Ada Audits the Wake-Up Energy Numbers

Ada keeps the RTT budget, radio power, and rounding separate in the wake-up energy claim

ADA · CALCULATION AUDIT

Ada Audits the Wake-Up Energy Numbers

The chapter models a cellular device waking 96 times a day with a 100 ms RTT: HTTP/1.1 spends 33.6 s/day on handshakes versus HTTP/3’s 9.6 s/day, which at 1.11 W radio power is 37.3 against 10.7 J/day — a 71% saving. This audit checks the wake-up energy numbers and bounds what the 71% actually claims: connection overhead, not whole-device battery life.

Companion to the chapter Modern HTTP for IoT — every number here comes from that chapter.

The physics link is the radio active window. Keep the RTT arithmetic separate from the power conversion, then round once at the end so the claimed saving is traceable.

1. Convert the existing RTT example into seconds

The chapter uses 96 wake cycles per day, a 100 ms RTT, and multipliers of 3.5, 2.5, and 1.0:

HTTP/1.1 = 96 x 3.5 x 0.100 s = 33.6 s/day

HTTP/2 = 96 x 2.5 x 0.100 s = 24.0 s/day

HTTP/3 0-RTT = 96 x 1.0 x 0.100 s = 9.6 s/day

2. Convert current and voltage into radio power before multiplying

The existing 300 mA and 3.7 V values give:

P = I x V = 0.300 A x 3.7 V = 1.11 W

Using that full value, the daily handshake energy is:

HTTP/1.1 = 33.6 s x 1.11 W = 37.296 J/day -> 37.3 J/day

HTTP/2 = 24.0 s x 1.11 W = 26.64 J/day -> 26.6 J/day

HTTP/3 0-RTT = 9.6 s x 1.11 W = 10.656 J/day -> 10.7 J/day

3. Compute the reduction from unrounded joules

For the HTTP/1.1 to HTTP/3 comparison:

(37.296 - 10.656) / 37.296 = 0.714285... = 71.4%

The displayed 71% saving is therefore a rounded connection-overhead result. It is not a whole-device battery-life claim until receive windows, retries, payload airtime, sleep current, and failed resumptions are added to the same ledger.

Every number above is taken from this chapter's own worked example and re-derived step by step.