Modification to DFT -Based Codevectors for Beamforming over the SCM Using Circular Arrays

For enhancement of the received signal quality and spectral efficiency, transmission techniques using multiple antennas are becoming more important. To achieve the expected performance of multi-antenna transmission, efficient beamforming by applying appropriately designed codebooks is desired. Although eNBs (or base stations) are evolving to include antenna arrays of various sizes and shapes, most codebooks proposed earlier are targeted for uniform linear arrays (ULAs). We present a codebook construction scheme for circularly shaped arrays, using parameters which are adjusted to flexibly set the initial phase and step size values based on the location of user equipment (UE). The amount of gain achieved by the proposed codebook over the conventional ones is quantified using the spatial channel model (SCM) adopted by 3GPP.