Peak-to-Average Power Ratio Reduction in Multi-User OFDM

In this paper variants of selected mapping are investigated for different MIMO OFDM scenarios (point-to- point, multiple-access, and broadcast channel). Particular focus is on the broadcast scenario, where transmitter side precoding is mandatory which usually increases peak-to-average power ratio (PAR). The combination of (non-linear) precoding with a selected mapping technique leads to a very high computational complexity because it operates on all carriers. This paper introduces a new PAR reducing method which affects only a subset of carriers and therefore saves complexity. Because PAR reduction is achieved by optimizing the sorting in the precoding scheme, this technique is called selected sorting.