Iterative decoding of precoded multichannel system with PAPR reduction

In a multichannel system, the transmitter can perform precoding techniques to alleviate the effects of fading and interference. However, the precoding transformation matrix usually results in high peak to average power ratio (PAPR). In order to avoid inefficiently operating the power amplifier, for a precoded multi-input multi-output (MIMO) system, we consider using a PAPR reduction method based on integer reversible mapping which neither introduces redundancy nor requires any control signaling. However, without proper decoding methods that can produce soft output, the application of this PAPR reduction method to practical systems becomes limited because the channel decoding performance will be affected and iterative decoding of the precode and the channel code is not possible. In this paper, we investigate how to provide soft outputs for the decoding of the precode with PAPR reduction using a list sphere decoder. The simulation results show that list sphere decoding can provide effective soft output for the precode. They also imply that the precode with PAPR reduction, together with the outer channel code, can provide concatenation gain.