Orthogonal frequency division multiplexing (OFDM) is a multicarrier transmission system that can achieve high data rate over wireless channels. At the same time, multiple input multiple output OFDM (MIMO-OFDM) in wireless communication systems has been exposed to offer significant improvement over wireless technology by providing transmit diversity. It has become a promising technique for high-performance 5G broadband wireless communications. However, the main problem associated with MIMO-OFDM is that its signal exhibits high peak-to-average power ratio (PAPR), which causes nonlinear distortion and consequently performance degradation. Besides, PAPR carries weaknesses such as an increase in power consumption of high power amplifier (HPA) and analog to digital converter (ADC). Thus, 5G base stations will push up power requirements because energy consumption grows with the number of transceiver elements. So, mobile operators must find the right compromise that, on the one hand, guarantees a certain level of performance to a data flow, and, on the other hand, the energy cost generated for the deployment of the network. For this, as part of the management of power consumption, we propose MIMO constant envelope OFDM (MIMO-CE-OFDM) technique. In this work, we used MIMO-CE-OFDM to mitigate the nonlinear effect of HPA and ADC. To perform practical simulations, we have used COST 2100 MIMO channel model. In this paper, a MIMO-CE-OFDM system has been presented and analyzed under COST 2100 channel model conditions. Simulation results are given to illustrate the performance of [Formula: see text] MIMO-CE-OFDM in the presence of both HPA and ADC nonlinearity. This work shows that the effect of nonlinearity is shown to be negligible on MIMO-CE-OFDM signal.

The choice of modulation and waveform is a crucial step for generating a radio signal and designing a wireless communication system. Toward this end, a compromise between low-complexity and high-data rate had to be considered when selecting the appropriate transmission technique. Indeed, pulse-based modulation can be a good candidate for THz system due to its simplicity and it supports very high data over short distance. In this work, we proposed a solution based on multiband on-off keying (MB-OOK) modulation using a noncoherent receiver. A deferential MB-OOK transceiver has been evaluated over a THz channel model. A data rate of 54.24 Gbps is achieved with a BER of 10-3 when the distance between transmitter and receiver less than 35 m. Furthermore, the proposed system offers a good compromise between throughput, consumption, and complexity, which allow it to be a good candidate for THz applications.

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