*3.4. Security*

The dynamic and flexibility of RWN represent a challenge for implementation of security schemes due to frequent changes in the network status, e.g., sporadic connectivity, variable number of active WDs, temporal topology, etc. In addition, it is desirable to provide authentication and privacy requirements to avoid vulnerabilities due to malicious eavesdropping devices. Commonly, the schemes require associative mechanisms, security protocols which can be proactive or reactive and involve cross layer functions or coding signals [37,38].
