9. Integration of Heterogeneous Spectrum Sensing Devices Towards Accurate REM Construction

This chapter introduces a recently developed generic REM construction architecture capable of integrating heterogeneous spectrum sensing devices, combining the spectrum sensing and the database approach for accurate radio environmental mapping. It elaborates on the required interfaces and data structures, architectural components and toolboxes for spectrum data collection, storage, processing and usage. Different spectrum sensing devices possess diverse sensing, processing and hardware capabilities in terms of sensitivity, data resolution, gains, sweeping time, processing power, antennas etc. This yields various practical implementation challenges in order to facilitate their integration into a single REM construction platform. The practical challenges vary from code compatibility and processing limitations up to device calibration. This chapter places a particular focus on the device calibration procedure as a quintessential part of the integration process and discusses in details its theoretical and practical aspects. Furthermore, the book chapter elaborates on a prototype implementation based on the developed REM architecture and several types of spectrum sensing devices: USRP2, SunSPOTs and TI eZ430 RF2500. All heterogeneous devices are upgraded with custom developed software for interfacing to the REM prototype and providing versatile spectrum measurement capabilities based on different energy detection techniques. The performances of the developed prototype and the gains of using a larger scale heterogeneous measurement platform for REM constitution are validated in terms of Radio Interference Field (RIF) estimation via spatial interpolation, source localization, propagation model estimation and statistical analysis of spectrum occupancy. All presented evaluations, discussions and conclusions stem from the authors’ own practical work in the field.