Abstract:
본 발명은 유무선 통합 IP 망을 경유하여 송신 서버와 수신 단말 사이의 패킷 유실과 송신 지연을 방지하는 TCP 프록시 설정 방법 및 그 시스템에 관한 것이다. 본 발명에 따른 핸드오버를 수행하는 방법은, 무선망 제어국이 이동 단말로부터 핸드오버 요구 메시지를 수신하는 단계; 상기 핸드오버 요구 메시지를 수신시에 상기 무선망 제어국이 TCP 프록시를 생성하여 종단 연결형 TCP를 분리 연결형 TCP로 전환하는 단계; 상기 TCP 프록시가 상기 단말을 대신하여 상기 핸드오버동안 상기 송신 서버로부터의 패킷의 수신에 대해 승인(ACK)하는 단계; 상기 TCP 프록시가 상기 서버로부터 수신한 패킷을 캐쉬에 저장하는 단계; 및 상기 무선망 제어국이 핸드오버 등록 메시지를 수신한 경우, 상기 저장된 패킷을 상기 단말로 전송하는 단계를 포함한다. 전술한 본 발명의 구성에 의하여, 핸드오버동안에만 TCP 프록시를 생성하여 패킷 유실 및 전송 지연없이 원활한 통신 환경을 제공할 수 있다.
Abstract:
본 발명은 낮은 복잡도를 갖는 디지털 정합 필터에 관한 것이다. 이 디지털 정합 필터는 복수의 곱셈기, 복수의 덧셈기 및 복수의 지연 소자를 포함한다. 복수의 곱셈기는 디지털 정합 필터의 중심점을 기준으로 좌우 대칭성을 가지는 필터 탭 중 중심점을 기준으로 일측에 위치하는 필터 탭과 수신 신호에 대한 곱셈 연산을 수행한다. 복수의 덧셈기는 복수의 곱셈기의 출력 신호와 이전 단까지 가산된 결과를 각각 더하여 다음 단으로 출력한다. 복수의 지연 소자는 복수의 덧셈기로 입력되는 이전 단까지의 가산된 결과를 특정 시간 지연시킨다. 본 발명에 따르면, SQRC 디지털 정합 필터의 탭 계수가 중심점을 기준으로 좌우 대칭성을 가짐을 이용하여, 하드웨어 구현시 요구되는 곱셈기의 개수를 줄임으로써, 하드웨어 복잡도가 감소되고 이로 인한 칩의 면적이 축소된다. 따라서, 무선 통신시스템에서 무선 채널을 통하여 수신된 신호의 신호대잡음비(Signal-to-Noise Ratio:SNR)를 최대화할 수 있다.
Abstract:
A symbol synchronization apparatus and method for synchronizing symbol digitally is disclosed. In the present invention, digital symbols are generated by an A/D converting unit. Based on digital symbols, a symbol timing value is calculated. The symbol timing value is used for determining a best symbol timing. According to the best symbol timing, a clock phase is determined and A/D converting unit uses newly determined clock for generating digital symbols. As a result, the present invention can perform an over-sampling process in higher resolution than a sampling frequency by using only one A/D converter. Therefore, the present invention may increase economic efficient and reduce complexity of hardware.
Abstract:
PURPOSE: A band request information transmission method and a mobile terminal using the same, a dynamic slot assignment method and a base station of a mobile communication system using the same are provided to insert 2-bit state information into data packets according to buffer changes of a mobile terminal, to transmit the information, and to transmit the number of exact requested slots by using another control packets, thereby enabling a scheduler of a base station to efficiently perform dynamic slot assignment. CONSTITUTION: An optional mobile terminal calculates the number of uplink data slots(110). Control packets are transmitted to a base station(120). The base station assigns uplink data slots of a next frame(130). Determined assignment information is transmitted to many mobile terminals through downlink control slots(140). The mobile terminal determines a band request information value(150). The mobile terminal transmits packets located in a buffer by using the assigned data slots(160). The base station predicts the number of data slots of the next frame requested by the mobile terminal(170). The base station assigns the next frame(180). The base station transmits determined assignment information to the mobile terminals through the downlink control slots(190).
Abstract:
PURPOSE: An apparatus and a method for synchronizing a digital symbol are provided to obtain the resolution of a narrower interval than an interval of sampling frequencies by using only one A/D converter. CONSTITUTION: An apparatus for synchronizing a digital symbol includes an A/D conversion portion(100), a symbol timing calculation portion(200), a timing decision portion(300), and an A/D clock supply portion(400). The A/D conversion portion performs an oversampling process for a received analog signal to a digital signal according to a clock. The symbol timing calculation portion calculates a symbol timing value from the oversampled signal in a sample interval. The timing decision portion decides the symbol timing from the symbol timing value. The A/D clock supply portion supplies an A/D clock to the A/D conversion portion according to the symbol timing information.
Abstract:
PURPOSE: A carrier wave recovering device for digital demodulation is provided to improve the signal recovery performance in the digital demodulation of signals distorted by the frequency offset, phase offset and the interference between symbols in multiple paths, by using a carrier wave recovering device incorporating an equalizer. CONSTITUTION: A carrier wave recovering device for digital demodulation includes a carrier wave recovering element(214) for compensating the phase and frequency errors with respect to an input signal according to a frequency control value, an equalizer(215) for receiving the signal from the carrier wave recovering element to compute an error due to the phase and the interference between symbols caused by the multiple paths, thereby correcting the signal distortion, and a sweeping element(216) for receiving the computed frequency error to transmit the frequency control value to the carrier wave recovering element according to the size of the error.
Abstract:
PURPOSE: A carrier wave recovering device for digital demodulation is provided to improve the signal recovery performance in the digital demodulation of signals distorted by the frequency offset, phase offset and the interference between symbols in multiple paths, by using a carrier wave recovering device incorporating an equalizer. CONSTITUTION: A carrier wave recovering device for digital demodulation includes a carrier wave recovering element(214) for compensating the phase and frequency errors with respect to an input signal according to a frequency control value, an equalizer(215) for receiving the signal from the carrier wave recovering element to compute an error due to the phase and the interference between symbols caused by the multiple paths, thereby correcting the signal distortion, and a sweeping element(216) for receiving the computed frequency error to transmit the frequency control value to the carrier wave recovering element according to the size of the error.