KR980700750A

KR980700750A - OFDM-RECEPTION FOR CORRECTION OF FREQUENCY, TIME WINDOW, SAMPLING CLOCK AND SLOW PHASE VARIATIONS

Info

Publication number: KR980700750A
Application number: KR1019970703823A
Authority: KR
Inventors: 스타팬 니스트롬; 에릭 스타레; 마르텐 리그넬; 고랜 로쓰; 브리안 론로쓰; 비다르 링세트
Original assignee: 퍼시 에케달 페터슨; 노르딕 디지탈 티브이 아크티에볼아크
Priority date: 1994-12-14
Filing date: 1995-11-27
Publication date: 1998-03-30
Also published as: SE9404356D0; JPH10510958A; SE9404356L; SE504787C2; WO1996019056A1; AU4275196A; CN1170486A

Abstract

본 발명은 OFDM-수신기에서 주파수, 시간 윈도우 오차, 샘플링 클럭 및 위상 오차의 교정을 위한 방법에 대한 것이다. 디지탈 형태로 여러 캐리어들을 포함하는 한 신호내에서 전송되는 정보는 다수의 기호들로 이루어진 연속적인 프레임들을 포함한다. 각 프레임에는 적어도 하나의 엎-첩과 하나의 다운-첩이 배열된다. 주파수의 교정이 엎과 다운-첩의 분석을 기초하여 실행된다. 가중된 임펄스 응답의 또다른 주요 초점이 결정된다. 주요 초점의 위치는 시간 윈도우와 샘프링 클럭의 교정을 위해 사용된다. 또한 수신된 캐리어 위치로부터의 벡터들이 매트릭스 내 이들의 이상 위치들과 관련하여 등록된다. 수신된 벡터와 이상적인 벡터 사이의 각도가 결정되며 캐리어의 주파수에서 전송 함수의 크기와 좌표 원점으로부터의 벡터의 거리와 관련하여 가중된다. 가중된 각도 거리에 대하여 평균치가 계산된다. 얻어진 평균치는 위상 오차의 교정을 위해 사용된다. 얻어진 위상 오차와 이전의 위상 오차를 알게됨으로써 다음 수신에서 들어오는 위상 오차의 평가를 위해 사용된다.The present invention relates to a method for correction of frequency, time window error, sampling clock and phase error in an OFDM-receiver. In digital form, information transmitted in a signal containing multiple carriers includes successive frames of multiple symbols. At least one up-chip and one down-chip are arranged in each frame. A calibration of the frequency is performed based on the up-and-down-chirp analysis. Another major focus of the weighted impulse response is determined. The position of the main focus is used for calibration of the time window and the sampling clock. Vectors from the received carrier position are also registered with respect to their abnormal positions in the matrix. The angle between the received vector and the ideal vector is determined and weighted with respect to the magnitude of the transfer function at the frequency of the carrier and the distance of the vector from the coordinate origin. An average is calculated for the weighted angular distance. The obtained average value is used for correction of the phase error. Knowing the phase error obtained and the previous phase error is used for evaluation of the incoming phase error in the next reception.

Description

OFDM-RECEPTION FOR CORRECTION OF FREQUENCY, TIME WINDOW, SAMPLING CLOCK AND SLOW PHASE VARIATIONS

본 내용은 요부공개 건이므로 전문내용을 수록하지 않았음Since this content is a publicly disclosed case, the full text is not included.

제1도는 한 세트의 이진 상관기에 의해 수신기가 첩 신호들을 어떻게 발견하는 가를 그같은 정밀도로 먼저 개략적으로 설명하고 본 발명에 따라 시간 윈도우, 캐리어 주파수 및 위상을 조절함을 도시하는 도면.BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 first schematically illustrates, with such precision, how a receiver finds chirp signals by means of a set of binary correlators, and then shows the adjustment of time window, carrier frequency and phase in accordance with the present invention;

제2도는 OFDM-신호가 IFFT(인버스 패스트 푸리에 변환)에 의해 어떻게 발생되는가를 도시하며 IFFT에서의 각 엔트리가 한 캐리어에 해당함을 도시한 도면.Fig. 2 shows how an OFDM-signal is generated by IFFT (Inverse Fast Fourier Transform), in which each entry in the IFFT corresponds to one carrier;

Claims

At the OFDM-receiver the received signal is divided into symbols, symbols are assigned at intervals and reference symbols with a predetermined content at fixed intervals are assigned, each carrier is assigned a serial number and the reference symbols are transmitted in pairs. In the OFDM-demodulation method for frequency correction of possible carrier frequency, phase error, time window and sampling clock, a received reference symbol is analyzed in a receiver, and the content of the received reference symbols in terms of time and frequency is determined in the receiver. Indicates how the carrier frequency is adjusted, the impulse response of the channel is calculated from the signals of the reference symbols, the time window and the frequency of the sampling clock are performed, and the complex vector position of the received demodulated carrier is compared to an ideal position wherein the deviation from the ideal position is used for correction of phase error upon reception.

2. A region according to claim 1, wherein the positions of the complex vectors of the received demodulated carriers are arranged in a matrix system for each imaginary real part thereof, each vector being assigned a region and marked to exist in the region; A method according to claim 1, characterized in that a vector occurring within is at a constant angular position from an ideal position, said angular position being used for the calculation of the phase error.

The method according to any one of the preceding claims, wherein the magnitude of the received signal is different for different carriers depending on whether the receiver receives more signals, and the phase error evaluation for each carrier determines the magnitude of the transfer function at the current frequency. weighted according to , wherein a signal having a larger magnitude has a higher weight than a signal having a smaller magnitude.

The method according to any one of the preceding claims, wherein the vector has different weights depending on the magnitude, ie the distance from the origin of the coordinates, and such weights compensate the magnitude according to the effect of noise on the angle error, the coordinate origin An OFDM-receiving method, characterized in that the angular distance furthest from the angular distance is assigned a higher weight than the angular distance closest to the coordinate origin, and correction of the phase error is performed according to the weighted angular error.

Method according to any one of the preceding claims, characterized in that the most recently obtained phase error is compared with the previously obtained phase error and the phase error expected in the next order of reception is calculated.

A channel according to any one of the preceding claims, wherein the position of the main focus of the channel is determined, the position representing the actual position of the time window, the position of the time window being at the frequency of the sampling clock adjusted with respect to the difference. and adjusted with respect to the difference between the actual position and the desired position by the

An OFDM receiver as claimed in any preceding claim, characterized in that the magnitude and phase of the carriers in the reference symbols are related to the respective carrier frequency.

An OFDM receiver according to any one of the preceding claims, characterized in that the content of the reference symbols consists of chirp signals.

An OFDM receiver according to any one of the preceding claims, characterized in that reference symbols are transmitted in pairs, in which reference symbols forming the pair are assigned one in up-chirp and the other in down-chirp.

The method according to any one of the preceding claims, wherein the size and phase of the carriers in the face-up are ejπK By /N, and the size and phase of carriers in the down-chirp are ejπK It is specified by /N, where N is the number of carriers, k is the serial number of each receiver, and J OFDM receiver characterized in that it represents =-1.

※ Note: It is disclosed according to the contents of the initial application.