< SIGs | PowerManagement
Wifi Transmission Speed and Power Consumption
The test is aimed at the relation between power consumption and transmission speed using wifi connection.
Hardware
Lenovo ThinkPad W510 * CPU: Intel Core i7 Q820 1,73 GHz * disk: SATA Seagate ST9500420AS * wifi: Intel Centrino Ultimate-N 6300 * ethernet: Intel 82577LM * GPU: nVidia Quadro FX 880M * OS: Fedora 14 x86_64
Test description
This test was done by using this very simple skript with different arguments values:
#!/bin/sh
while [ true ];
do
wget --limit-rate="$2" -O /dev/null "$1"
done
exit 0
and measuring power consumption with Voltcraft Energy Monitor 3000. Since it uses /dev/null there are no side-effects caused by writing to disk. I have tried to make idle state as much stable as it was possible though there were some fluctuations negativly affecting the precision of the measurement. I have used Lighttpd running on another computer in the same wireless network and these four download speeds:
- 50 kB/s
- 300 kB/s
- 500 kB/s
- 700 kB/s
Results
| speed [kB/s] | Power Drain Increase[W] |
|---|---|
| 50 | 1.50 |
| 300 | 4.02 |
| 500 | 4.79 |
| 700 | 4.92 |
Conclusion
As can be seen from the above data the power consumption increase while using wifi depends on the speed of transmission. Although the power consumption is rising while using faster transmissions the difference is definitely not as big as the difference of time needed to get the data. So the best way is to use as highest speed as possible and get the data in the shortest time letting the power consumption to decrease back as soon as possible.