CN113660187A - Orthogonal multi-carrier sending method, receiving method and device based on random phase rotation - Google Patents
Orthogonal multi-carrier sending method, receiving method and device based on random phase rotation 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
- H04L27/2626—Arrangements specific to the transmitter only
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2697—Multicarrier modulation systems in combination with other modulation techniques
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L63/00—Network architectures or network communication protocols for network security
- H04L63/16—Implementing security features at a particular protocol layer
Abstract
The invention discloses a method and a device for sending and receiving orthogonal multi-carrier based on random phase rotation, wherein the sending method comprises the following steps: obtaining an OFDM signal to be transmitted, and performing phase rotation on each subcarrier in each frame of data of the OFDM signal to be transmitted by using a plurality of pre-generated phase rotation values to obtain the OFDM signal after phase rotation, wherein the phase rotation values are randomly generated by using a secret key, and each subcarrier respectively and correspondingly uses different phase rotation values; and transforming the OFDM signal after phase rotation into a signal with a required format and then transmitting the signal. The invention can prevent the OFDM signal from being demodulated by a non-target receiving end during transmission, and has the advantages of simple realization method, low complexity, high transmission safety and reliability and the like.
Description
Technical Field
The present invention relates to the field of OFDM (Orthogonal Frequency Division Multiplexing) communication transmission technologies, and in particular, to a method and a device for transmitting and receiving Orthogonal multiple carriers based on random phase rotation.
Background
The OFDM technology is an important technology in fourth generation mobile communication systems and plays a dominant role in the 5G mobile communication standard. OFDM improves spectrum utilization efficiency by exploiting orthogonality between subcarriers, reduces inter-symbol interference caused by multipath by a cyclic prefix, and implements modulation and demodulation of an OFDM signal using fast fourier transform.
In the data channel of the current OFDM communication, each subcarrier adopts a uniform Modulation mode, generally MPSK (Multiple phase shift keying), MQAM (Multiple Quadrature Amplitude Modulation), and the like, and the Modulation mode changes little within one transmission pulse time, and since the constellation diagram of each symbol in the OFDM can be selected from an estimation scheme, a non-signal receiving end (such as a communication reconnaissance party) can identify the Modulation mode by using a high-order moment method, and further can perform symbol timing estimation and demodulation decision on the carrying data of each data channel. That is, during the conventional OFDM signal transmission, all the subcarriers are easy to detect, and the modulation scheme of each subcarrier is predictable, so that the demodulation decision is easy to be made, which affects the security of OFDM signal transmission.
In order to improve the safety performance of OFDM signal transmission, the prior art mainly adopts the following methods:
1. a rotational precoding method is adopted to reduce the peak-to-average power ratio (PAPR) of the OFDM signal. In this type of method, rotation appears as jumping from one constellation point to another constellation point on a QAM constellation diagram, but because the phase rotation value is selected limitedly, the rotated baseband data still belongs to the same constellation point, and therefore, the demodulation decision by the non-signal receiving end still cannot be effectively prevented.
2. And reducing the peak-to-average power ratio (PAPR) of the transmitted OFDM signal by adopting the phase rotation factor, namely selecting the phase rotation factor from the set { -1,1}, and then uniformly performing the same phase rotation on each frequency domain subsequence. However, in this type of method, since only the subsequences are uniformly phase-rotated in the same way, the rotated OFDM signal is still easy to demodulate.
3. The method adopts a pilot frequency phase rotation mode, namely, after a receiver extracts pilot frequency data of an OFDM symbol, phase rotation on the pilot frequency is calculated, so that a phase rotation factor on the OFDM symbol is calculated, and corresponding compensation is carried out on a data signal. However, in this type of method, the phase rotation factor is derived from the sampling clock offset at the receiving end, so the phase rotation of each subcarrier data is consistent, and the signal is still easy to demodulate after the phase rotation.
4. The transmitting terminal equally divides the OFDM data subcarrier into two halves, wherein one half of the subcarrier transmits original information, and the other half of the subcarrier transmits a copy of the original information which is subjected to phase rotation, wherein the phase rotation adopts a regular rotation mode. In the method, original information and a phase-rotated original information copy need to be transmitted simultaneously, the complex realization and the large data volume needed to be transmitted are realized, and signals are still easy to demodulate only by adopting regular phase rotation on part of the molecular carriers.
5. At an OFDM transmitting end, selecting information data at a fixed subcarrier position in a frequency domain to obtain complex conjugate, and filling the obtained conjugate encoded data into subcarriers at other fixed positions; the receiver extracts information data and conjugate coding data of the corresponding subcarrier position of each symbol in a frequency domain, and estimates symbol phase rotation caused by residual carrier frequency offset based on a conjugate relation, so that not only is the implementation complex, but also the signal is easy to demodulate.
In summary, when the OFDM signal is transmitted in the prior art, various methods are easy to avoid being detected by communication and cannot effectively prevent being demodulated and determined by the non-signal receiving end, so the safety performance of OFDM signal transmission is not high.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the technical problems in the prior art, the invention provides an orthogonal multi-carrier transmitting method, a receiving method and a device based on random phase rotation, which can prevent demodulation by a non-target receiving end, have the advantages of simple realization method, low complexity and high transmission safety and reliability.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a random phase rotation-based orthogonal multi-carrier transmission method, the transmission method comprising:
obtaining an OFDM signal to be transmitted, and performing phase rotation on each subcarrier in each frame of data of the OFDM signal to be transmitted by using a plurality of pre-generated phase rotation values to obtain the OFDM signal after phase rotation, wherein the phase rotation values are randomly generated by using a secret key, and each subcarrier respectively and correspondingly uses different phase rotation values;
and converting the OFDM signal after the phase rotation into a signal with a required format and then sending the signal.
Further, the pre-generated pseudo random sequence is divided into G.N data { z ] according to Q bitskK is 0, …, G · N-1, yielding G · N phase rotation values:
wherein, G is the number of OFDM symbols in the OFDM signal, and N is the number of subcarriers in each OFDM symbol.
Further, the method further includes using a part of subcarriers in the OFDM signal to be transmitted as a key channel for transmitting the key, and performing phase rotation on a pilot channel and/or the key channel before transmitting the OFDM signal to be transmitted.
Further, the key channels are configured to be arranged according to a preset rule to form a regular arrangement, or configured to be arranged in a random arrangement mode according to an arrangement position generated by a key at random.
Further, when performing phase rotation on each subcarrier in each frame of data of the OFDM signal to be transmitted, specifically, each frame of data performs phase rotation on each subcarrier using a phase rotation table generated by a different key, where the phase rotation table includes a plurality of phase rotation values, and the key of the next frame of data is transmitted simultaneously when transmitting the current frame of data.
Furthermore, a plurality of phase rotation tables are generated by using a plurality of different keys in advance, and an optimal phase rotation table is selected from the plurality of phase rotation tables according to the effect of phase rotation of each frame of data, so that the phase rotation of each subcarrier in the current frame is performed by using a plurality of phase rotation values in the optimal phase rotation table.
Further, when the OFDM signal after phase rotation is converted into a signal of a desired format and transmitted, the method further includes performing error correction coding on each key, converting the key data into key data, and transmitting the key data.
A receiving method for the above transmitting method, comprising the steps of:
receiving OFDM signals sent by a sending end, and transforming the OFDM signals into OFDM data after preprocessing;
acquiring a key from the OFDM data and recovering the phase rotation table by using the acquired key;
respectively carrying out phase derotation on each subcarrier data in the OFDM data by using the recovered phase rotation table to obtain derotated data;
and demodulating the data after the de-rotation.
A random phase rotation-based orthogonal multicarrier transmission apparatus comprising:
a phase rotation value module for randomly generating a plurality of phase rotation values using the secret key;
the phase rotation module is used for acquiring an OFDM signal to be transmitted, and performing phase rotation on each subcarrier in each frame of data of the OFDM signal to be transmitted by using a plurality of phase rotation values generated by the phase rotation value module to obtain the OFDM signal after phase rotation, wherein each subcarrier respectively and correspondingly uses different phase rotation values;
and the sending module is used for converting the OFDM signals after the phase rotation into signals with required formats and sending the signals.
A quadrature multicarrier receiving apparatus based on random phase rotation, comprising:
the receiving module is used for receiving the transmitted OFDM signals, and converting the OFDM signals into baseband data after preprocessing;
a recovery module, configured to obtain a key from the baseband data and recover the phase rotation table using the obtained key;
the de-rotation module is used for performing phase de-rotation on each subcarrier data in the baseband data by using the recovered phase rotation table to obtain de-rotated data;
and the demodulation module is used for demodulating the data after the de-rotation.
Compared with the prior art, the invention has the advantages that:
1. when the transmitting end transmits the OFDM signal, each subcarrier in each frame of data of the OFDM signal is subjected to phase rotation by using a randomly generated phase rotation value, namely, each subcarrier is subjected to random phase rotation, so that the carrying data of each subcarrier is superposed with a random phase rotation value, the phase rotation value of each subcarrier is close to pseudo-random and is equivalent to pseudo-randomization of a phase sequence of the carrying data, and therefore, a non-target receiving end is difficult to demodulate, demodulation judgment of the non-target receiving end can be effectively prevented, the capability of resisting the demodulation judgment of the communication signal of the OFDM system is improved, and the safe communication of a physical layer is realized.
2. The invention further performs phase rotation on the pilot channel, so that carrier synchronization is difficult to perform when the pilot channel is detected, the difficulty of detection is increased, and meanwhile, the complexity of detection and demodulation judgment can be further improved and the performance of resisting the detection and the demodulation judgment can be improved by combining the phase rotation of the key channel.
3. The invention further selects the optimal phase rotation table according to the effect after rotation during each rotation, thereby ensuring the transmission safety and reliability and ensuring the signal transmission quality.
Drawings
Fig. 1 is a schematic flow chart of an implementation of the orthogonal multi-carrier transmission method based on random phase rotation according to the present embodiment.
Fig. 2 is a schematic diagram illustrating a principle of generating a phase rotation value in the present embodiment.
Fig. 3 is a schematic diagram of two arrangement principles of the key channel in the embodiment.
Fig. 4 is a schematic diagram comparing an OFDM signal obtained by the method of the present invention with a conventional OFDM signal in a specific application embodiment.
Fig. 5 is a schematic diagram of a system structure for implementing OFDM signal communication transmission in this embodiment.
Detailed Description
The invention is further described below with reference to the drawings and specific preferred embodiments of the description, without thereby limiting the scope of protection of the invention.
As shown in fig. 1, the steps of the orthogonal multi-carrier transmission method based on random phase rotation in the present embodiment include:
s01, randomly generating a plurality of phase rotation values by using a secret key in advance;
s02, performing phase rotation on each subcarrier in each frame of data of an OFDM signal to be transmitted by using a plurality of pre-generated phase rotation values to obtain the phase-rotated OFDM signal, wherein each subcarrier respectively uses different phase rotation values correspondingly;
and S03, processing the OFDM signal after phase rotation into a signal with a required format and then sending out the signal.
In this embodiment, when the transmitting end transmits the OFDM signal, each subcarrier in each frame of data of the OFDM signal is phase-rotated using a randomly generated phase rotation value, that is, each subcarrier is phase-rotated randomly, so that a random phase rotation value is superimposed on the carrying data of each subcarrier, and the phase rotation value of each subcarrier is close to pseudo-random, which is equivalent to pseudo-randomizing a phase sequence of the carrying data, thereby making it difficult for a non-destination receiving end to demodulate, effectively preventing demodulation decision by the non-destination receiving end, improving the capability of the OFDM system communication signal to resist demodulation decision, and implementing physical layer secure communication.
The plurality of phase rotation values generated as described above form a phase rotation table in a list format, and each phase rotation value in the phase rotation table performs random phase rotation for a different subcarrier. It is understood that the plurality of phase rotation values required for each frame of data may be stored and called in the form of data sets, data structures, etc. according to actual requirements.
In this embodiment, specifically, at the transmitting end, the OFDM signal is divided into frames, each frame includes G OFDM symbols, each OFDM symbol carries data by N subcarriers, and then, G · N subcarriers are required to perform random phase rotation, and a phase rotation table is used to perform phase rotation operation on G · N subcarrier data of each frame, so as to achieve randomized phase rotation on each subcarrier, and a constellation diagram of each symbol is controllable and randomized, which can significantly improve the difficulty of being detected and demodulated.
As shown in fig. 2, in step S01 of this embodiment, the phase rotation table is specifically generated by a key input pseudo random sequence generator, and the pseudo random sequence generator may be implemented by using a shift register according to the pseudo random sequence principle such as m-sequence; after generating the pseudo-random sequence, dividing the pseudo-random sequence into G.N data { zkK is 0, …, G · N-1, yielding G · N phase rotation values:
wherein, G is the number of OFDM symbols in the OFDM signal, and N is the number of subcarriers in each OFDM symbol.
The minimum step of the phase rotation value obtained by the above equation (1) is Δ ═ 2 pi/2QBy adjusting the magnitude of Q, the problem of excessive timing error caused by random phase rotation values can be avoided. Each phase rotation table may generate G · N phase rotation values to correspond to subcarriers in each frame of data one to one, or may generate phase rotation values greater than G · N, and then select G · N phase rotation values from all the phase rotation values to perform phase rotation on each subcarrier.
Further, the phase rotation table is correspondingly generated by the phase rotation value as follows:
in this embodiment, when the sender transmits each frame of data, step S01 generates a phase rotation table by using the pseudo-random sequence generator according to the key, where the phase rotation table includes phase rotation values for G · N subcarrier data; and step S02, performing phase rotation on each subcarrier data according to the phase rotation table, wherein the conversion processing in step S03 specifically includes performing IDFT processing, adding cyclic prefix, parallel-to-serial conversion, and the like, that is, after the phase-rotated signal is sequentially subjected to IDFT processing, cyclic prefix adding, parallel-to-serial conversion, the signal is sent out through up-conversion. In step S03, other types of transformation processing may be adopted according to actual requirements to form signals with a required format for transmission, so as to meet the requirements of different applications.
In step S02, the method further includes using part of the subcarriers in the OFDM signal as a key channel for transmitting a key, and performing phase rotation on the key channel and a pilot channel in the OFDM signal. The phase rotation is carried out on the pilot frequency channel, so that the carrier synchronization is difficult to carry out when the pilot frequency channel is detected, the difficulty of the detected pilot frequency channel is increased, the complexity of the detected and demodulated judgment can be further improved by combining the phase rotation of the key channel and the pilot frequency channel, and the performance of resisting the detected and demodulated judgment is greatly improved. After the phase rotation is performed on the key channel and the pilot channel at the transmitting end, the phase de-rotation operation is performed on the pilot data and the key data at the receiving end, and then the carrier recovery and the key demodulation operation are performed. Of course, the above may also be performed by phase rotating only one of the pilot channel and the key channel according to actual requirements.
In a specific embodiment, for OFDM signals, each OFDM symbol is composed of N subcarriers, one frame of data is composed of G OFDM symbols, wherein there are several pilot signals and several subcarriers for transmitting the key channel, and most of the remaining subcarriers are used for transmitting information data. A specific key channel may be configured to cover all subcarriers as much as possible in a frame OFDM, so that even if deep fading occurs in individual subcarriers, normal transmission of most key data is not affected.
In this embodiment, the key channels may be specifically configured to be arranged according to a preset rule to form a regular arrangement, that is, the positions of all the key channels in the OFDM data frame are fixed, and the positions are defined in advance by the transceiver. In a specific application embodiment, as shown in fig. 3(a), the key channels may be regularly arranged on the diagonal. The key channel may also be configured to be arranged in a random permutation, with permutation positions randomly generated based on the key. In a specific application embodiment, the key channel is a random permutation as shown in fig. 3(b), wherein the permutation position can also be generated by the key through the pseudo random number generator, and the key data positions of adjacent frames are different.
The random phase rotation table corresponding to the pseudo random number generated by using the key and the random arrangement mode of the key channel may be generated by the same key, or may be generated by different keys. On the basis of carrying out random phase rotation on each frame of subcarrier by using the key, the keys used by the key channel are randomly arranged, so that under the condition of not knowing the key, key data cannot be obtained, and further the position of the subcarrier carrying the key data cannot be obtained, so that correct phase derotation operation and subsequent subcarrier data demodulation judgment cannot be realized, and therefore demodulation by a non-target receiver can be ensured, and the safety of OFDM signal transmission is further improved.
In step S02 of the present embodiment, each frame of data is phase-rotated for each subcarrier using a phase rotation table generated by a different key; in step S03, the key of the next frame data is transmitted simultaneously with the transmission of the current frame data. That is, each frame uses different keys to randomly generate a phase rotation table, each subcarrier in each frame of data uses different phase rotation values in the phase rotation table, and the keys can be specifically transmitted by sending the next frame of keys in the frame, so that the processing delay requirement can be obviously reduced.
In a specific application embodiment, a sending end transmits key data on different subcarriers of a plurality of OFDM symbols within a frame time, and transmits a key of next frame data in a current frame; after receiving the data sent by the sending end, the receiving end locally recovers the phase rotation table according to the key received in the previous frame, and then performs phase derotation and demodulation judgment on each subcarrier data according to the phase rotation table. According to the mode, under the fastest condition, each frame time only comprises one OFDM time period, so that the key can be changed in each OFDM symbol period, the demodulation judgment of the OFDM symbols for a non-target receiving end without the key is almost impossible, and the safety and reliability of OFDM signal transmission can be greatly improved.
In step S03 of this embodiment, the method further includes performing error correction coding on the key to be sent, converting the key into key data, and sending the key data, so as to prevent a key transmission error. Specifically, each L-bit key is subjected to error correction coding at a sending end, and is converted into P-bit key data for transmission; after receiving the data sent by the sending end, the receiving end obtains the key from the key data through error correction decoding, and therefore the key transmission error is avoided. The error correction coding and decoding can be realized by adopting (P, L) block codes and other modes.
In the specific application embodiment, the keys of the adjacent frames correspond to different states of the same pseudorandom sequence generator, and can be realized by searching, because the keys of the adjacent frames are different states of the same pseudorandom sequence generator, under the condition of correctly obtaining the key of the previous frame, the local pseudorandom sequence generator is operated for G.N times, so that the key of the frame can be obtained, and even if a large number of error codes cause that error correction decoding cannot correct all error codes of the key, the local pseudorandom sequence generator can be used for searching front and back, so that the error code resistance of the key can be obviously improved by combining error correction coding decoding and front and back searching of the pseudorandom sequence.
Furthermore, the verification code can be transmitted on the specified subcarrier according to actual requirements to verify whether the key is normally obtained, and the receiving end judges whether the key is normally obtained through the received verification code.
Further, in this embodiment, a plurality of phase rotation tables are generated in advance by using a plurality of different keys, and an optimal phase rotation table is selected from the plurality of phase rotation tables according to the effect after phase rotation for each frame of data, so that each subcarrier in the current frame is subjected to phase rotation by using a plurality of phase rotation values in the optimal phase rotation table. The optimal phase rotation table is selected according to the effect after rotation during each rotation, so that the transmission safety and reliability can be ensured, and the signal transmission quality can be ensured.
In a specific application embodiment, it is preferable to select an optimal phase rotation table according to a lowest peak-to-average power ratio (PAPR) that can be achieved after phase rotation, that is, at a sending end, when rotating each time, a plurality of keys are selected to generate a plurality of phase rotation tables in parallel, and after preprocessing is performed on the same frame of data, the phase rotation table that can achieve the lowest PAPR is selected as the optimal phase rotation table to control the phase rotation of the frame of data. And at the receiving end, the key search and the phase derotation operation are realized through the parallel search of a plurality of phase rotation tables.
In order to verify the effectiveness of the present invention, in the specific application embodiment, the method of the present invention is used to form a random phase rotation OFDM signal and compare the random phase rotation OFDM signal with a conventional OFDM signal, and in the case that each subcarrier is modulated by 16QAM, I/Q scatter diagrams of baseband data of the random phase rotation OFDM signal and the conventional OFDM signal are respectively shown in fig. 4, where fig. 4(a) corresponds to a classical OFDM signal, and fig. 4(b) corresponds to an OFDM signal after the random phase rotation of the present invention. As can be seen from fig. 4, the subcarrier modulation of the conventional OFDM signal can easily identify the binary number, and the random phase rotation OFDM signal cannot identify the modulated binary number on each subcarrier, so that the subsequent demodulation decision cannot be performed, that is, the method of the present invention has the performance of resisting the demodulation decision, and can implement the physical layer secure communication.
This embodiment is applied to the receiving method of the above sending method, and includes the steps of:
SA1, receiving an OFDM signal sent by a sending end, converting the OFDM signal into baseband data after conversion;
SA2, recovering a phase rotation table from the baseband data, and performing phase derotation on each subcarrier data in the baseband data by using the phase rotation table to obtain derotated data;
and SA3, performing demodulation judgment on the data after the de-rotation.
In this embodiment, after DFT conversion is performed on each OFDM symbol to obtain baseband data, a phase rotation table of a current frame is restored by using a key obtained from the previous frame of OFDM data without performing demodulation decision at a receiving end, and then phase derotation operations are performed on G · N subcarrier data, followed by subsequent demodulation decision; the data in the demodulation decision contains key data, and the receiving end performs error correction decoding on the key data to obtain a key required by next frame phase derotation, so that only the receiving end matched with the transmitting end can correctly demodulate the OFDM signal, and other non-target receiving ends cannot correctly demodulate the OFDM signal.
In order to implement the foregoing method, the orthogonal multi-carrier transmitting apparatus based on random phase rotation in this embodiment includes:
a phase rotation table module for randomly generating a plurality of phase rotation values using the secret key;
the phase rotation module is used for acquiring an OFDM signal to be transmitted, and performing phase rotation on each subcarrier in each frame of data of the OFDM signal to be transmitted by using a plurality of phase rotation values generated by the phase rotation value module to obtain the OFDM signal after phase rotation, wherein each subcarrier respectively uses different phase rotation values correspondingly;
and the sending module is used for converting the OFDM signals after the phase rotation into signals with required formats and sending the signals.
As shown in fig. 5, at the transmitting end, the phase rotation table module includes a phase rotation table, where the phase rotation table includes a plurality of phase rotation values generated randomly by using a key, the phase rotation values are as shown in formula (1), the pilot data and the information data are OFDM-blocked to form an OFDM signal, the phase rotation table module receives the OFDM signal and the key data after error correction coding, each subcarrier in each frame of data of the OFDM signal is phase-rotated by using the phase rotation value in the phase rotation table, the phase-rotated signal is transmitted after being subjected to N-point IDFT, cyclic prefix addition and serialization processing, and the key data of the next frame is transmitted at the same time.
The transmitting apparatus of this embodiment corresponds to the transmitting method, and is not described in detail herein.
The orthogonal multi-carrier receiving device based on random phase rotation in the embodiment comprises:
the receiving module is used for receiving the transmitted OFDM signals, and converting the OFDM signals into baseband data after conversion;
the de-rotation module is used for recovering the phase rotation table from the baseband data and respectively performing phase de-rotation on each subcarrier data in the baseband data by using the phase rotation table to obtain de-rotated data;
and the demodulation unit is used for demodulating the data after the derotation.
As shown in fig. 5, at the receiving end, the receiving module includes a serial-parallel conversion unit, a cyclic prefix removal unit, and an N-point DFT unit, which are connected in sequence, to perform serial-parallel conversion, cyclic prefix removal, and N-point DFT calculation on the received OFDM data sent by the sending end in sequence, so as to obtain a baseband signal, recover key data from data obtained from a previous frame for the baseband signal, obtain a key of a current frame through error correction and decoding, recover a phase rotation table using the key, perform phase derotation on each subcarrier data in the baseband data using the phase rotation table, and input the data after derotation into the OFDM deblocking for demodulation.
The receiving apparatus of this embodiment corresponds to the receiving method, and is not described in detail herein.
The foregoing is considered as illustrative of the preferred embodiments of the invention and is not to be construed as limiting the invention in any way. Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention should fall within the protection scope of the technical scheme of the present invention, unless the technical spirit of the present invention departs from the content of the technical scheme of the present invention.
Claims (10)
1. An orthogonal multi-carrier transmission method based on random phase rotation, the transmission method comprising:
obtaining an OFDM signal to be transmitted, and performing phase rotation on each subcarrier in each frame of data of the OFDM signal to be transmitted by using a plurality of pre-generated phase rotation values to obtain the OFDM signal after phase rotation, wherein the phase rotation values are randomly generated by using a secret key, and each subcarrier respectively and correspondingly uses different phase rotation values;
and converting the OFDM signal after the phase rotation into a signal with a required format and then sending the signal.
2. The orthogonal multicarrier transmission method according to claim 1, wherein the pre-generated pseudo-random sequence is divided into G · N data { zz ] according to Q bitskK is 0, …, G · N-1, yielding G · N phase rotation values:
wherein, G is the number of OFDM symbols in the OFDM signal, and N is the number of subcarriers in each OFDM symbol.
3. The orthogonal multi-carrier transmission method based on random phase rotation as claimed in claim 1, further comprising using part of sub-carriers in the OFDM signal to be transmitted as a key channel for transmitting the key, and performing phase rotation on a pilot channel and/or the key channel before transmitting the OFDM signal to be transmitted.
4. The orthogonal multi-carrier transmission method based on random phase rotation according to claim 3, wherein: the key channels are configured to be arranged according to a preset rule to form a regular arrangement, or are configured to be arranged in a random arrangement mode according to an arrangement position generated by a key at random.
5. The orthogonal multi-carrier transmission method based on random phase rotation according to any one of claims 1 to 4, wherein: when each sub-carrier in each frame of data of the OFDM signal to be transmitted is subjected to phase rotation, specifically, each frame of data uses a phase rotation table generated by different keys to perform phase rotation on each sub-carrier, the phase rotation table comprises a plurality of phase rotation values, and when current frame data is transmitted, a key of the next frame data is transmitted at the same time.
6. The orthogonal multi-carrier transmission method based on random phase rotation according to claim 5, wherein: and generating a plurality of phase rotation tables by using a plurality of different keys in advance, and selecting an optimal phase rotation table from the plurality of phase rotation tables according to the effect of phase rotation of each frame of data so as to perform phase rotation on each subcarrier in the current frame by using a plurality of phase rotation values in the optimal phase rotation table.
7. The orthogonal multi-carrier transmission method based on random phase rotation according to any one of claims 1 to 4, wherein when the OFDM signal after phase rotation is transformed into a signal of a desired format and then transmitted, the method further comprises performing error correction coding on each key, converting the key into key data and then transmitting the key data.
8. A receiving method for the transmission method according to any one of claims 1 to 7, characterized by comprising the steps of:
receiving OFDM signals sent by a sending end, and transforming the OFDM signals into OFDM data after preprocessing;
acquiring a key from the OFDM data and recovering the phase rotation table by using the acquired key;
respectively carrying out phase derotation on each subcarrier data in the OFDM data by using the recovered phase rotation table to obtain derotated data;
and demodulating the data after the de-rotation.
9. An orthogonal multicarrier transmission apparatus based on random phase rotation, comprising:
a phase rotation value module for randomly generating a plurality of phase rotation values using the secret key;
the phase rotation module is used for acquiring an OFDM signal to be transmitted, and performing phase rotation on each subcarrier in each frame of data of the OFDM signal to be transmitted by using a plurality of phase rotation values generated by the phase rotation value module to obtain the OFDM signal after phase rotation, wherein each subcarrier respectively and correspondingly uses different phase rotation values;
and the sending module is used for converting the OFDM signals after the phase rotation into signals with required formats and sending the signals.
10. An orthogonal multi-carrier receiving apparatus based on random phase rotation, comprising:
the receiving module is used for receiving the transmitted OFDM signals, and converting the OFDM signals into baseband data after preprocessing;
a recovery module, configured to obtain a key from the baseband data and recover the phase rotation table using the obtained key;
the de-rotation module is used for performing phase de-rotation on each subcarrier data in the baseband data by using the recovered phase rotation table to obtain de-rotated data;
and the demodulation module is used for demodulating the data after the de-rotation.
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