Cell handover methods and devices for network-connected drones, and communication systems

Abstract

This application discloses a cell handover method, apparatus, and communication system for connected drones. It includes: acquiring a measurement report from the connected drone within a target time period; determining the target extended PCI to which the connected drone will handover will be based on the measurement report; matching the target extended PCI with a preset base station mapping table to determine the target base station corresponding to the target extended PCI, and determining the target path to the target base station from a preset target path table; and handing the connected drone to the target cell covered by the target base station according to the target path. This application solves the technical problem that existing network base stations do not support handover of connected drones in cells without configured neighbor cell relationships.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and more specifically, to a cell handover method and apparatus for networked unmanned aerial vehicles (UAVs) and a communication system. Background Technology

[0002] Currently, 5G networks primarily provide ground coverage, and building new dedicated airspace networks is costly. Therefore, ensuring the quality of both high-altitude and large-scale 5G networks while using existing sites is the biggest challenge in airspace networking.

[0003] Typically, the neighbor cell configuration of a terrestrial network is determined by the handover relationships of terrestrial users. Testing and analysis show that the airspace usually receives more than 10 signals, primarily from signal reflections from the main terrestrial network. However, due to the long coverage area of ​​base stations in the airspace, terminals within the current serving cell may receive signals from multiple neighboring cells with the same PCI (Physical Cell Identity). Since the terrestrial network's neighbor cell configuration based on the handover relationships of terrestrial users is generally only one, applying traditional handover and PCI reuse rules based on terrestrial network neighbor cell relationships in low-altitude networks can cause terminals within the current serving cell to handover to the wrong neighboring cell based on these relationships, leading to terminal access failure.

[0004] There is currently no effective solution to the above problems. Summary of the Invention

[0005] This application provides a cell handover method, apparatus, and communication system for connected drones, to at least solve the technical problem that existing base stations do not support connected drones handover in cells without configured neighbor cell relationships.

[0006] According to one aspect of the embodiments of this application, a cell handover method for a network-connected drone is provided, comprising: acquiring a measurement report of the network-connected drone within a target time period; determining the target extended physical cell identifier (PCI) to which the network-connected drone is to be handed over to based on the measurement report, wherein the target extended PCI consists of the PCI of the target cell and the group number of the idle subcarrier group corresponding to the target cell; matching the target extended PCI with a preset base station mapping table to determine the target base station corresponding to the target extended PCI, and determining the target path to the target base station from a preset target path table, wherein the base station mapping table includes mapping relationships between multiple groups of extended PCIs and base stations within the low-altitude network coverage area, and the target path table includes paths within the low-altitude network coverage area where the handover delay of multiple base stations within the target time period is less than a preset threshold; and handing the network-connected drone over to the target cell covered by the target base station according to the target path.

[0007] Optionally, before obtaining the measurement report of the connected drone within the target time period, the method further includes: receiving a registration request message from the connected drone, wherein the registration request message includes at least: registration type, identity identifier, last accessed tracking area identifier, and requested network slice selection auxiliary information; and allocating a dedicated network slice to the connected drone based on the registration request message.

[0008] Optionally, the construction process of the base station mapping table includes: obtaining the base station identifiers of all base stations within the low-altitude network coverage area and the PCI of each cell covered by each base station; for each base station, determining the first number of subcarriers of the first orthogonal frequency division multiplexing (OFDM) signal of the physical broadcast channel of the base station and the second number of subcarriers used for signal transmission within the first number of subcarriers, wherein the first OFDM signal is used to carry the primary synchronization signal; determining the third number of subcarriers not used for signal transmission based on the first and second numbers; grouping the third number of subcarriers according to a preset number of carriers to obtain multiple groups of subcarriers and determining the group number of each group of subcarriers; forming the extended PCI of each cell covered by the base station by the PCI of each cell and the group number of the subcarrier group to which at least one subcarrier of each cell belongs; summarizing the mapping relationship between the base station identifiers of each base station and the extended PCI of each cell covered by the base station to obtain the base station mapping table.

[0009] Optionally, the PCI of each cell covered by all base stations within the low-altitude network coverage area is obtained, including: determining all base stations within the low-altitude network coverage area; traversing each base station, using the current base station as the origin and a preset distance or preset site level as the radius, constructing a Delaunay triangulation network using the Delaunay triangulation algorithm, and obtaining the PCI of each cell within the Delaunay triangulation network.

[0010] Optionally, the process of constructing the target path table includes: obtaining the time delay between each base station within the low-altitude network coverage area during the target time period; constructing a weighted graph of the low-altitude network coverage area using each base station as a graph node, the handover relationship between each base station as an edge, and the time delay between each base station as the edge weight; and analyzing the weighted graph using the Dijkstra algorithm to obtain paths where the handover time delay between each base station is less than a preset threshold, thus forming the target path table.

[0011] Optionally, the connected drone is switched to the target cell covered by the target base station according to the target path, including: determining all intermediate base stations in the target path and the access sequence number of each intermediate base station; and sequentially connecting the connected drone to each intermediate base station according to the access sequence number of each intermediate base station until it is switched to the target cell covered by the target base station.

[0012] Optionally, after switching the connected drone to the target cell covered by the target base station according to the target path, the method further includes: releasing the radio resources corresponding to the network slice allocated to the connected drone.

[0013] According to another aspect of the embodiments of this application, a cell handover device for a network-connected drone is also provided, comprising: an acquisition module, configured to acquire a measurement report of the network-connected drone within a target time period; a first determination module, configured to determine the target extended PCI to which the network-connected drone is to be handed over to the target cell based on the measurement report, wherein the target extended PCI consists of the PCI of the target cell and the group number of the idle subcarrier group corresponding to the target cell; a second determination module, configured to match the target extended PCI with a preset base station mapping table to determine the target base station corresponding to the target extended PCI, and determine the target path to the target base station by a preset target path table, wherein the base station mapping table includes multiple sets of extended PCIs and mapping relationships between base stations within the low-altitude network coverage area, and the target path table includes: paths within the low-altitude network coverage area where the handover delay of multiple base stations within the target time period is less than a preset threshold; and a handover module, configured to handover the network-connected drone to the target cell covered by the target base station according to the target path.

[0014] According to another aspect of the embodiments of this application, a communication system is also provided. The system includes: a network-connected drone and network equipment, wherein the network equipment includes: a source base station and a target base station. The network-connected drone is used to report measurement reports within a target time period to the source base station. The source base station is used to acquire the measurement reports of the network-connected drone within the target time period. Based on the measurement reports, the system determines the target extended physical cell identifier (PCI) to which the network-connected drone will be handed over to the target cell. The target extended PCI consists of the PCI of the target cell and the group number of the idle subcarrier group corresponding to the target cell. The system matches the target extended PCI with a preset base station mapping table to determine the target base station corresponding to the target extended PCI, and determines the target path to the target base station using a preset target path table. The base station mapping table includes multiple sets of extended PCIs and mapping relationships between base stations within the low-altitude network coverage area. The target path table includes paths within the low-altitude network coverage area where the handover delay of multiple base stations within the target time period is less than a preset threshold. The system then hands over the network-connected drone to the target cell covered by the target base station according to the target path.

[0015] According to another aspect of the embodiments of this application, a network device is also provided, the network device including: a memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the above-described cell handover method for networked drones through the computer program.

[0016] In this embodiment, a measurement report of the connected drone within a target time period is obtained; based on the measurement report, the target extended physical cell identifier (PCI) to which the connected drone is to be handed over is determined, wherein the target extended PCI consists of the PCI of the target cell and the group number of the idle subcarrier group corresponding to the target cell; the target extended PCI is matched with a preset base station mapping table to determine the target base station corresponding to the target extended PCI, and a preset target path table is used to determine the target path to the target base station, wherein the base station mapping table includes the mapping relationship between multiple groups of extended PCIs and base stations within the low-altitude network coverage area, and the target path table includes: paths where the handover delay of multiple base stations within the low-altitude network coverage area is less than a preset threshold within the target time period; the connected drone is handed over to the target cell covered by the target base station according to the target path, thereby solving the technical problem that the current network base station does not support the handover of connected drones in cells without configured neighbor cell relationships. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 This is a schematic diagram of the architecture of an optional communication system according to an embodiment of this application;

[0019] Figure 2 This is a hardware structure block diagram of a computer terminal (or mobile device) for implementing a cell handover method for a networked drone, according to an embodiment of this application.

[0020] Figure 3 This is a flowchart illustrating an optional cell handover method for a networked drone according to an embodiment of this application.

[0021] Figure 4 This is a schematic diagram of an optional subcarrier partitioning method according to an embodiment of this application;

[0022] Figure 5 This is a schematic diagram of an optional claimed diagram according to an embodiment of this application;

[0023] Figure 6 This is a schematic diagram of the structure of an optional cell handover device for a networked drone according to an embodiment of this application;

[0024] Figure 7 This is a schematic diagram of the structure of an optional network device according to an embodiment of this application. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] Furthermore, all information and data (including but not limited to user device information, user personal information, etc.) involved in this application are information and data authorized by the user or fully authorized by all parties. For example, this system has an interface with the relevant user or organization. Before obtaining relevant information, it needs to send an acquisition request to the aforementioned user or organization through the interface, and obtain the relevant information after receiving consent from the aforementioned user or organization.

[0028] To better understand the embodiments of this application, the technical terms involved in the embodiments of this application are explained below:

[0029] Network Slice Selection Assistance Information (NSSI) is a parameter used in 5G networks to identify network slices. It includes the SST (Slice / Service Type) field and the SD (Slice Differentiator) field. The SST field indicates the slice / service type, while the SD field is used to further distinguish different slice instances under the same SST value. Therefore, NSSI uses information about slices transmitted in signaling messages between user equipment and the network to assist the network in selecting appropriate network slices according to the needs of the UE and network policies.

[0030] Example 1

[0031] Under the current site address, the neighbor cell configuration of the terrestrial network is usually set according to the handover needs of terrestrial users. The common practice is to configure multiple base stations (generally no more than three layers of sites) for the site service area to ensure that there is an overlapping coverage relationship between them.

[0032] However, within the airspace network, due to the wide coverage area (which can cover multiple base stations), connected drones within the airspace will receive signals reflected from multiple ground network signals. However, because the ground stations are far apart and have a wide coverage area and strong transmission signals (because there is less obstruction in the airspace), and because some of the signals received by the connected drones have no neighboring cell relationship with the serving cell covered by the current source base station, connected drones cannot directly switch cells based on the signal, which seriously affects the perception of airspace users.

[0033] Furthermore, because low-altitude networks have a long coverage area, and the Physical Cell Identifier (PCI) rules configured for cells within the range of each existing base station are the same, low-altitude networks cannot directly use the PCI rules planned for terrestrial networks. For example, if a connected drone receives signals from three cells with a PCI of 4 in its current serving cell, but the base station of the current serving cell only has one neighboring cell with a PCI of 4, the drone may be switched to the wrong cell based on the neighboring cell relationship, resulting in service discontinuity.

[0034] To address the problems existing in the above-mentioned technologies, relevant solutions are provided in the embodiments of this application, which are described in detail below.

[0035] According to the embodiments of this application, a method embodiment for cell handover of a network-connected drone is provided. The technical solution of this application embodiment can be applied to various communication systems, such as: Global System of Mobile communication (GSM) system, Code Division Multiple Access (CDMA) system, Wideband Code Division Multiple Access (WCDMA) system, General Packet Radio Service (GPRS), Long Term Evolution (LTE) system, LTE Frequency Division Duplex (FDD) system, LTE Time Division Duplex (TDD) system, Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) communication system, or 5G system, etc.

[0036] For example, the architecture of the communication system 100 used in the embodiments of this application is as follows: Figure 1 As shown. The communication system 100 may include a network device 110, and the network device 110 includes a source base station and a target base station, both of which can communicate with the terminal device 120 (or a communication terminal, terminal).

[0037] Specifically, network device 110 can provide communication coverage for a specific geographical area and communicate with terminal devices located within that coverage area. Optionally, network device 110 can be a base station (BTS) in a GSM or CDMA system, a base station (NodeB, NB) in a WCDMA system, an evolved Node B (eNB or eNodeB) in an LTE system, or a radio controller in a Cloud Radio Access Network (CRAN). Alternatively, the network device can be a mobile switching center, relay station, access point, vehicle-mounted equipment, wearable device, hub, switch, bridge, router, network-side equipment in a 5G network, or network equipment in a future evolved Public Land Mobile Network (PLMN), etc.

[0038] The communication system 100 also includes at least one terminal device 120 located within the coverage area of ​​the network device 110. As used herein, a "terminal device" may be a network-connected drone. Optionally, the terminal devices 120 may perform device-to-device (D2D) communication with each other.

[0039] Furthermore, it should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0040] The method embodiments provided in this application can be executed in a mobile terminal, computer terminal, or similar computing device within the source base station. Figure 2 A hardware block diagram of a computer terminal (or mobile device) for implementing a cell handover method for connected drones is shown. Figure 2 As shown, the computer terminal 20 (or mobile device 20) may include one or more processors 202 (shown as 202a, 202b, ..., 202n in the figure) 202 (processor 202 may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.), a memory 204 for storing data, and a transmission device 206 for communication functions. In addition, it may also include: a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which may be included as one of the ports of a BUS bus), a network interface, a power supply, and / or a camera. Those skilled in the art will understand that... Figure 2The structure shown is for illustrative purposes only and does not limit the structure of the aforementioned electronic device. For example, computer terminal 20 may also include... Figure 2 The more or fewer components shown, or having the same Figure 2 The different configurations shown.

[0041] It should be noted that the aforementioned one or more processors 202 and / or other data processing circuits are generally referred to herein as "data processing circuits". These data processing circuits may be embodied, in whole or in part, in software, hardware, firmware, or any other combination thereof. Furthermore, the data processing circuits may be a single, independent processing module, or may be integrated, in whole or in part, into any other element within the computer terminal 20 (or mobile device). As involved in the embodiments of this application, the data processing circuits serve as a processor control mechanism (e.g., selection of a variable resistor termination path connected to an interface).

[0042] The memory 204 can be used to store software programs and modules of application software, such as the program instructions / data storage device corresponding to the cell handover method for the networked drone in this embodiment of the application. The processor 202 executes various functional applications and data processing by running the software programs and modules stored in the memory 204, thereby implementing the aforementioned cell handover method for the networked drone application. The memory 204 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 204 may further include memory remotely located relative to the processor 202, and these remote memories can be connected to the computer terminal 20 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0043] The transmission device 206 is used to receive or send data via a network. Specific examples of the network described above may include a wireless network provided by the communication provider of the computer terminal 20. In one example, the transmission device 206 includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device 206 may be a Radio Frequency (RF) module, used for wireless communication with the Internet.

[0044] The display may be, for example, a touchscreen liquid crystal display (LCD) that allows the user to interact with the user interface of the computer terminal 20 (or mobile device).

[0045] Under the above operating environment, Figure 3This is a flowchart illustrating an optional cell handover method for a networked drone according to an embodiment of this application, as shown below. Figure 3 As shown, the method includes at least steps S302-S306, wherein:

[0046] Step S302: Obtain the measurement report of the connected drone within the target time period.

[0047] In the technical solution provided in step S302, the Measurement Report (MR) is important information about signal quality reported by the user equipment to the network, such as RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), RSSI (Received Signal Strength Indicator), and neighbor cell measurements. These measurement reports can be periodically reported to the source base station by a network-connected drone (the periodic interval equals the target time period), or triggered by a specific event (the time interval between the last report and the current report equals the target time period).

[0048] Step S304: Determine the target extended physical cell identifier (PCI) to which the connected drone is to be switched to based on the measurement report.

[0049] In the technical solution provided in step S304, after receiving the measurement report reported by the networked drone, the source base station determines the optimal target cell for handover based on the information in the report, such as the signal quality of the cell, the signal quality of the currently serving cell, and other factors that may affect the decision, such as cell load and inter-cell handover protocols. Since low-altitude networks cannot directly use the PCI rules planned for terrestrial networks, this embodiment uses a target extended PCI composed of the target cell's PCI and the group number of the idle subcarrier group corresponding to the target cell. This is because each base station has a different number of subcarriers allocated, different subcarriers defined for transmitting energy, and different numbers of subcarriers configured for each cell under the base station's coverage. Therefore, the target cell's PCI and the group number of the idle subcarrier group corresponding to the target cell can be used together as the cell's physical identifier.

[0050] Step S306: Match the target extended PCI with the preset base station mapping table to determine the target base station corresponding to the target extended PCI, and determine the target path to the target base station by using the preset target path table.

[0051] In the technical solution provided in step S306, the base station mapping table includes multiple sets of mapping relationships between extended PCIs and base stations within the low-altitude network coverage area. Therefore, the source base station can match the target extended PCI determined in step S406 with the base station mapping table to determine the target base station corresponding to the target extended PCI. Then, it determines the target path from the source base station to the target base station according to a pre-defined target path table. This target path table includes paths where the handover latency of multiple base stations within the low-altitude network coverage area is less than a preset threshold (i.e., the shortest latency) within a target time period. Therefore, the determined target path can ensure the handover latency of low-altitude services in application scenarios with high real-time requirements.

[0052] Step S308: Switch the connected drone to the target cell covered by the target base station according to the target path.

[0053] The method described in this embodiment will be further described below.

[0054] As an optional implementation, before obtaining the measurement report of the connected drone within the target time period, the source base station may also conduct online detection of the connected drone according to the following method:

[0055] Step 1: The source base station receives the registration request message from the connected drone. The registration request message includes at least the following: Registration Type, identity identifier (such as subscriber permanent identifier SUCI, globally unique temporary identifier GUTI, permanent device identifier PEI, etc.), tracking area identity (TAI, used to identify the tracking area where the mobile device is located) and network slice selection assistance information NSSI (used to help the network understand the type of network slice it wants to access and select the appropriate access and mobility management function (AMF) network and related network slice instance accordingly).

[0056] Step 2: Assign a dedicated network slice to the connected drone based on the registration request message.

[0057] Among them, the source base station allocates a dedicated network slice to the connected drone to provide wireless resources that meet its needs.

[0058] As an optional implementation, in the technical solution provided in step S406 above, the process of constructing the base station mapping table of the low-altitude network may include the following steps:

[0059] Step 1: Obtain the base station identifiers of all base stations within the low-altitude network coverage area, as well as the PCI of each cell covered by each base station.

[0060] Specifically, the base station identifiers and PCIs of each cell covered by the aforementioned base stations are pre-configured during network deployment. Therefore, given the large coverage area of ​​low-altitude networks, this application proposes the following method to accurately obtain the PCIs of all cells covered by the base stations:

[0061] First, identify all base stations within the low-altitude network coverage area.

[0062] Then, each base station is traversed sequentially. Taking the current base station as the origin and a preset distance (e.g., 10KM from the current station) or a preset station level (e.g., 5 stations around the current station) as the radius, a Delaunay triangulation algorithm is used to construct a Delaunay triangulation network and obtain the PCI of each cell within the Delaunay triangulation network.

[0063] The criteria used in the Delaunay triangulation algorithm can be any one of the following: the minimum interior angle maximum criterion, the maximum subtended angle criterion, the empty circumcircle criterion, and the maximum circumcircle minimum criterion.

[0064] Step 2: The first OFDM symbol of the physical broadcast channel (PBCH) of the base station is used to carry the PSS (Primary Synchronization Signal). The number of subcarriers corresponding to it can be set according to the system bandwidth and subcarrier spacing (such as 15kHz, 30kHz, 60kHz, 120kHz and 240kHz). Different cells covered by the base station can use different bandwidth parts (BWP), and each BWP can have different subcarrier spacing and bandwidth configuration. Therefore, the number of subcarriers used by each cell covered by the base station is also different.

[0065] Therefore, for each base station, the following steps can be performed cyclically to determine the extended PCI of each cell covered by the base station:

[0066] First, determine the first number of subcarriers of the first orthogonal frequency division multiplexing signal of the physical broadcast channel of the base station and the second number of subcarriers used for transmitting signals within the first number of subcarriers, wherein the first orthogonal frequency division multiplexing signal is used to carry the main synchronization signal;

[0067] Then, based on the first and second quantities, a third quantity of subcarriers not used for signal transmission is determined; the third quantity of subcarriers is grouped according to the preset number of carriers to obtain multiple groups of subcarriers, and the group number of each group of subcarriers is determined.

[0068] Finally, the extended PCI of each cell covered by the base station is composed of the PCI of each cell and the group number of the subcarrier group to which at least one subcarrier of each cell belongs.

[0069] For example, the first OFDM symbol of the physical broadcast channel configured by base station A corresponds to a first number of 240 subcarriers, and the sequence number of each subcarrier is 0-239. If the PSS uses the middle 120 subcarriers (i.e., the second number) of the first OFDM symbol (i.e., subcarriers with sequence numbers 60-179), then the remaining 120 subcarriers not used for energy transmission (i.e., the third number) are subcarriers with sequence numbers 0-59 and 180-239. The remaining 120 subcarriers will be grouped into 8 groups of 15 subcarriers each (the preset number of carriers), resulting in 8 groups, such as... Figure 4 As shown, the group number of each subcarrier group is determined sequentially. For example, the group number of the subcarrier group containing subcarriers with serial numbers 0-14 is 1, the group number of the subcarrier group containing subcarriers with serial numbers 15-29 is 2, and so on. Since each cell within the base station coverage area is usually allocated one or more subcarriers, and in the case of multiple subcarriers, the subcarriers are usually consecutive, the group number of the corresponding subcarrier group can be determined based on the subcarrier group containing the serial number of at least one subcarrier corresponding to each cell. Then, the extended PCI of each cell covered by the base station and the group number of the subcarrier group containing at least one subcarrier corresponding to each cell are used to form the extended PCI of each cell covered by the base station.

[0070] Step 3: Summarize the mapping relationship between the base station identifier of each base station and the extended PCI of each cell covered by the base station to obtain the base station mapping table.

[0071] It should be noted that after obtaining the above base station mapping table, the base station mapping table can be stored locally on the source base station.

[0072] As an optional implementation, in the technical solution provided in step S406 above, since the handover paths between base stations within the low-altitude network coverage area have different latency periods at different times, the process of constructing the target path table for the low-altitude network coverage area within the target time period can include:

[0073] Step 1: Obtain the latency between each base station within the low-altitude network coverage area during the target time period.

[0074] The source base station can first obtain the latency between various base stations within the low-altitude network coverage area during the target time period through PING packets between base stations.

[0075] Step 2: Using each base station as a graph node, the handover relationship between each base station as an edge, and the latency between each base station as the edge weight, construct a weighted graph of the low-altitude network coverage area.

[0076] In this method, the source base station can use all base stations within the low-altitude network coverage area as graph nodes, the Xn interface between base stations as the path start and end points, and the transmission delay between base stations as the path length to construct a weighted graph. For example... Figure 5 An optional weighted graph is shown, where the numbers inside the circles are the base station numbers, and the numbers on the lines connecting the base stations represent the time delay.

[0077] Step 3: Use Dijkstra's algorithm to analyze the weighted graph, obtain the paths where the handover delay between each base station is less than a preset threshold, and form a target path table.

[0078] Specifically, for any two graph nodes within a weighted graph, with one node as the starting point and the other as the ending point, Dijkstra's algorithm is used to determine the paths with a time delay less than a preset threshold among multiple paths from the starting point to the ending point. Dijkstra's algorithm starts from the starting point and employs a greedy algorithm strategy, iterating through the nearest unvisited vertex's adjacent node each time until it extends to the ending point.

[0079] As an optional implementation, in the technical solution provided in step S306 above, the source base station can perform cell handover for the network-connected drone in the following manner: determining all intermediate base stations within the target path and the access sequence number of each intermediate base station; sequentially connecting the network-connected drone to each intermediate base station according to the access sequence number of each intermediate base station until it is switched to the target cell covered by the target base station.

[0080] In this embodiment, sequentially connecting the connected drone to each intermediate base station according to the access sequence number of each intermediate base station means that the cell handover request message initiated by the source base station is first sent to the first intermediate base station. After the first intermediate base station successfully responds to the request, it sends an access success response message back to the source base station and forwards the cell handover request message to the second intermediate base station. This process continues until the target base station sends an access success response message back to the previous intermediate base station. At this point, the connected drone switches to the target cell covered by the target base station.

[0081] Furthermore, after the source base station switches the connected drone to the target cell covered by the target base station according to the target path, the source base station can release the radio resources corresponding to the network slice allocated to the connected drone before the switch.

[0082] In addition, the source base station can forward unsent data to the target base station and update the node relationships in the user plane and control plane.

[0083] Based on the scheme defined in steps S302 to S306 above, it can be understood that, in this embodiment, the source base station determines the target extended PCI to which the connected drone should hand over to the target cell based on the measurement report of the connected drone within the target time period. To avoid the PCI reuse problem of traditional terrestrial networks, the blank subcarriers of the PSS signal in the PBCH can be used to group them, and the PCI of each cell can be marked through different carrier groups to construct the extended PCI, thereby greatly improving the accuracy of identifying the target cell. Furthermore, to improve the service transmission latency during handover, the target path with the lowest latency can be selected from multiple paths between the source base station and the target base station, so that the connected drone can be handed over to the target cell covered by the target base station according to the target path. This solves the technical problem that existing network base stations do not support handover of connected drones in cells without configured neighbor cell relationships.

[0084] Example 2

[0085] Based on Embodiment 1 of this application, an embodiment of a cell handover device for a network-connected drone is also provided. This device, when running, executes the cell handover method for a network-connected drone described in the above embodiment. Wherein, Figure 6 This is a schematic diagram of the structure of an optional cell handover device for a networked drone according to an embodiment of this application, as shown below. Figure 6 As shown, the cell handover device of the network-connected drone includes at least an acquisition module 62, a first determination module 64, a second determination module 66, and a handover module 68, wherein:

[0086] Module 62 is used to acquire measurement reports of the connected drone within the target time period;

[0087] The first determining module 64 is used to determine the target extended PCI of the network-connected UAV to be handed over to the target cell based on the measurement report. The target extended PCI consists of the PCI of the target cell and the group number of the idle subcarrier group corresponding to the target cell.

[0088] The second determining module 66 is used to match the target extended PCI with the preset base station mapping table, determine the target base station corresponding to the target extended PCI, and determine the target path to the target base station by the preset target path table. The base station mapping table includes multiple sets of mapping relationships between extended PCI and base stations within the low-altitude network coverage area, and the target path table includes: paths within the low-altitude network coverage area where the handover delay of multiple base stations within the target time period is less than a preset threshold.

[0089] The switching module 68 is used to switch the connected drone to the target cell covered by the target base station according to the target path.

[0090] It should be noted that the modules in the cell handover device of the above-mentioned connected drone can be program modules (such as a set of program instructions to implement a certain function) or hardware modules. For the latter, they can be in the following forms, but are not limited to these: each of the above modules is in the form of a processor, or the functions of each of the above modules are implemented by a processor.

[0091] Example 3

[0092] According to an embodiment of this application, a non-volatile storage medium is also provided, which stores a program, wherein when the program runs, it controls the device where the non-volatile storage medium is located to execute the cell handover method for the connected drone in Embodiment 1.

[0093] Optionally, the device containing the non-volatile storage medium executes the following steps by running the program: acquiring a measurement report of the connected drone within the target time period; determining the target extended physical cell identifier (PCI) to which the connected drone will be handed over to based on the measurement report, wherein the target extended PCI consists of the target cell's PCI and the group number of the idle subcarrier group corresponding to the target cell; matching the target extended PCI with a preset base station mapping table to determine the target base station corresponding to the target extended PCI, and determining the target path to the target base station from a preset target path table, wherein the base station mapping table includes the mapping relationship between multiple groups of extended PCIs and base stations within the low-altitude network coverage area, and the target path table includes: paths within the low-altitude network coverage area where the handover delay of multiple base stations within the target time period is less than a preset threshold; and handing the connected drone over to the target cell covered by the target base station according to the target path.

[0094] According to an embodiment of this application, a computer program product is also provided, which includes a stored computer program, wherein when the computer program is executed by a processor, it implements the cell handover method for networked drones in Embodiment 1.

[0095] Optionally, the computer program performs the following steps: acquiring a measurement report of the connected drone within a target time period; determining the target extended physical cell identifier (PCI) to which the connected drone will be switched to based on the measurement report, wherein the target extended PCI consists of the target cell's PCI and the group number of the idle subcarrier group corresponding to the target cell; matching the target extended PCI with a preset base station mapping table to determine the target base station corresponding to the target extended PCI, and determining the target path to the target base station from a preset target path table, wherein the base station mapping table includes the mapping relationship between multiple groups of extended PCIs and base stations within the low-altitude network coverage area, and the target path table includes: paths where the switching delay of multiple base stations within the low-altitude network coverage area is less than a preset threshold within the target time period; and switching the connected drone to the target cell covered by the target base station according to the target path.

[0096] According to an embodiment of this application, a processor is also provided for running a program, wherein the program executes the cell handover method for networked drones in Embodiment 1 during runtime.

[0097] Optionally, the program executes the following steps during runtime: obtaining the measurement report of the connected drone within the target time period; determining the target extended physical cell identifier (PCI) to which the connected drone should be handed over to based on the measurement report, wherein the target extended PCI consists of the PCI of the target cell and the group number of the idle subcarrier group corresponding to the target cell; matching the target extended PCI with a preset base station mapping table to determine the target base station corresponding to the target extended PCI, and determining the target path to the target base station from a preset target path table, wherein the base station mapping table includes the mapping relationship between multiple groups of extended PCIs and base stations within the low-altitude network coverage area, and the target path table includes: paths where the handover delay of multiple base stations within the low-altitude network coverage area is less than a preset threshold within the target time period; and handing the connected drone over to the target cell covered by the target base station according to the target path.

[0098] According to an embodiment of this application, a network device is also provided, wherein... Figure 7 This is a schematic diagram of the structure of an optional network device according to an embodiment of this application, such as... Figure 7 As shown, the network device includes one or more processors; a memory for storing one or more programs, which, when executed by one or more processors, enable the one or more processors to run the programs, wherein the programs are configured to execute the cell handover method for the networked drone in Embodiment 1 above.

[0099] Optionally, the processor is configured to execute the following steps via a computer program: acquiring a measurement report of the connected drone within a target time period; determining the target extended physical cell identifier (PCI) to which the connected drone will be handed over to based on the measurement report, wherein the target extended PCI consists of the target cell's PCI and the group number of the idle subcarrier group corresponding to the target cell; matching the target extended PCI with a preset base station mapping table to determine the target base station corresponding to the target extended PCI, and determining the target path to the target base station using a preset target path table, wherein the base station mapping table includes mapping relationships between multiple groups of extended PCIs and base stations within the low-altitude network coverage area, and the target path table includes paths where the handover delay of multiple base stations within the low-altitude network coverage area is less than a preset threshold within the target time period; and handing the connected drone over to the target cell covered by the target base station according to the target path.

[0100] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0101] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0102] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between units or modules may be electrical or other forms.

[0103] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0104] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0105] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to related technologies, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard drive, magnetic disk, or optical disk.

[0106] The above are merely preferred embodiments of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A cell handover method for a network-connected drone, characterized in that, The method comprises: obtaining a measurement report of the network-connected UAV in a target time period; determining a target extended physical cell identifier (PCI) to which the network-connected UAV is to be handed over to a target cell according to the measurement report, wherein the target extended PCI is composed of a PCI of the target cell and a group number of an idle subcarrier group corresponding to the target cell; matching the target extended PCI with a preset base station mapping table to determine a target base station corresponding to the target extended PCI, and determining a target path to the target base station according to a preset target path table, wherein the base station mapping table comprises a mapping relationship between a plurality of extended PCIs and a plurality of base stations in a low-altitude network coverage range, and the target path table comprises a path of the plurality of base stations in the low-altitude network coverage range, the path having a time delay less than a preset threshold in the target time period; handing over the network-connected UAV to a target cell covered by the target base station according to the target path.

2. The method of claim 1, wherein, Before obtaining the measurement report of the network-connected UAV in the target time period, the method further comprises: receiving a registration request message of the network-connected UAV, wherein the registration request message at least comprises a registration type, an identity, a last visited tracking area identifier, and requested network slice selection assistance information; allocating a dedicated network slice to the network-connected UAV according to the registration request message.

3. The method of claim 1, wherein, The construction process of the base station mapping table comprises: obtaining base station identifiers of all base stations in the low-altitude network coverage range and PCIs of all cells covered by each base station; for each base station, determining a first number of subcarriers of a first orthogonal frequency division multiplexing signal of a physical broadcast channel of the base station and a second number of subcarriers used for transmitting signals in the first number of subcarriers, wherein the first orthogonal frequency division multiplexing signal is used to carry a primary synchronization signal; determining a third number of subcarriers not used for transmitting signals according to the first number and the second number; grouping the third number of subcarriers according to a preset carrier number to obtain a plurality of subcarrier groups, and determining group numbers of the subcarrier groups; and composing an extended PCI of each cell covered by the base station from the PCI of each cell covered by the base station and the group number of the subcarrier group in which at least one subcarrier corresponding to each cell is located; obtaining a mapping relationship between the base station identifiers of all base stations and the extended PCIs of all cells covered by the base stations to obtain the base station mapping table.

4. The method of claim 3, wherein, The method comprises: determining all base stations in the low-altitude network coverage range; traversing each base station to obtain PCIs of all cells in a Delaunay triangular network constructed by taking the current base station as the origin, a preset distance or a preset station level as the radius, and using a Delaunay triangulation algorithm.

5. The method of claim 1, wherein, The construction process of the target path table comprises: obtaining a time delay between each base station in the low-altitude network coverage range in a target time period. constructing a weighted graph of the low-altitude network coverage range by taking each base station as a graph node, a handover relationship between each base stations as an edge, and a time delay between each base station as a weight of the edge; adopting a Dijkstra algorithm to analyze the weighted graph, obtaining a path between each base station with a time delay less than a preset threshold, and composing a target path table.

6. The method of claim 1, wherein, switching the networked unmanned aerial vehicle to a target cell covered by the target base station according to the target path, including: determining all intermediate base stations in the target path and an access sequence number of each intermediate base station; sequentially accessing the networked unmanned aerial vehicle to each intermediate base station according to the access sequence number of each intermediate base station, until the networked unmanned aerial vehicle is switched to the target cell covered by the target base station.

7. The method of claim 2, wherein, After the networked unmanned aerial vehicle is switched to the target cell covered by the target base station according to the target path, the method further includes: releasing a wireless resource corresponding to the network slice allocated for the networked unmanned aerial vehicle. 8.A cell handover device for a networked unmanned aerial vehicle, characterized in that, including: an acquisition module, configured to acquire a measurement report of a networked unmanned aerial vehicle in a target time period; a first determination module, configured to determine a target extended PCI to which the networked unmanned aerial vehicle is to be switched to a target cell according to the measurement report, wherein the target extended PCI is composed of a PCI of the target cell and a group number of an idle subcarrier group corresponding to the target cell; a second determination module, configured to match the target extended PCI with a preset base station mapping table, determine a target base station corresponding to the target extended PCI, and determine a target path to the target base station according to a preset target path table, wherein the base station mapping table includes a mapping relationship between multiple groups of extended PCIs and multiple base stations in a low-altitude network coverage range, and the target path table includes a path between multiple base stations in the low-altitude network coverage range with a time delay less than a preset threshold in the target time period; a switching module, configured to switch the networked unmanned aerial vehicle to a target cell covered by the target base station according to the target path.

9. A communication system, characterized by The communication system includes: a networked unmanned aerial vehicle, a network device, wherein the network device includes: a source base station, a target base station, wherein, the networked unmanned aerial vehicle is configured to report a measurement report in a target time period to the source base station; The source base station is configured to acquire a measurement report of the network-connected UAV in a target time period, determine a target extended physical cell identifier (PCI) to which the network-connected UAV is to be handed over to a target cell according to the measurement report, wherein the target extended PCI is composed of a PCI of the target cell and a group number of an idle subcarrier group corresponding to the target cell, match the target extended PCI with a preset base station mapping table to determine a target base station corresponding to the target extended PCI, and determine a target path to the target base station according to a preset target path table, wherein the base station mapping table includes mapping relationships between multiple groups of extended PCIs and multiple base stations in a low-altitude network coverage range, the target path table includes paths of the multiple base stations in the low-altitude network coverage range, and a time delay of handover in the target time period of the paths is less than a preset threshold; and hand over the network-connected UAV to a target cell covered by the target base station according to the target path.

10. A network device, comprising: The network-connected UAV comprises: a memory and a processor configured to run a program stored in the memory, wherein the program is configured to perform the cell handover method of the network-connected UAV according to any one of claims 1 to 7.

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