WO2010121415A1

WO2010121415A1 - Modulating method and modulating equipment for ofdm signal

Info

Publication number: WO2010121415A1
Application number: PCT/CN2009/071376
Authority: WO
Inventors: 姜勇; 王艺
Original assignee: 华为技术有限公司
Priority date: 2009-04-21
Filing date: 2009-04-21
Publication date: 2010-10-28
Also published as: CN102439929A; CN102439929B

Abstract

A modulating method and modulating equipment for Orthogonal Frequency Division Multiplexing (OFDM) signal are provided by the embodiments of the invention in the wireless communication filed. The method includes: receiving the current OFDM signal and the previous OFDM signal or the adjusted previous signal; generating a noise signal according to the received signal; superposing the noise signal to the current OFDM signal and generating an adjusted current OFDM signal; wherein the cyclic prefix of the adjusted current OFDM signal and the end of the previous OFDM signal or the end of the adjusted previous OFDM signal are continuous.

Description

Modulation method and modulation device for OFDM signal

Embodiments of the present invention relate to the field of wireless communications, and in particular, to a modulation method and a modulation apparatus for an OFDM signal.

Background technique

With the growth of users' demand for various real-time multimedia services and the rapid development of Internet technologies, higher and higher requirements are placed on the information transmission rate of wireless communications. In order to support higher information transmission rates and higher user movement speeds, in the next generation wireless communication systems, wireless transmission technologies with higher spectral efficiency and greater resistance to multipath interference must be used.

Among the current wireless schemes for high-rate transmission, multi-carrier modulation technology represented by OFDM (Orthogonal Frequency Division Multiplexing) has become one of the most popular technologies. Multi-carrier modulation techniques typically employ such carrier modulation: Decompose the data stream into thousands of relatively low-rate sub-streams, and use the low-rate multi-state signals formed by the low bit rates in these sub-streams to modulate the corresponding Subcarriers, thereby constituting a transmission system in which a plurality of low rate signals are transmitted in parallel.

OFDM has the following advantages: It can effectively resist inter-signal interference caused by multipath; it can effectively resist narrowband interference; on a channel with relatively slow change, OFDM system can optimize allocation according to the signal-to-noise ratio of each subcarrier. The information bits transmitted on the subcarriers improve the effective capacity of the system to transmit information; the modulation and demodulation can be realized by fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT), and the implementation complexity is low.

In order to combat Inter-Symbol Interference (ISI) caused by multipath effects, OFDM technology uses a guard interval (GI) before each OFDM signal. In a specific system implementation, the protection interval is usually filled with a Cyclic Prefix (CP), which is called CP-OFDM. CP-OFDM technology can overcome both ISI and Inter-carrier Interference (ICI). At present, existing OFDM systems and standards are basically based on CP-OFDM technology. One disadvantage of OFDM signals is that the out-of-band attenuation of the power spectrum is not fast enough to cause interference with adjacent band data. At present, the scheme of time domain windowing is usually used to perform out-of-band power suppression, but it is easy to reduce the anti-ISI and ICI capabilities of the CP-OFDM system.

Summary of the invention

Embodiments of the present invention provide a modulation method and a modulation apparatus for an OFDM signal, which can improve an out-of-band attenuation rate of a power spectrum and enhance the anti-ISI and ICI capabilities of OFDM.

Embodiments of the present invention adopt the following technical solutions:

Embodiments of the present invention provide a modulation method for an OFDM signal, including:

Receiving a current OFDM signal and a previous OFDM signal or an adjusted previous OFDM signal;

Generating a noise signal based on the received signal;

Superimposing the noise signal on the current OFDM signal to generate an adjusted current OFDM signal, where the CP of the adjusted current OFDM signal is continuous with a tail of the previous OFDM signal or the adjusted previous OFDM signal .

An embodiment of the present invention provides another modulation method for an OFDM signal, including: acquiring a current OFDM signal to which a CP is added, a previous OFDM signal to which a CP is added, and a previous OFDM signal to which a first noise signal is superimposed;

Generating a second noise signal of the previous OFDM signal according to the current OFDM signal to which the CP is added and the previous OFDM signal superimposed with the first noise signal; superimposing the second noise signal on the superimposed Generating an adjusted previous OFDM on a previous OFDM signal of a noise signal;

Generating a first noise signal of a current OFDM signal according to the current OFDM signal to which the CP is added and the previous OFDM signal to which the CP is added, and superimposing the first noise signal on the current OFDM signal to generate The current OFDM signal of the first noise signal is superimposed, and the CP of the current OFDM signal superimposed with the first noise is continuous with the tail of the adjusted previous OFDM signal.

An embodiment of the present invention provides a modulation apparatus for an OFDM signal, including: a receiving unit, configured to receive a current OFDM signal and a previous OFDM signal or an adjusted previous OFDM signal;

a noise generating unit, configured to generate a noise signal according to the received signal;

a signal generating unit, configured to superimpose the noise signal on the current OFDM signal, to generate an adjusted current OFDM signal, and the adjusted CP of the current OFDM signal and the previous OFDM signal or the adjusted upper The tail of an OFDM signal is continuous.

An embodiment of the present invention provides another modulation apparatus for an OFDM signal, including: an obtaining unit, configured to acquire a current OFDM signal to which a CP is added, a previous OFDM signal to which a CP is added, and a previous one to which a first noise signal is superimposed OFDM signal;

a noise generating unit, configured to generate a second noise signal of a previous OFDM signal according to the current OFDM signal to which the CP is added and the previous OFDM signal to which the first noise signal is superimposed; and superimpose the second noise signal Generating an adjusted previous OFDM on the previous OFDM signal on which the first noise signal is superimposed;

a signal generating unit, configured to generate a first noise signal of a current OFDM signal according to the current OFDM signal to which the CP is added and the previous OFDM signal to which the CP is added, and superimpose the first noise signal on A current OFDM signal on which the first noise signal is superimposed is generated on the current OFDM signal, and a CP of the current OFDM signal superimposed with the first noise is continuous with a tail of the adjusted previous OFDM signal.

The modulation method and the modulating apparatus of the OFDM signal provided by the embodiment of the present invention, by superimposing the noise signal on the current OFDM signal, so that the adjusted CP of the current OFDM signal is continuous with the tail of the previous OFDM signal, or the adjusted current is made The CP of the OFDM signal is continuous with the tail of the adjusted previous OFDM signal, and the first few samples of the CP of the adjusted current OFDM signal can also be regarded as the cyclic suffix of the previous OFDM modulated signal, and the OFDM signal is realized. The continuous, effective suppression of out-of-band leakage enhances the ability of OFDM to resist ISI and ICI. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art description will be briefly described below, obviously, the following The drawings in the description are only some of the embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative work.

1 is a schematic flow chart of Embodiment 1 of the present invention;

2 is a schematic flow chart of Embodiment 2 of the present invention;

3 is a schematic diagram of an OFDM signal according to Embodiment 2 of the present invention;

4 is a schematic diagram of another OFDM signal according to an embodiment of the present invention;

FIG. 5 is a schematic flowchart of Embodiment 3 of the present invention; FIG.

6 is a schematic flow chart of Embodiment 4 of the present invention;

Figure Ί is a schematic flowchart of Embodiment 5 of the present invention;

8 is a schematic flow chart of Embodiment 6 of the present invention;

9 is a schematic flow chart of Embodiment 7 of the present invention;

Figure 10 is a schematic diagram of a modulation apparatus for OFDM according to an embodiment of the present invention;

11 is a schematic diagram of a noise generating unit according to an embodiment of the present invention;

FIG. 12 is a schematic diagram of a modulation apparatus for OFDM according to another embodiment of the present invention; FIG.

FIG. 13 is a schematic diagram of a noise generating unit according to another embodiment of the present invention.

Detailed ways

A modulation method and a modulation apparatus for an OFDM signal according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

It should be understood that the described embodiments are only a part of the embodiments of the invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention. The following embodiments are all optional of the present invention, and the order of arrangement of the following embodiments does not indicate a priority order.

Embodiment 1

As shown in FIG. 1, an embodiment of the present invention provides a method for modulating an OFDM signal, including: S101: receiving a current OFDM signal and an adjusted previous OFDM signal;

In the present application, the adjusted last OFDM signal refers to the last OFDM signal on which the noise signal is superimposed. 5102. Generate a noise signal according to the received signal.

5103. Superimpose the noise signal on the current OFDM signal to generate an adjusted current OFDM signal, where the adjusted CP of the current OFDM signal is continuous with a tail of the adjusted previous OFDM signal.

The OFDM signal modulation method provided by the embodiment of the present invention implements continuous and effective OFDM signals by superimposing a noise signal on the OFDM signal so that the adjusted CP of the current OFDM signal is continuous with the adjusted previous OFDM signal. It suppresses out-of-band leakage and enhances the anti-ISI and ICI capabilities of OFDM.

Embodiment 2

As shown in FIG. 2, this embodiment may include the following steps:

S201. Receive an ith OFDM signal and an adjusted Lith OFDM signal.

After the first ^¾ 'th OFDM signal is referred Adjustment z' th OFDM signal is called adjustment of OFDM signals as -1, it can be extracted from the cache.

That is, after each OFDM signal superimposed with a noise signal is obtained, it is buffered, and step S206 is referred to. The OFDM signal on which the noise signal is superimposed can be regarded as an adjusted OFDM signal.

S202. Acquire a pulse-like Kernel signal corresponding to the i-th OFDM signal.

Specifically, the Kernel signal is generated as follows:

First, a suitable weight value ^ is set for each carrier of the OFDM signal, which must satisfy ^ ^{≥ Q} and be a non-negative real number, and then perform an IFFT transform to obtain a Kernel signal. The Kernel signal normalized for the highest amplitude of M-time rate oversampling is:

Wherein, the number of samples corresponding to the OFDM signal of the double rate, / is the index value of the time domain sample corresponding to the OFDM signal, is an integer, and 0 ≤ / ≤ ΜΚ-1, & is the frequency domain corresponding to the OFDM signal The index value of each carrier is an integer, and 0 ≤ it ≤ MK - 1. Find the magnitude of _Pl according to formula (2):

=1,

In the above formula, the condition that the equal sign is established is that the elements of the summation are superimposed in the same phase, that is, different

, 2τΜ

When the value is ¹ ^ dish are in phase. For the weight vector there must be two consecutive elements greater than 0 and

.2πΜ

In order to ensure that ^ ^MK and ^ ^{e MK} are in phase, ^^ ^MK " is required to be a positive real number, so only 0 is established.

That is, 3⁄4 ^{= 1} is the highest amplitude point of the Kernel signal, and the other points are all smaller than 1.

The process of generating the Kernel signal may not be performed online, for example, by computer generation, and may be directly extracted when needed.

When generating a Kernel signal, the distribution of noise on each subcarrier can be flexibly controlled by different weight settings. For example, if the weight is set only on a specific subcarrier, and the other subcarriers are set to a weight of 0, the noise introduced by the embodiment of the present invention only falls on these specific subcarriers; and may also be on the subcarriers with strong anti-interference capability. Set a larger weight value, set a smaller weight value on the subcarrier with less anti-interference ability, and set the weight value to 0 on the important or non-interfering subcarrier. The embodiment of the present invention can be used once. Large noise is introduced on subcarriers with strong anti-interference ability, and small noise is introduced on subcarriers with poor anti-interference ability. No significant noise is introduced on subcarriers that are not interfered with.

Let N be a positive integer. In this embodiment, the first N samples of the CP after the current OFDM signal is superimposed with the noise signal are the same as the first N samples of the previous OFDM modulation signal. The complete M-time oversampled Kernel signal is the MK sample pattern shown in equation (1). The N*N point matrix in this embodiment represents the N different cyclic shift Kernel signals. A matrix of N samples near _Po .

Among them, each column represents N samples of the MK-Tg+1 to MK-Tg+N in a total of MK samples of a different cyclically shifted Kernel signal (N is smaller than CP length Tg).

The Kernel signal p is represented by ρ _{τ and} the cyclic shift of r is performed, that is, r = (P _MK - Ρ _ΜΚ - _{τ +} ι · · · PMK-I ) A... PHI). Then, the cyclically shifted Kernel signal vector corresponding to the first column in the N*N dot matrix can be expressed as ^Pm ^ ^{= (/} ^{3⁄4 Ρτ} '" ^Ρμκ ~ ^{1 Ρο Ρι} '" ^Ρτ ^ ^ι, the vector has MK elements, wherein N samples from MK-Tg+1 to MK-Tg+N are [Po Pi

That is, the first column element of the above N*N matrix. Similarly, the second column element in the N*N dot matrix is Ρ _Μί — ₊₁ = P _TG+ 2•••PMK-I P. N samples of MK-Tg+1 to MK-Tg+N in A...; \), that is, p ₀ ～ 1⁄2_ ₂ ]. Similarly, you can recurse to the Nth column element.

S203. Obtain an amplitude phase adjustment coefficient corresponding to each of the N different cyclically shifted Kernel signals according to the i-th OFDM signal and the adjusted first-one OFDM signal.

When = 0, S° = s°, that is, the first time domain OFDM signal does not have to be adjusted. When z'≥l, it is necessary to satisfy the 'signal addition CP', the first W samples of the CP are exactly equal to the adjusted first; the cyclic suffix of the -1 OFDM signal ¹ is equal, or it can be said that the first W are equal to ¹ The samples are equal, that is:

Where T _g is the CP length of the first OFDM signal. The amplitude phase adjustment coefficient corresponding to each Kernel signal of the first OFDM signal can be derived from equation (3) to ^c :

(4). The above is the continuous taking of the current signal. The first w samples of the CP as the front of the symbol are equal to the previous sample of the previous signal. It is also possible to take these equal samples discontinuously. For example, when only two consecutive points are taken, the first and second points may be discontinuously taken, and the first and third points are equal to the corresponding samples of the previous signal. In this example, equation (3) becomes:

Therefore, the amplitude phase adjustment coefficient is pushed,

S204. Generate a noise signal according to the N Kernel signals and the corresponding amplitude phase adjustment coefficients, and the connection process may be expressed as:

Cn ― c ₀ 'P _MK _ _Tg + c _x ·ρ _ΜΚ _ _τ ^ _+ι Η \- c _N _ · _ΜΚ _ _τ ^ _+Ν _ _ι

(7) That is, the noise signal is the superposition of W cyclically shifted Kernel signals with amplitude phase adjustments to the amplitude phase adjustment coefficients corresponding to the N different cyclically shifted Kernel signals of the i-th signal.

The superimposed signals corresponding to the discontinuous equal points shown in equations (5) and (6) are

Cn = c _Q ·ρ _MK _ _Tg + c ₂ - p _MK —T _G +2 (8)

5205. Superimpose the noise signal on the !' OFDM signal to generate an adjusted first OFDM signal. That is:

= s'' + cn (9)

5206. Cache the adjusted ith OFDM signal for the +1 OFDM signal The modulation of the number is used, as shown by the dotted line in Figure 2.

The present invention is not limited thereto, and only the first N samples of the adjusted first OFDM signal may be buffered. And in the modulation of _ζ · + 1 th OFDM signal, step S201 may be acquired only the first N samples th OFDM signal after the adjustment process.

S207. Add a CP to the adjusted first OFDM signal, and output.

After the CP is added to the adjusted ith OFDM signal, the first few samples of the CP are exactly equal to the first samples of the adjusted z'-l OFDM signals before the CP is added, so that the signals are continuous. Reduced leakage of out-of-band power. As shown in FIG. 3, the CP of the first OFDM signal, that is, the first N samples of CPi, that is, the A part shown in the figure, and the first N samples of the z'-l OFDM signal before the CP is added. The point, that is, the part B shown in the figure is the same.

As shown in Figure 3, the length of the adjusted CPi is larger than the CPi of the original OFDM, and it can be seen that the length of the effective CP increases from 7 to 7 +N. Thus, embodiments of the present invention increase the effective CP length while effectively suppressing out-of-band leakage, thereby enhancing the ability to resist ISI and ICI.

As shown in FIG. 4, N samples before the CP portion to be extracted in the OFDM signal, that is, the C portion shown in the figure, and the N samples at the tail of the first OFDM signal may be used. Part B shown in the same is the same. Since the C portion is continuous with the subsequent samples, the B portion is also continuous with the samples after the C portion. After the CP is added to the first OFDM signal, the added CP is continuous with the tail of the first OFDM signal. In this way, the adjusted i-th OFDM signal and the adjusted first OFDM signal can also be made continuous.

Embodiment 3

As shown in FIG. 5, this embodiment may include the following steps:

5501. Receive a current OFDM signal and a previous OFDM signal.

S502: Generate a noise signal according to the received signal.

S503. The noise signal is superimposed on the current OFDM signal to generate an adjusted current OFDM signal. The CP of the adjusted current OFDM signal is continuous with a tail of the previous OFDM signal.

By superimposing the noise signal on the current OFDM signal, the CP of the pre-OFDM signal is compared with The tail of one OFDM signal is continuous, which can effectively suppress out-of-band leakage and enhance the anti-ISI and ICI capabilities of OFDM.

Embodiment 4

As shown in FIG. 6, the embodiment may include the following steps:

5601. Receive a first OFDM signal, and add a CP to the first OFDM signal.

The first OFDM signal to which the _{CP is added is} represented by S ^l _CP .

5602. Receive a first-one OFDM signal to which a CP is added. The first OFDM signal to which the CP is added can be obtained from the cache.

S603. Acquire a Kernel signal corresponding to the i-th OFDM signal.

Let N be a positive integer. In this embodiment, the first N samples of the CP after the current OFDM signal is superimposed with the noise signal are the same as the first N samples of the previous OFDM modulated signal. The complete M-time oversampled Kernel signal is the MK sample pattern shown in equation (1). The N*N point matrix in this embodiment represents the N different cyclic shift Kernel signals. A matrix of N samples near p ₀ .

Wherein each column represents N samples of the first to N of the approximately half of the samples from the left of a different cyclically shifted Kernel signal (N is less than the CP length Tg). If p ^{/ f is used to} represent the Kernel signal p, about half of the samples on the left side after the cyclic shift of r are performed, and the remaining samples are set to zero, that is,

≠ = V _MK - Ρ _Μ κ_ _τ+ ι · · · PMK-I O PI ... PMKII-I . 0 ... 0]. then

MKIl-τ 0

The cyclically shifted Kernel signal vector corresponding to the first column in the N*N point matrix can be expressed as P = [P ₀ A ... P _{MK I} w 0 0 · · · 0], which has MK elements, of which 1

MK/2 0

The N samples to N are [p. / Pn] , which is the first column element of the above N*N matrix. Similarly, the second column element in the N*N point matrix is

N of the first to N in PO PI ... PMKI 2-I ^{0 0} ... 0]

MK / 2—1 0

Sample point, that is, [ρ _Μ ^ Po Α ' · · Αν_ ₂ ]. Similarly, you can recurse to the third column element. S604. Acquire an amplitude phase adjustment coefficient corresponding to a Kernel signal of different cyclic shifts according to the first OFDM signal to which the CP is added and the first OFDM signal to which the CP is added.

s

The first N samples of the first OFDM modulated signal, ie " ³ , °," ... ^Λ «^- with

! - 1 c !'-1

The first N samples of the OFDM signal of the _CP , namely ⁵ _CP τ , ^s cp, T _e +l ......

If the same is required, the CP of the adjusted first OFDM signal and the tail of the first OFDM signal are continuous to achieve continuity between the signals. Then, the calculation formulas of the amplitude phase adjustment coefficients corresponding to the N Kernel signals are as follows:

1

(9)

One 1

~ C

₀ 'one ¹ -

―

c\ Pi Po ' ♦♦ PMK-N+2 CP, T _g +l

Two -

(10)

_ ^L W- 1— _PN-I PN-2 ' ·· Po _ CP, T _G +N-1 CP, Nl

5605. Generate a noise signal according to the Kernel signal and the corresponding amplitude phase adjustment coefficient, to obtain a noise signal cn' _{CT of the} first OFDM signal:

Cn^ = 4 - ^ +c; ·ρ ^10...+ ^^ ·ρ?ί ( 11 )

5606, noise signal obtained in step S605 is added on the superimposed th OFDM signal CP, generates and outputs the first add ^¾ 'th OFDM signal CP is adjusted.

^CP ― ^CP cp ( 12 )

The first N samples of the adjusted first OFDM signal are the same as the first N samples of the first OFDM signal without the CP, or the adjusted i-th OFDM modulation signal. The number and the tail of the L i OFDM signals are continuous. Since the samples in the middle tail are set to 0, the noise signal is only superimposed on the front of the first OFDM signal, and there is no change in the tail.

Since the Kernel signal used in this embodiment is 0 after the sample points, the noise signal is also 0 in the second half, and the tail of the previous OFDM signal is equal to the tail of the adjusted previous OFDM signal; That is, if the CP of the current OFDM signal is continuous with the tail of the previous OFDM signal, the CP of the current OFDM signal and the tail of the adjusted previous OFDM signal are also continuous.

S607. Cache the first OFDM signal to which the CP is added to provide modulation for the +1st OFDM signal. This step can also be after S601 or other steps.

In this embodiment, the continuation of the adjusted first OFDM signal and the L i OFDM signal is implemented, thereby suppressing out-of-band power leakage and enhancing the ability to resist ISI and ICI.

Embodiment 5

As shown in FIG. 7, the embodiment may include the following steps:

S701. Receive the ith OFDM signal and the adjusted first OFDM signal.

S702. Acquire an ideal noise signal according to a difference between the first OFDM signal and the adjusted first one OFDM signal.

The adjusted first OFDM signal can be obtained from the cache. The ideal noise signal cn is a difference signal between the first few samples of the CP portion in the current OFDM signal and the first few samples of the adjusted L l OFDM signals. The formula is expressed as:

MK-N〇

(12)

5703. Perform FFT transformation on the ideal noise ^c dl to the frequency domain.

5704. Perform weight adjustment on the frequency domain signal of the ideal noise signal ^cn Lfe«z according to the weight of each subcarrier corresponding to the i-th OFDM signal, and transform back to the time domain to obtain an approximate noise signal of the ideal noise signal. Ci _e . _;0 .

Here, the weight of each subcarrier is different, and the weight of the Kernel signal of the second embodiment is adjusted. The whole principle is consistent.

_{5705. Adjusting} an amplitude of an approximate noise signal cn _flK) of the ideal noise signal to obtain a noise signal cn'

Amplitude adjustment is performed on the approximate noise signal cn^ _eart) converted back to the time domain by S704 to obtain a noise signal cn. Specifically, the amplitude of the time domain noise signal can be adjusted according to the energy of the first N samples or according to the highest amplitude.

S706: The noise signal ^cn obtained by S705 is superimposed to the first, and the adjusted first OFDM signal is generated on the 'OFDM signals.

5707. Add a CP to the adjusted first OFDM signal, and output.

5708, after adjusting the first _z 'th OFDM modulated signal is cached for use of _ζ · + 1 th OFDM signal.

Embodiment 6

As shown in FIG. 8, an embodiment of the present invention provides another modulation method for an OFDM signal, which may include the following steps:

5801. Obtain a current OFDM signal to which the CP is added, a previous OFDM signal to which the CP is added, and a previous OFDM signal to which the first noise signal is superimposed;

5802. Generate a second noise signal of a previous OFDM signal according to the current OFDM signal to which the CP is added and the previous OFDM signal to which the first noise signal is superimposed; and superimpose the second noise signal on the superposition Generating the adjusted previous OFDM on the previous OFDM signal of the first noise signal;

5803. Generate a first noise signal of a current OFDM signal according to the current OFDM signal to which the CP is added and the previous OFDM signal to which the CP is added, and superimpose the first noise signal on the current OFDM signal. And generating a current OFDM signal superimposed with the first noise signal, wherein the CP of the current OFDM signal superimposed with the first noise is continuous with the tail of the adjusted previous OFDM signal.

In the sixth embodiment and the seventh embodiment, the previous OFDM signal on which the first noise signal and the second noise signal are superimposed is referred to as an adjusted previous OFDM signal. In this embodiment, by superimposing the first noise signal and the second noise signal on the OFDM signal, the CP of the current OFDM signal superimposed with the first noise is continuous with the tail of the adjusted previous OFDM signal, thereby suppressing out-of-band power. Leakage enhances the ability to resist ISI and ICI.

Example 7

As shown in FIG. 9, the embodiment may include the following steps:

S901. Acquire a first OFDM signal to which the CP is added, a first OFDM signal to which the CP is added, and a first to first OFDM signal to which the first noise signal is superimposed.

The Mth OFDM signal to which the CP is added and the 1st OFDM signal to which the first noise signal is superimposed may be acquired from a buffer. Wherein the first noise superimposed th OFDM signal is added on the second CP of OFDM signals _ζ · -1 superimposed first noise signal generated.

S902a, generating a second kernel signal.

The second kernel signal is generated according to the weight of each subcarrier in the first OFDM signal, and the specific generation scheme is the same as the step in S202 of the second embodiment. The N*N dot matrix in this embodiment represents a matrix of N samples near the _Po of N different cyclically shifted Kernel signals, as follows:

Wherein each column represents the last N samples (N is less than the CP length Tg) of about half of the samples from the right side of a different cyclically shifted Kernel signal. If p ^ is used to represent the Kernel signal p, about half of the samples on the right side after the cyclic shift, the other samples are set to zero, where r is greater than or equal to

MK-N, ie P = [0 0 · · · 0 PMK/2 PMK! 2A ■■■ PMK-I PO PI ■■■ PuK--λ„

ΜΚ/2-τ 0

Then, the cyclically shifted Kernel signal vector corresponding to the first column in the N*N point matrix can be expressed as PMI-I = [Q Q · " Q PMK/2 PM ... PMK-I ], which has MK elements.

MKI2-X 0

The last N samples are

PMK-N ₊ 2 · · · 3⁄4], which is the first column element of the above N*N matrix. Similarly, the second column element in the N*N point matrix is

VMK-2 = the last N samples in [QQ · "Q PMK/2 PMK/2 ₊ I ... PMK-I PO A],

ΜΚ/2-τ 0 That is, [ 3⁄4/r- _W+ 2 ·'·Ρο A]. Similarly, you can recurse to the Nth column element.

S902b. Generate a first Kernel signal.

The first kernel signal is generated according to the weight of each subcarrier in the current OFDM signal, and the specific generation scheme is the same as the step in S202 of the second embodiment. The N*N dot matrix in this embodiment represents a matrix of N samples near the _Po of N different cyclically shifted Kernel signals, as follows:

P N-1 Po

S903a obtains an amplitude phase adjustment coefficient corresponding to each of the N second Kernel signals according to the first OFDM signal added with the CP and the first OFDM signal superimposed with the first noise

¹ ,

2, the following formula (13) is based on the last N samples of the ί·-1 OFDM modulated signal, and the N samples before the CP of the ith OFDM signal to which the CP is added and superimposed The principle that the average of the tail of a noise-first OFDM signal is equal to the average of a sample point is obtained. Wherein, N samples before the CP of the first OFDM signal to which the CP is added are used for S ¹ CP, MK-N, s, CP, , MK-N+l

Representing the N samples of the tail of the -1st OFDM signal superimposed with the first noise

~― 1 ― 1 main one

CP MK+T _g -N, ^S CPXMK^T _G -N ₊ \ ^S CP MK+T _g -\ table.

S903b: Obtain an amplitude phase adjustment coefficient corresponding to each of the N first Kernel signals according to the first OFDM signal added with the CP and the first OFDM signal to which the CP is added, ^ ... c _N '_ _u . Specifically, the first N samples of the first OFDM signal to which the CP is added are: >. , P, I... sc'p' , the first N samples of the first OFDM signal are:

The right side of the equation of equation (15) is continuous with the right side of the equation of equation (13), because the N samples of the right side of equation (13) are located before the CP of the first OFDM signal to which the CP is added, and the equation (15) On the right side of the CP, the first N samples of the 'OFDM signal are consecutive; the N samples of the ί-l OFDM signal superimposed with the first noise on the right side of equation (13) and the equation (15) The first N samples of the ί-l OFDM signal before adding the CP are consecutive. One

05-(s +s ^l )

(15)

G5.i — ¹ +s ^l )

CP, T _g +N-1 ^ ^ CP, Nl ) i -1 il

^C 0, 1 Po PMK-I · • · ΡΜΚ-Ν-Ι 0.5 -(5 s

i i-l

Cu 0.5 ·

= Pi Po ' • · PMK-N+2 0 CP,T _g +l ^S CP, 1 )

(16) i -1

^C N-\, 1 _PN-I PN-2 · · Po ― 0.5-0 s

· CP, N-l

S904a. Generate a second noise signal of the ^-1th OFDM signal according to the second Kernel signal and the corresponding amplitude phase adjustment coefficient.

S904b. Generate a first noise signal of the ^th OFDM signal according to the first Kernel signal and the corresponding amplitude phase adjustment coefficient.

S905a, superimposing the second noise signal on the first OFDM signal to which the first noise is superimposed, and generating the adjusted z'-l OFDM signals, and outputting.

S905b, superimposing the first noise signal on the first OFDM signal, and buffering the signal for modulation of the +1th OFDM signal, as shown by the dashed line in FIG.

In addition to this, it is also necessary to buffer the first OFDM signal to which the CP is added for modulation of the z + 1 OFDM signal.

The embodiment of the present invention realizes the continuity of the OFDM signal by superimposing the first noise signal and the second noise signal on the OFDM signal such that the tail of the adjusted first OFDM signal is continuous with the CP of the adjusted first OFDM signal. , thereby suppressing out-of-band power leakage and enhancing the anti-ISI and ICI capabilities of OFDM. A person skilled in the art can understand that all or part of the process of implementing the above embodiment method can be completed by a computer program to instruct related hardware, and the program can be stored in a computer readable storage medium. In execution, the flow of an embodiment of the methods as described above may be included. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM). As shown in FIG. 10, an embodiment of the present invention provides a modulation apparatus for an OFDM signal, including: a receiving unit 101, configured to receive a current OFDM signal and a previous OFDM signal or an adjusted previous OFDM signal;

The noise generating unit 102 is configured to generate a noise signal according to the received signal;

a signal generating unit 103, configured to superimpose the noise signal on the current OFDM signal to generate an adjusted current OFDM signal, where, if the receiving unit 101 receives the current OFDM signal and the previous OFDM signal, The adjusted CP of the current OFDM signal is continuous with the tail of the previous OFDM signal; if the receiving unit 101 receives the current OFDM signal and the adjusted previous OFDM signal, the adjusted current OFDM The CP of the signal is continuous with the tail of the adjusted previous OFDM signal.

On the basis of the foregoing solution, as shown in FIG. 11, the noise generating unit 102 includes: an obtaining module 1021, configured to acquire a plurality of pulse-like Kernel signals of different cyclic shifts corresponding to the current OFDM signal;

The coefficient generation module 1022 is configured to obtain, according to the current OFDM signal, the amplitude modulating coefficient corresponding to each of the plurality of Kernel signals, and the previous OFDM signal or the adjusted previous OFDM signal;

The noise generating module 1023 is configured to generate the noise signal according to the Kernel signal and a corresponding amplitude phase adjustment coefficient.

The modulating apparatus of the OFDM signal of the embodiment of the present invention may further include: an adding unit and a delay unit. The adding unit is configured to add a CP of the current OFDM signal before or after the noise signal is superimposed. The delay unit is configured to buffer a current OFDM generated by the signal generating unit The modulated signal is provided to the next OFDM signal.

As shown in FIG. 12, an embodiment of the present invention provides another modulation apparatus for an OFDM signal, including:

The obtaining unit 121 is configured to obtain a current OFDM signal to which the CP is added, a previous OFDM signal to which the CP is added, and a previous OFDM signal to which the first noise signal is superimposed;

a noise generating unit 122, configured to generate a second noise signal of a previous OFDM signal according to the current OFDM signal to which the CP is added and the previous OFDM signal superimposed with the first noise signal; and the second noise signal Superimposed on the previous OFDM signal superimposed with the first noise signal to generate an adjusted previous OFDM;

a signal generating unit 123, configured to: generate the first OFDM signal of the current OFDM signal by adding the current OFDM signal to which the CP is added, and the previous OFDM signal to which the CP is added, and superimpose the first noise signal A current OFDM signal on which the first noise signal is superimposed is generated on the current OFDM signal, and a CP of the current OFDM signal superimposed with the first noise is continuous with a tail of the adjusted previous OFDM signal.

As shown in FIG. 13, the noise generating unit 122 includes: an obtaining module 1221, configured to acquire a plurality of second Kernels of different cyclic shifts corresponding to the adjusted previous OFDM signal, And a signal and a plurality of first kernel signals corresponding to the current OFDM signal and equal in number to the second Kernel signal;

The coefficient generation module 1222 is configured to generate, according to the current OFDM signal added with the CP and the previous OFDM signal with the first noise signal added, an amplitude phase adjustment coefficient corresponding to each of the thousands of second Kernel signals, according to the adding Generating the current OFDM signal of the CP and the previous OFDM signal to which the CP is added, and generating an amplitude phase adjustment coefficient corresponding to each of the plurality of first Kernel signals;

The noise generating module 1223 is configured to generate, according to the second Kernel signal and the corresponding amplitude phase adjustment coefficient, a second noise signal of the previous OFDM signal, according to the first Kernel signal and the corresponding amplitude phase adjustment coefficient. The first noise signal of the current OFDM signal.

For the modulation apparatus of the OFDM signal according to the embodiment of the present invention, reference may be made to the adjustment of the above OFDM signal. In the first to seventh embodiments of the method, the modulation of the OFDM signal is completed.

The OFDM signal modulation apparatus provided by the embodiment of the present invention superimposes the noise signal on the OFDM signal, so that the CP of the current OFDM modulated signal is continuous with the tail of the previous OFDM signal, thereby realizing the continuity of the OFDM signal and effectively suppressing the band. The leakage reveals the ability of OFDM to resist ISI and ICI.

The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any change or replacement that can be easily conceived by those skilled in the art within the technical scope of the present invention is All should be covered by the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

Claim

A method for modulating an OFDM signal, comprising:

Generating a noise signal based on the received signal;

Superimposing the noise signal on the current OFDM signal to generate an adjusted current OFDM signal, the adjusted cyclic prefix of the current OFDM signal and the tail of the previous OFDM signal or the adjusted previous OFDM signal continuous.

2. The method according to claim 1, wherein the generating a noise signal according to the received signal is specifically:

Obtaining thousands of pulse-like Kernel signals of different cyclic shifts corresponding to the current OFDM signal;

Obtaining, according to the current OFDM signal, the previous OFDM signal or the adjusted previous OFDM signal, respectively, the amplitude phase adjustment coefficients corresponding to the plurality of Kernel signals;

The noise signal is generated according to the Kernel signal and a corresponding amplitude phase adjustment coefficient.

3. The method according to claim 2, wherein adjacent ones of the plurality of Kernel signals are shifted by one shift;

The noise signal is the sum of the products of the plurality of Kernel signals and the corresponding amplitude phase adjustment coefficients.

The method according to claim 3, wherein the Kernel signal is a one-dimensional vector generated according to weights of respective subcarriers corresponding to the current OFDM signal.

5. The method according to claim 2, wherein if the current OFDM signal and the previous OFDM signal are received, the method further comprises: adding the current OFDM signal after receiving the current OFDM signal Cyclic prefix

After generating the plurality of Kernel signals, a predetermined number of samples of the tails of the plurality of Kernel signals are set to zero.

6. The method according to claim 1, wherein if the current OFDM signal is received And the adjusted previous OFDM signal, the cyclic prefix of the adjusted current OFDM signal is continuous with the tail of the adjusted previous OFDM signal, specifically:

The first few samples in the cyclic prefix of the adjusted current OFDM signal are equal to the plurality of samples of the tail of the adjusted previous OFDM signal.

7. The method according to claim 1, wherein if the current OFDM signal and the adjusted previous OFDM signal are received, the generating a noise signal according to the received signal is:

And extracting a difference signal of the plurality of samples in the current OFDM signal and the adjusted previous OFDM signal to generate the noise signal.

The method according to claim 7, wherein the method further comprises: transforming, by the current OFDM signal, a difference signal of the plurality of samples in the adjusted previous OFDM signal to a frequency domain;

And performing weight adjustment on the difference signal of the thousands of samples according to different weights of the respective subcarriers corresponding to the current OFDM signal, and converting back to the time domain;

Adjusting the amplitude of the difference signal of the plurality of samples and generating the noise signal.

9. A method according to any one of claims 1 to 8, characterized in that

If the current OFDM signal and the previous OFDM signal are received, the method further comprises: buffering the current OFDM signal to provide modulation for the next OFDM signal; if receiving the current OFDM signal and the adjusted upper An OFDM signal, the method further comprising: buffering the adjusted current OFDM signal to provide modulation for a next OFDM signal.

10. A method for modulating an OFDM signal, comprising:

Obtaining a current OFDM signal to which a cyclic prefix is added, a previous OFDM signal to which a cyclic prefix is added, and a previous OFDM signal superimposed with the first noise signal;

Generating a second noise signal of the previous OFDM signal according to the current OFDM signal to which the cyclic prefix is added and the previous OFDM signal superimposed with the first noise signal; superimposing the second noise signal on the superposition The first OFDM signal of the first noise signal is generated on the adjusted upper One OFDM;

Generating a first noise signal of a current OFDM signal according to the current OFDM signal to which a cyclic prefix is added and the previous OFDM signal to which a cyclic prefix is added, and superimposing the first noise signal on the current OFDM signal And generating a current OFDM signal superimposed with the first noise signal, wherein a cyclic prefix of the current OFDM signal superimposed with the first noise is continuous with a tail of the adjusted previous OFDM signal.

11. The method of claim 10, wherein

And generating, by the second noise signal of the last OFDM signal, the following: acquiring a plurality of second Kernel signals of different cyclic shifts corresponding to the adjusted previous OFDM signal, according to the current And acquiring an amplitude phase adjustment coefficient corresponding to each of the plurality of second Kernel signals by using an OFDM signal and a previous OFDM signal on which the first noise signal is superimposed, and generating the first according to the second Kernel signal and the corresponding amplitude phase adjustment coefficient Two noise signals;

The generating the first noise signal of the current OFDM signal, specifically: acquiring a plurality of first Kernel signals corresponding to different cyclic shifts corresponding to the number of the second Kernel signals corresponding to the current OFDM signal, according to adding a cyclic prefix Obtaining an amplitude phase adjustment coefficient corresponding to each of the plurality of first Kernel signals according to the current OFDM signal and the previous OFDM signal to which the cyclic prefix is added, and adjusting coefficients according to the first Kernel signal and the corresponding amplitude phase Generating the first noise signal.

The method according to claim 11, wherein the plurality of first Kernel signals or adjacent Kernel signals in the thousands of second Kernel signals are shifted by one shift;

The first noise signal of the current OFDM signal is a sum of products of the plurality of first Kernel signals and corresponding amplitude phase adjustment coefficients;

The second noise signal of the previous OFDM signal is the sum of the products of the plurality of second Kernel signals and the corresponding amplitude phase adjustment coefficients.

The method according to claim 12, wherein the first Kernel signal is a one-dimensional vector generated according to weights of respective subcarriers corresponding to a current OFDM signal; and the second Kernel signal is based on a previous OFDM signal. A one-dimensional vector generated by the weight of each corresponding subcarrier.

The method according to any one of claims 10 to 13, wherein the method further comprises:

The current OFDM signal superimposed with the first noise and the current OFDM signal to which the cyclic prefix is added are buffered to be supplied to the next OFDM signal.

15. A modulation apparatus for an OFDM signal, comprising:

a receiving unit, configured to receive a current OFDM signal and a previous OFDM signal or an adjusted previous OFDM signal;

a signal generating unit, configured to superimpose the noise signal on the current OFDM signal, to generate an adjusted current OFDM signal, and the cyclic prefix of the adjusted current OFDM signal and a tail or adjustment of the previous OFDM signal The tail of the last OFDM signal is continuous.

The OFDM signal modulating apparatus according to claim 15, wherein the noise generating unit comprises:

An acquiring module, configured to acquire, if the cyclic signals of different cyclic shifts corresponding to the current OFDM signal, thousands of pulsed Kernel signals;

a coefficient generating module, configured to obtain, according to the current OFDM signal, a previous phase OFDM signal corresponding to the previous OFDM signal or the adjusted previous OFDM signal;

And a noise generating module, configured to generate the noise signal according to the Kernel signal and a corresponding amplitude phase adjustment coefficient.

The OFDM signal modulating apparatus according to claim 15, further comprising:

And an adding unit, configured to add a cyclic prefix of the current OFDM signal before or after the noise signal is superimposed.

The modulating apparatus for an OFDM signal according to claim 15 or 16 or 17, wherein the method further comprises:

a delay unit, configured to buffer a current OFDM signal generated by the signal generating unit or The pre OFDM signal is provided to the next OFDM signal.

19. A modulation apparatus for an OFDM signal, comprising:

And an obtaining unit, configured to acquire a current OFDM signal with a cyclic prefix added, a previous OFDM signal with a cyclic prefix added, and a previous OFDM signal with the first noise signal superimposed thereon;

a noise generating unit, configured to generate a second noise signal of a previous OFDM signal according to the current OFDM signal added with a cyclic prefix and the previous OFDM signal superimposed with the first noise signal; and the second noise signal Superimposing on the previous OFDM signal superimposed with the first noise signal to generate an adjusted previous OFDM;

a signal generating unit, configured to generate a first noise signal of a current OFDM signal according to the current OFDM signal to which a cyclic prefix is added and the previous OFDM signal to which a cyclic prefix is added, and superimpose the first noise signal on A current OFDM signal on which the first noise signal is superimposed is generated on the current OFDM signal, and a cyclic prefix of the current OFDM signal superimposed with the first noise is continuous with a tail of the adjusted previous OFDM signal.

The apparatus according to claim 19, wherein the noise generating unit comprises: an acquiring module, configured to acquire, if the second cyclic signal corresponding to the adjusted previous OFDM signal, a thousand second a Kernel signal and a plurality of first kernel signals corresponding to the current OFDM signal and equal in number to the second Kernel signal;

a coefficient generating module, configured to generate, according to the current OFDM signal to which the cyclic prefix is added and the previous OFDM signal to which the first noise signal is added, an amplitude phase adjustment coefficient corresponding to each of the plurality of second Kernel signals, The current OFDM signal of the cyclic prefix and the previous OFDM signal to which the cyclic prefix is added, and the amplitude phase adjustment coefficients respectively corresponding to the plurality of first Kernel signals are generated;

a noise generating module, configured to generate a second noise signal of the previous OFDM signal according to the second Kernel signal and a corresponding amplitude phase adjustment coefficient, and generate the according to the first Kernel signal and a corresponding amplitude phase adjustment coefficient The first noise signal of the current OFDM signal.