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With the rapid advancement of wireless communication technologies, efficient utilization of the spectrum has become more complex and competitive. Millimeter-waveand Terahertz are considered to be one of the key technologies for next-generation wireless communication systems. However, high-frequency LOS links are sensitive to occlusions, which may lead to blocking problems during signal transmission. Therefore, in this study, we propose a recommendation system based on the knowledge graph of adaptive smart radio environment, which aims to solve the blocking problem that is prone to occur in the new generation of communication. The system utilizes deep learning and knowledge graph techniques, as well as sensing and understanding of the radio environment, to provide users with personalized communication services. First, it obtains information about the user's location, network state, and surroundings by sensing and understanding the wireless environment, second, it constructs a knowledge graph using the sensed information, and then, it extracts effective feature representations from the knowledge graph, including the user's communication history, device type, and network congestion, using deep learning techniques. Based on these features, the system generates personalized recommendations, such as optimizing the allocation of communication resources or selecting the best communication policy. By continuously learning and optimizing the wireless environment, the recommender system can provide more efficient and reliable communication services to solve the blocking problem in the new generation of wireless communications. [ABSTRACT FROM AUTHOR]

THz technology has the potential to revolutionize various fields, including high-speed wireless communication, medical imaging, and spectroscopy. One challenge facing THz technology, however, is the limited output power (on the order of microwatts) of photonic THz sources (e.g., uni-traveling-carrier photodiode). Researchers are therefore exploring THz beam steering techniques to maximize their power effectiveness. To this end, we propose a photonic THz beam steering method that utilizes fiber chromatic dispersion, eliminating the need for energy-consuming active electronics. This paper explains its basic operating principle, fabrication and performance analysis of the associated THz array antenna, and demonstrates the feasibility of achieving a 300 GHz beam steering within 10 ∘ by means of dispersion-varied polarization-maintaining fibers. In conclusion, the present scheme can greatly enhance the power efficiency of photonic THz sources, and enable the potential advantages of seamless integration with fiber-optic networks, including reduced complexity, simplified operation, low power consumption, and cost-effectiveness. [ABSTRACT FROM AUTHOR]

In this article, a beam steering millimeter-wave antenna array operating in ka-band frequency has been proposed for 5G applications. Thus, to achieve a beam switching and to ensure a low side lobe level (SLL), a 4 × 4 Butler matrix (BM) and a Chebyshev array are used respectively. Moreover, to minimize the antenna array dimensions, a multilayer structure is used, where the BM and the antenna array are printed on the bottom and the upper layers respectively. The two radio frequency structures are connected by using via connectors. Furthermore, to reduce the mutual coupling between the antenna elements, we have used a metamaterial surface (metasurface) composed by periodic complementary split ring resonators (CSRRs) printed on the back side of the top layer. As a result, enhancements of the radiation pattern in the E-plane and an impedance matching improvement have been achieved. In addition, a beam steering in the range of − 6° to + 27°, with a variation of the main lobe magnitude from 11.5 to 13.5 dB, and a multi-band behavior in the frequency range 25–40 GHz, have been achieved. [ABSTRACT FROM AUTHOR]

This paper introduces on-chip patch antenna with electronic beam switching using graphene strip array for wireless communications at 415 GHz. The on-chip patch antenna is printed on silicon/on-chip ground/silicon-oxide multilayer structure for simple integration with system electronic components. Groups of graphene strip arrays are placed parallel to the arms of polygon patch antenna fed by microstrip line connected to its base arm. When the group of N-graphene strips is biased by 15 V, it behaves as conductor strips which act as directors in Yagi-Uda antenna. The radiated beam is directed along with the biased group of graphene strips. When the graphene strips are unbiased 0 V, it behaves as dielectric strips and un-affect the beam direction. An equilateral triangular on-chip patch loaded with two groups of graphene strips is investigated. The effect of a number of graphene strips and their separation gap on the matching bandwidth and beam directivity is studied. It produces impedance bandwidth of 44% with maximum gain of 8.4 dBi and high radiation efficiency of 74%. A single directive beam is electronically switched in directions φ = 45° or φ = 135° by alternate biasing ON the two groups. Dual beams in both directions are achieved when the two groups are biased ON at the same time. A pentagonal-shaped patch loaded with four groups of graphene strips is studied. The single beam is switched in four different directions 0, 45°, 135°, and 180° based on the biased group. Dual, triple, and quad directive beams are radiated from the pentagonal patch with high gain of 7.85 dBi according to the number of biased groups. [ABSTRACT FROM AUTHOR]

The present paper deals with device-to-device (D2D) communication for millimeter wave and its performance in indoor wireless communication application. The 61 GHz Industrial Scientific and Medical band is considered for verification of link visibility and path loss behaviour. Line-of-sight (LOS) blockage is the major problem in indoor wireless communication as the signal gets attenuated when the LOS path comes across any obstacle. To overcome this problem, directional antennas are used through which the direction of propagation can be diverted. While selecting such non-line-of-sight (NLOS) path, the transmission path must offer relatively lesser attenuation. The output of this work would be useful for identification of NLOS paths by using beam switching mechanism for D2D communication. [ABSTRACT FROM AUTHOR]

PMAS, the Potsdam Multi-Aperture Spectrophotometer, is a new integral field spectrograph in the optical, which is optimized for good transmission and high image quality from 350 nm to 1 μm. We present our plan to implement a CCD charge-shuffle mode to allow for beam switching with a very high degree of sky subtraction accuracy for faint object 3-D spectroscopy. [ABSTRACT FROM AUTHOR]