Early Wake-Up Ahead Node for Fast Code Dissemination in Wireless Sensor Networks

With the development of sensor-clouds, the traditional WSN is expanded and the computing capacity is greatly improved. However, there are still challenges to be solved in sensor-clouds, such as how to disseminate codes to all nodes in a fast and energy-saving way. In this paper, an early wake-up ahead (EWA) code dissemination scheme is proposed to disseminate codes more efficiently. The main innovations of EWA code dissemination scheme are as follows: (a) An early wake-up message (EWM) routing protocol is proposed to propagate the early wake-up message ahead to awake the nodes in the routing path before data packets arrive. The forecast message can be forwarded for multi-hops during a time slot, while the packet can only be forwarded for one hop. Therefore, the nodes in the routing path can be awakened before the sending node starts to transmit the packets, the sleep latency is thus reduced as the sending node has not to wait for the receiver to be awakened for transmission. (b) The proposed EWA scheme aims at accelerating the code dissemination by increasing the duty cycle of the nodes which are far from the sink based on the EWM routing protocol. Meanwhile, the EWA scheme can improve the energy utilization rate without affecting the network lifetime. Theoretical analysis has verified the proposed protocol and scheme do accelerate code dissemination and improve energy utilization ratio. The experimental results show that the proposed EWA scheme reduces the network delay by 16.53%-37.13% compared to the conventional schemes.