## 4 A Comprehensive Survey and Related Works
It presents a comprehensive review of various vendor models, categorized into low-end, middle-end and high-end devices based on features such as computational power, memory and storage. This study highlights the rapid technological advancements, including sensor technology, in embedded IoT board development. This provides a crucial informational foundation for implementations and adoption in the Smart Building use case of this research. Moreover, as a complement to this article and with a focus on network management, there is the article [40] exploring IoT low-power network management and the client-server protocol LWM2M applied to the IoT world. Subsequently, [PERSON] et al. [26] propose a VIoT framework, aiming to integrate VoIP with advanced services such as unified communication, collaboration and omnichannel capabilities. This integration leverages high-performance IoT devices exceeding the capabilities of the middle-end devices described in the previous study, incorporating video calls (audio and video). The authors innovatively explore the convergence of VoIP protocols and IoT device challenges, proposing an integrated architecture by bridging the communication protocols of both domains. This approach informs the design of the virtual concierge and novel VIoT intercom system, with or without video, for security and communication within the SB case study. The authors also detail a mechanism for implementing a VIoT gateway by adding an SIP client to facilitate this integration of two worlds. The major knowledge gap identified in the literature review of this section is that, currently, there are few studies that delve into the adoption of SDN and SD-WAN, and the NFV offered by Service Providers (current focus on NFV and 5G network) for use cases such as those of the SBs in the present study. Furthermore, there are few studies on the integration of SDN and NFV with smart IoT devices and their communication protocols, such as WSN, LoRa, routing and mesh protocols for IoT device and VIoT, already implemented in buildings (SBs or some partially intelligent) at the edge. The following articles are focused on IoT-5G and network-slicing: [7; 30; 40; 41; 42]. It is noted that the referenced literature [2; 3; 10; 13; 41] presents many segregated studies, such as cloud solutions and their distributed microservices architecture, Fog and Intelligent Edge Computing (IEC) with advantages over the traditional on-premise Data Center, security of SBs, SDN and SD-WAN replacing MPLS-VPN in new implementations by service providers, multimedia applications (video, streaming and voice over IP) optimized for jitter, latency and packet loss in Internet communication using the protocols mentioned in Section 3 for other use cases, such as the industrial one. However, there are some gaps in the integrated proposal and implementation of the above technologies that aims to discuss and guide towards feasible solutions and a good cost-benefit ratio for the condominiums of metropolitan buildings, an important aspect covered by the present study. For example, the review of the network and application management layer critical to this user regarding the SDNs, Fog and Intelligent Edge Computing technologies integrated with the smart IoTs of the user layer is part of the process.