With the continuous development of semiconductor lighting, the demand for LED street lamps in energy monitoring is more prominent, requiring LED street lamp energy monitoring to form a relatively complete network system. Therefore, it is required to realize the formation and reliable transmission of the network on the basis of remote control. In the continuous development of communication technology, low-voltage distribution networks have been widely used in telecommunications. "The last mile access network" is an ideal communication medium to replace the private network; Power Line Communication (PLC) is also called power carrier communication. It is a technology that uses power lines to transmit analog or digital signals through carrier waves. It has become an important way of modern digital communication. The implementation of LED street light energy monitoring network is mainly composed of two parts. The first part is to realize remote monitoring. The GSM or GPRS network can be used for remote monitoring. The second part uses the power line for communication when collecting and controlling the terminal LED street light.
For GSM and GPRS technologies, there are mature communication devices in the process of network communication, but due to the structural complexity of the low-voltage distribution network, the transmission of high-frequency signals on the low-voltage network will inevitably have a large attenuation, making the signal of the low-voltage power line channel The attenuation is large and the noise interference is strong, which seriously reduces the reliability of the PLC channel. To this end, find an effective low-voltage distribution network power line communication automatic networking and rapid network recovery and improve its invulnerability method and power line communication reliability, expand the scale of application.
This paper mainly studies the power line communication network in the LED street light energy monitoring network. Combined with the specific characteristics of power line communication, the ant colony algorithm is used to search the optimal path of power line communication in the unknown physical topology environment, and the self-healing ability of the power line network is improved. An effective method to realize network reconstruction and improve reliability of power line communication.
2LED street light energy monitoring network features Due to the time-varying, frequency selective and strong interference characteristics of the power line carrier communication channel in the LED street light energy monitoring network, the power carrier communication network must have certain characteristics: due to LED street light energy monitoring Network physical and logical topologies change frequently. These changes have made the power line communication networking in the LED street light energy monitoring network have many similarities with the Adhoc network. Therefore, the power line communication method in the LED street lamp energy monitoring network can neither guarantee the communication distance nor ensure the reliability of the long-term operation of the power line communication system.
There are no dedicated switches or repeaters. As the power line communication for the LED street lamp energy monitoring network, devices such as dedicated switches and repeaters in the Internet network are generally not used, and signal forwarding and amplification cannot be realized. Therefore, the communication distance will dynamically change as the quality of the grid channel changes.
The communication medium shares the channel. In the process of power line communication of LED street light energy monitoring network, under one power supply transformer, the power line carrier channel is completely shared, the information is broadcasted, and all power line carrier nodes (hereinafter referred to as nodes) share the same channel. In this environment, the inherent characteristics of the channel characteristics of the low-voltage distribution network cannot guarantee that each carrier node can correctly receive relevant information. Therefore, the power line communication network in the LED street light energy monitoring network needs to divide the same physical subnet into multiple logical subnets through routing/repeaters.
Weak Data Processing Capability LED street light energy monitoring network generally consists of a central (core) node, multiple master nodes and several terminal device nodes. The central node and the master node are generally centralized controllers, and the CPU data processing capability included is relatively strong; and the terminal devices are mostly WD street light energy collectors, or do not contain a CPU, or the CPU data processing capability included is weak. Power line communication modules generally use CPUs with weak data processing capabilities. Therefore, power line communication networks are difficult to implement using network routing algorithms in general computer networks.
―Multi-communication. In the LED streetlight energy monitoring network, the communication method is often "one-to-many", that is, a centralized controller (central node) communicates with several LED streetlight energy collection terminal devices (terminal nodes) that it is responsible for controlling, each No direct command issuance (communication) between terminal devices. Therefore, only one global routing table needs to be maintained, that is, only the central node needs to ensure reliable communication with all terminal nodes, which greatly simplifies the maintenance of the power line communication routing table.
3 LED street lamp monitoring network based on ant colony algorithm 3.1 The basic principle of ant colony algorithm is a parallel optimization algorithm developed in recent years and inspired by natural ants searching for food behavior. The algorithm is a kind of heuristic stochastic optimization algorithm with excellent performance. The positive feedback mechanism is used to achieve distributed global optimization. The pheromone is continuously updated to finally converge on the optimal path. The algorithm does not need to perform a large number of probability calculations or build complex The mathematical model is used for system prediction, which can be applied to the combined optimization solution of routing in the LED street light energy monitoring communication network, which can greatly improve the reliability and robustness of the system.
3.2 The ant colony theory based network routing algorithm has a set C of nodes; the number of ants is w, used to avoid the residual information of the residual pheromone caused by the amount of information to flood the heuristic information, each ant walks one step or traverses After the "nodes", the residual pheromone is updated. The pheromone on the path M at time H is adjusted according to the following rules: -p indicates the pheromone volatilization coefficient, in order to prevent the wireless accumulation of information, the value of p The range is (0,1); indicates the pheromone increment on the path (i) in this cycle, the initial time Ati; /=0, the table is not A: only the ant stays in the path in this cycle (to) The amount of pheromone on the final. Finally, the final pheromone update is completed by different update strategies.
The power line network topology in the LED street light energy monitoring network is regarded as a graph composed of nodes and links, G (F, Fantasy F is a set of nodes, and five is a set of edges. The distance represents the minimum hop count between two nodes) The existence of direct communication between nodes is a hop node, and the distance of communication when passing through a router is increased to 1 hop.
4 The simulation result is to verify the validity of the algorithm, and establish a network topology identical to the actual system, that is, a star network consisting of 4 branches, each node has 16 nodes, and the central node is node 1, and it is assumed that each The nodes can cover the next 6 nodes as far as possible. Each ant has a maximum lifespan of 5 hops. A Matlab simulation result of 20 ants for each iteration and route search for node 65. It searches out node 25 and node 49 or node 25 and node 45. It can be seen that the best route is not unique, which is also consistent with the actual situation.
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