Abstract
Owing to the rapid growth in wireless data traffic, millimeter-wave (mm-wave) communications have shown tremendous promise and are considered an attractive technique in fifth-generation (5G) wireless communication systems. However, to design robust communication systems, it is important to understand the channel dynamics with respect to space and time at these frequencies. Millimeter-wave signals are highly susceptible to blocking, and they have communication limitations owing to their poor signal attenuation compared with microwave signals. Therefore, by employing highly directional antennas, co-channel interference to or from other systems can be alleviated using line-of-sight (LOS) propagation. Because of the ability to shape, switch, or scan the propagating beam, phased arrays play an important role in advanced wireless communication systems. Beam-switching, beam-scanning, and multibeam arrays can be realized at mm-wave frequencies using analog or digital system architectures. This review article presents state-of-the-art phased arrays for mm-wave mobile terminals (MSs) and base stations (BSs), with an emphasis on beamforming arrays. We also discuss challenges and strategies used to address unfavorable path loss and blockage issues related to mm-wave applications, which sets future directions.
Highlights
Of the many fundamental inventions whose histories have been well documented, the origin of the antenna array is not generally known
Mm-wave technology is being considered overall for future 5G wireless communication systems, there remains the need for improvement and changes in current mm-wave architectures and the expected commercial designs to be used in mm-wave cellular communication networks [4,6,9]
To address the polarization mismatch [7,46] and incurred losses owing to the mobility of the user and various kinds of motions experienced by the mobile terminals at different angles, multi-polarized, i.e., horizontally polarized and vertically polarized antennas are combined in a subarray to achieve the diversity gain, while enhancing the efficiency of the transmission and reception at mm-wave frequencies [47]
Summary
Of the many fundamental inventions whose histories have been well documented, the origin of the antenna array is not generally known. An array of 20 antenna elements was designed for the experiment. Strong winds destroyed the designed array system; a two-element antenna array was used to successfully transmit a repeated Morse code signal letter “S” from Poldhu, UK to St. John’s in Canada. Another Nobel Prize-winning scientist, Luis Alvarez, was awarded the recognition globally for the discovery of the electronically scanning phased array. His innovation was initially triggered by the role of the U.S in World War II, and was the reason for the development of Eagle, which was the first reported radar-based bombing system. The use of phased arrays has been very common in the defense domain, and the design of warships and military jets focus on phased array radars
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