Energy-efficient distributed algorithms

for wireless ad hoc networks

Ramki Gummadi (MIT)

CW 2008 2

Protocols: Two traditional areas

Battery conservation for ad hoc n/w• Disconnected routing, forwarding

• Energy-efficient multicast

Sensor networks• Energy-aware communication

• Data-centric storage

• Data-centric routing

CW 2008 3

Energy-efficiency claims

No good way to measure energy communication• Measuring energy at the radio?

• Measuring energy consumed by sensors?

Packetized abstraction for radios• Power consumption of real radios is non-

linear function of message count or distance

CW 2008 4

New approaches

Low-power listen• Make MAC long

• Synchronize on wake-ups

Communication by silences• Sender and receiver wait for n clock cycles to

communicate data value n

• Linear in value of n

CW 2008 5

In-network computing algorithms

Store data within network• Data-centric Storage

(DCS)

• Rendezvous based on mapping data values to nodes

Good for continuous queries, bad for one-shot queries

CW 2008 6

In-network computing algorithms (contd..)

Route queries to internal nodes instead of collecting data at a central server

Lots of papers (Starting from Directed Diffusion)

Hard to deal with failures, data integrity

temp=70

CW 2008 7

Challenge for energy-efficient algorithms

Mismatch between app requirements and protocol guarantees• Sensor networks want data integrity

guarantees Requires all data to be transported out of the

sensor network

For bulk data, use faster radio with higher power, range or lossy multi-hop?