Prof. Dr.-Ing. Werner Henkel
The combination of multicarrier modulation (OFDM, DMT) and Multiple- Input Multiple-Output (MIMO) transmission significantly improves the quality and efficiency of modern communication systems. The peak-toaverage ratio problem in multicarrier modulation requires additional transmitter side processing which may get considerably complex in the case of MIMO transmission. This problem is particularly emphasised in MIMO broadcast scenarios (MIMO BC), where the necessary precoding block at the transmitter side severely aspects the complexity of the PAR reduction algorithms. Many of the most important PAR reduction schemes that have been developed for SISO (Single-Input Single-Output) and MIMO systems, become too complex and inadequate for practical implementations when precoding is performed at the transmitter. Herein, on the one hand, we will refer to Selected Mapping (SLM) and Selected Sorting (SLS) PAR reduction schemes, explained in (4), which operate by generating multiple signal representations in the frequency domain. On the other hand we will analyze the performance of the Tone Reservation Method (TR), originally proposed by Jose Tellado in (1). We show that the tone reservation method, which operates entirely in time domain, significantly improves the PAR in MIMO scenarios as well, while retaining low complexity.
[Thesis] PAR Reduction in MIMO Broadcast OFDM Systems using Tone Reservation