Construction method of sub-optimal hopping time sequence set of low collision zone

Abstract

The invention discloses a construction method of a low collision zone suboptimal time hopping sequence set, which relates to the technical field of communication, and comprises the following steps: S1, generating a time hopping sequence h for a position sequence s on a finite field F based on a time shift operator delta according to the definition of the time hopping sequence; s2, defining an inter-symbol correlation function f (h1, h2, tau) as a correlation function between the time hopping sequence h1 and the time hopping sequence h2; s3, randomly determining a finite field F, the sequence length T'of the time hopping sequence and a position sequence set S, and ensuring that the length M of the position sequence set S is greater than the sequence length T 'of the time hopping sequence; s4, analyzing the collision zone performance of the constructed ground hop time sequence set H; s5, position sequence cross-correlation definition and mapping establishment; s6, determining a position sequence set A'based on the position sequence set S; by generating the ground hop time sequence set with the low collision characteristic, the secondary collision area is reduced, and the implementation difficulty is reduced as much as possible.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and more specifically to a method for constructing a suboptimal time hopping sequence set in a low collision zone. Background Art

[0002] Time hopping sequences play a key role in time-hopping multiple access in time-division multiple access wireless communication systems. Their diversity provides time slot diversity to meet the needs of random access by users. The performance of the time hopping sequence set is crucial to the randomness of the actual time hopping pattern and is the focus of attention in time hopping multiple access communication systems.

[0003] The time hopping sequence set is usually determined by a given time hopping sequence modulus value, a finite field, and a time shift operator, where each time hopping sequence represents a relatively fixed time slot, and its diversity can provide time slot diversity. The definition of the collision zone is used to evaluate the performance of the time hopping sequence set, which is divided into a primary collision zone and a secondary collision zone. The primary collision zone is when there are more than half of the time hopping sequences in the zero time slot collision zone, and the secondary collision zone is when there are no more than half of the time hopping sequences in the zero time slot collision zone. It is required that the primary collision zone between each time hopping sequence in the time hopping sequence set is zero, and the smaller the 0-secondary collision zone, the better.

[0004] However, the condition that the main collision zone is zero is difficult to achieve, and the existing time-hopping sequence sets have many problems, such as being relatively complex, poor performance, difficult to implement, and too simple. Therefore, it is of great significance to design a time-hopping sequence set that is better and easier to implement. In view of this, we propose a construction method for a suboptimal time-hopping sequence set with a low collision zone. Summary of the invention

[0005] The purpose of the present invention is to provide a method for constructing a suboptimal time hopping sequence set with a low collision zone. The technical problem to be solved is to design a more optimal and easy-to-implement time hopping sequence set to reduce the sub-collision zone while minimizing the difficulty of implementation.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for constructing a suboptimal time hopping sequence set in a low collision zone, comprising the following steps:

[0007] S1: According to the definition of time-hopping sequence, a time-hopping sequence h is generated for the position sequence s on the finite field F based on the time shift operator Δ;

[0008] S2: define the inter-symbol correlation function f(h1,h2,τ) as the correlation function between the time-hopping sequence h1 and the time-hopping sequence h2;

[0009] Among them, the expression of the time-hopping sequence h1 is h1(t)=s1(t-τΔ), and the expression of the time-hopping sequence h2 is h2(t)=s2(t-τΔ);

[0010] S3: Randomly determine the finite field F, the sequence length T′ of the time hopping sequence, and the position sequence set S, and ensure that the length M of the position sequence set S is greater than the sequence length T′ of the time hopping sequence;

[0011] S4: analyzing the collision zone performance of the aforementioned constructed time-hopping sequence set H;

[0012] S5: Position sequence cross-correlation definition and mapping establishment;

[0013] S501: define the cross-correlation between any two position sequences s and t in the position sequence set S as γ(s, t), and calculate the maximum cross-correlation value of all position sequences s

[0014] S502: construct a mapping relationship between the position sequence set S and the time hopping sequence set H, and deduce that the sequence with the maximum value of the mutual correlation and the position sequence has max{γ(s,t)}≤max F(Υ)|t|≤Z, where (0≤s≤|s|≤T), and Z represents the limit value, thereby clarifying the finite length of the subsequence related to the position sequence s, t;

[0015] S503: Let the minimum value of the mutual correlation of the position sequence s satisfy min{γ(s,t)}≤minF(γ)|s|≤W, where W is the correlation peak area corresponding to the minimum value of the mutual correlation of s, and determine the low collision area parameter W' accordingly;

[0016] S504: judging and operating according to the W value;

[0017] If W ≥ 1, generate the position sequence set S′ from the position sequence set S according to the formula min{γ(s, t)}≤minF(γ)|s|≤W;

[0018] If W<1, modify the number of elements in the finite field F and re-execute step S3-9;

[0019] S6: Determine a position sequence set S′ based on the position sequence set S;

[0020] S7: construct the time hopping sequence set H′ through the position sequence set S′;

[0021] S8: Analyze and evaluate the relevant performance of the time hopping sequence set H′ within the low collision zone parameter W′;

[0022] S9: Design requirements verification;

[0023] Given a low collision interval [W', Z], there are a number of elements Nk in the position sequence set S', Nk is compared with a preset value N, if Nk ≥ N, it is determined that the design requirements are met, and the time hopping sequence set H' is output; otherwise, it is determined that the design requirements are not met, the number of elements in the finite field F is modified, and step S3-9 is re-executed;

[0024] The present invention generates a time-hopping sequence set with low collision characteristics through steps 1-9, defines the mutual correlation value limit between time-hopping sequence pairs, sets the parameters of the time-hopping sequence set, generates an initial optimal time-hopping sequence set, performs maximum mutual correlation value analysis, updates the finite field and the position sequence set, generates a suboptimal time-hopping sequence set again, and adjusts the number of elements in the finite field and the low collision zone interval as required, and finally obtains a suboptimal time-hopping sequence set that meets the requirements, so as to design a more optimal and easy-to-implement time-hopping sequence set, reduce the sub-collision zone, and minimize the difficulty of implementation.

[0025] Preferably, the step S1 further comprises the following steps:

[0026] S101: According to the definition of the time hopping sequence, determine a position sequence s on the finite field F as a basic sequence;

[0027] S102: Introduce the time shift operator Δ, and according to the formula h(t)=s(t-τΔ), where the range is limited (0≤t≤T-1), the period τ of the given position sequence s and the time shift operator Δ and the number of symbols T of each time hopping sequence are given to generate the time hopping sequence h.

[0028] Preferably, step S2 further includes the following steps:

[0029] S201: According to the formula Define the inter-symbol correlation function f(h1,h2,τ) of the time-hopping sequence h1 and the time-hopping sequence h2, where F(h1(t)) represents a step function from 0 to h1(t) on the finite field F, and F(h1(t)-τ) represents a step function from 0 to h1(t)-τ on the finite field F;

[0030] S202: When F(x) is a unit step function, f(h1,h2,τ) is determined to be a correlation value, and constraints are set to calculate the maximum correlation value Q=max{f(h1,h2,τ)}, and at the same time, it is clarified that Q reaches the maximum value in the support area [α,β-α] of the step function F(a) on the finite field F;

[0031] S203: judging the relationship between the time hopping sequences according to the value of f(h1,h2,τ), if f(h1,h2,τ)=0, judging that the time hopping sequence h1 and the time hopping sequence h2 are non-orthogonal time hopping sequences, and when f(h1,h2,τ) has a collision zone of 0 in the correlation zone, there is a non-zero autocorrelation value, and 0 indicates that the time shift operator Δ=0,1,…,T-1;

[0032] Preferably, the constraint condition in step S202 is expressed as: |f(h1,h2,τ)|≤Q, where 0≤t≤T-1.

[0033] Preferably, the step S4 further comprises the following steps:

[0034] S401: Select two time hopping sequences h1 and h2 from the time hopping sequence set H;

[0035] S402: Calculate the maximum cross-correlation value Q′ of the time-hopping sequences h1 and h2, that is, Determining the correlation peak

[0036] The value range.

[0037] Preferably, step S6 further includes the following steps:

[0038] S601: Calculate the correlation peak area based on the maximum and minimum values ​​of the cross-correlation In the formula, It means rounding x upwards;

[0039] S602: Set the minimum mutual correlation condition min{γ(s,t)}>0 of the position sequence in the correlation peak region W to generate a position sequence set S′.

[0040] Preferably, in step S7, constructing the time hopping sequence set H′ by using the position sequence set S′ is performed in the following manner:

[0041] Let the position sequence set S′={s′1,s′2,…,s′ M}, determine the time shift operator Δ, period τ and the number of symbols T of each time hopping sequence, for each position sequence s′ i ∈S′, according to the formula h(t)=s′ i (t-τΔ) constructs the corresponding time-hopping sequence h′ i , we get h′ i (t) = s′ i (t-τΔ), 0≤t≤T-1, all ground-hopping time sequences h′ i Composed of a set, we get the time hopping sequence set H′, that is, H′=

[0042] {h′1,h′2,…,h′ M}.

[0043] Preferably, the step S8 further includes the following steps:

[0044] S801: randomly select two time hopping sequences from the time hopping sequence set H′;

[0045] S802: Calculate the maximum cross-correlation value Q′ of the two time-hopping sequences, and obtain f(h′1,h′2,τ)≤Q′(0≤τ≤T);

[0046] S803: derive f(h′1,h′2,τ)≤2Q′(0≤τ≤T-1) according to the above formula, and determine whether the maximum cross-correlation value Q′ of the time hopping sequence set H′ in the low collision area meets the design requirements based on the derivation result.

[0047] Preferably, the derivation process of f(h'1,h'2,τ)≤2Q'(0≤τ≤T-1) in step S803 is:

[0048] From h(t)=s(t-τΔ), we can see that the correlation of the time-hopping sequence is essentially derived from the correlation of the position sequence. When the low collision zone condition is considered and min{γ(s,t)}≤minF(γ)|s|≤W is used, the correlation function f(h'1,h'2,τ) of the time-hopping sequence will be additionally affected.

[0049] For 0≤τ≤T-1, the time-hopping sequences h'1 and h'2 are restored to their corresponding position sequences s'1 and s'2. Due to the cross-correlation restriction of the position sequence in the low collision zone, when analyzing the cross-correlation of the time-hopping sequence, compared with the original time-hopping sequence correlation constraint f(h'1,h'2,τ)≤Q'(0≤τ≤T), after considering the low collision zone characteristics:

[0050] In the time shift range from 0 to T-1, the cross-correlation function f(h'1,h'2,τ) between time-hopping sequences will have its upper limit doubled due to the cross-correlation superposition effect in the low collision zone of the position sequence. Combined with the characteristics of the position sequence in the low collision zone, in the interval of 0≤τ≤T-1, the cross-correlation value f(h'1,h'2,τ) satisfies f(h'1,h'2,τ)≤2Q'.

[0051] Preferably, in step S803, it is determined whether the maximum cross-correlation value Q' of the time hopping sequence set H' in the low collision area meets the low collision area design requirements by conduct.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1. The present invention generates a time-hopping sequence set with low collision characteristics through steps 1-9, by defining the mutual correlation value limit between time-hopping sequence pairs, setting the parameters of the time-hopping sequence set, generating an initial optimal time-hopping sequence set, performing maximum mutual correlation value analysis, updating the finite field and the position sequence set, and generating a suboptimal time-hopping sequence set again, and adjusting the number of elements in the finite field and the low collision zone interval as required, and finally obtaining a suboptimal time-hopping sequence set that meets the requirements, so as to design a more optimal and easy-to-implement time-hopping sequence set, reduce the sub-collision zone, and minimize the difficulty of implementation.

[0054] 2. The present invention also constructs a time hopping sequence set in which the mutual correlation values ​​of any two time hopping sequences are within the collision interval. In an actual communication system, the time hopping sequence set can be accurately designed according to specific needs so that its performance within the collision interval meets the expectations, effectively avoiding excessive interference between signals and improving the stability and reliability of communication.

[0055] 3. The present invention can also modify the maximum cross-correlation value of the time hopping sequence in the low collision area by adjusting the number of elements in the finite field F, so that the performance of the time hopping sequence set can be dynamically adjusted according to the actual communication environment and system requirements. By increasing or decreasing the number of elements in the finite field, the number of elements in the time hopping sequence set can be flexibly adjusted, and the scale of the time hopping sequence set can be conveniently adjusted to adapt to communication needs in different scenarios and optimize communication quality. DETAILED DESCRIPTION

[0056] The present invention relates to a method for constructing a low collision zone suboptimal time hopping sequence set, comprising the following steps:

[0057] S1: According to the definition of time-hopping sequence, a time-hopping sequence h is generated for the position sequence s on the finite field F based on the time shift operator Δ;

[0058] S101: According to the definition of the time hopping sequence, determine a position sequence s on the finite field F as a basic sequence;

[0059] S102: Introduce a time shift operator Δ, and generate a time hopping sequence h according to the formula h(t)=s(t-τΔ), where the range is limited (0≤t≤T-1), the period τ of the given position sequence s and the time shift operator Δ and the number of symbols T of each time hopping sequence;

[0060] S2: define the inter-symbol correlation function f(h1,h2,τ) as the correlation function between the time-hopping sequence h1 and the time-hopping sequence h2;

[0061] S201: According to the formula Define the inter-symbol correlation function f(h1,h2,τ) of the time-hopping sequence h1 and the time-hopping sequence h2, where F(h1(t)) represents a step function from 0 to h1(t) on the finite field F, and F(h1(t)-τ) represents a step function from 0 to h1(t)-τ on the finite field F;

[0062] In the embodiment of the present invention, the expression of the time hopping sequence h1 is h1(t)=s1(t-τΔ), and the expression of the time hopping sequence h2 is h2(t)=s2(t-τΔ);

[0063] S202: When F(x) is a unit step function, f(h1,h2,τ) is determined to be a correlation value, and constraints are set to calculate the maximum correlation value Q=max{f(h1,h2,τ)}, and at the same time, it is clarified that Q reaches the maximum value in the support area [α,β-α] of the step function F(a) on the finite field F;

[0064] In the embodiment of the present invention, the constraint condition is expressed as: |f(h1,h2,τ)|≤Q, where 0≤t≤T-1;

[0065] S203: judging the relationship between the time hopping sequences according to the value of f(h1,h2,τ); if f(h1,h2,τ)=0, judging that the time hopping sequence h1 and the time hopping sequence h2 have a correlation peak and a non-zero autocorrelation value, that is, the two are non-orthogonal time hopping sequences;

[0066] In the embodiment of the present invention, when f(h1, h2, τ) has a collision zone of 0 in the correlation zone, there is a non-zero autocorrelation value, and 0 represents the time shift operator Δ=0, 1, ..., T-1;

[0067] S3: Randomly determine the finite field F, the sequence length T' of the time hopping sequence, and the position sequence set S;

[0068] Based on the above-determined parameters, a position sequence set S of the position sequence is calculated and generated, and at the same time, the length M of the position sequence set S is ensured to be greater than the sequence length T' of the time hopping sequence;

[0069] S4: analyzing the collision zone performance of the aforementioned constructed time-hopping sequence set H;

[0070] S401: Select two time hopping sequences h1 and h2 from the time hopping sequence set H;

[0071] S402: Calculate the maximum mutual correlation value Q' of the time hopping sequences h1 and h2, that is, Determine the value range where the correlation peak lies;

[0072] S5: Position sequence cross-correlation definition and mapping establishment;

[0073] S501: define the cross-correlation between any two position sequences s and t in the position sequence set S as γ(s, t), and calculate the maximum cross-correlation value of all position sequences s

[0074] S502: construct a mapping relationship between a position sequence set S and a time hopping sequence set H, and deduce that when the maximum value of the mutual correlation of the position sequence and the sequence related to the position sequence have max{γ(s,t)}≤max F(γ)|t|≤Z, where (0≤s≤|s|≤T), Z represents a limit value, thereby clarifying the finite length of the subsequence related to the position sequences s and t;

[0075] S503: Let the minimum value of the mutual correlation of the position sequence s satisfy min{γ(s,t)}≤minF(Υ)|s|≤W, where W is the correlation peak area corresponding to the minimum value of the mutual correlation of s, and determine the low collision area parameter W' accordingly;

[0076] S504: judging and operating according to the W value;

[0077] If W ≥ 1, generate the position sequence set S' from the position sequence set S according to the formula min{γ(s, t)}≤minF(Υ)|s|≤W;

[0078] If W<1, modify the number of elements in the finite field F and re-execute step S3-9;

[0079] By adjusting the number of elements in the finite field F, the maximum cross-correlation value of the time-hopping sequence in the low collision area can be modified, so that the performance of the time-hopping sequence set can be dynamically adjusted according to the actual communication environment and system requirements. By increasing or decreasing the number of elements in the finite field, the number of elements in the time-hopping sequence set can be flexibly adjusted, and the scale of the time-hopping sequence set can be conveniently adjusted to adapt to communication needs in different scenarios and optimize communication quality.

[0080] S6: Determine a position sequence set S' based on the position sequence set S;

[0081] According to step S5, the correlation peak area W is determined, and the minimum value of the mutual correlation of the position sequence in the correlation peak area W is set to have min{Υ(s,t)}>0, so as to generate a position sequence set S';

[0082] S601: Calculate the correlation peak area based on the maximum and minimum values ​​of the cross-correlation In the formula, It is expressed as rounding x upwards, the purpose is to ensure that W is a positive integer, which is consistent with its property as a parameter of the correlation peak area;

[0083] S602: Setting the minimum value condition of the mutual correlation of the position sequences in the correlation peak region W as min{γ(s,t)}>0, thereby generating a position sequence set S', where the maximum value of the mutual correlation of the position sequences in the position sequence set S' is less than minF(γ);

[0084] S7: construct the time hopping sequence set H' through the position sequence set S';

[0085] The construction is guided by the position sequence correlation constraint embodied by max{γ(s,t)}≤maxF(γ)|t|≤Z, as follows:

[0086] Let the position sequence set S' = {s'1, s'2, ..., s' M}, determine the time shift operator Δ, period τ and the number of symbols T of each time hopping sequence, for each position sequence s' i ∈S', according to the formula h(t)=s' i (t-τΔ) constructs the corresponding time-hopping sequence h' i , we get h' i (t) = s' i (t-τΔ), 0≤t≤T-1, all ground-hopping time sequences h' i The time-hopping sequence set H' is formed into a set, that is, H' = {h'1, h'2, ..., h' M};

[0087] S8: Analyze and evaluate the relevant performance of the time hopping sequence set H' within the low collision zone parameter W';

[0088] Calculate the maximum mutual correlation value Q' of any two time hopping sequences in the time hopping sequence set H', and determine whether the maximum mutual correlation value Q' of the time hopping sequence set H' in the low collision area meets the design requirements based on the derivation result;

[0089] S801: randomly select two time hopping sequences from the time hopping sequence set H';

[0090] S802: Calculate the maximum cross-correlation value Q' of the two time-hopping sequences, and obtain f(h'1,h'2,τ)≤Q'(0≤τ≤T);

[0091] S803: derive f(h'1,h'2,τ)≤2Q'(0≤τ≤T-1) according to the above formula, and determine whether the maximum cross-correlation value Q' of the time hopping sequence set H' in the low collision area meets the design requirements according to the derivation result;

[0092] By constructing a time hopping sequence set in which the mutual correlation values ​​of any two time hopping sequences are within the collision interval, in an actual communication system, the time hopping sequence set can be accurately designed according to specific needs so that its performance within the collision interval meets expectations, effectively avoiding excessive interference between signals and improving the stability and reliability of communication.

[0093] In the embodiment of the present invention, the derivation process of f(h'1,h'2,τ)≤2Q'(0≤τ≤T-1) is:

[0094] From h(t)=s(t-τΔ), we can see that the correlation of the time-hopping sequence is essentially derived from the correlation of the position sequence. When the low collision zone condition is considered and min{γ(s,t)}≤minF(γ)|s|≤W is used, the correlation function f(h'1,h'2,τ) of the time-hopping sequence will be additionally affected.

[0095] For 0≤τ≤T-1, the time-hopping sequences h'1 and h'2 are restored to their corresponding position sequences s'1 and s'2. Due to the cross-correlation restriction of the position sequence in the low collision zone, when analyzing the cross-correlation of the time-hopping sequence, compared with the original time-hopping sequence correlation constraint f(h'1,h'2,τ)≤Q'(0≤τ≤T), after considering the low collision zone characteristics:

[0096] In the time shift range from 0 to T-1, the cross-correlation function f(h'1,h'2,τ) between time-hopping sequences will have its upper limit doubled due to the cross-correlation superposition effect in the low collision zone of the position sequence, that is, the upper limit is Q' when the correlation of the time-hopping sequence is considered alone, but combined with the characteristics of the position sequence in the low collision zone, in the interval of 0≤τ≤T-1, the cross-correlation value f(h'1,h'2,τ) satisfies f(h'1,h'2,τ)≤2Q';

[0097] In the embodiment of the present invention, it is determined whether the maximum cross-correlation value Q' of the time hopping sequence set H' in the low collision area meets the low collision area design requirements by conduct;

[0098] S9: Design requirements verification;

[0099] Given a low collision interval [W', Z], there are a number of elements Nk in the position sequence set S', Nk is compared with a preset value N, if Nk ≥ N, it is determined that the design requirements are met, and the time hopping sequence set H' is output; otherwise, it is determined that the design requirements are not met, the number of elements in the finite field F is modified, and step S3-9 is re-executed;

[0100] A time-hopping sequence set with low collision characteristics is generated through steps 1-9, by defining the mutual correlation value limit between time-hopping sequence pairs, setting the parameters of the time-hopping sequence set, generating an initial optimal time-hopping sequence set, performing maximum mutual correlation value analysis, updating the finite field and the position sequence set, generating a suboptimal time-hopping sequence set again, and adjusting the number of elements in the finite field and the low collision zone interval as needed, and finally obtaining a suboptimal time-hopping sequence set that meets the requirements, so as to design a more optimal and easy-to-implement time-hopping sequence set, reduce the sub-collision zone, and minimize the difficulty of implementation.

[0101] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A method for constructing a suboptimal time hopping sequence set in a low collision zone, characterized in that: The following steps are involved: S1: According to the definition of time-hopping sequence, a time-hopping sequence h is generated for the position sequence s on the finite field F based on the time shift operator Δ; S2: define the inter-symbol correlation function f(h1, h2, τ) as the correlation function between the time-hopping sequence h1 and the time-hopping sequence h2; S3: Randomly determine the finite field F, the sequence length T′ of the time hopping sequence, and the position sequence set S, and ensure that the length M of the position sequence set S is greater than the sequence length T′ of the time hopping sequence; S4: analyzing the collision zone performance of the aforementioned constructed time-hopping sequence set H; S5: Position sequence cross-correlation definition and mapping establishment; S501: define the cross-correlation between any two position sequences s and t in the position sequence set S as γ(s, t), and calculate the maximum cross-correlation value of all position sequences s S502: construct a mapping relationship between the position sequence set S and the time hopping sequence set H, and deduce that the sequence with the maximum value of the mutual correlation and the position sequence has max{γ(s, t)}≤max F(γ)|t|≤Z, where (0≤s≤|s|≤T), and Z represents the limit value, thereby clarifying the finite length of the subsequence related to the position sequence s, t; S503: Let the minimum value of the cross-correlation of the position sequence s satisfy min{γ(s, t)}≤minF(γ)|s|≤W, where W is the correlation peak area corresponding to the minimum value of the cross-correlation of s, and determine the low collision area parameter W′ accordingly; S504: judging and operating according to the W value; If W ≥ 1, generate the position sequence set S′ from the position sequence set S according to the formula min{γ(s, t)}≤minF(γ)|s|≤W; If W<1, modify the number of elements in the finite field F and re-execute step S3-9; S6: Determine a position sequence set S′ based on the position sequence set S; S7: construct the time hopping sequence set H′ through the position sequence set S′; S8: Analyze and evaluate the relevant performance of the time hopping sequence set H′ within the low collision zone parameter W′; S9: Design requirements verification; Given a low collision interval [W', Z], there are a number of elements Nk in the position sequence set S'. Compare Nk with the preset value N. If Nk ≥ N, it is determined that the design requirements are met and the time-hopping sequence set H' is output; otherwise, it is determined that the design requirements are not met, the number of elements in the finite field F is modified, and step S3-9 is re-executed.

2. The method for constructing a low collision zone suboptimal time hopping sequence set according to claim 1, characterized in that: The step S1 also includes the following steps: S101: According to the definition of the time hopping sequence, determine a position sequence s on the finite field F as a basic sequence; S102: Introduce the time shift operator Δ, and according to the formula h(t)=s(t-τΔ), where the range is limited (0≤t≤T-1), the period τ of the given position sequence s and the time shift operator Δ and the number of symbols T of each time hopping sequence are given to generate the time hopping sequence h.

3. The method for constructing a low collision zone suboptimal time hopping sequence set according to claim 1, characterized in that: The step S2 further comprises the following steps: S201: According to the formula Define the inter-symbol correlation function f(h1, h2, τ) of the time-hopping sequence h1 and the time-hopping sequence h2, where F(h1(t)) represents a step function from 0 to h1(t) on the finite field F, and F(h1(t)-τ) represents a step function from 0 to h1(t)-τ on the finite field F; S202: When F(x) is a unit step function, f(h1, h2, τ) is determined to be a correlation value, and constraints are set to calculate the maximum correlation value Q=max{f(h1, h2, τ)}, and at the same time, it is clarified that Q reaches the maximum value in the support area [α, β-α] of the step function F(a) on the finite field F; S203: Determine the relationship between the time hopping sequences according to the value of f(h1, h2, τ). If f(h1, h2, τ) = 0, determine that the time hopping sequence h1 and the time hopping sequence h2 are non-orthogonal time hopping sequences.

4. The method for constructing a low collision zone suboptimal time hopping sequence set according to claim 3, characterized in that: The constraint condition in step S202 is expressed as: |f(h1, h2, τ)|≤Q(0≤t≤T-1).

5. The method for constructing a low collision zone suboptimal time hopping sequence set according to claim 1, characterized in that: The step S4 also includes the following steps: S401: Select two time hopping sequences h1 and h2 from the time hopping sequence set H; S402: Calculate the maximum cross-correlation value Q′ of the time-hopping sequences h1 and h2, that is, Determine the value range where the correlation peak lies.

6. The method for constructing a low collision zone suboptimal time hopping sequence set according to claim 1, characterized in that: The step S6 also includes the following steps: S601: Calculate the correlation peak area based on the maximum and minimum values ​​of the cross-correlation In the formula, It means rounding x upwards; S602: Set the minimum value condition of the mutual correlation of the position sequence in the correlation peak area W as min{γ(s, t)}>0, thereby generating a position sequence set S′.

7. The method for constructing a low collision zone suboptimal time hopping sequence set according to claim 1, characterized in that: The step S7 constructs the time hopping sequence set H′ by using the position sequence set S′ in the following manner: Suppose the position sequence set S′={s′1, s′2, …, s′ M }, determine the time shift operator Δ, period τ and the number of symbols T of each time hopping sequence, for each position sequence s′ i ∈S′, according to the formula h(t)=s′ i (t-τΔ) constructs the corresponding time-hopping sequence h′ i , we get h′ i (t) = s′ i (t-τΔ)(0≤t≤T-1), all ground-hopping time sequences h′ i The time hopping sequence set H′ is formed into a set, that is, H′={h′1, h′2, …, h′ M }.

8. The method for constructing a low collision zone suboptimal time hopping sequence set according to claim 1, characterized in that: The step S8 also includes the following steps: S801: randomly select two time hopping sequences from the time hopping sequence set H′; S802: Calculate the maximum cross-correlation value Q′ of the two time-hopping sequences, and obtain f(h′1, h′2, τ)≤Q′(0≤τ≤T); S803: derive f(h′1, h′2, τ)≤2Q′(0≤τ≤T-1) according to the above formula, and determine whether the maximum cross-correlation value Q′ of the time hopping sequence set H′ in the low collision area meets the design requirements based on the derivation result.

9. The method for constructing a low collision zone suboptimal time hopping sequence set according to claim 8, characterized in that: The derivation process of f(h′1, h′2, τ)≤2Q′(0≤τ≤T-1) in step S803 is: From h(t)=s(t-τΔ), we can see that the correlation of the time-hopping sequence is essentially derived from the correlation of the position sequence. When the low collision zone condition is considered and min{γ(s, t)}≤minF(γ)|s|≤W is used, the correlation function f(h′1, h′2, τ) of the time-hopping sequence will be additionally affected. For 0≤τ≤T-1, the time-hopping sequences h′1 and h′2 are restored to their corresponding position sequences s′1 and s′2. Due to the cross-correlation restriction of the position sequence in the low collision zone, when analyzing the cross-correlation of the time-hopping sequence, compared with the original time-hopping sequence correlation constraint f(h′1, h′2, τ)≤Q′(0≤τ≤T), after considering the low collision zone characteristics: In the time shift range from 0 to T-1, the cross-correlation function f(h′1, h′2, τ) between time-hopping sequences will have its upper limit doubled due to the cross-correlation superposition effect in the low collision zone of the position sequence. Combined with the characteristics of the position sequence in the low collision zone, in the interval of 0≤τ≤T-1, the cross-correlation value f(h′1, h′2, τ) satisfies f(h′1, h′2, τ)≤2Q′.

10. The method for constructing a low collision zone suboptimal time hopping sequence set according to claim 8, characterized in that: In step S803, it is determined whether the maximum cross-correlation value Q′ of the time hopping sequence set H′ in the low collision area meets the design requirements of the low collision area. conduct.

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