Routing optimization method for PLC navigation-aid light control based on relay cache

Abstract

The invention relates to a relay cache-based routing optimization method for PLC (Programmable Logic Controller) navigational light control. Navigation-aiding light plays a key role in aircraft take-off and landing safety, and when a PLC technology is used for achieving navigation-aiding light control, long-distance power line transmission has the problems of unreliability and time delay. According to the method, the relay device is deployed in the navigation-aid light transmission model, and the computing power and instruction cache of the relay node are utilized, so that effective routing optimization is realized. The specific process comprises the steps that the CCO broadcasts a control command, the nodes form a local relay routing table, the CCO selects a global relay routing path and sends an instruction to the PCO, the PCO caches the instruction and forwards the instruction to other nodes, and finally the multi-layer relay routing network is established. The method has the advantages that dynamic routing updating and standby path caching are realized, and the communication efficiency and reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of communications, specifically to a routing optimization method for PLC-based navigation lighting control based on relay buffering. Background Technology

[0002] Navigational lights are visual aids that ensure safe takeoff, landing, and taxiing for aircraft in low-visibility or complex environments. Their operational status affects aircraft takeoff and landing safety and is one of the key infrastructures for safe airport operations. Using PLC technology, various navigational aids can be connected into a network without the need for additional communication infrastructure, enabling interconnectivity between facilities and thus reducing costs while improving communication and control efficiency. Furthermore, the control center can connect to the navigational lights via PLCs to send commands and control parameters such as the on / off state and brightness, achieving remote control and monitoring. In addition, the control center can use PLC technology to diagnose faults in the navigational aids, allowing for timely dispatch of maintenance personnel to address issues and ensuring their normal operation.

[0003] PLC (Power Line Control) is a special communication method that uses existing power lines to transmit analog or digital signals via carrier waves. Its biggest advantage is that it eliminates the need for rewiring; data transmission can be achieved simply by utilizing existing power lines. Currently, commercial navigation lighting monitoring systems based on PLC primarily employ a scheme where signals are transmitted through power isolation transformers and coupled to the secondary winding at branch nodes to achieve signal modulation and demodulation. Because the main communication circuit requires signals to traverse multiple power isolation transformers, long-term application at several airports has revealed unsatisfactory performance. Furthermore, relevant research data indicates that power isolation transformers used in power distribution systems in power line communication have a strong blocking and attenuation effect on PLC signals above 500kHz, severely impacting communication quality and bandwidth. Therefore, the unique power supply system of navigation lighting presents challenges for the application of PLC technology in this field. Summary of the Invention

[0004] In order to solve the technical problems existing in the background art, this invention proposes a routing optimization method for PLC navigation lighting control based on relay buffer, which helps to solve the problems of unreliability and time delay in long-distance power line transmission.

[0005] The technical solution of this invention is: to abstract the navigation light transmission model as follows: Figure 2 The model shown has a CCO (Content Control Operator) as the transmitting end, and there are [various components] on the entire circuit. One load, representing Each node in this model deploys a relay device. Each relay device is configured with a certain computing power and supports instruction caching. Instructions generally only include time and on / off status, so a small-capacity cache is feasible. Furthermore, the CCO selects appropriate nodes to activate the relay function based on real-time network channel conditions. To obtain effective relay routes and formulate suitable relay routing tables, the CCO needs to obtain the channel conditions between nodes and use its computing power to calculate suitable relay routes. The implementation process of the relay-cached routing scheme is as follows: Step 1: The CCO broadcasts control commands from all nodes, and all nodes listen for them. Each node that receives a command buffers the command. Each node then constructs a Layer 1 local relay routing table based on the channel conditions of other nodes it has monitored, and sends an ACK command along with the Layer 1 local relay routing table back to the CCO. Step two: The CCO reads the relay routing tables returned by nodes that can communicate directly. By comparing the channel state information of each node with other nodes, it selects suitable nodes as relay nodes (these relay nodes are called the first-layer PCOs) to obtain the initial global relay routing table. Then, the CCO sends the optimal route to the first-layer PCOs in order to select the best channel conditions to send control commands to the nodes that the first-layer PCOs can communicate with. Step 3: After receiving the CCO instruction, the Layer 1 PCO caches the route selected by the CCO and uses this route to send the cached control instructions to other nodes (these control instructions do not need to include the control instructions from the sending node). After receiving the control instructions, other nodes form a Layer 2 relay routing table based on the channel conditions of the remaining nodes they have monitored, and send back an ACK instruction and a Layer 2 local relay routing table to the CCO. Step four: After reading the Layer 2 local relay routing table, the CCO compares the channel state information of each node with other nodes, selects suitable nodes as relay nodes (these relay nodes are called Layer 2 PCOs), and updates the global relay routing table. Then, the CCO sends the optimal route to the Layer 2 PCO through the Layer 1 path; Step 5: The second-layer PCO repeats step 3 and sends back the third-layer local routing table; Step six: The CCO repeats step four, selects the third-layer PCO, and sends the optimal route path to the third-layer PCO based on the previously selected optimal route path. Step 7: Repeat steps 3 and 4 until a four-layer PCO is established. If any node still has not received a control command or sent an ACK instruction, then that node is considered to be faulty. Step 8: The CCO and PCO cache the optimal routing path for the next control command to be sent.

[0006] The advantages of this application are as follows: After a certain period of time, the CCO sends an update command to each node through the current optimal route, clears the control commands cached in the PCO and the local relay routing table of each node, so that the PCO can cache new control commands and each node can generate new relay routing tables. In addition, the optimal route cached in the PCO is saved as a backup route when the newly generated local relay routing table fails to connect to a node. Attached Figure Description

[0007] Figure 1 Design the routing for the CCO routing computation node side.

[0008] Figure 2 This is a model diagram.

[0009] Figure 3 This is a comparison chart of the simulation results of the routing algorithm.

[0010] Figure 4 The test results show the connectivity rates of different nodes. Detailed Implementation

[0011] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. Example 1

[0012] To determine the effectiveness of the proposed routing algorithm in reducing latency and the impact of network environment on node data reception latency, simulations were performed on a PC with an i9-9900K processor and 32GB of memory using Matlab 2019b. The simulation marginal parameters were set as follows: Marginal parameters Setting value Network configuration 100 nodes (1 CCO, 99 navigation lights) CCO connectivity 30% (To prevent excessive power from causing interference, the CCO is set to communicate directly with 30% of the nodes.) Inter-node connectivity 10% (Refer to test results in 5.2: 6% to 25%. To prevent interference, the node is configured to monitor 10% of other nodes). Two-way communication time between nodes 150ms (average value set based on test results) ACK waiting time 500ms (wait time for retransmission if ACK is not received) Sending failure rate 5% (Due to the inherent characteristics of the PLC channel, information transmission may fail; therefore, a 5% packet loss rate is allowed.) Node damage rate 0.5% (This is a lower value taken based on engineering practice, assuming no node damage occurred during the test)

[0013] Because the routing algorithm used is based on the channel conditions between nodes and introduces a node caching mechanism, for comparison, the selected algorithms are the traditional routing scheme (General Scheme, GS) and the SINR-based Relay Routing Algorithm (SRRA). In the former, nodes do not listen to the communication of other nodes during routing, and each node does not cache instructions. In the latter, a single node listens to communication with other nodes during routing, but each node does not cache instructions. Ten nodes at the last layer were selected to test the end-to-end latency. Simulation results are as follows. Figure 3As shown in the simulation results, the proposed RCRS algorithm significantly reduces end-to-end latency compared to the comparison algorithms GS and SRRA. Comparing SRRA, RCRS, and GS, it can be found that during routing, relay nodes acquiring channel information with other nodes and selecting the optimal node is beneficial for reducing end-to-end latency. For example, at node 4, compared to the GS algorithm, SRRA and RCRS reduce end-to-end latency by 58% and 68%, respectively. Comparing RCRS and SRRA, it is found that temporarily caching instructions at relay nodes can further reduce end-to-end latency. For example, at nodes 5 and 6, the proposed RCRS algorithm saves 20% and 25% latency compared to the SRRA algorithm, respectively.

[0014] To test the algorithm's reliability and investigate the impact of network environment on node data reception latency, the inter-node connectivity rate was modified to simulate changes in network conditions. A lower connectivity rate indicates a worse network environment, and vice versa. Therefore, the inter-node connectivity rate was reduced from 80% to 10% to simulate a deteriorating network environment. The average end-to-end latency of the last-layer nodes was tested, and the results were obtained by averaging 500 simulations. The simulation results are as follows: Figure 4 As shown in the simulation results, compared to algorithms incorporating inter-node monitoring, the end-to-end latency of the GS algorithm increases with decreasing inter-node connectivity, while the SRRA and RCRS algorithms remain almost unchanged. This is because this section uses inter-node connectivity to characterize the quality of the network environment. When the node connectivity decreases, it means the network environment deteriorates, and the performance of the GS algorithm will decrease accordingly. However, SRRA and RCRS perform routing based on the inter-node status, so they are almost unaffected and have higher reliability. Furthermore, the proposed RCRS algorithm can save an average of 21% latency compared to the SRRA algorithm.

Claims

1. A routing optimization method for PLC-based navigation lighting control based on relay buffering, wherein in order to obtain an effective relay route and formulate a suitable relay routing table, the CCO needs to obtain the channel conditions between nodes and use its computing power to calculate a suitable relay route; characterized in that: The steps are as follows: Step 1: Create a Layer 1 local trunk routing table and send an ACK command and the Layer 1 local trunk routing table back to the CCO. Step 2: Obtain the initial global relay routing table, and the CCO sends the optimal route to the first-layer PCO. Step 3: Cache the route path selected by the CCO, and use the path to send the cached control commands to other nodes. Then, form a second-layer relay routing table and send back an ACK command and a second-layer local relay routing table to the CCO. Step 4: Update the global relay routing table and send the optimal route to the Layer 2 PCO; Step 5: The second-layer PCO repeats step 3 and sends back the third-layer local routing table; Step six: The CCO repeats step four, selects the third-layer PCO, and sends the optimal route path to the third-layer PCO based on the previously selected optimal route path. Step 7: Repeat steps 3 and 4 until the fourth layer of PCO is established; Step 8: The CCO and PCO cache the optimal routing path for the next control command to be sent.

2. The routing optimization method for PLC-based navigation lighting control based on relay buffering as described in claim 1, characterized in that: The navigation light transmission model is abstracted as shown in Figure 1, where the transmitting end is the CCO, and there are [missing information] in the entire loop. One load, representing Each node has a navigation light; this model deploys a relay device at each node, and each relay device is configured to have a certain computing power and support instruction caching. Instructions generally only include time and on / off status, so small-capacity caching is feasible; in addition, the CCO selects appropriate nodes to enable the relay function based on the real-time channel conditions of the network.

3. The routing optimization method for PLC-based navigation lighting control based on relay buffering as described in claim 1, characterized in that: The first step involves the CCO broadcasting control commands to all nodes, which are then listened to by all nodes. All nodes that receive the commands will cache them. Each node will then form a first-level local relay routing table based on the channel conditions of other nodes it has been listening to, and send back an ACK command and the first-level local relay routing table to the CCO.

4. The routing optimization method for PLC-based navigation lighting control based on relay buffering as described in claim 1, characterized in that: Step two involves the CCO reading the relay routing table returned by the nodes that can communicate directly. By comparing the channel state information of each node with other nodes, a suitable node is selected as a relay node (these relay nodes are called the first-layer PCOs) to obtain the initial global relay routing table. Then, the CCO sends the optimal routing path to the first-layer PCO in order to select the best channel conditions to send control commands to the nodes that the first-layer PCO can communicate with.

5. The routing optimization method for PLC-based navigation lighting control based on relay buffering as described in claim 1, characterized in that: Step 3 specifically involves the first-layer PCO receiving the CCO instruction, caching the route path selected by the CCO, and using this path to send the cached control instruction to other nodes (this control instruction does not need to include the control instruction of the sending node); after receiving the control instruction, other nodes form a second-layer relay routing table based on the channel conditions of the remaining nodes they have monitored, and send back the ACK instruction and the second-layer local relay routing table to the CCO.

6. The routing optimization method for PLC-based navigation lighting control based on relay buffering as described in claim 1, characterized in that: Step four specifically involves the CCO reading the Layer 2 local relay routing table, comparing the channel state information of each node with other nodes, selecting suitable nodes as relay nodes (these relay nodes are called Layer 2 PCOs), and updating the global relay routing table; then the CCO sends the optimal route to the Layer 2 PCO through the path of the Layer 1.

7. The routing optimization method for PLC-based navigation lighting control based on relay buffering as described in claim 1, characterized in that: In step seven, if a node still has not received a control command or sent an ACK instruction after the fourth-layer PCO has been established, then that node is considered to be faulty.

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