Optimal Scattering Devices Location for Multi-User MIMO Beamforming

摘要

This paper investigates optimal locations for scattering devices in a multiple-input multiple-output (MIMO) channel using transmitter (Tx) beamforming techniques. It aims to find best locations of the active scatters in a MIMO system so that the radiated power at a desired receiver antenna element is maximized while total radiated power is minimized. The Tx beamforming for multiple orthogonal beams (OB) uses beam shaping techniques under multiple specified performance constraints; not only to control radiated power density peak at a desired receiving (Rx) element at a specified level, say 0 dBm/m^{2, but also to suppress radiated power density levels to below -40dBm/m2 at other undesired receive (Rx) antenna elements. A line-of-sight (LOS) channel model is developed, and optimized active scatter locations are selected for MIMO systems. Composite transfer functions (CTF) based on channel state information (CSI) are built with CVX optimization in beam-shaping in the Tx array with multiple elements. It is demonstrated by selecting the location of scatters, not only the radiated power at a desired receiver antenna element is maximized while total radiated power is minimized, but also multiple OB beams are generated with active scatters for frequency reuse by multiple users.}