Space-time block codes (STBC) versus beam pattern scanning (BPS): capacity, performance, complexity and spectrum efficiency evaluation

In this paper, two transmit diversity techniques, space-time block coding (STBC) and beam pattern scanning (BPS) (also called beam pattern oscillation) are compared. Beam pattern scanning was recently introduced in the literature, where controlled time varying phase shifts are applied to the antenna array elements mounted at the base station. This creates a small movement in the antenna array pattern directed toward the desired user. In a rich scattering environment, this beam pattern movement creates an artificial time varying channel which generates time diversity exploitable at the receiver. The BPS scheme enhances receiver performance via diversity and network capacity via directionality. In this work, we conduct a comparison between STBC and BPS schemes in terms of their complexity and antenna physical dimension, network capacity (in term of number of users), bit-error-rate (BER) performance, and their relative spectrum efficiency. Network capacity (considering inter-cell-interference effects) and BER performance simulations are generated and compared. We see that BPS achieves a higher network capacity and BER performance with a smaller antenna dimension and complexity (especially for wideband systems) with minimal cost of spectrum efficiency. This identifies BPS technique as a promising scheme for future wireless communications.