Power Aware Routing功感知路由.pptVIP

Power Aware Computing The concept of power aware computing is to save energy without losing performance. It is the primary focus of designers of portable and battery-powered computing systems. Better management of power translates into longer battery life or into smaller batteries, which in turn implies smaller and lighter devices. The three areas of power aware computing that we will focus on: power aware routing, power aware cache management and power aware microarchitecture. POWER-AWARE ROUTING – James R. Cooper Power Aware Routing In a typical network, the route of a packet will be determined by calculating which path is either fastest, or has the least amount of hops. This may mean that some nodes in the network get far more usage than others. If nodes have a limited power supply, such as portable computers, extreme usage could quickly drain the battery. A temporary mobile network, such as an ad hoc network, would benefit from Power Aware Routing. Examples: Soldiers in the battlefield or rescue workers after a disaster. Power Aware Routing In this network, it is clear that node 6 will receive the most usage, causing its batteries to become quickly depleted. This will cause node 6 to crash, disrupting the network. Other nodes will also quickly crash as they try to absorb the traffic of node 6. PAMAS PAMAS (Power-Aware Multiple Access protocol with Signaling) The basic idea of PAMAS is for a node to power off when it is not needed. A node powers off when It is overhearing a transmission and does not have a packet to transmit. At least one neighbor is transmitting and one neighbor is receiving. (So as not to interfere with neighbors reception.) All neighbors are transmitting and node is not a recipient. A fundamental problem is knowing how long to remain powered off. PAMAS Before a transmission, a node sends a RTS message (ready to send) to the recipient, which replies with a CTS message (clear to send). The RTS and CTS contain the length of th