Analysis of wideband phased array beamforming at millimeter wave frequencies

Abstract. Industries are undergoing an information and communication technology-driven transformation as the world becomes increasingly digitally and globally linked. 5G technology provides a common basis for providing the multiple vertical sectors with a more cost-effective, open, and wide ecosystem solutions. Due to the generally large attainable bandwidths, high frequency technologies have emerged as a promising solution for future wireless communications and attracted great interest in the literature. The millimeter wave (mmWave), i.e., the frequency range 30–300 GHz, would enable the exploitation of tens of gigahertz transmission bands, resulting in a massive channel capacities of even over one Tbps. However, one of the most challenging issues in high-frequency communication connections is the significant channel losses that require highly directional antennas and, in most cases, line-of-sight link between the transmitter and receiver. In this thesis, we study the beamforming design for wideband systems with different bandwidths. The simulation results show that with a larger bandwidth, the power loss increases with the beamforming angle. The loss of power behavior due to beam squinting effect is quite similar over different distances

Low Power Analog Processing for Ultra-High-Speed Receivers with RF Correlation

Ultra-high-speed data communication receivers (Rxs) conventionally require analog digital converters (ADC)s with high sampling rates which have design challenges in terms of adequate resolution and power. This leads to ultra-high-speed Rxs utilising expensive and bulky high-speed oscilloscopes which are extremely inefficient for demodulation, in terms of power and size. Designing energy-efficient mixed-signal and baseband units for ultra-high-speed Rxs requires a paradigm approach detailed in this paper that circumvents the use of power-hungry ADCs by employing low-power analog processing. The low-power analog Rx employs direct-demodulation with RF correlation using low-power comparators. The Rx is able to support multiple modulations with highest modulation of 16-QAM reported so far for direct-demodulation with RF correlation. Simulations using Matlab, Simulink R2020a® indicate sufficient symbol-error rate (SER) performance at a symbol rate of 8 GS/s for the 71 GHz Urban Micro Cell and 140 GHz indoor channels. Power analysis undertaken with current analog, hybrid and digital beamforming approaches requiring ADCs indicates considerable power savings. This novel approach can be adopted for ultra-high-speed Rxs envisaged for beyond fifth generation (B5G)/sixth generation (6G)/ terahertz (THz) communication without the power-hungry ADCs, leading to low-power integrated design solutions

Impact of beam misalignment on THz wireless systems

Abstract This paper focuses on deriving expected values for the transmit (TX) and receive (RX) antenna gains in terahertz (THz) wireless fronthaul and backhaul links under stochastic beam misalignment, which is created by antenna movement coming from the building or antenna mast swaying. In particular, four different antenna movement models are considered: (i) Gaussian motion of a single antenna; (ii) Gaussian motion of both the TX and RX antennas; (iii) 2-dimensional (2D) Gaussian motion of a single antenna; and (iv) 2D Gaussian motion of the one antenna and one-dimensional Gaussian motion of the other. Models (i) and (iii) depict fronthaul scenarios, in which the access point is usually installed in high buildings or in road-sides. Models (ii) and (iv) may model backhaul applications. To verify the analysis and quantify the impact of beam misalignment, analytic and simulations results are provided that reveal that the antenna motion can cause a significant degradation on the expected value of the TX and RX antenna gains. Moreover, the derived models are used in a link budget assessment and insightful results for a number of realistic scenarios are given. These result clearly highlight the impact of beam misalignment in the received signal quality as well as the importance of taking into account the beam misalignment and using the correct antenna movement model, when evaluating its impact