A data transmission method between ships based on multi-layer network in VDES
By establishing a multi-layer network structure in the VDES system, combining geosynchronous satellites and low-orbit satellites, and using self-organized ship cells and satellite routing tables for data transmission, the extended and poor reception quality of ship data transmission in the existing technology is solved. The problem has achieved efficient multi-layer network data transmission and improved the quality of maritime communication.
Patent Information
- Application Number
- CN202111296828.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-11-03
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2041-11-03
AI Technical Summary
In the prior art, data transmission between ships has problems such as delayed transmission and poor quality of received data, especially long-distance data transmission relies on geosynchronous satellites, resulting in large path loss and time-lapse prolongation, and the application method of low-orbit satellites has not been Fully develop.
Establish a data transmission method between ships based on multi-layer network in VDES, combine geosynchronous satellites, low-orbit satellites and ships, form a three-layer network structure with upper, middle and lower layers, and use self-organized low-orbit satellites and ships Administrative cells conduct data transmission, select the optimal network for data forwarding based on the location of the source and the lobby ship, reducing dependence on synchronous satellites.
It has achieved simplified data transmission process, reduced transmission delay, improved the quality of received data, ensured that the communication distance is close, the path loss is small, and improved the quality of maritime communication and service satisfaction.
Smart Images
Figure CN113891283B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of wireless communication, and in particular relates to a data transmission method between ships based on a multi-layer network in a VDES. Background Art
[0002] The maritime communication system has gradually transitioned from the traditional Automatic Identification System (AIS) to the VHF Data Exchange System (VDES). The VDES system can comprehensively enhance the data communication capabilities between ships, satellites, and shore stations, and provide a variety of data services such as navigation, collision avoidance, search and rescue, and weather forecasts for ships at sea.
[0003] In the VDES system, some ships that are close to each other form a ship self-organizing cell in a self-organizing manner. Therefore, the data transmission between ships at a short distance adopts the ship multi-hop forwarding method. For data transmission between ships at a long distance, the "IALA G1139" recommendation and existing literature all use geosynchronous satellites as relays to forward data, and use the "ship-synchronous satellite-ship" method to achieve data transmission between ships at a long distance. In other words, the existing data transmission between ships adopts the data transmission method of short-distance ship forwarding and long-distance geostationary satellite forwarding (Short-distance Ship Forwarding and Long-distance Geostationary Satellite Forwarding, SSF-LGF). Geosynchronous satellites are stationary relative to the earth, so the geosynchronous satellite forwarding method is simple to implement, but because geosynchronous satellites are far from the ground and have large path losses, this data transmission method has the problems of extended transmission time and poor quality of received data.
[0004] However, with the proposal of the "space-ground integrated" network, the aerial part of the VDES system is developing towards an aerial network composed of geosynchronous satellites (high-orbit satellites) and low-orbit satellites. For example, the document "Architecture and Key Technologies of Space-Ground-Sea Communication Network Based on VDES" (author Hu Xu, Mobile Communications, Issue 5, 2019, pp. 2-8) and the document "Satellite Communications and 5G (Part 1)" (author Zhong Man, Digital Communications World, September 2020, pp. 1-5) both mention that low-orbit satellites are close to the ground, have short transmission delays, and small path losses, and can be used to transmit data. However, since low-orbit satellites are mobile relative to the ground, this method is more complicated to implement, and no specific method for using low-orbit satellites for data transmission between ships is given in the existing literature. Therefore, how to combine synchronous satellites with low-orbit satellites and find a data transmission method that is simple to implement, has low transmission delays, and has high received data quality is a key issue that needs to be studied in depth, which is of great significance for improving the communication quality and service satisfaction of maritime communications. Summary of the invention
[0005] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a method for data transmission between ships based on a multi-layer network in a VDES. The method combines geosynchronous satellites, low-orbit satellites, and ships to establish a multi-layer network structure. The multi-layer network structure is used to transmit data between ships. This method is not only simple to implement, but also can reduce transmission delay and improve the quality of received data.
[0006] The solution of the present invention to solve the above technical problems is:
[0007] A method for transmitting data between ships based on a multi-layer network in a VDES, the method comprising the following steps:
[0008] Step 1: Establish a multi-layer network structure model:
[0009] Establish an upper, middle and lower three-layer network structure model; the upper network is composed of geosynchronous satellites, and there is one geosynchronous satellite in the network, denoted as φ; the middle network is composed of low-orbit satellites, and there are M low-orbit satellites located within the coverage of the geosynchronous satellite φ, denoted as δ 1 , δ 2 , …, δ M, and the M low-orbit satellites form a low-orbit satellite self-organizing network in a self-organizing manner, wherein each low-orbit satellite stores its own low-orbit satellite routing table, and the content of the low-orbit satellite routing table includes the destination low-orbit satellite and the corresponding next-hop low-orbit satellite; the lower network is composed of ships, and ships that are relatively close form ship self-organizing cells in a self-organizing manner; assuming that each low-orbit satellite can cover Q ship self-organizing cells, each ship self-organizing cell has N ships, and the nth ship in the qth ship self-organizing cell within the coverage of the mth low-orbit satellite is recorded as s man , where m∈{1,2,…,M},q∈{1,2,…,Q},n∈{1,2,…,N}; in each ship self-organizing cell, each ship saves its own ship self-organizing cell routing table, the content of the ship self-organizing cell routing table includes the destination ship in the self-organizing cell and the corresponding next-hop ship; all ships periodically report their low-orbit satellite number, ship self-organizing cell number and ship number to the geosynchronous satellite φ, for example, s mqn The reported low-orbit satellite number, ship self-organizing cell number and ship number are m, q and n respectively. The geosynchronous satellite φ saves and periodically updates this information;
[0010] Step 2: Use a multi-layer network-based data transmission method to carry out ship-to-ship data transmission:
[0011] The specific process of the data transmission method based on multi-layer network is as follows:
[0012] 1) Source ships ija To send a letter to the ship rtb Transmit data, then the source ship s ija Send a request message to the geosynchronous satellite φ to inquire about the destination ship s rtb The low-orbit satellite number, the ship's self-organizing cell number, the ship number, and the geosynchronous satellite φ reply s ija ,s ija Get rtb The low-orbit satellite number r, the ship self-organizing cell number t, and the ship number b, where i, r ∈ {1, 2, ..., M}, j, t ∈ {1, 2, ..., Q}, a, b ∈ {1, 2, ..., N};
[0013] 2) Determine whether i=r and j=t are satisfied at the same time;
[0014] 21) If i = r and j = t are satisfied at the same time, then the source ship s ija With the ship rtb The same ship self-organized cell belongs to the same low-orbit satellite coverage area, then in s ija and rtbIn the self-organizing community of the ship to which it belongs, s ija The data sent is forwarded by the ship's multi-hop according to the ship's self-organizing cell routing table and transmitted to s rtb ;
[0015] 22) If i=r and j=t cannot be satisfied at the same time, jump to sub-step 3);
[0016] 3) Determine whether i=r is satisfied;
[0017] 31) If i=r, then i=r, j≠t, that is, the source ship s ija With the ship rtb Different ships self-organize cells within the coverage of the same low-orbit satellite, then s ija The data sent is first transmitted to the low-orbit satellite δ i , by the low-orbit satellite δ i Find the bth ship s in the tth ship self-organizing cell within its coverage area rtb , and forward the data to s rtb ;
[0018] 32) If i=r is not satisfied, then the source ship s ija With the ship rtb Different ships self-organize cells belonging to different low-orbit satellite coverage areas, then s ija The data sent is first transmitted to the low-orbit satellite δ i , and then perform multi-hop forwarding of low-orbit satellites according to the low-orbit satellite routing table and transmit it to δ r , and then by δ r Find the bth ship s in the tth ship self-organizing cell within its coverage area rtb , and forward the data to s rtb .
[0019] The present invention discloses a data transmission method between ships based on a multi-layer network in a VDES, which has the following beneficial effects compared with the prior art:
[0020] Compared with the existing data transmission method of short-distance ship forwarding and long-distance synchronous satellite forwarding (SSF-LGF), this method combines geosynchronous satellites, low-orbit satellites, and ships to establish a multi-layer network structure, and uses geosynchronous satellites to provide source ships with relevant information of destination ships; if the source ship and the destination ship are close (belonging to the same self-organizing cell), the ship in the lower network is directly used to forward the data; if the source ship and the destination ship are far away, the low-orbit satellite in the middle network is used to forward the data; that is to say, the method of the present invention is judged according to the position of the source ship and the destination ship, and tries to select a lower-level network (ship forwarding or low-orbit satellite forwarding) to transmit data, instead of using synchronous satellites to transmit data. Therefore, the data transmission method between ships based on a multi-layer network disclosed in the present invention can always ensure that the communication distance between the two ships is short, the transmission delay is short, and the path loss is small (the quality of received data is high). In addition, in the upper, middle, and lower multi-layer network structures established by the present invention, there are routing tables in the middle and lower network structures, and data is transmitted by multi-hop forwarding, so it is simple and convenient to implement. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a general flow chart of a data transmission method between ships based on a multi-layer network in a VDES disclosed by the present invention;
[0022] Figure 2 A schematic diagram of a system model of a data transmission method between ships based on a multi-layer network in a VDES disclosed by the present invention;
[0023] Figure 3 It is a flow chart of a data transmission method based on a multi-layer network in a data transmission method between ships based on a multi-layer network in a VDES disclosed by the present invention;
[0024] Figure 4 It is a simulation result diagram of the average bit error rate of received data in a data transmission method between ships based on a multi-layer network in a VDES disclosed by the present invention;
[0025] Figure 5 A simulation result diagram of data transmission delay in a data transmission method between ships based on a multi-layer network in a VDES disclosed by the present invention; DETAILED DESCRIPTION
[0026] The present invention will be further explained below in conjunction with the accompanying drawings.
[0027] Example 1
[0028] like Figures 1 to 3As shown, a data transmission method between ships based on a multi-layer network in a VDES disclosed by the present invention comprises the following steps:
[0029] Step 1: Establish a multi-layer network structure model:
[0030] Establish a three-layer network structure model of upper, middle and lower layers; Figure 2 As shown in the figure, the upper network consists of geosynchronous satellites. Suppose there is one geosynchronous satellite in the network, denoted as φ; the middle network consists of low-orbit satellites. Suppose there are M low-orbit satellites located within the coverage of the geosynchronous satellite φ, denoted as δ 1 , δ 2 , …, δ M , and the M low-orbit satellites form a low-orbit satellite self-organizing network in a self-organizing manner, wherein each low-orbit satellite stores its own low-orbit satellite routing table, and the content of the low-orbit satellite routing table includes the destination low-orbit satellite and the corresponding next-hop low-orbit satellite; the lower network is composed of ships, and ships that are relatively close form ship self-organizing cells in a self-organizing manner; assuming that each low-orbit satellite can cover Q ship self-organizing cells, each ship self-organizing cell has N ships, and the nth ship in the qth ship self-organizing cell within the coverage of the mth low-orbit satellite is recorded as s mqn , where m∈{1,2,…,M},q∈{1,2,…,Q},n∈{1,2,…,N}; in each ship self-organizing cell, each ship saves its own ship self-organizing cell routing table, the content of the ship self-organizing cell routing table includes the destination ship in the self-organizing cell and the corresponding next-hop ship; all ships periodically report their low-orbit satellite number, ship self-organizing cell number and ship number to the geosynchronous satellite φ, for example, s mqn The reported low-orbit satellite number, ship self-organizing cell number and ship number are m, q and n respectively. The geosynchronous satellite φ saves and periodically updates this information;
[0031] Step 2: Use a multi-layer network-based data transmission method to carry out ship-to-ship data transmission:
[0032] The flowchart of the data transmission method based on multi-layer network is as follows Figure 3 As shown, the specific process is as follows:
[0033] 1) Source ships ija To send a letter to the ship rtb Transmit data, then the source ship s ija Send a request message to the geosynchronous satellite φ to inquire about the destination ship s rtb The low-orbit satellite number, the ship's self-organizing cell number, the ship number, and the geosynchronous satellite φ reply s ija,s ija Get rtb The low-orbit satellite number r, the ship self-organizing cell number t, and the ship number b, where i, r ∈ {1, 2, ..., M}, j, t ∈ {1, 2, ..., Q}, a, b ∈ {1, 2, ..., N};
[0034] 2) Determine whether i=r and j=t are satisfied at the same time;
[0035] 21) If i = r and j = t are satisfied at the same time, then the source ship s ija With the ship rtb The same ship self-organized cell belongs to the same low-orbit satellite coverage area, then in s ija and rtb In the self-organizing community of the ship to which it belongs, s ija The data sent is forwarded by the ship's multi-hop according to the ship's self-organizing cell routing table and transmitted to s rtb ;
[0036] 22) If i=r and j=t cannot be satisfied at the same time, jump to sub-step 3);
[0037] 3) Determine whether i=r is satisfied;
[0038] 31) If i=r, then i=r, j≠t, that is, the source ship s ija With the ship rtb Different ships self-organize cells within the coverage of the same low-orbit satellite, then s ija The data sent is first transmitted to the low-orbit satellite δ i , by the low-orbit satellite δ i Find the bth ship s in the tth ship self-organizing cell within its coverage area rtb , and forward the data to s rtb ;
[0039] 32) If i=r is not satisfied, then the source ship s ija With the ship rtb Different ships self-organize cells belonging to different low-orbit satellite coverage areas, then s ija The data sent is first transmitted to the low-orbit satellite δ i , and then perform multi-hop forwarding of low-orbit satellites according to the low-orbit satellite routing table and transmit it to δ r , and then by δ r Find the bth ship s in the tth ship self-organizing cell within its coverage area rtb , and forward the data to s rtb .
[0040] Example 2 (Experimental Example)
[0041] The following is a simulation experiment conducted according to a data transmission method between ships based on a multi-layer network in a VDES disclosed by the present invention, which is compared with the existing data transmission methods of short-distance ship forwarding and long-distance synchronous satellite forwarding (SSF-LGF) to illustrate the feasibility and effectiveness of the method of the present invention.
[0042] During the simulation, the channel is set to AWGN channel, QPSK modulation, the orbital altitude of the low-orbit satellite is 600km, the orbital altitude of the geosynchronous satellite is 36000km, the radius of the ship self-organizing cell is 200 meters, all channels are independent of each other, and the noise variance is 1.
[0043] The simulation results are as follows Figure 4 , Figure 5 As shown, "SSF-LGF" refers to the existing data transmission method of short-distance ship forwarding and long-distance synchronous satellite forwarding; "data transmission based on multi-layer network" refers to the data transmission method between ships based on multi-layer network disclosed in the present invention.
[0044] Figure 4 The horizontal axis is the signal-to-noise ratio, and the vertical axis is the average bit error rate of the received data, which is the statistical average of 100,000 tests. It can be seen from the figure that the bit error rate of "data transmission based on a multi-layer network" is significantly lower than that of "SSF-LGF". This is because "SSF-LGF" uses synchronous satellites to transmit data; while the "data transmission based on a multi-layer network" of the present invention selects a lower-level network (ship forwarding or low-orbit satellite forwarding) to transmit data each time, and does not use synchronous satellites to transmit data; therefore, compared with "SSF-LGF", the communication distance of the method of the present invention is short and the path loss is small, thereby reducing the bit error rate and improving the quality of received data.
[0045] Figure 5 The delay comparison between "SSF-LGF" and "data transmission based on multi-layer network" obtained from the simulation experiment. The vertical axis is the average delay of data transmission, which is the average delay of 10,000 tests. Figure 5 It can be seen that compared with "SSF-LGF", the "data transmission based on multi-layer network" disclosed in the present invention can reduce data transmission delay.
[0046] In summary, the present invention discloses a method for data transmission between ships based on a multi-layer network in a VDES. The method combines geosynchronous satellites, low-orbit satellites, and ships to establish a multi-layer network structure. The multi-layer network structure is used to perform data transmission between ships. This method is not only simple to implement, but also can reduce transmission delay and improve the quality of received data.
Claims
1. A method for data transmission between ships based on a multi-layer network in a VDES, the method comprising the following steps: Step 1: Establish a multi-layer network structure model: A three-layer network structure model is established: upper, middle, and lower. The upper network consists of geosynchronous satellites. Suppose there is one geosynchronous satellite in the network, denoted as φ. The middle network consists of low-orbit satellites. Suppose there are M low-orbit satellites located within the coverage of the geosynchronous satellite φ, denoted as δ1, δ2, …, δ M , and the M low-orbit satellites form a low-orbit satellite self-organizing network in a self-organizing manner, wherein each low-orbit satellite stores its own low-orbit satellite routing table, and the content of the low-orbit satellite routing table includes the destination low-orbit satellite and the corresponding next-hop low-orbit satellite; the lower network is composed of ships, and ships that are relatively close form ship self-organizing cells in a self-organizing manner; suppose that each low-orbit satellite covers Q ship self-organizing cells, and there are N ships in each ship self-organizing cell, and the nth ship in the qth ship self-organizing cell within the coverage of the mth low-orbit satellite is recorded as s mqn , where m∈{1,2,…,M}, q∈{1,2,…,Q}, n∈{1,2,…,N}; in each ship self-organizing cell, each ship saves its own ship self-organizing cell routing table, the content of the ship self-organizing cell routing table includes the destination ship in the self-organizing cell and the corresponding next-hop ship; all ships periodically report their own low-orbit satellite number, ship self-organizing cell number and ship number to the geosynchronous satellite φ, s mqn The reported low-orbit satellite number, ship self-organizing cell number and ship number are m, q and n respectively. The geosynchronous satellite φ saves and periodically updates this information; Step 2: Use a multi-layer network-based data transmission method to carry out ship-to-ship data transmission: The specific process of the data transmission method based on multi-layer network is as follows: 1) Source ships ija To send a letter to the ship rtb Transmit data, then the source ship s ija Send a request message to the geosynchronous satellite φ to inquire about the destination ship s rtb The low-orbit satellite number, the ship's self-organizing cell number, the ship number, and the geosynchronous satellite φ reply s ija ,s ija Get rtb The low-orbit satellite number r, the ship self-organizing cell number t, and the ship number b, where i, r ∈ {1, 2, ..., M}, j, t ∈ {1, 2, ..., Q}, a, b ∈ {1, 2, ..., N}; 2) Determine whether i=r and j=t are satisfied at the same time; 21) If i = r and j = t are satisfied at the same time, then the source ship s ija With the ship rtb The same ship self-organized cell belongs to the same low-orbit satellite coverage area, then in s ija and rtb In the self-organizing community of the ship to which it belongs, s ija The data sent is forwarded by the ship's multi-hop according to the ship's self-organizing cell routing table and transmitted to s rtb ; 22) If i=r and j=t cannot be satisfied at the same time, jump to sub-step 3); 3) Determine whether i=r is satisfied; 31) If i=r, then i=r, j≠t, that is, the source ship s ija With the ship rtb Different ships self-organize cells within the coverage of the same low-orbit satellite, then s ija The data sent is first transmitted to the low-orbit satellite δ i , by the low-orbit satellite δ i Find the bth ship s in the tth ship self-organizing cell within its coverage area rtb , and forward the data to s rtb ; 32) If i=r is not satisfied, then the source ship s ija With the ship rtb Different ships self-organize cells belonging to different low-orbit satellite coverage areas, then s ija The data sent is first transmitted to the low-orbit satellite δ i , and then perform multi-hop forwarding of low-orbit satellites according to the low-orbit satellite routing table and transmit it to δ r , and then by δ r Find the bth ship s in the tth ship self-organizing cell within its coverage area rtb , and forward the data to s rtb .