CN112242968A - OFDM signal transmission method, device and equipment with high spectrum efficiency - Google Patents
OFDM signal transmission method, device and equipment with high spectrum efficiency Download PDFInfo
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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
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0006—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission format
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0056—Systems characterized by the type of code used
- H04L1/0071—Use of interleaving
Abstract
The embodiment of the invention provides a method, a device and equipment for transmitting an OFDM signal with high spectral efficiency, wherein the method comprises the following steps: acquiring an OFDM signal; 1/4 truncation is carried out on the OFDM signal to obtain a 1/4 truncation signal; connecting 1/4 cutoff signals with a preset number to obtain cascade signals; and carrying out signal transmission based on the cascade signal. Therefore, in the scheme, 1/4 truncation is performed on the OFDM signals, and a preset number of 1/4 truncation signals are cascaded, so that the preset number of OFDM signals can be transmitted each time, the transmission efficiency is improved, and the OFDM signal transmission with high spectrum efficiency is realized.
Description
Technical Field
The present invention relates to the field of digital signal processing methods, and in particular, to a method, an apparatus, and a device for transmitting OFDM signals with high spectral efficiency.
Background
The OFDM (Orthogonal Frequency Division Multiplexing) technology is one of multi-carrier modulation, and realizes parallel transmission of high-speed serial data through Frequency Division Multiplexing, and has a good capability of resisting multipath fading.
In the process of using the OFDM technology for data transmission and reception, OFDM signals need to be loaded on carriers for transmission, and since the carrier capacity is limited, only one OFDM signal can be loaded on each carrier, which results in low transmission efficiency.
Disclosure of Invention
Embodiments of the present invention provide a method, an apparatus, and a device for transmitting an OFDM signal with high spectral efficiency, so as to improve transmission efficiency. The specific technical scheme is as follows:
to achieve the above object, an embodiment of the present invention provides an OFDM signal transmission method, including:
acquiring an OFDM signal;
1/4 truncation is carried out on the OFDM signal to obtain a 1/4 truncation signal;
connecting 1/4 cutoff signals with a preset number to obtain cascade signals;
and carrying out signal transmission based on the cascade signal.
Optionally, the acquiring the OFDM signal includes:
acquiring a modulation signal of odd-even interweaving of subcarriers;
carrying out Hermite transformation on the modulation signals of the sub-carrier odd-even interweaving to obtain Hermite transformation signals;
and carrying out fast Fourier inverse transformation on the Hermite transformed signal to obtain an OFDM signal.
Optionally, the obtaining the modulated signal of the parity interleaving of the subcarriers includes:
acquiring a filling signal;
determining an odd frequency position and an even frequency position of each subcarrier;
and modulating the filling signal at the odd frequency position, and nulling the even frequency position to obtain a modulated signal of odd-even interleaving of subcarriers.
Optionally, the acquiring the fill signal includes:
acquiring a series of information sequences;
determining a high frequency position of the series of information sequences;
and placing the known useless signals into the high-frequency positions to obtain filling signals.
In order to achieve the above object, an embodiment of the present invention further provides an OFDM signal transmission apparatus, including:
an obtaining module, configured to obtain an OFDM signal;
a truncation module, configured to perform 1/4 truncation on the OFDM signal to obtain a 1/4 truncated signal;
the connecting module is used for connecting 1/4 cutoff signals with preset quantity to obtain cascade signals;
and the output module is used for carrying out signal transmission based on the cascade signal.
Optionally, the obtaining module includes:
the acquisition submodule is used for acquiring a modulation signal of the odd-even interweaving of the subcarriers;
the first transformation submodule is used for carrying out Hermite transformation on the modulation signals of the sub-carrier odd-even interweaving to obtain Hermite transformation signals;
and the second transformation submodule is used for carrying out inverse fast Fourier transform on the Hermite transformation signal to obtain an OFDM signal.
Optionally, the obtaining sub-module includes:
an acquisition unit configured to acquire a fill signal;
a determining unit for determining an odd frequency position and an even frequency position of each subcarrier;
and the modulation unit is used for modulating the filling signal at the odd frequency position and nulling the even frequency position to obtain a modulation signal of odd-even interleaving of subcarriers.
Optionally, the obtaining unit is specifically configured to:
acquiring a series of information sequences;
determining a high frequency position of the series of information sequences;
and placing the known useless signals into the high-frequency positions to obtain filling signals.
In order to achieve the above object, an embodiment of the present invention further provides an electronic device, including a processor and a memory;
a memory for storing a computer program;
and the processor is used for realizing any OFDM signal transmission method when executing the program stored in the memory.
By applying the embodiment of the invention, 1/4 truncation is carried out on the OFDM signals, a preset number of 1/4 truncation signals are cascaded, the obtained cascade signals are equivalent to contain the information carried by the preset number of OFDM signals, and the transmission of the cascade signals is equivalent to the transmission of the preset number of OFDM signals every time, so that the transmission efficiency is improved, and the transmission of the OFDM signals with high spectrum efficiency is realized.
Of course, not all of the advantages described above need to be achieved at the same time in the practice of any one product or method of the invention.
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 description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a first flowchart of an OFDM signal transmission method according to an embodiment of the present invention;
fig. 2 is a second flowchart of an OFDM signal transmission method according to an embodiment of the present invention;
fig. 3 is a schematic diagram of parity sub-carriers of an OFDM signal according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a periodicity of a time domain of an OFDM signal after an inverse fast fourier transform according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an OFDM signal transmission apparatus according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to achieve the above object, embodiments of the present invention provide an OFDM signal transmission method, an apparatus, and a device, which may be applied to an electronic device, and are not limited specifically. The OFDM signal transmission method will be described in detail first.
Fig. 1 is a first flowchart of an OFDM signal transmission method according to an embodiment of the present invention, including:
s101: an OFDM signal is acquired.
In one embodiment, S101 may include: the method comprises the steps of obtaining modulation signals of sub-carrier odd-even interweaving, carrying out Hermite transformation on the modulation signals of the sub-carrier odd-even interweaving to obtain Hermite transformation signals, and carrying out fast Fourier inverse transformation on the Hermite transformation signals to obtain OFDM signals.
In one embodiment, S101 may include: the method comprises the steps of obtaining filling signals, determining the odd frequency position and the even frequency position of each subcarrier, modulating the filling signals at the odd frequency position, and nulling the even frequency position to obtain modulated signals of odd-even interleaving of the subcarriers.
A carrier is an electromagnetic wave modulated in frequency, amplitude or phase to transmit speech, audio, image or other signals, and a subcarrier is a subchannel in multicarrier communications, and odd-frequency subcarriers and even-frequency subcarriers are distinguished by ordering the subcarriers. For example, the first subcarrier is an odd frequency subcarrier and the second subcarrier is an even frequency subcarrier.
The modulation principle of subcarrier parity interleaving is described below:
for example, if the frequency interval between two adjacent subcarriers is set to be Ω, then when the subcarrier interval is k Ω, then the cross-talk interference between the two subcarriers will fall at the frequency of k Ω.
In one case, data is modulated at odd-frequency sub-carrier positions, and since the frequency interval between every two odd-frequency sub-carriers is even times, the cross-beat interference occurring between every two odd-frequency sub-carriers falls in even-frequency sub-carriers of the signal and does not fall in odd-frequency sub-carriers of the signal, so that the signal modulated at the odd-frequency sub-carrier positions is not interfered.
For example, data is modulated on odd frequency subcarriers with frequencies of Ω and 3 Ω, and the frequency interval between the two odd frequency subcarriers is 2 Ω, so that the inter-beat interference between the two odd frequency subcarriers falls on even frequency subcarriers with frequencies of 2 Ω, and no modulation signal is present on even frequency subcarriers with frequencies of 2 Ω, and thus no interference is generated on the data.
In another case, data is modulated at even frequency subcarrier positions, and since the frequency interval between every two even frequency subcarriers is even times, the cross-beat interference occurring between every two even frequency subcarriers falls into the even frequency subcarriers of the signal, which causes interference to the signal modulated at the even frequency subcarrier positions.
For example, data is modulated on odd frequency subcarriers with frequencies of 2 Ω and 4 Ω, and at this time, the frequency interval between the two odd frequency subcarriers is 2 Ω, then the inter-beat interference between the two odd frequency subcarriers falls at even frequency subcarriers with frequencies of 2 Ω, and at this time, modulated signals exist on even frequency subcarriers with frequencies of 2 Ω, so that the subcarrier inter-beat phenomenon generates interference on data.
In one embodiment, S101 may include: the method may include acquiring a series of information sequences, and embedding a known unwanted signal into a high-frequency position of the series of information sequences, where the known unwanted signal may be a periodic signal or a random signal, and the like, and is not limited specifically.
For example, a series of information sequences may be generated by a signal generator, which may be an LC oscillator signal generator, a voltage controlled oscillator signal generator, a frequency synthesized signal generator, and the like, without limitation.
Because signals are affected by the chromatic dispersion and the chromatic dispersion of an optical fiber polarization film in the process of optical fiber transmission, and devices passing through the optical fiber polarization film due to analog-to-digital conversion and digital-to-analog conversion in the transmission process have the characteristics of nonlinearity and limited bandwidth, the frequency selective attenuation phenomenon occurs when the signals are received. The device which passes through due to analog-to-digital and digital-to-analog conversion in the transmission process comprises the following components: a filter, an amplifier, a capacitor, an inductor, etc., and is not particularly limited. The frequency selective attenuation phenomenon mostly occurs at the high-frequency position of the signal, and by applying the embodiment, a plurality of known useless input signals are placed at the high-frequency position, so that most of selective frequency attenuation after transmission falls at the known useless signals, and the influence of the attenuation on the signal is reduced.
S102: the OFDM signal is 1/4 truncated to obtain 1/4 truncated signal.
In one case, S102 may include: assuming that the laser produces a stable frequency of ω0The monochromatic continuous light wave of (a) is represented by C (t) ═ cA0 cos(ω0t)，A0Amplitude of the laser carrier, ω0T represents time as the angular frequency of the optical carrier. Assume that the OFDM signal acquired in S101 is represented as:
wherein N represents the total number of subcarriers, k represents the number of the sequence numbers of the subcarriers, ckTo represent the OFDM symbol loaded on the k-th subcarrier, j is an imaginary unit, fkRepresents the subcarrier frequency corresponding to the k-th subcarrier, T represents the time of OFDM symbol transmission, and T represents the time period. The time domain front 1/4 signal of the OFDM signal may be expressed as:
at this time, [ T/4, T/2 ] in the OFDM signal]Within the time domain interval (t)2＝t1The + T/4) signal may be expressed as:
since the OFDM signal is modulated on odd frequency subcarriers during the odd-even subcarrier modulation, i.e. k takes an odd number, there are:
x1indicating that the OFDM signal is modulated only on the subcarriers at 4n + 1. Referring to fig. 3, fig. 3 shows a schematic diagram of OFDM signal modulation on odd frequency subcarriers, where arrows represent subcarriers of the modulated OFDM signal and dots represent subcarriers of the unmodulated OFDM signal. As shown in the upper left-hand portion of fig. 3, for T/4, T/2]The signals in the time domain interval are:
it can be concluded at this point that the signal modulated on the subcarrier at 4n +1 can be derived from the time domain first 1/4 signal on the subcarrier at 4n + 1.
x2Indicating that the wanted signal is modulated on a sub-carrier at 4n +3, as shown in the lower left part of fig. 3, when for T/4, T/2]The signals in the time domain interval are:
it can be concluded at this point that the signal modulated on the subcarrier at 4n +3 can be derived from the time domain first 1/4 signal on the subcarrier at 4n + 3.
Since the signal is modulated on odd frequency subcarriers, as shown on the right side in fig. 3, the IFFT-based periodicity at this time can be found as:
x(t)＝IFFT[X(f)]＝IFFT[X1(f)+X2(f)]
＝IFFT[X1(f)]+IFFT[X2(f)]
＝x1(t)+x2(t)
wherein, x (f) represents the OFDM signal converted to the frequency domain, that is, x (t) is obtained after being converted to the frequency domain; x1(f) Representing the time domain front 1/4OFDM signal converted to the frequency domain, i.e. x1(t) converting to the frequency domain to obtain X1(f)；X2(f) T/4, T/2 representing conversion to frequency domain]OFDM signals in the time domain, i.e. x2(t) converting to the frequency domain to obtain X2(f)。
Since the signals are subjected to the Hermite transform operation before IFFT, x (t) is a real number signal, let x1(t)＝a1+b1·j，x2(t)＝a2+b2J, wherein a1，a2，b1，b2For any real number, then:
x(t1)＝x1(t1)+x2(t1)
＝a1+b1·j+a2+b2·j
＝a1+a2+(b1+b2)·j
x(t2)＝x1(t2)+x2(t2)
＝x1(t1)·j+x2(t1)·(-j)
＝a1·j-b1-a2·j+b2
＝(a1-a2)·j-(b1-b2)
since x (t) is a real number signal, x (t)1)x(t2) Is also a real signal, can be obtained as1＝a2，b1＝-b2To obtain x1(t)＝a1+b1i，x2(t)＝a1-b1i, i is an imaginary unit. Referring to fig. 4, fig. 4 is a schematic diagram illustrating a time domain periodicity of an OFDM signal modulated on odd-frequency subcarriers after inverse fast fourier transform. An OFDM signal modulated on subcarriers at 4n +1 is shown as 401 in fig. 4, an OFDM signal modulated on subcarriers at 4n +3 is shown as 402 in fig. 4, and an OFDM signal modulated on odd subcarriers is shown as 403 in fig. 4. Since x (t) is equal to x1(t)+x2(t) gives x (t) ═ 2a1At this time, it can be deduced that the OFDM signal can be obtained from an OFDM signal modulated on a subcarrier at 4n + 1; similarly, the OFDM signal may be derived from an OFDM signal modulated on subcarriers at 4n + 3.
Through the derivation process, the OFDM signal modulated on the subcarrier at 4n +1 can be recovered from the signal of 1/4 before the time domain, and the OFDM signal can be obtained from the OFDM signal modulated on the subcarrier at 4n +1, so that 1/4 truncation can be performed on the signal during transmission, and the time domain interval occupied by the signal can be saved.
S103: and connecting a preset number of 1/4 truncated signals to obtain a cascade signal.
In one embodiment, a predetermined number of 1/4 truncated signals are concatenated to obtain a cascade signal.
In the present embodiment, a predetermined number of 1/4 cutoff signals are connected to obtain a cascade signal. The preset number may be 2, 3, 4, etc., and is not limited specifically. In one case, every 4 1/4 truncated signals may be concatenated to obtain a cascade signal. For example, if the preset number is 16, every 4 1/4 truncated signals are concatenated, so as to obtain 4 cascade signals. By applying the embodiment, the time domain interval which originally can only transmit one OFDM signal can transmit four OFDM signals, thereby improving the transmission efficiency of the signals.
S104: and carrying out signal transmission based on the cascade signal.
In one embodiment, the concatenated signal may be transmitted, and the concatenated signal may improve transmission efficiency, and may reduce subcarrier cross-talk interference and frequency selective attenuation due to the fact that the OFDM signal is subjected to the filling of unwanted signals and the modulation of odd and even subcarriers.
By applying the embodiment shown in fig. 1 of the present invention, in the first aspect, 1/4 truncation is performed on OFDM signals, and a preset number of 1/4 truncation signals are cascaded, so that the preset number of OFDM signals can be transmitted in one signal transmission, thereby improving the transmission efficiency of signals and realizing OFDM signal transmission with high spectral efficiency.
In a second aspect, in an embodiment, because the OFDM signal transmitted in a unit time is not reduced, under the condition that the spectrum efficiency is not damaged, the influence of subcarrier cross-beat interference and frequency selective attenuation on the signal is reduced, so that the error rate in the data transmission process is reduced. Meanwhile, under the condition of the same signal-to-noise ratio, the error rate in the data transmission process is reduced, so that the receiving sensitivity performance is improved.
Fig. 2 is a second flowchart of an OFDM signal transmission method according to an embodiment of the present invention, including:
s201: a series of information sequences is obtained.
For example, a series of information sequences may be generated by a signal generator, which may be an LC oscillator signal generator, a voltage controlled oscillator signal generator, a frequency synthesized signal generator, and the like, without limitation.
S202: a filling signal is obtained by placing a known useless signal at a high-frequency position of a series of information sequences.
In one embodiment, the high frequency position of the string of information sequences may be determined; and placing the known useless signals into the high-frequency positions to obtain filling signals.
In this embodiment, after obtaining a series of information sequences, a known unwanted signal may be put into a high-frequency position of the series of information sequences, and the known unwanted signal may be a periodic signal, a random signal, or the like, and is not limited specifically.
Because signals are affected by the chromatic dispersion and the chromatic dispersion of an optical fiber polarization film in the process of optical fiber transmission, and devices passing through the optical fiber polarization film due to analog-to-digital conversion and digital-to-analog conversion in the transmission process have the characteristics of nonlinearity and limited bandwidth, the frequency selective attenuation phenomenon occurs when the signals are received. The device which passes through due to analog-to-digital and digital-to-analog conversion in the transmission process comprises the following components: a filter, an amplifier, a capacitor, an inductor, etc., and is not particularly limited. The frequency selective attenuation phenomenon mostly occurs at the high-frequency position of the signal, and by applying the embodiment, a plurality of known useless input signals are placed at the high-frequency position, so that most of selective frequency attenuation after transmission falls at the known useless signals, and the influence of the attenuation on the signal is reduced.
S203: and carrying out subcarrier parity interleaving modulation on the filling signal to obtain a subcarrier parity interleaved modulation signal.
In one embodiment, the odd and even frequency positions of each subcarrier are determined, the padding signal is modulated at the odd frequency positions, and the even frequency positions are nulled to obtain modulated signals of odd-even interleaving of subcarriers.
A carrier is an electromagnetic wave modulated in frequency, amplitude or phase to transmit speech, audio, image or other signals, and a subcarrier is a subchannel in multicarrier communications, and odd-frequency subcarriers and even-frequency subcarriers are distinguished by ordering the subcarriers. For example, the first subcarrier is an odd frequency subcarrier and the second subcarrier is an even frequency subcarrier.
The modulation principle of subcarrier parity interleaving is described below:
for example, if the frequency interval between two adjacent subcarriers is set to be Ω, then when the subcarrier interval is k Ω, then the cross-talk interference between the two subcarriers will fall at the frequency of k Ω.
In one case, data is modulated at odd-frequency sub-carrier positions, and since the frequency interval between every two odd-frequency sub-carriers is even times, the cross-beat interference occurring between every two odd-frequency sub-carriers falls in even-frequency sub-carriers of the signal and does not fall in odd-frequency sub-carriers of the signal, so that the signal modulated at the odd-frequency sub-carrier positions is not interfered.
For example, data is modulated on odd frequency subcarriers with frequencies of Ω and 3 Ω, and the frequency interval between the two odd frequency subcarriers is 2 Ω, so that the inter-beat interference between the two odd frequency subcarriers falls on even frequency subcarriers with frequencies of 2 Ω, and no modulation signal is present on even frequency subcarriers with frequencies of 2 Ω, and thus no interference is generated on the data.
In another case, data is modulated at even frequency subcarrier positions, and since the frequency interval between every two even frequency subcarriers is even times, the cross-beat interference occurring between every two even frequency subcarriers falls into the even frequency subcarriers of the signal, which causes interference to the signal modulated at the even frequency subcarrier positions.
For example, data is modulated on odd frequency subcarriers with frequencies of 2 Ω and 4 Ω, and at this time, the frequency interval between the two odd frequency subcarriers is 2 Ω, then the inter-beat interference between the two odd frequency subcarriers falls at even frequency subcarriers with frequencies of 2 Ω, and at this time, modulated signals exist on even frequency subcarriers with frequencies of 2 Ω, so that the subcarrier inter-beat phenomenon generates interference on data.
S204: and carrying out frequency domain to time domain conversion on the modulated signal of the sub-carrier odd-even interweaving to obtain the OFDM signal.
In one embodiment, S204 may include: carrying out Hermitian (Hermitian) transformation on the modulation signals of the sub-carrier odd-even interweaving to obtain Hermitian transformation signals; the hermitian Transform signal is subjected to Inverse Fast Fourier Transform (IFFT) to obtain an OFDM signal.
S205: the OFDM signal is 1/4 truncated to obtain 1/4 truncated signal.
In one case, the laser is assumed to produce a stable frequency of ω0The monochromatic continuous light wave of (a) is represented by c (t) ═ a0cos(ω0t)，A0Amplitude of the laser carrier, ω0Is the angular frequency of the optical carrier and t is time. It is assumed that the OFDM signal acquired in S204 is represented as:
wherein N represents the total number of subcarriers, k represents the number of the sequence numbers of the subcarriers, ckTo represent the OFDM symbol loaded on the k-th subcarrier, j is an imaginary unit, fkRepresents the subcarrier frequency corresponding to the k-th subcarrier, T represents the OFDM symbol transmission time, and T represents the time period. The time domain front 1/4 signal of the OFDM signal may be expressed as:
at this time, [ T/4, T/2 ] in the OFDM signal]Within the time domain interval (t)2＝t1The + T/4) signal may be expressed as:
since the OFDM signal is modulated on odd frequency subcarriers during the odd-even subcarrier modulation, i.e. k takes an odd number, there are:
x1indicating that the OFDM signal is modulated only on the subcarriers at 4n + 1. Referring to fig. 3, fig. 3 shows a schematic diagram of OFDM signal modulation on odd frequency subcarriers, where arrows represent subcarriers of the modulated OFDM signal and dots represent subcarriers of the unmodulated OFDM signal. As shown in the upper left-hand portion of fig. 3, for T/4, T/2]The signals in the time domain interval are:
it can be concluded at this point that the signal modulated on the subcarrier at 4n +1 can be derived from the time domain first 1/4 signal on the subcarrier at 4n + 1.
x2Indicating that the wanted signal is modulated on a sub-carrier at 4n +3, as shown in the lower left part of fig. 3, when for T/4, T/2]The signals in the time domain interval are:
it can be concluded at this point that the signal modulated on the subcarrier at 4n +3 can be derived from the time domain first 1/4 signal on the subcarrier at 4n + 3.
Since the signal is modulated on odd frequency subcarriers, as shown on the right side in fig. 3, the IFFT-based periodicity at this time can be found as:
x(t)＝IFFT[X(f)]＝IFFT[X1(f)+X2(f)]
＝IFFT[X1(f)]+IFFT[X2(f)]
＝x1(t)+x2(t)
wherein, x (f) represents the OFDM signal converted to the frequency domain, that is, x (t) is obtained after being converted to the frequency domain; x1(f) Representing the time domain front 1/4OFDM signal converted to the frequency domain, i.e. theX is to be1(t) converting to the frequency domain to obtain X1(f)；X2(f) T/4, T/2 representing conversion to frequency domain]OFDM signals in the time domain, i.e. x2(t) converting to the frequency domain to obtain X2(f)。
Since the signals are subjected to the Hermite transform operation before IFFT, x (t) is a real number signal, let x1(t)＝a1+b1·j，x2(t)＝a2+b2J, wherein a1，a2，b1，b2For any real number, then:
x(t1)＝x1(t1)+x2(t1)
＝a1+b1·j+a2+b2·j
＝a1+a2+(b1+b2)·j
x(t2)＝x1(t2)+x2(t2)
＝x1(t1)·j+x2(t1)·(-j)
＝a1·j-b1-a2·j+b2
＝(a1-a2)·j-(b1-b2)
since x (t) is a real number signal, x (t)1)x(t2) Is also a real signal, can be obtained as1＝a2，b1＝-b2To obtain x1(t)＝a1+b1i，x2(t)＝a1-b1i, i is an imaginary unit. Referring to fig. 4, fig. 4 is a schematic diagram illustrating a time domain periodicity of an OFDM signal modulated on odd-frequency subcarriers after inverse fast fourier transform. An OFDM signal modulated on subcarriers at 4n +1 is shown as 401 in fig. 4, an OFDM signal modulated on subcarriers at 4n +3 is shown as 402 in fig. 4, and an OFDM signal modulated on odd subcarriers is shown as 403 in fig. 4. Since x (t) is equal to x1(t)+x2(t) gives x (t) ═ 2a1At this time, it can be deduced that the OFDM signal can be modulated by a sub-signal at 4n +1Obtaining an OFDM signal on a carrier; similarly, the OFDM signal may be derived from an OFDM signal modulated on subcarriers at 4n + 3.
Through the derivation process, the OFDM signal modulated on the subcarrier at 4n +1 can be recovered from the signal of 1/4 before the time domain, and the OFDM signal can be obtained from the OFDM signal modulated on the subcarrier at 4n +1, so that 1/4 truncation can be performed on the signal during transmission, and the time domain interval occupied by the signal can be saved.
S206: and connecting a preset number of 1/4 truncated signals to obtain a cascade signal.
In one embodiment, after 1/4 truncated signals are obtained, a predetermined number of 1/4 truncated signals are concatenated to obtain a cascade signal.
In the present embodiment, a predetermined number of 1/4 cutoff signals are connected to obtain a cascade signal. The preset number may be 2, 3, 4, etc., and is not limited specifically. In one case, every 4 1/4 truncated signals may be concatenated to obtain a cascade signal. For example, if the preset number is 16, every 4 1/4 truncated signals are concatenated, so as to obtain 4 cascade signals. By applying the embodiment, the time domain interval which originally can only transmit one OFDM signal can transmit four OFDM signals, thereby improving the transmission efficiency of the signals.
S207: the cascade signal is transmitted.
In one embodiment, the concatenated signal may be transmitted, and the concatenated signal may improve transmission efficiency, and may reduce subcarrier cross-talk interference and frequency selective attenuation due to the fact that the OFDM signal is subjected to the filling of unwanted signals and the modulation of odd and even subcarriers.
By applying the embodiment shown in fig. 2 of the present invention, in the first aspect, 1/4 truncation is performed on OFDM signals, and a preset number of 1/4 truncation signals are cascaded, so that the preset number of OFDM signals can be transmitted in one signal transmission, thereby improving the transmission efficiency of signals and realizing OFDM signal transmission with high spectral efficiency.
In a second aspect, in an embodiment, because the OFDM signal transmitted in a unit time is not reduced, under the condition that the spectrum efficiency is not damaged, the influence of subcarrier cross-beat interference and frequency selective attenuation on the signal is reduced, so that the error rate in the data transmission process is reduced. Meanwhile, under the condition of the same signal-to-noise ratio, the error rate in the data transmission process is reduced, so that the receiving sensitivity performance is improved.
Corresponding to the above method embodiment, an embodiment of the present invention further provides an OFDM signal transmission apparatus, as shown in fig. 5, including:
an obtaining module 501, configured to obtain an OFDM signal;
a truncation module 502, configured to perform 1/4 truncation on the OFDM signal, so as to obtain 1/4 truncated signal;
a connection module 503, configured to connect a preset number of 1/4 truncated signals to obtain a cascade signal;
an output module 504, configured to perform signal transmission based on the cascade signal.
In one embodiment, the obtaining module 501 includes: an acquisition sub-module, a first transformation sub-module and a second transformation sub-module (not shown in the figure), wherein,
the acquisition submodule is used for acquiring a modulation signal of the odd-even interweaving of the subcarriers;
the first transformation submodule is used for carrying out Hermite transformation on the modulation signals of the sub-carrier odd-even interweaving to obtain Hermite transformation signals;
and the second transformation submodule is used for carrying out fast Fourier inverse transformation on the Hermite transformation signal to obtain a time domain signal.
In one embodiment, the acquisition submodule includes: an acquisition unit, a determination unit and a modulation unit (not shown in the figure), wherein,
an acquisition unit configured to acquire a fill signal;
a determining unit for determining an odd frequency position and an even frequency position of each subcarrier;
and the modulation unit is used for modulating the filling signal at the odd frequency position and nulling the even frequency position to obtain a modulation signal of odd-even interleaving of subcarriers.
In one embodiment, the obtaining unit is specifically configured to:
acquiring a series of information sequences;
determining a high frequency position of the series of information sequences;
and placing the known useless signals into the high-frequency positions to obtain filling signals.
By applying the embodiment shown in fig. 5 of the present invention, in the first aspect, 1/4 truncation is performed on OFDM signals, and a preset number of 1/4 truncation signals are cascaded, so that the preset number of OFDM signals can be transmitted in one signal transmission, thereby improving the transmission efficiency of signals and realizing OFDM signal transmission with high spectral efficiency.
In a second aspect, in an embodiment, because the OFDM signal transmitted in a unit time is not reduced, under the condition that the spectrum efficiency is not damaged, the influence of subcarrier cross-beat interference and frequency selective attenuation on the signal is reduced, so that the error rate in the data transmission process is reduced. Meanwhile, under the condition of the same signal-to-noise ratio, the error rate in the data transmission process is reduced, so that the receiving sensitivity performance is improved.
An embodiment of the present invention further provides an electronic device, as shown in fig. 6, including a processor 601 and a memory 602,
a memory 602 for storing a computer program;
the processor 601 is configured to implement any one of the OFDM signal transmission methods described above when executing the program stored in the memory 602.
The Memory mentioned in the above electronic device may include a Random Access Memory (RAM) or a Non-Volatile Memory (NVM), such as at least one disk Memory. Optionally, the memory may also be at least one memory device located remotely from the processor.
The Processor may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; but also Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components.
In yet another embodiment provided by the present invention, a computer-readable storage medium is further provided, in which a computer program is stored, and the computer program, when executed by a processor, implements the steps of any of the OFDM signal transmission methods described above.
In a further embodiment provided by the present invention, there is also provided a computer program product containing instructions which, when run on a computer, cause the computer to perform any of the OFDM signal transmission methods of the above embodiments.
In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, apparatus embodiments, device embodiments, computer-readable storage medium embodiments, and computer program product embodiments are described for simplicity as they are substantially similar to method embodiments, where relevant, reference may be made to some descriptions of method embodiments.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (9)
1. An OFDM signal transmission method, comprising:
acquiring an OFDM signal;
1/4 truncation is carried out on the OFDM signal to obtain a 1/4 truncation signal;
connecting 1/4 cutoff signals with a preset number to obtain cascade signals;
and carrying out signal transmission based on the cascade signal.
2. The method of claim 1, wherein the obtaining the OFDM signal comprises:
acquiring a modulation signal of odd-even interweaving of subcarriers;
carrying out Hermite transformation on the modulation signals of the sub-carrier odd-even interweaving to obtain Hermite transformation signals;
and carrying out fast Fourier inverse transformation on the Hermite transformed signal to obtain an OFDM signal.
3. The method of claim 2, wherein the obtaining the subcarrier parity interleaved modulated signal comprises:
acquiring a filling signal;
determining an odd frequency position and an even frequency position of each subcarrier;
and modulating the filling signal at the odd frequency position, and nulling the even frequency position to obtain a modulated signal of odd-even interleaving of subcarriers.
4. The method of claim 3, wherein the obtaining the fill signal comprises:
acquiring a series of information sequences;
determining a high frequency position of the series of information sequences;
and placing the known useless signals into the high-frequency positions to obtain filling signals.
5. An OFDM signal transmission apparatus, comprising:
an obtaining module, configured to obtain an OFDM signal;
a truncation module, configured to perform 1/4 truncation on the OFDM signal to obtain a 1/4 truncated signal;
the connecting module is used for connecting 1/4 cutoff signals with preset quantity to obtain cascade signals;
and the output module is used for carrying out signal transmission based on the cascade signal.
6. The apparatus of claim 5, wherein the obtaining module comprises:
the acquisition submodule is used for acquiring a modulation signal of the odd-even interweaving of the subcarriers;
the first transformation submodule is used for carrying out Hermite transformation on the modulation signals of the sub-carrier odd-even interweaving to obtain Hermite transformation signals;
and the second transformation submodule is used for carrying out inverse fast Fourier transform on the Hermite transformation signal to obtain an OFDM signal.
7. The apparatus of claim 6, wherein the acquisition submodule comprises:
an acquisition unit configured to acquire a fill signal;
a determining unit for determining an odd frequency position and an even frequency position of each subcarrier;
and the modulation unit is used for modulating the filling signal at the odd frequency position and nulling the even frequency position to obtain a modulation signal of odd-even interleaving of subcarriers.
8. The apparatus according to claim 7, wherein the obtaining unit is specifically configured to:
acquiring a series of information sequences;
determining a high frequency position of the series of information sequences;
and placing the known useless signals into the high-frequency positions to obtain filling signals.
9. An electronic device comprising a processor and a memory;
a memory for storing a computer program;
a processor for implementing the method steps of any of claims 1 to 4 when executing a program stored in the memory.
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