earticle

영어

Medium access control protocols for wireless sensor networks are almost always designed to be energy efficient. One mechanism used to reduce energy expenditure is to periodically turn off the radio receivers of the sensor nodes in a coordinated manner. The nodes with radio receivers turned off are said to be in the sleep mode. Nodes form virtual clusters based on common sleep schedules. However, protocols like the widely used S-MAC may require some nodes to follow multiple sleep schedules causing them to wake up more often than the other nodes. This paper demonstrates in some wireless sensor networks using S-MAC, a significant proportion of the nodes may have to stay awake much longer than envisaged. A modification of the protocol is then proposed to eliminate the need for some nodes to stay awake longer than the other nodes. The modified version improves the energy efficiency and increases the life span of a wireless sensor network. The paper concludes with the result of simulation studies which indicate that the use of the proposed protocol is expected to increase the life time of wireless sensor networks significantly.