Adjustable dynamic range for paper reduction schemes in large-scale MIMO-OFDM systems

Adjustable dynamic range for paper reduction schemes in large-scale MIMO-OFDM systems

In a multi-input-multi-output (MIMO) communication system there is a necessity to limit the power that the output antenna amplifiers can deliver. Their signal is a
combination of many independent channels, so the demanded amplitude can peak to many times the average value. The orthogonal frequency division multiplexing
(OFDM) system causes high peak signals to occur because many subcarrier components are added by an inverse discrete Fourier transformation process at the base station. This causes out-of-band spectral regrowth. If simple clipping of the input signal is used, there will be in-band distortions in the transmitted signals and the bit error rate will increase substantially.

This work presents a novel technique that reduces the peak-to-average power ratio (PAPR). It is a combination of two main stages, a variable clipping level and an
Adaptive Optimizer that takes advantage of the channel state information sent from all users in the cell.

Simulation results show that the proposed method achieves a better overall system performance than that of conventional peak reduction systems in terms of the symbol
error rate. As a result, the linear output of the power amplifiers can be minimized with a great saving in cost.