A Power Boosting Factor Determination for the Impulse Sample in Impulse Postfix OFDM Systems

Recently, a new Impulse Postfix OFDM (IP-OFDM) system, which performs channel estimation in time-domain by exploiting the impulse postfix instead of pilot tones, was proposed [1]. The proposed IP-OFDM system exploits the impulse postfix, which consists of a high power impulse sample and several zero samples at the end of a OFDM symbol block, to estimate channel impulse response. As shown in [1], [2], the IP-OFDM system can achieve the enhanced bit error rate performance compared to that of conventional OFDM systems, but there is an important Peak-to-Average Power Ratio (PAPR) issue for deciding the amount of impulse power in the IP-OFDM system. In [2], a statistic-based method was proposed to determine the amount of impulse power for avoiding the PAPR increase. However, the proposed method does not give meaningful intuition for us how the designed impulse power would affect to the performance of practical IP-OFDM systems. In real systems, there is a nonlinear High Power Amplifier (HPA) that may cause significant performance degradation of IP-OFDM by distorting the impulse postfix. Therefore, we propose decision criteria of the power boosting factor for impulse sample in practical IP-OFDM systems. With the proposed decision criteria, the impulse power is designed based on the characteristics of the nonlinear HPA. Simulation results demonstrate the effectiveness of the proposed decision criteria for IP-OFDM systems.