In 5G networks, mitigating blockage effects in millimeter-wave (mmWave) signals is a major challenge to overcome. Coordinated multipoint (CoMP) transmission is one of the inference mitigation schemes that can be used in a densified cellular network. CoMP transmission is usually implemented within a cloud radio access network (C-RAN) via fronthaul links which is connected to a control unit (CU). In this paper, a radio unit clustering scheme (RCS) was proposed based on CoMP transmission to mitigate blockage effect of mmWave links. Applying a clustering scheme in C-RAN can increase the network capacity by avoiding data transmission via non-line-of-sight (NLOS) links. Based on stochastic geometry, the coverage probability of the proposed RCS is derived into a closed-form expression by modeling the position of base stations as a Poisson point process. In addition, an enhanced cooperative handover scheme is proposed to increase mobility robustness of the proposed RCS. Simulation results show that the coverage probability is enhanced as the cluster size increases in mmWave C-RANs and a radio link failure (RLF) probability during handover procedure is reduced.