DM-RS Based Open-Loop CoMP in LTE-A System

Coordinated multi-point transmission/reception (CoMP) has been identified as an important way of mitigating interference and improving spectral efficiency for cell edge users in LTE-A system. However, current CoMP studies mainly focus on joint transmission (JT), dynamic point selection (DPS) and coordinated scheduling/beamforming (CS/CB) which all fall into closed-loop category. When considering medium or high mobility users, closed-loop CoMP seems less effective, while open-loop CoMP is more preferred, which is similar to that observed between closed-loop and open-loop single user multiple-input multiple-output (SU-MIMO). In this paper, we propose open-loop CoMP transmission frameworks for both spatial multiplexing and transmit diversity. We design our open-loop CoMP schemes by reusing long term evolution (LTE) open-loop SU-MIMO structures as much as possible to alleviate standardization efforts, and especially consider support for demodulation reference signals (DM-RS) which will be prevalent in future LTE-Advanced systems. Simulation results verify the effectiveness of our proposed open-loop CoMP schemes.