Introduction#

The primary focus of this application note is on wireless communication systems and managing interference between Wi-Fi and Zigbee, which operate within the same frequency spectrum. It focuses on addressing the challenges of coexistence and PTA between these two protocols in Internet of Things (IoT) environments. The work also involves leveraging SoC architecture, specifically the SiWG917 SoC, for implementing and testing co-existence strategies in real-world applications.

The coexistence of Wi-Fi and Zigbee in the 2.4 GHz ISM band poses significant challenges due to interference, which can degrade performance, increase latency, and reduce throughput. Wi-Fi is used for high-throughput applications, while Zigbee is designed for low-power and low-data-rate applications. Effective interference management is crucial, especially in IoT environments with multiple devices. PTA is a promising solution that schedules and prioritizes packet transmission to minimize collisions. Integrating PTA into SoC platforms like the SiWG917 SoC can enhance resource management and interference mitigation, ensuring optimal coexistence and improved network performance.

PTA functions as an external coexistence mechanism that is designed to prioritize packet transmissions to reduce collisions between devices using different protocols, such as Thread/Zigbee, Wi-Fi, and BT/BLE. This implementation configures the SiWG917 as the PTA Main to support 3-wire coexistence for Wi-Fi in the 2.4 GHz band. It configures the EFR32MG21 device as the PTA Secondary operating in Zigbee mode.

When both devices operate within the 2.4 GHz band, they may have overlapping channels due to their spatial co-location. To prevent this, specific synchronization between the Zigbee EFR32 devices and Wi-Fi SiWG917 is required to regulate their transmission and reception, ensuring no collisions occur and optimal performance is maintained.

The SiWG917, as the PTA Main, controls transmission timing based on handshake signals exchanged over three GPIO lines. The Zigbee device, acting as the PTA Secondary, triggers these signals based on its transmission requirements.

The current implementation protects Zigbee transmission and reception from interference caused by the SiWG917 operating in Wi-Fi mode. The same mechanism also protects Wi-Fi transmissions from interference caused by the Zigbee device. However, the current implementation does not ensure the protection of Wi-Fi reception, which will be addressed in future enhancements of this feature.