This study focuses on the design of a MATLAB platform for non-orthogonal multiple access (NOMA) based systems with link-level and system-level analyses. Among the different potential candidates for 5G, NOMA is gaining considerable attention owing to the many-fold increase in spectral efficiency as compared to orthogonal multiple access (OMA). In this study, a NOMA simulator is presented for two and more than two users in a single cell for link-level analysis; whereas, for system-level analysis, seven cells and 19 cells scenarios were considered. Long-term evolution (LTE) was used as the baseline for the NOMA simulator, while bit error rate (BER), throughput and spectral efficiency are used as performance metrics to analyze the simulator performance. Moreover, we demonstrated the application of the NOMA simulator for different simulation scenarios through examples. In addition, the performance of multi-carrier NOMA (MC-NOMA) was evaluated in the presence of AWGN, impulse noise, and intercell interference. To circumvent channel impairments, channel coding with linear precoding is suggested to improve the BER performance of the system.
The fourth Industrial Revolution is expected to lead to an era of technological innovation and digitization that would require connectivity by the users, anywhere and anytime. The fifth generation of wireless communication systems and the technologies therein are being explored to cater to high connectivity needs that encompass high data rates, very low latencies, energy-efficient systems, etc. A multiuser environment is anticipated that would require multiple access techniques, such as Nonorthogonal Multiple Access (NOMA). The user data in the power domain NOMA is superimposed, at the transmitter base station, which is in turn subjected to Successive Interference Cancellation at the user end. In the multiuser downlink, the desired user’s signal is subjected to imperfect SIC due to incomplete cancellation of the undesired user’s signal. Pulse-shaping of NOMA symbols using wavelet transform is proposed to mitigate the multiuser interference due to imperfect SIC. Closed-form symbol error rate (SER) expression is derived for the wavelet NOMA system for a three-user scenario. Analytical results show that wavelet transform pulse-shaped NOMA performs better compared to Fourier transform pulse-shaped NOMA symbols in mitigating SIC and thereby minimize the residual error due to imperfect SIC.
In this article, an ultra-wideband antenna has been presented for medical applications which have a resonant frequency of 10.35GHz and offers a bandwidth of 1400MHz with a return loss of -19db. The presented antenna is low-cost lightweight and can easily be integrated inside the circuit. As this antenna is designed for medical applications its size is compact and is fed utilizing a coaxial feeding technique which is especially plentiful for operative radiotherapy applications. The designed antenna is rectangular and covers an overall size of 24x12mm with a thickness of 1mm. The proposed antenna is designed using CST studio as a simulation tool, the extracted results of important parameters like return loss, surface current, reference impedance, and far-field have achieved remarkable results which are illustrated in the article. which makes it suitable for radiotherapy. A high epsilon valued ε r = 4.8, tan δ = 0.02 substrate GT-008 has been employed as a dielectric material whereas copper is being used for the ground and radiating patches. The performance of the antenna in the X-band is satisfactory which makes it suitable for radiotherapy.
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