## 2 Background--Related Work  
### Autonomic Characteristics and IP Integration  
Since a common technology is beneficial, the trend in the design and implementation of future networks is the integration of sensors with the existing IP networks. WSNs are usually considered as low-power, wireless personal area networks (LoWPANs). LoWPANs are poised to form the next tier of the Internet by connecting billion of sensor nodes to the Internet and using the existing computing infrastructure [3,16]. Extending IP to LoWPANs was once considered impractical [3] due to the resource-intensive overhead imposed by IP communication to energy-constrained devices. In order to handle these issues, 6 LoWPAN was introduced as an adaptation layer that enables efficient IPv6 communication over 802.15.4 links [3].  
The transition to IP is crucial since it enables the design and deployment of autonomic functionalities in WSNs. IP networking characteristics may be exploited by the network layer in order to be responsive and adaptive while remaining energy-efficient. The deployment of autonomic functionalities is helpful since the protocols and the techniques that are being developed for monitoring and management of WSNs should have minimal configuration, preferably work \"out of the box\", be easy to bootstrap, and enable the network to self heal given the inherent unreliable characteristic of these devices. The basic autonomic functionalities that have to be supported by sensor nodes are [17]:  
* _Self-configuration_: change configuration parameters (e.g., data acquisition rate) according to the conditions in the sensor environment,
* _Self-optimisation_: fine-tune each sensor entity in order to achieve pre-determined goals, while low energy consumption and optimal quality of service have to be guaranteed based on corrective actions,* _Self-healing_: detect system malfunctions or failures and start corrective actions based on defined policies and cooperation among neighbouring nodes to recover the network or a node,
* _Self-protection_: recognize possible sources of problems or threats in the sensor network and take proactive measures,
* _Self-awareness_: sense network changes in the sensor environment and be aware of the capabilities and the status of your neighbours.  
Self-organizing systems completely rely on localized decision processes and nodes have to follow three basic methods in order to implement the desired behaviour; interact with other nodes in their neighbourhood, adapt their local state according to the conditions in their environment, and include probabilistic techniques in their decisions [5,18]. Based on the acquired knowledge, it is desirable that the initial sensor network configuration takes advantage of the underlying physical sensing and topological characteristics so as to assign responsibilities to nodes that are best suited to perform certain sensor network duties [19]. This preliminary assignment of duties facilitates future reorganization of the network in order to easily adapt to any changes.  
Taking into account these considerations, NEURON's mechanisms are designed to operate in a fully autonomic manner. The network entities cooperate and exchange information based on the policies that are applied by these mechanisms. Thus, the sensor network may be self-configured and self-optimised, it supports self-awareness through proper dissemination of information and is able to react to possible failures.