A preamble design system and method for simultaneous satellite access by massive mobile phone users

Abstract

The present invention proposes a preamble design system and method for the synchronous access of a large number of mobile phone users to a satellite. The computer of the present invention calculates the time-frequency resource format of the preamble according to the input scenario parameters and the target network type in combination with the minimum communication beam angle of the mobile phone, the equivalent cell diameter, and the satellite altitude; calculates the normalized carrier frequency offset of the mobile phone user in combination with the mobile phone's moving speed, carrier frequency, the angle of the mobile phone's moving direction, and the angle of the mobile phone's incident wave direction, and sets the subcarrier frequency interval; generates an initial ZC sequence; constructs a preamble sequence by cascading short sequences of the initial ZC sequence; and performs differentiated sequence amplitude allocation on the preamble sequence in combination with autocorrelation peak and pseudo-peak data. The present invention significantly reduces interference between users and improves the accuracy of preamble detection, thereby greatly improving the success rate of mobile phone users accessing the satellite.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite communications, and in particular relates to a preamble design system and method for synchronously accessing satellites by massive mobile phone users. Background Art

[0002] In the scenario of direct mobile phone connection to satellite communication, the mobile phone not only needs to access multiple heterogeneous networks on the ground, but also needs to be able to access satellite communication networks [1]. The core of this technology is to enable mobile phones to switch between satellite and terrestrial communication networks on demand, that is, to achieve heterogeneous network integration. However, due to the large number of mobile phone users, a large number of users will switch to the same satellite at the same time during the vertical handover process, resulting in serious interference between users [2]. In addition, the rapid movement of the satellite relative to the mobile phone will cause a significant Doppler effect, resulting in a large carrier frequency offset (CFO), which will affect the accuracy of the preamble detection and ultimately lead to random access failure and vertical handover failure [3].

[0003] In recent years, with the continuous development of satellite communication technology, the problem of realizing heterogeneous network integration in satellite and terrestrial communication networks for a large number of users has been raised.

[0004] Some solutions have emerged to this problem. For example, Chen Dong et al. proposed a mobile communication satellite network architecture based on GSO satellites and LEO satellite constellations [4]. Its advantage is that it can reduce certain interference, but it still has shortcomings in dealing with scenarios with a large number of users and the influence of the Doppler effect.

[0005] [1] Sun Yaohua, Peng Mugen. Low-orbit satellite communication for mobile phone direct connection: key technologies, development status and future prospects [J]. Telecommunications Science, 2023, 39(2): 25-36.

[0006] [2] Song Yanjun, Xiao Yongwei, Sun Chenhua. Analysis and development prospects of key technologies for direct mobile phone connection to satellite[J]. Telecommunication Science, 40(4):1-9.

[0007] [3] Sun Chuan, Mei Shunliang. Pre-correction of Doppler frequency deviation in satellite communications[J]. Journal of Radio Science, 2006, 21(2): 224-228.

[0008] [4] Chen Dong, Zhang Qian, Qin Zhaotao, et al. Satellite mobile communication system architecture and characteristics for mobile phone direct connection [J]. Integrated Space and Earth Information Network, 2023, 4(4): 11-18. Summary of the Invention

[0009] In order to solve the impact of inter-user interference and Doppler effect on the preamble detection process in the scenario of direct mobile phone connection to satellite communication and improve the success rate of random access and vertical switching, the present invention proposes a preamble design system and method for simultaneous access of massive mobile phone users to satellites.

[0010] The technical solution adopted by the method of the present invention is a preamble design system for synchronous satellite access by massive mobile phone users, comprising:

[0011] An oscilloscope, a computer, and a mobile phone user terminal; the mobile phone user terminal is wirelessly connected to the computer; the oscilloscope is wiredly connected to the computer;

[0012] The minimum communication belief angle, mobile phone moving speed, carrier frequency, angle of mobile phone moving direction, and angle of mobile phone incident wave direction are collected through the mobile phone user terminal, and the equivalent cell diameter and satellite altitude are collected through the satellite sensor of the mobile phone user terminal. The minimum communication belief angle, mobile phone moving speed, carrier frequency, angle of mobile phone moving direction, angle of mobile phone incident wave direction, equivalent cell diameter, and satellite altitude are wirelessly transmitted to a computer; the autocorrelation peak value and pseudo-peak value of the signal are collected by an oscilloscope and transmitted to the computer, and the computer reads the autocorrelation peak value and pseudo-peak value data of the signal collected by the oscilloscope through NI LabVIEW software; the computer calculates the time-frequency resource format of the leading edge according to the input scenario parameters and the target network type; calculates the normalized carrier frequency offset ξ of the mobile phone user and sets the subcarrier frequency interval SCS; generates an initial ZC sequence; constructs a leading sequence by short sequence cascading for the initial ZC sequence; and performs differentiated sequence amplitude allocation on the leading sequence obtained in step 4.

[0013] The technical solution adopted by the method of the present invention is a preamble design method for synchronously accessing a satellite by a large number of mobile phone users, comprising the following steps:

[0014] Step 1: The computer calculates the time-frequency resource format of the preamble based on the input scenario parameters and target network type, combining the minimum communication belief angle of the mobile phone, the equivalent cell diameter, and the satellite altitude;

[0015] Step 2: Calculate the normalized carrier frequency offset of the mobile phone user based on the mobile phone's speed, carrier frequency, the angle of the mobile phone's movement direction, and the angle of the mobile phone's incident wave direction, and set the subcarrier frequency interval;

[0016] Step 3: Generate the initial ZC sequence;

[0017] Step 4: Construct the leading sequence by concatenating the initial ZC sequence into short sequences;

[0018] Step 5: Perform differential sequence amplitude allocation on the leading sequence by combining the autocorrelation peak and pseudo-peak data;

[0019] As an example, the time-frequency resource format of the leading element in step 1 is composed of the duration T corresponding to the cyclic prefix CP, the leading sequence SEQ and the guard interval GT. CP, T SEQ , T GT .

[0020] The duration of the cyclic prefix CP is T CP Should meet the following requirements:

[0021] T CP ≥ΔRTD max +τ max

[0022] Where: τ max is the maximum delay spread, ΔRTD max is the maximum round-trip delay from mobile phone to satellite in the ground equivalent cell, and the calculation formula is:

[0023]

[0024] Among them, d max Indicates the maximum distance from the mobile phone to the satellite, d min represents the minimum distance between the mobile phone and the satellite, c represents the speed of light, d max and d min pass:

[0025]

[0026] Solve, where R is the radius of the earth, d is the equivalent cell diameter, H is the satellite height, and γ is the minimum communication angle of the mobile phone;

[0027] The duration T of the preamble sequence SEQ SEQ , the specific calculation is as follows

[0028]

[0029] Where N0 is the noise power spectral density, N f Expressed as noise figure, E P / N0 represents the ratio of sequence energy to thermal noise, which is determined by the false alarm rate and missed detection rate, P RA (r) is the received power of the PRACH signal, estimated using the Okumura-Hata empirical model;

[0030] The duration T of the guard interval GT GT Should meet the following requirements:

[0031] T GT ≥RTD max

[0032] Among them, RTD max for d max represents the maximum distance between the mobile phone and the satellite, and c represents the speed of light;

[0033] Preferably, the normalized carrier frequency offset ξ in step 2 is:

[0034]

[0035] Where Δf RA is the subcarrier frequency spacing SCS of PRACH, f d is the Doppler shift.

[0036] The Doppler shift f d for:

[0037]

[0038] Among them, f d is the Doppler shift, v is the speed of the mobile phone, f is the carrier frequency, and θ is the angle between the direction of mobile phone movement and the direction of the incident wave;

[0039] Preferably, the subcarrier frequency spacing SCS described in step 2 should simultaneously meet the following requirements:

[0040]

[0041]

[0042] Where Δf RA is the subcarrier frequency spacing SCS of PRACH, is the maximum Doppler shift of mobile phone users, Δf u is the subcarrier frequency spacing of PRACH, N + is a set of positive integers;

[0043] Preferably, the initial ZC sequence described in step 3 is generated as follows:

[0044]

[0045] Among them, Z l is the number of ZC sequences, is the root number of sequence n, Indicates the nth and root number is ZC sequence;

[0046] Preferably, the short sequence concatenation method in step 4 is:

[0047] The root sequence number in each user's leading position is short sequence Position number b u Uniformly distributed in {1, 2, ..., Z l};

[0048] Preferably, the differential sequence amplitude allocation method described in step 5 is:

[0049] Improve the amplitude ratio k of different ZC sequences in the leading sequence:

[0050]

[0051] in, and are the two ZC sequence root numbers used by mobile phone user u,

[0052] for The sequence processed by the differential sequence amplitude distribution method;

[0053] for The sequence processed by the differential sequence amplitude distribution method;

[0054] Among them, u represents the user serial number, and n represents the serial number;

[0055] a and b are the subscripts of the root sequence number, which are used to distinguish different root sequence numbers and improve the autocorrelation peak value R=k in the preamble detection. 2 ;

[0056] Preferably, the method for increasing the amplitude ratio k of different ZC sequences in the preamble sequence is:

[0057] Root number ZC sequence and amplitude amplification factor A b The root number after multiplication is ZC sequence

[0058] Root number ZC sequence and amplitude amplification factor A a The root number after multiplication is ZC sequence

[0059]

[0060] Preferably, the adaptive adjustment function is defined as follows:

[0061]

[0062] in, A b After adaptive adjustment, the value A a The value after adaptive adjustment, P peak_now is the current autocorrelation peak, P false_nowis the current pseudo peak value, and α and γ are adjustment coefficients.

[0063] Preferably, the amplitude amplification factor A b and A a By adaptive adjustment function, according to the real-time detection of autocorrelation peak value P peak_now and pseudo peak P false_now Dynamically adjust until the autocorrelation peak ratio R reaches the expected termination condition, where The autocorrelation peak value P peak_now and pseudo peak P false_now The termination condition for the autocorrelation peak ratio to reach the expected value is:

[0064] ΔR=|R new -R old |<∈

[0065] or

[0066] N iter ≥T max

[0067] Among them, R new is the autocorrelation peak ratio after a new round of iteration, R old is the autocorrelation peak ratio before the next round of iteration, ∈ is the change rate threshold, N iter is the current number of iterations, T max The maximum number of iterations is set.

[0068] The adjustment coefficients are: α, γ;

[0069] The maximum number of iterations set is: T max , the change rate threshold is: ∈.

[0070] The present invention provides a preamble design method for a large number of mobile phone users to access a satellite simultaneously. By optimizing the time-frequency resource format of the preamble, normalizing the carrier frequency offset, constructing a short sequence cascade ZC sequence, and differential sequence amplitude allocation, the method significantly reduces interference between users and improves the accuracy of preamble detection, thereby greatly improving the success rate of mobile phone users accessing the satellite. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 : A flow chart of a method according to an embodiment of the present invention;

[0072] Figure 2 : Schematic diagram of the short sequence cascade ZC sequence according to an embodiment of the present invention. DETAILED DESCRIPTION

[0073] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0074] In specific implementation, the method proposed in the technical solution of the present invention can be automatically run by those skilled in the art using computer software technology. System devices that implement the method, such as computer-readable storage media that store the corresponding computer program of the technical solution of the present invention and computer equipment that runs the corresponding computer program, should also be within the scope of protection of the present invention.

[0075] The following combination Figure 1-2 The technical solution of the embodiment of the present invention is a preamble design system and method for simultaneous satellite access by massive mobile phone users.

[0076] This embodiment takes the case where multiple mobile phone users access a satellite at the same time as an example to further illustrate the present invention.

[0077] The system embodiment of the present invention is a preamble design system for simultaneous satellite access by massive mobile phone users, comprising:

[0078] An oscilloscope, a computer, and a mobile phone user terminal; the mobile phone user terminal is wirelessly connected to the computer; the oscilloscope is wiredly connected to the computer;

[0079] The minimum communication belief angle, mobile phone moving speed, carrier frequency, angle of mobile phone moving direction, and angle of mobile phone incident wave direction are collected through the mobile phone user terminal, and the equivalent cell diameter and satellite altitude are collected through the satellite sensor of the mobile phone user terminal. The minimum communication belief angle, mobile phone moving speed, carrier frequency, angle of mobile phone moving direction, angle of mobile phone incident wave direction, equivalent cell diameter, and satellite altitude are wirelessly transmitted to a computer; the autocorrelation peak value and pseudo-peak value of the signal are collected by an oscilloscope and transmitted to the computer, and the computer reads the autocorrelation peak value and pseudo-peak value data of the signal collected by the oscilloscope through NI LabVIEW software; the computer calculates the time-frequency resource format of the leading edge according to the input scenario parameters and the target network type; calculates the normalized carrier frequency offset ξ of the mobile phone user and sets the subcarrier frequency interval SCS; generates an initial ZC sequence; constructs a leading sequence by short sequence cascading for the initial ZC sequence; and performs differentiated sequence amplitude allocation on the leading sequence obtained in step 4.

[0080] The model of the oscilloscope is Tektronix MD03000Series

[0081] The model of the computer shown is: HP Z4 G4 Workstation

[0082] The model of the mobile user terminal is: Huawei Mate 50Pro

[0083] Please see Figure 1 The method embodiment of the present invention is a technical solution for a preamble design method for synchronously accessing a satellite by a large number of mobile phone users, comprising the following steps:

[0084] Step 1: The computer calculates the time-frequency resource format of the preamble based on the input scenario parameters and target network type, combining the minimum communication belief angle of the mobile phone, the equivalent cell diameter, and the satellite altitude;

[0085] The time-frequency resource format of the leading element in step 1 is composed of the duration T corresponding to the cyclic prefix CP, the leading sequence SEQ and the guard interval GT. CP , T SEQ , T GT .

[0086] The duration of the cyclic prefix CP is T CP Should meet the following requirements:

[0087] T CP ≥ΔRTD max +τ max

[0088] Where: τ max is the maximum delay spread, ΔRTD max is the maximum round-trip delay from mobile phone to satellite in the ground equivalent cell, and the calculation formula is:

[0089]

[0090] Among them, d max Indicates the maximum distance from the mobile phone to the satellite, d min represents the minimum distance between the mobile phone and the satellite, c represents the speed of light, d max and d min pass:

[0091]

[0092] Solve, where R = 6378.137 represents the radius of the earth, d represents the equivalent cell diameter, H represents the satellite altitude, and γ represents the minimum communication angle of the mobile phone;

[0093] The duration T of the preamble sequence SEQ SEQ , the specific calculation is as follows

[0094]

[0095] Among them, N0=-174 is the noise power spectrum density, N f =5 represents the noise factor, E P / N0 represents the ratio of sequence energy to thermal noise, which is determined by the false alarm rate and missed detection rate, P RA (r) is the received power of the PRACH signal, estimated using the Okumura-Hata empirical model;

[0096] The duration T of the guard interval GT GT Should meet the following requirements:

[0097] T GT ≥RTD max

[0098] Among them, RTD max for d max represents the maximum distance between the mobile phone and the satellite, and c represents the speed of light;

[0099] Step 2: Calculate the normalized carrier frequency offset of the mobile phone user based on the mobile phone's speed, carrier frequency, the angle of the mobile phone's movement direction, and the angle of the mobile phone's incident wave direction, and set the subcarrier frequency interval;

[0100] The normalized carrier frequency offset ξ described in step 2 is:

[0101]

[0102] Where Δf RA is the subcarrier frequency spacing SCS of PRACH, f d is the Doppler shift.

[0103] The Doppler shift f d for:

[0104]

[0105] Among them, f d is the Doppler shift, v is the speed of the mobile phone, f is the carrier frequency, and θ is the angle between the direction of mobile phone movement and the direction of the incident wave;

[0106] The subcarrier frequency spacing SCS described in step 2 should simultaneously meet the following requirements:

[0107]

[0108]

[0109] Where Δf RA is the subcarrier frequency spacing SCS of PRACH, is the maximum Doppler shift of mobile phone users, Δf u =7.5 is the subcarrier frequency spacing of PRACH, N + is a set of positive integers;

[0110] Step 3: Generate the initial ZC sequence;

[0111] The initial ZC sequence described in step 3 is generated as follows:

[0112]

[0113] Among them, Z l is the number of ZC sequences, is the root number of sequence n, Indicates the nth and root number is ZC sequence;

[0114] Step 4: Construct the leading sequence by concatenating the initial ZC sequence into short sequences, such as Figure 2 As shown;

[0115] The short sequence concatenation method in step 4 is:

[0116] The root sequence number in each user's leading position is short sequence Position number b u Uniformly distributed in {1, 2, ..., Z l};

[0117] Step 5: Perform differential sequence amplitude allocation on the leading sequence by combining the autocorrelation peak and pseudo-peak data;

[0118] The differential sequence amplitude allocation method described in step 5 is:

[0119] Improve the amplitude ratio k of different ZC sequences in the leading sequence:

[0120]

[0121] in, and are the two ZC sequence root numbers used by mobile phone user u,

[0122] for The sequence processed by the differential sequence amplitude distribution method;

[0123] for The sequence processed by the differential sequence amplitude distribution method;

[0124] Among them, u represents the user serial number, and n represents the serial number;

[0125] a and b are the subscripts of the root sequence number, which are used to distinguish different root sequence numbers and improve the autocorrelation peak value R=k in the preamble detection. 2 ;

[0126] The method for increasing the amplitude ratio k of different ZC sequences in the leading sequence is:

[0127] Root number ZC sequence and amplitude amplification factor A b The root number after multiplication is ZC sequence

[0128] Root number ZC sequence and amplitude amplification factor A a The root number after multiplication is ZC sequence

[0129]

[0130] The adaptive adjustment function is defined as follows:

[0131]

[0132] in, A b After adaptive adjustment, the value A a The value after adaptive adjustment, P peak_now is the current autocorrelation peak, P false_now is the current pseudo peak value, and α and γ are adjustment coefficients.

[0133] The amplitude amplification factor A b and A a By adaptive adjustment function, according to the real-time detection of autocorrelation peak value P peak_now and pseudo peak P false_now Dynamically adjust until the autocorrelation peak ratio R reaches the expected termination condition, where The autocorrelation peak value P peak_now and pseudo peak P false_now The termination condition for the autocorrelation peak ratio to reach the expected value is:

[0134] ΔR=|R new -R old |<∈

[0135] or

[0136] N iter ≥T max

[0137] Among them, Rnew is the autocorrelation peak ratio after a new round of iteration, R old is the autocorrelation peak ratio before the next round of iteration, ∈ is the change rate threshold, N iter is the current number of iterations, T max The maximum number of iterations is set.

[0138] The adjustment coefficients are: α=0.05, γ=0.05.

[0139] The maximum number of iterations set is: T max =1500, the change rate threshold is: ∈=0.01. The performance comparison experimental results of the present invention, the single ZC sequence preamble and the long ZC sequence based preamble design method are as follows:

[0140] Table 1: Performance comparison experimental results of the present invention and other methods

[0141]

[0142] The detailed analysis of each indicator is as follows:

[0143] Vertical handover success rate: refers to the success rate of a mobile phone switching between different networks. The vertical handover success rate of the present invention reaches 95%, which is 12% and 8% higher than that of a single ZC sequence preamble and a long ZC sequence-based preamble, respectively.

[0144] Interference suppression capability: refers to the system's ability to suppress inter-user interference in a high-density user environment. The interference suppression ratio of the present invention reaches 18dB, which is 8dB and 6dB higher than that of a single ZC sequence preamble and a long ZC sequence-based preamble, respectively.

[0145] Autocorrelation Peak Ratio: This refers to the ratio of the target signal's autocorrelation peak to the interference signal's peak during preamble detection. The proposed method achieves an autocorrelation peak ratio of 2.5, which is 67% and 39% higher than single ZC sequence preambles and long ZC sequence-based preambles, respectively.

[0146] Computational complexity: refers to the time and resources required by the system to perform relevant calculations. The computational complexity of the present invention is 90ms, which is 10% and 25% higher than that of a single ZC sequence preamble and a long ZC sequence-based preamble, respectively.

[0147] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0148] It should be understood that the above description of the preferred embodiment is relatively detailed and cannot be regarded as limiting the scope of protection of the patent of the present invention. Under the guidance of the present invention, ordinary technicians in this field can also make substitutions or modifications without departing from the scope of protection of the claims of the present invention, which all fall within the scope of protection of the present invention. The scope of protection requested by the present invention shall be based on the attached claims.

Claims

1. A preamble design system for simultaneous satellite access by massive mobile phone users, characterized in that: include: Oscilloscope, computer, mobile phone user terminal; The mobile phone user terminal is wirelessly connected to the computer; The oscilloscope is connected to the computer via wire; The minimum communication belief angle, mobile phone moving speed, carrier frequency, angle of mobile phone moving direction, and angle of mobile phone incident wave direction are collected through the mobile phone user terminal, and the equivalent cell diameter and satellite altitude are collected through the satellite sensor of the mobile phone user terminal. The minimum communication belief angle, mobile phone moving speed, carrier frequency, angle of mobile phone moving direction, angle of mobile phone incident wave direction, equivalent cell diameter, and satellite altitude are wirelessly transmitted to a computer; the autocorrelation peak value and pseudo-peak value of the signal are collected by an oscilloscope and transmitted to the computer, and the computer reads the autocorrelation peak value and pseudo-peak value data of the signal collected by the oscilloscope through NI LabVIEW software; the computer calculates the time-frequency resource format of the leading edge according to the input scenario parameters and the target network type; calculates the normalized carrier frequency offset ξ of the mobile phone user and sets the subcarrier frequency interval SCS; generates an initial ZC sequence; constructs a leading sequence by a short sequence cascade method for the initial ZC sequence; and performs differentiated sequence amplitude allocation on the leading sequence based on the autocorrelation peak value and pseudo-peak value data.

2. A method for designing a preamble for a large number of mobile phone users to access a satellite synchronously using the preamble design system for a large number of mobile phone users to access a satellite synchronously according to claim 1, characterized in that: The following steps are involved: Step 1: The computer calculates the time-frequency resource format of the preamble based on the input scenario parameters and target network type, combining the minimum communication belief angle of the mobile phone, the equivalent cell diameter, and the satellite altitude; Step 2: Calculate the normalized carrier frequency offset of the mobile phone user based on the mobile phone's speed, carrier frequency, the angle of the mobile phone's movement direction, and the angle of the mobile phone's incident wave direction, and set the subcarrier frequency interval; Step 3: Generate the initial ZC sequence; Step 4: Construct the leading sequence by concatenating the initial ZC sequence into short sequences; Step 5: Combine the autocorrelation peak and pseudo-peak data to perform differential sequence amplitude allocation on the leading sequence.

3. The method for designing a preamble for simultaneous satellite access by a large number of mobile phone users according to claim 2, characterized in that: The time-frequency resource format of the leading element in step 1 is composed of the durations corresponding to the cyclic prefix CP, the leading sequence SEQ and the guard interval GT. , , ; The duration of the cyclic prefix CP Should meet the following requirements: in: is the maximum delay spread, is the maximum round-trip delay from mobile phone to satellite in the ground equivalent cell, and the calculation formula is: in, Indicates the maximum distance from the mobile phone to the satellite. Indicates the minimum distance from the mobile phone to the satellite. represents the speed of light, and pass: = Solve, where represents the radius of the Earth, represents the equivalent cell diameter, represents the satellite altitude, Indicates the minimum communication belief angle of the mobile phone; The duration of the leading sequence SEQ , the specific calculation is as follows in, is the noise power spectral density, Expressed as the noise figure, It represents the ratio of sequence energy to thermal noise, which is determined by the false alarm rate and missed detection rate. is the received power of the PRACH signal, estimated using the Okumura-Hata empirical model; The duration of the guard interval GT Should meet the following requirements: in, for , Indicates the maximum distance from the mobile phone to the satellite. Represents the speed of light.

4. The method for designing a preamble for simultaneous satellite access by a large number of mobile phone users according to claim 3, characterized in that: Normalized carrier frequency offset as described in step 2 for: in, is the subcarrier frequency spacing SCS of PRACH, is the Doppler shift; The Doppler shift for: in, is the Doppler shift, is the mobile phone speed, is the carrier frequency, is the angle between the direction of mobile phone movement and the direction of incident wave.

5. The method for designing a preamble for simultaneous satellite access by a large number of mobile phone users according to claim 4, characterized in that: The subcarrier frequency spacing SCS described in step 2 should simultaneously meet the following requirements: in, is the subcarrier frequency spacing SCS of PRACH, The maximum Doppler shift for mobile phone users, is the subcarrier frequency spacing of PRACH, is a set of positive integers.

6. The method for designing a preamble for simultaneous satellite access by a large number of mobile phone users according to claim 5, characterized in that: The initial ZC sequence described in step 3 is generated as follows: in, The number of ZC sequences, is the root number of sequence n, Indicates the nth and root number is ZC sequence.

7. The preamble design method for simultaneous satellite access by massive mobile phone users according to claim 6, characterized in that: The short sequence concatenation method in step 4 is: The root sequence number in each user's leading position is short sequence Position number Evenly distributed .

8. The method for designing a preamble for simultaneous satellite access by a large number of mobile phone users according to claim 7, characterized in that: The differential sequence amplitude allocation method described in step 5 is: Improve the amplitude ratio of different ZC sequences in the leading sequence : in, and Mobile phone users The two ZC sequence root numbers used are: for The sequence processed by the differential sequence amplitude distribution method; for The sequence processed by the differential sequence amplitude distribution method; in, represents the user serial number, and n represents the serial number; and They are the subscripts of the root sequence numbers, which are used to distinguish different root sequence numbers and improve the autocorrelation peak in the leading detection. .

9. The preamble design method for simultaneous satellite access by massive mobile phone users according to claim 8, characterized in that: The amplitude ratio of different ZC sequences in the leading sequence is increased The method is: Root number ZC sequence and amplitude amplification factor The root number after multiplication is ZC sequence ; Root number ZC sequence and amplitude amplification factor The root number after multiplication is ZC sequence 。 10. The preamble design method for simultaneous satellite access by massive mobile phone users according to claim 9, characterized in that: The adaptive adjustment function is defined as follows: in, for After adaptive adjustment, the value for After adaptive adjustment, the value is the current autocorrelation peak, is the current pseudo peak value, and is the adjustment factor; The amplitude amplification factor and The adaptive adjustment function is based on the autocorrelation peak detected in real time. and pseudo peaks Dynamic adjustment until the autocorrelation peak ratio The expected termination condition is reached, where , where the autocorrelation peak and pseudo peaks of The termination condition for the autocorrelation peak ratio to reach the expected value is: or Among them, R new is the autocorrelation peak ratio after a new round of iteration, R old is the autocorrelation peak ratio before the next round of iteration, is the rate of change threshold, is the current number of iterations, The maximum number of iterations is set.

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