Abstract:
The present invention relates to a method for detecting signals using a condition number based on a MIMO-OFDM system and a device thereof. A method for detecting signals using a condition number based on a MIMO-OFDM system according to the present invention includes: a step of receiving signals with a MIMO-OFDM method from a transmission terminal which has a plurality of transmission antennae; a step of calculating a condition number for each received symbol; a step of comparing the condition number with the threshold value; and a step of detecting signals with a first algorithm as a detection method for received symbols of which condition number is smaller than the threshold value with reference to the compared result and detecting signals with a second algorithm as a detection method for the received symbols of which condition number is the same or greater than the threshold value. According to the present invention, in a MIMO-OFDM system, the complexity in a process of detection can be reduced compared to an existing detection method and the detection error can also be remarkably reduced by selecting a detection method as a V algorithm detection method using CLLL and a QRD-M detection method using DFE according to the channel condition number. [Reference numerals] (AA) Start; (BB) End; (S210) Receiving a signal in a MIMO-OFDM method from a transmission terminal; (S220) Calculating a condition number for the received symbol; (S230) Setting up the threshold value; (S240) Condition number of the received symbol
Abstract:
본 발명은 MIMO-OFDM 시스템에서의 그룹 시공간 순환 지연 수신 방법 및 장치에 관한 것이다. 본 발명에 따르면, 서로 다른 주파수 축의 서브 캐리어들에 대해 STBC(Space Time Block Code) 신호의 블럭과 SM(Spatial Multiplexing) 신호의 블럭이 서로 결합된 G-STCD(Group-Space Time Cyclic Diversity) 신호를 송신단으로부터 수신하는 단계와, 상기 수신된 G-STCD 신호로부터 상기 STBC 신호의 블럭과 상기 SM 신호의 블럭을 서로 분리하는 단계와, 상기 분리된 STBC 신호와 SM 신호를 각각 검출하는 단계, 및 상기 검출된 STBC 신호와 SM 신호를 서로 병합하는 단계를 포함하는 MIMO-OFDM 시스템에서의 그룹 시공간 순환 지연 수신 방법을 제공한다. 상기 MIMO-OFDM 시스템에서의 그룹 시공간 순환 지연 수신 방법 및 장치에 따르면, STBC 신호와 SM 신호가 결합되어 전송된 G-STCD 신호로부터 STBC 신호 및 SM 신호를 각각 분리 검출하고 병합함에 따라 다중화 이득과 다이버시티 이득을 효 과적으로 조절할 수 있는 이점이 있다.
Abstract:
PURPOSE: An OFDM system and a channel estimation method using the same are provided to efficiently estimate each MIMO channel by using an expanded CAZAC(Constant-Amplitude Zero-Autocorrelation) sequence. CONSTITUTION: A transmission device inserts nulls into a first CAZAC sequence. The transmission device generates the first CAZAC sequence. The transmission device transmits a signal including the first CAZAC sequence through a multiple antenna. A receiving device generates second CAZAC sequence having the nulls. The receiving device performs the autocorrelation-processes of the second CAZAC sequence with signals received from the transmission device. The receiving device estimates a multipath channel of the first CAZAC sequence.
Abstract:
PURPOSE: An apparatus and a method for frequency offset estimation in an OFDM system are provided to accurately estimate a frequency synchronization error of a received signal regardless of unbalanced quadrature phase by checking the property of an interferential signal. CONSTITUTION: A Fourier transform unit(110) performs the fast Fourier transformation of a received signal including successive first to third OFDM symbols. A first correlator(120) and a second correlator(125) respectively calculate a first correlation value and a second correlation value. A third correlator(130) and a fourth correlator(135) respectively calculate a third correlation value and a fourth correlation value. An adder(140) adds the first correlation value and the second correlation value. A subtracter(145) subtracts the third correlation value and the fourth correlation value. An imaginary number portion selector(150) selects an imaginary number portion value from added values. A real number portion selector(155) selects a real number portion value from subtracted values. An error operation portion(160) calculates a frequency error by using values which is generated by dividing a selected imaginary number portion by a real number portion.
Abstract:
PURPOSE: A method and device for demodulating an M-ary DCM based on an MB-OFDM system are provided to efficiently demodulate the M-ary DCM by considering a small number of candidate symbols. CONSTITUTION: A DCM demodulator receives a signal pair of an M-ary DCM by using estimated channel information(S310). A signal selector selects a signal with high reliability among the signal pair through a channel estimation method(S320). A prior detector detects a temporary candidate symbol from the selected signal(S330). A first candidate symbol selector selects C symbols as the candidate symbol(S340). A second candidate symbol selector selects the symbol corresponding to the bit stream of the selected C symbols(S350). A demodulator performs demodulation by using channel information and Euclidean distance between the C candidate symbols and each received signal value of the signal pair(S360).
Abstract:
PURPOSE: An optimal cooperating relay using cyclic delay diversity in multi-hop networks is provided to differently apply relaying method by the property of channels. CONSTITUTION: A determining unit(121) performs a CRC(Cyclic Redundancy Check). The determining unit decides the accuracy of the received signal. An estimating unit(122) sums the number of repeaters in which an error is generated at a hop based on the determined result of the determining unit. The estimating unit estimates a property of the previous channel. If the sum of error generated repeaters is larger than a predetermined threshold value, a transmit unit(123) transmits the received signal through a first relaying method.
Abstract:
본 발명은 OFDM 방송 시스템에서 채널추정 알고리즘의 복잡도 감소를 개시한다. 본 발명에 의하면, 수신된 신호는 파일럿간의 데이터를 이용하여 보간법으로 초기 채널추정하고, 기댓값 최대화 과정을 통해 전송된 신호의 가능성을 최대로 하는 기법을 통해 보다 정밀한 채널추정을 한다. 여기서, 역행렬 연산 과정을 뉴턴의 기법 도입으로 계산 과정을 간소화함으로서 복잡도를 줄일 수 있다.
Abstract:
PURPOSE: In the preamble symbol shift of data which the zero-crossing way of regulation of data sink is forged the Gaussian frequency shift keying, the zero-crossing counter is controlled. In that way zero-crossing is generated in the header symbol shift. CONSTITUTION: The data sink receives a message data forged the Gaussian frequency shift keying from data source(S510). The data sink stores the zero-crossed times in the storage(S520). The memory having the zero-crossing accumulated value which data sink most bigs of the input time point of final sample data included in preamble is detected(S530).
Abstract:
MIMO OFDM 시스템에서 사용될 수 있는 하이브리드 STBC 신호 복조 방법 및 장치가 개시된다. 본 발명에 의한, STBC (Space Time Block Code) 신호와 SM (Spatial Multiplexing) 신호가 혼합된 하이브리드 STBC 신호를 복조하는 방법에 있어서, 상기 하이브리드 STBC 신호를 수신하는 단계, 상기 수신한 하이브리드 STBC 신호에 포함된 STBC 신호를 검출하는 단계, 상기 수신한 하이브리드 STBC 신호로부터 상기 검출한 STBC 신호를 소거(cancellation)하여 SM 신호를 검출하는 단계, 상기 수신한 하이브리드 STBC 신호로부터 상기 검출한 SM 신호를 소거 (cancellation)하여 STBC 신호를 반복 검출하는 단계 및 상기 검출한 STBC 신호와 상기 반복 검출한 STBC 신호가 같으면 그 STBC 신호를 최종 STBC 신호로 결정하는 단계를 포함한다.