Omnidirectional Precoding for Massive MIMO With Uniform Rectangular Array—Part I: Complementary Codes-Based Schemes

In the public channels, it is desirable to transmit the common signals omnidirectionally to ensure cell-wide coverage. In Part I of this two-part paper, we develop low-cost closed-form omnidirectional precoding designs for a massive multiple-input multiple-output (MIMO) system equipped with a uniform rectangular array (URA). By formulating the omnidirectional transmission design for a general URA as a feasibility optimization problem, we derive...