# Research on Networking Protocols for Large-Scale Mobile Ultraviolet Communication Networks
## 2 LSM-UVCN
### Node State Transition  
To ensure the establishment of multiple transmission paths and the mutual isolation between these paths, the protocol classifies nodes into three states: Idle, Silent, and Work. Nodes in the Idle state represent unoccupied nodes, and all nodes are initially in the Idle state. The Work state indicates that the node is occupied by a transmission path. Nodes in the Silent state are primarily tasked with isolating different transmission paths during the data transmission time slot to prevent mutual interference. During the channel competition phase, nodes applying for channel competition need to meet three requirements:  
1. The node is in the Idle state. 2. The node has data to transmit. 3. There is an available transmission path between the node and the destination node. Whenever a node wins the channel competition, by traversing the connection matrix and employing a routing algorithm that gives priority to high-priority nodes, the transmission path between the source node and the destination node is determined accordingly. At this time, the state of all nodes on the transmission path changes from the Idle state to the  
Figure 4: Hop-by-hop neighbor table and path establishment example. Work state, and other Idle nodes within one hop of the nodes in the Work state change to the Silent state. After each channel competition, nodes promptly modify the states of various nodes in the connection matrix. Nodes that have changed to the Work state cannot be occupied by subsequently generated transmission paths. Nodes that have changed to the Silent state also cannot be selected as Work nodes by subsequently generated transmission paths, but the same Silent nodes can be multiplexed by multiple different paths. After the state transition is completed, nodes that still meet the competition conditions will continue to compete for the channel in the next competition time slot. Through multiple consecutive competitions, the nodes in the network are successfully divided into multiple transmission paths. When no nodes continue to compete for the channel, the network enters the data transmission stage. At this time, all nodes that have won the competition start to transmit data simultaneously. The duration of the data transmission stage is a constant \(T_{\text{data}}\), and each source node dynamically adjusts the payload to be transmitted \(B_{\text{data}}\) according to the number of hops \(m\) required to reach the destination node, with \(B_{\text{data}}=T/m\) bits. During the data transmission stage, only nodes in the Work state will transmit or forward data, while nodes in the Idle and Silent states remain silent throughout and do not forward any data. Through the \"isolation zone\" set by the Silent nodes, each transmission path can avoid mutual interference, achieving SDM. After the data transmission is completed, all nodes return to the Idle state and enter the next complete transmission cycle. Figure 5 depicts a \(5\times 5\) network. Through three rounds of channel competition, three transmission paths are successively generated. Different paths do not reuse nodes in the work state, and they are separated from each other by nodes in the silent state, effectively preventing interference between links. At the start of data transmission, three source nodes initiate data transmission simultaneously. In Transmission Path 1, the distance between the source node and the destination node is two hops, so the actual amount of data that can be transmitted is (\(T_{\text{data}}/2\)) bits. Similarly, the amounts of data that can be transmitted in Transmission Paths 2 and 3 are (\(T_{\text{data}}/3\)) bits and \(T_{\text{data}}\) bits, respectively. After the data transmission is completed, all nodes return to the Idle state, and a new round of competition commences. The protocol relies on the established connection matrix. Through multiple rounds of competition and the isolation provided by silent nodes, it can fully utilize the increased  
Figure 5: Example of path generation and state transition.