Access capacity test method suitable for multi-target satellite measurement and control communication system

Abstract

The invention relates to the field of spaceflight measurement and control, and provides an access capacity test method suitable for a multi-target satellite measurement and control communication system, which comprises the following steps of: constructing spectrum characteristics of different satellites through a digital domain by utilizing a set of multi-target simulation equipment, constructing different satellite identifiers by automatically generating data frames, and simulating hundreds of satellites to send access application frames; and the purpose of efficiently and conveniently testing the access capacity index is achieved. According to the invention, the cost and time of the access capacity index test are greatly reduced, and the test method is economical and efficient.

Description

Technical Field

[0001] The present invention relates to a method for testing access capacity in the field of aerospace TT&C, and is particularly applicable to a method for testing the access capacity of a multi-target satellite TT&C communication system. Background Art

[0002] With the explosive growth of the number of satellites, how to conduct efficient TT&C communication for a large number of satellites has become an important issue. To solve this problem, drawing on the ideas of terrestrial mobile communication, some scholars have proposed multi-target TT&C communication technology for satellites, which is one of the current research hotspots.

[0003] The access capacity refers to the maximum number of satellite access requests that can be responded to per unit time. The access capacity index is used to evaluate the upper limit of the number of TT&C communication satellite targets and is an important index for measuring the system's capabilities. Since the increase in the number of satellite targets is a gradual process, there is currently no effective test method for access capacity, and a reasonable and feasible test and evaluation method needs to be designed.

[0004] In a terrestrial mobile communication system, a typical method for testing system capacity is as follows: Determine the traffic model based on the theoretical capacity of the communication system, set the number of call attempts, the holding time of each call, and the interval time, and evaluate the system capacity value based on the test results. Different from the terrestrial mobile communication system, a multi-target satellite TT&C communication system can simultaneously process multiple target signals with different spectral characteristics and parallelly identify different satellite identity identifiers (IDs). Therefore, the test method of mobile communication cannot be directly applied, and the characteristics of the system's parallel processing need to be considered. Summary of the Invention

[0005] In order to solve the problems in the background art, a method for testing the access capacity of a multi-target satellite TT&C communication system is proposed. By using a set of multi-target simulation devices, the spectral characteristics of different satellites are constructed in the digital domain, different satellite IDs are constructed by automatically generating data frames, and hundreds of satellites are simulated to send access request frames in parallel for a short time, achieving the purpose of efficient, convenient, and low-cost testing of the access capacity index.

[0006] The technical solution of the present invention is as follows:

[0007] A method for testing the access capacity of a multi-target satellite TT&C communication system, comprising the following steps:

[0008] (1) Through cyclic counting, generate multiple different satellite IDs each time counting, and generate corresponding data frames;

[0009] (2) Parallelly perform spread-spectrum code modulation, Doppler frequency offset, and amplitude adjustment on multiple data frames, then merge them into one signal, and up-convert it to a radio frequency signal;

[0010] (3) Set the time interval between the previous and the next loop counts and the total transmission time, such that the data transmission volume is not less than the product of the access capacity and the test time, and transmit the radio frequency signal according to the set time;

[0011] (4) The receiving device captures and demodulates a plurality of signals from the received single-channel signal according to the spectrum characteristics, parses the satellite ID in the data frame, and automatically generates different response data packets according to different satellite IDs;

[0012] (5) Count the number of response data packets within the test time to obtain the test result of the access capacity index.

[0013] Further, in step (1), the satellite IDs of the N-channel signals transmitted at the initial moment are 1 to N in sequence, and thereafter the satellite IDs are cyclically and cumulatively incremented by N according to the number of channels.

[0014] Further, in step (2), adjust the symbol start phase, Doppler frequency offset, and amplitude of the spreading code to the ranges that can be correctly recognized by the receiver respectively; wherein, the ratio of the maximum signal energy of the amplitude to the sum of the energies of other channels is not greater than the total carrier-to-interference ratio requirement, and the symbol start phase and Doppler frequency offset are greater than the target resolution requirement.

[0015] Further, in step (3), the total number of transmissions is:

[0016] M = floor{NT / (T f + T d )} > CT

[0017] In the formula, M represents the total number of transmissions, floor{·} represents rounding down, C represents the access capacity index requirement, T represents the test time, T f represents the duration of each frame, and T d represents the time interval between two consecutive frames.

[0018] Further, the test result of the access capacity index in step (5) is:

[0019]

[0020] In the formula, is the number of response data packets actually tested and statistically obtained within the time T, is the access capacity calculated according to and the test time;

[0021] When holds, it is determined that the test is qualified.

[0022] The present invention has the following advantages compared with the background technology:

[0023] (i) The present invention constructs the spectral characteristics of different satellites in the digital domain, which is conducive to testing the multi-objective processing ability of the system access capacity.

[0024] (ii) The present invention constructs different satellite identity identifiers by automatically generating data frames, which is conducive to counting the number of data packets for responding to satellite access requests.

[0025] (iii) The present invention simulates hundreds of satellites sending access requests in a short time, which is conducive to the rapid and convenient test of the access capacity index, and greatly reduces the test complexity and cost. Description of the Drawings

[0026] Figure 1 It is the processing flow chart of the present invention.

[0027] Figure 2 It is the schematic diagram of generating satellite IDs by loop counting in the present invention. Detailed Embodiment

[0028] The following is a further description of the present invention in combination with specific implementation steps:

[0029] An access capacity test method suitable for a multi-objective satellite TT&C communication system, referring to Figure 1 , the specific steps include:

[0030] (1) Through loop counting, each time of counting generates multiple different satellite IDs and generates corresponding data frames;

[0031] As Figure 2 shown, at the initial moment, the satellite IDs sent by N channels of signals are 1 to N in sequence. After that, the ID accumulates and adds N in a loop according to the number of channels. The expression of the satellite ID (k, n) of the nth branch sent at the kth (k = 1,..., M) time is:

[0032]

[0033] In the formula, M is the total number of transmissions, and the maximum value of N is limited by the maximum parallel acquisition ability of the receiving device.

[0034] (2) Modulate the N data frames in parallel with spreading codes, Doppler frequency offset and amplitude adjustment, then merge them into one channel of signal and up-convert it into a radio frequency signal;

[0035] Among them, the sum of N channels of digital signals, and the normalized expression is:

[0036]

[0037] In the formula, t represents the time, n represents the nth (n = 1,..., N) digital branch, d n (t) represents data, An represents the amplitude, c(t) represents the spread - spectrum code modulation (the spread - spectrum codes of all targets are the same), T cn represents the starting time of the spread - spectrum code element, f dn represents the Doppler frequency offset, θ n represents the initial phase of the carrier wave.

[0038] During parallel processing, the starting phase of the spread - spectrum code element, the Doppler frequency offset, and the amplitude are respectively adjusted to the range that can be correctly recognized by the receiver; among them, the ratio of the maximum signal energy of the amplitude to the sum of the energies of other paths of signals is not greater than the total interference - to - signal - ratio requirement, that is:

[0039]

[0040] In the formula, without loss of generality, represents the maximum signal energy of the amplitude, represents the sum of the energies of other paths of signals, and ISR represents the total interference - to - signal - ratio requirement;

[0041] and the starting phase of the code element and the Doppler frequency offset are greater than the target resolution requirement.

[0042] (3) Set the time interval between the previous and next loop counts and the total transmission time, so that the data transmission volume is not less than the product of the access capacity and the test time, and transmit the radio - frequency signal according to the set time;

[0043] The total number of transmissions M can be calculated by the formula:

[0044] M = floor{NT / (T f +T d )}>CT

[0045] In the formula, M represents the total number of transmissions, floor{·} represents rounding down, C represents the access capacity index requirement, T represents the test time, T f represents the duration of each frame, T d represents the time interval between two consecutive frames.

[0046] (4) The receiving device demodulates the received single - path signal into multiple - path signals according to the spectral characteristics, resolves the satellite ID in the data frame, and automatically generates different response data packets according to different satellite IDs.

[0047] (5) Count the number of response data packets within the test time to obtain the test result of the access capacity index; among them, the test result of the access capacity index is:

[0048]

[0049] In the formula, is the number of response data packets actually tested and statistically obtained within the time T, is the access capacity calculated according to and the test time;

[0050] When it is determined that the test is qualified.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. An access capacity test method adapted to a multi-target satellite TT&C communication system, characterized in that It includes the following steps: (1) Through loop counting, generate multiple different satellite IDs each time counting, and generate corresponding data frames; (2) Modulate the spreading code, Doppler frequency shift, and amplitude adjustment for multiple data frames in parallel, then merge them into one signal and up-convert it to a radio frequency signal; (3) Set the time interval between the previous and next loop counting and the total transmission time, so that the data transmission volume is not less than the product of the access capacity and the test time, and send the radio frequency signal according to the set time; (4) The receiving device demodulates the received one signal into multiple signals according to the spectrum characteristics, parses out the satellite IDs in the data frames, and automatically generates different response data packets according to different satellite IDs; (5) Count the number of response data packets within the test time to obtain the test result of the access capacity index.

2. The access capacity test method for a multi-target satellite TT&C communication system according to claim 1, wherein In step (1), the satellite IDs sent by N signals at the initial moment are 1 to N in sequence, and thereafter the satellite IDs are cyclically accumulated by N according to the number of signals.

3. The access capacity test method for a multi-target satellite TT&C communication system according to claim 1, characterized in that In step (2), adjust the starting phase of the spreading code element, Doppler frequency shift, and amplitude to the ranges that can be correctly recognized by the receiver; among them, the ratio of the maximum signal energy of the amplitude to the sum of the energies of other signals is not greater than the total carrier-to-interference ratio requirement, and the starting phase of the code element and the Doppler frequency shift are greater than the target resolution requirement.

4. The access capacity test method for a multi-target satellite TT&C communication system according to claim 1, characterized in that In step (3), the total number of transmissions is: M = floor{NT / (T f + T d )} > CT Wherein, M represents the total number of transmissions, floor{·} represents rounding down, C represents the access capacity index requirement, T represents the test time, T f represents the duration of each frame, and T d represents the time interval between two consecutive frames.

5. The access capacity test method for a multi-target satellite TT&C communication system according to claim 3, characterized in that The test result of the access capacity index in step (5) is: In the formula, is the number of response data packets obtained through actual test statistics within time T, is the access capacity calculated according to and the test time; When it is determined that the test is qualified.

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