A brief analysis of everything about ZigBee!

This article introduces you to all aspects in detail in the form of question and answer. It is no exaggeration to say that everything you need to know about ZigBee can be basically understood here!

In the field of intelligent hardware and the Internet of Things, nowadays the famous ZigBee can be said to be unknown to everyone. In addition to WiFi and Bluetooth, ZigBee is currently one of the most important wireless communication protocols, mainly used in fields such as the Internet of Things and smart hardware.

Chapter1 Origin History

1. What technology did ZigBee originate from?

In the process of using Bluetooth technology, people found that although Bluetooth technology has many advantages, it still has many shortcomings.

For the fields of industry, home automation control and industrial telemetry and remote control, Bluetooth technology appears to be too complex, with large power consumption, short distances, and too small networking scale. In industrial automation, the demand for wireless data communication is becoming stronger and stronger. For industrial sites, this kind of wireless data transmission must be highly reliable and able to resist various electromagnetic interferences in industrial sites.

Therefore, after long-term efforts, the ZigBee protocol officially came out in mid-2003. In addition, ZigBee uses Home RF Lite, a communication protocol for home networks that it has studied before.

2. What is ZigBee?

First of all, the Mac layer and PHY layer of ZigBee are based on the IEEE802.15.4 protocol. The technology specified in this agreement is a short-distance, low-complexity, low-power, low-data-rate, and low-cost two-way wireless communication technology. It is mainly suitable for automatic control and remote control and can be embedded in various devices. Support geolocation function.

Because bees rely on the "dance" of flying and "buzzing" (zig) their wings to communicate the location and distance of pollen with their companions, that is, the bees rely on this method to form communication in the group. "Network", so the inventors of ZigBee vividly use this behavior of bees to vividly describe this wireless information transmission technology.

3. What are the characteristics of ZigBee technology?

The characteristics of ZigBee mainly have the following aspects:

(1) Low power consumption: In low power consumption standby mode, 2 AA batteries can support 1 node to work for 6-24 months, or even longer. This is the outstanding advantage of ZigBee. In contrast, Bluetooth can work for several weeks and WiFi can work for several hours;

(2) Low cost: By greatly simplifying the protocol, the cost is very low (less than 1/10 of Bluetooth), which reduces the requirements for the communication controller. According to predictive analysis, the 8051 8-bit microcontroller is used to calculate the full-featured master Nodes need 32KB code, sub-function nodes as few as 4KB code, and the ZigBee protocol patent is free;

(3) Low rate: ZigBee works at a communication rate of 250kbps to meet the application requirements of low rate data transmission;

(4) Short distance: The transmission range is generally between 10 and 100m, after increasing the RF transmission power, it can also be increased to 1-3km. This refers to the distance between adjacent nodes. If through the relay of routing and communication between nodes, the transmission distance will be farther;

(5) Short time delay: ZigBee's response speed is relatively fast. Generally, it only takes 15ms to switch from sleep to working state, and it only takes 30ms for nodes to connect to the network, which further saves power. In comparison, Bluetooth requires 3-10s and WiFi requires 3s;

(6) High capacity: ZigBee can adopt star, flake and mesh network structure. One master node can manage several sub-nodes. At most one master node can manage 254 sub-nodes; meanwhile, the main node can also be managed by the upper network node , It can form a large network of up to 65,000 nodes;

(7) High security: ZigBee provides a three-level security mode, including no security settings, the use of access control lists (ACL) to prevent illegal access to data, and the use of symmetric passwords with advanced encryption standards (AES128) to flexibly determine its security attributes ï¼›

(8) License-free frequency band: Use the Industrial Scientific Medical (ISM) frequency band, 915MHz (USA), 868MHz (Europe), 2.4GHz (global).

Since the physical layers of the three frequency bands are not the same, their respective channel bandwidths are also different, which are 0.6MHz, 2MHz and 5MHz respectively. There are 1, 10 and 16 channels respectively. The spread spectrum and modulation methods of these three frequency bands are also different. All spread spectrum uses direct sequence spread spectrum (DSSS), but the transformation from bit to chip is quite different. The modulation methods all use phase modulation technology, but the 868MHz and 915MHz frequency bands use BPSK, and the 2.4GHz frequency band uses OQPSK.

When the transmit power is 0dBm, Bluetooth usually has a range of 10 meters. The ZigBee can usually reach a range of 30-50 meters indoors, and even 400 meters in open areas outdoors (TI CC2530 does not add power amplification).

Therefore, ZigBee can be classified as a low-speed short-range wireless communication technology.

4. Why is ZigBee produced in response to the increasing demand for reliable wireless data transmission in industrial automation?

ZigBee technology itself is produced because Bluetooth technology cannot meet the requirements for low data volume, low cost, low power consumption, and high reliability wireless data communication in industrial automation. Because, for industrial sites, this wireless data transmission must be highly reliable and able to resist various electromagnetic interferences in industrial sites.

In ZigBee technology, a mesh network topology, automatic routing, dynamic networking, and direct sequence spread spectrum are used. Just to meet this need of industrial automation control site.

Chapter2 Communication Technology

1. What kind of protocol does ZigBee use?

IEEE802.15.4 protocol, which is an unlimited PAN protocol with a low transfer rate. In terms of standardization, the IEEE802.15.4 working group is mainly responsible for the formulation of physical layer and MAC layer protocols. The remaining protocols mainly refer to and adopt existing standards. The ZigBee Alliance will be responsible for high-level applications, testing and marketing.

2. Why is the 2.4G frequency band used for ZigBee wireless communication free?

In my country and most other countries in the world, the general use of radio equipment is to pay frequency usage fees, including mobile phone communications, but the mobile operator has already paid this fee to the country and paid the user through number occupancy fees. This fee was charged.

When using other wireless devices, you must first apply for a frequency use license from the relevant national authorities, and then charge a fee based on the frequency, power, and quantity used by your wireless device. This is not a small expense. Generally, equipment costs several thousand yuan a year.

The free frequency band refers to a frequency band allocated by each country according to their actual conditions and considering as much as possible consistency with other countries in the world, specifically for industrial, medical and scientific research use (ISM frequency band). Bands that can be used free of charge upon application.

The 2.4G frequency band in our country is just such a frequency band. However, in order to ensure that everyone can use it reasonably, the state has made corresponding restrictions on the power of wireless transceiver equipment in this frequency band under different environments. For example, in an urban environment, the transmit power cannot exceed 100mW.

3. Is ZigBee only suitable for short-distance communication?

The ZigBee local area network can not only expand the network by increasing the transmit power and receiving sensitivity of each node module, and increase the number of nodes, but also can monitor the remote ZigBee control network through the traditional Internet. However, what should be paid attention to when expanding is:

(1) As the transmission power increases, the power consumption will naturally increase. If the power consumption is also large, it will lose the advantage of ZigBee's own low power consumption;

(2) Although 2.4Ghz is a free frequency band, it cannot exceed the maximum power limit in the radio law.

4. What are the advantages of ZigBee's direct sequence spread spectrum communication method?

The same frequency band, using different communication methods may have very different results, such as ASK, FSK, FHSS, DSSS, etc. anti-jamming capabilities, communication security, confidentiality, and reliability are all different. The ZigBee system, like the CDMA system, uses Direct Sequence Spread Spectrum (DSSS), which is a communication method with strong anti-interference ability, high confidentiality and reliability. If you have used communication products of these two technologies, you will find that the two are different in reliability.

Since the signal-to-noise ratio required by the spread spectrum technology in normal communication can be very low, that is to say, it can still work normally in an environment with strong interference. According to calculations and experiments, this is equivalent to an increase in receiving sensitivity of 7dBm. It is also not easy to interfere with others. In other words, it can use lower power to transmit longer distances. Some materials related to the superiority of spread spectrum technology are quoted below for reference:

CDMA is a new type of digital cellular technology introduced in 1995 after the introduction of digital communication technology in the world. It uses digital transmission methods and spread spectrum communication technology to greatly improve the frequency utilization rate. It has large capacity and coverage. The outstanding advantages of broadband, low power consumption of mobile phones and high voice quality have pushed mobile communication technology to a new stage of development. Compared with FDMA (Frequency Division Multiple Access) and TDMA (Time Division Multiple Access) systems, CDMA (Code Division Multiple Access) cellular systems have the following outstanding advantages:

(1) Good anti-interference performance. Because CDMA has undergone spread spectrum processing, it has good anti-interference performance and can coexist with narrowbands in the same frequency band without affecting its normal operation.

(2) The ability to resist multipath fading is strong. Multipath fading is a prominent problem that affects the quality of mobile communications. It is usually necessary to adopt spatial diversity, adaptive equalization and other technologies to overcome it, and there is a large fading margin. The CDMA system can use multipath signals to provide path diversity, which not only eases Rayleigh fading, but also eases the slow fading caused by physical obstruction, thereby greatly improving the high communication quality of Qualcomm.html' target='_blank'.

(3) Increased system capacity For FDMA and TDMA, once the frequency or time slot of the cell is allocated, the cell cannot receive new calls, and the capacity has a hard limit. However, CDMA is an interference-limited system. Under a specified interference level, even when the number of users has reached a limited number, it still allows individual users to be added. The disadvantage is that the voice quality is reduced. Service providers can balance between capacity and voice quality. CDMA's precise power control and soft handoff technology greatly reduces the strength of the interference signal and the required signal-to-noise ratio requirements, and it effectively uses voice activation or variable rate voice coding, diversity reception, and power control. According to reports, the CDMA signal-to-noise ratio is 3.7 times that of DAMPS and TDMA, 11.2 times that of TACS, 13.6 times that of AMPS, and 20 times that of FM/FDMA.

(4) Good communication quality CDMA system adopts direct sequence spread spectrum technology, comprehensive application of time diversity, frequency diversity, space diversity, path diversity and other diversity technologies to overcome multipath effects and obtain strong anti-interference ability. During the handover, the soft handover technology that is established first and then interrupted is adopted to ensure the communication quality of CDMA, and there is no ping-pong effect especially during the handover. This system is broadband and low-noise ratio, the waveform allows the use of high-redundancy error correction coding and high-efficiency digital modulation technology to ensure high-quality voice and data transmission.

(5) High frequency utilization The same frequency of the CDMA system can be reused in all cells, and its frequency reuse rate is 2/3 (FDMA and TDMA frequency reuse rate 1/7), without FDMA and TDMA Performing frequency configuration in that way greatly simplifies cell splitting and the introduction of microcells.

(6) Strong multiple access capability The multiple access capability of the CDMA system determines the size of the multiple access interference between spreading codes. It is related to the spreading coding scheme used, and is related to the multiple access interference between users sending signals at the same time (that is, the spreading coded Related characteristics) It is related to the allowable reception quality (output signal-to-noise ratio). Therefore, the lower the multiple access interference between users working at the same time, the lower the allowable reception quality, and the stronger the multiple access capability of the CDMA technology.

(7) Highly reliable confidentiality and security CDMA mobile communication system is a confidential communication system. If a certain encryption algorithm technology is added, the communication security performance can be greatly improved, which is unmatched by FDMA and TDMA systems. Analyzing the spread spectrum system it adopts, it is almost impossible to intercept the communication content of others. For example, as long as the lithium battery in the machine is not discharged, it changes the real-time state of the sequence at a clock frequency of 512KHz, even if it is continuously working , Its spread spectrum address sequence cycle is as long as 7 years. It can also easily set and change the master key, sub key, spread spectrum code table, standard encryption algorithm, etc. in the CDMA system, making the communication confidentiality more reliable.

(8) Low power consumption of mobile phones After CDMA adopts power control, the transmit power level is increased only during the fading period, so that the average transmit power is reduced. The minimum power of FDMA is 5mW, the average transmit power is 794 mW, and the peak power is 3W. , And the minimum power of CDMA is 2.3mW, the average transmit power is 5 mW, and the peak power is 100mW. It can be seen that the average transmit power and maximum transmit power of CDMA are lower than FDMA, which increases the system capacity, reduces the number of cells and reduces equipment costs.

5. What are the characteristics of ZigBee compared with existing digital radio stations?

The advantages are as follows:

(1) High reliability: Because the ZigBee module has a much higher integration level than the general data transmission station, and there are fewer separate components, the reliability is higher;

(2) Convenient and safe to use: Because of the high integration level, compared with the general data transmission radio, the ZigBee receiving module can be made small in size, and has low power consumption. The maximum transmission current is much smaller than that of a CDMA mobile phone. Easy to integrate or put directly in the equipment, not only convenient to use, but also not easy to be damaged when carried and used outdoors;

(3) Strong anti-interference ability, good confidentiality, and low bit error rate: The ZigBee transceiver module uses 2.4G direct sequence spread spectrum technology, which is better than general FSK, ASK and frequency hopping digital transmission radio stations. Anti-interference ability, and longer transmission distance;

(4) Free frequency bands: ZigBee uses free frequency bands, and the frequency bands used by many digital radio stations not only need to apply, but also need to pay a considerable frequency usage fee to the National Committee of the People's Republic of China every year;

(5) Low price: The price of ZigBee digital transmission module is only a fraction of that of digital transmission radio with similar functions.

6. Why is the anti-interference performance of ZIGBEE higher than Wi-Fi and Bluetooth technology?

After recent research on ZigBee technology and related test practices, MORLAB has summarized the following points, which are also the main reasons for the strong anti-interference ability of ZigBee products.

ZigBee's anti-interference characteristics are mainly anti-co-channel interference, that is, interference from other technologies sharing the same frequency band. The main features are as follows:

1. Clear Channel Assessment (CCA):

Determine whether the channel is free. The IEEE 802.15.4 physical layer provides CCA capability in the collision avoidance mechanism, that is, if the channel is occupied by other devices, the transmission is allowed to exit without considering the communication protocol using the channel.

There are currently three types of idle channel assessment modes:

(1) Judge the signal energy of the channel. If the signal energy is lower than a certain threshold, the channel is considered idle;

(2) Judge the characteristics of the wireless channel, which mainly includes two aspects, namely spread spectrum signal and carrier frequency;

(3) Integrate the first two modes, detect signal strength and signal characteristics at the same time, and give a channel idle judgment.

2. Dynamic channel selection:

The coordinator in the ZigBee Personal Area Network (PAN) (the central node of the network, responsible for the organization and maintenance of the network). First scan all channels, then confirm and add a suitable PAN (no need to create a new PAN), reduce the number of PANs in the same frequency band, and reduce potential interference. If the interference source appears on the overlapping channel, the upper layer software of the coordinator should apply the channel algorithm to select a new channel.

3. Channel algorithm:

When the network is initialized or in response to an interruption, the ZigBee device will first scan a series of channels listed in the channel table parameters for dynamic channel selection, and set the channel table parameters according to the above idle channels to enhance the coexistence performance of the network.

During severe interference, ZigBee does not change the channel, but relies on its low duty cycle, collision-free algorithm (each device listens to the channel before sending data) to reduce data loss due to transmission conflicts.

4. Direct sequence spread spectrum technology (DSSS) and fast frequency change FA:

Direct sequence spread spectrum technology has a certain anti-interference effect (as shown in the figure below). Under other conditions, the transmission distance is longer than frequency hopping technology (when the transmit power is 0dBm, Bluetooth has a 10m range, while ZigBee is indoors. It can reach the range of 30-50m). The so-called rapid frequency change is to change the frequency to avoid the influence of a known interference source or signal source.

As can be seen from the above figure, ZigBee's bit error rate can reach 10-9 when the signal-to-noise ratio is 4dB. To achieve the same bit error rate, Wi-Fi must reach 10dB, Bluetooth up to 16dB, and ZIGBEE's anti-interference performance is significantly higher. Based on Wi-Fi and Bluetooth technology.

5. Response retransmission and frame buffering:

The MAC layer and application layer (APS part) of ZigBee have the functions of automatically requesting retransmission of ARQ and frame buffering. When transmitting a data frame to the device, if the receiving device is in a busy or dormant state and cannot receive the frame, the main coordination device of the network temporarily buffers the frame until the receiving end receives the frame.

Although the modulation method is very simple, ZigBee has shown good anti-interference performance in the 2.4GHz ISM frequency band, which is very suitable for applications with low power consumption and low data transmission. At present, the test standard adopted by ZiBee products in CE certification is EN300328, while in FCC, Part 15C test is mainly adopted.

Chapter3 Network Technology

1. What kind of wireless data transmission network does ZigBee have?

Simply put, ZigBee is a highly reliable wireless data transmission network, similar to CDMA and GSM networks, and the ZigBee data transmission module is similar to a mobile network base station. The communication distance ranges from the standard 75 meters to several hundred meters and several kilometers, and it supports wireless expansion.

ZigBee is a wireless data transmission network platform composed of up to 65,000 wireless data transmission modules. It is very similar to the existing mobile communication CDMA network or GSM network. Each ZigBee network data transmission module is similar to a base station of the mobile network. Within the entire network, they can communicate with each other; the distance between each network node can range from the standard 75 meters to the extended hundreds of meters, or even several kilometers.

Different from CDMA network or GSM network of mobile communication, ZigBee network is mainly established for industrial field automation control data transmission. Therefore, it must be simple, easy to use, reliable in work, and low in price. The mobile communication network is mainly established for voice communication, and the value of each base station is generally more than one million yuan, while each ZigBee "base station" is less than 1,000 yuan.

Each ZigBee network node can not only be used as a monitoring object, for example, the connected sensors can directly collect and monitor data, but also can automatically transfer data from other network nodes. In addition, each ZigBee network node (FFD) can also be wirelessly connected to multiple isolated sub-nodes (RFD) that do not undertake the task of network information transfer within its own signal coverage.

Each ZigBee network node (FFD and RFD) can support up to 31 sensors and controlled devices, and each sensor and controlled device can eventually have 8 different interface modes. It can collect and transmit digital and analog quantities.

2. What is the self-organizing network used by ZigBee?

A simple example can illustrate this problem. When a team of paratroopers are airborne, each holds a ZigBee network module terminal. After landing on the ground, as long as they are within the communication range of the network module, they can automatically find each other. An interconnected ZigBee network can be formed soon. Due to the movement of people, the communication between each other will also change. Therefore, the module can also refresh the original network by re-searching the communication partner, confirming the contact between each other. This is the self-organizing network.

3. Why does ZigBee technology use ad hoc networks to communicate?

Mesh network communication is actually multi-channel communication. In the actual industrial site, due to various reasons, it is often impossible to guarantee that every wireless channel can always be unblocked. Just like a city street, it may be caused by car accidents, road maintenance, etc. Traffic on a certain road is temporarily interrupted. At this time, because we have multiple channels, vehicles (equivalent to our control data) can still reach the destination through other roads. This is very important for industrial field control.

4. Why should the ad hoc network adopt dynamic routing?

The so-called dynamic routing means that the path of data transmission in the network is not preset, but before transmitting data, by searching all the paths available on the network at the time, analyzing their positional relationship and distance, and then selecting one of the paths Perform data transfer.

In our network management software, the path selection uses the "gradient method", that is, the nearest channel of the path is selected for transmission. If the transmission fails, another channel a little further away is used for transmission, and so on. Until the data reaches the destination.

In the actual industrial site, the predetermined transmission path may change at any time, or the path may be interrupted due to various reasons, or it may be too busy for timely transmission. Dynamic routing combined with mesh network topology can solve this problem well, thereby ensuring reliable data transmission.

1. What are the characteristics of ZigBee compared with the existing communication mobile network (GPRS, CDMA-1X)?

Its characteristics are:

(1) No network usage fee: long-term network usage fee is required to use the mobile network, and it is calculated according to the number of node terminals, but ZigBee does not have this fee;

(2) Equipment investment is low: the use of mobile network requires the purchase of mobile terminal equipment, the price of each terminal is around RMB 1,000, and the use of ZigBee network, not only the cost of the ZigBee network node module (equivalent to base station) is less than RMB 1,000 per unit And, the price of the main network sub-node (equivalent to a mobile phone) is much lower;

(3) Communication is more reliable: Since the existing mobile network is mainly designed for mobile phone communication, although CDMA-1X and GPRS can carry out data communication, it has been found in practice that not only the communication rate is much lower than the designed rate, but also the data communication is reliable. Trust and continuity cannot be guaranteed in many cases. The ZigBee network is specially designed for the transmission of control data, so the transmission of control data has considerable guarantee;

(4) High flexibility and low cost: First, by using ZigBee network nodes with different coverage distances and different functions, and other low-cost wireless transceiver modules of non-ZigBee systems, a ZigBee local automation control network is established, and then through The Internet or mobile network is connected to a remote computer to realize low-cost and high-efficiency industrial automation telemetry and remote control;

(5) Compared with the existing mobile communication network, although ZigBee is only a local area network, by providing enough data exports, it can expand its coverage "infinitely", and can be integrated with the existing mobile network, Internet and Other communication networks are connected. And through these networks, many ZigBee LANs are connected to each other into a whole. Effectively solve the problem of blind area coverage of mobile networks: We know that existing mobile networks have blind areas in many places, especially in the fields such as railways, highways, oil fields, and mines. The cost of adding a mobile base station or repeater is considerable. At this time, using the ZigBee network to cover the blind area is not only economical and effective, but is often the only feasible method now.

6. How does ZigBee realize long-distance telemetry and remote control?

The ZigBee network can also be connected to the Internet, GPRS network, CDMA1x network and other communication system lines through interface cards and other ways to realize remote control. You can also connect two or more local ZigBee networks together through other networks.

Chapter4 Market Application

1. What are the application areas of ZigBee technology?

The goal of ZigBee technology is to target industrial, home automation, telemetry and remote control, such as lighting automation control, wireless data acquisition and monitoring of sensors, oil fields, power, mining and logistics management and other application fields.

2. What industrial site requirements for wireless data transmission have been implemented by ZigBee?

Requires low power consumption, low data volume (250KPS), low cost, free ISM frequency band (2.4G), direct sequence spread spectrum communication (DSSS) with high anti-interference performance, high confidentiality (64-bit factory number and Support AES-128 encryption), high integration and high reliability;

The node modules have the function of automatic and dynamic networking, adopting the topology structure including mesh network, using the collision avoidance mechanism, and the information is transmitted through automatic routing in the entire ZigBee network, thus ensuring the information transmission reliability.

3. In what areas can ZigBee expand its application?

ZigBee application: Its range is very wide, and it can be aimed at application fields such as industrial automation, home automation, telemetry and remote control, automobile automation, agricultural automation and medical care, oil field, electric power, mining and logistics management.

Examples of practical applications are as follows: lighting control, environmental control, automatic meter reading systems, various curtain controls, smoke sensors, medical monitoring systems, large air-conditioning systems, set-top boxes with built-in home control and universal remote controls, heating control, home security, industrial and Building automation. In addition, it can also locate moving targets in a local area, such as vehicles in cities.

4. What kind of short-distance communication can be considered for ZigBee technology?

Generally, ZigBee can be considered for short-distance communication that meets one of the following conditions:

(1) There are many outlets that need data collection or monitoring;

(2) The amount of data required to be transmitted is not large, but the cost of equipment is low;

(3) High reliability and high security of data transmission are required;

(4) The equipment is required to be small in size, and it is inconvenient to place large rechargeable batteries or power modules;

(5) It can be powered by batteries;

(6) The terrain is complex, there are many monitoring points, and larger network coverage is required;

(7) Cover the blind areas of existing mobile networks;

(8) The existing mobile network has been used for low data transmission telemetry and remote control system.

5. What is the application situation of ZigBee technology in my country?

Although many people in China have begun to pay attention to this new technology of ZigBee, and many companies have begun to get involved in the development of ZigBee technology, however, considering that ZigBee itself is a new system integration technology, the development of application software must be transmitted over the network. The radio frequency technology is combined with the underlying software and hardware control technology, so it has certain technical difficulties for the initial development enterprises. Due to various constraints, the large-scale commercial application of ZigBee technology will take time.

However, it has already demonstrated extraordinary application value, and I believe that with the development and advancement of related technologies, it will definitely get even greater applications. However, we should also clearly realize that wireless networks based on ZigBee technology have just begun to develop, and its technology and applications are far from mature. Domestic companies should seize business opportunities, increase investment, and promote the entire industry. development of.

Five, ZigBee Alliance

1. What is the mission of the ZigBee Alliance?

The ZigBee Alliance is a fast-growing non-profit industry organization with members including internationally renowned semiconductor manufacturers, technology providers, technology integrators and end users. The alliance has formulated a network application specification based on IEEE802.15.4 with high reliability, high cost performance, and low power consumption.

2. What is the goal of the ZigBee Alliance?

The main goal of the ZigBee Alliance is to provide consumers with more flexible and easier-to-use electronic products by adding wireless network functions. ZigBee technology can be integrated into various electronic products, and its application scope spans the global civil, commercial, public utility and industrial markets. This allows alliance members to use ZigBee, a standardized wireless network platform, to design simple, reliable, cheap and power-saving products.

3. What is the focus of the ZigBee Alliance?

Its focus is to formulate network, security and application software layers; provide coordination and interoperability test specifications for different products; promote the ZigBee brand around the world and gain market attention; and manage the development of technology.

4. What is the work done by the ZigBee Alliance on the standard?

The formulation of the ZigBee standard: the physical layer, MAC layer and data link layer of IEEE802.15.4. The standard was released in May 2003. The formulation of the ZigBee network layer, encryption layer and application description layer has also made great progress. V1.0 version has been released. Other application fields and related device descriptions will also be released one after another.

Because ZigBee is not only synonymous with 802.15.4, and IEEE only deals with low-level MAC layer and physical layer protocols, the ZigBee Alliance standardizes its network layer protocols and APIs. The full protocol is used for 4K bytes that can be directly connected to the basic node of a device at a time or 32K bytes as a coordinator of a Hub or router. Each coordinator can connect up to 255 nodes, and several coordinators can form a network, and there is no limit to the number of routing transmissions.

The ZigBee Alliance has also developed a security layer to ensure that this portable device will not accidentally leak its identification, and that this long-distance transmission using the network will not be obtained by other nodes.

The ZigBee Alliance emphasizes the interoperability of equipment: Many short-range electronic products embedded with ZigBee modules already have ZigBee functions, and many other products have reserved ZigBee interfaces for future upgrades at any time. The development of various gateway products has also been further developed. The gateway products support the interconnection of ZigBee systems with existing facilities such as home control networks, intelligent building networks, and commercial networks.

5. Who are the members of the board of directors of the ZigBee Alliance?

Sixteen companies have joined the ZigBee Alliance as a "promoter" and become members of the alliance's board of directors:

Comcast Cable (ComcastCable)

Itron Inc.

Kroger (TheKroger Co.)

Landis+Gyr

Legrand Group

Midea Group

NXP Semiconductors (NXPSemiconductors)

Philips

Schneider Electric

Silicon Labs

Samsung (SmartThings

Somfy (SOMFY)

Texas Instruments (TexasInstruments)

IOT Sensing (Wulian)

HUAWEI

LEEDARSON

6. Who are the top executives of the ZigBee Alliance?

Chairman and CEO of ZigBee Alliance: Tobin Richardson.

Chairman of the ZigBee Alliance Board of Directors: John E. Osborne II (Rieters)

Vice Chairman of the ZigBee Alliance Board of Directors:

Jean-Pierre Desbenoit (Schneider Electric)

HansDollee (NXP Semiconductor)

Musa Unmehopa (Philips Lighting)

Bruno Vulcano (Legrand Group)

David Randolph Hoelscher (Huawei)

Juston Zhu Zhu Jian (IoT Sensing) (the first Chinese vice chairman and the first Asian vice chairman)

ZigBee Alliance Financial Officer: Jean-Michel Orsat (Somfy Group)

Secretary of the ZigBee Alliance Board of Directors: Michael Koster (Samsung/SmartThings)

Chapter6 ZigBee3.0 Technology

An article in Geek Park "Why do I need to install so many apps to control my "smart appliances"? "The article aroused great repercussions in the smart home circle, directly hitting the industry pain point that the products of different manufacturers in the smart home industry cannot be interconnected.

It is written in the article that so many apps in the smart home industry cause a lot of trouble to users. If users need to use smart devices produced by different manufacturers, they must purchase smart home gateway devices from different manufacturers and use apps of different manufacturers to control the smart devices, which greatly reduces the user's enthusiasm for buying and using smart home products.

So what is the fundamental reason why smart homes cannot be interconnected? That has to start with the smart home industry chain.

1. Industrial chain and interconnection of smart home

The smart home industry chain is divided into protocol (or standard) providers, IC chip manufacturers (usually software protocol stack providers), solution providers, and smart home product providers. We mainly start with the source agreement of the smart home industry chain.

The mainstream protocols of smart home are mainly divided into: Wi-Fi, ZigBee, Z-Wave.

The Wi-Fi protocol cannot be applied to smart home devices on a large scale due to high power, relatively complex networking, and few nodes. However, due to the high transmission rate of Wi-Fi, it is very suitable for use in smart home products such as smart cameras. . Therefore, the role of the Wi-Fi protocol in the smart home is mainly as a supplementary protocol.

The Z-Wave protocol has been widely used in Europe due to its low cost, low power consumption, high reliability, short-distance wireless communication suitable for the network, and high interoperability. Z-Wave gateways can control different manufacturers based on Z-Wave Protocol equipment, but because Z-Wave is in the frequency range of 908.42MHz (U.S.) ~ 868.42MHz (Europe), the frequency band in this range belongs to the industrial frequency band in China and cannot be used by civilians, so Z-Wave protocol is almost non application.

The ZigBee protocol has become the most widely used protocol in the smart home industry by virtue of its properties such as low power consumption, mesh networking, multiple nodes, and high security. Unfortunately, the biggest problem with the ZigBee protocol is poor interoperability. Although different manufacturers use the ZigBee protocol, they cannot control each other.

2. The past and present of ZigBee

The birth of the ZigBee protocol stems from the demand for industrial Internet of Things. In order to meet different application backgrounds, the ZigBee Alliance has issued: ZigBee Home AutomaTIon (ZigBee HA), ZigBee Light Link (ZigBee LL), ZigBee Building AutomaTIon (ZigBee BA), ZigBee Retail Services (ZigBee RS), ZigBee Health Care (ZigBee HC) ), ZigBee TelecommunicaTIon services (ZigBee TS) and other application layer protocols to meet smart home, smart lighting, smart buildings, smart retail, smart health, smart communication services and other fields.

The problem is that these application layer protocols are independent and not interoperable.由于早期ZigBee版本由于标准化做的不好，给了厂商太多选择，很多厂商虽然采用了ZigBee HA的协议，但是终端的智能家居厂商根据自家的需求定制化了ZigBee HA，而非标准ZigBee协议，导致不同厂家产品还是不能互联互通。也有点类似于Android，不同手机厂商都是采用Android系统，但是都进行了大量的定制化，导致最后的手机系统也是千差万别。

ZigBee联盟对于ZigBee HA的标准化问题也是伤透了脑筋，为此，还专门组织一批组织机构做ZigBee HA认证，比如最新的ZigBee HA1.2认证，只要经过ZigBee HA1.2认证的产品就能够实现互联互通。

智能家居不能互联互通的根本原因是应用智能家居最广泛的ZigBee协议有很多应用层协议，不同的应用层协议彼此是独立不互通的；另外即使采用相同的应用层协议，也有可能由于应用协议标准化的问题导致设备不兼容。可以说，ZigBee之前仅仅解决了智能设备的连接问题，但是没有解决智能设备的互联互通的问题。

3、ZigBee3.0 来解决智能家居互联互通了！

2016年5月，ZigBee联盟联手ZigBee联盟中国组成员在上海亚洲消费电子展（CES Asia）举办新闻发布会暨剪彩仪式，正式向亚洲市场推出了ZigBee3.0。IC厂商TI、NXP、GreenPeak、Atmel，解决方案商Wulian物联传感、顺舟智能科技，智能家居厂商飞利浦、美的等主要智能家居上下游玩家均参加了新闻发布会。

ZigBee联盟推出ZigBee3.0主要的任务就是为了统一ZigBee Home Automation （ZigBee HA）， ZigBee Light Link（ZigBee LL）， ZigBee Building Automation（ZigBee BA）， ZigBee Retail Services（ZigBee RS）， ZigBee Health Care（ZigBee HC）， ZigBee Telecommunication services（ZigBee TS）等应用层协议，解决了不同应用层协议之间的互联互通问题，用户只要购买任意一个经过ZigBee3.0的网关就可以控制不同厂家基于ZigBee3.0的智能设备。

ZigBee3.0统一了采用不同应用层协议的ZigBee设备的发现、加入和组网方式，使得ZigBee设备的组网更便捷、更统一。另外，ZigBee3.0也进一步加强了ZigBee网路的安全性。

稍显遗憾的是，ZigBee3.0并没有统一ZigBee Smart Energy 应用层协议。ZigBee应用层协议用于读取电表的电量数据，比如应用了ZigBee Smart Energy的智能家庭可以知道每个家庭每月，每个星期、甚至每天的电量数据，物业管理公司和电力公司可以实时知道每个家庭的电量消耗以便收取电费。ZigBee联盟也推出了ZigBee3.0认证来规范各个厂商使用标准的ZigBee3.0协议，以保证基于ZigBee3.0设备的互通性。

3、智能家居上下游产业链怎么看待ZigBee3.0

ZigBee3.0解决了智能家居领域应用最主流协议ZigBee不同应用层协议互联互通的问题，也进一步标准化了ZigBee协议，向智能家居的互联互通迈出了一大步，但是在和其他协议的互联互通还要继续努力。

这就需要不同的协议（或称标准）提供商继续在底层协议合作和妥协，这个合作和妥协的过程可能会比较艰难。目前最好的解决方案可能就是智能家居厂商的网关设备支持多协议标准，做统一的UI交互。

Wulian物联传感为此推出WLink万联平台，通过互利合作建立与WiFi、蓝牙等技术的连接，快速实现传统照明、门锁、家电等设备的升级，以及智能单品之间的互联互通。

WLink万联平台是一个开放性的物联网智能家居平台，以WLink超级网关为核心，支持接入ZigBee协议、WiFi协议、以太网协议等多种协议的设备，提供终端硬件、通信模块、软件应用和云服务等多个个性化解决方案。在AWE2016上，在Wulian展厅内设立的WLink万联平台展区，就将会云集包括海尔、创维、海信、TCL、九阳、美的等在内的多家知名的家电厂商。

于2017年初，海信全系列产品均已对接完成《海信智能家电介绍及使用教程》，而目前在WLink平台达成合作的企业产品有：海信全系列家电、美的中央空调、晾霸晾衣架、霍尼韦尔烟感、宁波向往背景音乐、狗尾草小白机器人、路可视门锁、费加罗燃气探测器等等，现还有更多的产品正在对接中，后续将会有更多企业及其产品达成深度合作。

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