A Multi-tier, Multimodal Wireless Sensor Network for Environmental Monitoring Carlos Eduardo R. Lopes 1 , Fernando D. Linhares 1 , Michele M. Santos 1 , and Linnyer B. Ruiz 1 Universidade Federal de Minas Gerais (UFMG) Belo Horizonte – MG – Brazil {dlopes,linnyer}@cpdee.ufmg.br, {fernandoduli,mimes}@ufmg.br Abstract. WSNs are distributed sensing tools with monitoring capa- bilities unavailable until now. Network elements (sensor nodes) are fre- quently pointed out as a new computer systems class due to its ubiq- uitous an analytical features. Wireless Sensor Networks have evolved quickly in recent years. Such evolution lead to specializations such as Wireless Visual Sensor Networks and Multi-tier, Multimodal Wireless Sensor Networks (M 2 WSN). The desing, modeling and implementation development of a WSN M 2 for environment monitoring is treated in this work. Simulations with such network shows that they present bet- ter usage of components and energy resources with little sacrifice to the application performance. 1 Introduction Wireless Sensor Networks (WSNs) applications development traditionally are based on a single-tier architecture with homogeneous sensor nodes. One may expect however, a positive behavior from a WSN that makes use of heterogeneous elements organized into different groups or tiers. This work deals with such challenge: the design, modeling and implementation of a Multi-tier, Multimodal Wireless Sensor Network ( M 2 WSN) for environmental monitoring of wild life in remote areas. The development of a M 2 WSN will act as proof of concepts for this WSN specialization. In a WSN M 2 , multi-tier relates to the way the network elements are orga- nized: into hierarchical levels according to their functionalities and capabilities. By multimodal it is meant that different sensing modalities are employed to achieve a common goal [1]. For these networks, from the lower hierarchy tiers till the top ones, an increase on sensor node capabilities (computational power and communication range for example) is expected along with the complexity of the tasks to be performed. Hence, in network deployment constrained elements are densely distributed over the sensing area performing simple tasks, while more capable elements with sparse deployment execute more complex tasks. The M 2 WSNs can present advantages over single tier, unimodal WSNs: lower monetary costs, higher coverage, functionality and reliability. It is not difficult to find a WSN that presents better performance than a M 2 WSN in one of the