DDC: Dynamic duty cycle for improving delay and energy efficiency in wireless sensor networks

Due to the limit of computation and storage capability of devices, traditional security techniques face many challenges in the process of data transmission. Networks need to consume more energy and larger transmission for transmitting data in insecure network status. However, it is of great importance to deliver packets to the base station (or sink node) in a timely manner to support the delay-sensitive applications. For Wireless Sensor Networks (WSNs), it is challenging to satisfy end-to-end delay requirements due to the duty cycle adopted by the nodes, which can cause considerable delay because nodes can only transmit or receive information in their active periods (i.e., resulting in sleep delay). To address this issue, a dynamic duty cycle (DDC) scheme is proposed for minimizing the delay in WSNs. Specifically, we firstly investigate how the duty cycle affects the network delay. Then, the DDC scheme is devised to prolong the active period of nodes in non-hotspots areas. With a greater duty cycle, the forwarding node set remains awake with a larger chance. Consequently, the sleep delay of a node decreases, and the transmission delay is reduced. In addition, only the remaining energy of nodes is used to improve the performance. Thus, the DDC scheme does not damage network lifetime. Through analysis and experimental results, it is demonstrated that the DDC scheme can outperform other schemes. Compared with the existing fixed duty cycle (SDC) scheme, the transmission delay in the DDC scheme is reduced by 20-50%, the lifetime is increased by more than 16.7%, and the energy efficiency is improved by 15.3%-16.3%.