Research on Controllable networking methods based on ZigBee Wireless Networks (1)

Research on Controllable networking methods based on ZigBee Wireless Networks (1)

ZigBee wireless network application nodes mostly use self-networking to access the network, which may cause excessive consumption of some nodes in the network. In this case, a controllable networking mode is proposed. By selecting and controlling the parent node of a node to access the network, the topology and Node Distribution of the entire network can be effectively monitored and managed, and the life of nodes and networks can be extended. The feasibility is verified by compiling and implementing the controllable Networking Mode in the Development System Based on.

With the development of society, wireless networks play an increasingly important role in our activities. There are many wireless communication technologies, among which ZigBee technology is suitable for some specific requirements such as smart home, smart building, medical applications and industrial automation due to its low speed, short distance, and low power consumption.

This article mainly studies the ZigBee network communication networking mode. Nodes in the ZigBee network specified in ZigBee2007/PRO adopt wireless self-networking to form a network. In the self-built network, multiple sub-nodes are easily connected to the same parent node, resulting in excessive load on some routing nodes and fast power consumption, leading to premature death. This article mainly studies a controllable networking method that allows users to automatically or manually select the parent node through the upper computer to allow the node to access the network, so as to avoid excessive consumption of individual key nodes, extend network life.

1 Wireless Self-networking Method Analysis

Ad Hoc, also known as multi-hop wireless networks, is a self-organizing technology with no central nodes and multiple hops. In the networking mode proposed in ZigBee2007/PRO, a new node can be randomly placed in the network. After the power is turned on, the node Initialization is completed, and then the command is sent to the coordination point first, after receiving the request allocation level command, the coordination point records the node information, assigns the corresponding level, and sends the allocation level command. If a node receives the allocation command within the specified time period, it sends a packet containing the white organization information, determines its level in the network and the parent node information, and accesses the network. If no command at the allocation level is received within the specified time period, the node will wake up from the STANDBY state, send the command at the allocation level again, and execute the command cyclically until the access is successful. When the upper limit is reached but no command information is obtained, the node fails to access and reports an error. Node self-organizing flowchart 1 is shown.

2. Improved networking

The networking method to be implemented in this article is to allow the sub-nodes to be effectively controlled throughout the process when joining the network. When a new node is placed on the network, it broadcasts and sends a beacon frame. A parent node within the valid range will receive a confirmation message, which contains the information of the parent node, after receiving the feedback, the new node collects the parent node information and sends the message broadcast containing the parent node information and its own information to the Coordinator. After receiving the message, the Coordinator sends it to the host computer controller through the serial port. After judgment, the Coordinator automatically or manually selects the parent node suitable for access and sends the message to the corresponding parent node, after receiving the message, the parent node establishes a connection to send the message to the new node.

A new node is placed in the network, and the application layer first sends a Discovery Network request primitive NLME-NETWORK-DISCOVERY.request to the network layer to initialize the node after the power is turned on. When the network layer receives the network discovery request primitive, it sends the node scan request primitive MLME-SCAN.request to the MAC layer to instruct the MAC layer to actively scan the network. After receiving this primitive, the MAC layer instructs the physical layer to send a scanning parent node beacon frame to the network broadcast, and then enters the standby mode for feedback. After an available parent node receives a beacon frame, it sends a confirmation message to the child node, which contains the information of the parent node. The MAC layer of the node receives each feedback beacon with a valid load, sorts the received information, and confirms the information such as the beacon load and the corresponding node address of the beacon, after finishing, the MAC layer will send an indication primitive MLME-BEACON-NOTIFY.indication to NLME. After receiving the primitive, NLME will mark the address field in the received data to determine whether it is the same as the existing address in its neighbor table. If the comparison results show that the two are the same, that is, duplicate nodes, the nodes discard the beacon. If the two are different, the nodes Save the beacon information and add the address information to their neighbor tables. The MAC layer sends a scan validation primitive MLME-SCAN.confirm to NLME after the set timing cycle is reached to mark the end of the scan process. Then the network layer sends a discovery confirmation primitive NLME-NETWORK-DISCOVERY.confirm to the application layer, and sends the node information it scans to the application layer. After receiving the discovery validation primitives sent by the network layer, the application layer sends the add request primitive NL ME-JOIN.request to the nlme, the identifier parameter corresponding to the sent primitive is consistent with the network identifier of each node found. After receiving the request instruction from the upper layer, the network layer sorts out the available parent node information, adds the address information, and sends the request primitive MLME-JOIN.request to the MAC layer. After receiving the source code, the MAC layer instructs the physical layer to send a request beacon frame to the network. Then, the node opens the timer and enters the low-power STANDBY state, waiting for the response from the superior.

The subnode will wake up at the specified interval to receive commands from the upper level. After the Coordinator completes the parent node selection, it will send a confirmation add command to the specified parent node. After the parent node receives the message, it will send a add request primitive NLME-DIRECT-JOIN.request to the child node to complete initialization, the DeviceAddress parameter in the primitive records the node address information to be added to the network, and then sends a request to the child node for the added beacon frame. After the child node receives the beacon frame of the parent node, the MAC layer sends the indication primitive MLME-ASSOICATE.in dication to the network layer and sends the received parent node information to the upper layer. After receiving the primitive, the network layer will record the parent node information and compare it with the available parent node information recorded in the neighbor table is consistent, if consistent, then send to the MAC layer to add request primitive MLME-JOIN.request; if they are inconsistent, an error report is sent. After the MAC layer is successfully associated with the parent node, it sends the Add validation primitive MLME-JOIN.confirm to the network layer to indicate that the addition was successful, and the network layer sends the Add validation primitive NLME-JOIN.confirm to the application layer to inform the node of successful inbound. Figure 2 shows the information flow chart for adding a new node to a network subnode.

As the coordination point of the parent node or after the routing node receives the node scanning beacon frame sent by the child node, the NLME will first check whether its neighbor table has matched address information, to determine whether the new node has been added to the network. If matched address information is found, the route node NLME records the address information and adds the original nodes to the network as follows; if no matching address information is found, the routing node NLME sends a response primitive MIME-ASSOCIATE.resPonse to the MAC layer. After receiving the response primitive, the MAC layer instructs the node physical layer to send a status message to the new node, which records information such as the address and identifier of the route node. When receiving the completed information frame sent by the child node, the MAC layer of the routing node will read the header address information in the Information Frame, and then send data to the NLME to send request primitive MLME-SEND.request, after receiving the request primitive, the network layer determines whether the Sending address is correct and finds the path required for sending data. After the path is established, the network layer sends the send validation primitive MLME-SEND.response to the MAC layer to instruct the node to send data. After the information is sent to the coordination point and selected by the upper computer, a command frame indicating the incoming traffic is generated and then sent. The Network forwards the command frame to the corresponding node based on the parent node address selected by the host computer. The selected parent node reads the command information after receiving the command frame, and then the node MAC layer sends the add request primitive MLME-JOIN.request to the network layer, and the NLME will assign the network address to the new node after receiving the primitive. The parent node receives the incoming request successfully, NLME will add information such as the address of the new node in the node neighbor table, and then send the Add validation primitive MLME-JOI N. confirm to the MAC layer to report the association successful. Figure 3 shows the route node information flow chart when a new node is added to the network.