Wireless network technology and its application based on ZigBee

JasonYoo

Wireless network technology and its application based on ZigBee [Copy link]

　　Abstract: ZigBee is an emerging short-distance, low-rate wireless network technology. This paper analyzes ZigBee technology, IEEE802.15.4 standard and related applications in detail, discusses their relationship and characteristics relative to other technologies, and analyzes and looks forward to its application prospects in home wireless communication networks. This paper also analyzes the combination of wireless network and NGN (IPV6).
　　Keywords: IEEE802.15.4 ZigBee short-distance wireless network IPV6

　　For a long time, the market for low-cost, low-transmission-rate, short-distance, and low-power wireless communications has existed. Since the emergence of Bluetooth, it has made industrial control, home automation, toy manufacturers and other industries excited, but the price of Bluetooth has remained high, which has seriously affected the willingness of these manufacturers to use it. Today, these industries have all participated in the IEEE802.15.4 group, which is responsible for formulating the physical layer and media access control layer of ZigBee. The IEEE802.15.4 specification is an economical, efficient, low-data-rate (<250 kbps) wireless technology that works at 2.4 GHz and 868/928 MHz for personal area networks and peer-to-peer mesh networks. It is the basis of the ZigBee application layer and network layer protocols. ZigBee is an emerging short-range, low-complexity, low-power, low-data-rate, and low-cost wireless network technology. It is a technical proposal between wireless tag technology and Bluetooth. It is mainly used for short-range wireless connections. It coordinates and communicates between thousands of tiny sensors based on the 802.15.4 standard. These sensors require very little energy to relay data from one sensor to another via radio waves, so their communication efficiency is very high.
　　Generally speaking, as the communication distance increases, the complexity of the equipment, power consumption and system cost are increasing. Compared with various existing wireless communication technologies, ZigBee technology will be the technology with the lowest power consumption and cost. At the same time, due to the low data rate and small communication range of ZigBee technology, ZigBee technology is also suitable for carrying services with small data traffic. Therefore, the main application areas predicted by the ZigBee Alliance include industrial control, consumer electronic devices, automotive automation, agricultural automation and medical equipment control.
1 Introduction to IEEE 802.15.4 and ZigBee
　　The IEEE 802.15.4 technical standard of the IEEE Wireless Personal Area Network (PAN) Working Group is the basis of ZigBee technology. The 802.15.4 standard is designed to provide low-speed connections with an effective coverage range of about 10 meters for simple devices with low energy consumption. It can be widely used in consumer and commercial applications such as interactive toys and inventory tracking and monitoring. Sensor networks are its main market targets.
1.1 802.15.4 Protocol Architecture and Technical Features
　　IEEE802.15.4 meets the Open System Interconnection (OSI) reference model of the International Standards Organization (ISO). It defines a single MAC layer and multiple physical layers (as shown in Figure 1). ZigBee Profiles
Network Application Layer
Data Link Layer
IEEE802.15.4 LLC 802.2LLC
IEEE802.15.4 MAC
868/915 PHY 2400 PHY

Figure 1 IEEE802.15.4 protocol architecture

　　The MAC layer of IEEE802.15.4 can support multiple LLC standards, and carry the IEEE802.2 Type 1 LLC standard through the SSCS (Service-Specific Convergence Sublayer) protocol, while allowing other LLC standards to directly use the MAC layer services of IEEE802.15.4. Table 1 lists the main functions of the LLC layer and MAC layer of IEEE802.15.4. Table 1 Main functions of
the LLC layer and MAC layer of IEEE802.15.4

　Main functions of the LLC sublayer: Main functions of the MAC protocol of IEEE802.15.4:

　Transmission reliability assurance and control Establishment, maintenance and termination of wireless links between devices

　Segmentation and reassembly of data packets Frame transmission and reception in confirmation mode

　Sequential transmission of data packets Channel access control

　Frame check

　Reserved time slot management

　Broadcast information management 52RD

　　IEEE802.15.4 defines two physical layer standards, namely the 2.4GHz physical layer and the 868/915MHz physical layer. They are both based on DSSS (Direct Sequence Spread Spectrum) and use the same physical layer data packet format. The difference lies in the operating frequency, modulation technology, spread spectrum code length and transmission rate. The 2.4GHz band is a globally unified ISM band that does not require application, which helps to promote ZigBee devices and reduce production costs. The 2.4GHz physical layer can provide a transmission rate of 250kbps by adopting high-order modulation technology, which helps to obtain higher throughput, smaller communication delay and shorter working cycle, thereby saving more power. 868MHz is the ISM band in Europe, and 915MHz is the ISM band in the United States. The introduction of these two bands avoids mutual interference between various wireless communication devices near 2.4GHz. The transmission rate of 868MHz is 20kb/s, and 916MHz is 40kb/s. The wireless signal propagation loss in these two frequency bands is small, so the requirements for receiver sensitivity can be reduced, and a longer effective communication distance can be obtained, so that a given area can be covered with fewer devices. Table 2 summarizes some of the characteristics of 802.15.4.
Table 2 Main technical features of IEEE802.15.4 standard

　Complexity Lower than existing standards Communication delay ≥15ms

　Purpose Only supports data communication Power consumption about 45μs

　Frequency band, data rate 868MHz:20kbps 1 MAC control method 　

　and number of signals 925MHz:40kbps 10
　2.4GHz:250kbps 16 Star network, peer-to-peer network 　

　Each network
　Supports number of nodes 65536 Addressing method 64bit IEEE address,
　8bit network address

　Connection layer structure Open Temperature -40℃～85℃

　Transmission range Indoor: 10m rate
　250kbps; +0dBmTX
　Outdoor: 30m～75m rate
　 40kbps;
　 300m rate, 20kbps Application Sensors, toys,
　control fields… 52RD

1.2 Overview of ZigBee Technology
　　ZigBee is a set of technical standards for networking, security and application software developed based on the IEEE-approved 802.15.4 wireless standard. It is more than just the name of 802.15.4. IEEE only deals with low-level MAC layer and physical layer protocols, and the ZigBee Alliance has standardized its network layer protocols and APIs. The full protocol is used for 4K bytes of basic nodes that can be directly connected to a device at a time or 32K bytes of coordinators that act as hubs or routers. Each coordinator can connect up to 255 nodes, and several coordinators can form a network, with no limit on the number of routing transmissions. The ZigBee Alliance has also developed a security layer to ensure that such portable devices do not accidentally leak their identities, and that such long-distance transmissions using the network cannot be obtained by other nodes. The
　　complete ZigBee protocol suite consists of high-level application specifications, application convergence layer, network layer, data link layer and physical layer. The protocols above the network layer are formulated by the ZigBee Alliance, and IEEE802.15.4 is responsible for the physical layer and link layer standards.
　　The application convergence layer will be mainly responsible for mapping different applications to the ZigBee network, specifically including:
　　(1) security and authentication;
　　(2) convergence of multiple service data streams;
　　(3) device discovery;
　　(4) service discovery.
　　The network layer will mainly consider adopting a network protocol based on ad hoc technology, which should include the following functions:
　　(1) General network layer functions: building and maintaining topology structures, naming and associating services, including addressing, routing and security;
　　(2) Like the IEEE802.15.4 standard, it is very power-saving;
　　(3) It has self-organization and self-maintenance functions to minimize consumer expenses and maintenance costs.
　　Compared with common wireless communication standards, the Zigbee protocol suite is compact and simple, and its specific implementation requirements are very low. The following is an estimate of the requirements for the Zigbee protocol suite:
　　(1) 8-bit processor, such as 80c51;
　　(2) The protocol suite software requires 32kbytes of ROM;
　　(3) The minimum protocol suite software requires about 4kbytes of ROM;
　　(4) The network master node needs more RAM to accommodate the device information of all nodes in the network, data packet forwarding table, device association table, security-related key storage, etc.
1.3 The entire protocol architecture
　　In terms of the division of labor in standard formulation, the ZigBee Alliance and the IEEE 802.15.4 task force jointly formulated the standard. The development of the physical layer, MAC layer, data link layer, and data encryption mechanism during transmission is led by IEEE, and they jointly discuss the development of the ZigBee Protocol Stack. In the future, they can also modify the application interface required for different applications according to the needs of system customers. ZigBee started with the 802.15.4 standard and is currently defining an application outline that allows devices manufactured by different manufacturers to communicate with each other.
1.4 IPV6 Over 802.15.4
　　The ZigBee Alliance hopes to build a wireless network that can connect every electronic device. It predicts that ZigBee will soon become a high-end wireless technology in the world, reaching 3 billion nodes by 2007. A network with billions of nodes will soon exhaust the compressed IPv4 address space, but ZigBee's routing selection does not rely on IPv6. IPv6 uses a 128-bit address length and can provide addresses almost without restriction. According to conservative estimates, IPv6 can actually allocate more than 1,000 addresses for every square meter of the entire earth. In the design process of IPv6, in addition to solving the address shortage problem once and for all, other problems that cannot be solved well in IPv4 are also considered, such as end-to-end IP connection, quality of service (QoS), security, multicast, mobility, plug-and-play, etc. Therefore, the combination of IPV6 and 802.15.4 will be the direction of future research and development. Currently, IETF is also actively formulating the Draft of V6over15.4, and its standard will be released soon.
2 Advantages and Applications of ZigBee Technology
2.1 Main Advantages of ZigBee Technology and Comparison with Bluetooth and Wi-Fi
　　IEEE 802.15.4 and ZigBee were designed from the outset to build wireless networks for devices such as thermostats, security devices and gas meters. This is determined by its main technical advantages:
　　(1) Low data transmission rate: only 10k bytes/second to 250k bytes/second, focusing on low-transmission applications.
　　(2) Low power consumption: In low-power standby mode, two ordinary No. 5 dry batteries can be used for six months to two years, eliminating the trouble of charging or frequent battery replacement. This is also the unique advantage that ZigBee supporters have always been proud of.
　　(3) Low cost: ZigBee has a low data transmission rate and a simple protocol, which greatly reduces costs. And there is no patent fee.
　　(4) Large network capacity: Each ZigBee network can support up to 255 devices.
　　(5) Short delay: Usually the delay is between 15 milliseconds and 30 milliseconds.
　　(6) Security: ZigBee provides data integrity check and authentication functions, using AES-128 encryption algorithm.
　　(7) Short effective range: The effective coverage range is between 10 and 75 meters, depending on the actual transmission power and various application modes, and can basically cover ordinary home or office environments.
　　(8) Flexible working frequency band: The used frequency bands are 2.4GHz, 868MHz (Europe) and 915MHz (USA), all of which are unlicensed bands.
　　In contrast, Bluetooth technology is basically designed as a wired alternative, often used for mobile phones and nearby headphones or PDAs. It can work for a few weeks without charging, but it cannot work for months, let alone years;
　　generally, Bluetooth devices require manual configuration and maintenance of network connections; it can be used to effectively handle 8 devices (one master device and 7 slave devices), if more, the communication rate will drop significantly.
　　802.11, also known as Wi-Fi, has similar problems. Although it is a good solution for connecting laptops and desktop computers to wired networks, its power consumption is very high.
2.2 Possible applications and market development
　　The starting point of ZigBee is to develop a low-cost wireless network that is easy to deploy. At the same time, its low power consumption will allow the product's battery to last from 6 months to several years. In the early stages of product development, it will focus on inductive networks in the industrial or enterprise markets, providing functions such as inductive identification, lighting and security control, and then gradually expand the current market to home applications. Applications that usually meet one of the following conditions can consider using ZigBee technology:
　　(1) The device cost is very low and the amount of data transmitted is very small;
　　(2) The device is very small and it is inconvenient to place a large rechargeable battery or power module;
　　(3) There is no sufficient power support and only disposable batteries can be used;
　　(4) Frequent battery replacement or repeated charging is impossible or difficult;
　　(5) A wide range of communication coverage is required. There are many devices in the network, but they are only used for monitoring or control.
　　According to the ZigBee Alliance, ordinary families can apply ZigBee to the following devices:
　　(1) Temperature controllers for air conditioning systems, automatic control of lights and curtains;
　　(2) Emergency call devices for the elderly and the disabled;
　　(3) Universal remote controls for TVs and audio equipment, wireless keyboards, mice, joysticks, and toys;
　　(4) Smoke detectors;
　　(5) Smart tags.
　　This article describes ZigBee technology and the IEEE802.15.4 standard and their related applications, discusses their relationship and advantages over other technologies, and analyzes and looks forward to their application prospects in home wireless communication networks. ZigBee technology fills the gap in the low-cost, low-power and low-speed wireless communication market. The key to its success lies in rich and convenient applications, not the technology itself. With the release of the official version of the protocol, more attention and R&D efforts will be shifted to application design and implementation, interoperability testing, and market promotion. We have reason to believe that in the near future, more and more devices with built-in ZigBee functions will enter our lives and will greatly improve our lifestyle and experience.
References
1 IEEE Standard for Information Technology-Telecommunications and information exchange
between systems-Local and metropolitan area networks-Specific Requirements-
Part15.4:Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for
Low0Rate Wieless Personal Area Networks (LR-WPANS) [S]
2 Han Xudong, Zhang Chunye, Li Peng. Sensor wireless interconnection standards and implementation. Electronic Technology Application, 2004;11
3 China ZigBee Alliance. Analysis of ZigBee Technology [S]

lqrensn

mark!Thanks for sharing.