Combining Paging with Dynamic Power Management Carla F. Chiasserini, Ramesh R. Rao Presentation and Review by Solomon Bien

Contributions Power management scheme for wireless, battery-powered devices Solves problem of spending too much energy powering up/down devices Allows for tradeoff between energy savings and communications QoS

Dynamic Power Management Device enters successively deeper states of sleep Being in a deeper state requires less power Waking from a deeper state requires more power and takes more time Scheme ensures that device remains in a sleep state long enough for energy savings to be realized

DPM (cont.) Each state corresponds to a power consumption level L 1 L-3 L-1 L-2 W 1,L,P t 1,L W L-1,L,P t L-1,L W L-2,L,P t L-2,L W L-3,L,P t L-3,L T (q) L-1 T (q) L-2 T (q) L-3 T (q) L-4 T (q) 1 W l,m is the delay overhead to go from state l to m P t l,m is the power consumption overhead to go from state l to m T l is the amount of time passed in the sleep cycle before a move can be made into state l This diagram is the recreation of one in the paper.

Paging To contact a device, base station computes its state transition times, then sends paging signals Device wakes up when it receives a paging signal AND it has spent the minimum time in its current state Base station sends data, device acknowledges data, other devices go back to sleep

Results Power savings is exchangeable with delay (adaptive fidelity) Four different sleeping patterns Mean packet delay increases as sleep time and deepness of sleep state increase Power consumption increases with less sleep time and shallow sleep states Lower consumption for larger group of users

Contributions (again … ) Power management scheme for wireless, battery-powered devices Solves problem of spending too much energy powering up/down devices Allows for tradeoff between energy savings and communications QoS

Not bad, but … What is the application for this? Assumptions made about determinism of data arrivals — why not go into a deep sleep right away? How would a gradual wake-up fit in? How do devices decide if they ’ ve spent enough time in their current state before waking up?

… also … Not good for routing (QoS) — but they don ’ t claim it is … Results Should have described simulations more Should attempt explanation/ACK of results Graphs are “ connect-the-dots ” Not written very well Sloppy math and false statements