Estimating the energy cost of communication on portable wireless devices

Software applications running on portable wireless devices communicate with the rest of the network over a wireless link. In these portable devices, the communication cost is a large fraction of the total energy consumption. The amount of energy consumed by the communication component of a portable device mostly depends on different parameters such as packet size and packet rate (or, bit rate). In this paper, we present the results of our investigation of the impacts of these communication parameters on energy consumption. First we build a simple analytic model to estimate the energy consumption due to receiving and transmitting data packets, and then we validate our model by conducting experiments. Results show that the analytical model is effective and gives accurate results. By varying data packet lengths, a communication device consumes different levels of energy to achieve the same data rate. When the packet size is very small compared to the maximum transmission unit (MTU), the device consumes more energy. However, large packets do not necessarily save energy. They rather add some other types of overheads, such as segmentation, recombination, and packet drop. Thus, for a given set of network parameters, an application can choose a suitable data packet length to minimize energy consumption. We also present the impact of data rate and packet delays on energy consumption. These results help us in understanding the energy consumption behavior of a communication device. They also facilitate us in optimizing the energy cost while designing a wireless application.