  Two-port demodulation reference signals (DMRS) have been employed in new
radio (NR) recently. In this paper, we firstly propose a minimum mean square
error (MMSE) scheme with full priori knowledge (F-MMSE) to achieve the channel
estimation of two-port DMRS in NR. When the two ports are assigned to different
users, the full priori knowledge of two ports is not easy to be obtained for
one user. Then, we present a MMSE scheme with partial priori knowledge
(P-MMSE). Finally, numerical results show that the proposed schemes achieve
satisfactory channel estimation performance. Moreover, for both mean square
error and bit error ratio metrics, the proposed schemes can achieve better
performance compared with the classical discrete Fourier transform based
channel estimation. Particularly, P-MMSE scheme delivers almost the same
performance compared with F-MMSE scheme by a small amount of prior knowledge.
