Comparative Analysis of Triangular QAM vs Square QAM Based OFDM Systems

Abstract

Traditional orthogonal frequency division multiplexing (OFDM) systems use square quadrature amplitude modulation (SQAM) as a preferred modulation scheme for data transmission. The advantages of signal-to-noise transmission rate, by employing higher modulation schemes with low detection complexity. However, the power consumption for data transmission is high which imposes a constraint on Square QAM in OFDM systems. Towards this end, the triangular quadrature amplitude modulation (TQAM) scheme is an efficient approach in this regard. It provides comparable performance to SQAM mapping concerning transmission rate and low complexity detection. Nevertheless, the advantage of using TQAM over the SQAM scheme is its less power consumption during data transmission due to its compact signal points in the constellation mapping. In this work, we propose the use of the TQAM scheme in OFDM systems and compare its performance to the traditional SQAM scheme. We model the TQAM-based OFDM system and analyze its parameters such as bit error rate (BER) and symbol error rate (SER). Moreover, we present the 16 points and 64 points mapping in the TQAMbased OFDM system for the peak to average power reduction (PAPR) and mean power minimization using trellis shaping (TS). Our simulation results show that the TQAM scheme achieved a notable performance gain with less power consumption. For 16-ary and 64-ary TQAM mapping, we achieved a gain of 0.46 dB and 0.55 dB, respectively, in terms of BER. Additionally, the TQAM-based OFDM system is analyzed by using Trellis Shaping (TS) technique for peak-to-average power (PAPR) ratio and mean power reduction. The proposed TQAM mapping provides a significant reduction in both PAPR and mean power reduction as compared to the traditional SQAM. Furthermore, a comparative analysis of SQAM and SQAM-based OFDM systems, through several constellation strategies, is carried out in terms of BER, SER, PAPR reduction, and mean power reduction which justifies the practical application of TQAM-based OFDM systems. The BER of the proposed system is evaluated over an additive white Gaussian noise (AWGN) channel with hard decision decoding using the syndrome former which affirms the efficacy of the proposed strategies.