CN101005474B - New compression extension method for reducing OFDM signal peak to average ratio - Google Patents

New compression extension method for reducing OFDM signal peak to average ratio Download PDF

Info

Publication number
CN101005474B
CN101005474B CN2006100330168A CN200610033016A CN101005474B CN 101005474 B CN101005474 B CN 101005474B CN 2006100330168 A CN2006100330168 A CN 2006100330168A CN 200610033016 A CN200610033016 A CN 200610033016A CN 101005474 B CN101005474 B CN 101005474B
Authority
CN
China
Prior art keywords
companding
ofdm signal
peak
signal
function
Prior art date
Application number
CN2006100330168A
Other languages
Chinese (zh)
Other versions
CN101005474A (en
Inventor
曹若云
张琳
秦家银
Original Assignee
中山大学
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 中山大学 filed Critical 中山大学
Priority to CN2006100330168A priority Critical patent/CN101005474B/en
Publication of CN101005474A publication Critical patent/CN101005474A/en
Application granted granted Critical
Publication of CN101005474B publication Critical patent/CN101005474B/en

Links

Abstract

The method comprises: after sending end makes inverse fast Fourier transform (IFFT), it determines the amplitude value of OFDM signals. The invention provides a companding function for making transform in order to make the transformed amplitude value submits to the linear function distribution and the phase of signal keep unchanged; the receiving end makes inverse companding transform for amplitude value of the received signals, and then makes fast Fourier transform (FFT) and decode for it.

Description

A kind of companding method that reduces the ofdm signal peak-to-average force ratio
Technical field
The present invention relates to a kind of compand method that reduces signal peak-to-average ratio in the orthogonal FDM communication system, is a kind of by the ofdm signal amplitude is carried out the method that non-linear companding suppresses peak-to-average force ratio, belongs to communication technical field.
Background technology
OFDM (Orthogonal Frequency Division Multiplexing, OFDM) be the very high multi-carrier modulation technology of a kind of channel utilization, it can overcome the intersymbol interference that multipath fading causes effectively, thereby has obtained application in wireless communication systems such as WLAN.But, because ofdm signal is the superimposed results of a plurality of sub-channel signals, so in the transmitter of system, can there be bigger instantaneous peak value in composite signal, thereby produce excessive peak-to-average power than (Peak to Average Power Ratio, PAPR are called for short peak-to-average force ratio).These instantaneous peak values will produce nonlinear distortion during by the limited amplifier of the linear dynamic range in the transmission system, and the harmonic wave that is produced can enter relevant subchannel, causes interchannel interference, makes the performance rapid deterioration of system.Therefore, must take measures to reduce the peak-to-average force ratio of ofdm signal.
The method that reduces the ofdm signal peak-to-average force ratio at present mainly contains following several:
1. cut ripple
Promptly set an amplitude limit thresholding, the big amplitude signal that is higher than this thresholding is directly pruned.This is the simplest method, can be applicable to the system of the subcarrier formation of any number.But this method can cause signal distortion, causes the performance of BER decline of system and the increase of out-of-band radiation power.
2. encode
Utilize the different code characters that different coding produces and select the less code character of peak-to-average force ratio to carry out data information transmission.Shortcoming is as follows: the one, be subjected to the restriction of code modulation mode; The 2nd, be subject to number of sub carrier wave, along with the sub-carrier number purpose increases, computation complexity enlarges markedly; The 3rd, the data rate behind the coding decreases.
3. selectivity mapping
With the different random phase sequence of vectors of M respectively with the list entries dot product of IFFT, and then implement the IFFT computing, the output sequence of selecting wherein to have minimum peak-to-average force ratio transmits.Shortcoming is as follows: the one, and computation complexity is big, needs to calculate extra (M-1) group IFFT computing; The 2nd, need transmit relevant supplementary safely.
4. partial transmission sequence
The data symbol of input is divided into the experimental process group, and the length of each son group still equals the number of whole subcarriers, then each sub-component not multiply by certain weight coefficient, remerges this a little group at last, thereby reaches the purpose that reduces the whole system peak-to-average force ratio.The shortcoming of this method is similar to the selectivity mapping, and the one, computation complexity is big, and the 2nd, need transmit supplementary safely.
5. non-linear companding
At the transmitting terminal of communication system, reduce the amplitude of big amplitude signal and the amplitude of enhancing small magnitude signal by numerical transformation; And carry out inverse transformation to recover primary signal at receiving terminal.Up to the present concrete companding method has following three kinds:
The one, adopt the mu-law companding method of voice signal in handling to handle ofdm signal, it is exaggerated small amplitude signal, and signal is constant substantially significantly, thereby is that cost reaches the purpose that reduces peak-to-average force ratio with the average power that increase transmits.This method makes the performance number of signal more near the nonlinear change zone of power amplifier, causes the distortion of signal easily.
The 2nd, the Gaussian Profile of the real part and the imaginary part of original ofdm signal being followed by error function is transformed to even distribution respectively;
The 3rd, index companding method, the rayleigh distributed of the ofdm signal amplitude being obeyed by the companding function are transformed to even distribution (when d=1).
Method two and three all is to reduce peak-to-average force ratio by the statistical distribution characteristic that improves signal, discover that the distorted signals that these two kinds of methods cause is excessive, though the peak-to-average force ratio of the normalized ofdm signal of average power can be reduced to below the 4.78dB, system's bit error rate be increased to be difficult to practical degree.
Summary of the invention
Realize characteristics simple, that computation complexity does not increase with number of sub carrier wave in order to utilize non-linear companding method, and in order to overcome the shortcoming of existing companding method, guarantee before and after the companding that the average power of signal is constant, guarantee when effectively reducing peak-to-average force ratio, make system have lower bit error rate, the present invention proposes a kind of new companding method that is used to reduce the ofdm signal peak-to-average force ratio.
The invention has the beneficial effects as follows and realize by following proposal:
After the transmitting terminal of communication system carries out the IFFT computing, the Distribution Statistics of ofdm signal amplitude is transformed to the form of linear function by the companding function; Before the receiving terminal of communication system carried out the FFT computing, the inverse function by above-mentioned companding function carried out contrary companding transform with received signal amplitude, reduced the peak-to-average force ratio of ofdm signal thus.Above-mentioned companding function is:
y = 6 σ s ( 1 - exp ( - x 2 2 σ s 2 ) )
The inverse function of above-mentioned companding function is:
y = - 2 σ s 2 ln ( 1 - x 6 σ s )
Wherein, σ sThe average power of expression ofdm signal is opened the value behind the radical sign, that is σ s 2 = E ( | s n | 2 ) , s nRepresent original ofdm signal.
The value of ofdm signal amplitude behind companding is distributed as linear function, and its probability density function is:
f | t n | ( y ) = ky + b , ( k < 0 , b > 0 )
T wherein nSignal behind the expression transmitting terminal companding transform.
In technical scheme of the present invention, transmitting terminal/receiving terminal all is only the amplitude of signal to be done companding/contrary companding transform, the phase invariant of signal.
Adopt the amplitude of above-mentioned companding function to ofdm signal | s n| after carrying out companding transform, the average power of signal remains unchanged.
In the multi-carrier communications systems that the new compression extension method of the reduction ofdm signal peak-to-average force ratio that the present invention proposes is applied to adopt OFDM technology or other to have the peak-to-average force ratio problem.
Compared with prior art, advantage of the present invention is as follows:
1, the effect of new compression extension method reduction peak-to-average force ratio of the present invention is suitable with the selectivity mapping method, but its amount of calculation is far smaller than the selectivity mapping method;
2, new compression extension method of the present invention to cut wave effect so obvious unlike error function companding method and index companding method, therefore, under identical signal to noise ratio condition, system's bit error rate of new compression extension method is lower than the bit error rate of other two kinds of companding methods.
Generally speaking, it is compromise preferably that the new companding method of the invention has reached between peak-to-average force ratio and performance of BER, and do not need the computing of large amount of complex, therefore has higher utility.
Description of drawings
Fig. 1 is for adopting the ofdm system block diagram of amplitude companding transform method;
Fig. 2 is the companding function curve comparison diagram in index companding method and the companding method of the present invention;
Fig. 3 is the CCDF comparison diagram of peak-to-average force ratio behind several different companding methods of employing;
Fig. 4 is the CCDF curve that adopts peak-to-average force ratio behind the selectivity reflection method in the classical documents;
Fig. 5 is the bit error rate curve comparison diagram behind several different companding methods of employing.
Embodiment
Embodiment 1
As shown in Figure 1, the information source end of communication system produces 256000 bits at random, after the QPSK modulation, distributes to 256 subcarriers one by one, realizes quadrature modulation through IFFT then, obtains original ofdm signal.Average power to signal in the present embodiment has been done normalized.Obtain the amplitude of complex signal then, the new companding function that adopts the present invention to propose is done companding transform; The receiving terminal of communication system carries out before the FFT computing, and the inverse function by above-mentioned companding function carries out contrary companding transform with received signal amplitude.The companding function is
y = 6 &sigma; s ( 1 - exp ( - x 2 2 &sigma; s 2 ) )
The inverse function of companding function is:
y = - 2 &sigma; s 2 ln ( 1 - x 6 &sigma; s )
The peak-to-average force ratio of signal distributes behind the statistics companding, can obtain the simulation curve of its CCDF.After adopting the companding function of the present invention's proposition, when probability is 10 -4The time correspondence peak-to-average force ratio approximate 7.8dB, reached the purpose of effective reduction ofdm signal peak-to-average force ratio.
Embodiment 2
The basic procedure of another routine emulation experiment also as shown in Figure 1.The information source end produces 640000 bits at random, after the DQPSK modulation, distributes to 64 subcarriers one by one, realizes quadrature modulation through IFFT then, obtains original ofdm signal.Then obtain the amplitude of complex signal, the new companding function that adopts the present invention to propose is done companding transform, and the signal after will handling then is converted to serial from walking abreast, through sending into additive white Gaussian noise channel after steering D/A conversion and the up-conversion.
The signal that receiving terminal receives is parallel with signal from serial conversion after down-conversion, mould/transformation of variables, obtains the amplitude of complex signal then, and the contrary companding function that adopts the present invention to propose is done contrary companding transform, and then signal is carried out the FFT computing.Be serial with signal from parallel transformation subsequently, and, count the bit error rate of signal through the DQPSK demodulation.Through more as can be known, under identical signal to noise ratio condition, the bit error rate of the bit error rate ratio error function companding method of system and index companding method is much lower behind the employing new compression extension method.As seen the new compression extension method that proposes of the present invention is simple and practical, is a kind of scheme of more satisfactory reduction peak-to-average force ratio.
As shown in Figure 2, for the normalized ofdm signal of average power, the new companding function that the present invention proposes approaches the peak swing of large-signal , and index companding method is approached the peak swing of large-signal The thresholding of the former amplitude limit is the latter Doubly, so the signal distortion ratio index companding method that new compression extension method causes is little, hence one can see that adopts that the performance of BER of system is better than index companding method behind the new compression extension method.
As shown in Figure 3, adopt that the CCDF curve of the companding method that the present invention proposes is precipitous to end in the position that peak-to-average force ratio approximates 7.8dB.With CCDF curve (the Seung Hee Han that adopts peak-to-average force ratio behind the selectivity reflection method in the classical documents shown in Figure 4, Jae Hong Lee, An overviewof peak-to-average power ratio reduction techniques for multicarrier transmission, Wireless Communications, IEEE Volume 12, Issue 2, April 2005 pp.56-65) contrast as can be known, the effect that new companding scheme reduces peak-to-average force ratio is suitable with the selectivity mapping method, but its amount of calculation is far smaller than the selectivity mapping method.
As shown in Figure 5, under identical signal to noise ratio condition, the bit error rate of the bit error rate ratio error function companding method of system and index companding method is much lower behind the employing new compression extension method.What " ideal situation " was corresponding among the figure is the theoretical bit error rate curve of only considering DQPSK modulation system under the additive white Gaussian noise condition.

Claims (5)

1. a companding method that reduces the ofdm signal peak-to-average force ratio is characterized in that after the transmitting terminal of communication system carries out the IFFT computing, the statistical property of ofdm signal amplitude is transformed to the distribution of obedience linear function by the companding function; Before the receiving terminal of communication system carried out the FFT computing, the inverse function by above-mentioned companding function carried out contrary companding transform to received signal amplitude, reduced the peak-to-average force ratio of ofdm signal thus, and above-mentioned companding function is:
y = 6 &sigma; s ( 1 - exp ( - x 2 2 &sigma; s 2 ) )
The inverse function of above-mentioned companding function is:
y = - 2 &sigma; s 2 ln ( 1 - x 6 &sigma; s )
Wherein, σ sThe average power of expression ofdm signal is opened the value behind the radical sign, that is s nRepresent original ofdm signal.
2. the companding method of reduction ofdm signal peak-to-average force ratio according to claim 1 is characterized in that the ofdm signal amplitude is distributed as linear function in the value of transmitting terminal behind companding, and its probability density function is:
f | t n | ( y ) = ky + b ( k < 0 , b > 0 )
T wherein nSignal behind the expression transmitting terminal companding transform; | t n| the amplitude of the signal behind the expression transmitting terminal companding transform.
3. the companding method of reduction ofdm signal peak-to-average force ratio according to claim 1 is characterized in that transmitting terminal/receiving terminal all is only the amplitude of signal to be done companding/contrary companding transform, the phase invariant of signal.
4. the companding method of reduction ofdm signal peak-to-average force ratio according to claim 1 is characterized in that ofdm signal amplitude its average power behind companding remains unchanged.
5. the companding method of reduction ofdm signal peak-to-average force ratio according to claim 1 is in the multi-carrier communications systems that it is characterized in that being applied to adopt OFDM technology or other to have the peak-to-average force ratio problem.
CN2006100330168A 2006-01-17 2006-01-17 New compression extension method for reducing OFDM signal peak to average ratio CN101005474B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN2006100330168A CN101005474B (en) 2006-01-17 2006-01-17 New compression extension method for reducing OFDM signal peak to average ratio

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN2006100330168A CN101005474B (en) 2006-01-17 2006-01-17 New compression extension method for reducing OFDM signal peak to average ratio

Publications (2)

Publication Number Publication Date
CN101005474A CN101005474A (en) 2007-07-25
CN101005474B true CN101005474B (en) 2010-10-13

Family

ID=38704343

Family Applications (1)

Application Number Title Priority Date Filing Date
CN2006100330168A CN101005474B (en) 2006-01-17 2006-01-17 New compression extension method for reducing OFDM signal peak to average ratio

Country Status (1)

Country Link
CN (1) CN101005474B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102664853A (en) * 2012-04-23 2012-09-12 西安电子科技大学 Method for suppressing peak-to-average power ratio of wireless OFDM (Orthogonal Frequency Division Multiplexing) signal based on segmented distribution optimization
CN106385394A (en) * 2016-09-23 2017-02-08 西安电子科技大学 Method for suppressing peak-to-average ratio of orthogonal frequency division multiplexing (OFDM) signals

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101335734B (en) * 2008-01-08 2010-12-22 上海交通大学 Peak-to-average ratio reducing method and device based on approximate statistical sectional companding
CN101951355B (en) * 2010-09-16 2013-07-03 华南理工大学 Method for reducing peak-to-average ratio of lead code of OFDM
US20120148261A1 (en) * 2010-12-14 2012-06-14 Zte Corporation Method and system for optical orthogonal frequency division multiplexing with companding transform
US20120176886A1 (en) * 2011-01-10 2012-07-12 Zte Corporation Method and system for optical orthogonal frequency division multiplexing with hadamard transform combined with companding transform
CN102497345B (en) * 2011-12-12 2014-09-10 北京北方烽火科技有限公司 Method, device and system for reducing peak-to-average ratio of signals of orthogonal frequency division multiplexing
CN102404273B (en) * 2011-12-29 2015-04-15 电子科技大学 Method for transmitting OFDM signals based on new companding transform
US10230394B2 (en) 2014-09-19 2019-03-12 Telefonaktiebolaget Lm Ericsson (Publ) Methods for compressing and decompressing IQ data, and associated devices
CN104580059A (en) * 2015-02-13 2015-04-29 中国人民解放军理工大学 Method for suppressing peak-to-average power ratio in grid multi-carrier parallel transmission system
CN105871768B (en) * 2016-03-30 2019-02-22 东南大学 A kind of recoverable multistage linear companding method reducing peak-to-average force ratio in ACO-OFDM system
CN106209718A (en) * 2016-07-14 2016-12-07 上海交通大学 For the method and apparatus promoting DD ofdm system receiving sensitivity

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1392690A (en) * 2002-08-01 2003-01-22 上海交通大学 Amplitude compressino and expansion control method for peak-to-average ratio of orthogonal frequency division multi-plexing communication system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1392690A (en) * 2002-08-01 2003-01-22 上海交通大学 Amplitude compressino and expansion control method for peak-to-average ratio of orthogonal frequency division multi-plexing communication system

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
Xiao Huang等.Companding Transform for Reduction in Peak-to-AveragePower Ratio of OFDM Signals.IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS3 6.2004,3(6),2030-2038.
Xiao Huang等.Companding Transform for Reduction in Peak-to-AveragePower Ratio of OFDM Signals.IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS3 6.2004,3(6),2030-2038. *
江涛.新的低复杂度降低OFDM信号峰均功率比的压缩扩张技术.电子学报33 7.2005,33(7),1218-1221.
江涛.新的低复杂度降低OFDM信号峰均功率比的压缩扩张技术.电子学报33 7.2005,33(7),1218-1221. *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102664853A (en) * 2012-04-23 2012-09-12 西安电子科技大学 Method for suppressing peak-to-average power ratio of wireless OFDM (Orthogonal Frequency Division Multiplexing) signal based on segmented distribution optimization
CN102664853B (en) * 2012-04-23 2014-07-09 西安电子科技大学 Method for suppressing peak-to-average power ratio of wireless OFDM (Orthogonal Frequency Division Multiplexing) signal based on segmented distribution optimization
CN106385394A (en) * 2016-09-23 2017-02-08 西安电子科技大学 Method for suppressing peak-to-average ratio of orthogonal frequency division multiplexing (OFDM) signals
CN106385394B (en) * 2016-09-23 2019-03-26 西安电子科技大学 A method of inhibiting OFDM signal peak-to-average force ratio

Also Published As

Publication number Publication date
CN101005474A (en) 2007-07-25

Similar Documents

Publication Publication Date Title
JP5047834B2 (en) Wireless communication apparatus and wireless communication method
US7342978B2 (en) Method and apparatus for PAPR reduction of an OFDM signal
US8559552B2 (en) Dual carrier modulation precoding
KR100878720B1 (en) A modified SLM scheme with low complexity for PAPR reduction of OFDM systems
Baxley et al. Power savings analysis of peak-to-average power ratio in OFDM
US7746761B2 (en) Techniques to generate constant envelope multicarrier transmission for wireless networks
TWI405429B (en) Apparatus for transmitting data using carriers and method thereof
CN1956433B (en) Multi-carrier communication system
CN101958873B (en) Information transmission method for reducing peak to average power ratio of orthogonal frequency division multiplexing signal
CN101222468B (en) Peak-to-average ratio restraining method and device in multi-carrier orthogonal frequency division multiplexing system
CN101227446B (en) Method for reducing signal PAR based on self-adapting EVM
CN101867547B (en) Method for reducing peak-to-average power ratio of filter bank multi-carrier system
CN103297373B (en) Permanent envelope orthogonal frequency-division complex modulation method
Wang et al. PTS-clipping method to reduce the PAPR in ROF-OFDM system
US8223866B2 (en) Apparatus, and associated method, for communicating a data block in a multi carrier modulation communication scheme
CN104618082B (en) A kind of multiple antennas SIM OFDM multi-carrier wireless transmission methods
CN100484116C (en) OFDM communication system and method for reducing peak uniform power ratio
CN102638437B (en) Multi-carrier transmission method and device based on selected carrier modulation
CN105530217B (en) The signal of GFDM systems based on weighted score Fourier transformation emits and method of reseptance
CN101405962A (en) Apparatus and method for selecting modulation and filter roll-off to meet power and bandwidth requirements
CN102932289B (en) Cyclic shifting-based method for estimating shifting number and channel response in orthogonal frequency division multiplexing (OFDM) system
CN101783781B (en) Information transmission method for lowering peak to average power ratio of OFDM system signal
CN102957659B (en) Self-adaptive amplitude limiting method for reducing peak-to-average power ratio of OFDM (orthogonal frequency division multiplexing) system
CN100464543C (en) Compatible single-carrier OFDMA signal transmitting method
CN106357311A (en) Detection method of MIMO-OFDM (multiple-input multiple-output-orthogonal frequency division multiplexing) system based on SIM (subcarrier index modulation)

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
C14 Grant of patent or utility model
GR01 Patent grant
C17 Cessation of patent right
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20101013

Termination date: 20110117