applied sciences  
IQM Mitigation Algorithm with Channel Awareness for  
Upstream SC-FDMA Systems in the Context of  
Dual-Hop Broadcasts  
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Footnote 14: email: https://transmissions used in the downstream and upstream situations, respectively, of fourth-generation cellular networks [11; 12].  
While OFDMA shares the available bandwidth among subcarriers, SC-FDMA assigns the available bandwidth to a single subcarrier. When mapping data to the parallel subcarriers in OFDMA, envelope fluctuation happens, which leads to a high peak-to-average-power ratio (PAPR). SC-FDMA has a reduced PAPR in upstream communications, which facilitates the construction of cost effective amplifiers and increases the transmit power efficiency of mobile terminals, hence extending battery life. Such advantages make SC-FDMA more desirable in wireless communications systems. Therefore, it is adopted in the long-term evolution of upstream wireless standards. It is also adopted in new 5G communication networks such as machine-to-machine communications and green communications [13; 14].  
The dual-hop approach is an additional essential method for improving the performance and reliability of communications systems without the need to deploy numerous antennas, which raise the device's price, power utilization, and size [15; 16; 17]. By using neighboring nodes, the broadcast signal can be replicated and sent to the recipient through several, potentially unreliable, fading pathways. Hence, we are able to achieve spatial diversity, which boosts the efficiency of the system. It is also crucial in scenarios when the receiver is beyond the range of the transmitter. with the assistance of dual-hop communications, the range of a signal can be increased without resorting to excessive power. Due of these benefits, dual-hop communications have been adopted for usage in a wide variety of wireless contexts, including but not limited to mobile communications, wireless sensor networks, the internet of things, and microwave and satellite communications [18; 19; 20]. Amplify-and-forward (AF) and decode-and-forward (DF) are the most prevalent techniques employed by a relay to accomplish dual-hop communications. The complexity of the system is increased by DF since it conducts demodulation and decoding, while the AF method merely amplifies and transmits the signal [21].  
Multicarrier and dual-hop communications are susceptible to radio frequency deficiencies such as in-phase (I) and quadrature-phase (Q) mismatch (IQM) [22]. Simply, the IQM is any departure from the condition in which the sine and cosine chains have a 90\({}^{\circ}\) phase shift and equal amplitudes. In the analog domain, where low cost manufacturing processes are often used, perfect IQ matching is not feasible. This mismatch is becoming increasingly common as the complementary metal-oxide semiconductor (CMOS) technology becomes more extensively used owing to their lower cost and simplicity of incorporation with digital baseband processing [23; 24]. In addition, as carrier frequencies rise, the IQM will become more severe and difficult to eradicate. Mismatches created in the analog domain may be remedied by the development of effective procedures in the digital domain. It is important to keep in mind that these discrepancies are not consistent from chip to chip and are thus impossible to forecast.