A Design Method of Ofdm-tdcs Waveform with Low Papr

Abstract

The invention belongs to the field of communication technology, and in particular relates to a low peak-to-average power ratio (Peak-to-Average Power Ratio, PAPR) OFDM-TDCS waveform design method in cognitive radio technology. A low PAPR OFDM-TDCS waveform design method, through reasonable design of the pilot pattern, avoids the situation that all pilots are unavailable due to pilot misalignment; by optimizing the pilot sequence, the PAPR value of the signal is reduced, and at the same time the PAPR controls the distortion brought by the pilot sequence; through the combination of noise shaping and limiting and out-of-band radiation control, the PAPR and out-of-band attenuation of the signal can meet the requirements of the cognitive radio system.

Description

technical field [0001] The invention belongs to the field of communication technology, and in particular relates to a low peak-to-average power ratio (Peak-to-Average Power Ratio, PAPR) OFDM-TDCS waveform design method in cognitive radio technology. Background technique [0002] Cognitive Radio (CR) technology was first proposed by Dr. Joseph Mitola III in 1999. Its core idea is to obtain the spectrum available at the current time through spectrum sensing, and use these spectrums for data transmission, so that the overall The utilization rate of spectrum is greatly improved. [0003] The Transform Domain Communication System (TDCS) uses the idea of ​​cognitive radio to dynamically change the spectrum waveform of the transmitted signal within a given spectrum range to avoid interference with authorized users. Document 1 "Addressing the control channel design problem: OFDM-based transformdomain communication system in cognitive radio (by Chuan Han, Jun Wang, Yaling Yang, and ...

AI Technical Summary

Problems solved by technology

First of all, in the OFDM system, the basic idea of ​​the pilot-based channel estimation method is that the transmitter inserts the pilot at an appropriate position, and the receiver recovers the pilot position and pilot sequence through the same pilot generation method; while in OFDM- In the TDCS system, due to the inconsistency of the electromagnetic environment between the transmitter and the receiver, the available spectrum of the transmitter and the receiver is inconsistent. At this time, the pilot position and pilot sequence generated by the transmitter are unknown to the receiver. , if the channel estimation is performed directly, the channel estimation may be completely wrong due to pilot misalignment. The existing OFDM-TDCS channel estimation methods reduce the influence of pilot misalignment by setting equivalent comb pilots. However The time-domain PAPR of the comb pilot is too high, resulting in pilot distortion after PAPR processing, which affects the performance of channel estimation

At the same time, like the OFDM system, the OFDM-TDCS system also faces the problem of high PAPR. Document 2 "Clipping noise cancellation in OFDM systems using oversampled signal reconstruction (by Hamid Saeedi, Masoud Sharif, and Farokh Marvasti.IEEE Communications Letters.2002,6( 2):73-75.)” proposes to use the Noise Sharping-Crest Factor Reduction (NS-CFR) method in the OFDM system to perform PAPR control on the time-domain signal, which can reduce the number of iterations, but applying it In cognitive radio technology, Adjacent Channel Rejection (ACI) may be caused due to insufficient out-of-band attenuation of the spectrum

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