## 3 Virtualization: A Solution to Some Challenges in WSN
### Security  
The goal of security in any connected and communication system is to ensure authentication of the sender and receiver, confidentiality of the data, integrity of the frame and availability of the network [100]. There is a need to constantly detect and stop attacks in a WSN. Connected IoT devices enable a large number of objects to be connected directly to the internet [101]. This wide exchange of information by connected IoT devices presents an appealing environment that malicious attackers may seek to undermine. Thus, security methods are required as countermeasures. In this regard, cryptographic primitives (public and symmetric key encryption) have been employed to address security threats [102]. The role of the public-key infrastructure (PKI) provides a set of tasks, guidelines and processes. Their function is to generate, allocate, utilize and rescind digital certificates among others functions. Because Symmetric-key encryption [103] method scales at a rapid rate, it thus becomes difficult to store these keys in the sensor node. It also suffers from a poor distribution technique. Public-key cryptography [56] is very complex for implementation in computation and storage limited nodes.  
A new WSN architecture was introduced in [104] that discusses authentication of certificate authorities in WSNs using a public key setup. It works by providing an initial trust key between network nodes. With ECC being WSN-ready [105], it creates a platform for authentication via virtual certificates (AVCA) as discussed in [104]. AVCA provides mechanisms to overcome issues with regards to safeguarding many dispersed networks. It fosters simplicity, interoperability, mitigation of denial of service (DoS) attacks and scalability, which is ideal for VWSN.  
Considering the evolution of VWSNs, the traditional internet security protocols are too resource intensive for integration into the sensor systems. Thus, lightweight security protocols are essential characteristics of any potential solution. Furthermore, security in WSN is tending towards ensuring trusted execution environments (TEE) in which security solutions are provided even from the physical (PHY) level of the OSI model [106; 107]. For example, the ability for hardware partitioning in order to guarantee security suggests that virtual network frameworks can be implemented easily to avoid security attacks. Such end-to-end security approaches are enablers for VWSN. This concept is illustrated in Figure 6.  
In a sensor node chipset, a non-secure world might be defined as a hardware subset consisting of memory regions, caches and specific devices. Thus, non-trusted software can be limited to an  
Figure 6: Non-secure and Secure environment.  
environment that prevents access to, or even knowledge of the additional hardware required to support the architecture in the secure world. TEE offers a secure and locked execution of acute applications in virtualisation environments. Furthermore, system-wide security can also be provided by integrating the trusted region into the processor that interconnects the system peripherals [108; 109]. The switch between the normal and the secured worlds is performed in hardware, thus eliminating the need for a hypervisor/VMM that has processing overhead. This yields real-time performance as well as lower power operation [110].