CN104202284A - Non-contiguous available sub-carrier CI-OFDM (Orthogonal Frequency Division Multiplexing) code adding method - Google Patents
Non-contiguous available sub-carrier CI-OFDM (Orthogonal Frequency Division Multiplexing) code adding method Download PDFInfo
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- CN104202284A CN104202284A CN201410422164.3A CN201410422164A CN104202284A CN 104202284 A CN104202284 A CN 104202284A CN 201410422164 A CN201410422164 A CN 201410422164A CN 104202284 A CN104202284 A CN 104202284A
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Abstract
The invention belongs to the technical field of communications, and particularly relates to a non-contiguous available sub-carrier CI-OFDM (Orthogonal Frequency Division Multiplexing) code adding method under the condition that the sub-carrier is non-contiguous and available. The non-contiguous available sub-carrier CI-OFDM code adding method specifically comprises the steps of obtaining spectrum information, performing CI code extension, zero-setting the position of an occupied sub-carrier, and obtaining a frequency domain sending signal Xfd after the CI code extension and performing OFDM transmission. In comparison with a traditional OFDM system emitter model, too much extra complexity and hardware expense are unnecessary as an N-point IDFT (Inverse Discrete Fourier Transform) operation is added. In comparison with the traditional OFDM, the non-contiguous available sub-carrier CI-OFDM code adding method greatly reduces the PAPR (Peak-to-Average Power Ratio) of signal transmission, enables the power distribution of the signal transmission to be more uniform, and reduces the design difficulty of the power amplification of the emitter. According to the invention, N-dimensional signals after added with Nzero 0 are subjected to the CI extension; the CI extension is performed directly on the N-Nzero modulation symbols in comparison with the prior art, so that the orthogonality of the sub-carrier is kept, and the PAPR of the signal transmission is further reduced.
Description
Technical field
The invention belongs to communication technical field, relate in particular at subcarrier discontinuous available in the situation that, a kind of discontinuous available subcarrier CI-OFDM code adding method.
Background technology
Cognitive radio technology is to be proposed in 1999 by Joseph Mitola doctor III the earliest, its core concept is to obtain by frequency spectrum perception the frequency spectrum that can use in current time, utilize these frequency spectrums to carry out the transmission of data, thereby greatly improved on the whole the utilance of frequency spectrum.
Thought based on cognitive radio, is applied in OFDM (Orthogonal Frequency Division Multiplexing, OFDM) system and goes, and parton carrier wave will be taken by primary user, and frequency spectrum is no longer available continuously.According to this feature, discontinuous OFDM (Non-Contiguous Orthogonal Frequency Division Multiplexing, NC-OFDM) by unappropriated subchannel, carry out transfer of data, and the interference to primary user is avoided in the subcarrier zero setting corresponding to occupied subchannel.
As the OFDM technology in Multicarrier Transmission Technology have the availability of frequency spectrum high, realize simple, be easy to carry out the advantages such as combination with other technology, thereby be extensively subject to the favor of scientific research and engineering field, and obtain extensively popularization as the key technology of 4G.But OFDM technology also has some defects of self, one of subject matter that wherein too high peak-to-average power ratio (Peak-to-Average Power Ratio, PAPR) is the application of restriction ofdm system engineering.
The time domain output of ofdm system shows as the stack of a plurality of sub-carrier signals, certainly will cause like this composite signal can produce very high PAPR, and this linearity to transmitter power amplifier has proposed very high requirement, has increased the required precision of equipment.Too high power also can cause very large waste simultaneously, and the next generation communication system requiring with high energy efficiency runs in the opposite direction.
For this problem, a lot of scholars are studied, the method of various reduction ofdm system PAPR has been proposed, wherein, document 1 " High-throughput, high-performance OFDM via pseudo-orthogonal carrier interferometry spreading codes (W.D A, Nassar C R and Z.Wu.IEEE Transactions on Communications, vol.51, iss.7, 1123-1134, July 2003) " a kind of CI-OFDM transmission technology proposed, it utilizes a kind of CI code of quadrature, each parallel data of transmitting on subcarrier is individually expanded on all subcarriers and transmitted simultaneously, the peak value of each subcarrier time domain waveform of modulation is evenly staggered, as OFDM time domain waveform, be no longer that signal by all subcarriers is formed by stacking, thereby make between subcarrier transmitted power in theory identical, thereby reduced the PAPR of transmitted signal.
Document 2 " research of carrier wave interference ofdm system signal detection technique (high training. Chengdu: University of Electronic Science and Technology 2011.) " CI-OFDM technology is applied in the discontinuous available situation of subcarrier, design a kind of CI code adding method, proposed discontinuous CI-OFDM system.But this method is only carried out CI expansion to data subcarrier, the existence of the idle sub-carrier causing due to primary user, makes the orthogonality of subcarrier be subject to destruction to a certain degree, and the amplitude that causes PAPR to suppress is less.
Summary of the invention
The present invention proposes a kind of discontinuous available subcarrier CI-OFDM code adding method, described method is carried out CI expansion to data subcarrier and idle sub-carrier simultaneously, not only suppressed PAPR problem, and taken into account the orthogonality of subcarrier, the PAPR finally transmitting has obtained greatly and has reduced.
A discontinuous available subcarrier CI-OFDM code adding method, comprises the steps:
S1, obtain spectrum information:
Obtain primary user's information, obtain idle frequency spectrum label vector Λ=[Λ
1, Λ
2..., Λ
n], establishing 0 element number in described idle frequency spectrum label vector Λ is N
zero, wherein, if when i subcarrier is occupied, Λ
i=0, if when i subcarrier is unoccupied, Λ
i=1, N represents the quantity of subcarrier, N
zerorepresenting has N in N frequency
zeroindividual frequency is occupied, and available frequency is N-N
zero, i=1,2 ..., N, N is positive integer;
S2, carry out the expansion of CI code:
According to available frequency N-N described in S1
zeroobtain N-N
zeroindividual modulation signal, described N-N
zerothe idle frequency spectrum vector Λ that individual modulation signal be take described in S1 is index, builds the N dimension frequency domain transmitted signal X before CI expansion, and described signal X is carried out to the expansion of CI code, does the IDFT computing that N is ordered, and obtains signal X
cI, wherein, X
cIn dimensional vector for non-zero;
S3, to occupied sub-carrier positions zero setting, obtain the frequency domain transmitted signal X after the expansion of CI code
fd:
Described in S1, N
zeroindividual subcarrier is occupied, to described N
zeroindividual sub-carrier positions is carried out zero setting, obtains the frequency domain transmitted signal X after CI expansion
fd=Λ X
cI;
S4, carry out OFDM transmission:
By S3 gained frequency domain transmitted signal X
fdmode with OFDM sends.
Further, whole the power that described in S1, N is 2.
Further, as Λ described in S1
i=1 o'clock, with modulation signal described in S2 to X
iassignment, as Λ described in S1
i=0 o'clock, X
i=0, wherein, X
ii the element that represents the N dimensional signal before CI expansion.
The invention has the beneficial effects as follows:
The present invention, with respect to traditional ofdm system transmitter model, has added N point IDFT computing, does not need too many extra complexity and hardware spending.With respect to traditional OFDM, the present invention greatly reduces the PAPR of transmitted signal, makes transmitted signal power division more even, has reduced the design difficulty of transmitter power amplifier.
If whole the power that N is 2, with respect to traditional ofdm system transmitter model, only need to add the IFFT computing that a N is ordered, lower with respect to IDFT computational complexity.
The present invention proposes adding N
zeron dimensional signal after individual 0 carries out CI expansion, with respect to prior art directly to N-N
zeromodulation symbol carries out CI expansion, has kept the orthogonality of subcarrier, makes the PAPR transmitting obtain further reduction.
Accompanying drawing explanation
Fig. 1 is transmitter block diagram of the present invention.
Fig. 2 is specific embodiment simulation result figure.
Embodiment
Below in conjunction with embodiment and accompanying drawing, describe technical scheme of the present invention in detail.
Present embodiment adopts Matlab2013a emulation platform to carry out running experiment.Ofdm system parameter: subcarrier N=1024, Cyclic Prefix N
p=128, sampling time T
s=0.1us.The shared subcarrier of primary user accounts for 20% of total number of sub-carriers, and the shared sub-carrier number of primary user is N
zero=N * 20%.
Modulation system is QPSK modulation, and coded system adopts 1/2 convolution code, and the shared subcarrier of primary user accounts for 20% of total number of sub-carriers, the Random assignment of primary user position.
Step 1: structure idle frequency spectrum label vector Λ.A N dimensional vector of random generation, guaranteeing has N in vector
zeroindividual 0, N-N
zeroindividual 1.
Step 2: according to idle frequency spectrum label vector Λ, by the N-N receiving
zeroindividual modulated signal is expanded into N dimensional vector X, works as Λ
i=1 o'clock, with modulated signal to X
iassignment; Work as Λ
i=0 o'clock, X
i=0.Wherein, i=1,2 ..., N, N is positive integer.
The N dimensional vector X obtaining is carried out to CI expansion, picked up signal X
cI.
Step 3: occupied sub-carrier positions zero setting.Be about to step 2 gained vector X
cIΛ multiplies each other with idle frequency spectrum label vector.
Step 4: the signal that step 3 is obtained carries out OFDM transmission.
The PAPR of transmitted signal is carried out to emulation testing, and simulation result as shown in Figure 2.Wherein solid line is for adopting the PAPR distribution function curve transmitting of transmitter schemes that the present invention carries, the PAPR distribution function curve transmitting of the method that dotted line proposes for employing document 2.The symbolic number of emulation is 100000.
Relatively two curves are known, the method that the transmitter schemes that the present invention introduces is compared document 2 propositions has lower PAPR, on distribution curve, have performance gain more than 3dB, and the transmitter schemes that the present invention introduces is compared with document 2 methods on computational complexity basically identical.
One of ordinary skill in the art will appreciate that realizing all or part of step that above-described embodiment method carries is to come the hardware that instruction is relevant to complete by program, described program can be stored in a kind of computer-readable recording medium, this program, when carrying out, comprises step of embodiment of the method one or a combination set of.
In addition, each functional unit in embodiments of the present invention can adopt the form of hardware to realize, and also can adopt the form of software function module to realize.If described integrated module usings that the form of software function module realizes and during as production marketing independently or use, also can be stored in a computer read/write memory medium.
The above-mentioned storage medium of mentioning can be read-only memory, disk or CD etc.
Claims (3)
1. a discontinuous available subcarrier CI-OFDM code adding method, is characterized in that, comprises the steps:
S1, obtain spectrum information:
Obtain primary user's information, obtain idle frequency spectrum label vector Λ=[Λ
1, Λ
2..., Λ
n], establishing 0 element number in described idle frequency spectrum label vector Λ is N
zero, wherein, if when i subcarrier is occupied, Λ
i=0, if when i subcarrier is unoccupied, Λ
i=1, N represents the quantity of subcarrier, N
zerorepresenting has N in N frequency
zeroindividual frequency is occupied, and available frequency is N-N
zero, i=1,2 ..., N, N is positive integer;
S2, carry out the expansion of CI code:
According to available frequency N-N described in S1
zeroobtain N-N
zeroindividual modulation signal, described N-N
zerothe idle frequency spectrum vector Λ that individual modulation signal be take described in S1 is index, builds the N dimension frequency domain transmitted signal X before CI expansion, and described signal X is carried out to the expansion of CI code, does the IDFT computing that N is ordered, and obtains signal X
cI, wherein, X
cIn dimensional vector for non-zero;
S3, to occupied sub-carrier positions zero setting, obtain the frequency domain transmitted signal X after the expansion of CI code
fd:
Described in S1, N
zeroindividual subcarrier is occupied, to described N
zeroindividual sub-carrier positions is carried out zero setting, obtains the frequency domain transmitted signal X after CI expansion
fd=Λ X
cI;
S4, carry out OFDM transmission:
By S3 gained frequency domain transmitted signal X
fdmode with OFDM sends.
2. a kind of discontinuous available subcarrier CI-OFDM code adding method according to claim 1, is characterized in that: whole the power that described in S1, N is 2.
3. a kind of discontinuous available subcarrier CI-OFDM code adding method according to claim 1, is characterized in that: as Λ described in S1
i=1 o'clock, with modulation signal described in S2 to X
iassignment, as Λ described in S1
i=0 o'clock, X
i=0, wherein, X
ii the element that represents the N dimensional signal before CI expansion.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060227851A1 (en) * | 1998-02-12 | 2006-10-12 | Steve Shattil | Multiple access method and system |
| CN101217526A (en) * | 2008-01-17 | 2008-07-09 | 中兴通讯股份有限公司 | An OFDM system carrier interference noise ratio measurement method |
| CN101692664A (en) * | 2009-10-13 | 2010-04-07 | 清华大学 | Multi-carrier wireless transmission method for adopting discontinuous carrier wave interference code |
| CN101848175A (en) * | 2009-03-24 | 2010-09-29 | 华为技术有限公司 | Methods and devices for pilot signal transmitting and pilot signal-based channel estimation |
| CN101917252A (en) * | 2010-08-06 | 2010-12-15 | 电子科技大学 | Zero padding mode-based CI-OFDM communication method |
-
2014
- 2014-08-25 CN CN201410422164.3A patent/CN104202284A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060227851A1 (en) * | 1998-02-12 | 2006-10-12 | Steve Shattil | Multiple access method and system |
| CN101217526A (en) * | 2008-01-17 | 2008-07-09 | 中兴通讯股份有限公司 | An OFDM system carrier interference noise ratio measurement method |
| CN101848175A (en) * | 2009-03-24 | 2010-09-29 | 华为技术有限公司 | Methods and devices for pilot signal transmitting and pilot signal-based channel estimation |
| CN101692664A (en) * | 2009-10-13 | 2010-04-07 | 清华大学 | Multi-carrier wireless transmission method for adopting discontinuous carrier wave interference code |
| CN101917252A (en) * | 2010-08-06 | 2010-12-15 | 电子科技大学 | Zero padding mode-based CI-OFDM communication method |
Non-Patent Citations (1)
| Title |
|---|
| 高培: "载波干涉OFDM系统信号检测技术研究", 《中国优秀硕士论文全文数据库信息科技辑》 * |
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Application publication date: 20141210 |