Mutual coupling in MIMO systems

The drive towards greater efficiency in communications systems has led to the birth of many new technologies and considerable improvements in existing systems over the last 20 years. These developments have been underpinned by increasing demands for higher data speeds, capacity and reliability by end users on a global level. Wireless communications systems have witnessed rapid transformations with this regard. Numerous enhancements in data capacities have been the hallmark of these systems. One of the principal components in achieving improved performance in wireless systems is the antenna system. Single Input Single Output (SISO) antenna topologies have traditionally been employed in wireless links. As the demand for higher data rates have persisted various limitations have arisen. Multiple Input Multiple Output (MIMO) antenna topologies have provided promise of the desired system capacity and reliability. Since MIMO systems employ two or more antenna pairs simultaneously, the effects of mutual coupling become a significant consideration in the quest to achieve high system performance. Therefore a clear understanding of mutual coupling effects with varying conditions in necessary for practical purposes. A lot of work has already been done on this subject. This thesis shall seek to substantiate some fundamental evidence on the relationship between mutual coupling effects and antenna element separation. The procedure shall involve the use of proven computer aided design software to achieve this purpose. Microstrip antennas (used interchangeably with patch antennas), widely known for their efficacy in wireless communications applications will be used for the tests. Specifically the more common linearly polarized rectangular microstrip antenna shall be utilised

Mutual coupling in MIMO systems

The drive towards greater efficiency in communications systems has led to the birth of many new technologies and considerable improvements in existing systems over the last 20 years. These developments have been underpinned by increasing demands for higher data speeds, capacity and reliability by end users on a global level. Wireless communications systems have witnessed rapid transformations with this regard. Numerous enhancements in data capacities have been the hallmark of these systems. One of the principal components in achieving improved performance in wireless systems is the antenna system. Single Input Single Output (SISO) antenna topologies have traditionally been employed in wireless links. As the demand for higher data rates have persisted various limitations have arisen. Multiple Input Multiple Output (MIMO) antenna topologies have provided promise of the desired system capacity and reliability. Since MIMO systems employ two or more antenna pairs simultaneously, the effects of mutual coupling become a significant consideration in the quest to achieve high system performance. Therefore a clear understanding of mutual coupling effects with varying conditions in necessary for practical purposes. A lot of work has already been done on this subject. This thesis shall seek to substantiate some fundamental evidence on the relationship between mutual coupling effects and antenna element separation. The procedure shall involve the use of proven computer aided design software to achieve this purpose. Microstrip antennas (used interchangeably with patch antennas), widely known for their efficacy in wireless communications applications will be used for the tests. Specifically the more common linearly polarized rectangular microstrip antenna shall be utilised

Massive MIMO is a Reality -- What is Next? Five Promising Research Directions for Antenna Arrays

Massive MIMO (multiple-input multiple-output) is no longer a "wild" or "promising" concept for future cellular networks - in 2018 it became a reality. Base stations (BSs) with 64 fully digital transceiver chains were commercially deployed in several countries, the key ingredients of Massive MIMO have made it into the 5G standard, the signal processing methods required to achieve unprecedented spectral efficiency have been developed, and the limitation due to pilot contamination has been resolved. Even the development of fully digital Massive MIMO arrays for mmWave frequencies - once viewed prohibitively complicated and costly - is well underway. In a few years, Massive MIMO with fully digital transceivers will be a mainstream feature at both sub-6 GHz and mmWave frequencies. In this paper, we explain how the first chapter of the Massive MIMO research saga has come to an end, while the story has just begun. The coming wide-scale deployment of BSs with massive antenna arrays opens the door to a brand new world where spatial processing capabilities are omnipresent. In addition to mobile broadband services, the antennas can be used for other communication applications, such as low-power machine-type or ultra-reliable communications, as well as non-communication applications such as radar, sensing and positioning. We outline five new Massive MIMO related research directions: Extremely large aperture arrays, Holographic Massive MIMO, Six-dimensional positioning, Large-scale MIMO radar, and Intelligent Massive MIMO.Comment: 20 pages, 9 figures, submitted to Digital Signal Processin

Agregados de antenas para sistemas massive MIMO 5G e satélite

Wireless telecommunications systems are growing and improving at a breakneck pace, and its demands must be ful lled with hardware modi cations. The fth-generation will demand a revolution since antennas are going to be designed for high frequency, millimeter wave bands, where there is a lot of unexploited spectrum worldwide. However, these frequencies get absorbed quite easily, for example, they su er high attenuation due to rain. This implies a decrease of radiated power. To solve some of the issues, antenna arrays have been studied due to their high versatility. This dissertation has the goal of designing and testing several solutions based on microstrip patch antennas. Initially, an analysis of the coupling between elements is performed as well as some proposed techniques to reduce it, through more compact spaces, without any gain decreasing. Finally, considering the space limitations, series antenna arrays are developed for satellite communications and presented an indepth study of antennas effciently employed for both transmission and reception simultaneously.Os sistemas de telecomunicações sem fios continuam a crescer e a melhorar a um ritmo frenetico, por isso, novos requisitos tem de ser cumpridos com modificações ao nível do hardware. A quinta geração exigirá uma revolução, uma vez que as antenas serão projetadas para alta frequência, banda de ondas milimétricas, onde o espetro ainda não foi muito explorado. No entanto, estas frequências são absorvidas com facilidade como, por exemplo, na atmosfera devido á atenuação originada pela chuva. Para resolver estas limitações, os agregados de antenas têm sido estudados devido á sua versatilidade. Esta dissertação tem o objetivo de desenhar e testar várias soluções baseadas em antenas microstrip (patch). Inicialmente, é realizada uma avaliação do acoplamento entre elementos e propostas algumas técnicas de redução do mesmo, utilizando espaços mais compactos que o usual, mas prevenindo quaisquer diminuições de ganho. Por fim, tendo em vista a mesma limitação espacial, são desenvolvidos agregados de antenas em série direcionados para comunicações via satélite e apresentado um estudo detalhado de antenas para transmissão e recepção em simultâneo.Mestrado em Engenharia Eletrónica e Telecomunicaçõe