Zigbee

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

Testing of Communication Range in ZigBee Technology

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.

• Manufacturer address: 64-bit number, example: 041A45B38D928AAA.
• Address given by the coordinator: 16-bit number, example: 0x23f7.
• Text string: example: “Gas sensor node”.
• PAN Addresses: Zigbee networks are called personal area networks or PANs. A unique PAN identifier (PAN ID) defines each network and the identifier is common among all devices of the same network. Zigbee devices are either preconfigured with a PAN ID to join, or they can discover nearby networks and select a PAN ID to join. The value of the personal area network can be set through the PAN ID (ID) parameter. If this value is 0, the XBee automatically selects the PAN ID, so you can read it using the Operating PAN ID (OP) parameter; 16 bit (65,536 Possible directions).

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

• 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.

Zigbee is a low-power, low data rate wireless connectivity technology that is used to create short range wireless personal area networks (WPAN). It is a wireless communication protocol that is intended to simplify the network architecture and make it less expensive compared to other WLAN technologies like Bluetooth and Wi-Fi.

Zigbee is based on the IEEE 802.15.4 specification or standard set by the Institute of Electrical and Electronics Engineers (IEEE) that defines the amount of transmit power to be sent out from Zigbee radios, frequency range, bandwidth, data rate and other parameters. This standard defines operation of Zigbee radios in the unlicensed Industrial, Scientific, and Medical (ISM) bands that are from 2.4 to 2.4835 GHz, 902 to 928 MHz, and 868 to 868.6 MHz.

The table given below shows various frequency bands used by Zigbee along with the corresponding data rates, modulation techniques, and others.

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

An SDR implementation of WiFi receiver for mitigating multiple co-channel ZigBee interferers

Like Wi-Fi, Zigbee technology also uses a number of channels in these frequency bands to transmit and receive data from Zigbee-enabled devices in applications such as home automation, medical device data collection, wireless light switches, energy and traffic monitoring, and other consumer electronic devices that requires relatively low-power and data rate. The channels Zigbee uses are divided across different countries with each country using different set of channels for various purposes. In general, the common frequency band of Zigbee is 2.4 GHz.

Across these channels, every Zigbee device utilizes a bandwidth of up to 2 MHz while any two different channels are separated by a guard band of 5 MHz to prevent interference due to other Zigbee devices. The data rate that can be achieved in the 2.4 GHz band is 250 Kbps per channel, 40 Kbps per channel in the 915 MHz band, and 20 Kbps per channel in the 868 MHz band. However, the actual throughput that can be delivered is inevitably less than the specified values, owing to various factors such as packet overhead, processing delays, and channel latency. Zigbee radios generally deliver an output power of 1-100 mW across these frequency bands.

Note: Wi-Fi and Zigbee utilize the 2.4 GHz band, it is possible that Zigbee radios may face interference due to 
Wi-Fi devices, thereby degrading the signal quality of Zigbee network. However, channel numbers 1, 6, or 11 are 
generally occupied by Wi-Fi networks which imply that many Zigbee channels are interference-free. Specifically, 
channels 15, 20, 25 and 26 of Zigbee are always free and do not interfere due to Wi-Fi regardless of which Wi-Fi 
channel is utilized at any time. Therefore, when Zigbee radios face interference issues, they can be switched to 
these channels in order to maintain a stable network performance, data rate, and minimize latency. The Figure 
shown below illustrates the various frequency bands used by both Zigbee and Wi-Fi.

Summary:  Zigbee 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).

Note: Bluetooth 5.0 Low Energy (BLE) Radios use a Gaussian frequency shift Keying: BT classic uses FHSS, or 
Frequency Hopping Spread Spectrum. BLE uses a version of Direct Sequence Spread Spectrum which is a bit more 
deterministic. Both use a modulation scheme referred to as Gaussian frequency shift Keying, or GFSK.

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.

• 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.

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 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.

• 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

AeroScout® Location Engine Integration with Aruba Wireless Infrastructure

Aruba Asset Tracking

Example configuration: Aruba, a Hewlett Packard Enterprise (HPE) company supports IoT applications based on Wi-Fi (e.g. Wi-Fi tracking), BLE (e.g. asset tracking and sensor monitoring), ZigBee and 3rd party protocols via USB-extension by providing the connection layer using Aruba access points as protocol translation gateways.

IoT-Utilities

ZigBee addressing

Addressing within the node

Airheads Broadcasting

Aruba Networks IoT

ARUBA IOT GATEWAY SOLUTION A whitepaper by Yannick SCHAPPLER

IoT Operations

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

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
11               232                   0006        0104        inbound
232              11                    0300        0104        outbound
232              11                    0008        0104        outbound

4. Last but not least you have to enable the Zigbee Data Transport Service in the IoT Transport Profile. If you used the demo server described in this repository use port 7443 as follows: “ws://<yourIP>:7443/test” . In this Transport Profile you have to select the Socket Device you created above.

Continue with the following link:

Using the ZigBee Southbound API

Aruba Meridian login

Aruba Meridian SP

Aruba Meridian EN

Note: Aruba Beacons: These low-power wireless transmitters broadcast radio signals at regular intervals that can 
be heard by iOS and Android devices equipped with Meridian-powered mobile apps from Aruba and our Meridian app 
development partners. With Aruba Beacons, enterprises can communicate directly with the mobile device to identify 
location or for wayfinding.

Other RTLS solutions:

zebra RTLS

Aruba Beacons

Note: Aruba Asset tags are identification tags attached to assets. These small, durable labels contain unique 
identifiers that allow businesses to track and monitor their physical assets, from computers and equipment to 
furniture and vehicles;  BLE-based Aruba Tags and location-ready Aruba access points ensure you can find things 
fast, indoors and outdoors. Leverage your existing infrastructure to trilaterate the tags’ signal and understand 
the location of the tags. 

HPE Aruba Networking tags

Note: Aruba and ZF Openmatics: Aruba and ZF Openmatics offer a solution for managing ZF TAGs and implementing BLE Bluetooth Low Energy functionality. This integration enables devices to run for extended durations with low power consumption; You can manage ZF TAGs and implement BLE location service using the third-party ZF Openmatics. To support this feature, Aruba Instant APs with built-in IoT-protocol radio (BLE) are required. You can configure the Instant APs to support ZF Openmatics using the IoT profiles.

ZF Openmatics Support for ZF BLE Tag Communication

Aruba and ZF Openmatics

HPE 8.8 Aruba IoT interface guide Websocket

HPE 8.9 Aruba IoT interface guide Websocket

Using the ZigBee Southbound API

HPE 8.10 Aruba IoT interface guide Websocket

Aruba Networks and WSS WSS (Web Security Service) is a cloud-based security service that can be integrated with Aruba Branch Gateways to provide secure connections and protect against threats.

Aruba access points can be used as transmitters/receivers or just receivers/sensors for various purposes, including BLE connect, ZigBee, BLE asset tracking, and Wi-Fi tracking. WSS can be configured to manage and secure these connections.

Note:  Aruba Central, a cloud-based network management platform, uses WSS for secure communication with streaming 
servers. You can configure the communication protocol and token protocol for WSS within Aruba Central.

Configuring Web Security Service for SD-Branch Integration

Aruba, a Hewlett Packard Enterprise (HPE) company (https://www.arubanetworks.com/) supports IoT applications based on Wi-Fi (e.g. Wi-Fi tracking), BLE (e.g. asset tracking and sensor monitoring), ZigBee and 3rd party protocols via USB-extension by providing the connection layer using Aruba access points as gateways.

Download Aruba IoT-Utilities for Android.

IoT-Utilities user guide.