A method and system for ultraviolet light communication cooperative networking

Abstract

This invention discloses an ultraviolet light communication cooperative networking method and system, specifically relating to the fields of free-space optical communication and cooperative networking communication technology. It includes steps such as transmitting a distance determination frame to announce the current node's location to the network and obtaining distance information between the current node and the source node; transmitting a neighbor broadcast frame to announce the IDs of neighbor nodes within one hop to the network and receiving neighbor broadcast frames from other nodes to generate a full network topology table; and dividing data transmission time slots into contention time slots and data time slots for channel contention. This invention allows multiple non-interfering transmission paths to coexist in the network, achieving spatial multiplexing and improving network throughput and flexibility.

Description

Technical Field

[0001] This invention relates to an ultraviolet light communication cooperative networking method and system, belonging to the field of free space optical communication and cooperative networking communication technology. Background Technology

[0002] Wireless optical communication uses light as the information carrier, offering advantages such as abundant spectrum resources, strong anti-interference capabilities, and high security. Ultraviolet (UV) light, as a type of wireless optical communication, uses light in the UV band as its information carrier. Due to its short wavelength, UV light is easily scattered by gas molecules and aerosol particles in the atmosphere, allowing it to bypass obstacles and achieve non-line-of-sight communication. This eliminates the need for complex tracking, aiming, and orientation systems, making it more suitable for small platforms such as drones where link alignment is difficult. Furthermore, the ozone layer strongly absorbs UV light in the 200-280nm band, resulting in minimal background light interference near the ground. Therefore, UV light has broad application scenarios in complex electromagnetic environments with strong electromagnetic interference.

[0003] However, due to the significant link loss during ultraviolet light transmission in the atmosphere, the bandwidth of ultraviolet light communication is limited, and the MAC protocol commonly used in traditional radio frequency networks cannot be directly applied to ultraviolet light networks.

[0004] In 2004, Sun et al. attempted to combine ultraviolet (UV) communication networking with traditional ad hoc systems, allowing random node access and providing forwarding capabilities. In 2011, Ke et al. attempted to combine UV communication networking with wireless mesh networks, improving network performance through enhanced routing and MAC protocols. In 2012, Zhao et al. studied path loss, bit error rate, and atmospheric attenuation when applying time-division multiplexing (TDM) technology in UV communication networking. In 2014, Li et al. proposed an improved UV communication TDM networking method, allowing geographically distant nodes to reuse the same time slots, resolving the conflict between increasing node numbers and limited time slots. In 2023, Li et al. proposed a novel UV cooperative networking (UVCN) mechanism, which, through bit simultaneous transmission and optical power superposition, can improve channel utilization while expanding network coverage. In the same year, based on UVCN, Li et al. proposed a clustering networking method, achieving better throughput and packet loss rate in multi-node networks. Li et al.'s research, through clustering, achieved spatial multiplexing between different clusters, which greatly improved the network throughput.

[0005] However, in a fixed-cluster networking approach, the selection and transfer of cluster heads undoubtedly increases the complexity of the protocol. Furthermore, all communication between nodes in a cluster is achieved through the cluster head, which limits the bandwidth of inter-cluster communication and reduces network flexibility. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an ultraviolet light communication cooperative networking method and system that allows multiple non-interfering transmission paths to exist simultaneously in the network, realizes spatial multiplexing, and improves the network throughput and flexibility.

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution: On one hand, the present invention provides a method for cooperative networking of ultraviolet light communication, comprising: An ultraviolet network includes multiple nodes. Each node transmits distance determination frames to the other nodes in sequence to announce its location to the network and obtain distance information between itself and the other nodes. Based on the distance information between the other nodes and this node, the node information within one hop of this node is obtained. Each node generates a neighbor broadcast frame based on the node information within one hop of this node. Each node sequentially transmits neighbor broadcast frames to the other nodes to announce the IDs of its neighbors within one hop to the network, and receives neighbor broadcast frames from the other nodes. Each node generates a network topology table in its own memory based on the received neighbor broadcast frames; Data transmission time slots are divided into contention time slots and data time slots; At the start of a contention time slot, all nodes are idle nodes. Idle nodes with data transmission needs generate data frames and generate the shortest path communication link according to the network topology table. Idle nodes with data transmission needs transmit the header portion of data frames to other nodes to compete for channel access. The channel competition process includes: a) In each channel contention, the node with the highest priority wins the channel contention, and its data transmission is unaffected; b. Whenever the highest priority node wins the competition, the remaining nodes calculate the communication link based on the source node ID and destination node ID in the frame header of the data frame, and mark all nodes in the communication link as working nodes and all nodes one hop away from the working node as interfering nodes. All working nodes and interfering nodes are divided into a subnet. c. Each node determines whether the subnetting affects its data transmission, resulting in two parts: nodes whose subnetting does not affect data transmission and nodes whose subnetting does affect data transmission. d. Nodes in the subnet that affect data transmission and nodes within the subnet stop competing for the channel. Nodes in the subnet that do not affect data transmission wait for the interruption field time of a data frame before entering the next contention slot to continue competing for the channel. Repeat steps a to d until no node accesses the channel to compete for the channel after waiting for more than the interruption field time of a data frame. At this point, the data slot is entered, and all subnets transmit the data portion of the data frame.

[0008] Furthermore, each node sequentially transmits distance determination frames to the remaining nodes to announce its location to the network and obtain distance information between the source node and itself, including: Preset the priority of each node; Each node transmits distance determination frames to the other nodes. After multiple lossless competitions, each node completes the transmission of distance determination frames in descending order of priority. Each node publishes its location to the network by transmitting distance determination frames, and calculates the distance information between the source node and itself based on the start time of the contention time slot and the time when it receives distance determination frames transmitted by other nodes.

[0009] Furthermore, the distance determination frame includes a synchronization field, a type field, a source node ID, and a frame end field. The synchronization field is used to enable all nodes to synchronize their clocks and communicate. The type field is used to distinguish the frame category, and it, together with the source node ID, constitutes the frame priority. The source node ID is used to indicate the number of the transmitting node and its priority. The frame end field is used to indicate the end of the frame.

[0010] Furthermore, the neighbor broadcast frame includes a synchronization field, a type field, a source node ID, a destination node ID, a neighbor node ID, and a frame end field. The destination node ID is used to indicate the number of the transmitted node and its priority, and the neighbor node ID is used to indicate the node ID that is one hop away from the source node.

[0011] Furthermore, the data frame includes a frame header and a data portion. The frame header includes a synchronization field, a type field, a source node ID, and a destination node ID. The data portion includes an interrupt field, a data field, a neighbor node ID, and a frame end field. The interrupt field consists of consecutive 0s.

[0012] Furthermore, during channel contention, a lossless contention mechanism is used to ensure that the node with the highest priority transmits the header portion of the data frame normally, thereby winning the channel contention.

[0013] Furthermore, each node determines whether the subnetting affects its data transmission, resulting in two parts: nodes where the subnetting does not affect data transmission and nodes where the subnetting does affect data transmission. Each node determines whether the communication link of the shortest path generated by its own node intersects or is directly adjacent to the communication links in the already divided subnet. If the communication link of the shortest path generated by its own node intersects or is directly adjacent to the communication links in the already divided subnet, then it is a node whose data transmission is affected by the already divided subnet. If the communication link of the shortest path generated by its own node does not intersect or is not directly adjacent to the communication links in the already divided subnet, then it is a node whose data transmission is not affected by the already divided subnet.

[0014] Furthermore, "communication links do not cross or are not directly adjacent" means that there is at least one interfering node between any two nodes in different communication links.

[0015] Furthermore, after the data transmission time slot ends, the process also includes: releasing all subnets, reverting all nodes to idle status, and starting channel contention for the next data transmission time slot.

[0016] On the other hand, the present invention provides an ultraviolet light communication cooperative networking system, comprising: Memory, used to store computer programs; A processor for executing the computer program to implement the steps of the ultraviolet light communication cooperative networking method described in any of the preceding claims.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention establishes a network topology table in each node to store link status information between all nodes, which can compress a large amount of routing calculation and other work into the node and reduce the control overhead of routing selection. When the nodes of this invention transmit data, they work in the order of first competing for the channel, determining the route, and then transmitting data. This allows for the simultaneous existence of multiple source nodes and multiple non-interfering transmission paths, achieving spatial multiplexing while improving network throughput. Due to its low control overhead, this invention allows each node to re-compete for channel space and dynamically divide the network into subnets after each data frame transmission is completed, thus improving network flexibility. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the distance determination frame in an ultraviolet light communication cooperative networking method according to one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a neighbor broadcast frame in an ultraviolet light communication cooperative networking method according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the data frame structure of an ultraviolet light communication cooperative networking method in one embodiment of the present invention; Figure 4This is a schematic diagram of data transmission time slot division in an ultraviolet light communication cooperative networking method according to one embodiment of the present invention; Figure 5 This is a schematic diagram of the data transmission time slot in an ultraviolet light communication cooperative networking method according to one embodiment of the present invention; Figure 6 This is a schematic diagram of dynamic subnetting in an ultraviolet light communication cooperative networking method according to one embodiment of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention. Example

[0020] The ultraviolet light communication cooperative networking method provided in this embodiment of the invention includes: The ultraviolet light network includes multiple nodes, each with three states: idle, interference, and working. Each node has a preset priority. In this embodiment, the priority order of the nodes is the node number, with a higher node number indicating a higher priority.

[0021] Each node transmits distance determination frames to the other nodes. After multiple lossless competitions, each node completes the transmission of distance determination frames in descending order of priority.

[0022] Distance determination frame structure as follows Figure 1 As shown, it includes a synchronization field, a type field, a source node ID, and a frame end field.

[0023] In this embodiment, the synchronization field is 12 bits long. Since this invention is based on synchronous communication and relies on strict clock synchronization, the function of the synchronization field is to complete synchronization between different nodes. It is usually a sequence of fixed content, 12'b1010_1010_1011.

[0024] The Type field is 2 bits long and is used to distinguish three different frames. The Type field and the source node ID together form the frame priority. In practical applications, fields such as business priority can also be added to the priority as needed.

[0025] The Source ID is 8 bits long. This field has two functions: first, it indicates the node's number, and different nodes in the network have different Source IDs; second, it indicates the node's priority, and nodes with larger Source IDs have higher priority. In practical applications, the length of the Source ID field can be adjusted according to the size of the network.

[0026] The End of frame field is 8 bits long and indicates the end of a frame.

[0027] Each node announces its location to the network by transmitting distance determination frames, and calculates the distance information between itself and other nodes based on the start time of the contention time slot and the time when it receives distance determination frames transmitted by other nodes.

[0028] Based on the distance information between the remaining nodes and this node, the node information within one hop of this node is obtained. Each node generates a neighbor broadcast frame based on the node information within one hop of this node.

[0029] Each node transmits neighbor broadcast frames to other nodes to announce the IDs of its neighbors within one hop to the network, and receives neighbor broadcast frames from other nodes.

[0030] Neighbor broadcast frame structure as follows Figure 2 As shown, it includes a synchronization field, a type field, a source node ID, a destination node ID, neighbor node IDs, and a frame end field. The synchronization field, type field, source node ID, and frame end field are the same as those in the distance determination frame, so they will not be elaborated upon here. The destination node ID is 8 bits long and is used to indicate the number of the transmitted node and its priority. In practice, this field functions the same as the source node ID. The neighbor node ID is 100 bits long and is used to indicate the node ID that is one hop away from the source node. In practical applications, the length of this field can be modified according to the size of the network.

[0031] Each node generates a network topology table in its own memory based on the received neighbor broadcast frames.

[0032] Data transmission time slots are divided into contention time slots and data time slots, such as Figure 4 As shown, T1-T n-1 To compete for time slots, T n In the data time slot, nodes compete for the channel by transmitting the header portion of the data frame and the data portion of the data frame.

[0033] The structure of a data frame is as follows Figure 3As shown, it includes a synchronization field, a type field, a source node ID, and a destination node ID. The data portion includes an interrupt field, a data field, a neighbor node ID, and a frame end field. The fields identical to those in the distance determination frame and the neighbor broadcast frame are identical and will not be elaborated upon here. The interrupt field (Interrupt) is used by nodes to determine whether channel contention has ended; it consists of 4 consecutive "0" bits. The data field (Data) is 462 bits long and stores the core content of the data frame. This embodiment of the invention uses a fixed pin length system with a frame length of 500 bits. In practical applications, the frame length can be adjusted according to actual needs.

[0034] The priority of the three types of frames, from highest to lowest, is: distance determination frame > neighbor broadcast frame > data frame.

[0035] like Figure 5 As shown, the data transmission time slot is as follows: at the start of the contention time slot T1, all nodes are idle nodes. Idle nodes with data transmission needs generate data frames and generate the shortest path communication link according to the network topology table. Then, they transmit the frame header of the data frame to the other nodes to compete for the channel.

[0036] The channel contention process includes: a. In each channel contention, a lossless contention mechanism is used to ensure that the node with the highest priority transmits the header of the data frame normally in order to win the channel contention.

[0037] b. Whenever the highest priority node wins the competition, the remaining nodes calculate the communication link based on the source node ID and destination node ID in the frame header of the data frame, and mark all nodes in the communication link as working nodes and all nodes one hop away from the working node as interfering nodes. All working nodes and interfering nodes are divided into a subnet.

[0038] c. Each node determines whether the subnetting affects its data transmission, resulting in two categories: nodes where subnetting does not affect data transmission and nodes where subnetting does affect data transmission. Specifically: Each node determines whether the communication link of the shortest path generated by its own node intersects or is directly adjacent to the communication links in the already divided subnet (not intersecting or directly adjacent means that any two nodes from different communication links are separated by only one interfering node). If the communication link of the shortest path generated by its own node intersects or is directly adjacent to the communication links in the already divided subnet, then it is a node whose data transmission is affected by the already divided subnet. If the communication link of the shortest path generated by its own node does not intersect or is directly adjacent to the communication links in the already divided subnet, then it is a node whose data transmission is not affected by the already divided subnet.

[0039] d. Nodes in the subnet that affect data transmission and nodes within the subnet cease channel contention. Nodes in the subnet that do not affect data transmission wait for the interrupt field time of one data frame (a 4-bit interrupt field corresponds to 4 clock cycles) before entering the next contention slot T2 to continue channel contention. Steps a~d are repeated until the Tth frame is reached. n-1 If no node transmits data after waiting for more than the interrupt field time of one data frame in a contention time slot, in this embodiment, if no node transmits data in the 5th clock cycle, it means that no node needs to access the channel for channel contention, and the data time slot T is entered. n The data portion of all subnet transmission data frames, and the final dynamic subnetting structure are as follows: Figure 6 As shown.

[0040] After the data portion of the data frame has been transmitted, all subnets are released, all nodes return to the idle node state, and competition for the next data transmission time slot begins, and this cycle repeats.

[0041] Thus, through the aforementioned ultraviolet light communication cooperative networking method, the network achieves spatial multiplexing through dynamic subnetting, effectively improving network throughput and network flexibility. Example

[0042] Based on Example 1, this example provides an ultraviolet light communication cooperative networking system, including: Memory is used to store computer programs.

[0043] A processor is used to execute the computer program to implement the steps of the ultraviolet light communication cooperative networking method described in Embodiment 1.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for cooperative networking of ultraviolet light communication, characterized in that, include: An ultraviolet network includes multiple nodes. Each node transmits a distance determination frame to the other nodes to announce its location to the network and obtain distance information between itself and the other nodes. Based on the distance information between the other nodes and this node, the node information within one hop of this node is obtained. Each node generates a neighbor broadcast frame based on the node information within one hop of this node. Each node transmits neighbor broadcast frames to other nodes to announce the IDs of its neighbors within one hop to the network, and receives neighbor broadcast frames from other nodes. Each node generates a network topology table in its own memory based on the received neighbor broadcast frames; Data transmission time slots are divided into contention time slots and data time slots; At the start of a contention time slot, all nodes are idle nodes. Idle nodes with data transmission needs generate data frames and generate the shortest path communication link according to the network topology table. Idle nodes with data transmission needs transmit the header portion of data frames to other nodes to compete for channel access. The channel competition process includes: a) In each channel contention, the node with the highest priority wins the channel contention, and its data transmission is unaffected; b. Whenever the highest priority node wins the competition, the remaining nodes calculate the communication link based on the source node ID and destination node ID in the frame header of the data frame, and mark all nodes in the communication link as working nodes and all nodes one hop away from the working node as interfering nodes. All working nodes and interfering nodes are divided into a subnet. c. Each node determines whether the subnetting affects its data transmission, resulting in two parts: nodes where the subnetting does not affect data transmission and nodes where the subnetting does affect data transmission. Each node determines whether the communication link of the shortest path generated by its own node intersects or is directly adjacent to the communication links in the already divided subnet. If the communication link of the shortest path generated by its own node intersects or is directly adjacent to the communication links in the already divided subnet, then it is a node whose data transmission is affected by the already divided subnet. If the communication link of the shortest path generated by its own node does not intersect or is not directly adjacent to the communication links in the already divided subnet, then it is a node whose data transmission is not affected by the already divided subnet. Communication links not intersecting or not directly adjacent means that there is at least one interfering node between any two nodes in different communication links. d. Nodes in the subnet that affect data transmission and nodes within the subnet stop competing for the channel. Nodes in the subnet that do not affect data transmission wait for the interruption field time of a data frame before entering the next contention slot to continue competing for the channel. Repeat steps a to d until no node accesses the channel to compete for the channel after waiting for more than the interruption field time of a data frame. At this point, the data slot is entered, and all subnets transmit the data portion of the data frame.

2. The ultraviolet light communication cooperative networking method according to claim 1, characterized in that, Each node transmits a distance determination frame to the other nodes to announce its location to the network and obtain distance information between itself and the other nodes, including: Preset the priority of each node; Each node transmits distance determination frames to the other nodes. After multiple lossless competitions, each node completes the transmission of distance determination frames in descending order of priority. Each node announces its location to the network by transmitting distance determination frames, and calculates the distance information between itself and other nodes based on the start time of the contention time slot and the time when it receives distance determination frames transmitted by other nodes.

3. The ultraviolet light communication cooperative networking method according to claim 1, characterized in that, The distance determination frame includes a synchronization field, a type field, a source node ID, and a frame end field. The synchronization field is used to enable all nodes to synchronize their clocks and communicate. The type field is used to distinguish the frame category, and it, together with the source node ID, constitutes the frame priority. The source node ID is used to indicate the number of the transmitting node and its priority. The frame end field is used to indicate the end of the frame.

4. The ultraviolet light communication cooperative networking method according to claim 1, characterized in that, The neighbor broadcast frame includes a synchronization field, a type field, a source node ID, a destination node ID, a neighbor node ID, and a frame end field. The destination node ID is used to indicate the number of the transmitted node and its priority. The neighbor node ID is used to indicate the node ID that is within one hop of the source node.

5. The ultraviolet light communication cooperative networking method according to claim 1, characterized in that, The data frame includes a frame header and a data portion. The frame header includes a synchronization field, a type field, a source node ID, and a destination node ID. The data portion includes an interrupt field, a data field, a neighbor node ID, and a frame end field. The interrupt field consists of consecutive 0s.

6. The ultraviolet light communication cooperative networking method according to claim 1, characterized in that, During channel contention, a lossless contention mechanism is used to ensure that the node with the highest priority transmits the header portion of the data frame normally, thereby winning the channel contention.

7. The ultraviolet light communication cooperative networking method according to claim 1, characterized in that, After the data transmission time slot ends, the process also includes: releasing all subnets, restoring all nodes to idle status, and starting channel contention for the next data transmission time slot.

8. An ultraviolet light communication cooperative networking system, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the steps of the ultraviolet light communication cooperative networking method according to any one of claims 1 to 7.

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