  We consider a single station (STA) in the Power Save Mode (PSM) of an IEEE
802.11 infrastructure WLAN. This STA is assumed to be carrying uplink and
downlink traffic via the access point (AP). We assume that the transmission
queues of the AP and the STA are saturated, i.e., the AP and the STA always
have at least one packet to send. For this scenario, it is observed that uplink
and downlink throughputs achieved are different. The reason behind the
difference is the long term attempt rates of the STA and the AP due to the PSM
protocol. In this paper we first obtain the the long term attempt rates of the
STA and the AP and using these, we obtain the saturation throughputs of the AP
and the STA. We provide a validation of analytical results using the NS-2
simulator.
