Efficient, reliable, and secure millimeter-wave transmitter systems for joint communication and sensing
Author(s)
Mannem, Naga Sasikanth
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Abstract
Phased array systems have gained attention in the recent years targeting mmWave frequencies to overcome the path loss by improving the EIRP on the TX side and SNR on the receiver side. Although phased arrays improve the communication range of mm-wave systems by improving the antenna gain, they exhibit several limitations such as scan angle dependent antenna impedance variations (antenna voltage standing wave ratio (VSWR)), limited security, narrow beamwidth etc. In this dissertation, I present several circuit/system innovations to address these limitations and enhance the performance of mm-wave and antenna array-based communication/sensing systems.
CHAPTER 2 introduces a silicon-based antenna VSWR resilient linear power amplifier (PA). The proposed PA supports reconfigurable modes of operation with a 2-way power combining PA supporting both series and parallel Doherty PA operations. Moreover, the amplitude and phase can be reconfigured to improve the PA’s performance under antenna load variations. Furthermore, switching between the series and parallel Doherty PA operations, superior performance is maintained over both halves of the smith chart thus supporting antenna loads over full VSWR circle.
CHAPTER 3 presents a multi-band role-exchange parallel Doherty-like power amplifier using a coupled line-based output network. The proposed output network covers the 26-60GHz bandwidth by switching the roles of main and auxiliary amplifiers in a 2-way Doherty PA depending on the frequency of operation, thus supporting active load modulation over the entire operational bandwidth.
CHAPTER 4 presents schemes to achieve directionally secure communication links using MIMO TX array. The proposed schemes include constellation decomposition array (CDA) and spatial carrier aggregation array (SCA). CDA spatially combines lower order modulated signals such as QPSK, 16QAM into a higher order modulated signal such as 64QAM using antenna array. The desired RX in broadside receives a perfect 64QAM signal due to in-phase combination, while the undesired RXs receive distorted constellations of 64QAM thus producing a secure communication link towards target RX. SCA does temporal swapping of carriers (different modulated signals) among a 2-element TX array to create a secure communication link towards target RX.
CHAPTER 5 presents a new array architecture called Frequency Modulated Arrays (FMA) TX for full FoV localization of receivers/targets. This scheme employs a variable frequency offset between antenna elements in an array to produce distinct temporal waveforms towards RXs located in different spatial directions. The received distinct waveform is used to determine the RX location with respect to the TX array. This similar scheme is also be used to perform sharp angular localization of targets in radar mode.
CHAPTER 6 presents a silicon-based PTA (phase-time array) TX providing directional security and Rx localization, hence support for joint communication and sensing systems. This PTA scheme uses a complementary combination of phase shift and time delay between antenna elements in an array, thus creating spatial dispersion effect when a wideband input signal is presented to it. This spatial dispersion effect causes different frequency contents to be focused in different directions. Thus, the incoming frequency content at a RX is used to determine its angular location with respect to the PTA TX. Furthermore, this scheme is also extended to create directionally secure communication links with reconfigurable security.
These proposed techniques can enable wideband, efficient, reliable, and secure links targeting several applications including 5G/ beyond 5G communication, radar, vehicular communication, wireless backhaul etc.
CHAPTER 7 provides a conclusion to the dissertation.
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Date
2022-09-22
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Text
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Dissertation