Performance analysis of sleep mode mechanisms in the presence of bidirectional traffic

Short battery life being a major impediment to a more widespread use of wireless devices, industry standards like WiMAX and 3GPP Long Term Evolution (LTE) embed power saving mechanisms in their protocol stack. Trading in network delay performance for extended battery life, these mechanisms require a careful balance to optimize overall network performance. Therefore, this paper assesses the impact of these mechanisms on network delay performance and battery life, thereby refining existing performance studies of the power saving mechanisms. In particular, this paper explicitly takes into account presence of both downlink and uplink traffic and their influence on the power saving mechanism. This contrasts with previous studies, where the analyses only accounted for downlink traffic. We obtain numerically efficient procedures to compute packet delay as well as energy efficiency characteristics under Markovian traffic. Then, performance of power saving is investigated by some numerical examples. Our results clearly indicate that uplink traffic heavily impacts the energy efficiency of the power saving mechanism.