Line-of-Sight 2Ă—nr MIMO With Random Antenna Orientations
Abstract: sight (LoS) multiple-input multiple multiple-output output (MIMO) gives full spatial spatialLine-of-sight multiplexing gain when the antenna array geometry and orientation are designed based on the interterminal distance. These known design methodologies that hold for antenna arrays with fixed orientation do not provide full MIMO gains for arbitrary array orientations. In this paper, we study LoS MIMO channels with random array orientations when the number of tra transmit nsmit antennas used for signaling is 2. We study the impact of common array geometries on error probability, and identify the code design parameter that describes the high signal signalto-noise noise ratio (SNR) error performance of an arbitrary coding scheme. For planar pla receive arrays, the error rate is shown to decay only as fast as that of a rank 1 channel, and no better than SNR-3 for a class of coding schemes that includes spatial multiplexing. We then show that for the tetrahedral receive array, which uses the smallest allest number of antennas among nonplanar arrays, the error rate decays faster than that of rank 1 channels and is exponential in SNR for every coding scheme. Finally, we design a LoS MIMO system that guarantees a good error performance for all transmit/re transmit/receive ceive array orientations and over a range of interterminal distances.