For a specific device connected to specific AP. Can I estimate the differences in radiation power (mWh) depending on the data transmitted (2KB/s vs 200KB/s)?

If so, how?

  • 2
    \$\begingroup\$ Have you read the Wifi spec to determine if there is a relationship? Have you made any measurements? \$\endgroup\$
    – John U
    Commented Mar 14, 2014 at 9:46
  • 1
    \$\begingroup\$ Power would be mW not mWh. mWh could be energy. \$\endgroup\$
    – user16324
    Commented Mar 14, 2014 at 10:48
  • \$\begingroup\$ Transmission power it is not related with bandwidth, but it is related with the receiver sensitivity and modulation schemes (dBm at x Mbps in DFM, QPSK, CCK, OFDM…) at a range of –68dBm to –94dBm. Then you can calculate propagation losses, Tx antenna gain, Transmitter power… \$\endgroup\$
    – GR Tech
    Commented Mar 14, 2014 at 14:49

1 Answer 1


If two radio systems are operating at broadly the same frequency, using the same type of antennas and over the same distance and terrain, a theoretical comparative judgement can be made. The judgement is based on the assumption that a receiver (at a lower data rate) requires less received power at its antenna compared to the receiver operating at the higher data rate.

The required power for a receiver is -154dBm + 10log\$_{10}\$ (bit rate)

Ignoring the -154dBm (because we are making comparisons) it can be seen that: -

10log\$_{10}\$ (200,000) = 53 dBm and

10log\$_{10}\$ (2,000) = 33 dBm

I've ignored "B" (bytes) and assumed "b" (bits) in the equation but it makes no difference; 2 kbps requires a power level at the antenna that is 20 dB smaller than 200 kbps for the same bit error rate.

In real money, that means one-hundredth of the power is required to be transmitted for 2kbps, all other things being equal.


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