An experimental study of TCP over IEEE 802.11b power-saving mode
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Reducing the power consumption of battery operated devices has become increasingly important. One way to do this is to reduce energy consumption of the network card The IEEE 802.11 power saving mode is a standard specified for this purpose; it can be used by a network card using IEEE 802.11 to save energy. Although theoretically PSM reduces significantly the power consumption of of the network card, the interaction between TCP and PSM has not been fully explored. In this thesis, we investigate TCP performance over PSM in terms of two aspects: the energy consumption on the client and the transmission time overhead. Our results show that the transmission time overhead depends on the network conditions, mostly the the location of bottleneck link and the TCP connection round-trip time. In some cases, transmission time overhead is significantly more than predicted by previous models. We have also investigated the behaviour of PSM in the case of multiple clients sharing the wireless link. Our results under this scenario show that the amount of energy saved when using PSM largely depends on the competing traffic and decreases as the number of flows increase.