Searching for Spectrum Efficiency Paulraj As the mobile internet evolves from 4G today (e.g., WIMAX) to 6G by 2020, the expectations are that mobile link speeds will need to reach Gigabits/sec. Merely throwing bandwidth at this problem is not a solution. In part, there are no large chunks of mobile wireless spectrum (i.e., below 3.5 GHz), and also the links will remain Tx power limited, because of human safety factors. Therefore, spectrum efficiency will have to increase dramatically, perhaps reaching 10-12 bps/Hz/cell. This talk will discuss what tools might be available to meet spectrum efficiency goals.