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Limited research work has been conducted on deterministic modeling of the fifth-generation wireless communications within hospital patient rooms environment. This letter reports a ray-tracing model algorithm for the prediction of multiple-input–multiple-output (MIMO) propagation in the mm-wave band. The furniture effects are predicted in the framework of uniform theory of diffraction. Each piece of furniture is modeled as a group of perfect conducting wedges of random shape and size. The fixed access point has been configured with two forms of radiation patterns: Directional (D) and Omnidirectional (O). However, the mobile user point, remains O. Results indicate that doubling the number of antennas in a MIMO system operating under O-O configuration leads to a notable boost of 9 bps/Hz in channel capacity. The O-O setup creates a rich multipath environment, favorable for MIMO systems, resulting in an average channel capacity increase of 4 bps/Hz compared with the D-O configuration.

This article presents a compact self-quadruplexing antenna for scalp-implantable devices. The proposed self-quadruplexing antenna operates at 168 MHz [industrial, scientific, and medical (ISM) band], 433 MHz (ISM band), 915 MHz (ISM band), and 1400 MHz [wireless medical telemetry service (WMTS) band] when Ports 1, 2, 3, and 4 are activated, respectively. The proposed antenna is simulated inside a rectangular device in the head of a human phantom. The suggested antenna comprises four individually excited semicircular meandered resonators with a common ground plane. The compactness of the design is achieved using a high dielectric substrate and using semicircular meandered resonators. The meandered resonators enlarge the current path, resulting in significant miniaturization. As a result, the proposed antenna consumes a small volume of $12\,\, \times 14.5 \times 0.13 = 22.62$ mm3. The coupling among all ports is also minimized using an ultrathin substrate. Consequently, the mutual coupling between any two ports is less than −21.8 dB. It provides a peak gain of −36.24, −34.78, −31.39, and −30.10 dBi at 168, 433, 915, and 1400 MHz, respectively. The link budget and specific absorption rate (SAR) analyses are performed to see the possible applications in the head implant, which show promising results. The 10-g SAR values of 0.017, 0.016, 0.014, and 0.013 W/kg are realized at 168, 433, 915, and 1400 MHz, respectively. Based on a link margin (LM) ≥10 dB, the proposed self-quadruplexing antenna can communicate up to 20, 17.5, 12, and 9 m at 168, 433, 915 and 1400 MHz, respectively (at $B_{r} = 120$ Mbps). Furthermore, the simultaneous transmit and receive (STAR) ability of this antenna is validated using software-defined radios (SDRs). To the best of the authors’ knowledge, this is the first-ever self-quadruplexing implantable antenna designed so far.

Limited work has previously been conducted into deterministic modeling of the fifth generation (5G) millimeter (mm)-wave wireless communications within geometrically nonuniform tunnels. This study predicts and analyzes broadband multiple–input multiple–output (MIMO) propagation in underground mine tunnels for 5G communications and beyond. At extremely short wavelengths, each rugged and uneven surface of the tunnel is modeled as a group of diffracting rectangular prism wedges. A deterministic ray-tracing (RT) MIMO model is developed based on the Uniform Theory of Diffraction (UTD). All predicted MIMO subchannels have been successfully fitted with the experimental measurements. MIMO multipath fading of underground tunnels is found to be lognormally distributed and strongly depends on the tunnel’s size and shape.