Simple peak-to-average power ratio reduction by non-regular signal constellation sets

Peak-to-average power ratio (PAPR) is a major problem for high rate communication systems, which employ e.g. quadrature amplitude modulation (QAM) with a large signal constellation set (SCS). We propose a novel and extremely simple scheme for PAPR reduction, which removes the critical channel symbols from the SCS and instead map the respective bit patterns to other existing channels symbols. This results in non-unique bit mappings for non-regular SCSs. We demonstrate the PAPR reduction by examples which achieve reductions of close to 45% with almost no impact on the performance, which is proven by simulations. The performance is further analyzed and explained using a mutual information analysis.

I. Introduction

There is a high pressure to increase the data rates in today's wireless, wireline, and optical communication systems. One frequently used technique to increase the data rate in a communication system is to transmit more bits per channel symbol. This results in more possible channel symbols, which form the signal constellation set (SCS). One often used type of SCS is quadrature amplitude modulation (QAM), which puts the channel symbols on a regular orthogonal grid. For wireless systems such as HSDPA or LTE 64QAM is used, with 64 possible channel symbols and 6 bits per symbol. For wireline transmission e.g. by DVB-C even 4096QAM is specified, with 12 bits mapped to 4096 possible channel symbols.