Interleaved Training and Training-Based Transmission Design for Hybrid Massive Antenna Downlink

In this paper, we study the beam-based training design jointly with the transmission design for the hybrid massive antenna single-user (SU) and multiple-user (MU) systems where outage probability is adopted as the performance measure. For SU systems, an interleaved training design is proposed where the feedback is concatenated with the training procedure to monitor the training status and to have the training length adaptive to the channel realization. Exact analytical expressions of average training length and outage probability are derived for the proposed interleaved training jointly with SU transmission. For MU systems, a joint beam-based interleaved training, beam assignment, and MU data transmission design is proposed. Two solutions for the beam assignment are provided with different complexity-performance tradeoff. Analytical results and simulations show that for both SU and MU systems, the proposed training and joint transmission designs achieve the same outage performance as the traditional full-training scheme but with significant saving in the training overhead.