Chapter 4. API Guides
APSTA BGN BG B BGNLR BGLR BLR LR
BGN BGN BG B BGN BG B
•
BG BG BG B BG BG B
•
B B B B B B B
•
BGNLR
• • •
BGNLR BGLR BLR LR
BGLR
• • •
BGLR BGLR BLR LR
BLR
• • •
BLR BLR BLR LR
LR
• • •
LR LR LR LR
In above table, the row is the Wi-Fi mode of AP and the column is the Wi-Fi mode of station. The “-”indicates
Wi-Fi mode of the AP and station are not compatible.
According to the table, we can conclude that:
• For LR enabled in ESP32-S2 AP, it’s incompatible with traditional 802.11 mode because the beacon is sent
in LR mode.
• For LR enabled in ESP32-S2 station and the mode is NOT LR only mode, it’s compatible with traditional
802.11 mode.
• If both station and AP are ESP32-S2 devices and both of them enable LR mode, the negotiated mode supports
LR.
If the negotiated Wi-Fi mode supports both traditional 802.11 mode and LR mode, it’s the Wi-Fi driver’s re-
sponsibility to automatically select the best data rate in different Wi-Fi mode and the application don’t need to care
about it.
LR Impacts to Traditional Wi-Fi device The data transmission in LR rate has no impacts on the traditional Wi-Fi
device because:
• The CCA and backoff process in LR mode are consistent with 802.11 specification.
• The traditional Wi-Fi device can detect the LR signal via CCA and do backoff.
In other words, the impact transmission in LR mode is similar as the impact in 802.11B mode.
LR Transmission Distance The reception sensitivity of LR has about 4 dB gain than the traditional 802.11B
mode, theoretically the transmission distance is about 2 to 2.5 times the distance of 11B.
LR Throughput The LR rate has very limited throughput because the raw PHY data rate LR is 1/2 Mbits and 1/4
Mbits.
When to Use LR The general conditions for using LR are:
• Both the AP and station are devices.
• Long distance Wi-Fi connection and data transmission is required.
• Data throughput requirements are very small, such as remote device control, etc.
Espressif Systems 1535
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