Efficient Techniques For in-band System Information Broadcast in Multi-Cell Massive Mimo

Abstract

In this paper we consider joint beamforming of data to scheduled terminals (STs) and broadcast of system information (SI) to idle terminals (ITs) on the same time-frequency resource in multi-cell multi-user massive MIMO systems. We propose two different multi-cell approaches to the broadcast of SI, i) synchronous broadcast of same SI symbols from all cells (SAME-SI), and ii) synchronous broadcast of statistically independent SI symbols from each cell (DIFF-SI). We also consider the traditional orthogonal access (OA) approach where a fraction of physical resource is reserved for broadcast of SI. Through analysis and simulations, it is observed that for both SAME-SI and DIFF-SI, joint beamforming and broadcasting (JBB) is more energy efficient than OA.