The PEGASIS Protocol PowerEfficient GAthering in Sensor Information

The PEGASIS Protocol • Power-Efficient GAthering in Sensor Information Systems. • The key idea in PEGASIS is to form a chain among the sensor nodes so that each node will receive from and transmit to a close neighbor. 2

PEGASIS - Chain • The nodes will be organized to form a chain, which can either be accomplished by the sensor nodes themselves using a greedy algorithm starting from some node. • When a node dies, the chain is reconstructed in the same manner to bypass the dead node. 3

PEGASIS - Leader • The main idea in PEGASIS is for each node to receive from and transmit to close neighbors and take turns being the leader for transmission to the BS. • Nodes take turns transmitting to the BS, and we will use node number i mod N (N represents the number of nodes) to transmit to the BS in round i. 4

PEGASIS - Token • Token passing approach N 0 N 1 N 2 BS Token Data 5 N 3 N 4

PEGASIS • An enhancement over the LEACH protocol is a near optimal chain-based protocol • Increase the lifetime of each node by using collaborative techniques • Allow only local coordination between nodes and the bandwidth consumed in communication is reduced [1]S. Lindsey and C. Raghavendra, “PEGASIS: Power-Efficient Gathering in Sensor Information Systems, ” IEEE Aerospace Conf. Proc. , 2002, vol. 3, 9– 16, pp. 1125– 30. 51 6

PEGASIS • Drawbacks: Ø assumes that each sensor node is able to communicate with the BS directly Ø assumes that all sensor nodes have the same level of energy and are likely to die at the same time Ø the single leader can become a bottleneck. Ø excessive data delay 51 7

Comparison between PEGASIS and SPIN • PEGASIS saving energy in several stages ØIn the local gathering , the distance that node transmit ØThe amount of data for CH head to receive ØOnly one node transmits to BS 51 8