The BLE coexistence functionality in the SimpleLink™ CC3x35 family of solutions helps in designing a product that uses both Wi-Fi® and BLE. Although the mechanism is designed to implement coexistence with any BLE device, this document also describes the implementation of the mechanism with Texas Instruments™ SimpleLink™ CC26xx ultra-low power wireless MCU for Bluetooth® low energy.
BLE and Wi-Fi® operate on the same frequencies, and disturb each other’s transmissions and receptions, with no inherent way to avoid it.
Wi-Fi® , however, is more inherently tolerant of time-domain disturbances. With this in mind, the coexistence mechanism gives priority to the BLE entity over the Wi-Fi® , as the Wi-Fi® can often delay its transmission or miss a reception, without having any major noticeable effect apparent to the user (to some extent). This is done by connecting the GPIO used by BLE, to control the RF switch to the Wi-Fi® device. This GPIO goes high during any BLE RF activity (transmission or reception), signaling the Wi-Fi® to delay pending transmissions until the signal goes down. A second GPIO may optionally be used when an RF switch is included in the design for a single-antenna use-case. This second GPIO is used to control the RF switch. See Figure 1 for an overview of the implementation.
From a Wi-Fi® perspective, the co-existence mechanism resides in ROM, thus it does not require anything from the user-application, apart from enabling or disabling it through a user API, or pre-programming it using the programming tool.
Because the BLE operates only on the 2.4-GHz band, the co-existence mechanism does not affect the 5-GHz band. Wi-Fi® can operate normally on the 5-GHz band while the BLE works on the 2.4-GHz band without any mutual interference; thus a co-existence mechanism is not required.