WLC01-1: Quantized-Feedback Optimal Adaptive Multi-Beam Forming for MIMO Systems

A novel approach to adaptive transmit multi-beam forming is developed for multiple-input multiple output (MIMO) systems. Since the method adapts the transmit beams by computing and quantizing the optimal direction of adaptation for each beam, we call it the quantized-feedback optimal adaptive multi-beam forming (QFOA-MUB) algorithm. The number of feedback bits for each beam is arbitrary: it can 1 bit, or as large as affordable. This algorithm allows transmission in orthogonal beam spaces, therefore substantially increasing the system capacity. Since the increment vector points in the direction that yields the largest directional derivative, the convergence speed is maximized. We show analytically that the algorithm has global convergence, irrespective of quantization error.