Simplification of Transmit Resource Control in E-SDM with Adaptive Modulation

Eigenbeam space division multiplexing systems in a multiple-input multiple-output channel require resource adaptation (a modulation scheme and transmit power allocation for each stream) optimized based on criteria such as throughput maximization. We propose a technique to simplify transmit resource control for the purpose of implementing the algorithm on an actual system. The proposed technique uses simple calculations with eigenvalues derived from the channel information and noise power of a receiver to achieve the most appropriate transmit resource control. By contrast, the conventional technique requires complex calculations of throughput for all possible combinations of modulation schemes. Additionally, our technique can accommodate any number of antenna elements. The results of computer simulation show that the performance of the proposed technique is almost the same as conventional performance throughout the signal-to-noise ratio (SNR) region, although the simplification is analytically valid only for high SNR