Noisy Beam Alignment Techniques for Reciprocal MIMO Channels

摘要: Future multi-input multi-output (MIMO) wireless communications systems will use beamforming as a first-step towards realizing the capacity requirements necessitated by exponential increase in data demands. The focus of this work is on beam alignment for time-division duplexing (TDD) systems, which we propose number novel algorithms. These algorithms seek to obtain good estimates optimal beamformer/combiner pair (which are dominant singular vectors channel matrix). They motivated power method, an iterative algorithm determine eigenvalues and eigenvectors through repeated matrix multiplication. In contrast basic method considers only most recent iteration assumes noiseless links, proposed techniques consider information from all previous iterations combine them different ways. first technique ( Sequential Least-Squares ) sequentially constructs least-squares estimate matrix, then used calculate estimate. second Summed Power aims mitigate effect noise using linear combination previously tried beams next beam, providing improved performance low-SNR regime (typical mmWave systems) with minimal complexity/feedback overhead. A third Initialized combines at high-SNR low-complexity advantage priming summed initial sequential method.