*Article* **Performance Evaluation and Interference Characterization of Wireless Sensor Networks for Complex High-Node Density Scenarios**

**Mikel Celaya-Echarri 1, Leyre Azpilicueta 1,\*, Peio López-Iturri 2,3, Erik Aguirre <sup>2</sup> and Francisco Falcone 2,3**


Received: 1 July 2019; Accepted: 4 August 2019; Published: 11 August 2019

**Abstract:** The uncontainable future development of smart regions, as a set of smart cities' networks assembled, is directly associated with a growing demand of full interactive and connected ubiquitous smart environments. To achieve this global connection goal, large numbers of transceivers and multiple wireless systems will be involved to provide user services and applications anytime and anyplace, regardless the devices, networks, or systems they use. Adequate, efficient and effective radio wave propagation tools, methodologies, and analyses in complex indoor and outdoor environments are crucially required to prevent communication limitations such as coverage, capacity, speed, or channel interferences due to high-node density or channel restrictions. In this work, radio wave propagation characterization in an urban indoor and outdoor wireless sensor network environment has been assessed, at ISM 2.4 GHz and 5 GHz frequency bands. The selected scenario is an auditorium placed in an open free city area surrounded by inhomogeneous vegetation. User density within the scenario, in terms of inherent transceivers density, poses challenges in overall system operation, given by multiple node operation which increases overall interference levels. By means of an in-house developed 3D ray launching (3D-RL) algorithm with hybrid code operation, the impact of variable density wireless sensor network operation is presented, providing coverage/capacity estimations, interference estimation, device level performance and precise characterization of multipath propagation components in terms of received power levels and time domain characteristics. This analysis and the proposed simulation methodology, can lead in an adequate interference characterization extensible to a wide range of scenarios, considering conventional transceivers as well as wearables, which provide suitable information for the overall network performance in crowded indoor and outdoor complex heterogeneous environments.

**Keywords:** wireless sensor networks; interference characterization; performance evaluation; 3D ray launching; high-node density; smart cities
