Zigbee is an IEEE 802.15.4-based specification for high-level communication protocol packets used to create private area networks with small, low-power digital radios such as home automation, medical data collection devices, and low-power requirements other low-bandwidth, designed for small-scale projects that require wireless connections. Therefore, Zigbee is a low-level, low-power, and near-wireless data (ie, private area) wireless ad hoc network.
The technology specified by the Zigbee specification is intended to be simpler and less expensive than other wireless private area networks (WPANs), such as Bluetooth or common wireless networks such as Wi-Fi. Applications include wireless light switches, home energy monitors, traffic management systems, and other consumer and industrial equipment that require low-speed wireless data transfers over short distances.
Low power consumption limits the transmission distance to 10-100 meters line-of-sight, depending on power output and environmental characteristics. Zigbee devices can transmit data remotely by sending data over the mesh network of intermediate devices to reach further away. Zigbee is typically used in low data rate applications requiring long battery life and secure networks (Zigbee networks secured by 128-bit symmetric encryption keys.) Zigbee has a set rate of 250 kbit/s, best suited for intermittent data transmission of a sensors. or input device.
Zigbee was conceived in 1998, standardized in 2003, and revised in 2006. Its name refers to the waggle dance of honeybees after they return to the honeycomb.
Video Zigbee
Ikhtisar
Zigbee is a low-cost, low-powered wireless mesh network standard intended for battery-powered devices in wireless control and monitoring applications. Zigbee provides low latency communications. Zigbee chips are usually integrated with radio and with microcontroller. Zigbee operates in the industrial, scientific and medical radio band (ISM): 2.4 GHz in most jurisdictions around the world; although some devices also use 784 MHz in China, 868 MHz in Europe and 915 MHz in the United States and Australia, but even those regions and countries still use 2.4 GHz for most commercial Zigbee devices for home use. Data rates vary from 20 kbit/s (band 868 MHz) to 250 kbit/second (2.4 GHz band).
Zigbee is built on the physical layer and media access control specified in the IEEE 802.15.4 standard for low speed wireless private area networks (WPAN). The specification includes four additional key components: network layer, application layer, Zigbee Device Objects (ZDOs) and application objects specified by the manufacturer. ZDO is responsible for several tasks, including tracking device roles, managing requests to join the network, and discovering and security of devices.
The Zigbee network layer natively supports star and tree networks, and generic mesh networks. Each network must have one coordinator device. In a star network, the coordinator must be a central node. Both trees and meshes allow the use of Zigbee routers to extend communication at the network level. Another decisive feature of Zigbee is the facility for secure communication, protecting the formation and transport of cryptographic keys, random frames, and control devices. It is built on a basic security framework defined in IEEE 802.15.4.
Maps Zigbee
History
Zigbee's ad-hoc digital radio network was conceived in the 1990s. The IEEE 802.15.4-2003 Specs Zigbee was ratified on December 14, 2004. Zigbee Alliance announced the availability of Specification 1.0 on June 13, 2005, known as the Zigbee 2004 Specification .
Cluster library
In September 2006, Zigbee 2006 Specification was announced, removing the 2004 Standard 2006 stack replacing the Key/Values ​​Important structure used in the 2004 stack with the cluster library . Libraries are a set of standard commands, organized in groups known as clusters with names like Intelligent Energy , Home Automation , Zigbee Light Link .
In January 2017, the Zigbee Alliance renamed the library to Dotdot and announced it as a new protocol to be represented by an emoticon ||: They also announced that it would now run more than that other. the network type uses the Internet Protocol and will interconnect with other standards such as Thread.
Zigbee PRO
Zigbee PRO, also known as Zigbee 2007, enhanced the Zigbee Pro Specification, was completed in 2007. The Zigbee PRO device can join and operate on old Zigbee networks and vice versa. Due to different routing options, Zigbee PRO devices must be non-routing Zigbee End-Devices (ZEDs) on old Zigbee networks, and Zigbee inheritance devices must be ZED on the PRO Zigbee network.
Apps running on the device work together, regardless of the underlying stack profile. The first Zigbee Application Profile, Home Automation, was announced 2nd November 2007.
Use the letters
The Zigbee protocol is intended for embedded applications that require low power consumption and tolerate low data rates . Zigbee is not for situations with high mobility between nodes. Therefore, it is not suitable for tactical ad hoc radio networks in the battlefield, where high data rate and high mobility are present and required. The resulting network will use a very small amount of power - the individual device must have at least two years of battery life to pass Zigbee certification.
Common application areas include:
- Entertainment and Home Control - Home automation such as QIVICON, smart lighting, advanced temperature control, safety and security, movies and music
- Wireless sensor network - Starts with individual sensors such as Telosb/Tmote and Iris from Memsic
- Industrial controls
- Embedded sensing
- Medical data collection
- Warning of smoke and intruders
- Building automation
- Remote wireless microphone configuration, in the Shure Wireless Microphone System
Standard and profile
Established in 2002, Zigbee Alliance is a group of companies that maintain and publish Zigbee standards. The term Zigbee is a registered trademark of this group, not a technical one. The Alliance publishes an application profile that allows multiple OEM vendors to create interoperable products. The relationship between IEEE 802.15.4 and Zigbee is similar to that between the IEEE 802.11 and the Wi-Fi Alliance.
Zigbee Alliance Membership
The Zigbee Alliance has three membership levels: Adopter, Participant, and Promoter. Adopter members are allowed to access completed Zigbee specifications and standards, and Participant members have voting rights, play a role in Zigbee development, and have early access to specifications and standards for product development.
Requirements for membership in the Zigbee alliance cause problems for developers of Free Software because annual fees conflict with the GNU General Public License. The requirements for developers to join the Zigbee Alliance also conflict with most other free software licenses.
The Zigbee Alliance Board has been required to make their licenses compatible with the GPL, but it was rejected. Bluetooth has a GPL licensed implementation.
App profile
The list of currently app applications published, or under development is:
Released specifications
- House Automation 1.2
- Smart Energy 1.1b
- Smart Energy 1.2
- Energy Smart 1.2a
- Smart Energy 1.2b
- Telecommunication Services 1.0
- Health Care 1.0
- RF4CE - Remote Control 1.0
- RF4CE - Input Device 1.0
- Long Distance Control 2.0
- Link 1.0 Light
- IP 1.0
- Commercial Building Automation 1.0
- Gateway 1.0
- Green Power 1.0 (Remote control feature without optional battery from Zigbee 2012)
- Retail Services
Specifications are being developed
- Zigbee Smart Energy 2.0
- Smart Energy 1.3 (not released)
- Smart Energy 1.4
- Light Link 1.1
- House Automation 1.3
The Zigbee Smart Energy V2.0 specification defines Internet protocols for monitoring, controlling, informing and automating energy and water delivery and use. This is an enhanced Zigbee Smart Energy version 1 specification. It adds services for charging, installation, configuration and firmware plug-in electric vehicles, prepaid services, user and messaging information, load control, demand responses and general information and application profile interface for the network wired and wireless. These are being developed by partners including:
- The HomeGrid Forum is responsible for marketing and certifying ITU-T G.hn technologies and products
- HomePlug Powerline Alliance
- SAE International International Automotive Engineers
- IPSO Alliance
- SunSpec Alliance
- Wi-Fi Alliance.
Zigbee Smart Energy relies on Zigbee IP, the network layer that drives standard IPv6 traffic to IEEE 802.15.4 using 6LoWPAN header compression.
In 2009, RF4CE (Radio Frequency for Consumer Electronics) Consortium and Zigbee Alliance agreed to provide together a standard for radio frequency remote control. Zigbee RF4CE is designed for a variety of consumer electronics products, such as TVs and decoders. It promises many advantages over existing remote control solutions, including richer communication and improved reliability, improved features and flexibility, interoperability, and no line barrier. The Zigbee RF4CE specification lifts the network load and does not support all mesh features, which are traded for smaller memory configurations for lower cost devices, such as consumer electronic remote controls.
With the introduction of the second Zigbee RF4CE application profile in 2012 and the increasing momentum in the MSO market, the Zigbee RF4CE team provides an overview of the current status of standards, applications, and the future of technology.
Radio hardware
The radio design used by Zigbee has several analog stages and uses digital circuits wherever possible.
Although the radio itself is not expensive, the Zigbee Qualification Process involves full validation of the physical layer requirements. All radios coming from similarly validated semiconductor mask sets will enjoy the same RF characteristics. Physical layers that are not certified malfunctions can disable the battery life of other devices on the Zigbee network. Radio Zigbee has a very tight constraint on power and bandwidth. Thus, the radio is tested with guidance given by Clause 6 of Standards 802.15.4-2006. Products that integrate radio and microcontroller into one module are available.
This standard specifies operations in 2.4 unilensed to 2,4835 GHz (worldwide), 902 to 928 MHz (America and Australia) and 868 to 868.6 MHz (Europe) ISM groups. Sixteen channels are allocated in the 2.4 GHz band, with each channel spaced 5 MHz apart, though only using 2 MHz bandwidth. Radio uses direct-spreading sequence spectrum encoding, which is managed by the digital stream to the modulator. Binary phase-shift keying (BPSK) is used on bands 868 and 915 MHz, and offset quadrature phase-shift keying (OQPSK) that transmits two bits per symbol used in the 2.4 GHz band.
The raw data, over-the-air data rate is 250 kbit/s per channel in 2.4 GHz bands, 40 kbit/s per channel on the 915 MHz band, and 20 kbit/d in 868 MHz bands. Actual data throughput will be less than the specified maximum bit rate due to packet overhead and processing delays. For indoor applications with a transmission distance of 2.4 GHz may be 10-20 m, depending on construction materials, the number of walls to be penetrated and the permitted output power in those geographical locations. Outdoors with line-of-sight, range may be up to 1500 m depending on power output and environmental characteristics. The output power of the radio is generally 0-20 dBm (1-100 mW).
Device type and operation mode
Zigbee devices consist of three types:
- Zigbee Coordinator (ZC) : The most capable device, Coordinator forms the root of the network tree and possibly bridges to other networks. There is one Zigbee Coordinator on each network because it is the device that started its initial network (the Zigbee LightLink specification also enables operations without the Zigbee Coordinator, making it more usable for off-the-shelf home products). It stores information about the network, including acting as a Trust & amp; repository for security keys.
- Zigbee Router (ZR) : As well as running application functions, Routers can act as intermediate routers, forwarding data from other devices.
- Zigbee End Device (ZED) : Contains sufficient functionality to talk to the parent node (either the Coordinator or the Router); it can not send data from other devices. This relationship allows the node to fall asleep in a significant amount of time so as to provide a long battery life. ZED requires the least amount of memory, and, therefore, can be cheaper to produce than ZR or ZC.
The Zigbee protocol currently supports beacon and non-beacon networks enabled. In a network that is not enabled by the beacon, a non-spotted CSMA/CA channel access mechanism is used. In this type of network, the Zigbee Router usually has a continuously active receiver, requiring a stronger power supply. However, this allows for heterogeneous networks where multiple devices receive continuously while others only transmit when external stimuli are detected. A typical example of a heterogeneous network is a wireless light switch: The Zigbee Node on the lamp may continue to receive, as it is connected to the mains supply, while the battery-powered switch will stay asleep until the switch is thrown. The switch then wakes up, sends commands to lights, receives recognition, and goes back to sleep mode. In a network, the lamp node will at least be a Zigbee Router, if not the Zigbee Coordinator; The switch node is usually the Zigbee End Device.
In a beacon-enabled network, a special network node called Zigbee Routers sends a periodic beacon to confirm their presence to other network nodes. Nodes can sleep between beacons, thus lowering their duty cycle and extending the life of their batteries. Interval beacons depend on the data rate; they can range from 15.36 milliseconds to 251.65824 seconds at 250 kbit/s, from 24 milliseconds to 393.216 seconds at 40 kbit/s and from 48 milliseconds to 786.432 seconds at 20 kbit/s. However, low cycle operations with long flare intervals require precise timing, which may conflict with low product cost requirements.
In general, the Zigbee protocol minimizes the timing of the radio on, thereby reducing power usage. In a beaconing network, the node only needs to be active when the beacon is being sent. In networks that are not enabled by flare, power consumption is clearly not symmetrical: Some devices are always active while others spend most of their time sleeping.
Except for the Smart Energy 2.0 Profile, Zigbee devices must comply with the standard IEEE 802.15.4-2003 Standard Wireless Network (LR-WPAN) standard. Standard sets lower layer protocols - physical layer (PHY), and Media Access Control section in the data link layer (DLL). Basic channel access mode is "operator sense, double access/collision avoidance" (CSMA/CA). That is, the knot speaks in the same way as humans communicate; they briefly checked to see that no one spoke before he started, with three important exceptions. Beacons are sent on a fixed time schedule and do not use CSMA. A thank-you message also does not use CSMA. Finally, devices in networks that support beacons that have real-time low latency requirements can also use Guaranteed Time Slots (GTS), which by definition do not use CSMA.
Software
The software is designed to be easy to develop on small, inexpensive microprocessors. For more details, please use one or more of the sources listed in the References section below, or directly to the Zigbee Alliance website using the External link provided below.
Network layer
The main function of the network layer is to allow the correct use of the MAC sublayer and provide the appropriate interface for use by the next up layer, ie the application layer. Its capabilities and structure are typically associated with the network layer, including routing. The Network Layer function just as it sounds. It deals with network functions such as connecting, disconnecting, and managing the network. This will add networks, allocate addresses, and add/remove specific devices. This layer utilizes star topology, mesh, and tree. This adds an interface to the application layer.
On the one hand, data entities create and manage network data layer units from the application layer payload and perform routing according to the current topology. On the other hand, there is a layer of control , which is used to handle new device configurations and build new networks: it can determine whether the neighbor's devices belong to the network and find new neighbors and routers. The controls can also detect the presence of the receiver, which allows direct communication and MAC synchronization.
The routing protocol used by the network layer is AODV, which has properties similar to Associativity-based Routing (ABR). Unlike AODV, ABR is a patented routing protocol invented in 1994 at Cambridge University, England. AODV is a working IETF draft, which consistently adds features from various suggestions and sources over time. At AODV, to find the destination device, AODV broadcasts a route request to all its neighbors. The neighbors then broadcast the request to their neighbors and so on until the goal is reached. Once the goal is reached, it sends a route reply via unicast transmission following the lowest cost path back to the source. The route discovery approach is exactly the same with those of Routativity-based Routing, except that ABR does not use sequence numbers or distance vectors. Once the source receives a reply, it will update its route table for the next destination jump destination in the path and track cost.
Application layer
The application layer is the highest level layer defined by the specification and is the effective interface of the Zigbee system for the end user. It consists of most components added by the Zigbee specification: both ZDO and its management procedures, along with the application object specified by the manufacturer, are considered part of this layer. This layer binds tables, sends messages between devices that are bound, manages group addresses, reassembles packets and also transports data. It is responsible for providing services for Zigbee device profiles.
Main components
The ZDB (Zigbee Device Object), the protocol in the Zigbee protocol stack, is responsible for overall device management, security keys, and policies. Responsible for defining the role of the device either as coordinator or end device, as mentioned above, but also for the invention of new devices (one-hop) on the network and identification of services offered. You can then continue to build secure links with external devices and reply to binding requests.
The application support sublayer (APS) is another major standard component of the layer, and therefore offers a well-defined interface and control service. It serves as a bridge between the network layer and other elements of the application layer: it creates the latest binding table in the form of a database, which can be used to find the appropriate device depending on the services required and offered by different devices. As a union between two particular layers, it also directs messages across the layers of the protocol stack.
Model communication
Applications may consist of communicating objects that work together to perform the desired task. Zigbee's focus is to distribute the work among many different devices that reside within individual Zigbee nodes which in turn form a network (verbs will usually be mostly local to each device, for example, control of every household appliance).
The collection of objects that make up the network communicate using the facilities provided by APS, overseen by the ZDO interface. The application layer data service follows a typical request-confirmation/indication-response structure. In one device, up to 240 application objects can exist, numbered in the 1-240 range. 0 is reserved for ZDO and 255 data interfaces for broadcast; the 241-254 range is currently not in use but may be in the future.
Two services are available for the application object to use (in Zigbee 1.0):
- The key-value pairing service (KVP) is intended for configuration purposes. It allows the description, request and modification of object attributes via a simple interface based on get/set and primitive events, some allowing requests for responses. Configuration using compressed XML (complete XML can be used) to provide an easily customized and elegant solution.
- The messaging service is designed to offer a general approach to information maintenance, avoiding the need to adapt application protocols and potential overheads issued by KVP. This allows the arbitrary payload to be transmitted via APS frames.
Overcoming is also part of the application layer. A network node consists of an 802,15,4-conform radio transceiver and one or more device descriptions (basically collection of attributes that can be surveyed or arranged, or that can be monitored through events). The transceiver is the base for addressing, and the device in the node is determined by the endpoint identifier in the 1-240 range.
Communication and device discovery
For apps to communicate, their composed devices must use the common application protocol (message type, format, and so on); this set of conventions is grouped into profiles . Furthermore, the binding is decided by matching the input and output cluster identifiers, unique in the context of the given profile and related to the incoming or outgoing data stream in a device. The fastener table contains both source and destination pairs.
Depending on the information available, the discovery of the device may follow different methods. When the network address is known, the IEEE address can be requested using unicast communication. When not, the petition is broadcast (the IEEE address becomes part of the response charge). The end device will only respond with the requested address while the network coordinator or router will also send the address of all the devices associated with it.
This extended discovery protocol enables external devices to find out about the devices on the network and the services they offer, which endpoints can report when asked by discovery devices (which have previously obtained their address). Suitable services can also be used.
The use of a cluster identifier enforces the binding of a complementary entity using a binding table, managed by the Zigbee coordinator, since the table must always be available in the network and the coordinator is likely to have a permanent power supply. Backups, managed by higher level layers, may be required by some applications. Binding requires established communication links; after it exists, whether to add a new node to the network is disconnected, according to the application and security policy.
Communication can take place right after the association. Direct address uses both radio address and endpoint identifier, while indirect addressing uses every relevant field (address, endpoint, cluster, and attribute) and requires it to be sent to the network coordinator, which manages the association and translate demand for communication. Indirect addressing is very useful for keeping some devices very simple and minimizing their need for storage. In addition to these two methods, broadcast to all end points in the device is available, and group addressing is used to communicate with the group's endpoints.
Security service
As one of the decisive features, Zigbee provides facilities for secure communications, protecting the formation and transport of cryptographic keys, random frames, and control devices. It is built on a basic security framework defined in IEEE 802.15.4. Part of this architecture depends on correct symmetric key management and correct application of security methods and policies.
Basic security model
The basic mechanism for ensuring confidentiality is adequate protection for all keying materials. Trust must be assumed in the initial lock installation, as well as in the processing of security information. For implementation for global jobs, conformity generally with the prescribed behavior is assumed.
Key is the cornerstone of security architecture; therefore their protection is very important, and the keys should never be transported through unsafe channels. The momentary exclusion for this rule occurs during the initial phase of addition to a previously unconfigured network of devices. Zigbee network models should be careful of security considerations, since ad hoc networks can be physically accessible by external devices. Also the working environment is unpredictable.
In the protocol stack, different network layers are not separated cryptographically, so an access policy is required, and conventional design is assumed. The open belief model within the tool allows for key sharing, which primarily reduces potential costs. However, the layer that creates the frame is responsible for its security. If a malicious device may exist, every network layer payload must be cached, so unauthorized traffic can be disconnected. An exception, again, is the network key transmission, which confers an integrated security layer to the grid, to a new connecting device.
Security Architecture
Zigbee uses a 128-bit key to implement its security mechanism. Keys can be linked both to the network, which can be used either by the Zigbee layer and the MAC sublayer, or into links, obtained through pre-installation, agreement, or transportation. Link lock creation is based on the primary key that controls key link correspondence. Ultimately, at least, the initial master key must be obtained through secure media (transport or pre-installation), because the security of the entire network depends on it. Links and primary keys are only visible to the app layer. Different services use different one-way street variations to avoid leaks and security risks.
Key distribution is one of the most important security functions of a network. Secure networks will designate a specific device that other devices trust for the distribution of security keys: a trust center. Ideally, the device will have a trust address center and initial master key loaded; if a momentary vulnerability is allowed, it will be sent as described above. General applications without special security needs will use the network key provided by the trust center (through initially insecure channels) to communicate.
Thus, the trust center maintains both the network key and provides point-to-point security. The device will only receive communications from the key provided by the trust center, except for the original master key. The security architecture is distributed among the network layers as follows:
- The MAC sublayer is capable of reliable one-hop communication. As a rule, the level of security to be used is determined by the top layer.
- The network layer governs routing, processes received messages, and is able to broadcast requests. Outbound frames will use sufficient link locks according to routing where available; otherwise, the network key will be used to protect the payload from external devices.
- The application layer offers key establishment and transport services to ZDO and applications.
The security-level infrastructure is based on CCM *, which adds encryption and integrity features only to CCM.
According to the German computer magazine website, Zigbee Home Automation 1.2 uses a fallback key for known and unchangeable encryption negotiations. This makes encryption extremely vulnerable.
Simulation
Network simulators, such as NS2, OMNeT, OPNET, and NetSim can be used to simulate the Zigbee IEEE 802.15.4 network.
This simulator comes with an open source C or C library for users to modify. In this way the user can determine the validity of the new algorithm before the hardware implementation.
See also
- Wireless ad hoc network
- Mobile ad hoc networks
- Bluetooth mesh network
- HaLow
- DASH7
- Z-WaveÃ, - RF mesh technology
- Thread (network protocol)
- 6LoWPAN
- INSTEONÃ, - dual-mesh (RF and Powerline) technology
- EnOcean
- LoRaWAN
- Comparison of 802.15.4 radio modules
- Comparison of wireless data standards
References
External links
- Official website
- Intelligent Energy Document (V2.0)
- Alliance Documents
- "ZigBee RF4CE: The Quiet Revolution is On" (PDF) . December 2012. Archived from the original (PDF) in 2013-01-18.
- What does ZigBee Pro mean for your app? by Jack Shandle, November 27, 2007
- ZigBee PRO Set Features: More of a good thing by Bob Gohn, December 18, 2007
- ZBOSS ZigBee Open Source Stack, (Certified by Zigbee Alliance)
- Zigbee for M2M Technology Find out how Zigbee can be used for M2M communications
- FreakZ open source Zigbee project, Project homepage, and Zigbee/802.15.4 chip comparison
- ZigBee wants to be Bluetooth internet. Too bad everyone hates it.
Source of the article : Wikipedia
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