CC2652P: Clarification about channels used by ZigBee Network

Roberto Nucera

Part Number: CC2652P
Other Parts Discussed in Thread: Z-STACK

Good morning

I would ask for a clarification on the channel related behaviour of the devices in a ZigBee Network.

I carefully read the Channel section of the docs, but i'm not getting a single concept: i know that the primary and secondary mask are used by network formation devices to scan for the best crowded channel in order to create their network there, while other devices use those masks to search for a network to join in the given channels.

It is not clear for me how the Z-Stack reacts if the selected channel becomes crowded or noisy later, is some sort of channel hopping machanism implemented as WiFi does?

Thank you in advance for the amazing support.

Have a nice day

Roberto

over 2 years ago

0 YiKai Chen over 2 years ago

Guru 735685 points

Actually, channel scan only happens when coordinator forms network first time. If the channel is too noisy in scan result, coordinator will use other channels which are assigned in primary and secondary channel mask.

0 Roberto Nucera over 2 years ago in reply to YiKai Chen

Intellectual 265 points

Hello YiKai, thank you.

Ok, but how the Z-Stack behaves if the channel becomes too noisy later, when the network formation is completed on that specific channel.

For example, the network formation process completes creating a network on channel 13, some hours later, that channel becomes very noisy due to other sources.

How does the Stack reacts to it? Can it switch to another channel autonomously?

+1 YiKai Chen over 2 years ago in reply to Roberto Nucera

Guru 735685 points

This is about Zigbee frequency agility. If the channel is detected too noisy, coordinator should start scan and decide new channel to use and notify devices in the network.

0 Roberto Nucera over 2 years ago in reply to YiKai Chen

Intellectual 265 points

Thank you, this was the information i was looking for.

Another thing, i see that frequency agility is an optional feature to be enabled.

Is it default active in projects like znp, zr_genericapp and zed_genericapp of the SDK?

+1 YiKai Chen over 2 years ago in reply to Roberto Nucera

Guru 735685 points

Frequency agility should be enable by default on router device. You can check ZIGBEE_FREQ_AGILITY in source code. For ZED, you don't need to enable ZIGBEE_FREQ_AGILITY since it will scan channels to rejoin when it loses connection with parent node.

+1 Ryan Brown1 over 2 years ago

TI__Guru**** 214387 points

Hello Roberto,

Please also see the code defined by NWK_MANAGER and review the Network Manager section of the Z-Stack User's Guide.

Regards,
Ryan

Zigbee & Thread

Zigbee & Thread forum

CC2652P: Clarification about channels used by ZigBee Network