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DBx support for ZigBee PRO

E-SPIN Wireless Network Security Assessment Services Overview

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. 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 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 250 kbit/s, best suited for intermittent data transmissions from a sensor or input device.

Zigbee was conceived in 1998, standardized in 2003, and revised in 2006. The name refers to the waggle dance of honey bees after their return to the beehive.

Zigbee PRO

Zigbee PRO, also known as Zigbee 2007, was finalized in 2007. A Zigbee PRO device may join and operate on a legacy Zigbee network and vice versa. Due to differences in routing options, Zigbee PRO devices must become non-routing Zigbee end devices (ZEDs) on a legacy Zigbee network, and legacy Zigbee devices must become ZEDs on a Zigbee PRO network. It operates on not only the 2.4 GHz band, but also the sub-GHz band.

Metageek Wi-Spy DBx and Zigbee PRO support

As long as ZigBee operates or makes noise in the 2.4 or 5 GHz frequency bands, Metageek Chanalyzer + Wi-Spy hardware and software will see it. Keep in mind that Metageek specialize in WiFi (802.11) traffic, so Metageek can’t parse or analyze ZigBee packets (802.15.4) like Metageek do WiFi packets but Metageek can still see it show up in the spectrum. Additionally, you can overlay the ZigBee channels under the View menu to better identify ZigBee operations.

Metageek recommend following further reading:

ZigBee and WiFi Coexistence

ZigBee and WiFi channels both exist in the 2.4 GHz band, existing in the exact same frequency space. When deploying both WiFi and ZigBee in the same environments, careful planning must be performed to make sure that they don’t interfere with each other.

Operating a ZigBee network and a WiFi network on the same frequency will cause them to interfere with each other. Usually, the ZigBee network will take the hit.

ZigBee and WiFi Channels

ZigBee and WiFi channel numbers may seem similar, suggesting that they won’t overlap. Unfortunately, this is not the case.

2.4 GHz WiFi Channels

WiFi’s three non-overlapping channels (1, 6, and 11) use the exact same frequencies as ZigBee channels 11-22.

ZigBee channels 25-26 aren’t immune either, because they can be caught in WiFi channel 11’s sideband lobe (see Sideband Lobes below). ZigBee channel 26 is usually relatively unaffected by WiFi, but many ZigBee devices do not support it.

Interference

When a WiFi network is on the same channel as a ZigBee network, the WiFi network will usually interfere with the ZigBee network.

Sideband Interference

An 802.11g/n signature in the spectrum has two components:

  1. The 20 MHz “square” section that contains the data subcarriers
  2. Sideband lobes on each side, which are a normal side effect

Sideband lobes might not carry WiFi data, but they are fully capable of drowning out ZigBee transmissions.

Sideband lobes are usually only visible when you are very close to to the device that is actively transmitting (try doing a speed test or streaming an HD video). This is especially evident when your ZigBee access point and WiFi access point are in very close proximity with each other (like in the same comm closet).

Channel Planning

When deploying ZigBee and WiFi networks in the same environment, channel planning for peaceful coexistence is key.

Normally, we get three WiFi channels to work with (utilizing 1, 6, and 11), but to make room for ZigBee, we may have give up channel 11.

When we deploy our AP’s around the house, we’ll want to keep the same-channel access points as far away from each other as possible to avoid co-channel interference. This essentially creates a two-channel reuse plan, which isn’t as efficient as a three-channel reuse plan, but it will work to make space for the ZigBee gear.

A two-channel reuse plan

 

This concept can be applied to just about any variation of two channels out of 1, 6, and 11. You could place WiFi gear on channel 1 and 11, or 6 and 11, or any variant, as long as you’re making room for the ZigBee gear and placing it on a good channel.

Dealing with Neighbors

Most deployments have neighbors, and they typically run their own wireless networks, which have unpredictable channels.

When you deploy your wireless network, use Chanalyzer + Wi-Spy to:

  1. Identify what channels the neighbors are using
  2. Choose the best channels for your WiFi network
  3. Perform throughput testing on your WiFi network to determine what ZigBee channels they will interfere with
  4. Deploy ZigBee networks on channels that don’t receive interference from your WiFi, or the neighbors WiFi˜

ZigBee and WiFi Channel Chart

Below is a reference chart for ZigBee and WiFi Channels.

WiFi and ZigBee Optimization (Video)

In this video, Metageek talk about optimizing ZigBee and WiFi networks with Wi-Spy + Chanalyzer in a home automation environment. This video also makes a great crash-course for using Wi-Spy + Chanalyzer.