Backscatter-assisted non-orthogonal multiple access for ultra-massive machine-type communications in 6G networks

6G cellular networks will require to provide significantly higher system capacity and user data rates. This potential growth along with today's shortage of spectrum increases the need for new frequency spectrum. The new millimeter wave spectrum is emerging as a suitable candidate with a large amount of available bandwidth (around 60 GHz). The new spectrum places a new requirement for single element antenna and array design. This work addresses the issues of mm-wave antenna design and the problems that designer may face during the designing process. The proposed antenna has a resonating frequency of 26 GHz and 2 GHz bandwidth. Beam squint problem is also analysis in this work. The results showed that the gain of the mm-wave antenna array becomes a function of frequency which significantly reduces the performance of mm-wave communication system. Millimeter wave (mmWave) wireless technology has become a part of human life for high-speed and secure data transmission. A square microstrip patch antenna with a resonance frequency of 26GHz was proposed in this work for mmWave wireless communication. One square radiating element makes up the antenna. CST Microwave Studio, an electromagnetic simulation program, was used to construct and study the suggested antenna on a Rogers RO 3003 lossy substrate with a relative permittivity of 3. This work's outcome demonstrates a minimal return loss of -19.34 dB, a gain of 6.97 dBi, and a bandwidth of 2GHz at a resonant frequency of 26 GHz. The element is transformed into an 8-element uniform linear array; the suggested array boosts the gain to 16dBi while maintaining a high radiation efficiency. A high-gain wide-band planar antenna with a reconfigurable intelligent surface (RIS) is presented in this study for use in contemporary wireless communication applications. The antenna is composed of two primary components: a basic antenna component with two light-dependent resistor switches and cross-line slots, and a second component that uses the RIS layer for beam steering. The RIS is made up of two-sided, five-by-five-unit cells that form a square. The antenna substrate is a 1.6 mm thick dielectric layer of FR4 epoxy glass. In order to attain the appropriate electromagnetic properties at the frequency band of interest, the RIS inclusions are developed and numerically tested. The manufactured prototype achieves an antenna gain ranging from 10.5dBi to 16.8dBi and exhibits a wide band covering frequencies from 0.9GHz to 3.5GHz with S11 below -10dB. Effective aperture utilization is demonstrated by experimental measurements in all shapes, and beam steering from +22° to -22° is achieved without lowering side-lobe levels. To assess channel performance in terms of bit error rate (BER) and channel capacity (CC), the suggested antenna's performance is compared to actual measurements. In contrast to traditional RIS-assisted antennae that depend on PIN or varactor switches, the presented work conducted LDR-controlled design offers compact beam steering with little insertion loss.