A method, system, electronic device, and medium for constructing integrated communication and conduction signals based on OFDM.

Abstract

This invention belongs to the field of satellite communication and navigation technology, specifically relating to a method, system, electronic device, and medium for constructing an integrated communication and navigation signal based on OFDM. The construction method includes: constructing a reference signal, called MLBOC, which combines a hybrid linear offset carrier and a binary offset carrier, thereby improving the signal's navigation performance; then, embedding the MLBOC into the OFDM communication signal to generate a novel integrated communication and navigation signal, OFDM-M. The parameters of OFDM-M are configured for optimal communication and navigation performance. Simulation experiments show that, compared with other ICAN signals, the proposed OFDM-M signal has superior communication and navigation performance.

Description

Technical Field

[0001] This invention belongs to the field of satellite communication and navigation technology, specifically relating to an OFDM-based integrated communication and navigation signal construction method, system, electronic device, and medium. Background Technology

[0002] In recent years, Low-Earth Orbit (LEO) constellations have flourished, primarily designed to provide broadband internet communication services, while also offering opportunities to enhance the positioning, navigation, and timing services of Global Navigation Satellite Systems (GNSS). Many studies utilize communication signals broadcast by LEO constellations as opportunistic signals to provide navigation services; however, without authorization from LEO satellite operators, opportunistic navigation is non-cooperative and has low accuracy. Cooperative navigation modes can effectively address this problem, allowing cooperative users to easily obtain precise orbits and signal structures of LEO satellites and activate satellite signals according to their needs, thereby improving navigation accuracy. Therefore, researching the design of LEO satellite transmission signals is crucial for LEO constellations to provide Integrated Communication and Navigation (ICAN) services.

[0003] Orthogonal Frequency Division Multiplexing (OFDM), a high-performance modulation technique, has been used in the downlink signals of the Starlink low-Earth orbit constellation. Some studies have attempted to design integrated communication and navigation signals based on OFDM. For example, by superimposing navigation signals onto OFDM communication signals using time division and code division multiplexing, Time Division Code Division OFDM (TC-OFDM) technology has been developed. Furthermore, by shifting the frequency of navigation signals to the sidebands of OFDM communication signals using frequency division multiplexing, Binary Offset Carrier (BOC) assisted OFDM (BA-OFDM) technology has been developed.

[0004] The existing OFDM-type integrated communication and navigation signal design has several limitations: (1) No research has been conducted on using the navigation signal as the OFDM reference signal. The existing reference signal is designed for channel estimation, and its navigation performance is not optimal; (2) Existing research mainly uses time division, frequency division or code division to multiplex separately designed communication and navigation signals. There is mutual interference between the communication and navigation signals, and the compatibility is poor. Summary of the Invention

[0005] The purpose of this invention is to provide a method, system, electronic device and medium for constructing integrated communication and navigation signals based on OFDM, which solves the limitations of existing integrated communication and navigation signals based on OFDM.

[0006] This invention is achieved through the following technical solution:

[0007] This invention discloses a method for constructing an integrated communication and conduction signal based on OFDM, comprising the following steps:

[0008] S1. Construct a reference signal that combines a linear offset carrier and a binary offset carrier, called the MLBOC signal;

[0009] S2. Embed the MLBOC signal into the OFDM communication signal to generate the integrated communication and navigation signal OFDM-M.

[0010] Furthermore, assume that the number of subcarriers in the OFDM communication signal is... Subcarrier number from arrive The subcarrier frequency spacing is ;

[0011] In S1, the MLBOC signal The expression is:

[0012]

[0013] in, It is the symbol time of OFDM; n Symbol number representing OFDM; k Indicates the subcarrier number; t Indicates a specific moment in time; Indicates the reference signal at the 1st n Within the time of the first symbol, the... k The modulated data on each subcarrier is a predefined pseudo-random sequence; Reference data The set of locations; The support time is The rectangle function, It is k Expressions for subcarrier waveforms.

[0014] further, Abbreviated as , It is a rectangle function, defined as:

[0015] .

[0016] further, Abbreviated as , It is the first one with two forms of expression k The waveforms of each subcarrier are used. The subcarrier waveform with the smaller absolute value of its number is represented by LOC, and the subcarrier waveform with the larger absolute value of its number is represented by BOC. The specific expression is as follows:

[0017]

[0018] in, It is a threshold index. Represents the imaginary unit. It is a symbolic function. This indicates the subcarrier frequency interval.

[0019] further, Values ,in This represents the function for rounding up.

[0020] Furthermore, S2 specifically involves: by replacing the traditional OFDM reference signal with an MLBOC signal, a new multicarrier modulation scheme is established, resulting in OFDM with an MLBOC signal, referred to as OFDM-M, denoted as:

[0021]

[0022] in, Represents communication signals, This indicates the replaced reference signal.

[0023] Furthermore, the power spectral density of the MLBOC signal is denoted as... , is the sum of the power spectral densities of all subcarriers, expressed as:

[0024]

[0025] in, f It is the frequency independent variable. It is k Power spectral density of each subcarrier;

[0026] MLBOC signals have two types of subcarrier waveforms: LOC and BOC. The power spectral density of the subcarriers is divided into two categories:

[0027]

[0028] in, f Represents the frequency independent variable. It is k Power spectral density of each LOC subcarrier It is k Power spectral density of each BOC subcarrier;

[0029] It is k The spectrum of subcarriers of type LOC, It is k The spectrum of a BOC-type subcarrier;

[0030] It is the chip duration of the pseudo-random sequence, which is equal to in OFDM-M signals. ;

[0031] It is a threshold index. k This indicates the subcarrier number.

[0032] This invention also discloses an OFDM-based integrated signal construction system for communication and conduction, comprising:

[0033] The reference signal construction module is used to construct a reference signal that combines a linear offset carrier and a binary offset carrier, called an MLBOC signal.

[0034] The signal embedding module is used to embed the MLBOC signal into the OFDM communication signal to generate the integrated communication and navigation signal OFDM-M.

[0035] The present invention also discloses a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the OFDM-based integrated signal construction method.

[0036] The present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the OFDM-based integrated signal construction method.

[0037] Compared with the prior art, the present invention has the following beneficial technical effects:

[0038] This invention proposes a method for constructing an integrated communication and navigation signal based on OFDM. By designing the OFDM reference signal, it enables its use for both communication signal synchronization and channel equalization, as well as navigation signal acquisition and tracking, thus simultaneously achieving excellent communication and navigation performance. In this novel ICAN signal design, the reference signal is constructed by mixing a linear offset carrier (LOC) and a binary offset carrier (BOC), abbreviated as MLBOC. Embedding the BOC, commonly used in navigation signal design, into the reference signal enhances its navigation performance. Then, combining the OFDM communication signal with the MLBOC reference signal generates this novel ICAN signal, called OFDM-M. The OFDM-M signal proposed in this invention combines the OFDM communication signal and the MLBOC reference signal without conflict, eliminating mutual interference and improving the compatibility between communication and navigation signals. This provides a pioneering multiplexing method for ICAN signals. Furthermore, the main difference between OFDM-M signals and standard OFDM communication signals lies in the reference signal. The two maintain good compatibility, and OFDM-M signals can be easily upgraded by changing the standard OFDM signal. Attached Figure Description

[0039] Figure 1 Resource grid for OFDM signals;

[0040] Figure 2 Normalized (a) autocorrelation function and (b) power spectral density of MLBOC signal;

[0041] Figure 3 The curve showing the change in BER as a function of LEO satellite transmission power;

[0042] Figure 4 The curve shows the variation of ranging accuracy with LEO satellite transmission power;

[0043] Figure 5 Bit error rate curves for different ICAN signals;

[0044] Figure 6 For NELP code tracking errors of different ICAN signals;

[0045] Figure 7 This is a flowchart of an OFDM-based integrated signal construction method according to the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0047] The components described and illustrated in the accompanying drawings and embodiments of this invention can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment of the invention. All other embodiments obtained by those skilled in the art based on the accompanying drawings and embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0048] It should be noted that the terms “comprising,” “including,” or any other variations are intended to cover non-exclusive inclusion, such that a process, element, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to the process, element, method, article, or apparatus.

[0049] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0050] Example 1

[0051] like Figure 7 As shown, this invention discloses a method for constructing an integrated communication and conduction signal based on OFDM, comprising the following steps:

[0052] S1. Construct a reference signal that combines a linear offset carrier and a binary offset carrier, called the MLBOC signal;

[0053] S2. Embed the MLBOC signal into the OFDM communication signal to generate the integrated communication and navigation signal OFDM-M.

[0054] The OFDM-M signal proposed in this invention is a non-conflicting combination of OFDM communication signals and MLBOC reference signals, with no mutual interference between them. This improves the compatibility between communication and navigation signals, providing a pioneering multiplexing method for ICAN signals. Furthermore, the main difference between the OFDM-M signal and the standard OFDM communication signal lies in the reference signal; both maintain good compatibility, and the standard OFDM signal can be easily upgraded to an OFDM-M signal by modifying it.

[0055] Example 2

[0056] The following section details the construction method of the reference signal MLBOC and some of its details.

[0057] Assume the number of subcarriers in the OFDM communication signal is Subcarrier number from arrive The subcarrier frequency spacing is The resource grid is the core of the OFDM signal, representing the composition of the modulated data on each carrier at each time point: communication data or reference signals, such as... Figure 1 As shown. (Using...) Reference data The set of locations, Indicates the reference signal at the 1st n Within the time of the first symbol, the... k The modulation data on each subcarrier is a predefined pseudo-random sequence.

[0058] Traditional OFDM reference signals are designed for channel estimation and equalization. To enhance navigation performance, this invention proposes a novel OFDM reference signal, abbreviated as MLBOC, which represents a hybrid of linear offset carrier (LOC) and binary offset carrier (BOC), and can be expressed mathematically as follows:

[0059] (1)

[0060] in, It is the symbol time of OFDM; n Symbol number representing OFDM; k Indicates the subcarrier number; t It indicates a specific moment in time. Indicates the reference signal at the 1st n Within the time of the first symbol, the... k The modulated data on each subcarrier is a predefined pseudo-random sequence; Reference data The set of locations. The support time is The rectangle function, It is k Expressions for subcarrier waveforms.

[0061] Abbreviated as , It is a rectangle function, defined as:

[0062] (2)

[0063] Specifically, The corresponding abbreviation is: , It is the first one with two forms of expression k The waveforms of the subcarriers are categorized by their absolute numbers: the subcarrier waveform with the smaller absolute number uses the LOC (Lowest Common Coefficient) designation, and the subcarrier waveform with the larger absolute number uses the BOC (Best Common Coefficient) designation. The specific expression is as follows:

[0064] (3)

[0065] in, It is a threshold index; Represents the imaginary unit; It is a symbolic function; This indicates the subcarrier frequency interval.

[0066] Example 3

[0067] The following is a detailed introduction to threshold indexes. Discussion of possible values.

[0068] This invention selects based on two factors: navigation tracking accuracy and communication performance. The optimal value. On the one hand, when When the number of BOC subcarriers is reduced, the tracking accuracy increases accordingly; on the other hand, in order to ensure communication performance, It cannot be reduced indefinitely because when the harmonics of the BOC subcarrier overlap with the frequency of another subcarrier of the OFDM signal, it will interfere with the communication signal, leading to a decrease in the bit error rate. If the minimum index of the BOC subcarrier in the MLBOC signal is... Fourier analysis shows that the minimum harmonic frequency of the MLBOC signal is... To avoid interference with other subcarriers, the harmonics of the MLBOC signal should be outside the main lobe bandwidth of the OFDM signal. That is, its minimum frequency should be greater than the maximum frequency of the subcarrier.

[0069] (4)

[0070] in This represents the maximum index of the subcarrier.

[0071] Therefore, to avoid subcarrier interference, the following is derived from formula (4): The following conditions must be met:

[0072] (5)

[0073] in This represents the function for rounding up.

[0074] Based on the above analysis, the present invention will The value is set to This allows the signal to have optimal communication and navigation performance.

[0075] Example 4

[0076] The following section details the construction method of the ICAN signal OFDM-M and some of its details.

[0077] By replacing the traditional OFDM reference signal with an MLBOC signal, a new multicarrier modulation scheme can be established, namely OFDM with an MLBOC signal, called OFDM-M, which can be represented mathematically as follows:

[0078] (6)

[0079] in, Represents communication signals, This indicates the replaced reference signal.

[0080] OFDM-M and OFDM have essentially similar signal structures. OFDM-M can be obtained by modifying the subcarrier waveform of the OFDM reference signal. Therefore, OFDM-M has good compatibility with OFDM. Furthermore, due to the use of MLBOC, OFDM-M has higher navigation accuracy than OFDM, while also improving channel estimation quality and reducing the bit error rate.

[0081] Example 5

[0082] The power spectral density of the MLBOC signal is described in detail below.

[0083] Power spectral density is an important tool for analyzing the navigation performance of reference signals. This invention derives the power spectral density of the MLBOC signal. The MLBOC signal uses a pseudo-random sequence to ensure that all subcarriers are orthogonal over a long integration time. Therefore, the power spectral density of the MLBOC signal is denoted as... It is the sum of the power spectral densities of all subcarriers, i.e.

[0084] (7)

[0085] in, f It is the frequency independent variable. It is k The power spectral density of each subcarrier can be obtained from the power spectral density of the pseudo-random sequence. and the spectrum of subcarrier waveforms It is deduced that:

[0086] (8)

[0087] in, It is the chip duration of the pseudo-random sequence, which in OFDM-M is equal to When the pseudo-random sequence is an ideal white noise sequence, .

[0088] For the k Subcarriers of type LOC, their spectrum for:

[0089] (9)

[0090] in, It is k The frequency of each subcarrier This represents the sinc function. Represents the imaginary unit; It is the chip duration of the pseudo-random sequence.

[0091] Similarly, the first k Spectrum of BOC type subcarriers for:

[0092] (10)

[0093] in, It is k The frequency of each subcarrier; It is the chip duration of the pseudo-random sequence.

[0094] Since MLBOC signals have two types of subcarrier waveforms, LOC and BOC, the power spectral density of the subcarriers is divided into two categories:

[0095] (11)

[0096] in, and They are the first k Power spectral density of each LOC and BOC subcarrier.

[0097] like Figure 2 As shown, a schematic diagram of the normalized autocorrelation function and power spectral density of an MLBOC signal is presented. From Figure 2 As can be seen, the properties of the MLBOC signal are similar to those of the standard OFDM reference signal, indicating that the OFDM-M signal has good compatibility with the standard OFDM signal.

[0098] The following section describes the performance analysis of the OFDM-M signal designed in the final version of this invention.

[0099] (I) Performance Comparison of OFDM-M and OFDM Signals

[0100] To illustrate the advantages of OFDM-M signals compared to traditional OFDM signals, their communication and navigation performance were compared. The reception of both signals used the same method: the signal synchronization module utilized a delay lock loop (DLL) to achieve communication synchronization and navigation delay estimation.

[0101] (1) Communication performance

[0102] This invention uses the bit error rate (BER) to evaluate the communication performance of two signals, and the results are as follows: Figure 3 As shown. From Figure 3 The following conclusions can be drawn: the BER curve of OFDM-M signal is below that of traditional OFDM signal. When the transmit power is 60 dBm, the BER of OFDM-M signal is reduced by 10% compared with OFDM signal, indicating that OFDM-M signal has better communication reliability.

[0103] (2) Navigation performance

[0104] Time delay estimation error To characterize navigation performance, one can derive the estimated time delay. and actual time delay It is deduced that:

[0105] (12)

[0106] This invention utilizes estimation error The standard deviation (STD) is used to compare the navigation performance of OFDM-M signals and OFDM signals. The results are as follows: Figure 4 As shown. From Figure 4 The following conclusions can be drawn: Compared with traditional OFDM signals, OFDM-M signals have a significantly lower estimation error (STD). When the transmit power is 60 dBm, the STD of OFDM-M signals is 24% lower than that of traditional OFDM signals, indicating that OFDM-M signals have better navigation accuracy.

[0107] (II) Comparison of OFDM-M signals with other ICAN signals

[0108] This invention compares OFDM-M signals with other OFDM-type ICAN signals, such as TC-OFDM and BA-OFDM, to demonstrate the advantages of OFDM-M. For a fair comparison, TC-OFDM, BA-OFDM, and OFDM-M all employ the same receiver architecture, and these ICAN signals have the same main lobe bandwidth, OFDM configuration parameters, and transmission power.

[0109] (1) Communication performance

[0110] The relationship between the bit error rate of the three signals and the satellite transmit power is as follows: Figure 5 As shown. From Figure 5 The following conclusions can be drawn: compared with TC-OFDM, OFDM-M signal has a lower bit error rate; compared with BA-OFDM, the bit error rate of OFDM-M signal is similar, indicating that OFDM-M has good communication reliability.

[0111] (2) Navigation performance

[0112] Navigation performance can be evaluated by tracking accuracy, and NELP code tracking error is used to further evaluate tracking accuracy. The calculation results of NELP code tracking error are as follows: Figure 6 As shown, from Figure 6 The following conclusions can be drawn: The proposed OFDM-M signal has the lowest code tracking error and the highest tracking accuracy. When the transmit power is 60 dBm, OFDM-M reduces the code tracking error by 90.8% and 49.6% respectively compared with TC-OFDM and BA-OFDM.

[0113] In summary, compared with the existing ICAN signal, the OFDM-M signal proposed in this invention has better communication and navigation performance.

[0114] This invention also discloses a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the OFDM-based integrated signal construction method. The memory may include main memory, such as high-speed random access memory, or it may also include non-volatile memory, such as at least one disk storage device. The processor, network interface, and memory are interconnected via an internal bus, which may be an industry-standard architecture bus, a peripheral component interconnection standard bus, an extended industry-standard architecture bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. The memory stores the program; specifically, the program may include program code, which includes computer operation instructions. The memory may include main memory and non-volatile memory, and provides instructions and data to the processor.

[0115] This invention also discloses a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the steps of the OFDM-based integrated signal construction method. Specifically, the computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. The volatile memory may include random access memory and / or cache memory, etc. The non-volatile memory may include read-only memory, hard disk, flash memory, optical disk, magnetic disk, etc.

[0116] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, etc.) containing computer-usable program code.

[0117] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0118] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0119] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for constructing an integrated communication and conduction signal based on OFDM, characterized in that, Includes the following steps: S1. Construct a reference signal that combines a linear offset carrier and a binary offset carrier, called the MLBOC signal; S2. Embed the MLBOC signal into the OFDM communication signal to generate the integrated communication and navigation signal OFDM-M; Assume the number of subcarriers in the OFDM communication signal is Subcarrier number from arrive The subcarrier frequency spacing is ; In S1, the MLBOC signal The expression is: in, It is the symbol time of OFDM; n Symbol number representing OFDM; k Indicates the subcarrier number; t Indicates a specific moment in time; Indicates the reference signal at the 1st n Within the time of the first symbol, the... k The modulated data on each subcarrier is a predefined pseudo-random sequence; Reference data The set of locations; The support time is The rectangle function, It is the first k Expressions for the waveforms of each subcarrier; S2 specifically refers to: by replacing the traditional OFDM reference signal with an MLBOC signal, a new multicarrier modulation scheme is established, resulting in OFDM with an MLBOC signal, called OFDM-M, denoted as: in, Represents communication signals, This indicates the replaced reference signal.

2. The method for constructing an integrated communication and conduction signal based on OFDM according to claim 1, characterized in that, Abbreviated as , It is a rectangle function, defined as: 。 3. The method for constructing an integrated communication and conduction signal based on OFDM according to claim 1, characterized in that, Abbreviated as , It is the first one with two forms of expression k The waveforms of each subcarrier are used. The subcarrier waveform with the smaller absolute value of its number is represented by LOC, and the subcarrier waveform with the larger absolute value of its number is represented by BOC. The specific expression is as follows: in, It is a threshold index. Represents the imaginary unit. It is a symbolic function. This indicates the subcarrier frequency interval.

4. The OFDM-based integrated signal construction method according to claim 3, characterized in that, Values ,in This represents the function for rounding up.

5. The OFDM-based integrated signal construction method according to claim 1, characterized in that, The power spectral density of the MLBOC signal, denoted as , is the sum of the power spectral densities of all subcarriers, expressed as: in, f It is the frequency independent variable. It is the first k Power spectral density of each subcarrier; MLBOC signals have two types of subcarrier waveforms: LOC and BOC. The power spectral density of the subcarriers is divided into two categories: in, f Represents the frequency independent variable. It is the first k Power spectral density of each LOC subcarrier It is the first k Power spectral density of each BOC subcarrier; It is the first k The spectrum of subcarriers of type LOC, It is the first k The spectrum of a BOC-type subcarrier; It is the chip duration of the pseudo-random sequence, which is equal to in OFDM-M signals. ; It is a threshold index. k This indicates the subcarrier number.

6. A communication-conduction integrated signal construction system based on OFDM that implements the communication-conduction integrated signal construction method according to any one of claims 1 to 5, characterized in that, include: The reference signal construction module is used to construct a reference signal that combines a linear offset carrier and a binary offset carrier, known as an MLBOC signal. The signal embedding module is used to embed the MLBOC signal into the OFDM communication signal to generate the integrated communication and navigation signal OFDM-M.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the OFDM-based integrated signal construction method as described in any one of claims 1 to 5.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the OFDM-based integrated signal construction method as described in any one of claims 1 to 5.

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