On the design of an FBMC based AIR interface enabling channel adaptive pulse shaping per sub-band

By application of pulse shaping, the FBMC (Filter Bank Multi Carrier) based offset-QAM-OFDM (OQAM-OFDM) modulation scheme offers a new degree of freedom in designing mobile communication systems. In this contribution we investigate the coexistence performance in terms of interference isolation of individually configured sub-bands, i.e. individual prototype filter functions (PFF) and/or subcarrier spacing per sub-band, in the context of multi-user or multi-service scenarios as envisaged for 5G. To that end, we analyze the synchronization requirements of different of PFF from literature suggested for OQAM-OFDM and determine the required amount of guard bands with respect to the applied PFFs and subcarrier spacing configurations. The simulation results prove that the required amount of guard bands for OQAM-OFDM systems is independent on the time offset between different users. As a rule of thumb we can state, that for a minimum co-user interference isolation of 20 dB a bandwidth of one subcarrier spacings of the user with the largest subcarrier spacing has to be used as in-band guard bands.