MIMO adaptive codebook for cross-polarized antenna arrays

In this paper we address the design of MIMO double codebook structure for cross-polarized antenna arrays. Double codebooks consist of two codebook components, a wide-band long-term component and a short-term sub-band component. Herein we study particularly the two layer short-term sub-band component and provide the complete set of structure types leading to orthogonal constant modulus codewords and cross-polarization phase of M-PSK alphabet. By 3GPP LTE system simulations we show that a novel, two layer structure type, provides significant improvements in channels with large angular spreads.