cancelled signal into the signal of the frequency region. The channel quality estimator(126) measures the quality of the channel considering the signal to noise and the delay diffusion by using the converted digital signal and the signal of the frequency region. And, the link adaptor(127) performs the link adaptation by selecting the parameter including the transmission power, the data modulation method and the transmission speed by using the protocol to identify the normal data transmission in the data transmission terminal and the reception terminal.
Abstract:
PURPOSE: A method for processing a protocol through frame prediction and comparison in a TDD(Time Division Duplex) wireless communication system is provided to improve turnaround speed in a transmission and reception mode transfer. CONSTITUTION: If communication is initiated, a CPU checks whether Tx data exist(801). If Tx data exist, the CPU makes a Tx frame and transmits it(802,803). Then the CPU stores a predictive frame to be received, based on the Tx frame(804). Afterwards, if a frame is received, the CPU compares the actually received frame with the predictive frame(805). If the actually received frame is identical to the predictive frame, the CPU skips a processing procedure for the actually received frame, first transmits an associated preamble(807), and then transmits the Tx data(808).
Abstract:
PURPOSE: A method of indirectly acknowledging a snoop protocol in accordance with states of wireless links and a packet transmission device of a wire/wireless integrated network performing the same are provided to use an indirect acknowledgement method for all data packets arriving at a base station during certain time, and to reduce an idle time of a transmission terminal as controlling the number of exceeding transmission times, thereby efficiently using bandwidth of a wire link. CONSTITUTION: When a transmitted ACK(Acknowledgement) packet arrives at a base station(42), the base station decides whether the packet is a new ACK packet(44). If so, the base station decides whether states of wireless links are abnormal(46). If so, the base station performs an ACK process(48). If the arriving ACK packet is not the new ACK packet, the base station decides whether the packet is overlapped(56). If so, the base station decides whether the arriving packet is an overlapping ACK packet(60). If not, the base station abandons the received ACK packet(62). The base station decides whether the number of data packets is the same as or smaller than a limit value of a base station buffer(64). If so, the base station creates an indirect ACK packet for the damaged packet to transmit the packet to a transmission terminal, and retransmits the damaged packet to a receiving terminal, then abandons overlapping ACK packets(68).
Abstract:
PURPOSE: A symbol timing estimation apparatus according to carrier frequency variation range and a method thereof are provided to estimate symbol timing using an output signal of a matching filter when a carrier frequency variation is small and to estimate it using an input signal of the matching filter when the carrier frequency variation is large. CONSTITUTION: According to the symbol timing estimation apparatus, a filtering unit(100) filters a sampling signal. An information generation unit(210) generates a control signal to determine whether to use an output signal of a signal selection unit(200) as the sampling signal or as a filtering signal from the filtering unit, according to the variation range of a received carrier frequency. The signal selection unit outputs one of the sampling signal and the filtering signal selectively, according to the control signal. And a symbol timing estimation unit(110) estimates the symbol timing of the signal selected by the signal selection unit.
Abstract:
PURPOSE: A device for detecting a burst signal and a method therefor are provided to calculate a high-speed input signal in real time to detect a burst signal, and to decide whether data frames exist as increasing accuracy of deciding a start point, thereby minimizing memory capacity. CONSTITUTION: An oscillator(105) samples input signals at fixed double sampling intervals. The sampled signals are matched by a matching filter(110). A queue(180) stores the matched signals in real time. A switch(170) controls transmission of the matched signals to the queue(180). A correlator(120) compares the matched signals with a preset preamble, and calculates correlation values to output the values. The first adder(123) adds an output of a Q-phase correlator(1212) to an output of an I-phase correlator(1220), and outputs an added value. A subtracter(124) subtracts an output of an I-phase correlator(1210) from an output of a Q-phase correlator(1222), and outputs a subtracted value. The first squarer(125) squares the output of the first adder(123). The second squarer(126) squares the output of the subtracter(124). The second adder(127) adds the output of the first squarer(125) to the output of the second squarer(126), and outputs the added value to a comparator(130). The comparator(130) compares the correlation values of the correlator(120) with a preset threshold value.