The upper mid-band – approximately from 7 to 24 GHz — has recently attracted considerable interest for new cellular services. This frequency range has vastly more spectrum than the highly congested bands below 7 GHz while offering more favorable propagation and coverage than the millimeter wave (mmWave) frequencies. In this regard, the upper mid-band has the potential to provide a powerful and complementary frequency range that balances coverage and capacity. Realizing cellular networks that exploit the full range of these bands, however, presents significant technical challenges. Most importantly, spectrum will likely need to be shared with incumbents including communication satellites, military RADAR, and radio astronomy. Also, the upper mid-band is simply a vast frequency range. Due to this wide bandwidth, combined with the directional nature of transmission and intermittent occupancy of incumbents, cellular systems will likely need to be agile to sense and intelligently use large spatial and frequency degrees of freedom. This paper attempts to provide an initial assessment of the feasibility and potential gains of such adaptive wideband cellular systems operating across the upper mid-band. The study includes: (1) a detailed ray tracing simulation to assess potential gains of multi-band systems in a representative dense urban environment and illustrate the value of a wideband system with dynamic frequency selectivity; (2) an evaluation of potential cross-interference between satellites and terrestrial cellular services and interference nulling to reduce that interference; and (3) design and evaluation of a compact multi-band antenna array structure. Leveraging these preliminary results, we identify potential future research directions to realize next-generation systems in these frequencies.

With the growing demand for spectrum utilization, the concept of full duplex transceivers has become attractive. These simultaneous transmit and receive systems (STAR) are attractive as they double bandwidth utilization. To realize STAR, we must suppress self-interference (SI) between transmit and receive antennas. Doing this across a wide bandwidth presents an even greater challenge. Further, for antenna arrays, SI can be higher due to mutual coupling among neighboring elements. In this paper, we achieve 100 dB isolation for practical STAR, across a large 500 MHz bandwidth. Specifically, four stages of the self-interference cancellation are proposed. In addition to high isolation cross-polarized array elements, we employ multi-tap filters at the transceiver RF front-end for interference cancellation. These filters emulate direct SI coupling using frequency-domain optimization techniques. Measured results show an average of 25 dB filter cancellation is possible across 500 MHz.

People's health is adversely affected by environmental changes and poor nutritional habits, emphasizing the importance of health awareness. The healthcare system encounters significant challenges, including data insufficiency, threats, errors, and delays. To address these issues and advance medical care, we propose a secure healthcare prediction method, prioritizing patient privacy and data transmission efficiency. The Quantum-inspired heuristic algorithm combined with Kril Herd Optimization (QKHO) is introduced for healthcare prediction, along with a comparison to the Deep Forward Neural Network (DFNN) optimized using Krill Herd Optimization (KHO) and Quantum-inspired heuristic algorithm combined with Kril Herd Optimization. The proposed QKHO model outperforms conventional models and exhibits higher accuracy, precision, recall, and F1-score. Blockchain technology ensures secure data transmission to the server, surpassing the security level of existing RSA and Diffie-Hellman algorithms.

Digital beamformers combined with ultrawideband (UWB) antennas are essential for realizing cognitive and software defined radios. Concurrently, advances in digital technology and signal processing have drastically reduced digital beamforming complexity. Recently, a novel on-site coding receiver (OSCR) architecture was proposed to significantly reduce hardware requirement for digital beamforming. Using OSCR, the signal from each antenna element is encoded, then several of these signals are grouped and digitized using a single analog-to-digital converter. Doing so, hardware requirements are drastically reduced. At the digital back-end, field programmable gate arrays are used to decorrelate and recover the signals associated with each array element for beamforming. In this paper, we demonstrate the effectiveness of the OSCR concept by building and testing a multichannel receiver using commercialoff-the-shelf components. Various test bench measurements are performed in an anechoic chamber using an UWB antenna array operating from 200 MHz-2.5 GHz, and data were collected at multiple frequencies. Results show an accurate estimate of the angle of arrival for incidence angles of θ _s = 0°, 15°, 30°, and 45° away from broadside. It is verified that on-site coding has minimal or no degradation in signal-to-noise ratio.

The development of reconfigurable antennas compatible with a CubeSat form factor can aid several space missions. Often, satellite missions require multiple wireless links with the same radio, but the design of such antennas is challenging due to the mechanical constraints and the limited power aboard a CubeSat. In this paper, we present a unique reconfigurable antenna concept enabled by adhesive polyimide tapes. The presented antenna can switch from a conventional patch to a monopole-like antenna with minimal actuation complexity. This reconfiguration provides choices for polarization, pattern, and gain without use of active components for size, cost and power consumption reductions. The frequency of operation is S-band (2.4 GHz), and the antenna achieves S11<-10 for both reconfiguration states. Measurements compare well with simulations in both states.