CRS precoding weights for wide beam coverage in FD-MIMO antenna arrays

Full Dimension MIMO (FD-MIMO) systems employ 2D antenna arrays with many elements, and are capable of user selective 3D beamforming with very narrow beamwidth. However, certain signals such as the CRS (Common Reference Signal) signal, are not beamformed but broadcasted to the whole sector. We present a method to generate a 2D wide beam with beamwidth that covers a given 2D sector (elevation and azimuth) and all antenna array elements excited at full power. This is not a trivial task considering that, in general, if all antenna array elements are excited at full power (all precoding weights have amplitude 1) then a narrow antenna beam is generated.