Feedback Design for Multi-User MIMO Systems

The authors consider feedback design for the integration of multi-user MIMO in cellular mobile radio systems. Feedback is given by the mobile terminals, which report beam indices referring to a set of fixed pre-coding beams and corresponding signal to Signal to Interference and Noise Ratio (SINR) for different supported spatial transmission modes. The SINR feedback is quantized with a different number of bits, and the performance in terms of throughput achieved with a score-based scheduler is evaluated. Test scenarios from multi-cell simulations as well as single-sector measurements are considered. Results show that cell-edge users benefit the most from an increased amount of feedback bits.