Anti-jamming and cross-network non-sensing scheduling method and system of VDES in multi-constellation superposition environment

Abstract

The application discloses a VDES anti-interference and cross-network non-sensing scheduling method and system in a multi-constellation superimposed environment, and belongs to the technical field of radio communication. The method comprises the following steps: a plurality of VDES heterogeneous low-orbit satellite constellations participating in cooperation are divided into two complementary subsets, and the frequency bands of transmission and reception are configured according to the mirror duplex rule, so that the downlink transmission frequency bands of the two subsets are completely staggered, and the interference of the opposite subsets is suppressed to the noise base by combining the shipborne terminal band-pass filter; on the basis of frequency domain orthogonality, an orthogonal spread spectrum sequence is introduced, a two-dimensional mapping matrix is constructed, and a unified roaming identifier and an independent network identifier are configured for each constellation. Through two-dimensional resource orthogonal division in the frequency domain and the code domain and a double-layer identifier system, the downlink same-frequency interference of the multi-constellation is fundamentally eliminated, and the non-sensing switching of the shipborne terminal between different constellations is realized.

Description

Technical Field

[0001] This invention relates to the field of radio communication technology, and in particular to a scheduling method and system for achieving frequency anti-interference and seamless roaming in an environment covered by multiple low-Earth orbit satellite constellations. This is achieved through mirror duplex frequency configuration, a bulletin board concurrency mechanism based on physical channels and spread spectrum sequence matrices, and a cross-network authentication and coordination mechanism based on a unified roaming identifier. Background Technology

[0002] As multiple commercial space companies accelerate the deployment of large-scale low-Earth orbit satellite constellations, different VDES satellite constellations inevitably operate in the exact same VHF maritime mobile frequency band. In the airspace covered by high-density superposition of multiple constellations (where signals from 3 to 4 satellite constellations may exist simultaneously in space), existing technologies face two critical issues.

[0003] (a) Catastrophic radio frequency interference and channel paralysis at the physical layer

[0004] Traditional satellite communication requires all constellations to use a unified frequency band configuration, meaning all satellites in the network statically use the same frequency band for transmission and reception. When multiple constellations overlap, the simultaneous high-power transmission of co-channel signals to the ground by satellites from multiple constellations can cause severe co-channel and adjacent-channel intermodulation interference. This leads to nonlinear blocking and saturation overload of the low-noise amplifier (LNA) at the front end of the shipborne receiver, causing the signal-to-noise ratio of the synthesized signal received by the receiver to approach zero or even become negative, resulting in the complete paralysis of the underlying physical transceiver link.

[0005] Meanwhile, the bulletin board serves as a network access guide and identification card for satellites that continuously broadcast signals. Shipborne terminals capture these signals to identify satellites, synchronize time, and obtain network parameters. When multiple constellations transmit bulletin board beacons in the same way on the same frequency band, the signals collide violently in a confined space, causing the shipborne terminals to completely lose their identification capabilities. They are unable to identify satellites, synchronize time, or obtain network parameters, failing even to cross the most basic network access threshold.

[0006] (ii) Frequent network and service interruptions and security risks

[0007] When shipborne terminals move between heterogeneous satellite networks built by different operators, traditional mechanisms require the terminals to undergo a complete process, including link disconnection and blind search across the entire frequency band, signaling parsing and identity discovery, cross-network handshake, and repeated authentication and registration. This process can take several seconds or even longer, severely disrupting time-sensitive services such as video conferencing and real-time weather data transmission. For special maritime life safety operations, the regulatory vacuum caused by constellation switching will prevent distress signals from being forwarded in a timely manner, directly threatening the lives of ships and crew. Summary of the Invention

[0008] To address the aforementioned issues, this application provides a VDES anti-interference and cross-network seamless scheduling method and system in a multi-constellation superposition environment. It aims to fundamentally eliminate downlink co-frequency interference between multiple constellations and achieve seamless switching of shipborne terminals between different constellations by orthogonally partitioning resources in the frequency domain and code domain and using a two-layer identification system.

[0009] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0010] In a first aspect, the present invention provides a method for VDES anti-interference and cross-network seamless scheduling in a multi-constellation superposition environment, which includes the following steps:

[0011] Step 1: Divide the N VDES heterogeneous low-Earth orbit satellite constellations participating in the collaboration into two complementary first constellation subsets A and second constellation subsets B, where 2≤N≤4;

[0012] Step 2: Configure a forward standard duplex link for the first constellation subset A: the uplink uses the first VHF band F. L The downlink uses the second VHF band F. H Configure a reverse mirrored full-duplex link for the second constellation subset B: the uplink uses the second VHF band F. H The downlink uses the first VHF band F L The first VHF band F L With the second VHF band F H They do not overlap in the frequency domain;

[0013] Step 3: Assign orthogonal spread spectrum sequences to each heterogeneous satellite constellation participating in the collaboration, so that the two-dimensional resource matrix composed of physical frequency bands and spread spectrum sequences assigned to each constellation does not overlap;

[0014] Step 4: Configure a unified roaming identifier and an independent network identifier for each heterogeneous satellite constellation participating in the collaboration.

[0015] As one embodiment of the present invention, the shipborne terminal uses a built-in logic state machine to continuously monitor the bulletin board beacons and signal quality of neighboring constellations while connecting to the current constellation. When it detects that the roaming identifier of a neighboring constellation is the same as that of the current constellation and that the signal quality is better than that of the current constellation, it performs a switch from the current constellation to the neighboring constellation.

[0016] As one embodiment of the present invention, the steps for determining the roaming identifier and signal quality before constellation switching by the shipborne terminal are as follows:

[0017] While connecting to the current constellation, the shipborne terminal uses the multi-path despreading parallel processing mechanism of baseband software-defined radio to demodulate and parse the satellite bulletin boards continuously broadcast by neighboring constellations in real time and extract the roaming identifier, which is then compared with the roaming identifier of the current constellation.

[0018] If the roaming identifier of an adjacent constellation is the same as that of the current constellation, and the difference between the signal level of the adjacent constellation and the signal level of the current constellation is not less than a preset threshold value. When the adjacent constellation is in a state of transition, it is determined that the adjacent constellation has entered the candidate state for switching.

[0019] Switching hysteresis is controlled by a sliding counter. When continuous The difference between the signal level of adjacent constellations and the signal level of the current constellation in each sampling period is not less than a preset threshold value. At that time, the final switch is triggered, in which, The value is a preset positive integer. If the difference in any sampling period is less than 100%, then the difference is considered to be less than 100%. If the counter is zeroed, then the counter will return to zero.

[0020] In one embodiment of the present invention, in step 4, the unified roaming identifier is configured to be universal across all heterogeneous satellite constellations participating in the collaboration, and the network identifier is configured to be independent for each constellation, used to identify the constellation to which the data payload belongs after the handover is completed.

[0021] In one embodiment of the present invention, the spreading sequence includes a first orthogonal spreading sequence SS0 and a second orthogonal spreading sequence SS1; the cross-correlation function of the first orthogonal spreading sequence SS0 and the second orthogonal spreading sequence SS1 is lower than a preset threshold under any time delay.

[0022] In one embodiment of the present invention, in step 3, the specific mapping relationship of the two-dimensional resource matrix is ​​as follows:

[0023] The downlink of the first constellation C1 in the first constellation subset A is allocated to the second VHF band F. H Combination with the first orthogonal spreading sequence SS0;

[0024] The downlink of the second constellation C3 in subset A of the first constellation is allocated to the second VHF band F. H Combination with the first orthogonal spreading sequence SS1;

[0025] The downlink of the third constellation C2 in subset B of the second constellation is allocated to the first VHF band F. L Combination with the second orthogonal spreading sequence SS0;

[0026] The downlink of the fourth constellation C4 in subset B of the second constellation is allocated to the first VHF band F. L Combination with the second orthogonal spread spectrum sequence SS1.

[0027] As one embodiment of the present invention, bandpass filters are configured for the shipborne terminal and the satellites in each heterogeneous satellite constellation participating in the collaboration. The bandpass filters are used to suppress interference signals in opposing frequency bands other than the target receiving frequency band.

[0028] As one embodiment of the present invention, the first VHF band F L The second VHF band F is a subset of the low-frequency band ranging from 157.300 MHz to 157.325 MHz. H It is a subset of the high-frequency band ranging from 161.900 MHz to 161.925 MHz.

[0029] Secondly, this application provides a VDES anti-interference and cross-network seamless scheduling system in a multi-constellation superposition environment, which includes:

[0030] The resource allocation module is used to divide the N participating VDES heterogeneous low-Earth orbit satellite constellations into a first constellation subset A and a second constellation subset B, and to configure a forward standard duplex link for the first constellation subset A: the uplink uses the first VHF band F. L The downlink uses the second VHF band F. H Configure a reverse mirrored full-duplex link for the second constellation subset B: the uplink uses the second VHF band F. H The downlink uses the first VHF band F L The first VHF band F L With the second VHF band F H In the frequency domain, they do not overlap, and orthogonal spreading sequences are allocated to each heterogeneous satellite constellation participating in the collaboration, forming a two-dimensional resource matrix composed of physical frequency bands and spreading sequences. The matrix resources occupied by each constellation do not overlap; where 2≤N≤4.

[0031] The two-dimensional matrix bulletin board broadcast module is set at the end of each satellite constellation and is used to broadcast bulletin board beacons according to the combination of physical frequency bands and spread spectrum sequences allocated to the constellation in the two-dimensional resource mapping matrix;

[0032] The SDR baseband demodulation module, located in the shipboard terminal, is used to perform frequency domain filtering and code domain despreading on the received bulletin board beacons via software-defined radio, so as to demodulate bulletin board beacons from different constellations respectively;

[0033] The dual-layer identification management module is used to configure a unified roaming identifier and an independent network identifier for each heterogeneous satellite constellation participating in the collaboration.

[0034] The terminal state machine switching module, located on the shipboard terminal, is used to continuously monitor the beacons of adjacent constellations. When it detects that the roaming identifier of an adjacent constellation is the same as that of the current constellation and that the signal quality is better than that of the current constellation, it triggers the shipboard terminal to perform a switch from the current constellation to the adjacent constellation.

[0035] As one embodiment of the present invention, the SDR baseband demodulation module includes a bandpass filter unit, a mixer unit, and a digital signal processor connected in sequence.

[0036] The out-of-band rejection ratio of the bandpass filter unit is not less than 60dB;

[0037] The digital signal processor has a built-in matched filter that stores templates of spread spectrum sequences for each constellation. This matched filter is used to perform code domain despreading and extract bulletin board broadcast information through correlation operations.

[0038] The beneficial effects of adopting the above technical solution are as follows:

[0039] The purpose of this invention is to provide a VDES anti-interference and cross-network collaborative scheduling method and system for multi-constellation superposition environments. It constructs a complete three-dimensional collaborative framework from the physical radio frequency layer to the network authentication layer, supporting up to four heterogeneous low-orbit satellite constellations to operate concurrently without collision or interference in the same airspace and frequency band. At the same time, it can realize seamless roaming switching of shipborne terminals through a two-layer identification system.

[0040] By constructing a two-dimensional resource matrix, the shipborne terminal can demodulate and distinguish beacon signals from multiple concurrent satellite constellations on a single hardware device without the need for additional physical radio frequency antennas or hardware demodulation links, relying solely on software-defined radio (SDR) baseband logic control. This significantly reduces the hardware complexity and cost of the shipborne terminal. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the two-dimensional concurrent demodulation process of the shipborne terminal on four constellation bulletin boards in a multi-constellation superposition environment according to the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the present invention clearer, the invention will be described clearly and completely below in conjunction with specific embodiments.

[0043] Example 1: Taking a four-constellation overlay scenario as an example

[0044] A method for VDES anti-interference and cross-network seamless scheduling in a multi-constellation superposition environment includes the following steps:

[0045] Step 1: Divide the four VDES heterogeneous low-Earth orbit satellite constellations participating in the collaboration into two complementary first constellation subset A and second constellation subset B;

[0046] That is: a collection of constellations ,and ;

[0047] Step 2: Configure a forward standard duplex link for the first constellation subset A: the uplink uses the first VHF band F. L The downlink uses the second VHF band F. H ;

[0048] Right now: ,in, For constellations The uplink, For constellations downlink;

[0049] Configure a reverse mirrored duplex link for subset B of the second constellation: the uplink uses the second VHF band F. H The downlink uses the first VHF band F L ;

[0050] Right now: ,in, For constellations The uplink, For constellations downlink;

[0051] The first VHF band F L With the second VHF band F H They do not overlap in the frequency domain;

[0052] Right now: ,and ,in, It is a dedicated satellite channel for the VDES system;

[0053] As a specific embodiment, the first VHF band F L The second VHF band F is a subset of the low-frequency band ranging from 157.300 MHz to 157.325 MHz. H This refers to a subset of the high-frequency band ranging from 161.900 MHz to 161.925 MHz.

[0054] Step 3: Assign orthogonal spread spectrum sequences to each heterogeneous satellite constellation participating in the collaboration, so that the two-dimensional resource matrix composed of physical frequency bands and spread spectrum sequences assigned to each constellation does not overlap;

[0055] Specifically, the spreading sequence includes a first orthogonal spreading sequence SS0 and a second orthogonal spreading sequence SS1; the cross-correlation function of the first orthogonal spreading sequence SS0 and the second orthogonal spreading sequence SS1 is lower than a preset threshold (e.g., 0.01) under any time delay.

[0056] When the number of heterogeneous satellite constellations participating in the collaboration is four, the specific mapping relationship of the two-dimensional resource matrix is ​​as follows:

[0057] The downlink of the first constellation C1 in the first constellation subset A is allocated to the second VHF band F. H Combination with the first orthogonal spreading sequence SS0;

[0058] The downlink of the second constellation C3 in subset A of the first constellation is allocated to the second VHF band F. H Combination with the first orthogonal spreading sequence SS1;

[0059] The downlink of the third constellation C2 in subset B of the second constellation is allocated to the first VHF band F. L Combination with the second orthogonal spreading sequence SS0;

[0060] The downlink of the fourth constellation C4 in subset B of the second constellation is allocated to the first VHF band F. L Combination with the second orthogonal spread spectrum sequence SS1;

[0061] That is, the system configures a set of orthogonal spreading code sequences in the code domain. The orthogonal spreading sequences satisfy strict cross-correlation mathematical properties, meaning that for any different spreading sequences, their spatial cross-correlation function remains constant over any time delay. It approaches zero (below 0.01);

[0062] Define the set of constellations supported by the system as follows Resource allocation function constructed based on a two-dimensional matrix The following mapping relationship is satisfied:

[0063] ;

[0064] ;

[0065] ;

[0066] ;

[0067] in, and , ;

[0068] This represents the bulletin board resources allocated to the i-th constellation, which is the combination of the physical frequency band (Freq) and the orthogonal spread spectrum sequence (SS) used by that constellation to broadcast its bulletin board (SBB) signals.

[0069] Choosing the number of orthogonal spreading codes is an art of balancing communication bandwidth, data rate, terminal computing power, and space physical requirements. Blindly increasing the number of spreading code types, while seemingly increasing "theoretical capacity," can actually lead to irreversible consequences such as a sharp drop in data rate, increased latency, algorithm failure, and multiple access noise overwhelming the channel. Locking the orthogonal codes to two types (SS0, SS1), combined with frequency domain mirror misalignment (FL, FH), is the optimal engineering solution for maximizing space collisions with minimal engineering complexity. In practical applications, satellite bulletin boards typically allocate 1-2 bits for the spreading codes; currently, only 1 bit (0 and 1) is used.

[0070] Step 4: Configure a unified roaming ID and a unique network ID for each heterogeneous satellite constellation participating in the collaboration. The unified roaming ID is configured to be universal across all heterogeneous satellite constellations participating in the collaboration, while the network ID is configured to be independent for each constellation and is used to identify the constellation to which the data payload belongs after the handover is completed.

[0071] Specifically, the Roaming ID is for all constellations that have signed the collaborative agreement (such as...). , , , A unified logical identifier is assigned to the entire network, allowing terminals to move freely between multiple constellations. Each constellation retains its original physical network identifier, which is used to distinguish the routing, billing, priority, and data payload affiliation of different operators during the data exchange phase after access.

[0072] The shipborne terminal uses a built-in logic state machine to continuously monitor the bulletin board beacons and signal quality of neighboring constellations while connecting to the current constellation. When it detects that the roaming identifier of a neighboring constellation is the same as that of the current constellation and that the signal quality is better than that of the current constellation, it performs a switch from the current constellation to the neighboring constellation.

[0073] As one specific implementation, the shipborne terminal uses a built-in logic state machine to connect to the current constellation C. i Simultaneously, utilizing the baseband software-defined radio (SDR) multi-path despreading parallel processing mechanism, it performs real-time demodulation and resolution of neighboring constellation C. j A continuously broadcast Satellite Bulletin Board (SBB). Extract the Network ID (C) from it. j ), Roaming ID (C jThe shipborne terminal's underlying state machine performs a comparison operation on the extracted Roaming ID.

[0074] If and only if the following conditions are met,

[0075] ,

[0076] Judgment C j Enter candidate switching state;

[0077] in, Adjacent constellations The signal level at time k, For the current zodiac sign The signal level at time k, This is the threshold value for the level difference between the two. Current constellation. and adjacent constellations The signal level is obtained by the shipborne terminal itself through energy detection or signal-to-noise ratio measurement of the received signal.

[0078] like This indicates that it does not belong to a unified collaborative network, so the evaluation should be abandoned directly.

[0079] like This indicates that the signal advantage has not reached the set margin, and the hysteresis timing will not be triggered.

[0080] Simultaneously, a sliding counter is used to control switching hysteresis, only when the target constellation... Continuous signal quality Each sampling period ( (Values ​​range from 5 to 10) Stably exceed the current constellation Da Only after these conditions are met will the final switch be triggered. Any signal drop during the process will cause the counter to reset to zero, thus completely eliminating the frequent ping-pong effect.

[0081] In practical applications, the switching threshold is usually used. Setting it to 3dB means that the signal power of the target neighboring constellation must be more than twice that of the current constellation. This ensures that each handover brings a substantial and perceptible improvement in communication link quality, avoiding the cost of handover for minor signal improvements.

[0082] If the logical determination is valid, the shipborne terminal directly identifies the other party as belonging to the unified protocol network, skipping complex signaling exchanges such as identity addressing and authentication. The terminal utilizes the target constellation C... j The information on the bulletin board indicates that the Doppler frequency shift of the uplink carrier is calculated in advance and pre-compensation for the transmission frequency is performed; at the same time, the physical channel is adjusted to C. jThe corresponding mirrored duplex frequency bands (FL / FH) and orthogonal spreading codes (SS0 / SS1). The terminal completely bypasses the four time-consuming steps of "system re-blind network search," "blind synchronization of radio frequency bands," "core network roaming authentication," and "network registration and location update," directly using C... j The random access or pre-allocated time slot specified on the bulletin board will send the original physical Network ID and service data packets together to C. j Instantaneous launch. Constellation C j Upon receiving the data packet, since the Roaming ID verification has been passed by default, the data packet is forwarded directly. The shipborne terminal automatically completes the routing of business data between different operators, tariff settlement and priority management based on the original Network ID retained in the data packet, thus realizing a closed loop of supervision and operation.

[0083] Based on a unified Roaming ID across the entire network and a carrier-specific Network ID, barriers between carriers can be eliminated, even if and Even though they belong to different commercial space companies, as long as they share a unified Roaming ID, the terminals can achieve seamless transitions between the physical and network layers. This ensures business continuity; in long-distance ocean communications, this "seamless" switching ensures that highly time-sensitive services such as video conferencing and real-time weather data transmission will not experience link interruptions of several seconds or even longer due to constellation switching. Furthermore, identification decoupling ensures that while seamless switching is achieved through the Roaming ID, the system still uses independent Network IDs to distinguish data payloads from different constellations, guaranteeing the independence of billing, routing, and attribution management.

[0084] Both the shipborne terminal and the satellite terminal are equipped with bandpass filters. These bandpass filters are used to suppress interference signals in opposing frequency bands outside the target receiving frequency band. High-quality marine-grade filters can achieve a suppression efficiency of up to several MHz at intervals of [missing value]. That is, 10 -6 .

[0085] When multiple satellite constellations (such as , , , When data is broadcast to the ground concurrently in the same overlapping airspace, the composite signal received by the shipborne terminal receiver on the ground is: Signal-to-noise ratio of useful signals received by shipborne terminals The calculation formula is as follows:

[0086] ;

[0087] ;

[0088] in , , These are the transmit power, useful signal, and channel gain of the target constellation satellites, respectively. , , This is to provide co-frequency interference signals to other overlapping constellation satellites; and All represent additive white Gaussian noise; N is the number of VDES heterogeneous low-Earth orbit satellite constellations participating in the coordination.

[0089] In a high-altitude environment, the free-space loss and channel gain of various low-Earth orbit satellites to the ground. The extremely close proximity results in the sum of co-frequency interference power in the denominator being much greater than the noise floor. .at this time The value approaches 0 or even becomes negative, which directly causes nonlinear blocking and saturation overload of the receiver front-end radio frequency low noise amplifier (LNA), resulting in the complete disconnection of the underlying physical link of the satellite system.

[0090] In the mirror-duplex environment of this embodiment, the signal-to-noise ratio of the useful signal when the shipborne terminal receives satellite signals from subset A is... The calculation method is as follows:

[0091] ;

[0092] Since the filter's suppression attenuation factor α tends to 0 ( That is, 10 -6 Then, all downlink satellite co-channel interference from subset B is completely suppressed below the noise floor, therefore:

[0093] ;

[0094] Among them, constellations For the target satellite currently being received by the shipborne terminal, P a and H a These are its transmit power and channel gain, respectively. Indicates the other interfering constellations in subset A. Let C represent the constellations in subset B. SNR′ represents the signal-to-noise ratio in a mirror-duplex environment. In subset A, excluding C... a Other constellations are designated C a′ P a′ and H a′ Its corresponding transmit power and channel gain; the constellation in subset B is denoted as C. b′ The corresponding power P b′ Channel gain H b′ .

[0095] After this mirroring process, the system successfully reduced the number of N-1 strong interference sources in the original overlapping area by more than half.

[0096] Therefore, when these two subsets of satellites operate in the same airspace (same coverage area) and perform multi-constellation scheduling, their anti-jamming advantages are reflected in the following two dimensions: First, complete frequency domain misalignment and isolation. When satellites in constellation A are transmitting signals to the ground at high power (using...) If satellites from constellation B are also launched, they will use the low-frequency band. This can avoid multiple satellites in constellations A and B simultaneously being in the same location. or The transmission effectively prevented downlink co-channel interference for the ground-based shipborne terminal, making it impossible to demodulate either signal; secondly, the efficient coordination of radio frequency filters. Both the shipborne terminal and the satellite terminal are equipped with bandpass filters. Because... and There are frequency intervals of several MHz between them, and the filter can easily filter out the energy leakage of opposing frequency bands. After constructing the physical link foundation of mirror duplex, the system effectively isolates the transmit interference between constellations by frequency domain inversion, ensuring the purity of the underlying transmit and receive link.

[0097] This invention introduces a two-dimensional mapping matrix composed of physical channels and spreading sequences, evolving from simple frequency allocation to multi-dimensional resource management. Utilizing the orthogonality of spreading technology, it achieves efficient demodulation of multiple concurrent beacon signals without altering the hardware RF link, thereby transforming the anti-interference advantages of the physical layer into high-concurrency access capabilities at the link layer. This enables more precise identification and access to specific constellations in complex electromagnetic environments, resolving the collision problem of multiple satellite beacons in the same space.

[0098] The shipborne terminal requires no additional physical RF antennas or hardware demodulation links. It achieves perfect signal stripping from four concurrent satellite constellation beacons on a single hardware device solely through software-defined radio (SDR) baseband logic control. The core demodulation process formulas and logic decisions are as follows:

[0099] ;

[0100] in For the first Spatial fading coefficient of constellation signals, Modulate the signal for its original bulletin board. It is additive white Gaussian noise.

[0101] Modulate the original bulletin board signal for the nth constellation; The frequency (F) used for the nth constellation L or FH ); The spreading code sequence used for the nth constellation.

[0102] The terminal receiver state machine adopts a two-dimensional orthogonal mode. First, frequency domain separation is performed. The mixer and digital bandpass filter (BPF) at the receiver front end utilize F... L and F H The wide-span isolation in the frequency domain directly separates the signal into two parallel baseband data streams. High (t) and r Low (t):

[0103] ;

[0104] ;

[0105] in, and These represent high-frequency filters and low-frequency filters, respectively. and These are the additive white Gaussian noise remaining after bandpass filtering in the high-frequency and low-frequency branches, respectively.

[0106] Subsequently, code domain demodulation is performed. On each frequency domain line, the digital signal processor (DSP) utilizes the autocorrelation and cross-correlation of the orthogonal spreading code to perform despreading operations through a matched filter, obtaining the respective bulletin board payload. , , , :

[0107] ;

[0108] ;

[0109] ;

[0110] ;

[0111] , , , These are the additive white Gaussian noise remaining after integration of the four despreading branches through matched filtering.

[0112] After processing in the frequency domain and code domain, even constellations , , , By simultaneously transmitting satellite signals in the same space, the shipborne receiver can correctly obtain the payload information of each of its respective bulletin boards, thus enabling simultaneous transmission and reception of four constellations.

[0113] After the mirror duplex and spread spectrum sequence fusion mechanism, the shipborne terminal does not require additional RF hardware links. Using only Software Defined Radio (SDR) logic, a single device can simultaneously demodulate signals from four constellations, achieving hardware upgrades without the need for additional RF hardware. Simultaneously, it completely resolves the collision problem of signals on the same frequency, even... and All Transmitted, but because of their spreading codes ( and The two are orthogonal, and the receiver can effectively separate them using code division techniques.

[0114] like Figure 1 As shown, the process of two-dimensional (frequency domain × code domain) concurrent demodulation of four constellation bulletin boards by a shipborne terminal in a multi-constellation superposition environment is demonstrated. It shows that the shipborne terminal can realize the complete receiver process of collision-free and concurrent demodulation of four heterogeneous constellation bulletin boards at the physical layer by using mirror duplex and orthogonal spreading codes in the high-density superposition coverage of multiple constellations.

[0115] Input phase: Shipborne antenna receives overlapping radio frequency signals from multiple spatial constellations. (also includes) , , , Signal).

[0116] First dimension: Frequency domain separation (mirror-image duplex): Through a mixer and a bandpass filter (BPF), based on the high-frequency band... (161.900-161.925 MHz) and low frequency band (157.300-157.325 MHz) Wide-span isolation, separating high-frequency data streams. With low-frequency data stream .

[0117] Second dimension: Code domain demodulation (quadrature spread spectrum): Digital signal processor for... Matched filtering despreading is performed using orthogonal spreading codes SS0 and SS1 to separate the constellation. and Notice board and Similarly, for Using SS0 and SS1 despreading, the constellations were separated. and Notice board and .

[0118] Output result: No need for multiple frequency sweeps, a single SDR can concurrently acquire broadcast signals from 4 constellations.

[0119] Example 2

[0120] A VDES anti-interference and cross-network seamless scheduling system in a multi-constellation superposition environment includes:

[0121] The resource allocation module is used to divide the N (2≤N≤4) VDES heterogeneous low-Earth orbit satellite constellations participating in the collaboration into a first constellation subset A and a second constellation subset B, and to configure a forward standard duplex link for the first constellation subset A: the uplink uses the first VHF band F. L The downlink uses the second VHF band F. H Configure a reverse mirrored full-duplex link for the second constellation subset B: the uplink uses the second VHF band F. H The downlink uses the first VHF band F L The first VHF band F L With the second VHF band F H In the frequency domain, they do not overlap, and orthogonal spread spectrum sequences are allocated to each heterogeneous satellite constellation participating in the collaboration, forming a two-dimensional resource matrix composed of physical frequency bands and spread spectrum sequences, with the matrix resources occupied by each constellation not overlapping;

[0122] The two-dimensional matrix bulletin board broadcast module is set at the end of each satellite constellation and is used to broadcast bulletin board beacons according to the combination of physical frequency bands and spread spectrum sequences allocated to the constellation in the two-dimensional resource mapping matrix;

[0123] The SDR baseband demodulation module, located in the shipboard terminal, is used to perform frequency domain filtering and code domain despreading on the received bulletin board beacons via software-defined radio, so as to demodulate bulletin board beacons from different constellations respectively;

[0124] The dual-layer identification management module is used to configure a unified roaming identifier and an independent network identifier for each heterogeneous satellite constellation participating in the collaboration.

[0125] The terminal state machine switching module, located on the shipboard terminal, is used to continuously monitor the beacons of adjacent constellations. When it detects that the roaming identifier of an adjacent constellation is the same as that of the current constellation and that the signal quality is better than that of the current constellation, it triggers the shipboard terminal to perform a switch from the current constellation to the adjacent constellation.

[0126] The SDR baseband demodulation module includes a bandpass filter unit, a mixer unit, and a digital signal processor connected in sequence.

[0127] The out-of-band rejection ratio of the bandpass filter unit is not less than 60dB, which is equivalent to an attenuation factor α ≤ -60dB for out-of-band interference signals, meaning the residual signal power does not exceed 10% of the original signal. -6 ;

[0128] The digital signal processor has a built-in matched filter that stores templates of spread spectrum sequences for each constellation. This matched filter is used to perform code domain despreading and extract bulletin board broadcast information through correlation operations.

[0129] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for VDES anti-interference and seamless cross-network scheduling in a multi-constellation superposition environment, characterized in that, Includes the following steps: Step 1: Divide the N VDES heterogeneous low-Earth orbit satellite constellations participating in the collaboration into two complementary first constellation subsets A and second constellation subsets B, where 2≤N≤4; Step 2: Configure a forward standard duplex link for the first constellation subset A: the uplink uses the first VHF band F. L The downlink uses the second VHF band F H Configure a reverse mirrored full-duplex link for the second constellation subset B: the uplink uses the second VHF band F. H The downlink uses the first VHF band F L The first VHF band F L With the second VHF band F H They do not overlap in the frequency domain; Step 3: Assign orthogonal spread spectrum sequences to each heterogeneous satellite constellation participating in the collaboration, so that the two-dimensional resource matrix composed of physical frequency bands and spread spectrum sequences assigned to each constellation does not overlap; Step 4: Configure a unified roaming identifier and an independent network identifier for each heterogeneous satellite constellation participating in the collaboration.

2. The VDES anti-interference and cross-network seamless scheduling method under a multi-constellation superposition environment according to claim 1, characterized in that, The shipborne terminal uses a built-in logic state machine to continuously monitor the bulletin board beacons and signal quality of neighboring constellations while connecting to the current constellation. When it detects that the roaming identifier of a neighboring constellation is the same as that of the current constellation and that the signal quality is better than that of the current constellation, it performs a switch from the current constellation to the neighboring constellation.

3. The VDES anti-interference and cross-network seamless scheduling method under a multi-constellation superposition environment as described in claim 2, characterized in that, The steps for determining roaming identification and signal quality before constellation switching by the shipborne terminal are as follows: While connecting to the current constellation, the shipborne terminal uses the multi-path despreading parallel processing mechanism of baseband software-defined radio to demodulate and parse the satellite bulletin boards continuously broadcast by neighboring constellations in real time and extract the roaming identifier, which is then compared with the roaming identifier of the current constellation. If the roaming identifier of an adjacent constellation is the same as that of the current constellation, and the difference between the signal level of the adjacent constellation and the signal level of the current constellation is not less than a preset threshold value. When the adjacent constellation is in a state of transition, it is determined that the adjacent constellation has entered the candidate state for switching. Switching hysteresis is controlled by a sliding counter. When continuous The difference between the signal level of adjacent constellations and the signal level of the current constellation in each sampling period is not less than a preset threshold value. At that time, the final switch is triggered, in which, The value is a preset positive integer. If the difference in any sampling period is less than 100%, then the difference is considered to be less than 100%. If the counter is zeroed, then the counter will return to zero.

4. The VDES anti-interference and cross-network seamless scheduling method under a multi-constellation superposition environment as described in claim 1, characterized in that, In step 4, the unified roaming identifier is configured to be universal across all heterogeneous satellite constellations participating in the collaboration, while the network identifier is configured to be independent for each constellation and is used to identify the constellation to which the data payload belongs after the handover is completed.

5. The VDES anti-interference and cross-network seamless scheduling method under a multi-constellation superposition environment according to claim 1, characterized in that, In step 3, the spreading sequence includes a first orthogonal spreading sequence SS0 and a second orthogonal spreading sequence SS1; the cross-correlation function of the first orthogonal spreading sequence SS0 and the second orthogonal spreading sequence SS1 is lower than a preset threshold under any time delay.

6. The VDES anti-interference and cross-network seamless scheduling method in a multi-constellation superposition environment according to claim 5, characterized in that, In step 3, the specific mapping relationship of the two-dimensional resource matrix is ​​as follows: The downlink of the first constellation C1 in the first constellation subset A is allocated to the second VHF band F. H Combination with the first orthogonal spreading sequence SS0; The downlink of the second constellation C3 in subset A of the first constellation is allocated to the second VHF band F. H Combination with the first orthogonal spreading sequence SS1; The downlink of the third constellation C2 in subset B of the second constellation is allocated to the first VHF band F. L Combination with the second orthogonal spreading sequence SS0; The downlink of the fourth constellation C4 in subset B of the second constellation is allocated to the first VHF band F. L Combination with the second orthogonal spread spectrum sequence SS1.

7. The VDES anti-interference and cross-network seamless scheduling method under a multi-constellation superposition environment according to claim 1, characterized in that, Bandpass filters are configured for the shipborne terminal and the satellites in the various heterogeneous satellite constellations participating in the collaboration. The bandpass filters are used to suppress interference signals in opposing frequency bands outside the target receiving frequency band.

8. The VDES anti-interference and cross-network seamless scheduling method under a multi-constellation superposition environment according to claim 1, characterized in that, The first VHF band F L The second VHF band F is a subset of the low-frequency band ranging from 157.300 MHz to 157.325 MHz. H It is a subset of the high-frequency band ranging from 161.900 MHz to 161.925 MHz.

9. A VDES anti-interference and cross-network seamless scheduling system under a multi-constellation superposition environment, characterized in that, include: The resource allocation module is used to divide the N participating VDES heterogeneous low-Earth orbit satellite constellations into a first constellation subset A and a second constellation subset B, and to configure a forward standard duplex link for the first constellation subset A: the uplink uses the first VHF band F. L The downlink uses the second VHF band F H Configure a reverse mirrored full-duplex link for the second constellation subset B: the uplink uses the second VHF band F. H The downlink uses the first VHF band F L The first VHF band F L With the second VHF band F H In the frequency domain, they do not overlap, and orthogonal spreading sequences are allocated to each heterogeneous satellite constellation participating in the collaboration, forming a two-dimensional resource matrix composed of physical frequency bands and spreading sequences. The matrix resources occupied by each constellation do not overlap; where 2≤N≤4. The two-dimensional matrix bulletin board broadcast module is set at the end of each satellite constellation and is used to broadcast bulletin board beacons according to the combination of physical frequency bands and spread spectrum sequences allocated to the constellation in the two-dimensional resource mapping matrix; The SDR baseband demodulation module, located in the shipboard terminal, is used to perform frequency domain filtering and code domain despreading on the received bulletin board beacons via software-defined radio, so as to demodulate bulletin board beacons from different constellations respectively. The dual-layer identification management module is used to configure a unified roaming identifier and an independent network identifier for each heterogeneous satellite constellation participating in the collaboration. The terminal state machine switching module, located on the shipboard terminal, is used to continuously monitor the beacons of adjacent constellations. When it detects that the roaming identifier of an adjacent constellation is the same as that of the current constellation and that the signal quality is better than that of the current constellation, it triggers the shipboard terminal to perform a switch from the current constellation to the adjacent constellation.

10. The VDES anti-interference and cross-network seamless scheduling system under a multi-constellation superposition environment as described in claim 9, characterized in that, The SDR baseband demodulation module includes a bandpass filter unit, a mixer unit, and a digital signal processor connected in sequence. The out-of-band rejection ratio of the bandpass filter unit is not less than 60dB; The digital signal processor has a built-in matched filter that stores templates of spread spectrum sequences for each constellation. This matched filter is used to perform code domain despreading and extract bulletin board broadcast information through correlation operations.

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