# Design and Analysis on Decoupling Techniques for MIMO Wireless Systems in 5G Applications
## 6 Conclusions and Discussion
These methods used for MIMO as a tool to solve for current characteristic modes and desired isolated radiation patterns can be calculated fast. In addition, some decoupling researches are also combined with algorithm optimization, which is also worthy of reference in the search for the optimal solutions of decoupling, such as MIMO isolation performance improvement based on genetic algorithm [75], optimization of ground length based on particle swarm algorithm (PSA) [76], optimization of antenna parameters and synthesizing beam patterns based on hybrid gravitational search algorithm and PSA [77]. Adopting these objective methods, the time consumed for decoupling optimization work can be substantially reduced compared to traditional operations. In the future, realizing the goal of automation and high efficiency during the decoupling optimization procedure is also the potential work for us. It can be well defined that the development target of the MIMO decoupling issue: to achieve the highest isolation possible within a compact physical space. Although the experimental results of the above decoupling methods are satisfactory, the decision of decoupling schemes should be judged according to the features of MIMO systems and the transmission environment of the signal in reality. The realization of MIMO decouplingis not only an art of electronic design, but also a never-ending pursuit of high system performance of the current antenna field, and many possibilities and potentials are waiting to be explored. We hope that the analysis and discussion of MIMO decoupling techniques in this paper will inspire new thinking and look forward to more innovative and insightful approaches emerging in future 5G applications. [PERSON], [PERSON] and [PERSON] contributed to conceptualization, articulation, original draft preparation, review and the editing of the document. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analysis or interpretation of data; in the writing of the manuscript or in the decision to publish the results. +++ ==WARNING: Truncated because of repetitions==
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* [PERSON] et al. (2010) [PERSON]; [PERSON]; [PERSON] Radiation Pattern Calculation for Arbitrary Conformal Arrays that Include mutual-coupling effects. _IEEE Antennas Propag. Mag._**2010**, _52_, 57-63. [CrossRef]
* [PERSON] and [PERSON] (1988) [PERSON]; [PERSON] Direction Finding in The Presence of Mutual Coupling. In Proceedings of the Twenty-Second Asilomar Conference on Signals, Systems and Computers, Pacific Grove, CA, USA, 31 October-2 November 1988. [CrossRef]
* [PERSON] and [PERSON] (2015) [PERSON]; [PERSON] Direction-of-Arrival Estimation: Measurement using compact antenna arrays under the influence of mutual coupling. _IEEE Antennas Propag. Mag._**2015**, _57_, 62-68. [CrossRef]
* [PERSON] et al. (2009) [PERSON]; [PERSON]; [PERSON]; [PERSON] DOA Estimation for Uniform Linear Array with Mutual Coupling. _IEEE Trans. Aerospace Electron. Syst._**2009**, _45_, 280-288. [CrossRef]
* [PERSON] (2002) [PERSON] Effect of element mutual coupling on the capacity of fixed length linear arrays. _IEEE Antennas Wirel. Propag. Lett._**2002**, \(1\), 157-160. [CrossRef]
* [PERSON] and [PERSON] (2006) [PERSON]; [PERSON] Effect of Mutual Coupling on Capacity of MIMO Wireless Channels in High SNR Scenario. _Prog. Electromagn. Res._**2006**, _65_, 27-40. [CrossRef]
* [PERSON] et al. (2007) [PERSON]; [PERSON]; [PERSON] Effect of Signal and Noise Mutual Coupling on MIMO Channel Capacity. _Wirel. Pers. Commun._**2007**, _40_, 317-328. [CrossRef]
* [PERSON] et al. (2003) [PERSON]; [PERSON]; [PERSON] Exact representation of antenna system diversity performance from input parameter description. _Electron. Lett._**2003**, _39_, 705-707. [CrossRef]
* [PERSON] (2006) [PERSON]; [PERSON] Envelope correlation in (N,N) MIMO antenna array from scattering parameters. _Microw. Opt.