Here we present the results of tha consumption for sending SMSs.



Experiment details


Power consumption when sending SMS using GSM and UMTS networks.



Technology used:


Number of tests:



During the measurements the other air interfaces (BT and WLAN) are switched off.



Text messages sent by using SMS can be encoded in different ways: the default GSM 7-bit alphabet, the 8-bit data alphabet, and the 16-bit UTF-16/UCS-2 alphabet. Depending on which alphabet the text is coded with, the maximum size per SMS is 160 7-bit characters, 140 8-bit characters, or 70 16-bit characters. It is possible to send longer texts by concatenating more messages with each other.

The Figure below shows the results of measurements done by sending messages of different sizes to evaluate how energy consumption is related to the length of the text. The messages were sent using both GSM and UMTS with a SIM card from TeliaSonera in Oulu, Finland.

Energy spent for sending text messages with different length.

We have sent 50 messages for each size and then plotted the average value of the energy spent. The phone was in the same position for all the measurements to have the smallest variation possible in the received signal strength. The plot clearly shows that the energy consumption increases linearly with the length of the message. The messages sent were 8-bit encoded, therefore it is possible  to see some jumps up in the energy consumption when two messages are concatenated, such as between 100-150, 250-300, and 400-450. It is interesting to notice that given a fixed length, sending an SMS using 3G is always more energy consuming than using GSM. The gap varies from 0.6 to 1.4 Joule.
Another interesting relation exists between length of the messages and time needed for sending them. The Figure below shows that the time increases with the growth of the size of the message and that the overall time needed is greater with GSM than with 3G.
Moreover the gap between the two technologies increases linearly with the length of the text.

Time spent for sending text messages with different length using both GSM and UMTS.


The plot in the Figure below shows that the power level for GSM does not vary too much when the size of the text increases, whereas in the 3G case, it grows linearly with the length of the SMS.

Power values for sending SMS of different size using both GSM and UMTS.


Another factor which influences the power, the time, and therefore the energy, is the received signal strength. As shown in the Figure below for both GSM and 3G, when the power of the received signal decreases, the time needed for sending the SMS increases.

Power traces for sending 200 bytes using UMTS and GSM networks. The plot shows two traces for each network with different received signal strength


As shown in the Figure below  the power levels increase as well when the received signal strength decreases and therefore, more energy is needed when the signal is weaker.

Mean power level for sending 200 bytes using UMTS and GSM. The plot shows histograms for different values of received signal strength.

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Last update:27-05-2009