RT Dissertation/Thesis
T1 Initial access and beam-steering mechanisms for mmWave wireless systems
A1 Palacios Beltrán, Joan
AB Future millimeter-wave networks will support very high densities of devices and accesspoints. This vastly increases the overhead required for access point selection and beamtraining. Due to unfavorable radio propagation, mmWave systems will exploit largescaleMIMO and adaptive antenna arrays at both the transmitter and receiver to realizesufficient link margin. Beamforming is vital to overcome the high attenuation in wirelessmillimeter-wave networks. It enables nodes to steer their antennas in the direction ofcommunication. Fortunately, the quasi-optical properties of millimeter-wave channelsmake location-based network optimization a highly promising technique to reduce controloverhead in such millimeter-wave WLANs.In this thesis we present tools to improve mmWave systems. We start by designingan effective lightweight sector beam-pattern design for using as a baseline for hybridanalog-digital structures. We deal with practical constraints of mmWave transceiversand propose a novel, geometric approach to synthesize multi-beamwidth beam patternsthat can be leveraged for simultaneous multi-direction scanning. Then we make use of thismulti-direction scanning to create a beam training protocol which effectively acceleratesthe link establishment by exploiting the ability of mobile users to simultaneously receivefrom multiple directions. We propose smart beam training and tracking strategies forfast mm-wave link establishment and maintenance under node mobility. We leverage theability of hybrid analog-digital transceivers to collect channel information from multiplespatial directions simultaneously and formulate a probabilistic optimization problem tomodel the temporal evolution of the mm-wave channel under mobility. We propose amechanism to extract full channel state information (CSI) regarding phase and magnitudefrom coarse signal strength readings on off-the-shelf IEEE 802.11ad devices. Using thisCSI, transmitters dynamically compute a transmit beam pattern that maximizes thesignal strength at the receiver. Channel properties and antenna design at 60GHz areideal for path angular information extraction, following an almost ideal geometric channelmodel. Due to this, we present some localization method specifically designed for the60GHz band. We merge the ideas presented in this thesis and by extracting channelstate information from off-the-shelf routers we estimate the user location to manage alocation aware beam-training and device handling method. The resulting scheme can predict blockage, optimize access point association, and select the most suitable antennabeam patterns while significantly reducing the beam training overhead.
YR 2020
FD 2020-07
LK https://hdl.handle.net/10016/31820
UL https://hdl.handle.net/10016/31820
LA eng
DS e-Archivo
RD 27 jul. 2024