More Signal To Replace Inhibit Papr Of Ofdm System Fanaticism Detection Algorithm

Orthogonal Frequency Division Multiplexing (OFDM) is one of the key oftechnology to B3G/4G in the evolution process, But it is well known that Peak toAverage Power Ratio (PAPR) is the biggest defect in OFDM system, which makes ahigh requirement for the linear dynamic range of the power amplifier of transmitter. Thepopular methods to solve the PAPR at the moment including coding technology,amplitude limit method, probability method.Not only the probability method does not as coding technology to avoid peakpower, but also doesn’t make nonlinear operation as limiting amplitude method, whichaims to reduce the probability of peak power of signals. The technology of probabilitymethod used is linear procedure, therefore, it won’t produce distortion of signals.Although the computation complexity of probability method is larger, which reduce thePAPR of signals sufficiently. Therefore, in this dissertation only probability method willbe selected as the entry point of study.There are two representative technologies in probability method: Selected Mapping(SLM) and Partial Transimit Sequence (PTS). The conventional SLM and PTS need totransmit Side Information (SI) at the transmitter so as to recover the transmitted data atthe receiver, which will reduce the utility of spectrum resources. Because thetransmission of SI may produce high PAPR, which is not considered in SLM and PTSmethods, so it may cause PAPR upwards.To make up for the defects of conventional SLM and PTS methods, in thisdissertation blind receiver for multi-signal replacement to inhibit PAPR of OFDMsystems is proposed. The main research works and results are listed as follows:1. Add the reference symbol separately to the real part and imaginary part of thetransmitted signals based on SLM. At the receiver side, the time domain signals cantransmit to spectrum domain signals by Fast Fourier Transmit (FFT), then, devide thespectrum domain signals into real part and imaginary part. Afterwards, through theanalysis of the size of the energy of received signals at different frequency point tofigure out which random phase shift sequence was used at the transmitter. Compared with the conventional method, not only does the proposed method in this paper maintainthe similar PAPR reduction performance and Bit Error Ratio (BER) performance, butalso reduce the computational complexity efficiently and increases the efficiency ofspectral utility.2. Phase extended based on SLM to reduce the PAPR of OFDM without SI to betransmitted. Compared with the reference, PAPR decrease in a certain extent, and canget better BER performance.3. Insert the reference symbols onto the transmitted data based on PTS, thereceiver can figure out the rotation factor of each subblock without side information,and then recovering the transmitted signals without distortion owe to the shift reducedby reference signals to transmit siganls. Compared with the PAPR reduction of OFDMsignals without side information transmission of the reference, not only does theproposed method in this paper have the signals to be transimitted at the pilot point, butalso no SI to be transmitted. Therefore, increased the efficiency of spectral utility.4.Amplitude extented and phase rotation based on PTS, both of them have twomodulation methods at the receiver, which makes the decoder types increase.