silabs.com | Building a more connected world. Rev. 2.1
AN1017: Zigbee
®
and Silicon Labs
®
Thread
Coexistence with Wi-Fi
®
This application note describes the impact of Wi-Fi on Zigbee and
Silicon Labs Thread and methods to improve coexistence with Wi-
Fi. These techniques are applicable to the EFR32MGx family. First,
design considerations to improve coexistence without direct
interaction between Zigbee/Silicon Labs Thread and Wi-Fi radios
are described. Next, Silicon Lab’s Packet Traffic Arbitration (PTA)
support to coordinate 2.4 GHz RF traffic for co-located
Zigbee/Silicon Labs Thread and Wi-Fi radios is described. Finally,
methods for using the coexistence CLI commands are discussed.
This application note describes EFR32 Zigbee and Silicon Labs Thread coexistence sup-
port for EmberZNet PRO 6.7.3.0 and Silicon Labs Thread 2.10.1.0. See section 8 Docu-
ment Revision History for a summary of key changes in previous revisions of this applica-
tion note.
Additional details about the implementation of managed coexistence are included in
AN1243: Timing and Test Data for EFR32 Coexistence with Wi-Fi, available under non-
disclosure from Silicon Labs technical support.
KEY POINTS
• Wi-Fi impact on Zigbee/Silicon Labs
Thread
• Improving unmanaged coexistence
• Implementing managed coexistence
• Using the coexistence CLI commands
The information in this document is based on the SLThread implementation of Thread. SLThread reached ‘end of
service’ in December 2019. Silicon Labs is replacing SLThread with an implementation of the more popular Open-
Thread. We anticipate that the results from OpenThread will be very close to the SLThread results.
AN1017: Zigbee® and Silicon Labs® Thread Coexistence with Wi-Fi®
Table of Contents
silabs.com | Building a more connected world. Rev. 2.1 | 1
Table of Contents
1. Introduction ......................................................................................................................................... 3
2. Wi-Fi Impact on Zigbee/Silicon Labs Thread .................................................................................... 4
3. Unmanaged Coexistence .................................................................................................................... 8
3.1. Implement Frequency Separation .................................................................................................. 8
3.2. Operate Wi-Fi with 20 MHz Bandwidth ........................................................................................... 8
3.3. Increase Antenna Isolation ............................................................................................................. 8
3.4. Use Zigbee/Silicon Labs Thread Retry Mechanisms ...................................................................... 9
3.5. Remove FEM (or Operate FEM LNA in Bypass) ............................................................................ 9
4. Managed Coexistence ....................................................................................................................... 10
4.1. PTA Support Options ................................................................................................................... 10
4.1.1. 1-Wire PTA.............................................................................................................................. 12
4.1.2. 2-Wire PTA.............................................................................................................................. 12
4.1.3. 3-Wire PTA.............................................................................................................................. 12
4.1.4. 4-Wire PTA.............................................................................................................................. 12
4.1.5. Multiple EFR32s Connected to Wi-Fi/PTA ............................................................................... 12
4.1.6. Wi-Fi/PTA Considerations ....................................................................................................... 14
4.1.6.1. Wi-Fi/PTA Supports Wi-Fi TX Pre-emption .................................................................... 14
4.1.6.2. Wi-Fi/PTA Prevents Wi-Fi Transmit when GRANT Asserted .......................................... 14
4.1.6.3. Wi-Fi/PTA and Application Implements Reasonable Prioritization .................................. 14
4.1.6.4. Wi-Fi/PTA Implements Aggregation ............................................................................... 14
4.1.6.5. Wi-Fi/PTA Supports Directional PRIORITY .................................................................... 15
4.1.7. TX PRIORITY Escalation ........................................................................................................ 15
4.1.8. PWM for High Duty Cycle Wi-Fi ............................................................................................... 15
4.1.8.1. Background ................................................................................................................... 15
4.1.8.2. PWM Feature Description .............................................................................................. 16
4.1.8.3. PWM Implementation..................................................................................................... 17
4.1.9. Directional PRIORITY ............................................................................................................. 18
4.1.9.1. Single-EFR32 PTA with Directional PRIORITY .............................................................. 18
4.1.9.2. Multi-EFR32 PTA with Directional PRIORITY ................................................................ 20
4.2. PTA Support Software Setup ....................................................................................................... 22
4.2.1. AppBuilder Configurable Options ............................................................................................ 24
4.2.1.1. REQUEST ..................................................................................................................... 24