OFDM diversity receiving device

Abstract

The invention acquires a synthetic signal with a higher quality than that of a single reception in an orthogonal frequency division multiplexing (OFDM) diversity reception. After signals received by individual antennas (111, 112) are subjected to fast fourier transform (FFT) treatments, C / N operation units (171, 172) calculate C / N ratios for individual symbol and smoothing units (181, 182) average the C / N ratios. A first weight calculation unit (19) inputs averaged C / N ratios (CN1, CN2) of the individual branch, and determines first weighting coefficients (Sigma1 and Sigma2) on the basis of those ratios (CN1 / CN2). The weighting coefficients (Sigma1 and Sigma2) and signals (X1, X2) multiple transmission line responses (H1, H2). Then the first weight calculation unit (19) calculates second weighting coefficients (W1, W2) based on the transmission line responses (Sigma1H1, Sigma2H2), and multiples second weighting coefficients (W1, W2) by weighted signals (Sigma1X1, Sigma2X2), thereby performing an MRC synthesization.

Description

technical field [0001] The present invention relates to an OFDM receiving device. Specifically, it relates to diversity reception technology for receiving OFDM transmission signals using a plurality of antennas. Background technique [0002] As a transmission method, the OFDM (Orthogonal Frequency Division Multiplexing) method has been adopted in Japanese terrestrial digital television broadcasting. The OFDM method is one of the multi-carrier transmission methods in which the transmission signal is divided into multiple carriers and transmitted. It has the advantages of dense allocation of the frequency spectrum of each sub-channel against the frequency selective fading of multi-path transmission, and high frequency utilization efficiency. [0003] In addition, so-called "hierarchical transmission" in which the frequency spectrum of a symbol signal having a bandwidth of 6 MHz to 8 MHz is divided into multiple layers and transmitted in the Japanese standard is availabl...

AI Technical Summary

Problems solved by technology

In this case, if the traditional MRC method is used for synthesis, the shunt with good C / N ratio will be affected by the shunt with poor C / N, and the C / N ratio after synthesis will become worse

[0017] In fact, if the 13-segment OFDM signal is received in diversity by the vehicle-mounted receiving device, and the experiment of synthesizing the received signal is carried out according to the MRC method, the following problem occurs: once the C / N ratio of the synthesized branch signal has a large difference, the diversity The combined BER (bit error rate) will be lower than the BER when single reception is performed in a branch with a good C / N ratio

Therefore, the zero-filled carrier signal cannot be received in single-segment mode

Therefore, the method proposed in the patent No. 2004-259634 cannot be utilized in the single segment mode

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