Energy Management Techniques for WSNs (1): Duty-Cycling Approach

Abstract

Along this chapter, duty-cycling is methodically described and categorized, protocols are analyzed and compared. As abundantly detailed, duty-cycling can be achieved through two different and yet complementary approaches; specifically, topology control and power management. Topology control is by finding the optimal subset of nodes that guarantee connectivity. This scheme exploits node redundancy, which is typical in WSNs, and adaptively selects only a minimum subset of nodes to remain active for maintaining connectivity. Nodes that are not currently needed for ensuring connectivity can go to sleep and save energy. Therefore, the basic idea behind topology control is to exploit the network redundancy to prolong the network longevity, typically increasing the network lifetime by a factor of 2–3 with respect to a network with all nodes always ON. Topology control protocols encompasslocation-driven protocols and connectivity-driven protocols. Power management is by operating duty-cycling on active nodes. Active nodes are those selected by the topology control protocol; they do not need to maintain their radio continuously ON. They can switch OFF the radio, by putting it in the low-power sleep mode, when there is no network activity, thus alternating between sleep and wakeup periods.