Abstract:
A method and an apparatus for CQI(Channel Quality Indicator) control for adaptive modulation and coding in an OFDMA system improve capacity and fairness of the OFDMA system by variably controlling a size of a sub carrier group. A valid cluster is selected among clusters including one bin or more which are a plurality of subcarrier groups according to a predetermined standard(S335). An average CINR(Carrier-to-Interference-plus-Noise Ratio) of the valid cluster is calculated(S337). The optimum MCS level of each valid cluster is determined based on the average CINR value(S353). The optimum cluster among the valid clusters is determined based on the optimum MCS level(S373).
Abstract:
A method and an apparatus for CQI(Channel Quality Indicator) control for adaptive modulation and coding in an OFDMA system improve capacity and fairness of the OFDMA system by variably controlling a size of a sub carrier group. A valid cluster is selected among clusters including one bin or more which are a plurality of subcarrier groups according to a predetermined standard(S335). An average CINR(Carrier-to-Interference-plus-Noise Ratio) of the valid cluster is calculated(S337). The optimum MCS level of each valid cluster is determined based on the average CINR value(S353). The optimum cluster among the valid clusters is determined based on the optimum MCS level(S373).
Abstract:
An apparatus and a method for estimating a CINR(Channel Quality Indicator) of a system using a multi-carrier signal are provided to provide a more accurate CINR value to a base station by using a preamble boosted with a power value larger than a pilot and thus improve performance of a system using a multi-carrier signal. A preamble extracting units(31a,31b) extract a reception signal and sub-carrier signals having a noise component and an interference component among sets of every sub-carrier allocated to a preamble of a frequency zone. A preamble register(32) stores a preamble signal corresponding to the reception signal. A multiplying unit(33) multiplies the reception signal, the sub-carrier signal having the noise component and the preamble signal outputted from the preamble register(32) and outputs a generated signal. A CINR calculator(34) calculates a CINR value according to a sub-carrier allocation method by using the signal outputted from the multiplier(33), the sub-carrier signal having the interference component, and CQI(Channel Quality Indicator) period information. A controller(35) provides the CQI period information to the CINR calculator(34).
Abstract:
A synchronizing apparatus and a method for improving timing correction performance in an OFDM(Orthogonal Frequency Division Multiplexing)-FDMA(Orthogonal Frequency Division Multiple Access)/CDMA(Code Division Multiple Access)/TDMA(Time Division Multiple Access) system are provided to obtain a timing metric for generating a peak at an exact symbol timing location by using a preamble structure where patterns are repeated three times at a time domain after IFFT(Inverse Fast Fourier Transform) during symbol timing correction of a downlink preamble, thereby preventing performance deterioration of a traffic channel caused by synchronization errors. An auto-correlator(110) calculates an auto correlation value between a received signal and a signal that the received signal is delayed as much as Np. A power detector(120) calculates a power size of the received signal in order to normalize the auto-correlation value. A timing metric/normalization unit(130) divides the auto-correlation value by the power size of the received signal and normalizes the divided value to obtain timing metric. A peak detector(140) corrects a frame start location and an initial symbol timing by searching the maximum value of the timing metric by measuring a frame as moving from an arbitrary start point as much as a sample.
Abstract:
본 발명은 OFDMA/TDD 셀룰러 시스템에서의 상향링크의 동적 자원 할당 방법을 제공하기 위한 것으로, FLR 알고리즘을 이용하여 사용자별로 할당받을 수 있는 부채널의 개수를 정하는 단계; 라운드-로빈 알고리즘으로 첫 번째 프레임에 대한 채널 할당을 수행하는 단계; 상향링크 채널 사운딩을 통해 측정된 상향링크 채널정보를 이용하여 다음 프레임들에 대해 채널 할당을 수행하는 단계; 및 전력 제어를 수행하는 단계;를 포함하여 구성함으로서, 802.16e OFDMA/TDD 셀룰러 시스템 시스템에서 섹터 처리량과 공평성을 향상시키기 위한 하향링크 및 상향링크 동적 자원 할당 알고리즘을 제안할 수 있게 되는 것이다. OFDMA/TDD, 802.16e, 상/하향링크, 동적채널할당, 동적전력할당
Abstract:
본 발명은 OFDMA/TDD 셀룰러 시스템에서의 하향링크의 동적 자원 할당 방법을 제공하기 위한 것으로,GPF 알고리즘으로 부채널을 할당 받을 사용자를 선택하는 단계; 다른 사용자에게 할당되지 않은 부채널 중, 상기 선택된 사용자에게 가장 높은 데이터 전송률을 보장하면서, 상기 선택된 사용자를 제외한 다른 사용자에게 보장할 수 있는 데이터 전송률이 가장 낮은 부채널을 상기 선택된 사용자에게 할당하는 단계; 기지국 내의 각각의 사용자가 제공받을 수 있는 데이터 전송률 및 각 사용자가 요구하는 데이터 전송률의 크기를 고려하여 각 부채널에 전력 할당을 수행하는 단계;를 포함하여 구성함으로서, 802.16e OFDMA/TDD 셀룰러 시스템 시스템에서 섹터 처리량과 공평성을 향상시키기 위한 하향링크 및 상향링크 동적 자원 할당 알고리즘을 제안할 수 있게 되는 것이다. OFDMA/TDD, 802.16e, 상/하향링크, 동적채널할당, 동적전력할당
Abstract:
본 발명은 상호 대칭되며 반복되는 프리앰플 구조를 이용하여 시간영역에서 정수배 주파수 옵셋 추정 및 보다 정확한 심볼 타이밍 추정이 가능토록 하는 OFDM-FDMA/CDMA/TDMA 시스템에서 주파수 옵셋 추정 성능 향상을 위한 프리앰블 구조 및 동기화 방법을 제공한다. 본 발명에 따른 프리앰블은 시간영역에서 제1 샘플군 내지 제4 샘플군에 의해 4회 반복되며, 대칭형 구조를 가지되, 상기 제2 샘플군과 제4 샘플군은 상기 제1 및 제3 샘플군과 동일한 수의 샘플들이 제1 및 제3 샘플군의 샘플들의 수신된 순서와 역순으로 배열되어 정수배 주파수 옵셋 추정이 가능토록 된다. 이러한 본 발명은 시간 영역에서 패턴이 4번 반복되는 형태의 프리앰블 구조를 가짐에 따라 주파수 옵셋 추정 범위가 기존 IEEE802.16a/d/e 및 WiBro 시스템의 ±0.5에서 ±2.0으로 4배 향상되며, 프리앰블의 상호 대칭되는 특성을 이용한 임펄스 형태의 타이밍 메트릭을 생성함으로써 보다 정확한 심볼 타이밍 획득이 가능하다 OFDM-FDMA, CDMA, TDMA, 프리앰블 구조, 주파수 옵셋, 심볼 타이밍, 타이밍 메트릭
Abstract:
A preamble structure and a synchronizing method for improving frequency offset correction in an OFDM(Orthogonal Frequency Division Multiplexing)-FDMA(Orthogonal Frequency Division Multiple Access)/CDMA(Code Division Multiple Access)/TDMA(Time Division Multiple Access) system are provided to perform integer frequency offset correction at a time domain and more exact symbol timing correction by using the symmetric and repetitive preamble structure. A preamble is repeated four times by first to fourth sample groups in a time domain and has a symmetric structure. In the second and fourth sample groups, samples having the same number as the first and third sample groups are arranged in reverse order of an order that samples of the first and third sample groups are received. Integer frequency offset correction can be possible.
Abstract:
A device and a method for a frequency offset compensation in an OFDMA-TDD(Orthogonal Frequency Division Multiplexing Access-Time Division Duplexing) system are provided to reduce an acquisition time of a receiver by performing a frequency offset compensation three times in receiving one frame. A device for a frequency offset compensation in an OFDMA-TDD includes a frequency offset compensation unit(91), an A/D converting unit(92), a frequency offset detection unit(93), a loop filter unit(94), a PDM(Pulse Density Modulation) converting unit(95), and a voltage control oscillator(96). The frequency offset compensation unit(91) compensates a preamble signal received in an analog form and a frequency offset included in a DL-MAP symbol according to an offset compensation signal. The A/D converting unit(92) is connected to the frequency offset compensation unit(91) to convert the reception signal compensated in the frequency offset into a digital form. The frequency offset detection unit(93) measures a phase change of the reception signal transmitted through the A/D converting unit(92) to detect the frequency offset by using the measured value. The loop filter unit(94) removes a noise component from the detected offset value to output. The PDM converting unit(95) converts the output of the loop filter unit(94) into an analog value. The voltage control oscillator(96) generates an offset compensation signal according to the value converted from the PDM converting unit(95) and outputs the offset compensation signal to the frequency offset detection unit(93).
Abstract:
A method for allocating the dynamic resource of uplink in an OFDMA/TDD cellular system is provided to suggest a downlink and uplink dynamic resource allocation algorithm for improving sector throughput and fairness in the OFDMA/TDD cellular system. A method for allocating the dynamic resource of uplink in an OFDMA/TDD(Orthogonal Frequency Division Multiple Access/Time Division Duplex) cellular system comprises the following steps of: determining the number of sub channels which can be allocated according to a user using an FLR(Full Loading Range) algorithm(ST1); allocating channels to a first frame using a Round-Robin algorithm(ST2); allocating channels to next frames using uplink channel information measured through uplink channel sounding(ST3); and controlling power(ST4).