## 5 Conclusions  
This paper has experimentally assessed the effects of the mesh area on localization accuracy for a distributed indoor localization system based on a constellation of four anchors composed of switched beam antennas and capable to acquire communication link RSSI, [15; 16]. Due to its direct interoperability with an IEEE 802.11x/802.15.4 radio access technology, in prospective this system can be easily integrated in an existing wireless network, achieving the goal of providing a wireless data access system augmented with indoor localization, maintaining the same communication layers. This latter characteristic allows the WSN system architect designers to easily implement also smart routing network protocols, such as the one presented in [7].  
The mesh area influences the localization accuracy significantly, demonstrating a clear trade-off between in-mesh and out-mesh results. The experimental data in the specific scenario presented in this work demonstrate that larger mesh provides a significant trade-off between accuracy and system complexity.  
Provided that the aforementioned system is meant to allow an easy to integrate and non-invasive localization platform, the anchor mesh positions should be easily selected through an a priori process  
Figure 14: Measured localization error distribution over space for each mesh configuration (white area coincides with inaccessible room space, see Figure 9b), (**a**) large mesh; (**b**) medium mesh; (**c**) tiny mesh.  
Figure 13: Simulated localization error distribution over room area for each mesh configuration: (**a**) large mesh; (**b**) medium mesh; (**c**) tiny mesh.  
that does not require complex steps of either calibration or testing. To help on this, the proposed simulation procedure has been validated by measurements results and thus can be used to forecast the optimal anchor network mesh area.  
Table 4 shows a comparison between the presented system and actual state-of-art to the knowledge of the authors. Note that the system under consideration in this work is the only one that does not require any kind of training or supplemental data sources, and despite this its localization accuracy results are comparable with the one achieved by other state-of-art systems, while maintaining a similar density of anchors. This feature result is very important, and enabling for the optimization of future indoor localization system deployment.  
**Author Contributions:** Conceptualization, M.P. and A.C.; methodology, M.P. and S.M.; software, M.P.; validation, M.L.; formal analysis, M.P. and A.C.; investigation, M.P. and A.C.; resources, A.C. and G.C.; data analysis, M.L.; writing--original draft preparation, M.P.; writing--review and editing, M.L. and G.C.; writing--final version A.C.; visualization, M.L.; supervision, A.C.; project administration, G.P.; funding acquisition, G.C. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by Regione Toscana POR CreO FESR 2014-2020--Action 1.1.5.a3--Bando FAR--FAS 2014, under the \"SUMA--Struttura Urbana Multifunzionale Attiva\" project.  
**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.