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86results about How to "Avoid multiplication" patented technology

Totally blind recognition method for coding parameter of convolutional code

InactiveCN103312457AAvoid randomness related phenomenaReduce the effects of noiseError preventionBit-lengthConvolutional code
The invention discloses a totally blind recognition method for a coding parameter of a convolutional code, which mainly solves the problems of incapability of realizing totally blind recognition and high calculation complexity existing in the prior art. The technical scheme provided by the invention is that: (1) the code length n, the input information bit length k and the register length m are solved according to the mutual check relationship between a convolutional code coder and an information code word; (2) when the code rate k/n is 1/n, two adjacent bits of the code word in the convolutional code bit stream are taken in sequence to construct an analysis matrix C, and fast Walsh-Hadamard transformation is used for the analysis matrix C to solve a generator matrix G; and (3) when the code rate k/n is (n-1)/n, the first to (n+1)th bits of the code word in the convolutional code bit stream are taken to construct an analysis matrix C, and fast Walsh-Hadamard transformation is used for the analysis matrix G to solve a basic check matrix H; and thus, the totally blind recognition for the coding parameter of the convolutional code is finished. According to the totally blind recognition method, the problem of totally blind recognition for the coding parameter of the convolutional code under the conditions of knowing no priori knowledge and containing an error code are solved well, and the operation complexity is simplified; and the totally blind recognition method can be used for multi-cast communication and intelligent communication.
Owner:XIDIAN UNIV

Large frequency deviation evaluation and correction method of orthogonal frequency multiplexing signal carrier

The invention relates to a large frequency deviation estimation and correction method for quadrature frequency division multichannel signal carriers, comprising the following steps: time domain frequency deviation estimation of frequency deviation, and time domain frequency deviation correction according to estimation results. The invention also comprises the following steps: smooth processing of the time domain frequency deviation estimation is performed, namely a low pass filter is adopted to smooth down peak values and valley values of time domain frequency deviation estimation values; after the time domain frequency deviation correction, Fourier transformation is performed; frequency domain frequency deviation estimation is performed on transformation results; frequency domain frequency deviation estimation results or time domain frequency deviation estimation results after smooth processing participate in time domain frequency deviation correction once again. The method of the invention overcomes limitation of the prior frequency domain algorithm on frequency deviation estimation and has the advantages of capability of processing large frequency deviation, capability of guaranteeing smooth signal processing, capability of quickly tracking frequency deviation caused by movement, and capacity of being conveniently realized in an integrated circuit design.
Owner:李文革

Iterative clipping and filtering method for reducing peak-to-average ratio of OFDM signals

The invention provides an iterative clipping and filtering method for reducing the peak-to-average ratio of an OFDM signals. The method comprises the steps of: firstly, calculating OFDM time domain signal power, and carrying out clipping on the real parts and imaginary parts of the OFDMs exceeding a power threshold P0 according to a clipping factor [alpha]; secondly, converting the OFDM time domain signals after the clipping into OFDM frequency domain signals by means of FFT conversion, and carrying out frequency domain filtering; then converting the signals after the frequency domain filtering into OFDM time domain signals by means of IFFT conversion, and finishing one time of iterative clipping and filtering processing; and finally, according to a maximum iterative number, repeating the above iterative clipping and filtering process. In the method, an OFDM system does not need to transmit additional information, additional processing on the OFDM signals on a receiving end for compensating the influences of the clipping processing on a sending end is not needed, the clipping factor [alpha] is suitably selected, the clipping processing is completed only by means of additive operation, and frequency domain filtering can be directly carried out on the processing result by means of the FFT conversion; in addition, in the iterative clipping and filtering process, a work clock multiplexing FFT/IFFT conversion unit higher than a sampling rate is adopted, and realization resources inhibited by the peak-to-average ratio are saved.
Owner:BEIJING RES INST OF TELEMETRY +1
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