RF beamforming in very wideband radio systems : analysis of the beam squint problem
Fè, Matteo (2020)
Fè, Matteo
2020
Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2020-12-22
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202012148827
https://urn.fi/URN:NBN:fi:tuni-202012148827
Tiivistelmä
In the last few years the wireless data traffic has been encountered an extremely fast growth with a consequent high demand for accessible radio spectrum. In particular, the fifth-generation (5G) wireless technologies require much more resources in order to be able to satisfy the requirements of high data rates, low latency and high-capacity.In order to satisfy all these requirements it is necessary to look forward new resources that were not utilized before, like the mmWave spectrum. The frequency bands characterized by wavelengths in the order of millimeters are usually referred to as mmWave frequencies. They include all the frequencies between 30GHz and 300GHz. These frequencies can be utilized in a very efficient way through techniques like beamforming, which will allow us to obtain the best effort from the new spectrum available. The main problem of the 5G generation is that the signal received from the arrays will result in the sum of many delayed components of the original signal which usually are approximated as phase shifts. Due to the very large bandwidth available in the mmWaves, it will not be possible to neglect anymore the delays and thus the phased-arrays will be characterized by a frequency dependency. This effect is referred to as beam squint.
In this work the effects caused by the beam squint are studied for the cases of uniform linear array (ULA), uniform planar array (UPA) and uniform circular array (UCA). The simulations show that the different array configurations are not affected in the same way by the beam squint problem due to their different characteristics. In particular, it has been shown that the linear geometry is the most affected by the beam squint. Finally, in order to study the impact on the transmission of a signal, it was performed a simulation of an OFDM transmission characterized by an analog beamforming architecture under the beam squint phenomenon. The results have confirmed that beam squint decreases the channel capacity, and therefore, it should be taken into consideration both for path selection and channel estimation.
In this work the effects caused by the beam squint are studied for the cases of uniform linear array (ULA), uniform planar array (UPA) and uniform circular array (UCA). The simulations show that the different array configurations are not affected in the same way by the beam squint problem due to their different characteristics. In particular, it has been shown that the linear geometry is the most affected by the beam squint. Finally, in order to study the impact on the transmission of a signal, it was performed a simulation of an OFDM transmission characterized by an analog beamforming architecture under the beam squint phenomenon. The results have confirmed that beam squint decreases the channel capacity, and therefore, it should be taken into consideration both for path selection and channel estimation.