Is the cyclic prefix necessary?
  We show that one can do away with the cyclic prefix (CP) for SC-FDE and OFDM at the cost of a moderate increase in the complexity of a DFT-based receiver. Such an approach effectively deals with the decrease in the number of channel uses due to the introduction of the CP. It is shown that the SINR for SC-FDE remains the same asymptotically with the proposed receiver without CP as that of the conventional receiver with CP. The results are shown for $N_t$ transmit antennas and $N_r$ receive antennas where $N_r \geq N_t$. 
Naresh Sharma and Ashok Armen Tikku