Enabling User Relaying In MCM-NOMA Under Doubly Selective Channels Using Iterative Interference Cancellation Schemes For Wireless IoT Networks

<div>Cell-edge users of the future cellular internet of things (IoT) with massive IoT sensors can suffer from extremely severe channel conditions, especially under very high-speed scenarios. In this paper, we present a performance improvement method for cell-edge users of multi-carrier modulation (MCM)-based non-orthogonal multiple access (NOMA) downlink systems. To this end, we consider the implementation of cooperative user relaying NOMA (CUR-NOMA) and derive its lower bound end-to-end bit error rate (E2E-BER) under doubly selective channels. In addition, the imperfect successive interference cancellation (SIC) process is analyzed, wherein two interference cancellation schemes are combined to remove the NOMA induced inter-user interference (IUI) and the doubly selective channel induced inter-carrier interference (ICI). Furthermore, numerical simulations are performed to prove the efficiency of the introduced schemes with imperfect channel state information (CSI) when compared to the theoretical perfect SIC with a perfect CSI case. </div>

Enabling User Relaying In MCM-NOMA Under Doubly Selective Channels Using Iterative Interference Cancellation Schemes For Wireless IoT Networks

<div>Cell-edge users of the future cellular internet of things (IoT) with massive IoT sensors can suffer from extremely severe channel conditions, especially under very high-speed scenarios. In this paper, we present a performance improvement method for cell-edge users of multi-carrier modulation (MCM)-based non-orthogonal multiple access (NOMA) downlink systems. To this end, we consider the implementation of cooperative user relaying NOMA (CUR-NOMA) and derive its lower bound end-to-end bit error rate (E2E-BER) under doubly selective channels. In addition, the imperfect successive interference cancellation (SIC) process is analyzed, wherein two interference cancellation schemes are combined to remove the NOMA induced inter-user interference (IUI) and the doubly selective channel induced inter-carrier interference (ICI). Furthermore, numerical simulations are performed to prove the efficiency of the introduced schemes with imperfect channel state information (CSI) when compared to the theoretical perfect SIC with a perfect CSI case. </div>

Partial Fractional Fourier Transform (PFrFT)-MIMO-OFDM for Known Underwater Acoustic Communication Channels

Communication over doubly selective channels (both time and frequency selective) suffers from significant intercarrier interference (ICI). This problem is severe in underwater acoustic communications. In this paper, a novel partial fractional (PFrFT)-MIMO-OFDM system is proposed and implemented to further mitigate ICI. A new iterative band minimum mean square error (BMMSE) weight combining based on LDLH factorization is used in a scenario of perfect knowledge of channel information. The proposed method is extended from SISO-OFDM configuration to MIMO-OFDM. Simulation results demonstrate that the proposed PFrFT-LDLH outperforms the other methods in the SISO-OFDM scenario and that its performance can be improved in MIMO-OFDM scenarios.

CLIPPING TECHNIQUES FOR PAPR REDUCTION IN FBMC/OQAM SYSTEM OVER DOUBLY-SELECTIVE CHANNELS

One of the major disadvantages of Filter Bank Multicarrier (FBMC) is high Peak-to-Average Power Ratio (PAPR) of transmitted signal. As a result, nonlinear power amplifier (PA) properties, considerable out-of-band and the in-band distortion types take place in the case where the signals of high peak exceed the PA saturation level. In the present study, a new method of the PAPR reduction is presented and applied to reduce PAPR in FBMC/OQAM system. Different clipping methods have been proposed and studied that are Amplitude Clipping (AC), Palm Clipping (PC), Deep Clipping (DC), and smooth Clipping (SC) for the reduction of PAPR. To evaluate and analyze the performance of PAPR reduction methods, PAPR and Bit Error Rate (BER) measures are used and programmed using MATLAB program. The simulation results show that the clipping methods are strong substitute methods which may be assumed as a method of PAPR reduction for the FBMC-based communication systems and AC appears to be the best method.