Although the research and development for the 6G wireless communication technologies were started and discussed widely, a particular waveform has yet to be selected as a strong candidate. Describing the technological prerequisites essential to enable \(\:5G/6G\) applications, the orthogonal chirp division multiplexing (OCDM) system is introduced for possible use in the PHY layer of the 6G communication systems. Compared with the conventional waveforms, the OCDM system is a more effective candidate for next-generation cellular schemes, especially for the sub-THz band applications. This is anticipated to cause significant harm to the waveform orthogonality of conventional systems, along with increased propagation loss on the information signals due to a high peak-to-average power ratio (PAPR) and inter-carrier interference (ICI). The primary objective of this manuscript is to design a system that is efficient in terms of power consumption and spectrum utilization. The chosen system should provide high throughput, minimize out-of-band (OOB) power emissions, and maintain the PAPR. In this paper, to achieve a sufficiently acceptable reduction in PAPR and OOB power emissions, we propose a new multiple-input multiple-output (MIMO) approach called discrete Fourier transform (DFT)-Spread windowing and restructuring (WR)-OCDM (MIMO DFT-Spread WR-OCDM) by targeting the upcoming communication systems. The suggested method effectively reduces PAPR and OOB power emissions by combining windowing and DFT-spreading approaches. Additionally, the frequency domain equalizer i.e., minimum mean square error (MMSE) is employed to mitigate the effects of inter-symbol interference (ISI). Comparison with the existing multicarrier systems based on the same simulation data indicates that this technique reduces the PAPR by \(\:0.40\:dB\) , but the OOB power emission is about \(\:2\:dB\) difference. Furthermore, we analyze the bit error rate (BER) performance in the time-invariant MIMO-multipath fading channels, revealing a significant improvement of signal-to-noise ratio (SNR) of approximately \(\:3.1\:dB\) over the suggested system. Overall, the simulation findings verified that our proposed system’s channel capacity is superior to the traditional multi-carrier systems by \(\:2\:bits/s/Hz\) .
