# Novel Approach Sizing and Routing of Wireless Sensor Networks for Applications in Smart Cities
## 2 Related Work  
The present work proposes models based on the optimization of the sizing and routing of telecommunications resources in order to achieve connectivity between wireless sensors, concentrators, and the central offices of public or private companies. Figure 1 emphasizes the complete process required for the deployment of a WSN. Earlier work presented classical wireless sensor network routing solutions, including the novelties of reducing energy consumption with short-range wireless technologies. In addition, hardware prototypes concerned with the interoperability of communication protocols among wireless sensors were presented [4; 16]. However, routing can create various logical topologies according to the need for scalability and the use of multi-layers depending on the number of nodes and the physical complexity of the network [17]. There have been contributions to sensor fault location and applications for the reconstruction of a sampled signal with a percentage of measured data through compressed sensing techniques, as presented by [18]. Other contributions sought to improve the quality of service in packet forwarding by using multi-hop delays, and other work addressed the types of wireless sensor networks employed in the IoT. In addition, it is essential to remember that all applications must be scalable, as noted in [19]. There were also contributions to the dimensioning of wireless sensor networks, as presented in [20]. Furthermore, when deploying a wireless network for smart cities, for more sensors to be incorporated daily to generate new services, the WSN must be flexible, and the proposed algorithms must converge to the optimal solution on time for fast management. The authors note the possibility of using RFID-enabled sensors in an unlicensed band, which can reduce the costs for such applications; however, the interoperability between devices from various manufacturers is not open, and this type of technology was first proposed for electricity metering and for rubbish collection in smart cities. Other work related to IEEE 802.15.4 (Zigbee) offered alternatives for the achievement of the rapid deployment of a wireless communications network and presented the possibility of implementing network topologies that support various types of topologies, such as star, extended star, or mesh topologies. In addition, other work proposed heterogeneous solutions that sought to ensure that investment in communications infrastructure was minimal. The proposals were hybrid networks based on fiber-optic and wireless networks--called FiWi--or networks based on WiFi and Zigbee [21]. Regarding the technologies for WSNs, data concentrators are gateways, and are also used in LPWAN technologies; therefore, the process of optimal network sizing can also be modeled to adequately locate these concentrators with the same rigor as that in the technologies discussed in the previous paragraph [22]. A routing analysis will determine the technology used in order to interconnect the DAPs required in the WSN's deployment while considering a star topology among the sensor nodes and gateways. There are works where the optimization problems were relaxed with clustering, and these were presented in [23; 24; 25; 26; 27; 28; 29]. Figure 1: Geo-referenced sizing and routing of wireless sensor networks. The optimization problem is of the combinatorial type due to its complexity, and it is called an NP-complete problem. Consequently, some authors proposed heuristic algorithms to explore local optimization solutions that are close to the global solution. On the other hand, there was risk in different works that presented the use of clusters. There were sensors without connectivity in their proposed solutions, even though they previously managed to minimize the cost of energy consumption [23; 24]. Methods such as k-means or Kmedoids are not balanced or give multiple answers.