No abstract

Five percent to 25% of power could be wasted before it is delivered to the computational resources on a die, due to inefficiencies of voltage regulators and resistive loss. The power delivery could benefit if, at the same power, the delivered voltage increases and the current decreases. This article presents CoreUnfolding, a technique that leverages voltage Stacking to improve power delivery efficiency. Our experiments show that about 10% system-wide power can be saved, the voltage regulator area can be reduced by 30%, di/dt improves 49%, and the power pin count is reduced by 40% (≈20% reduction in packaging costs), with negligible performance degradation.

No abstract

The increase demand for Quality of Service (QoS) in computer networks and the recent popularization of wireless networks required a standard to bring QoS to such networks. The IEEE 802.11e, a complement to the 802.11 family, answers to these requirements implementing such QoS mechanisms. The main contribution of this work is to provide an evaluation of the final IEEE 802.11e standard. Using the ns-2 simulator, we compare it against IEEE 802.11a with a FIFO queue, as well as priority and round robin arbiter queues. We also consider different scenarios, both in ad hoc and infrastructure modes. Our results show that the IEEE 802.11e can improve the QoS of a wireless network in all scenarios.