This paper presents the application of cyclic delay diversity (CDD) to block-based single carrier cyclic prefix (SC-CP) systems. It is shown that diversity advantage is achieved even without additional coding due to the inherent cross-tone pre-coding present in SC-CP. We also present a CDD SC-CP transmission system for correlated channels. By using beamforming techniques, virtual uncorrelated channels are created for CDD transmissions. Simulations results show that the proposed schemes provide diversity gain. Furthermore, when beamforming is used together with CDD, array gain is also observed