ZigBee uses the IEEE 802.15.4 physical layer and link standard, operates in the 2.4 GHz ISM band with a range of up to 300 feet. Supports mesh topology. Consequently, the network can be extended over a greater distance using multi-hop operations. The protocol is highly interoperable and includes standard libraries for data models, security, and network management procedures. ZigBee features low power, node discovery, duplicate packet detection, route discovery, sleep mode, and reliability. It is widely used in home automation and building automation applications.

Zigbee is an IEEE 802.15.4-based specification for a suite of high-level communication protocols used to create personal area networks with small, low-power digital radios, such as for home automation, medical device data collection, and other low-power low-bandwidth needs, designed for small scale projects which need wireless connection. Hence, Zigbee is a low-power, low-data-rate, and close proximity (i.e., personal area) wireless ad hoc network.

The technology defined by the Zigbee specification is intended to be simpler and less expensive than other wireless personal area networks (WPANs), such as Bluetooth or more general wireless networking such as Wi-Fi (or Li-Fi). Applications include wireless light switches, home energy monitors, traffic management systems, and other consumer and industrial equipment that requires short-range low-rate wireless data transfer.

Its low power consumption limits transmission distances to 10–100 meters (30' to 300') line-of-sight, depending on power output and environmental characteristics. Zigbee devices can transmit data over long distances by passing data through a mesh network of intermediate devices to reach more distant ones. Zigbee is typically used in low data rate applications that require long battery life and secure networking. (Zigbee networks are secured by 128-bit symmetric encryption keys.) Zigbee has a defined rate of up to 250 kbit/s, best suited for intermittent data transmissions from a sensor or input device.

Line of sight (LoS) propagation from an antenna

Reliability

ZigBee range results

Testing of Communication Range in ZigBee Technology

testing-of-communication-range-in-zigbee-technology-1dyb1hdutf.pdf

Data Rate Wireless Standard

Types of IoT protocols

Zigbee builds on the physical layer and media access control defined in IEEE standard 802.15.4 for low-rate wireless personal area networks (WPANs). The specification includes four additional key components: network layer, application layer, Zigbee Device Objects (ZDOs) and manufacturer-defined application objects. ZDOs are responsible for some tasks, including keeping track of device roles, managing requests to join a network, as well as device discovery and security.

Zigbee operates in the industrial, scientific and medical (ISM) radio bands. With the 2.4 GHz band being primarily used for lighting and home automation devices in most jurisdictions worldwide. While devices for commercial utility metering and medical device data collection often use “Sub-GHz” frequencies, (902-928 MHz in North America, Australia, and Israel, 868-870 MHz in Europe, 779-787 MHz in China, even those regions and countries still using the 2.4 GHz for most globally sold Zigbee devices meant for home use. With data rates varying from around 20 kbit/s for Sub-1GHz bands to around 250 kbit/s for channels on the 2.4 GHz band range).

Device types

Three different types of Zigbee device are defined according to their role in the network:

• Zigbee Coordinator (Zigbee Coordinator, ZC). The most complete type of device. There should be only one per network. Its functions are to control the network and the paths that the devices must follow to connect with each other.
• Zigbee Router (Zigbee Router, ZR). It interconnects separate devices in the network topology, as well as providing an application layer for executing user code.
• End device (Zigbee End Device, ZED). It has the necessary functionality to communicate with its parent node (the coordinator or a router), but it cannot transmit information intended for other devices. In this way, this type of node can be asleep most of the time, increasing the average life of its batteries. A ZED has minimal memory requirements and is therefore significantly cheaper.

As an example of an application in Home Automation, in a room of the house we would have various End Devices (such 
as a switch and a lamp) and an interconnection network made with Zigbee Routers and governed by the Coordinator.

Types of addresses:

• Manufacturer address: 64-bit number, example: 041A45B38D928AAA.
• Address given by the coordinator: 16-bit number, example: 0x23f7.
• Text string: example: “Gas sensor node”.

The Zigbee network layer natively supports both star and tree networks, and generic mesh networking.

Network topologies:

• Star topology: the coordinator is located in the center.
• Tree topology: the coordinator will be the root of the tree.
• Mesh topology: at least one of the nodes will have more than two connections.

Every network must have one coordinator device. Within star networks, the coordinator must be the central node. Both trees and meshes allow the use of Zigbee routers to extend communication at the network level. Another defining feature of Zigbee is facilities for carrying out secure communications, protecting establishment and transport of cryptographic keys, ciphering frames, and controlling device. It builds on the basic security framework defined in IEEE 802.15.4.

Zigbee devices must adhere to the IEEE 802.15.4-2003 low-rate WPAN standard. This defines the lowest levels: the physical layer (PHY) and the medium access control (MAC, part of the data link layer, DLL). The standard works on the ISM bands for unregulated use detailed above. Up to 16 channels are defined in the 2.4 GHz range, each with a bandwidth of 5 MHz. The center frequency of each channel can be calculated as: FC = (2405 + 5*(k-11)) MHz, with k = 11, 12,…, 26.

Regarding the frequencies used, three bands with 27 channels available:

• 2.4 GHz: 16 channels and 250 kbps
• 902-928 MHz: 10 channels and 40 Kbps
• 868.3 MHz: one channel and 20 Kbps

Radios use a direct sequence spread spectrum (DSSS). BPSK is used in the two lower frequency ranges, as well as an orthogonal QPSK that transmits two bits per symbol in the 2.4 GHz band. This allows transmission rates in the air of up to 250 kbps, while the lower bands are have expanded with the latest revision to this rate from the 40 kbps of the first version. Transmission ranges range between 10 and 75 meters, although they depend quite a bit on the environment. The output power of radios is usually 0 dBm (1 mW).

As an interface, it uses the DSSS (Direct Sequence Spread Spectrum) technique with different modulations:

• BPSK for the 868 and 915 frequencies, with the channel bandwidth is 2 MHz.

• 902-928 MHz: 10 channels and 40 Kbps
• 868.3 MHz: one channel and 20 Kbps

• O-QPSK for the 2.4 GHZ ISM band, with the channel bandwidth is 5 MHz.

• 2.4 GHz: 16 channels and 250 kbps

This scheme is 2-symbol phase shift modulation. It is also known as 2-PSK or PRK (Phase Reversal Keying). It is the simplest of all, since it only uses 2 symbols, with 1 bit of information each. It is also the one with the greatest immunity to noise, since the difference between symbols is maximum (180°). Such symbols typically have a phase jump value of 0° for 1 and 180° for 0, as shown in a constellation diagram. Instead, its transmission speed is the lowest of the phase modulations.

In the presence of a phase shift, introduced by the communications channel, the BPSK demodulator is unable to determine the correct symbol. Because of this, the data stream is differentially encoded before modulation. BPSK is functionally equivalent to 2-QAM modulation.

BPSK (Binary PSK)

Quadrature phase shift keying (QPSK) is a form of phase shift keying in which two bits are modulated at a time, selecting one of four possible carrier phase shifts (0, 90, 180 or 270 degrees). QPSK allows the signal to carry twice as much information as normal PSK using the same bandwidth.

Quadrature phase-shift keying (QPSK)

Constellation diagram

Modulation Schemes

Although CSMA/CA is generally used to avoid collisions in transmission, there are some exceptions to its use: on the one hand, the frames follow a fixed timing that must be respected; On the other hand, shipping confirmations do not follow this discipline either; Finally, if guaranteed time slots are allocated for a transmission, contention is also not possible.

In Zigbee networks, two types of environments or systems can be used:

• Beacon-enabled: the data is sent periodically over the network. In between the time period when the devices are not sending data, they may enter a low power sleep state to minimize power consumption, this mode is more recommended when the network coordinator works with a battery. The devices that make up the network listen to said coordinator during “beaconing” (sending messages to all devices -broadcast-, between 0.015 and 252 seconds). A device that wants to intervene, the first thing it will have to do is register for the coordinator, and that is when it looks to see if there are messages for it. In the event that there are no messages, this device goes back to “sleep”, and wakes up according to a schedule previously established by the coordinator. As soon as the coordinator finishes the “beacon”, he goes back to “sleep”.
• Non-beacon- enabled: in this case, the network coordinator is powered by the main network at all times. In this type, each device is autonomous, being able to start a conversation, in which the others can interfere. Sometimes, it may happen that the destination device may not hear the request, or the channel may be busy. This system is typically used in security systems, in which their devices (sensors, motion detectors or glass break detectors) sleep practically all the time (99.999%). To be taken into account, these elements “wake up” regularly to announce that they are still on the network. When an event occurs (in our system it will be when something is detected), the sensor “wakes up” instantly and transmits the corresponding alarm. It is at that moment when the network coordinator receives the message sent by the sensor and activates the corresponding alarm.

Functionality

Based on its functionality, a second classification can be proposed:

• Full functionality device (FFD): Also known as an active node. It is capable of receiving messages in 802.15.4 format. Thanks to the additional memory and computing capacity, it can function as a Zigbee Coordinator or Router, or it can be used in network devices that interface with users.
• Reduced Functionality Device (RFD): Also known as a passive node. It has limited capacity and functionality (specified in the standard) with the aim of achieving low cost and great simplicity. Basically, they are the sensors/actuators of the network.

A Zigbee node (both active and passive) reduces its consumption because it can remain asleep most of the time (even many days in a row). When its use is required, the Zigbee node is capable of waking up in a very short time, only to go back to sleep when it is no longer required. Any node wakes up in approximately 15 ms. In addition to this time, other common function time measurements are shown:

• Reenumeration of slave nodes (by the coordinator): approximately 30 ms.
• Channel access between an active and a passive node: approximately 15 ms

A Zigbee module

Zigbee vs Bluetooth

Zigbee is very similar to Bluetooth but with some differences and advantages for home automation:

• A Zigbee network can have a maximum of 65,535 nodes distributed in subnets of 255 nodes, compared to the maximum eight for a Bluetooth subnet (Piconet).
• Lower power consumption than Bluetooth. In exact terms, Zigbee has a consumption of 30 mA transmitting and 3 μA at rest, compared to the 40 mA transmitting and 200 μA at rest that Bluetooth has. This lower consumption is due to the fact that the Zigbee system stays asleep most of the time, while in a Bluetooth communication this cannot occur, and it is always transmitting and/or receiving.
• It has a speed of up to 250 kbit/s, while in Bluetooth it is up to 3000 kbit/s.
• Due to the speeds of each, one is more appropriate than the other for certain things. For example, while Bluetooth is used for applications such as mobile phones and home computing, the speed of Zigbee becomes insufficient for these tasks, diverting it to uses such as Home Automation, battery-dependent products, medical sensors, and in toy items, in which the data transfer is less.
• There is a version that integrates the characteristic Bluetooth radio frequency system along with an infrared data transmission interface developed by IBM using an ADSI and MDSI protocol.

Best practices:

• Move the WiFi router or access point at least 5 meters (15 feet) away from the mesh controller.
• Limit each mesh to 70 or fewer nodes. Performance degrades when too many devices are connected.
• If you have more devices, configure another mesh controller and distribute devices between them as evenly as possible.
• Best zigbee channel for device compatibility; Konke Temp/Humidity sensors 15, 20, 25.; Philips Hue Green 4 button device 11, 15, 20, 25.
• Select a ZigBee channel that does not overlap with WiFi. ZigBee channels 15, 20, and 25 work best with the most common WiFi channels.
• Construction materials significantly attenuate or block ZigBee signals. Don't put a mesh controller near an interference source.

WI-FI 6 REFERENCE

wi-fi_ha_low

low-power_wide-area_network

iot_ecosystem

wi_fi_vs_zigbee_vs_z_wave_what_is_the_difference

This document describes the principals and configuration of the Aruba IoT integrations using ArubaOS/Aruba Instant version 8.8.0.0 or higher: Aruba IoT Configuration Guide

IoT Concepts

Aruba Networks: IoT Configuration - Zigbee Profile Configuration

IoT-Utilities

ZigBee addressing Addressing within the node

Airheads Broadcasting

Aruba Networks IoT

ARUBA IOT GATEWAY SOLUTION A whitepaper by Yannick SCHAPPLER

Using the ZigBee Southbound API: Home Assistant MQTT Configuration; BLE usage on Aruba AP’s

Setup your Aruba AP/Controller

There are a few settings you need to change on the Aruba Access Point. You can change all of them the easiest via the Webinterface (-just open the IP of your AP in a browser-) or if you prefer via ssh.

In the Instant WebUI, the IoT configuration can be found under `“Services“`. Scroll down to the `”IoT“` section.

In ArubaOS MCR WebUI, the IoT configuration can be found under `”Configuration“`→`”IoT“`.

1. First you need to set a `IoT-Radio-Profile`. This radio needs to use `ZigBee` as Radio mode and needs to act as “Coordinator”. The channel can be set manually (e.g. 11) or in auto mode. If you want to use another channel, that works as well but it has to be set on all instances and supported by the devices. Philips Hue bulbs are said to support channels 11,15,20 and 25.

2. You also have to set up a `ZigBee Service profile`. Please enable “Security”, set “PAN ID” on automatic and always allow new devices to join. Users don't have to always allow new devices to join but this helps avoid connection problems when trying out the SouthBound API.

3. The `ZigBee-Socket-Device-Profile` configures which Endpoints, Clusters and Profiles are allowed. It can be configured as follows:

 Source Endpoint  Destination Endpoint  Cluster ID  Profile ID  Direction
 ---------------  --------------------  ----------  ----------  ---------
 232              11                    0006        0104        outbound

hpe_a00113045en_us_8.8_aruba_iot_interface_guide_websocket.pdf

hpe_a00119577en_us_8.9_aruba_iot_websocket_interface.pdf

Using the ZigBee Southbound API

aruba-instant-8.10-iot-websocket-interface-guide.pdf