High Capacity and High Coverage mm-Wave Multi-Antenna Systems
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The future generations of communication systems will require gigabit per second links. In order to provide the expected capacity, several possibilities have been investigated. One of them is the use of millimeter waves. Millimeter-wave (mmwave) technologies have been introduced in the market during the last years, and applications using such technology are expected to increase further in the near future. This represents an interesting solution due to the high available bandwidths and compact antenna dimensions. In this thesis, methods for obtaining high capacity mm-wave reliable links are studied. The designed systems involve the use of Multiple-Input-Multiple- Output (MIMO) and phased arrays, and give several advantages over most of the currently used single antenna systems. A number of aspects needs to be taken into account during a mm-wave link design. Due to the short wavelength of millimeter waves, the propagation losses are very high. Communications at these frequencies are mainly in line-of-sight. This means that coverage is an important aspect to be considered. In this thesis some of these issues are addressed. High capacity is achieved with the use of MIMO and a proper positioning of the transmitter and receiver elements, while antenna arrays are employed in order to provide the necessary gain and coverage. Specific systems have been designed for indoor and outdoor scenarios. A proper geometry is presented for the indoor case. The proposed system is able to achieve gigabit per second capacity as well as a wide angle of total coverage, which is obtained with the use of adaptive beamforming. For the outdoor case, since the attenuation is a critical issue for millimeter wave communications, we consider antenna arrays which can provide high gains. In addition MIMO multiplexing and proper antenna positioning are adopted to increase the capacity. Simulation results show that the system we design can achieve gigabit per second links for the range considered. Furthermore, we demonstrate that with the designed system robust links can be obtained, even in non-optimal weather conditions.