Setup Hardware: Nordic nRF7002DK as Wi-Fi STA (client) . AP & Receiver: a Linux PC creates a Wi-Fi Hotspot/SoftAP (NetworkManager/hostapd) and simultaneously runs the UDP receiver on the same machine. Traffic: the STA streams the same JPEG image repeatedly over UDP ; only the RF band changes ( 2.4 GHz vs 5 GHz ). Power: system powered at 3.3 V , measured with a precision current monitor (PPK-style). Environment: near-water/underwater test; the transmitter is progressively submerged. Water depths: air, 0, −2, −4, −6, −8, −10 cm . Controls: same AP, scripts, STA role, TX power , and payload across runs; only the band differs. Observation With increasing depth, 2.4 GHz shows higher average power and lower/more jittery throughput . 5 GHz remains lower and steadier in power with relatively stable throughput. (Plots attached.) I expected 2.4 GHz not to be worse than 5 GHz near water due to the longer wavelength. Instead I see higher power and higer throughput decrease on 2.4 GHz. Questions What mechanisms could make 2.4 GHz draw more power than 5 GHz in STA mode under these conditions? Why would throughput on 2.4 GHz fall too much? Any band-specific rate control / fallback behaviors that explain this? Thanks!

Why does 2.4 GHz draw more power than 5 GHz in STA mode (underwater test), while throughput drops?

Ziyao Zhou 7 months ago

Setup

Hardware: Nordic nRF7002DK as Wi-Fi STA (client).
AP & Receiver: a Linux PC creates a Wi-Fi Hotspot/SoftAP (NetworkManager/hostapd) and simultaneously runs the UDP receiver on the same machine.
Traffic: the STA streams the same JPEG image repeatedly over UDP; only the RF band changes (2.4 GHz vs 5 GHz).
Power: system powered at 3.3 V, measured with a precision current monitor (PPK-style).
Environment: near-water/underwater test; the transmitter is progressively submerged. Water depths: air, 0, −2, −4, −6, −8, −10 cm.
Controls: same AP, scripts, STA role, TX power, and payload across runs; only the band differs.

Observation

With increasing depth, 2.4 GHz shows higher average power and lower/more jittery throughput.
5 GHz remains lower and steadier in power with relatively stable throughput. (Plots attached.)

I expected 2.4 GHz not to be worse than 5 GHz near water due to the longer wavelength. Instead I see higher power and higer throughput decrease on 2.4 GHz.
Questions
1. What mechanisms could make 2.4 GHz draw more power than 5 GHz in STA mode under these conditions?
2. Why would throughput on 2.4 GHz fall too much? Any band-specific rate control/fallback behaviors that explain this?
  
  Thanks!

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