A method for optimizing the deployment of multi-hop links in narrowband ad hoc networks by integrating 3D propagation modeling

Abstract

A method for optimizing multi-hop link deployment in narrowband ad hoc networks by integrating 3D propagation modeling includes: constructing a 3D spatial view of the deployment area; constructing a directional topology map based on the deployed narrowband intercom ad hoc network base station equipment; classifying propagation path types and estimating propagation path loss for each node in the directional topology map based on the 3D spatial view, and obtaining the estimated path loss from each node to the target point; determining whether there is an effective overlapping area between nodes in the directional topology map; if there is an effective overlapping area, obtaining the deployment point based on the estimated path loss; if there is no effective overlapping area, determining the range of the deployment point, narrowband ad hoc network constraints, and fitness function, and outputting the optimal multi-hop link deployment scheme; implementing the deployment based on the optimal multi-hop link deployment scheme, and monitoring link quality; dynamically adjusting the link deployment based on the monitoring results, significantly improving the accuracy of propagation loss prediction and adapting to diverse scenario requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a narrowband self-organizing network multi-hop link optimization deployment method combined with three-dimensional propagation modeling. BACKGROUND

[0002] Narrowband self-organizing network has the characteristics of flexible deployment, no infrastructure support, strong anti-interference ability, etc., and is widely used in emergency rescue, field operation, Internet of Things terminal interconnection and other scenes. Multi-hop link as the core architecture of narrowband self-organizing network, its deployment rationality directly affects the communication quality, energy efficiency and life cycle of the network.

[0003] The existing narrowband self-organizing network multi-hop link deployment method has the following shortcomings:

[0004] Limitations of propagation model: Most methods use two-dimensional propagation model (such as free space model, Okumura-Hata model), only consider the influence of planar distance on propagation loss, ignore the three-dimensional factors in actual environment (such as terrain undulation, building shielding, vegetation coverage). In complex scenes such as mountainous areas and densely populated cities, the propagation loss calculated by the two-dimensional model has large error, which leads to inaccurate link continuity judgment and easy occurrence of communication interruption or resource waste.

[0005] Single optimization target: Traditional deployment methods mostly take "link connectivity" or "node coverage range" as the single optimization target, without considering the energy consumption characteristics, total length of link and path loss of narrowband self-organizing network, which leads to poor overall performance of the network.

[0006] Poor dynamic adaptability: The existing methods are mostly static deployment, which cannot adjust the link routing and node position in real time according to the changes in environment (such as node movement, change of obstacle shielding, enhancement of channel interference), and when the network environment deteriorates, it is easy to cause problems such as link quality decline and data transmission failure.

[0007] Therefore, there is an urgent need for a narrowband self-organizing network multi-hop link deployment method combined with three-dimensional propagation characteristics, multi-objective optimization and dynamic adjustment capability to solve the defects of the existing technology. SUMMARY

[0008] In order to solve the above technical problems, the purpose of the present application is to provide a narrowband self-organizing network multi-hop link optimization deployment method combined with three-dimensional propagation modeling, comprising the following steps:

[0009] Step s1: constructing a three-dimensional space view of the deployment area, and constructing a direction topology graph based on the accurate position information and propagation direction of the deployed narrowband intercom self-organizing network base station equipment;

[0010] Step s2: performing propagation path type division and propagation path loss estimation on each node in the direction topology graph based on the three-dimensional space view, and obtaining the estimated path loss of each node to the target point;

[0011] Step s3: determining whether there is an effective overlapping area between each node in the direction topology graph, if there is an effective overlapping area, obtaining the to-be-deployed point based on the estimated path loss, if there is no effective overlapping area, determining the to-be-deployed point range, narrowband ad hoc network constraint and fitness function, performing multi-hop link deployment optimization based on the particle swarm algorithm, and outputting the best multi-hop link deployment scheme;

[0012] Step s4: implementing deployment based on the best multi-hop link deployment scheme, and performing link quality monitoring, and dynamically adjusting the link deployment according to the monitoring result.

[0013] Further, the process of constructing the three-dimensional space view of the deployment area includes:

[0014] Obtaining GIS terrain data, laser radar building data and vegetation data of the deployment area;

[0015] Constructing a space coordinate system of the deployment area, extracting the elevation value of each coordinate point in the space coordinate system from the GIS terrain data, constructing a terrain elevation layer, extracting the vertex coordinates, wall contour and material label of each building from the laser radar building data, constructing a building layer, and extracting the coverage range and height of the vegetation from the vegetation data, constructing a vegetation coverage layer;

[0016] Taking the terrain elevation layer as a base layer, superimposing the building layer and the vegetation coverage layer on the terrain elevation layer to obtain the three-dimensional space view.

[0017] Further, the process of constructing the direction topology graph includes:

[0018] Obtaining the accurate position information of each narrowband intercom ad hoc network base station device deployed in the three-dimensional space view and the source base station device and the target base station device in the narrowband intercom ad hoc network base station device, obtaining the propagation direction according to the source base station device and the target base station device, marking each narrowband intercom ad hoc network base station device as a node, and constructing the direction topology graph according to the accurate position information and the propagation direction of each node.

[0019] Further, the process of performing propagation path type division includes:

[0020] Obtaining the narrowband signal operating frequency and communication coverage range of each node, dividing the space slice of each node in the three-dimensional space view according to the communication coverage range, performing gridding processing on the space slice, and dividing the space slice into a plurality of sub-regions;

[0021] acquire the three-dimensional straight line from the node to any target point in the spatial slice of the node, acquire the altitude values of each sampling point on the three-dimensional straight line and the altitude values of each sampling point in the spatial slice, and compare the altitude values of each sampling point on the three-dimensional straight line with the altitude values of each sampling point in the spatial slice;

[0022] If the altitude values of each sampling point are all greater than the altitude values of each sampling point in the spatial slice, the three-dimensional straight line is marked as a line-of-sight link, and if there is a sampling point whose altitude value is less than the altitude value of the sampling point in the spatial slice, the sampling point is marked as an obstacle sampling point, and the three-dimensional straight line is marked as a non-line-of-sight link.

[0023] Further, the process of performing propagation path loss estimation includes:

[0024] When the three-dimensional straight line from the node to the target point is a line-of-sight link, the estimated path loss from the node to the target point is acquired according to the three-dimensional spatial straight line distance between the node and the target point and the narrowband signal operating frequency of the node.

[0025] Further, the process of performing propagation path loss estimation includes:

[0026] When the three-dimensional straight line from the node to the target point is a non-line-of-sight link, the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is acquired, the obstacle range is identified, the obstacle range is divided into a reflecting surface, a sharp edge or an invalid obstacle;

[0027] If the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is an invalid obstacle, the estimated path loss from the node to the target point is acquired according to the three-dimensional spatial straight line distance between the node and the target point and the narrowband signal operating frequency of the node.

[0028] If the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is a reflecting surface, the material attenuation coefficient of the reflecting surface is acquired, and the estimated path loss from the node to the target point is acquired according to the three-dimensional spatial straight line distance between the node and the target point, the narrowband signal operating frequency of the node and the material attenuation coefficient.

[0029] If the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is a sharp edge, the altitude value maximum point of the sharp edge is selected as a diffraction vertex, the perpendicular distance from the diffraction vertex to the three-dimensional straight line and the three-dimensional spatial straight line distances from the diffraction vertex to the node and the target point are acquired, and the estimated path loss from the node to the target point is acquired based on the narrowband signal operating frequency of the node, the perpendicular distance and the three-dimensional spatial straight line distances from the diffraction vertex to the node and the target point.

[0030] Further, if there is an effective overlapping area between the nodes in the directional topology graph, the process of acquiring the to-be-deployed node based on the estimated path loss includes:

[0031] determining whether there is an overlapping sub-region between the spatial slice of the node and the spatial slice of the next node, if there is an overlapping sub-region, obtaining the estimated path loss and the three-dimensional straight line distance between each target point contained in the overlapping sub-region and the node and the next node respectively, accumulating the estimated path loss between each target point and the node and the next node respectively to obtain the total estimated path loss of each target point, and accumulating the three-dimensional straight line distance between each target point and the node and the next node respectively to obtain the total distance of the link;

[0032] performing terrain condition screening on each target point to eliminate target points that do not meet the terrain condition, then performing weighted average on the total estimated path loss and the total distance of the link of each target point to obtain a candidate coefficient of each target point, and comparing the candidate coefficient of each target point with a preset candidate coefficient threshold, if the candidate coefficient of each target point contained in the overlapping sub-region is less than the candidate coefficient threshold, the overlapping sub-region is eliminated;

[0033] marking the overlapping sub-region that is not eliminated as an effective overlapping region, and marking the target point with the highest candidate coefficient in the effective overlapping region as a to-be-deployed point.

[0034] Further, determining the to-be-deployed point range, narrowband ad hoc network constraint and fitness function, and the process of multi-hop link deployment optimization based on the particle swarm algorithm includes:

[0035] if there is no effective overlapping region, obtaining the non-overlapping region between the spatial slice of the node and the spatial slice of the next node, marking the coordinate point range covered by the spatial slice of the node and the next node and the non-overlapping region as a to-be-deployed point range, setting the constraint condition of the to-be-coded point, randomly generating a plurality of multi-hop link deployment schemes based on the to-be-deployed point range and the constraint condition, obtaining the total estimated path loss, the total distance of the link and the total energy consumption in the multi-hop link deployment scheme, constructing a fitness function based on the total estimated path loss, the total distance of the link and the total energy consumption, and obtaining the best multi-hop link deployment scheme based on the multi-hop link deployment scheme and the fitness function through a multi-objective genetic algorithm.

[0036] Further, the process of implementing deployment based on the best multi-hop link deployment scheme includes:

[0037] sending the best multi-hop link deployment scheme to the user end, the user end deploying the narrowband talkback ad hoc network base station equipment according to the coordinate point of the to-be-deployed point in the best multi-hop link deployment scheme, marking the deployed narrowband as a node, and inserting the deployed narrowband talkback ad hoc network base station equipment into the directional topology graph.

[0038] Further, the process of performing link quality monitoring and dynamically adjusting the link deployment according to the monitoring result includes:

[0039] Each node in the directional topology graph periodically sends a detection data packet to an adjacent node, the detection data packet comprising an effective radiation power, a transmitting antenna gain and a transmitting cable loss, the adjacent node obtaining a signal strength of the received detection data packet, and obtaining a path loss according to the effective radiation power, the transmitting antenna gain, the transmitting cable loss and the signal strength;

[0040] Obtaining an estimated path loss between the node and the adjacent node, comparing the path loss between the node and the adjacent node with the estimated path loss, obtaining a path loss deviation, comparing the path loss deviation with a preset path loss error threshold, and if the path loss deviation is greater than the path loss error threshold, performing step s3 for the node and the adjacent node.

[0041] Compared with the prior art, the present application has the beneficial effects that:

[0042] I. Breakthrough the limitations of traditional two-dimensional propagation model, significantly improve the accuracy of propagation loss estimation

[0043] The present application constructs a three-dimensional space visualization by fusing GIS terrain data, laser radar building data and vegetation data, fully integrates three-dimensional environmental factors such as terrain elevation, building outline and material, vegetation coverage range and height into propagation analysis, and completely gets rid of the limitations of traditional two-dimensional propagation model which only relies on plane distance. In the process of path loss estimation, not only the line-of-sight / non-line-of-sight link type from the node to the target point can be accurately identified, but also the different obstacle characteristics such as reflection surface and sharp edge in the non-line-of-sight link can be differentiated to calculate the loss (such as reflection surface superposition material attenuation coefficient, sharp edge based on diffraction vertex parameter to calculate diffraction loss), instead of general estimation. This fine three-dimensional propagation analysis effectively avoids the loss calculation deviation caused by the two-dimensional model ignoring factors such as terrain undulation and building shielding, thereby reducing the link interruption judgment error, preventing resource waste caused by excessive deployment of nodes due to misjudgment of link interruption, and avoiding the risk of communication interruption caused by misjudgment of link availability, providing more actual scene matching loss data support for subsequent multi-hop link deployment.

[0044] II. Realize multi-target collaborative optimization, and comprehensively improve the overall performance of the network

[0045] In view of the short board of network performance caused by the traditional deployment method taking "link connectivity" or "node coverage" as a single target, the application brings the key indicators such as the total path loss, the total link distance and the total node energy consumption into the multi-objective optimization system. When there is an effective overlapping area, the candidate coefficient is calculated by the weighted average of the loss and the distance through the topographic condition screening of the target point, to ensure that the to-be-deployed point meets the topographic feasibility and balances the loss and the link length. When there is no effective overlapping area, the best deployment scheme is generated by constructing a fitness function integrating the above indicators and combining the particle swarm algorithm, instead of only pursuing a single connectivity or coverage. This multi-objective collaborative optimization logic can fully adapt to the characteristics of narrowband self-organizing network, that is, it can guarantee the communication quality by reducing the path loss and shortening the total link distance, avoid excessive energy consumption of some nodes by controlling the total energy consumption, balance the node energy consumption, prolong the overall network life cycle, avoid the problems such as "slow communication" and "energy consumption imbalance" caused by traditional single-target optimization, and realize the collaborative improvement of network in the dimensions of communication quality, energy consumption efficiency and link stability.

[0046] III. Dynamically adapt to environmental changes to ensure long-term stable operation of the network

[0047] Compared with the defect that the traditional static deployment method cannot cope with environmental changes, the application constructs a closed-loop mechanism of "link quality monitoring-dynamic adjustment". Each node in the directional topology map regularly sends detection data packets containing key parameters such as effective radiated power and antenna gain to adjacent nodes, the adjacent nodes can calculate the actual path loss based on the received signal strength, and compare it with the pre-estimated path loss to judge whether the loss deviation exceeds the threshold. When the environment changes (such as the change of link distance caused by node movement, the sudden increase of loss caused by temporary obstacles, and the influence of signal strength caused by enhanced channel interference), if the loss deviation exceeds the threshold, the system will automatically re-execute the multi-hop link deployment optimization process to adjust the deployment scheme for the affected nodes and adjacent nodes, instead of completely reconstructing the whole network. This dynamic adjustment capability ensures that the network can respond to environmental fluctuations in real time, avoids problems such as link quality decline and data transmission failure caused by environmental deterioration, and significantly improves the adaptability and stability of the network in dynamic scenarios, especially in application scenarios such as emergency rescue and field operation where the environment is easily changed.

[0048] IV. Improve deployment pertinence and flexibility to adapt to diversified scene requirements

[0049] The present application makes the multi-hop link deployment more targeted and flexible through the accurate definition of the direction topology graph and the range of the to-be-deployed points. On the one hand, the direction topology graph is constructed with the propagation direction of the source base station and the target base station as the core, focusing on the directional requirements of the actual communication task, avoiding the resource waste caused by the "undifferentiated coverage" in the traditional deployment, and making the link planning more suitable for specific communication targets. On the other hand, differentiated deployment strategies are provided for the two cases of "there is an effective overlapping area" and "there is no effective overlapping area" between nodes. When there is an overlapping area, the optimal to-be-deployed point is selected from the effective overlapping area. When there is no overlapping area, the range of the to-be-deployed point is defined and the scheme is generated through algorithm optimization, without relying on fixed deployment templates. This differentiated strategy makes the method adaptable to both continuous coverage scenarios and coverage gap scenarios, and the comprehensive coverage of the three-dimensional space view on the terrain, buildings and vegetation makes the method flexible to be applied to different complex environments such as mountains, urban dense areas and wild areas, breaking the dependence of the traditional deployment method on specific scenarios.

[0050] V. Reduce the deployment threshold and improve the deployment efficiency and operability

[0051] The present application significantly reduces the deployment threshold of the narrowband ad hoc network multi-hop link through the deployment mode of "scheme output-user end guidance". The system directly sends the best multi-hop link deployment scheme (including the accurate coordinates of the to-be-deployed points) calculated to the user end, so that the user does not need to have complex wireless propagation theory knowledge and can complete the base station equipment deployment according to the coordinates, avoiding the complicated process of relying on manual survey and trial-and-error adjustment in the traditional deployment. At the same time, the marking of the deployed nodes and the dynamic insertion of the newly deployed nodes in the direction topology graph ensure the continuity of the deployment process without the need to repeatedly construct the network topology. The automatic processing of the path type division and loss estimation also reduces the manual intervention link, further improving the deployment efficiency. This "algorithm dominant calculation-user convenient execution" mode enables non-professionals to complete accurate deployment, expanding the scope of the applicable population of the method, especially in time-critical and limited professional scenarios such as emergency rescue, reliable multi-hop communication links can be quickly established. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 The principle diagram of the narrowband ad hoc network multi-hop link optimization deployment method of the present application embodiment fuses three-dimensional propagation modeling. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0054] As Figure 1 shown, the narrowband self-organizing network multi-hop link optimization deployment method combined with three-dimensional propagation modeling includes the following steps:

[0055] Step s1: Construct a three-dimensional space view of the deployment area, and construct a direction topology graph based on the accurate position information and propagation direction of the deployed narrowband intercom self-organizing network base station device;

[0056] Step s2: Based on the three-dimensional space view, the propagation path type of each node in the direction topology graph is divided and the propagation path loss is estimated, and the estimated path loss of each node to the target point is obtained;

[0057] Step s3: Determine whether there is an effective overlapping area between the nodes in the direction topology graph, if there is an effective overlapping area, obtain the to-be-deployed point based on the estimated path loss, if there is no effective overlapping area, determine the to-be-deployed point range, narrowband self-organizing network constraints and fitness function, and perform multi-hop link deployment optimization based on the particle swarm algorithm, and output the best multi-hop link deployment scheme;

[0058] Step s4: Based on the best multi-hop link deployment scheme, implement the deployment and perform link quality monitoring, and dynamically adjust the link deployment according to the monitoring results.

[0059] It needs to be further explained that in the specific implementation process, the process of constructing the three-dimensional space view of the deployment area includes:

[0060] Obtain the GIS terrain data of the deployment area through GIS means, obtain the laser radar building data of the deployment area through laser radar, and obtain the vegetation data of the deployment area through satellite remote sensing;

[0061] Construct a space coordinate system (composed of xyz axes) of the deployment area, extract the elevation z value of each coordinate point (x, y) in the space coordinate system from the GIS terrain data, construct a terrain elevation layer, extract the vertex coordinates (x, y, z) of each building, wall contour (such as the cuboid model of the tent: 5m long, 3m wide, and 3m high, the bottom coordinates (2500m, 3500m, 700m)) and material label (such as "canvas" and "concrete") from the laser radar building data, and construct a building layer, extract the coverage range (such as (1800-2200m, 2800-3200m)) and height (such as 1.5m on average) of the vegetation from the vegetation data, and construct a vegetation coverage layer;

[0062] Take the terrain elevation layer as the base layer, superimpose the building layer and the vegetation coverage layer on the terrain elevation layer, and obtain the three-dimensional space view.

[0063] Each object in the three-dimensional space view includes: spatial position (x, y, z range); physical properties (building material, vegetation height, terrain slope).

[0064] It should be further explained that, in the specific implementation process, the process of constructing the direction topology graph based on the accurate position information and the propagation direction of the deployed narrowband intercom ad hoc network base station equipment includes:

[0065] The accurate position information of each narrowband intercom ad hoc network base station equipment deployed in the three-dimensional space view and the source base station equipment and the target base station equipment in the narrowband intercom ad hoc network base station equipment are obtained, for example, in a mountainous area emergency scene, the communication task is "mountain foot rescue base station (source base station equipment) -> mountain top command center (target base station equipment)", the data flow direction is fixed as "mountain foot -> mountain slope -> mountain top", which is the "direction anchor point" for subsequent screening of forward and backward jumps; each narrowband intercom ad hoc network base station equipment is equipped with a GPS positioning module, which automatically obtains and reports its current accurate position information (including longitude, latitude and height), as well as its radio frequency (RF) transmission power, energy consumption and working frequency to the central server through its network and radio frequency, and the propagation direction is obtained according to the source base station equipment and the target base station equipment, each narrowband intercom ad hoc network base station equipment is marked as a node, and the direction topology graph is constructed according to the accurate position information of each node and the propagation direction (the node corresponding to the source base station equipment is taken as the starting node of the direction topology graph, the node corresponding to the target base station equipment is taken as the end node of the direction topology graph, the straight line distance between each node and the starting node is obtained, the node with the shortest straight line distance from the starting node is selected as the next node pointed to by the starting node, and then the node with the shortest straight line distance from the starting node other than the next node is selected as the next node pointed to by the next node, and so on, to construct the direction topology graph, the shorter the straight line distance between the node and the starting node in the direction topology graph, the closer the position).

[0066] It should be further explained that, in the specific implementation process, the process of dividing the propagation path type of each node in the direction topology graph based on the three-dimensional space view includes:

[0067] The narrowband signal working frequency and the communication coverage range of each node are obtained, the spatial slice of each node is divided in the three-dimensional space view according to the communication coverage range (the accurate position information of the node is taken as the center point of the communication coverage range, and the three-dimensional space view in the communication coverage range is cut from the three-dimensional space view to make a spatial slice), the spatial slice is gridded, the spatial slice is divided into a plurality of sub-regions, and then the following steps are performed:

[0068] Step A: Constructing path analysis profile and generating sampling points. For any node (transmitting point) and potential target point (receiving point) in the directional topology graph, first obtain the accurate 3D coordinates of both points including antenna height. Based on the two points' coordinates, construct a geometric straight line connecting the two points in 3D space, which represents the theoretical propagation path of the signal in the case of no obstruction. Then, discretize the geometric straight line path with a preset horizontal resolution (e.g. every 1 meter), generating a series of signal simulation sampling points. Each sampling point contains its accurate 3D spatial coordinates, where the altitude represents the point's altitude on the unobstructed straight-line propagation path.

[0069] Step B: Extracting ground altitude using 3D space visual map. For each signal simulation sampling point generated in Step A, query its horizontal coordinates in the 3D space visual map to extract the real ground altitude at that location. This process deeply integrates various data from the 3D map:

[0070] First, query the basic terrain altitude of the coordinate point from the terrain elevation layer.

[0071] Next, query the building layer to determine whether the coordinate point falls within the building outline. If so, obtain the actual height of the building and add it to the terrain altitude.

[0072] Then, query the vegetation coverage layer to determine whether the coordinate point is within the vegetation coverage. If so, obtain the average height of the vegetation and add it to the terrain altitude.

[0073] Finally, the effective ground altitude at this location is determined as the maximum value among the terrain, building, and vegetation heights, which accurately represents the highest point of potential obstacles at that point.

[0074] Step C: Point-by-point comparison and path type determination. Compare the straight-line propagation altitude of each signal simulation sampling point on the path with its corresponding ground altitude one by one:

[0075] If for all sampling points on the path, their straight-line propagation altitude is greater than their corresponding ground altitude, i.e. the condition is met, it proves that there are no obstacles on the signal propagation path, and the path is marked as a Line-of-Sight (LOS) link.

[0076] If there is at least one sampling point on the path, the straight-line propagation altitude of which is less than or equal to the corresponding ground surface altitude, i.e. the condition is met, it is proved that the signal propagation path is blocked by the terrain or the object (such as mountains, buildings) of the point. The path is immediately marked as a Non-Line-of-Sight (NLOS) link, and the first sampling point that meets this condition is identified as an obstacle sampling point, and the corresponding geographical entity is the main obstacle of the path.

[0077] It needs to be further explained that, in the specific implementation process, the process of estimating the propagation path loss includes:

[0078] When the three-dimensional straight line from the node to the target point is a Line-of-Sight (LOS) link (direct path), the estimated path loss from the node to the target point is obtained according to the three-dimensional spatial straight-line distance (non-planar distance) between the node and the target point and the narrowband signal operating frequency of the node .

[0079] ;

[0080] wherein, is a fixed constant after unit conversion, which is applicable to the scenario where the unit of f is MHz and the unit of d is km in the present application, represents a logarithmic function, is the narrowband signal operating frequency, is the three-dimensional spatial straight-line distance between the node and the target point.

[0081] It needs to be further explained that, in the specific implementation process, the process of estimating the propagation path loss includes:

[0082] When the three-dimensional straight line from the node to the target point is a Non-Line-of-Sight (NLOS) link, the obstacle range to which the obstacle sampling point belongs in the three-dimensional straight line is obtained, for example: sampling points are taken along the three-dimensional straight line with a "step length = 0.5 m" (less than 1 times the wavelength of the narrowband signal, to ensure that no occlusion is missed), and it is checked whether each sampling point (x_t, y_t, z_t), wherein t = 1, 2,..., nd, nd represents the total number of sampling points of the three-dimensional straight line, falls within the obstacle range:

[0083] Terrain occlusion: compare the sampling point z_t with the terrain elevation z_terrain of the corresponding (x_t, y_t), if z_t < z_terrain (e.g. sampling point z = 730m, terrain elevation z_terrain = 740m), the ray is occluded by terrain; Building occlusion: check if the sampling point is within the spatial range of a building (e.g. sampling point (2500m, 3500m, 702m) falls within the x (2500-2505m), y (3500-3503m), z (700-703m) range of the tent), the ray is occluded by the building; Vegetation occlusion: if the sampling point falls within the "vegetation occlusion area" and z_t < vegetation height + terrain elevation (e.g. sampling point z = 701m, vegetation height 1.5m, terrain elevation 700m, 701 < 700 + 1.5), the ray is occluded by vegetation;

[0084] Feature recognition of obstacle range, divide the obstacle range into reflective surface, sharp edge (terrain elevation sudden change, such as ridge (slope ≥ 30°, e.g. at (2200m, 3000m) the elevation suddenly rises from 720m to 750m, forming a ridge line), cliff edge, corner of building, such as corner of tent (vertical line from (2505m, 3503m, 700m) to (2505m, 3503m, 703m)), eave corner of concrete building, boundary of large vegetation area, such as intersection line (2200m, 2800-3200m) of shrub area and open area, vegetation height suddenly drops from 1.5m to 0 at the edge) or invalid obstacle;

[0085] Wherein, the process of feature recognition of obstacle range includes:

[0086] Compare the obstacle area, material reflectance and surface roughness in the obstacle range with the preset area threshold (area threshold is 1m², e.g. front wall of tent (3m x 3m = 9m²), concrete wall (10m x 5m = 50m²), exclude small metal parts (e.g. 0.2m x 0.3m equipment shell)), material reflectance threshold (material reflectance threshold is 0.3, reference ITU-R standard, e.g. concrete reflectance 0.4-0.6, metal 0.8-0.9, canvas 0.2-0.3, only concrete and metal are included in reflective surface) and surface roughness threshold (surface roughness threshold is 0.1m, e.g. tent wall is flat, meets the reflection condition; rough rock surface roughness ≥ 0.5m, reflection signal scattering is serious, excluded), if the obstacle area in the obstacle range is greater than the preset area threshold, the material reflectance is greater than the material reflectance threshold, and the surface roughness is less than the preset surface roughness threshold, the obstacle range is divided into reflective surface;

[0087] If the area of the obstacle in the obstacle range is less than or equal to a preset area threshold, or the material reflection coefficient is less than or equal to a material reflection coefficient threshold, or the surface roughness is greater than or equal to a preset surface roughness threshold, the altitude variation coefficient in the obstacle range is obtained, the altitude variation coefficient is compared with a preset altitude variation threshold, if the altitude variation coefficient is greater than the preset altitude variation threshold, the obstacle range is divided into a sharp edge, and if the altitude variation coefficient is less than or equal to the preset altitude variation threshold, the obstacle range is divided into invalid obstacles;

[0088] If the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is invalid obstacle (equivalent to direct path), the estimated path loss from the node to the target point is obtained according to the three-dimensional space straight line distance (non-planar distance) between the node and the target point and the narrowband signal operating frequency of the node ;

[0089] If the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is a reflecting surface (reflection path), the material attenuation coefficient of the reflecting surface is obtained, and the estimated path loss from the node to the target point is obtained according to the three-dimensional space straight line distance (non-planar distance) between the node and the target point, the narrowband signal operating frequency of the node and the material attenuation coefficient of the reflecting surface ;

[0090] ;

[0091] wherein, is a fixed constant after unit conversion, represents a logarithmic function, is the narrowband signal operating frequency, is the three-dimensional space straight line distance between the node and the target point, is the material attenuation coefficient of the reflecting surface;

[0092] If the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is a sharp edge (signal propagation around the edge of the obstacle (such as a terrain ridge or a building corner), which plays a major role only when the direct and reflection paths are blocked or the signal is extremely weak), the altitude value maximum point of the sharp edge is selected as the diffraction vertex, the perpendicular distance from the diffraction vertex to the three-dimensional straight line and the three-dimensional space straight line distances from the diffraction vertex to the node and the target point are obtained, and the estimated path loss from the node to the target point is obtained based on the narrowband signal operating frequency of the node, the perpendicular distance and the three-dimensional space straight line distances from the diffraction vertex to the node and the target point .

[0093] ;

[0094] ;

[0095] wherein, denotes a diffraction parameter (describing the degree of obstruction of the signal by the obstacle), denotes a Fresnel integral function (describing the diffraction field intensity distribution), denotes a narrowband signal operating frequency, denotes a logarithmic function, denotes a vertical distance, denotes a three-dimensional spatial straight-line distance from the diffraction vertex to the node, denotes a three-dimensional spatial straight-line distance from the diffraction vertex to the target point.

[0096] It needs to be further explained that, in the specific implementation process, if there is an effective overlap area between the nodes in the direction topology graph, the process of obtaining the to-be-deployed point based on the estimated path loss includes:

[0097] determining whether there is an overlap sub-area between the spatial slice of the node (except the last node) in the direction topology graph and the spatial slice of the next node, if there is an overlap sub-area, obtaining the estimated path loss and the three-dimensional spatial straight-line distance between each target point (the target point can overlap with the next node, and cannot overlap with the node) included in the overlap sub-area and the node and the next node respectively, accumulating the estimated path loss between each target point and the node and the next node respectively to obtain the estimated path loss sum of each target point, and accumulating the three-dimensional spatial straight-line distance between each target point and the node and the next node respectively to obtain the link total distance;

[0098] performing terrain condition screening on each target point, and eliminating the target points that do not meet the terrain conditions (slope ≤ 10°, no large obstacles (such as rocks, trees), ground bearing ≥ 5 kg (supporting portable base station)), then performing weighted average (the weight coefficients corresponding to the estimated path loss sum and the link total distance are set by expert experience) on the estimated path loss sum and the link total distance of each target point to obtain the candidate coefficient of each target point (the lower the estimated path loss sum and the shorter the link total distance, the higher the candidate coefficient), and comparing the candidate coefficient of each target point with a preset candidate coefficient threshold, if the candidate coefficient of each target point included in the overlap sub-area is less than the candidate coefficient threshold, the overlap sub-area is eliminated (after eliminating the invalid overlap sub-area, the remaining is the effective overlap sub-area);

[0099] marking the overlap sub-area that is not eliminated as an effective overlap area, and marking the target point with the highest candidate coefficient in the effective overlap area as the to-be-deployed point.

[0100] It needs to be further explained that, in the specific implementation process, the process of determining the to-be-deployed point range, the narrowband ad hoc network constraint and the fitness function, and performing multi-hop link deployment optimization based on the particle swarm algorithm includes:

[0101] If there is no effective overlapping area, the non-overlapping area between the spatial slice of the node and the spatial slice of the next node is obtained, for example, the spatial slice coverage area of node A is (2000-2800m, 3000-3800m), and the spatial slice coverage area of node B is (3200-3500m, 3800-4200m), then the non-overlapping area between node A and node B is (2800-3200m, 3800-3800m), the coordinate point range covered by the spatial slice of the node and the next node and the non-overlapping area is marked as the to-be-deployed point range, and the constraint condition of the to-be-coded point is set (the communication coverage range of the to-be-deployed point closest to the node must have an overlapping area with the communication coverage range of the node; the communication coverage range of the to-be-deployed point closest to the next node must have an overlapping area with the communication coverage range of the next node; if there are multiple to-be-deployed points, the communication coverage range of the other to-be-deployed point closest to a certain to-be-deployed point must have an overlapping area with the communication coverage range of the certain to-be-deployed point; the to-be-deployed point must satisfy the slope ≤ 10°, no large obstacles (such as rocks, trees), and the ground bearing capacity ≥ 5kg (supporting a portable base station), a plurality of multi-hop link deployment schemes (the multi-hop link deployment scheme includes the propagation direction and coordinate point of each to-be-deployed point) are randomly generated based on the to-be-deployed point range and the constraint condition, the estimated path loss sum in the multi-hop link deployment scheme is obtained (for example, the multi-hop link deployment scheme is node A→to-be-deployed node B→to-be-deployed node C→next node D, the estimated path loss between AB, BC and CD is obtained, the estimated path loss between AB, BC and CD is accumulated, and the estimated path loss sum is obtained), the total link distance (for example, the multi-hop link deployment scheme is node A→to-be-deployed node B→to-be-deployed node C→next node D, the three-dimensional straight line distance between AB, BC and CD is obtained, the three-dimensional straight line distance between AB, BC and CD is accumulated, and the total link distance is obtained), and the total energy consumption (the sum of the energy consumptions of each to-be-deployed point, the more to-be-deployed points, the higher the total energy consumption), a fitness function is constructed based on the estimated path loss sum, the total link distance and the total energy consumption, and the best multi-hop link deployment scheme is obtained based on the multi-hop link deployment scheme and the fitness function through a multi-objective genetic algorithm.

[0102] It needs to be further explained that in the specific implementation process, the fitness function is specifically:

[0103] ;

[0104] wherein, , , represents the weight coefficient, represents the estimated path loss sum, represents the maximum theoretical path loss sum, is the total link distance, represents the theoretical maximum total link distance, represents the total energy consumption, represents the theoretical maximum total energy consumption; the above formulas are dimensionless values calculated, the formula is obtained by collecting a large amount of data to simulate the closest real situation, and the preset parameters in the formula are set by the person skilled in the art according to the actual situation or obtained by a large amount of data simulation.

[0105] It needs to be further explained that in the specific implementation process, the specific process of obtaining the best multi-hop link deployment scheme by the multi-objective genetic algorithm includes:

[0106] The multi-hop link deployment scheme is taken as a chromosome, for example, a string of numbers representing the coordinate points of the nodes to be deployed and other information. A certain number of chromosomes are randomly generated to form an initial population, the fitness function of each chromosome is obtained, the lower fitness chromosomes in the current population are selected as the parent generation by the tournament selection method, the parent chromosome is crossed to exchange part of the genes, and the new child chromosome is generated. Simulate biological genetic gene exchange to produce a new production plan scheme. The child chromosome is mutated to randomly change part of the genes, increase the diversity of the population, avoid falling into local optimum, repeat the above steps, and iterate until the termination condition is met, such as reaching the maximum number of iterations or the fitness value no longer obviously decreases, and output the best multi-hop link deployment scheme.

[0107] It needs to be further explained that in the specific implementation process, the process of implementing the deployment based on the best multi-hop link deployment scheme includes:

[0108] The best multi-hop link deployment scheme is sent to the user end, the user end deploys the narrowband talkback ad hoc network base station equipment according to the coordinate points of the nodes to be deployed in the best multi-hop link deployment scheme, and marks the deployed narrowband as a node. Based on the coordinate points of the nodes to be deployed, the deployed narrowband talkback ad hoc network base station equipment is inserted into the directional topology graph. For example: the coordinate points of the nodes to be deployed are sent to the mobile terminal of the on-site personnel, and the mobile application will display these information and provide real-time navigation and visual prompts to guide the user to go to the recommended deployment location. This mobile guidance enables the user to quickly and automatically deploy multiple ad hoc network devices according to the specific terrain, ensures that the links between the devices are established in the optimal configuration, and thus guarantees the performance.

[0109] It needs to be further explained that in the specific implementation process, the process of monitoring the link quality and dynamically adjusting the link deployment according to the monitoring results includes:

[0110] Each node in the directional topology map periodically (every 30s) sends a detection data packet to the adjacent node, the detection data packet includes effective radiation power, transmitting antenna gain and transmitting cable loss, the adjacent node obtains the signal strength of the received detection data packet, and the path loss is obtained according to the effective radiation power, the transmitting antenna gain, the transmitting cable loss and the signal strength (path loss = effective radiation power + transmitting antenna gain - transmitting cable loss - signal strength);

[0111] The estimated path loss between the node and the adjacent node is obtained, the path loss between the node and the adjacent node is compared with the estimated path loss, the path loss deviation is obtained, the path loss deviation is compared with the preset path loss error threshold, if the path loss deviation is greater than the path loss error threshold, step s3 is performed for the node and the adjacent node, that is, whether there is an effective overlapping area between the node and the adjacent node in the directional topology map is determined, if there is an effective overlapping area, the to-be-deployed point is re-obtained based on the estimated path loss, if there is no effective overlapping area, the to-be-deployed point range, the narrowband ad hoc network constraint and the fitness function are determined, the multi-hop link deployment optimization is performed based on the particle swarm algorithm, and the best multi-hop link deployment scheme is re-output.

[0112] The above embodiments are only used to illustrate the technical method of the present application and are not limited. Although the present application is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical method of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical method of the present application.

Claims

1. A method for optimized deployment of multi-hop links in narrowband self-organizing networks with three-dimensional propagation modeling, characterized in that, The method comprises the following steps: Step s1: constructing a three-dimensional space view of the deployment area, and constructing a direction topology graph based on the accurate position information and propagation direction of the deployed narrowband intercom ad hoc network base station device; Step s2: performing propagation path type division and propagation path loss estimation on each node in the direction topology graph based on the three-dimensional space view, and obtaining the estimated path loss of each node to a target point; Step s3: determining whether there is an overlapping sub-area between the space slice of the node and the space slice of the next node in the direction topology graph, if there is an overlapping sub-area, obtaining the estimated path loss and the three-dimensional space straight-line distance between each target point and the node and the next node respectively contained in the overlapping sub-area, adding the estimated path loss between each target point and the node and the next node respectively to obtain the total estimated path loss of each target point, and adding the three-dimensional space straight-line distance between each target point and the node and the next node respectively to obtain the total link distance; performing terrain condition screening on each target point, eliminating target points that do not meet the terrain condition, then performing weighted average on the total estimated path loss and the total link distance of each target point to obtain a candidate coefficient of each target point, comparing the candidate coefficient of each target point with a preset candidate coefficient threshold, if the candidate coefficient of each target point contained in the overlapping sub-area is less than the candidate coefficient threshold, the overlapping sub-area is eliminated; marking the overlapping sub-area that is not eliminated as an effective overlapping area, and marking the target point with the highest candidate coefficient in the effective overlapping area as a to-be-deployed point; if there is no effective overlapping area, determining the to-be-deployed point range, the narrowband ad hoc network constraint and the fitness function, performing multi-hop link deployment optimization based on a particle swarm algorithm, and outputting an optimal multi-hop link deployment scheme; Step s4: implementing deployment based on the optimal multi-hop link deployment scheme, and performing link quality monitoring, and dynamically adjusting the link deployment according to the monitoring result.

2. The method of claim 1, wherein the method further comprises: The process of constructing the three-dimensional space view of the deployment area comprises: obtaining GIS terrain data, laser radar building data and vegetation data of the deployment area; constructing a space coordinate system of the deployment area, extracting the elevation value of each coordinate point in the space coordinate system from the GIS terrain data to construct a terrain elevation layer, extracting the vertex coordinates, wall contour and material label of each building from the laser radar building data to construct a building layer, and extracting the coverage range and height of the vegetation from the vegetation data to construct a vegetation coverage layer; taking the terrain elevation layer as a base layer, superimposing the building layer and the vegetation coverage layer on the terrain elevation layer to obtain the three-dimensional space view.

3. The method of claim 2, wherein the method further comprises: The process of constructing the direction topology graph comprises: obtaining the accurate position information of each narrowband intercom ad hoc network base station device that has been deployed in the three-dimensional space view, and the source base station device and the target base station device in the narrowband intercom ad hoc network base station device, obtaining the propagation direction according to the source base station device and the target base station device, marking each narrowband intercom ad hoc network base station device as a node, and constructing the direction topology graph according to the accurate position information and the propagation direction of each node.

4. The method of claim 3, wherein the method further comprises: The process of performing propagation path type division comprises: Obtain the narrowband signal operating frequency and communication coverage range of each node, divide the spatial slice of each node in a three-dimensional space view according to the communication coverage range, perform gridding processing on the spatial slice, and divide the spatial slice into a plurality of sub-regions; Obtain a three-dimensional straight line from the node to any target point in the spatial slice of the node, obtain the altitude value of each sampling point on the three-dimensional straight line and the altitude value of each sampling point in the spatial slice, and compare the altitude value of each sampling point on the three-dimensional straight line with the altitude value of each sampling point in the spatial slice; If the altitude value of each sampling point is greater than the altitude value of each sampling point in the spatial slice, the three-dimensional straight line is marked as a line-of-sight link, and if there is a sampling point whose altitude value is less than the altitude value of the sampling point in the spatial slice, the sampling point is marked as an obstacle sampling point, and the three-dimensional straight line is marked as a non-line-of-sight link.

5. The method of claim 4, wherein the method further comprises: The process of performing propagation path loss estimation includes: When the three-dimensional straight line from the node to the target point is a line-of-sight link, the estimated path loss from the node to the target point is obtained according to the three-dimensional space straight line distance between the node and the target point and the narrowband signal operating frequency of the node.

6. The method of claim 5, wherein the method further comprises: The process of performing propagation path loss estimation includes: When the three-dimensional straight line from the node to the target point is a non-line-of-sight link, the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is obtained, the obstacle range is identified, the obstacle range is divided into a reflecting surface, a sharp edge or an invalid obstacle; If the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is an invalid obstacle, the estimated path loss from the node to the target point is obtained according to the three-dimensional space straight line distance between the node and the target point and the narrowband signal operating frequency of the node; If the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is a reflecting surface, the material attenuation coefficient of the reflecting surface is obtained, and the estimated path loss from the node to the target point is obtained according to the three-dimensional space straight line distance between the node and the target point, the narrowband signal operating frequency of the node and the material attenuation coefficient; If the obstacle range to which the obstacle sampling point in the three-dimensional straight line belongs is a sharp edge, the altitude value maximum point of the sharp edge is selected as a diffraction vertex, the perpendicular distance from the diffraction vertex to the three-dimensional straight line and the three-dimensional space straight line distances from the diffraction vertex to the node and the target point are obtained, and the estimated path loss from the node to the target point is obtained based on the narrowband signal operating frequency of the node, the perpendicular distance and the three-dimensional space straight line distances from the diffraction vertex to the node and the target point.

7. The method of claim 6, wherein the method further comprises: The process of determining the to-be-deployed node range, the narrowband ad hoc network constraint and the fitness function, and performing multi-hop link deployment optimization based on a particle swarm algorithm includes: If there is no effective overlapping area, an area without overlapping between the spatial slice of the node and the spatial slice of the next node is obtained, the spatial slice of the node and the next node and the coordinate point range covered by the area without overlapping are marked as a to-be-deployed point range, a constraint condition of a to-be-coded point is set, a plurality of multi-hop link deployment schemes are randomly generated based on the to-be-deployed point range and the constraint condition, an estimated path loss sum, a total link distance and a total energy consumption in the multi-hop link deployment schemes are obtained, an adaptive function is constructed based on the estimated path loss sum, the total link distance and the total energy consumption, and the best multi-hop link deployment scheme is obtained through a multi-objective genetic algorithm based on the multi-hop link deployment schemes and the adaptive function.

8. The method of claim 7, wherein the method further comprises: The process of implementing deployment based on the best multi-hop link deployment scheme includes: The best multi-hop link deployment scheme is sent to the user end, the user end deploys the narrowband talkback ad hoc network base station equipment according to the coordinate point of the to-be-deployed point in the best multi-hop link deployment scheme, and marks the deployed narrowband as a node, and inserts the deployed narrowband talkback ad hoc network base station equipment into the directional topology graph.

9. The method of claim 8, wherein the method further comprises: The process of link quality monitoring and dynamic adjustment of link deployment according to the monitoring result includes: Each node in the directional topology graph periodically sends a detection data packet to the adjacent node, the detection data packet includes effective radiation power, transmission antenna gain and transmission cable loss, the adjacent node obtains the signal strength of the received detection data packet, and the path loss is obtained according to the effective radiation power, the transmission antenna gain, the transmission cable loss and the signal strength; The estimated path loss between the node and the adjacent node is obtained, the path loss between the node and the adjacent node is compared with the estimated path loss, the path loss deviation is obtained, the path loss deviation is compared with a preset path loss error threshold, and if the path loss deviation is greater than the path loss error threshold, step s3 is performed for the node and the adjacent node.

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