Experimental analysis and simulative validation of dynamic spectrum access for coexistence of 4G and future 5G systems

5G mobile networks will very likely include features that allow for a dynamic spectrum access (DSA) in order to exploit spectrum holes of a primary system. The efficient utilization of spectrum holes with minimum impairment of the primary system requires a waveform with a very low adjacent channel leakage ratio as well as robustness to time and frequency offsets. One of the approaches for new waveforms is Generalized Frequency Division Multiplexing (GFDM), a digital multi-carrier transceiver concept that employs pulse shaping filters to provide control over the transmitted signal´s spectral properties. In this paper we present experimental results that evaluate the impact of the new GFDM waveform on an existing 4G system. The 4G system was based on Eurecom´s OpenAirInterface for the eNB and a commercial UE. The 5G system was emulated using the LabVIEW/PXI platform with corresponding RF adapter modules from National Instruments and TUD´s GFDM implementation. The experimental results show that GFDM can be used with about 5 dB higher transmit power than a corresponding orthogonal frequency division multiplexing (OFDM) system, before any impact on the primary system is noticeable. The results from our real-time measurements were validated by simulations.