The address of the first child node that joins the parent node is parent , and the calculation of satisfies where is the maximum number of child nodes that the parent node can load. Refer to the DAAM allocation rules, assuming that the address of the parent node is , then, the address of the th access parent node is. If the th node is the end point, the address is. ZigBee routing protocol [ 19 ] is the core technology of ZigBee.
During data transmission, a node can transmit to its parent node or child node along the tree structure according to the connection between the destination address and the current address. Assuming that the current node address is , the network depth is , and the end point address is , then, the method for judging whether the end point is a child node is as shown in. If the end node address satisfies Equation 4 , it means that the end node is the child node of the current node, and the next URL N can be calculated, as in Equation 5 : where is a parameter in DAAM allocation rules, which is the address offset of the child node.
It means the interval between coordinator and node in depth. It is the space left for the node address with depth , and the first child node to join the parent node is the parent. The address of the node is , the network depth is , and the endpoint address is. Whenever the source node of the router transmits data to the destination node, the router of the source node does not store the information of the destination node and enters the route discovery stage.
The source node writes own information and routing requirements into the system and transmits it to the entire network. When the intermediate node accepts it for the first time, it will retain the information in the packet, combine it with the address information of the previous node to form a reverse routing path from this node to the source node, and then transmit it to the broadcast. When the end node receives the information for the first time, it returns the packet to reply.
If the node is not receiving it for the first time, it will be discarded as spam. Figure 3 shows the three transmission modes of route discovery, reverse routing, and forward routing.
In the design of the ZigBee system structure, the current wired communication network of a pharmaceutical factory is improved, and the use of a wireless system can effectively solve the problem of complex wiring.
A pharmaceutical factory production workshop was used as a model, and a wireless sensor was designed to monitor the status of the workshop. Figure 4 is an overall structural diagram. First, the sensor collects the data transmitted by the field networked devices and processes the information transmitted by the router. The router is responsible for network data transmission to ensure stable and correct data transmission between various devices. The coordinator is responsible for collecting data and sending it to the host computer through the serial port.
The whole system can record and query the situation and data on site. The terminal node of the console has rich functions, can monitor the parameters of the current environment and the state of the equipment in real time, and can also set the parameters of the control system. Figure 5 is the hardware of the console. It can run bit system at the maximum clock rate. In the establishment of communication network, in the wireless sensor, the responsibility of each node is to collect, calculate, and communicate the data in the system.
Judging from the category of sensing equipment, sensors can be divided into two categories. One is a fu1l function device FFD. FFD has strong data processing capabilities and huge storage space for routing information. The other is reduce function device RFD [ 23 ]. The energy consumption of RFD is low, and the storage space is correspondingly small. Using a full function device as a system gateway is the most important and common role of RFD. Simplified functional devices are used as sensor nodes to transmit data in mobile phones and transmit them to nodes in the same network layer.
When the network coverage needs to be expanded, incorporating RFD equipment into the FFD can significantly reduce the energy consumption of the entire system. The wireless sensor network routing monitoring centre computer and many terminal devices constitute [ 24 ], and it is necessary to use a computer to automatically control multiple devices at the same time.
Therefore, the star structure network is used, and the structure diagram is shown in Figure 6. The monitoring centre includes a computer and a master node. The master node is a full-featured service device with ZigBee, whose main function is to aggregate, transmit, and communicate data from multiple child nodes.
The energy consumption of device nodes using ZigBee wireless communication technology is very low, and one AA size battery can supply energy for a period. Independent ZigBee communication equipment generally has an effective transmission distance of less than 75 meters. To expand the communication coverage, multiple nodes can be used together. In the design of equipment nodes, the support platform for wireless sensors is built by device nodes.
This kind of device node is essentially a miniature embedded system, which includes a microcontroller unit MCU [ 25 ] and MCU modules of external devices, and data collection components.
The structure of the power supply and communication components is shown in Figure 7. The responsibility of the data collection module [ 26 ] is to collect data within the specified monitoring range and can collect different data according to actual application areas, such as temperature, light intensity, and precipitation.
The MCU is responsible for the routing protocol of the control node. Its main job is to reach the requirements of the agreement and ensure the stability of the network. The power module is powered by two 1. The reserved communication interface is used, and the data collection unit is set on the end node, and it is set independently. The scalability of the equipment can be improved, and the difficulty of debugging the equipment can be reduced.
In the software structure of sensor nodes, the software structure can be divided into three layers according to the use, operating system, system service, and application management.
As shown in Figure 8 , the access entry of the components and hardware implementing the task is controlled by the operating system. Through the control of the operating system, the functions of storage management, hardware start-up, stop processing, and task adjustment can be realized. System services typically include service components and network protocol components that provide services to corresponding applications.
The nature of the system service section can be seen as an intermediate layer. From the overall analysis, node software architecture design must include communication protocols between nodes, data collection and processing of data content.
In the structure of communication protocol, from a specific direction, the network communication protocol can be seen as a two-dimensional architecture. In Figure 9 , the communication protocol structure includes the application layer, transmission layer, network layer, data connection layer, and physical layer [ 27 ].
The physical layer is responsible for providing physical channels for data transmission. In addition, the physical layer can also assist other systems to complete the channel frequency setting and energy monitoring. The data link is responsible for data frame monitoring, media contact and error control, multipath multiplexing of data flow, and building one-to-one or one-to-many stable link paths. Among them, the media access control is the most important function of the connection layer.
The radiofrequency RF module of the node is controlled by the media access protocol, which is responsible for solving the resource allocation problem of wireless communication between sensors.
Since the nodes will move, conflicts may occur between multiple nodes, and the interference of the environment will improve the error rate of the network channel of the wireless sensor. The main monitoring data of the sensor are related to energy.
Therefore, the data connection layer must design a media access control method to improve the effectiveness of energy monitoring. In the network layer control routing generation, ideally, wireless sensor networks should have on attribute address recognition function.
Moreover, the network layer should provide a way to connect with external networks such as the Internet , control system networks, etc. In data transmission and input, Figure 10 is the data transmission process. Firstly, the transmitted data should be stored in the first in and first out cache. When processing packets with uncertain scale, the length bytes appear in the first byte.
If the data size is fixed, the first byte of the first in and out cache should be the endpoint node. When valid data is stored in the first in and first out cache, synchronous bytes are sent, followed by valid loads.
Figure 11 shows the data output process. Inverse to the data transmission process, the wireless signal receives and transmits data from the line and then is processed by the hardware to achieve the exchange of data and signals. Then, data is stored in the data memory area. When the device is in the data receiving state, the preamble and synchronization bytes in the data will be detected by the mediator and the receiving device. After matching the data, the mediator will receive the payload and performs data analysis.
If the length of the data is fixed, the receiver will receive the data with reference to the default length byte. If the length of this part of the data is variable, the receiver will first save the length of the first byte record and then receive the data according to the same length.
After the match is successful, the first payload is accepted by the mediator. If the data length at this time is fixed, only the byte data of the default length will be accepted. If the data is in variable length mode at this time, the data that matches the length scale of the data will be saved. The performance of the designed and built wireless transmitter needs to be verified.
Two aspects can best reflect the performance of transmission technology, one is stability, and the other is transmission efficiency. The stability of the ZigBee wireless transmitter will be reflected by the real-time temperature during operation. If the temperature is too high, it means that the system is prone to be in an unstable state, and there is a possibility of failure at any time. We check the temperature through the node temperature monitoring data collected by the ZigBee wireless sensor network and compare it with the temperature monitoring data of the wired network sensor to analyze the stable performance of the ZigBee wireless sensor.
Under the working conditions of high load, each component is in the state of full power operation. The machine needs high voltage to ensure operation. Long-time high-voltage operation will lead to system temperature rise. At high temperature, the mechanical properties of metal decrease rapidly.
This will shorten the service life of each component, such as central processing chip, image processor, and computer graphics card. Persistent high temperatures can also lead to increased chemical performance in some specific systems, resulting in machine paralysis.
In the circuit, too high temperature will also trigger off protection, resulting in the entire system to stop working, resulting in loss of production facilities. Interfere with the transmission path by inserting obstacles in the middle of the data output device and the data receiving device. Then, the effective distance of data transmission is calculated. In the process of data transmission, whether the data is correct and whether the real-time performance can be guaranteed will determine whether the system can be used for actual automatic control.
Whether the equipment parameters of the experimental site can be collected and transported correctly is a key point that must be pay attention to.
Data accuracy is generally reflected in two aspects. One is whether the data collection of the sensor node is the same as the actual data or the error is small, and whether the accuracy can meet the accuracy requirements of industrial production; the other is whether a packet loss phenomenon occurs during wireless transmission of data. Comparing the temperature monitored by the two sensors, the data statistics of the two groups of sensors are shown in Figure By analyzing the curve data, the temperature of the traditional wired control system is higher than that of the ZigBee control system when it works.
Only in the second experiment, the ZigBee temperature is slightly higher than the wired control system. Without any internet connection, they are capable of providing end-to-end communication with the hardware. In the Consumer as well as the Industrial segment, businesses have several options for IoT protocols. At the same time, it is essential to note that each protocol has distinct features and capabilities.
Based on that, the suitability of a particular protocol is defined for a specific use case. Most of the industrial and SCADA-like supervisory control and data acquisition systems use proprietary communication protocols and fail to fulfill interoperability. Having done many projects on Consumer as well as Industrial IoT, we help you understand your project better. Data Rates- Mbps maximum, the most common is Mbps.
It is one of the most popular IoT communication protocols. This connection type works best for the LAN environment and offers fast data transfer. Capable to process large amounts of data, it is the go-to choice for many developers.
As mentioned above, based on IEEE Bluetooth is one of the most important short-range communication technologies. With reduced power consumption, this technology is a real foundation for the IoT. It is scalable and flexible to all market innovations. Like Bluetooth, there is a vast user base of ZigBee.
With a maximum number of nodes in the network, Zigbee can transfer data with a range of up to meters, ZigBee can even use bit AES encryption.
MQTT is a lightweight message protocol for sending simple data flows from sensors to applications and middleware. The MQTT protocol comprises 3 key elements: subscriber, publisher, and a broker. It proves to be a better choice for wireless networks that experience occasional bandwidth constraints or unreliable connections.
It comes under the industrial M2M communication protocol. Like MQTT, it is a platform-independent standard through which various types of systems and devices can communicate by sending request and response messages between the clients and servers. At hashstudioz, We have used it to integrate the sensor of monitoring devices for valves and their electric actuators.
Cellular IoT protocols need not pre-established gateways to create a coverage area. Though cellular networks capable of facilitating massive flows of data, cellular-enabled IoT devices use a ton of power.
Whenever there is a requirement to connect objects like the streetlights, parking meters, and hospitals or the myriad industrial applications like manufacturing and agriculture units then cellular protocols can enhance the connectivity. The infrastructural simplicity combined with the emergence of 5G makes cellular communication protocols a go-to choice. Highly preferable for home automation products such as lamp controllers, sensors among many others. Based on the mesh network topology , Z-Wave based devices can attain a communication distance of up to 40 meters, with the additional ability of messages to Hop up between up to 4 nodes.
NFC is one of the popular communication protocols these days. Hi-Low routing protocol provides an advantage of memory saving by which the networks become more scalable. DYMO-Low provides more routing delay compared to other routing protocols. To overcome the problems of conforming to current standards and ensure the accessibility of nodes sensors the 6LoWPAN protocol was designed.
Generally, these mechanisms put nodes on standby to reduce the service cycle. ZigBee defines the beacon mode that allows nodes to stay in low power mode for most of the time and periodically sends nodes a sync tag through the use of tree routing. In [4] they tried to make a comparative study between three wireless short-range wireless protocols, Bluetooth and ZigBee to deploy a wireless sensor network.
The main intention of their study is to find the most appropriate protocol applicable to wireless sensor networks. In This study analyzed 3 protocols based on a transmission time, rate of bit error, signal strength received, and packet delivery ration and energy consumption. Thus, can we conclude that ZigBee is the best protocol among the three protocols studied, ZigBee has a stable transmission time, better spectral efficiency, a higher packet transmission ratio and minimal power consumption. The results of the experimental evaluations showed that the ZigBee network is capable of handling shorter run cycles, generating maximum end-to-end delays and update times slightly below the theoretical values of 6LowPAN.
On the other hand, the 6LoWPAN network has medium end-to-end delays and higher reliability a lower percentage of packet loss. Commonly, the layers or architecture and topologies. It was created to be a standard for low-cost, high-level communication protocols and will be used in applications that require secure network devices, low data throughput, and longer battery life.
ZigBee can support different types of topologies, such as mesh, star, and tree network topologies. The architecture of the ZigBee standard is composed of 4 layers: physical, MAC, network and application as shown in Fig. ZigBee-Pro enables the transmission of large messages using fragmentation and reassembly and uses a gateway for data transfer from ZigBee nodes to the Internet. ZigBee-Pro is based on a mesh topology and not beacon mode. The main feature of this version is present in the table [7] below Table 1.
Features of ZigBee-PRO [7] Features Comments Addressing The new devices that add up to the network will automatically have an address and if two nodes have the same address, the network layer intervenes based on the MAC address of each node. Links management Each node of the mesh topology is able to communicate with its neighbor Changed channel The channel manager selects a new channel and notifies the rest of the network multiple ZigBee nodes detect overlap or noise interference Channel change Fragmentation ZigBee-Pro provides the fragmentation of larger packets into smaller ones to facilitate sending.
Power Put devices in sleep mode to consume less power When they wake up, they update Management themselves in the case of a change in the network Routing ZigBee-Pro offers two types of routing multicast and many-ta-one. ZigBee Pro network architecture [6] 3. Figure 3 shows the protocols used at each layer of the ZigBee IP architecture. It can be connected directly to another IP network without intermediate entities gateways. It supports different lengths of addresses.
It is also low bandwidth and low-cost power consumption. This gateway that is connected to the internet with the 1Pv6 domain will then forward the packet to its destination using the IP protocol.
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