Joint Spatial and Temporal PAR Reduction in MIMO OFDM

Multicarrier systems suffer from the high peak-to-average power ratio (PAR) of their transmit signal. In order to overcome this issue, peak-power reduction schemes have been developed. One of the most popular technique is selected mapping (SLM). Recently, a variant of SLM for single-antenna systems was proposed. This scheme considers temporally consecutive OFDM frames to achieve a further gain in PAR reduction. In this paper, this idea is extended to multi-antenna (MIMO) systems. Thereby, MIMO point-to-point scenarios as well as MIMO broadcast channels are assessed. For MIMO point-to-point scenarios, a joint spatial and temporal variant of directed SLM is introduced. As directed SLM cannot be applied over the antennas in broadcast scenarios, the combination is done with spatially simplified SLM. Numerical as well as analytical results of both approaches are given. A suited combination of complexity (introduced by SLM) and delay (introduced by constituting hyper frames) can be selected.