CN105141566B - A kind of PTS method reducing SCMA systems PAPR - Google Patents
A kind of PTS method reducing SCMA systems PAPR Download PDFInfo
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- CN105141566B CN105141566B CN201510511470.9A CN201510511470A CN105141566B CN 105141566 B CN105141566 B CN 105141566B CN 201510511470 A CN201510511470 A CN 201510511470A CN 105141566 B CN105141566 B CN 105141566B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2614—Peak power aspects
- H04L27/2615—Reduction thereof using coding
Abstract
The invention belongs to wireless communication technology fields, more particularly to a kind of sparse CDMA (Sparse Code Multiple Access, SCMA) orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing in system, OFDM) the suppressing method of signal peak-to-average power power ratio (Peak to average power ratio, PAPR).A kind of PTS method reducing SCMA systems PAPR, utilize the multicast characteristic of SCMA, phase place is carried out to time domain resource block in two dimensions of user and frequency point, and using the sparse characteristic of code book, more alternative sequence can be obtained by a small amount of low-dimensional IFFT operations.
Description
Technical field
The invention belongs to wireless communication technology field more particularly to a kind of sparse CDMA (Sparse Code
Multiple Access, SCMA) orthogonal frequency division multiplexing (Orthogonal Frequency Division in system
Multiplexing, OFDM) signal peak-to-average power power ratio (Peak-to-average power ratio, PAPR) suppressing method.
Background technology
As LTE system puts it into commercial operation, ever-increasing number of users, ubiquitous network insertion and higher are faced
Communication quality demand, people have started the research to 5G.
SCMA systems because its better than LTE system link transmission quality and power system capacity at double and as new research
Hot spot.However as other systems based on OFDM, there is high peak-to-average power ratio (PAPR) in the SCMA systems based on OFDM, make
It obtains signal and generates non-linear distortion, and practical mistake after power amplifier.
In SCMA systems, since subscriber signal number is more, the defect of high PAPR becomes apparent, therefore, according to SCMA systems
The signal transmission form of system, the PAPR for reducing system are necessary.Traditional partial transmission sequence (Partial Transmit
Sequence, PTS) technology still can be applied in SCMA systems reduce the PAPR of ofdm signal, but the calculating of this method is multiple
Miscellaneous degree is higher, affects the application of this method in practice.
Invention content
In order to solve the deficiencies in the prior art, the characteristics of present invention combination SCMA systems, a kind of reduction SCMA systems are provided
The PTS method of PAPR, this method utilizes the multicast characteristic of SCMA, to time domain resource block in two dimensions of user and frequency point
Phase place is carried out, and using the sparse characteristic of code book, more alternative sequence can be obtained by a small amount of low-dimensional IFFT operations.
A kind of PTS method reducing SCMA systems PAPR, the specific method is as follows：
S1, frequency-region signal is handled in transmitting terminal, specially：
S11, by signal bit stream that i-th layer of length is N/2 after code book E mapping, obtain the frequency domain sequence that length is N
Xi, wherein i=1,2,3 ..., J, J indicate the signal bit stream number of plies；
S12, by X described in S11iInterleaved partitioning scheme is at the frequency domain sub-block that W length is NWherein, W is indicated in each code word
Nonzero element number, w=1,2,3 ..., W；
S13, remove described in S12In neutral element after obtain length be the short sequence of N/4 frequency domains
S2, time-domain signal is handled in transmitting terminal, obtains time domain alternative sequence, specially：
S22, the factor graph according to SCMA, by the obtained short sequence of J*W time domainIt is combined, obtains K time domain
Short sequenceWherein, K indicates the frequency points in factor graph, k=1,2,3 ..., K；
Wk-1=[1, exp (j2 π (k-1)/N) ..., exp (j2 π (k-1) (N-1)/N)]；
S25, by time domain sub-blockSuperposition obtains time-domain alternative signalsI.e.What can be obtained as a result, is multiple and different
Time-domain alternative signals；
S3, the signal that PAPR minimums are selected in time-domain alternative signals after parallel-serial conversion, are added cyclic prefix, pass through
D/A converting units, HPA units and upconverting unit are emitted；
S4, the time-domain signal received is handled in receiving terminal to obtain frequency-region signal Y；
S5, in receiving terminal to frequency-region signal Y processing described in S42, it is specific as follows：
S51, by frequency-region signal Y Interleaved partitioning schemes described in S4 at K frequency domain sub-block Yk；
S52, stack up acquisition frequency-region signal is multiplied by each frequency domain sub-block after phase factor
S53, the new code book of rotation acquisition is carried out to code book E described in S1
S6, the frequency-region signal that will be obtained in S52It is input in MPA receivers with the code book E obtained in S53, it is last defeated
Go out every layer of corresponding transmission signal.
Further, frequency-region signal Y is obtained described in S4, specially：
S41, by the signal received after down coversion and A/D converting units, remove cyclic prefix, obtained after serioparallel exchange
Obtain time-domain signal y；
S42, time-domain signal y described in S41 is carried out to FFT operations acquisition frequency-region signal Y.
The beneficial effects of the invention are as follows：
The present invention can reduce the PAPR of ofdm signal, make full use of SCMA systems applied in the SCMA systems of 5G
Multicast feature and code book sparsity carry out phase place to time domain resource block in two dimensions of user and frequency point, pass through
Low-dimensional IFFT operations obtain more time-domain alternative signals, hence it is evident that reduce the PAPR of ofdm signal, and transmitting terminal complexity compared with
It is low.
Receiving terminal obtains new code book using code book rotation and is effectively recovered originally transmitted as the input of MPA receivers
Signal.
Description of the drawings
Fig. 1 is the system block diagram of the present invention.
Fig. 2 is the factor graph of SCMA.
Fig. 3 is the receiving terminal process chart of the present invention.
Fig. 4 is the specific process chart of the present invention.
Fig. 5 is PAPR performance curves.
Specific implementation mode
The specific implementation mode of the present invention is introduced below in conjunction with the accompanying drawings：
The present embodiment is tested using Matlab emulation platforms, and systematic parameter is as follows：Sub-carrier number is N=256, the number of plies
J=6, available frequency point number K=4, Overflow RateHT 150%, phase rotation coefficient P1,j,P2,k∈ [± 1], simulation times 105,
Code book used is as shown in table 1：
The code book collection of 1 4*6 of table
Transmitting terminal processing：
The complex signal sequence that the binary bit stream that each layer length is 128 is 256 at length by respective codebook mapping,
Segmentation is interleaved to these signal sequences and obtains the subsequence that 12 length are 256, is done after then these subsequences are zero-suppressed
64 points of IFFT obtains time domain short message number.
Time-domain signal phase place generates alternative sequence.
The time domain subsequences of each layer are multiplied by phase factor P1,jAfterwards, these postrotational sons are combined according to SCMA factor graphs
Sequence obtains the signal sub-block that 4 length are 64, is then P to these time domain sub-blocks again2,kPhase place, according to IFFT
Property obtains the sub-block that 4 length are 256, is finally added these sub-blocks and obtains time domain alternative sequence.
The PAPR for calculating each alternative sequence selects minimum.
Receiving terminal processing：
By the signal received after down coversion and A/D converting units, removes cyclic prefix, obtained using serioparallel exchange
Time-domain signal is obtained, the time-domain signal, which is then carried out FFT operations, obtains frequency-region signal Y.
By frequency-region signal Y Interleaved partitioning schemes at 4 frequency domain sub-block Yk.Phase factor P is multiplied by each frequency domain sub-block2,kAfter fold
Add up acquisition frequency-region signalP is carried out to original code book group1,jRotation obtain new code book group
By frequency-region signalWith new code book groupIt is input in MPA receivers, finally exports every layer of corresponding transmission signal.
Emulation testing is carried out using the method for the invention.Compare the method and tradition PTS (including it is adjacent, at random, hand over
Knit segmentation) PAPR performances.As shown in figure 5, the PAPR rejections of the present invention are close with tradition PTS (random division mode),
And better than the PAPR rejections of tradition PTS (intertexture or adjacent fashion), however, as shown in table 2, generating identical alternative sequence
In the case of, the present invention required complex multiplication and complex addition number are much smaller than traditional PTS method.
2 main transmitting terminal complexity of table compares
Claims (1)
1. a kind of PTS method reducing SCMA systems PAPR, which is characterized in that include the following steps：
S1, frequency-region signal is handled in transmitting terminal, specially：
S11, by signal bit stream that i-th layer of length is N/2 after code book E mapping, obtain the frequency domain sequence X that length is Ni,
In, i=1,2,3 ..., J, J indicate the signal bit stream number of plies；
S12, by X described in S11iInterleaved partitioning scheme is at the frequency domain sub-block that W length is NWherein, W tables
Show nonzero element number in each code word；
S13, remove described in S12In neutral element after obtain length be the short sequence of N/4 frequency domains
S14, to described in S13It carries out N/4 point IFFT operations and obtains the short sequence of time domainI.e.
S2, time-domain signal is handled in transmitting terminal, obtains time domain alternative sequence, specially：
S21, will be described in S14It is multiplied by phase rotation coefficient p1,iThe short sequence of time domain after phase place is obtained, i.e.,
Wherein, P1,i∈{1,-1}；
S22, the factor graph according to SCMA, by the obtained short sequence of J*W time domainIt is combined, obtains the short sequence of K time domain
RowWherein, K indicates the frequency points in factor graph, k=1,2,3 ..., K；
S23, by the short sequence of time domainIt is multiplied by phase rotation coefficient p2,kObtain time domain subsequencesI.e.Its
In, P2,k∈{1,-1}；
S24, according to IFFT Operation Natures, by the short sequence of time domainThe time domain sub-block that length is N is obtained after being convertedI.e.Wherein,
Wk-1=[1, exp (j2 π (k-1)/N) ..., exp (j2 π (k-1) (N-1)/N)]；
S25, by time domain sub-blockSuperposition obtains time-domain alternative signalsI.e.The multiple and different time domains that can be obtained as a result,
Alternative signal；
S3, the signal that PAPR minimums are selected in time-domain alternative signals after parallel-serial conversion, are added cyclic prefix, turn by D/A
Unit, HPA units and upconverting unit is changed to be emitted；
S4, the time-domain signal received is handled in receiving terminal to obtain frequency-region signal Y, specially：
S41, by the signal received after down coversion and A/D converting units, remove cyclic prefix, when being obtained after serioparallel exchange
Domain signal y；
S42, time-domain signal y described in S41 is carried out to FFT operations acquisition frequency-region signal Y；
S5, in receiving terminal to frequency-region signal Y processing described in S42, it is specific as follows：
S51, by frequency-region signal Y Interleaved partitioning schemes described in S4 at K frequency domain sub-block Yk；
S52, stack up acquisition frequency-region signal is multiplied by each frequency domain sub-block after phase rotation coefficient
S53, the new code book of rotation acquisition is carried out to code book E described in S11
S6, the frequency-region signal that will be obtained in S52With the code book obtained in S53It is input in MPA receivers, finally output is every
The corresponding transmission signal of layer.
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106130688B (en) * | 2016-06-13 | 2019-06-21 | 电子科技大学 | A kind of Sparse Code multiple access access detection method of low complex degree |
| US10425198B2 (en) * | 2016-07-07 | 2019-09-24 | Huawei Technologies Co., Ltd. | System and method for communicating using SCMA |
| US10075315B2 (en) * | 2017-01-25 | 2018-09-11 | Huawei Technologies Co., Ltd. | System and method for communications with reduced peak to average power ratio |
| CN107181567B (en) * | 2017-05-12 | 2020-04-14 | 电子科技大学 | Low-complexity MPA algorithm based on threshold |
| CN109639617A (en) * | 2019-01-21 | 2019-04-16 | 中国地质大学（武汉） | A kind of bandwidth conservation type peak-to-average force ratio in optical OFDM system based on APTS technology inhibits system |
| CN109831281B (en) * | 2019-03-21 | 2020-10-02 | 西安电子科技大学 | Multi-user detection method and device for low-complexity sparse code multiple access system |
| CN110381003B (en) * | 2019-07-25 | 2021-08-17 | 电子科技大学 | Multi-user signal detection method aiming at peak-to-average ratio suppression in SCMA-OFDM system |
| US11133969B2 (en) * | 2019-09-04 | 2021-09-28 | Huawei Technologies Co., Ltd. | Low peak to average power ratio single tone sparse transmission |
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| CN101958873A (en) * | 2010-10-11 | 2011-01-26 | 华中科技大学 | Information transmission method for reducing peak to average power ratio of orthogonal frequency division multiplexing signal |
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