# A Critical Examination of the Beam-Squinting Effect in Broadband Mobile Communication: Review Paper
## 5 Conclusions  
In this paper, a literature review has been introduced to analyse the relative issues of the squint phenomena of mmwaves in antenna arrays for modern communication systems. It is found that such problems become very effective at high-frequency bands due to the dispersion effects of antenna arrays in terms of angle of arrival and gain variation, which directly effect the channel performance. For this purpose, the authors classified the main effective solutions to resolve such problems, which include beamforming, antenna geometry, and channel estimation algorithms. Another classification can be considered that exploits the beam squint to take advantages from squint phenomena to enhance the channel localization and capacity through splitting the beam to different directions. In spite of these classifications, beamforming, for example, based on digital processes, realizes an excellent solution to minimize the effect of beam squint on bit error rate and channel capacity, however; it consumes high complexity with excessive cost. The relative algorithm based on channel estimation could be considered the next revolutionary approach, whereby the system consumes less hardware complexity and cost. However, it is very limited when the channel environment becomes highly dynamic, which consumes high delay in the data processing. For this reason, it becomes unreliable with increasing traffic and \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Ref.** & **Year** & **Method** & **Results** & **Remarks** \\ \hline
[54] & 2019 & Shift-invariant block-sparsity-based compression sensing (CS) algorithm & Provided more accurate channel estimation than other conventional methods & - \\ \hline
[55] & 2020 & Tansec waveform with nonlinear frequency modulation to account for carrier frequency variation & Beam direction error was reduced & Implemented in digital domain which increase complexity \\ \hline
[56] & 2021 & Algorithm for channel estimation using the greatest likelihood criterion in relation to the analog training beam and pilot error & The proposed algorithm minimized the mean square error & - \\ \hline
[57] & 2021 & For RIS-aided wideband (mmwave) communications, phase shift design approaches are used to reduce the impact of beam squint in both LoS and NLoS scenarios & Beam squint in such systems was effectively reduced by the proposed phase shift architecture & - \\ \hline
[59] & 2021 & Virtual subarrays and TDD lines & Effective in removing beam squint & Increasing hardware complexity \\ \hline
[60] & 2021 & Advanced analog beamforming method proposed based on the Zadoff-Chu (ZC) sequence & The performance loss caused by the beam squint can be efficiently reduced using the suggested strategy & - \\ \hline
[61] & 2021 & Three-dimensional electromagnetic analysis software & Clarify how beam squint occurred in RF lens antenna and compare its effect with phased array antenna & - \\ \hline
[63] & 2022 & Transceiver design based on lens antenna subarray (LAS) and analog sub band filters & Results showed performance enhancement & Higher frequencies require high quality filters which increase hardware complexity \\ \hline
[65] & 2020 & Create multi-user communication plans that make use of squinting multi-beam properties and small multi-wideband antenna arrays & Effective method to exploit beam squint with multi-user systems & Squint-beam-based compact multi-wideband array for millimeter-wave communications \\ \hline
[67] & 2022 & Control the beam squint using time delays and using it for localization & Effective method to exploit beam squint in localization & - \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._signal attenuation. The third classification is assumed to be a solution method; however, it is not. It is indeed a suggestion to avoid the negative effects of such phenomena by splitting the beam of the antenna array to support channel localization and create multiuser communication channels.