WiFi: consumption for different sates

Here we present results for measurements regarding data communication using WiFi.

 

Experiment details

 

Description:

Measurements of power consumption of WLAN in infrastructure mode for different states.

Place:

Indoor

Technology used:

IEEE 802.11b/g.

Number of tests:

50

Notes:

During the measurements all the other air interfaces (BT and Cellular) are switched off. The distance from the AP is approximately 3-5 meters.

 

 

Infrastructure Mode

The Figure below shows the values of power consumption of WLAN when used in Infrastructure mode for:

  • Connection: Turn on WLAN and connect to the Access Point .
  • Disconnection: Disconnecting from the AP and turning WLAN off.
  • Idle: Being connected to the AP and in idle mode.
  • Idle in saving mode: Being connected to the AP without transmitting nor receiving data and in saving mode.

 

 

Power consumption for WLAN in different states when used in infrastructure mode.

Ad hoc mode

The measurement environment was a public location at Aalborg University,
Denmark. The location was a 400 m^2 three storage high indoor open facility
surrounded by offices, meeting and lecture rooms. In all tests two Nokia N95s
were used, one acting as server and one client. The phones communicated using the internal IEEE 802.11b/g radio, over which an amount of 2MB was transferred from the server to the client using TCP. Other factors affecting data rate such as interference is not considered in this measurement. However, to
reduce the effect of temporal changes, the tests were reproduced during
different times of the day e.g. at night where the building were vacated and
a midday where the offices were busy. The test was conducted in two stages. The first stage was conducted using two fixed setups, this was done to allow reproducibility. The purpose of the second stage was to verify the results of stage one, this was done by selecting random locations for both server and clients. At each random location devices were oriented randomly to represent an users actual use of a device. The random orientation also reduced the advantage for any antenna gain with respect to a particular orientation.

In Figure below the achieved datarate are plotted against the distance between the two phones. The highest datarate is reached when the phones are standing at a distance of 3 meters (the minimum we have measured).

 

Datarate achieved at different distance when downloading 2 MB of data using WLAN in ad-hoc mode.

 

In Figure below the total energy spent for downloading is plotted against the distance between the two phones. The lowest energy consumption takes place when the phones are standing at a distance of 3 meters.

Energy consumption for different distances between the phones when downloading 2 MB of data using WLAN in ad-hoc mode.

Parametrized model

 

Energy = P_action * Duration

 

Action P_action [mW]

On connection

868.50

On disconnection

134.82

Connected not tx nor rx

58.372

Connected not tx nor rx (saving mode)

26.36

 

Department of Electronic Systems | Aalborg University | Niels Jernes Vej 12 | DK-9220 Aalborg | Denmark
Phone: (+45) 9635 8695 | Fax (+45) 9815 1583 | E-mail ies(at)ies.aau.dk
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Last update:20-07-2011