Non-timing random access networking method and device applied to rail transit, and medium

Abstract

The invention relates to the technical field of rail transit wireless communication, and provides a non-timing random access networking method and device applied to rail transit and a medium, and the method comprises the steps: initializing a network, generating a local topology table, and dividing a time slot structure; the time slot structure comprises a competition time slot, a ranging time slot and a data time slot; the node completes random access based on the competition time slot; the node completes distance measurement based on the distance measurement time slot and completes data transmission by using the data time slot; dynamically adjusting the time slot length based on the ranging distance; and performing network maintenance and fault recovery, and updating the local topology table and the time slot structure. Through the non-timing system design, global clock synchronization is not needed, the complexity and energy consumption of the system are reduced, and efficient and reliable short-distance ranging and data transmission can be realized in a rail transit scene.

Description

Technical Field

[0001] The present invention relates to the field of rail transit wireless communication technology, and in particular to a non-time-synchronized random access networking method, device and medium applied to rail transit. Background Art

[0002] Rail transit primarily includes high-speed rail and subways, both of which are already in widespread use in China, and the latter are gradually expanding globally. Rail transit scenarios require short-range, high-precision ranging and low-latency data transmission between trains, trackside equipment, mobile terminals, and other nodes, enabling applications such as coordinated train formation control, obstacle detection, and dynamic scheduling.

[0003] In the highly dynamic, multi-node complex environment of rail transit, traditional time synchronization networks rely on global clock synchronization, which has problems such as high synchronization overhead and weak anti-interference ability. Summary of the Invention

[0004] The present invention aims to provide a non-time-synchronized random access networking method, device and medium for rail transit, so as to solve the problems that traditional time-synchronized networks rely on global clock synchronization, have large synchronization overhead and weak anti-interference ability.

[0005] In a first aspect, the present invention provides a non-time-synchronized random access networking method for rail transit, comprising:

[0006] Initialize the network, generate a local topology table and divide the time slot structure; the time slot structure includes contention time slots, ranging time slots and data time slots;

[0007] The node completes random access based on the contention time slot;

[0008] The node completes ranging based on the ranging time slot and completes data transmission using the data time slot;

[0009] Dynamically adjust the time slot length based on the ranging distance;

[0010] Perform network maintenance and fault recovery, and update the local topology table and time slot structure.

[0011] In some embodiments, after the network is initialized, the node performs the following operations:

[0012] The node scans channels within a predefined frequency band and listens to the broadcast frames of neighboring nodes. By receiving the broadcast frames, the node builds a local topology table and records the information of neighboring nodes.

[0013] According to the local topology table and channel quality, the node dynamically divides the time slot structure.

[0014] In some embodiments, the node performs random access based on the contention time slot, including:

[0015] The node sends an access request frame with probability p in the contention time slot;

[0016] If a node does not receive an acknowledgment frame after sending an access request frame, it is considered a transmission conflict, the number of conflicts Nct is increased by 1, and the access probability is updated; at the same time, the node enters the backoff state and waits for a random delay before retrying access;

[0017] If the access request is successful, the neighboring node replies with a confirmation frame and allocates exclusive ranging and data time slots for the node. At the same time, the time slot allocation information is notified to the entire network through a broadcast frame to ensure that each node synchronously updates the time slot structure.

[0018] In some embodiments, the formula for updating the access probability is expressed as:

[0019]

[0020] Among them, p max is the maximum access probability in the historical contention time slot, λ is the collision attenuation coefficient, p0 is the initial access probability, and Nct is the number of collisions.

[0021] In some embodiments, the node completes ranging based on the ranging time slot, including:

[0022] The node sends the ranging signal in the allocated ranging time slot and records the sending timestamp t Tx ;

[0023] Neighboring nodes receive ranging signals and record the receiving timestamp t Rx , and reply with the receiving timestamp t Rx Ranging response frame;

[0024] The sending node sends the timestamp t Tx and receiving timestamp t Rx Calculate the distance d, the calculation formula is expressed as:

[0025]

[0026] Where Δt pro is the fixed processing delay and c is the speed of light.

[0027] In some embodiments, using the data time slot to complete data transmission includes:

[0028] After the ranging is completed, the node uses the adjacent data time slot to transmit service data;

[0029] Among them, data transmission uses coding technology to dynamically adjust the transmission rate according to the channel quality.

[0030] In some embodiments, dynamically adjusting the time slot length based on the ranging distance includes:

[0031]

[0032] Among them, T slot is the time slot length, d max is the maximum ranging distance; T bf For protection interval.

[0033] In some embodiments, performing network maintenance and fault recovery and updating the local topology table and time slot structure include:

[0034] Nodes periodically broadcast topology update frames to notify neighbors of their own state changes. Neighboring nodes adjust their local topology tables based on the topology update frames.

[0035] If a node does not receive a broadcast frame from a neighbor node within multiple consecutive cycles, it is considered to be failed and deleted from the local topology table; the time slot resources of the failed node are reallocated to other nodes;

[0036] When a major change occurs in the network topology, the network reconstruction process is triggered; all nodes re-initialize the network and build a new time slot structure and local topology table.

[0037] In a second aspect, the present invention provides an electronic device, comprising:

[0038] at least one processor; and a memory communicatively coupled to the at least one processor;

[0039] The memory stores instructions that can be executed by the at least one processor, and the at least one processor executes the above method by executing the instructions stored in the memory.

[0040] In a third aspect, the present invention provides a computer-readable storage medium for storing instructions, which implement the above method when the instructions are executed.

[0041] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0042] 1. The present invention adopts a non-time-synchronized design, which does not require global clock synchronization, reduces system complexity and energy consumption, and can achieve efficient and reliable short-distance ranging and data transmission in rail transit scenarios, and has broad application prospects.

[0043] 2. The present invention supports high-density node scenarios through probabilistic backoff and dynamic time slot allocation.

[0044] 3. The present invention completes ranging and data transmission in the same time slot, thereby improving spectrum utilization.

[0045] 4. The present invention optimizes the protection interval and time slot allocation for multipath effects and high-speed mobility, and can better adapt to rail transit scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a flow chart of a non-time-synchronized random access networking method for rail transit proposed in an embodiment of the present invention.

[0047] Figure 2 Schematic diagram of the time slot structure in an embodiment of the present invention.

[0048] Figure 3 This is a flow chart of the coordination of ranging and data transmission in an embodiment of the present invention.

[0049] Figure 4 This is a schematic structural diagram of an electronic device proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0051] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0052] The traditional time-synchronized network relies on global clock synchronization, which has the problems of large synchronization overhead and weak anti-interference ability. The present invention proposes a non-time-synchronized random access networking method for rail transportation, which is suitable for the timing allocation and function division of multi-node random access self-organizing networks in a non-time-synchronized (no global time synchronization required) environment. Figure 1 As shown, the embodiment of the present invention proposes a non-time-synchronized random access networking method for rail transit, including the following steps:

[0053] S100: Network initialization.

[0054] In rail transit scenarios, all nodes are not as densely packed as in traditional scenarios. Nodes are primarily arranged along one side of the track, or at stations with a limited number of tracks and corresponding train nodes. Network initialization is the first step in establishing an ad hoc network. All nodes (including onboard equipment, trackside equipment, and mobile terminals used for networking such as distance measurement, data transmission, and voice) enter the initialization state after startup and perform the following operations:

[0055] S1001: Channel Scanning and Neighbor Discovery: A node performs channel scanning within a predefined frequency band and listens for broadcast frames from neighboring nodes. By receiving these frames, the node constructs a local topology table and records neighbor node information. These broadcast frames contain the node ID, location information, and timing requirements (such as ranging or data transmission priority).

[0056] S1002: Time slot structure division: Based on the local topology table and channel quality, the node dynamically divides the time slot structure. In some embodiments, Figure 2 As shown, time slots include the following three categories:

[0057] (1) Contention slot: used for random access request of nodes.

[0058] (2) Ranging time slot: used to send and receive ranging signals.

[0059] (3) Data slot: used to transmit business data (such as location, speed, and status information).

[0060] S200: Random access phase.

[0061] Random access is the core mechanism of networking, ensuring that multiple nodes can efficiently compete for channel resources without central scheduling. It specifically includes the following steps:

[0062] S2001: Send Access Request. A node sends an access request frame with probability p during a contention time slot. The access request frame includes the node ID, timing requirements (such as ranging priority), and the current backoff state. Generally, the initial access probability p0 is preset based on the network density. In high-density scenarios, the initial access probability p0 is lower to reduce conflicts.

[0063] S2002: Conflict detection and avoidance.

[0064] If a node does not receive an acknowledgment frame after sending an access request frame, it is considered a transmission conflict. The number of conflicts Nct is incremented by 1, and the access probability is updated. The formula for updating the access probability is expressed as:

[0065] p=min(p max ,p0·e -λ·Nct )

[0066] Among them, pmax is the maximum access probability in the historical contention time slot; λ is the conflict attenuation coefficient, which is generally set to 0.1≤λ≤0.5.

[0067] After detecting a transmission conflict, the node enters a backoff state and waits for a random delay before retrying access. In some embodiments, the random delay is generated by using a linear feedback shift register (LFSR) to generate a pseudo-random number.

[0068] S2003: Access Confirmation and Resource Allocation. If the access request is successful, the neighboring node responds with an acknowledgment frame and allocates a dedicated ranging and data slot for the node. This slot allocation information is broadcast to the entire network via a broadcast frame, ensuring that all nodes synchronize their slot structures.

[0069] S300: Coordination of ranging and data transmission.

[0070] Ranging and data transmission are the core functions of rail transit scenarios. The present invention achieves efficient collaboration between the two through time slot division. Figure 3 As shown, the specific steps include:

[0071] S3001: Ranging timeslot operation.

[0072] S30011: The node sends a ranging signal (such as a UWB pulse signal) in the allocated ranging time slot and records the sending timestamp t Tx .

[0073] S30012: The neighboring node receives the ranging signal and records the receiving timestamp t Rx , and reply with the receiving timestamp t Rx Ranging response frame.

[0074] S30013: The sending node sends the timestamp t Tx and receiving timestamp t Rx Calculate the distance d, the calculation formula is expressed as:

[0075]

[0076] Where Δt pro is the fixed processing delay, which is eliminated through pre-calibration; c is the speed of light.

[0077] S3002: Data timeslot operation.

[0078] S30021: After completing ranging, the node uses adjacent data slots to transmit service data. The service data frame includes the node ID, location information, speed information, and more. In some embodiments, data transmission can utilize encoding techniques such as PSK, dynamically adjusting the transmission rate based on channel quality to ensure high reliability and low latency.

[0079] S400: Dynamic timeslot adjustment.

[0080] Rail transit scenarios are highly dynamic and dense, and dynamic time slot adjustment is key to ensuring network performance. The time slot length T occupied by the ranging signal slot Determined by propagation delay and resolution:

[0081]

[0082] Among them, d max is the maximum ranging distance; T bf is the protection interval. The time slot length is dynamically optimized according to the ranging distance. When the train approaches at high speed, the ranging time slot length T is shortened. slot To adapt to rapidly changing distance information.

[0083] S500: Network maintenance and fault recovery.

[0084] S5001: Topology Update. A node periodically broadcasts a topology update frame to notify its neighbors of state changes (such as location update or node failure). Neighboring nodes adjust their local topology tables based on the topology update frame.

[0085] S5002: Fault Detection and Recovery. If a node does not receive a broadcast frame from a neighboring node for multiple consecutive cycles, the node is considered failed and deleted from the local topology table. The failed node's time slot resources are reallocated to other nodes.

[0086] S5003: Network Reconfiguration. When a major change occurs in the network topology (e.g., train formation reorganization), the network reconstruction process is triggered. All nodes re-initialize the network and construct a new time slot structure and local topology table.

[0087] Based on the same technical concept, an embodiment of the present invention further provides an electronic device that can implement the non-synchronous random access networking method process for rail transit provided in the above embodiment of the present invention. In one embodiment, the electronic device can be a server, or a terminal device or other electronic device. Figure 4 As shown, the electronic device may include:

[0088] At least one processor, and a memory connected to the at least one processor. The embodiment of the present invention does not limit the specific connection medium between the processor and the memory. Figure 4The example in this article is that the processor and memory are connected via a bus. Figure 4 The connections between the other components are shown in bold lines, which are only for illustration and not limiting. The bus can be divided into address bus, data bus, control bus, etc. Figure 4 The processor is represented by a single thick line, but this does not mean that there is only one bus or only one type of bus. Alternatively, the processor can also be called a controller, without any limitation on the name.

[0089] In an embodiment of the present invention, the memory stores instructions that can be executed by at least one processor. By executing the instructions stored in the memory, the at least one processor can execute a non-time-synchronous random access networking method for rail transit discussed above.

[0090] Among them, the processor is the control center of the device, which can use various interfaces and lines to connect the various parts of the entire control device, and monitor the device as a whole by running or executing instructions stored in the memory and calling data stored in the memory, the various functions of the device and processing data.

[0091] In an optional design, the processor may include one or more processing units, and the processor may integrate an application processor and a modem processor, wherein the application processor primarily processes the operating system, user interface, and application programs, and the modem processor primarily processes wireless communications. It is understood that the modem processor may not be integrated into the processor. In some embodiments, the processor and memory may be implemented on the same chip, or in some embodiments, they may be implemented on separate chips.

[0092] The processor can be a general-purpose processor, such as a CPU, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the non-synchronous random access networking method for rail transit disclosed in the embodiments of the present invention can be directly implemented as execution by a hardware processor, or can be executed by a combination of hardware and software modules in the processor.

[0093] As a non-volatile computer-readable storage medium, memory can be used to store non-volatile software programs, non-volatile computer executable programs and modules. Memory can include at least one type of storage medium, for example, can include flash memory, hard disk, multimedia card, card-type memory, random access memory (Random Access Memory, RAM), static random access memory (Static Random Access Memory, SRAM), programmable read-only memory (Programmable Read Only Memory, PROM), read-only memory (Read Only Memory, ROM), electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, EEPROM), magnetic memory, disk, optical disk, etc. Memory is any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory in the embodiment of the present invention can also be a circuit or any other device that can realize a storage function, for storing program instructions and / or data.

[0094] By designing and programming a processor, the code corresponding to the non-synchronous random access networking method for rail transit described in the aforementioned embodiment can be embedded in the chip, enabling the chip to execute the steps of the method in the aforementioned embodiment during operation. Designing and programming a processor is well known to those skilled in the art and will not be further described here.

[0095] Based on the same inventive concept, an embodiment of the present invention further provides a storage medium storing computer instructions. When the computer instructions are executed on a computer, the computer executes a non-time-synchronized random access networking method for rail transit discussed above.

[0096] In some optional embodiments, the present invention also provides various aspects of a non-synchronous random access networking method for rail transit, which can also be implemented in the form of a program product, which includes program code. When the program product is run on the device, the program code is used to enable the control device to execute the steps of a non-synchronous random access networking method for rail transit according to various exemplary embodiments of the present invention described above in this specification.

[0097] It should be noted that although several units or subunits of the device are mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to an embodiment of the present invention, the features and functions of two or more units described above can be embodied in one unit. Conversely, the features and functions of a unit described above can be further divided into multiple units to be embodied. In addition, although the operations of the method of the present invention are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in this specific order, or that all the operations shown must be performed to achieve the desired results. Additionally or alternatively, certain steps can be omitted, multiple steps can be combined into one step, and / or one step can be decomposed into multiple steps.

[0098] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0099] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as a combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a server, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the process in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0100] Program code for performing the operations of the present invention may be written using any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computing device, partially on the user's device, as a stand-alone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0101] Where a remote computing device is involved, the remote computing device may be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., through the Internet using an Internet service provider).

[0102] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0103] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0104] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A non-time-synchronized random access networking method for rail transit, characterized in that: include: Initialize the network, generate a local topology table and divide the time slot structure; the time slot structure includes contention time slots, ranging time slots and data time slots; The node completes random access based on the contention time slot; The node completes ranging based on the ranging time slot and completes data transmission using the data time slot; Dynamically adjust the time slot length based on the ranging distance; Perform network maintenance and fault recovery, and update the local topology table and time slot structure.

2. The non-time-synchronized random access networking method for rail transit according to claim 1, characterized in that: After the network is initialized, the node performs the following operations: The node scans channels within a predefined frequency band and listens to the broadcast frames of neighboring nodes. By receiving the broadcast frames, the node builds a local topology table and records the information of neighboring nodes. According to the local topology table and channel quality, the node dynamically divides the time slot structure.

3. The non-time-synchronized random access networking method for rail transit according to claim 1, characterized in that: The node completes random access based on the contention time slot, including: The node sends an access request frame with probability p in the contention time slot; If a node does not receive an acknowledgment frame after sending an access request frame, it is considered a transmission conflict, the number of conflicts Nct is increased by 1, and the access probability is updated; at the same time, the node enters the backoff state and waits for a random delay before retrying access; If the access request is successful, the neighboring node replies with a confirmation frame and allocates exclusive ranging and data time slots for the node. At the same time, the time slot allocation information is notified to the entire network through a broadcast frame to ensure that each node synchronously updates the time slot structure.

4. The non-time-synchronized random access networking method for rail transit according to claim 3, characterized in that: The formula for updating the access probability is expressed as: p=min(p max ,p0·e -λ·Nct ) Among them, p max is the maximum access probability in the historical contention time slot, λ is the collision attenuation coefficient, p0 is the initial access probability, and Nct is the number of collisions.

5. The non-time-synchronous random access networking method for rail transit according to claim 1, characterized in that: The node completes ranging based on the ranging time slot, including: The node sends the ranging signal in the allocated ranging time slot and records the sending timestamp t Tx ; Neighboring nodes receive ranging signals and record the receiving timestamp t Rx , and reply with the receiving timestamp t Rx Ranging response frame; The sending node sends the timestamp t Tx and receiving timestamp t Rx Calculate the distance d, the calculation formula is expressed as: Where Δt pro is the fixed processing delay and c is the speed of light.

6. The non-time-synchronized random access networking method for rail transit according to claim 1, characterized in that: The method of using the data time slot to complete data transmission includes: After the ranging is completed, the node uses the adjacent data time slot to transmit service data; Among them, data transmission uses coding technology to dynamically adjust the transmission rate according to the channel quality.

7. The non-time-synchronized random access networking method for rail transit according to claim 1, characterized in that: The dynamically adjusting the time slot length based on the ranging distance includes: Among them, T slot is the time slot length, d max is the maximum ranging distance; T bf For protection interval.

8. The non-time-synchronized random access networking method for rail transit according to claim 1, characterized in that: The performing of network maintenance and fault recovery and updating of the local topology table and time slot structure include: Nodes periodically broadcast topology update frames to notify neighbors of their own state changes. Neighboring nodes adjust their local topology tables based on the topology update frames. If a node does not receive a broadcast frame from a neighbor node within multiple consecutive cycles, it is considered to be failed and deleted from the local topology table; the time slot resources of the failed node are reallocated to other nodes; When a major change occurs in the network topology, the network reconstruction process is triggered; all nodes re-initialize the network and build a new time slot structure and local topology table.

9. An electronic device, characterized in that: include: at least one processor; and a memory communicatively coupled to the at least one processor; The memory stores instructions that can be executed by the at least one processor, and the at least one processor executes the method according to any one of claims 1 to 8 by executing the instructions stored in the memory.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium is used to store instructions, and when the instructions are executed, the method according to any one of claims 1 to 8 is implemented.

Images