Conclusions#
Co-located, strong Wi-Fi can have a substantial impact on Bluetooth and 802.15.4 performance. It can be improved by using the following unmanaged coexistence techniques:
With market trends toward higher Wi-Fi TX power, higher Wi-Fi throughput, and integration of Wi-Fi, Bluetooth, and other radios, into the same device, unmanaged techniques alone may prove insufficient, so a managed coexistence solution is required. Even with a managed coexistence solution, all unmanaged coexistence recommendations are still necessary.
Silicon Labs recommends the following managed coexistence strategies:
Wi-Fi/PTA devices providing 802.15.4-derived Packet Traffic Arbitration.
Silicon Labs’ EFR32 PTA solution:
Implement one to four GPIOs as a combination of REQUEST, GRANT, PRIORITY, and RHO (two additional GPIOs are required to implement the PWM with High-Duty Cycle Wi-Fi feature for multi-EFR32 configurations).
Supports both single-EFR32 and multi-EFR32 configurations with single Wi-Fi/PTA interface.
Silicon Labs’ coexistence library and coexistence-hal-config.h #define settings to configure EFR32 PTA support for available GPIO pins and for compatibility with the chosen Wi-Fi/PTA device.
Silicon Labs’ API, supporting run-time PTA reconfiguration. For more information, see Zigbee and OpenThread Coexistence with Wi-Fi or Bluetooth Coexistence with Wi-Fi.
Bluetooth#
Wi-Fi/Bluetooth coexistence test results show substantial Bluetooth performance improvements when PTA is utilized:
Connection stability
Prevent user frustration with unstable product function as Wi-Fi throughput varies.
Substantially reduced message failure with associated throughput improvement:
Improves end-node battery life.
Reduces message latency.
Bluetooth remains operational, even during high Wi-Fi duty cycles.
802.15.4#
Wi-Fi/802.15.4 coexistence test results show substantial 802.15.4 performance improvements when PTA is utilized:
Improved device join success:
However, device join utilizes broadcast messages, which are not retried.
If possible, device join success can be further improved by temporarily reducing Wi-Fi traffic during devices joining 802.15.4 network.
Substantially reduced MAC retries:
Reduces message latency.
Improves end-node battery life.
Frequency separation remains important, as best managed coexistence performance is for “far-away” channels.
Substantially reduced message failure:
802.15.4 network remains operational, even during high Wi-Fi duty cycles.