The combined beamforming and space-time block coding technique for downlink transmission

To meet the increasing demand of large capacity and high quality for future mobile communications, techniques which can efficiently combine the beamforming technique and the space-time block coding (STBC) technique have been put forward to obtain beamforming gain as well as full diversity gain. In this paper, we propose two downlink transmission schemes which based on afore mentioned combining technique. In scheme I, an M-element single array structure is adopted. While in scheme II, a two sub-array diversity structure, each with M/2 elements, is employed. Simulation results show that with the same number of transmit antenna elements, both proposed schemes outperform the traditional beamforming or the STBC technique. Meanwhile, the bit error ratio (BER) performance of scheme II is superior to that of scheme I. Stable performance can be better achieved using scheme II, regardless of the signal direction of arrival (DOA) and the angle spread (AS).