Non-contiguous OFDM (NC-OFDM), is well suited to enable spectrum usage in such dynamic environments. NC-OFDM is similar to OFDM, except that the transmission is restricted to certain sub-carriers. Non-contiguous sub-carrier access may arise either due to the presence of Primary users, or due to the frequency selective nature of the channel, or to ensure fair allocation of spectrum. Enabling the use of NC-OFDM for dynamic spectrum access requires two key challenges to be addressed first. First, NC-OFDM requires an agreement between transmitter receiver about the set of subcarriers being used in that link (i.e. frequency synchronization), and second, timing and frequency offset estimation must be established to ensure successful data detection.
Here is the GNU radio implementation of NC-OFDM on Github
R. Kumbhkar, T. Kuber, G. Sridharan, B. Narayan, Mandayam and I. Seskar, “Opportunistic spectrum allocation for max-min rate in NC-OFDMA,” 2015 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN), Stockholm, Sweden, 2015, pp. 385-391, doi: 10.1109/DySPAN.2015.7343934.
R. Kumbhkar, G. Sridharan, N. B. Mandayam, I. Seskar and S. Kompella, “Impact of asynchronous transmissions in noncontiguous OFDMA,” 2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN), Piscataway, NJ, 2017, pp. 1-9, doi: 10.1109/DySPAN.2017.7920788.