Wireless and mobile communications have been enjoyed by widespread popularity because of their access ﬂexibility and ability for providing high data rate trafﬁc with adequate decoding quality. Its Ensued by the increasing demand of wireless data service, in which the current cellular system cannot yet satisfy a required densiﬁcation of the network. Consequently,maintaining data trafﬁc on mobile networks grows exponentially at a sufﬁcient rate due to the increase of users. The current technical challenges are how to design future mobile radio networks to be more energy efﬁcient and to accommodate the extra trafﬁc while the quality of service. In this paper, we are introducing VFDM as recently proposed technique for spectrum sharing as candiate to manage spectrum in new generation mobile communication technology. The main goal is to study fundamental problem of how two tiers share the transmit band, to capitalize on the available spectrum and avoid possible inefﬁciencies. We analyze the coexistence of the two tiers for interference management through spectrum sharing in time duplex mode. VFDM enables the transmitting system of secondary network (system) to optimize the transmission rates of the two tiers by making decisions on the resource occupation jointly in the frequency domains. Two cases are studied: single user and Multi user system. A precoder constructed based on vandermonde matrix generated by the roots of the z-transform of the channel response was designed to eliminate/cancel the interference for both systems. In case of multi user, a linear cascaded precoder generates zero interference on the primary network and manages multi-user interference in the secondary network. We compare simulation result for both cases based on the performance. In addition, based on the design of cross-tier precoder in case of both non-cooperation and cooperation within smallcell user equipment, we will see that the cooperative XTP (Cross-tier precoder) can increase signiﬁcantly.