LFM-BASED MULTI-USER METHOD AND DEVICE FOR IOT TRANSMISSION

Abstract

The present invention discloses a multi-user spatial IoT transmission method based on LFM, configuring corresponding slopes for LFM-modulated time-frequency waveforms for different users in order to determine the modulated signal of any user, wherein the slope configured for said user satisfies a fractional multiplicative slope without changing the frequency spreading factor; determining, on the basis of the phase-frequency relationship, a time-domain signal for the LFM-modulated signal of any user, in order to perform a transmission on the basis of the determined time-domain signal; determining a time-domain signal of the unmodulated and down-chirped LFM signal corresponding to any user;the processing of the time-domain signal from any of said users based on the time-domain signal of said unmodulated and down-chirped LFM signal; the signal obtained after signal processing is subjected to a discrete Fourier transform, which is used to demodulate the signal received from any of the users. To reduce the transmission power demand, obtain low energy consumption, propose a simultaneous multi-user scheme and achieve simultaneous multi-user access and transmission with the same time-frequency resources. [Fig.1];

Description

Title of the invention: LFM-BASED MULTI-USER METHOD AND DEVICE FOR IOT TRANSMISSION technical fields

[0001] The present invention relates to the technical field of communication, and in particular to a multi-user method and device based on LFM for spatial IOT transmission. Basic technology

[0002] IoT applications in various sectors, such as traffic control, smart furniture, telemedicine, and remote sensing surveys, are developing rapidly, as is the scale of the IoT infrastructure. Terrestrial IoT technologies such as NB-IoT, eMTC, and LoRa have also been the subject of extensive research in academia and industry, and they offer certain performance advantages, such as low power consumption, low cost, wide coverage, and high capacity.However, because the construction of base stations is affected by geography, terrestrial networks cannot provide complete coverage in certain environments such as deserts, oceans, and congested cities; on the other hand, the development of many international businesses such as maritime logistics has increased the demand for the extent and continuous coverage capacity of IoT, and exacerbates the tension between the limited capacity of terrestrial IoT and the growing needs for services.

[0003] With the advantages of wide coverage, high capacity, and independence from the geographical environment, space-based IoT can effectively overcome the shortcomings of terrestrial IoT systems, and space-based IoT transmission technology has been the subject of extensive attention and research. In space-based IoT systems, the coverage area of ​​a satellite is typically several thousand kilometers, and the number of space-based IoT user terminals to be served is enormous, which imposes high demands on simultaneous multi-user transmission capacity and necessitates the design of an efficient multi-user transmission system. Contents of the invention

[0004] The embodiment of the present invention provides a method and a device for multi-user spatial IoT transmission based on LFM, to reduce transmission power demand, achieve low energy consumption, and offer a simultaneous multi-user scheme and achieve simultaneous multi-user access and transmission with the same time-frequency resources.

[0005] Embodiments of the present invention provide a multi-user spatial IoT transmission method based on LFM, characterized in that it comprises:

[0006] perform the following steps at the transmission terminal:

[0007] configure corresponding slopes for LFM modulated time-frequency waveforms for different users in order to determine the modulated signal of any user, the slope configured for said any user satisfying a fractional multiplicative slope without changing the frequency spreading factor;

[0008] determine, on the basis of the relationship between phase and frequency, a time domain signal for the LFM modulated signal of any of said users, in order to carry out a transmission on the basis of the determined time domain signal;

[0009] perform the following steps at the receiving terminal:

[0010] determination of a time domain signal of the unmodulated and down-chirped LFM signal corresponding to any one of the users;

[0011] the processing of the time domain signal of any of said users on the basis of the time domain signal of said unmodulated and down-chirped LFM signal;

[0012] The signal obtained after signal processing is subjected to a discrete Fourier transform, which is used to demodulate the signal received from any of the users by searching for the maximum value.

[0013] Optionally, the corresponding slopes are configured for the LFM-modulated time-frequency waveforms of different users in order to determine whether the modulated signal of any user satisfies:

[0014] f(r,m)

[0015] where B is the wide + w(f-^)ur band, M = 2SF, = SF denotes the frequency spreading factor, and m E [0,1, ..., M - 1], ,and K, is the slope of the Unth user, and Kj E (0,2), and [ST - Kf\ > 0.05, i ï j, and u( t) is the step function.

[0016] Optionally, based on the phase-frequency relationship, it is determined that the time-domain signal of said LFM modulated signal of any one of the users satisfies:

[0017] = t2KrBtu ( ) ]

[0018] where a' ( f, m ) is the LFM modulated signal.

[0019]

[0020]

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[0034] Optionally, the time domain signal of said unmodulated and down-chirped LFM signal corresponding to any one of the users satisfies: x0 = x* ( ≤ 0 ) = e-^ [ w ] where x*(t', 0) denotes the conjugate of x(t.0) • Optionally, a time-domain signal based on said unmodulated and down-chirped LFM signal processes the time-domain signal of any user; this processing includes the following elements: by multiplying the time-domain signal based on said unmodulated and down-chirped LFM signal by this time-domain signal to eliminate the quadratic term of the time-domain signal, thereby satisfying: x ( i: m ) • x0 = ) 1 • Optionally, the signal obtained after signal processing is discretized to demodulate the signal received from any of the users, including: the discretized signal satisfies: x^ y-;m] • x0 = ] where t = 4, n is the numerical sequence number, and / is the time J? sampling; perform a Fourier transform on the discretized signal, and this satisfies: FF xi m -x0 rx-l . = L whose maximum value corresponds to k, which is the symbolic information of 1 user i: (Mm) j | • The embodiment examples of this application also present a multi-user spatial IoT transmission device based on LFM, characterized in that it comprises a processor and a memory, said memory storing computer programs, said computer programs, when executed by the processor, implementing the steps of the multi-user spatial IoT transmission method based on LFM as described above. The embodiment examples of this application also present a readable computer storage medium, characterized in that said readable computer storage medium records computer programs, said computer programs, when executed by the processor, implements the steps of the LFM-based multi-user spatial IoT transmission method as described above.

[0035] The present invention proposes a proper demodulation method based on LFM modulation technology, enabling a very low signal-to-noise ratio, reducing transmission power requirements, and achieving low energy consumption. Furthermore, this application proposes a simultaneous multi-user scheme to enable simultaneous access and transmission by multiple users within the same time-frequency resources, thus providing a technical basis for the design of low-power, heavy-duty IoT transmission systems for users.

[0036] The above description is only an overview of the technical solution of this application. In order to make the technical means of this application more clearly understood and to make them possible to implement them in accordance with the description, and in order to make the above and other objects, features and advantages of this application more clearly understood, specific embodiments of this application will be presented below. Illustrations

[0037] Upon reading the detailed descriptions of the preferred embodiments below, the other advantages and benefits will become clear to those skilled in the art. The accompanying drawings are used solely to illustrate the preferred embodiment and are not considered a limitation of this application. Furthermore, in all the accompanying drawings, the same symbols are used to indicate the same components. In the accompanying drawings:

[0038] [Fig.1] is a basic flowchart of a multi-user spatial IoT transmission method of an example embodiment of the present application;

[0039] [Fig.2] is a frequency curve of the signals corresponding to the same symbols for different users as a function of time in this example embodiment;

[0040] [Figures 3a, 3b and 3c] are the signal frequency curves as a function of time according to the different slopes in examples of embodiment of the present application;

[0041] [Fig. 4] shows the performance curve of multi-user demodulation with different slopes in the embodiment examples of this application. Specific implementation

[0042] Exemplary embodiments of this disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of this disclosure are illustrated in the accompanying drawings, it should be understood that this disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to facilitate a more comprehensive understanding. depth of this disclosure and to enable communication of the full scope of this disclosure to those in the art.

[0043] Embodiments of the present invention provide a multi-user spatial IoT transmission method based on LFM, as illustrated in [Fig. 1], comprising:

[0044] Perform the following steps at the transmission terminal:

[0045] In step S101, configure corresponding slopes for LFM-modulated time-frequency waveforms for different users in order to determine the modulated signal of any user, the slope configured for said user satisfying a fractional multiplicative slope without changing the frequency spreading factor. In this example, the fractional multiplicative slope can be the difference between the slopes assigned to the users within a certain small range. In a multi-user transmission scheme, the bandwidth is defined as B, and the frequency spreading factor is SF, then an LFM (linear frequency modulation) symbol consists of M - 2SF chips, of which M - 2SF is the number, then the duration of a symbol is ~■

[0046] Therefore, at the transmitter terminal, the instantaneous frequency of the LFM (upward chirp) modulated signal of the eleventh user satisfies:

[0047] f (t- m) tK;-B)

[0048] = + tK. _ Aim - )

[0049] where m E [0.1, , M - 1], ^,cst is the slope of the nth user, and Kj E (0,2) , \K. - Kj\ > 0.05, i F j and y ( t ) is the function to scale.

[0050] At step S102, determine, on the basis of the relationship between phase and frequency, a time domain signal for the LFM modulated signal of any of said users, in order to carry out a transmission on the basis of the determined time domain signal.

[0051] In certain embodiments, based on the phase-frequency relationship, it is determined that the time-domain signal of said LFM modulated signal of any one of the users satisfies:

[0052] y ( mj _ t~KrBt-u() ) ]

[0053] where x ( t'. m ) is the LFM modulated signal.

[0054] Perform the following steps at the receiving terminal:

[0055] At step S103, determination of a time domain signal of the unmodulated and down-chirped LFM signal corresponding to any one of the users.

[0056] In certain embodiments, the time-domain signal of said unmodulated and down-chirped LFM signal corresponding to any one of the users satisfied with:

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[0072] x0 = x* ( ≤ 0 ) = [ w ] where x*( r, 0) denotes the conjugate of x(≤ 0) • At step S104, the processing of the time domain signal of any of said users on the basis of the time domain signal of said unmodulated and down-chirped LFM signal. In some examples, a time-domain signal based on said unmodulated and down-chirped LFM signal processes the time-domain signal of any user; this processing includes the following elements: by multiplying the time-domain signal based on said unmodulated and down-chirped LFM signal by this time-domain signal to eliminate the quadratic term of the time-domain signal, thereby satisfying: x(f, m) ■ Xq = )]. In some embodiments, the signal obtained after signal processing is discretized to demodulate the signal received from any one of the users; this including: the discretized signal satisfies: where f = y-, n is the numerical sequence number, and is the time sampling; Perform a Fourier transform on the discretized signal, and this satisfies: y-; mj • Xq = whose maximum value corresponds to k, which is the symbolic information of user i: (Mm) ]) • -b In step S105, the signal obtained after signal processing is subjected to a trans Discrete Fourier transform, which is used to demodulate the signal received from any of the users. Consequently, a different slope K is applied for each different user; this allows for the correct demodulation of the different users at the receiver and enables simultaneous transmission from multiple users. The method described herein also requires an example of the implementation of a multi-user LFM-based IoT transmission method in space, comprising the following steps:

[0073] Define the bandwidth: B — 512 kHz, the frequency spreading factor: SF = 13. When the number of users is 3, the implementation steps are as follows:

[0074] At the transmitter terminal level, in step S201, design the Kt of 3 users as 0.95, 1.0 and 1.05, respectively, and the different waveforms of LFM modulated signals can be obtained according to a different Kj,

[0075] The waveform of the time-domain signal of said LFM modulated signal of the nth user satisfies:

[0076] = ^[”4 ) ]

[0077] At the receiving terminal, at step S202, the continuous signal is discretized and the sampling time is / .

[0078] At step S203, by multiplying the time-domain signal based on said unmodulated and down-chirped LFM signal = / ; 0 ) = P31 this signal of user time domain, to eliminate the quadratic term from the time domain signal, satisfying:

[0079] x ( r, m ) - x0 = .

[0080] At the receiving terminal, in step S204, a discretized Fourier transform is performed at point 2SF, which satisfies:

[0081] rw7.r[ / „ \ 1 -, (b DkTx( f ;m) • x0j = ------wv------

[0082] whose corresponding maximum value corresponds to k, which is the information on the symbol of user i. The correct demodulation of the 3 user information with the same frequency spreading factor is achieved.

[0083] In this example embodiment, the simulation results of the multi-user LFM-based spatial IoT transmission scheme are presented in the accompanying figures. As shown in Figures 2 to 4, [Fig. 2] illustrates the signal frequency variation curve as a function of time for different users with different fractional slopes. Using the fractional slope selection criterion designed in this application, the different users can be modulated on the basis of the same frequency spreading factor. Figures 3a to 3c show the DFT spectrogram of the demodulated signal at different slopes, demonstrating that the multi-user spatial IoT transmission method using the present application no longer produces a single-frequency signal at different slopes, but that the maximum value is evident and can be correctly demodulated. [Fig.4] shows the multi-user demodulation performance curve at different slopes, showing that the performance of the multi-user spatial IOT transmission method of this demand for users at fractional slope. can achieve the same demodulation performance for a non-fractional slope.

[0084] Embodiments of the present invention propose a correct demodulation method based on LFM modulation technology that supports a very low signal-to-noise ratio, reducing the transmission power requirement and enabling low energy consumption. The LFM multi-user transmission method based on the differentiated fractional slope proposed in this application supports IoT user access and transmission at very low signal-to-noise ratios. The transmission method of this application supports simultaneous access and transmission by multiple users with the same time-frequency resources and can be flexibly combined with other multi-user schemes, which has the significant advantage of exponentially increasing the number of supported users.

[0085] Embodiments of the present application also feature a readable computer storage medium, characterized in that said readable computer storage medium stores computer programs, said computer programs, when executed by the processor, implement the steps of the LFM-based multi-user spatial IoT transmission method as described above.

[0086] The present invention proposes a proper demodulation method based on LFM modulation technology, enabling a very low signal-to-noise ratio, reducing transmission power requirements, and achieving low energy consumption. Furthermore, this application proposes a simultaneous multi-user scheme to enable simultaneous access and transmission by multiple users within the same time-frequency resources, thus providing a technical basis for the design of low-power, heavy-duty IoT transmission systems for users.

[0087] It is noted that in these embodiments, the terms "including", "comprising", or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a range of elements includes not only those elements, but also other elements not expressly listed, or which are inherent in such a process, method, article, or device. Without further limitation, the inclusion of an element as defined by the term "including a..." does not preclude the existence of another identical element in the process, method, article, or device that includes that element.

[0088] The trademarks of embodiments of this application are indicated for descriptive purposes only and do not represent the merits or disadvantages of the methods of implementation.

[0089] From the preceding description of the implementation, it is clear to those skilled in the art that the method described above can be implemented using software and the necessary common hardware platform, or of course using hardware, but in many cases, the former is preferable. Based on this understanding, the technical solution of the present application, or the part of the technical solution of the present application that essentially contributes to the prior art, can be implemented in the form of software products, which are stored on a storage medium (e.g., ROM / RAM, disk, CD-ROM) and comprise a number of instructions to enable a terminal (which may be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to perform the processes described in each of the embodiments.

[0090] The embodiments of the present application have been described above in relation to the attached drawings, but the present application is not limited to the specific embodiments above, which are merely illustrative and not limiting, and there are many other forms which could be made by a person of ordinary skill in the art, inspired by the present application, without departing from the scope protected by the subject matter and claims of the present application, all of which are under the protection of the present application.

Claims

Demands

1. A multi-user spatial IoT transmission method based on LFM, characterized in that it comprises: performing the following steps at the transmit terminal: configuring corresponding slopes for LFM-modulated time-frequency waveforms for the different users in order to determine the modulated signal of any user, wherein the slope configured for said any user satisfies a fractional multiplicative slope without changing the frequency spreading factor; determining, on the basis of the phase-frequency relationship, a time-domain signal for the LFM-modulated signal of any of said users, in order to perform a transmission on the basis of the determined time-domain signal;The following steps are performed at the receiving terminal: determination of a time domain signal from the unmodulated and down-chirped LFM signal corresponding to any one of the users; processing of the time domain signal from any of said users on the basis of the time domain signal from said unmodulated and down-chirped LFM signal; the signal obtained after signal processing is subjected to a discrete Fourier transform, which is used to demodulate the received signal from any one of the users by searching for the maximum value.

2. Multi-user spatial IoT transmission method based on LFM according to claim 1, characterized in that the corresponding slopes are configured for the LFM-modulated time-frequency waveforms of different users in order to determine whether the modulated signal of any user satisfies: f(r,m) = m-^ + ^-tKrB- ) J \ ? / M i ç i \ d / where B is the bandwidth, M — 2SF, Tç = ^' SF denotes the frequency spreading factor, and m G [0,1, .... M - 1], and Ki is the slope of the i-th user, and K; G (0,2), and >0.05, ij, and u( t) is the step function.

3. Multi-user spatial IoT transmission method based on the LFM according to claim 2, characterized in that, on the basis of the relationship between phase and frequency, it is determined that the time domain signal of said LFM modulated signal of any one of the users satisfies: x ( t, m ) = eJ2jT [t+^ f2KrBtu () ] where x(f, m) is the LFM modulated signal.

4. Multi-user spatial IoT transmission method based on LFM according to claim 3, characterized in that the time domain signal of said unmodulated and down-chirped LFM signal corresponding to any one of the users satisfies: x0 = x* ( f, 0 ) = where x * ( F 0 ) denotes the conjugate of x ( F, 0 ) •

5. A multi-user spatial IoT transmission method based on LFM according to claim 4, characterized in that a time-domain signal based on said unmodulated and down-chirped LFM signal processes the time-domain signal of any user, this processing comprising the following elements: by multiplying the time-domain signal based on said unmodulated and down-chirped LFM signal by this time-domain signal to eliminate the quadratic term of the time-domain signal, this satisfying: x ( F, m ) ■ x0 = ^8^1 ( ) 1 •

6. A multi-user spatial IoT transmission method based on LFM according to claim 5, characterized in that the signal obtained after signal processing is discretized to demodulate the signal received from any one of the users, this comprising: the discretized signal satisfies: x^y - (mj - x0) = ] where t - f, n is the digital sequence number, and fs is the sampling time; performing a Fourier transform on the discretized signal, and this satisfies: FT[x(f;m) • x0] - l / n \ F(Mm) 1 1 -LU ® whose maximum value corresponds to k, which is the symbolic information of user i: ]) • A

7. TTM LFM-based multi-user spatial IoT transmission device, characterized in that it comprises a processor and memory, said memory storing computer programs, said computer programs, when executed by the processor, implementing the steps of the LFM-based multi-user spatial IoT transmission method as described in any one of claims 1

8. a o. Readable computer storage medium, characterized in that said readable computer storage medium recording computer programs, said computer programs, when executed by the processor, implements the steps of LFM-based multi-user spatial IoT transmission method as described in any one of claims 1 to 6.