Abstract : The paper presents GREENNET, an energy efficient and fully operational protocol stack for IP-enabled Wireless Sensor Networks based on the IEEE 802.15.4 beacon-enabled mode. The stack runs on a hardware platform with photovoltaic cell energy harvesting developed by STMicroelectronics that can operate autonomously for long periods of time. GREENNET integrates several standard mechanisms and enhances existing protocols, which results in an operational platform with the performance beyond the current state of the art. In particular, it includes the IEEE 802.15.4 beacon-enabled MAC integrated with lightweight IP routing for achieving very low duty cycles. It offers an advanced discovery scheme that accelerates the process of joining the network and proposes an adaptation scheme for adjusting the duty cycle of harvested nodes to the available energy for increased performance. Finally, it supports security at two levels: a basic standard secure operation at the link layer and advanced scalable data payload security. The paper describes all techniques and mechanisms for saving energy and operating at very low duty cycles. It also provides an evaluation of the performance and energy consumption of GREENNET.
