Method and apparatus for reducing PAR

Abstract

The invention provides a method for reducing the peak-to-average power ratio, which comprises distributing the code-modulated signals on a plurality of sub-carrier waves, and combining the sub carrier waves into a plurality of physical resource blocks; combining the physical resource blocks into a plurality of subsequences; searching the optimal phase after respectively subjecting each of the subsequences to the rapid Fourier reverse transformation; and carrying out the phase rotation according to the optimal phase corresponding to each of the subsequences. With the method and the device, the signals of the multicarrier are divided into the subsequences and then the phase rotation is carried out based on the PRB; and since the data and the pilot-frequency information is in the same PRB, a transmitting terminal can accurately demodulate without need of a transmission side band information receiving terminal while carrying out the phase rotation to the subsequences, and the BER deterioration is also prevented.

Description

technical field [0001] The invention relates to the technical field of mobile communication, in particular to a method and device for reducing peak-to-average ratio. Background technique [0002] OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) multi-carrier system uses orthogonal frequency division channels, so it can support high-speed wireless data transmission without complex equalization technology, and has strong anti-fading And the ability to resist inter-symbol interference, but the main disadvantage of the OFDM system is that it has a large peak-to-average power ratio (PAPR, peak-average powerratio), which directly affects the operating cost and efficiency of the entire system. Peak-to-average ratio problem is a common problem in multi-carrier modulation. [0003] In the prior art, in order to overcome the shortcoming that the OFDM signal peak-to-average ratio is too large, there are three main types of methods: the firs...

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Problems solved by technology

[0003] In the prior art, in order to overcome the shortcoming that the OFDM signal peak-to-average ratio is too large, there are three main types of methods: the first type of method is the clipping method, the second type of method is the sequence selection method, and the third type of method is the phase transformation method;

[0004] The principle of the first type of clipping method is simple. Generally, the probability of large peaks appearing is very small. The method of clipping is a more effective method to reduce the peak factor; but because clipping is a nonlinear processing, it will cause serious in-band Distortion and out-of-band noise, which will greatly reduce bit error performance and frequency band utilization; at the same time, although filtering after peak clipping can reduce adjacent channel interference, there will be peak regeneration, so multi-stage peak clipping filtering is often used in the prior art: For example, the TR (Tone ReseRvation) algorithm does not need to transmit sideband information. TR technology is essentially a limiting technology. Although out-of-band interference is avoided, and the complexity is relatively low without sacrificing spectrum efficiency, it will In-band noise is generated, and more importantly, the TR algorithm in the prior art still has a large amount of calculation, and the generated in-band noise is generally unable to be compensated, which will cause BER (Bit ErrorRate, bit error rate) to deteriorate

[0005] The second type of sequence selection method generally uses a complementary sequence to reduce the peak-to-average ratio. An orthogonal Golay complementary sequence Golay sequence combined with Walsh-Hadamard (WH) will be more effective in reducing PAPR, but this method needs to transfer edges. With information, and the amount of calculation is large, it is difficult to implement

[0006] The third type of phase transformation method is divided into selected mapping method (SLM, Selected Mapping) and partial transmission sequence method (PTS, Partial Transmit Sequences), both of which have the disadvantages of large amount of calculation and need to transmit side information

[0007] Therefore, in general, although the TR algorithm can effectively reduce PAPR, it has the disadvantage of introducing in-band noise

Although the SLM or PTS algorithm does not introduce in-band noise, it has the disadvantages of a large amount of calculation and the need to transmit sideband information. The transmission will lead to demodulation error of the entire slot, which is more serious than the BER degradation caused by the in-band noise brought by the TR algorithm. At the same time, the SLM or PTS algorithm needs to perform some complicated additional processing at the receiving end.

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