Experimental performance evaluation of a 5G spectrum sharing scenario based on field-measured channels Oriol Font-Bach ∗ , Nikolaos Bartzoudis ∗ , David L´ opez ∗ , Evgenii Vinogradov † , Miquel Payar´ o ∗ , Claude Oestges † ,Tor Andre Myrvoll ‡ , Vidar Ringset ‡ ∗ Centre Tecnol` ogic de Telecomunicacions de Catalunya (CTTC), Castelldefels, Barcelona, Spain Email: {oriol.font, nikolaos.bartzoudis, david.lopez, miquel.payaro}@cttc.cat † ICTEAM, Universit` e Catholique de Louvain, Louvain-la-Neuve, Belgium Email: {evgenii.vinogradov, claude.oestges}@uclouvain.be ‡ SINTEF ICT, Trondheim, Norway Email: {torandre.myrvoll, vidar.j.ringset}@sintef.no Abstract—In this paper, an experimental performance eval- uation is carried out within a communication scenario that features two of the key enablers of 5G: (i) the use of post-OFDM modulations and (ii) an efficient use of the spectrum via spectrum sharing. The experimental lab set-up has been assembled so as to operate in conditions as realistic as possible via the actual real- time implementation of the involved transceivers and also via the utilization of propagation channels which have been recorded in a field measurement campaign and which are loaded in a channel emulator that also operates in real-time. The experimental results show that co-existence in a shared spectrum scenario is possible and that the performance degradation is kept at a low level as long as one of the two users is making use of spectrally agile post- OFDM modulations such as filterbank multicarrier (FBMC). I. I NTRODUCTION While fourth generation (4G) wireless network deployments are still underway, a joint effort involving the entire industry and academic community is making steady progress towards the definition and specification of 5G systems, providing as well early proof-of-concepts and prototypes of key technol- ogy enablers. This paper focuses on two specific technology enablers of 5G wireless communication systems: (i) filter bank multi-carrier (FBMC) is a spectrally efficient waveform that is currently proposed to complement or enhance the current 4G long term evolution (LTE) technology [1]. Among other candi- date waveforms, FBMC is being evaluated in the framework of different European Commission (EC) funded research projects focusing on 5G topics [2] [3]. (ii) Operators foresee that the efficient exploitation of the existing underutilized licensed spectrum is a means to sustain the anticipated increased traffic demands when 5G systems will start being deployed after 2020. Although the use of spectrum above 6 GHz for 5G radio access systems is gaining momentum, the Next Generation Mobile Networks (NGMN) Alliance clearly underlines that a flexibly utilized frequency spectrum below 6 GHz is absolutely essential for a cost-efficient delivery of mobile services in current and future 5G systems [1]. These two 5G technology enablers were combined in a FBMC downlink (DL) communication system that largely adopted the LTE specifications and frame structure, demon- strating promising results in terms of spectral efficiency and spectral contention (i.e., without compromising the perfor- mance of other adjacent or in-band transmissions [4]). In principle, the premium characteristics of FBMC in terms of spectral efficiency and interference protection to adjacent transmissions can be applied to a plethora of 5G end-use scenarios, where underutilized fragmented spectrum exists (licensed, unlicensed or a combination of the two). In this paper we present an experimental analysis of the gains achieved when FBMC waveforms are used as secondary transmissions having as a goal to exploit the unused spec- trum of other licensed narrowband primary transmissions. The assembled testbed allowed the performance evaluation of (a) a configurable DL FBMC system able to optimally utilize fragmented spectrum in a band where narrowband primary transmissions take place and (b) a point-to-point standalone DL FBMC system. Field-measured channels that were recorded employing a channel sounder in different indoor and outdoor configuration setups have been also used to increase the practical interest of the experimental analysis. The remaining of the paper is organized as follows. The targeted 5G operating scenario is defined in Section II. In Sec- tion III, the channel measurement campaign is described. The broadband FBMC system is defined in Section IV. Likewise, the utilized hardware setup is described in Section V. The experimental analysis is presented in Section VI. II. TARGET 5G SCENARIO The NGMN Alliance defines as a key 5G operating pre- requisite the use of new flexible waveforms to effectively exploit underutilized licensed and unlicensed spectrum below 6 GHz [1]. Optimal spectral contention of the fragmented spectrum is required for these new waveforms in order to ensure a non-interfering coexistence with other signals (either in-band or at the edges of adjacent bands). Due to the high 2015 IEEE 26th International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC): Fundamentals and PHY 978-1-4673-6782-0/15/$31.00 ©2015 IEEE 958