Investigation of Techniques for Reducing Mobile Communication Systems Harmful Out-Of-Band Emission

Electromagnetic compatibility in the newly designated Long-Term Evolution (LTE) mobile network in the 790–862 MHz frequency band from perspective of interference management between neighbouring services are analysed in the dissertation. Main focal point of this dissertation is on the problems that face LTE networks based on Orthogonal Frequency-Division Multiplexing (OFDM) due to the relatively strong side lobes around the active subcarriers in the main communication channel, which introduces interference effects between LTE stations and other services. The introductory chapter presents the investigated problem, objects of research, importance of the dissertation, describes research methodology, scientific novelty and the defended statements. The situation in the 790–862 MHz frequency band is overviewed regarding most sensitive challenges in the first chapter: LTE stations’ influence on Short-Range Devices (SRD), digital terrestrial TV broadcasting (DVB-T) and aeronautical radio navigation systems (ARNS). The noticeable lack of information is observed regarding SRD and LTE electromagnetic compatibility. The Filter Bank Multicarrier Transmission technique (FBMC) is pro-posed as means to minimize adjacent band interference in the 790–862 MHz frequency band. Main FBMC benefits are presented through comparison with reference case of OFDM. The key advantage of FBMC technique is derived from its low out-of-band leakage, which guarantees minimum harmful interference level between stations using adjacent channels. The harmful interference of LTE mobile stations’ influence on Short-Range Devices operating in the 863–870 MHz frequency band is analysed in the second chapter. Two analysis methods are used in this study: first applying theoretical analysis using Minimum Coupling Loss calculations, then statistical Monte-Carlo in order to verify results obtained in theoretical approach. The third chapter is focused on the experimental analysis to reproduce the situation that was investigated in theoretical analysis chapter. Verification of theoretical analysis by practical measurements confirmed that the LTE user equipment (UE) emissions may affect SRD devices and completely or partially disrupt their communications at distances of up to several meters from LTE UE. The obtained results are summarized and general conclusions are drawn