Low Power Interoperability Considerations#

  • It is recommended to set the device into Connected Power Save Mode only after IP configuration.

  • If a wireless disconnection happens when the NWP is in Power Save Mode, disable the power save and reconnect to the AP.

  • To avoid interoperability issues with various APs, enable the Enhanced Max PSP feature.

  • For applications where throughput is not a major concern, consider disabling the higher data rates (MCS5, MCS6, and MCS7).

    • To do this, enable BIT(19): SL_SI91X_FEAT_DISABLE_MCS_5_6_7_DATARATES in config_feature_bit_map in the boot configuration.

  • In power save modes, if the DNS requests fail with a few APs, the SL_SI91X_FEAT_AGGREGATION in feature_bit_map is to be enabled in boot configuration. If this does not help, it is recommended to disable the power save and then make a DNS request API call and configure the device back into power save mode.

    • The above recommendation works in case of socket connection failures as well. Beacon Miss Handling - In connected Wi-Fi power-save mode, the SiWG917 NWP sleeps between scheduled wakeups. Depending on the configured power-save mode, the device wakes up at the DTIM interval, Listen Interval, or TWT wake interval. Upon wakeup, it receives the AP beacon, checks the TIM information for buffered data availability, performs any required data exchange, and then returns to sleep.

    • If the SiWG917 wakes up at the expected beacon time but fails to receive a valid beacon, the miss may be caused by channel conditions or timing drift. In such cases, the DUT enters a more conservative mode and starts waking up for every beacon, regardless of the configured DTIM or Listen Interval settings, until a beacon is successfully received.

    • The beacon_miss_ignore_limit field in sl_wifi_performance_profile_v2_t defines the number of consecutive missed beacons that can be ignored before entering this conservative mode. Once the configured limit is exceeded, the device wakes up for every beacon interval irrespective of the DTIM or Listen Interval configuration.

    • This can be configured inside the Wi-Fi performance profile, and then calling the sl-wifi-set-performance-profile-v2 API with the profile. Example: sl_wifi_performance_profile_v2_t profile = {0}; profile.profile = ASSOCIATED_POWER_SAVE; profile.beacon_miss_ignore_limit = 5; sl_wifi_set_performance_profile(&profile); //calling the API

    • The default value is 1, and the recommended range is 1–3. Configuring values greater than 3 may lead to interoperability issues or disconnections.