Closed-form BER expression derivation for sequential OFDM system

Abstract Sequential Orthogonal Frequency Division Multiplexing (SeqOFDM) is a modulation scheme riding on OFDM and shown to provide a better spectral efficiency without introducing undesirable degradation in the Bit Error Rate (BER). In the scheme, a mapper is added at the input of an OFDM transmitter. This mapper is a lookup table that helps select three carriers for every four bits (or symbols) presented. These carriers form the OFDM subcarriers for signal transmission. At the receiver output is a demapper that maps the received carriers to the table of the equivalent bits effectively doing the opposite of the mapper. This paper presents a theoretical analysis of the scheme, deriving closed-form expressions for BER over Additive White Gaussian Noise (AWGN) channel. Theoretical results are benchmarked against Monte Carlo simulations under identical configurations, with findings demonstrating a strong agreement between theoretical predictions and simulated outcomes, particularly in the mid-to-high Signal to Noise Ratio (SNR) regime, confirming the accuracy of the derived model. An extension of the derivation is made to Rician and Rayleigh channels, The results offer a reliable foundation for the design and optimization of SeqOFDM communication systems which at the same time circumvents the computationally intensive and time-consuming process of BER estimation through Monte Carlo methods. Thus, the objective of providing a fast and scalable alternative for performance evaluation is met.