Due to its good orthogonality, slantlet transform (SLT) is used in orthogonal frequency division multiplexing (OFDM) systems to reduce intersymbol interference (ISI) and intercarrier interference (ICI). This eliminates the need for cyclic prefix (CP) and increases the spectral efficiency of the design. Finite Radon transform (FRAT) mapper has the ability to increase orthogonality of subcarriers, is nonsensitive to channel parameters variations, and has a small constellation energy compared with conventional fast-Fourier-transform- (FFT-) based OFDM. It is also able to work as a good interleaver, which significantly reduces the bit error rate (BER). In this paper both FRAT mapping technique and SLT modulator are implemented in a new design of an OFDM system. The new structure was tested and compared with conventional FFT-based OFDM, Radon transform-based OFDM, and SLT-based OFDM for additive white Gaussian noise (AWGN) channel, flat fading channel (FFC), and multipath selective fading channel (SFC). Simulation tests were generated for different channel parameters values. The obtained results showed that the proposed system has increased the spectral efficiency, reduced ISI and ICI, and improved BER performance compared with other systems. 1. Introduction Orthogonal frequency division multiplexing system is one of the most promising technologies for current and future wireless communications. It is a form of multicarrier modulation technologies where data bits are encoded to multiple subcarriers, while being sent simultaneously [1]. Each subcarrier in an OFDM system is modulated in amplitude and phase by the data bits. Modulation techniques typically used are binary phase shift keying, quadrature phase shift keying (QPSK), quadrature amplitude modulation (QAM), 16-QAM, 64-QAM, and so forth. The process of combining different subcarriers to form a composite time-domain signal is achieved using FFT and inverse FFT (IFFT) operations [2]. The main problem in the design of a communications system over a wireless link is to deal with multipath fading, which causes a significant degradation in terms of both the reliability of the link and the data rate [3]. Multipath fading channels have a severe effect on the performance of wireless communication systems even those systems that exhibit efficient bandwidth, like OFDM. There is always a need for developments in the realization of these systems as well as efficient channel estimation and equalization methods to enable these systems to reach their maximum performance [4]. The OFDM receiver structure allows
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