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

Experiment details

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.

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).

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.