## 5 Conclusions  
WuRx and asynchronous communication offer significant energy savings for wireless sensor networks compared to synchronized communication protocols. Various approaches are possible to enhance the performance of WuRx, including the use of RF and LF amplifiers to increase the range of sensor nodes. As RF amplifiers, LNAs achieve sensitivities of up to \(-90\,\mathrm{dBm}\) and a data rate of several \(100\,\mathrm{kbit/s}\), but, on the other hand, higher latency, longer listening times, and higher power consumption. In order to achieve a sensitivity of more than \(-50\,\mathrm{dBm}\) within a power consumption lower than \(10\,\mathrm{\SIUnitSymbolMicro W}\), two LF amplifiers based on OA and BJT are introduced. However, the hardware of WuRx is still challenging in terms of compromise between sensitivity, data rate, latency, and low power consumption. In this work, two WuRx architectures based on LF amplifiers were investigated. In order to build a wireless sensor network for indoor localization and a multi-hop structure, the results were determined by analytical modeling, simulation, and experimental testing to compare the architectures in terms of influencing factors.  
The first architecture uses for the amplification stage a BJT architecture where the second one is based on OA. Results show that the BJT architecture can be placed at a distance of \(34\,\mathrm{m}\) with a reliability of the WuPt reception with a PER below \(10\%\), where the other architecture presents a distance of \(6\,\mathrm{m}\) with a PER below \(10\%\). When communicating between rooms through masonry, a high reception rate can be expected at a distance of more than \(10\,\mathrm{m}\), depending on the presence and, ultimately, the amount of furniture and objects in the rooms. Communication between several floors allows a secure wireless connection at a distance of up to \(12\,\mathrm{m}\). The paper shows that a wireless sensor network can be built with passive and discrete components such as Schottky diodes, BJT transistor, and OA with indoor ranges of more than \(30\,\mathrm{m}\), with a PER of less than \(10\%\). The limitation of the range in the rooms is mainly due to the furniture and interference with other radios such as transponder locks. The results show that LF amplifiers improve the sensitivity of the WuRx with low power requirement. However, when developing the hardware, it should be mentioned the trade-off between sensitivity, power consumption, and data rate.  
L.S. contributed by way of conceptualization, methodology, original draft writing, visualization, editing, and funding acquisition. R.F. contributed by way of writing of sections, reviewing, editing, and visualization. [PERSON], O.K. and F.D. contributed by way of writing of sections, reviewing, and editing. All authors have read and agreed to the published version of the manuscript.  
This research was funded by European Union Social Fund grant number K-7531.20/496-11 and financially supported by Leipzig University of Applied Sciences by funds of Sachsisches Staatsministerium fur Wissenschaft, Kultur und Tourismus.  
We acknowledge support by the Open Access Publication Funds of the Leipzig University of Applied Sciences.  
The authors declare no conflict of interest.