Interference Robust RF Beamforming Transceivers for mmWave and Beyond
Thesis event information
Date and time of the thesis defence
Topic of the dissertation
Interference Robust RF Beamforming Transceivers for mmWave and Beyond
Doctoral candidate
Master of Science (Tech) Muhammad Yasir Javed
Faculty and unit
University of Oulu Graduate School, Faculty of Information Technology and Electrical Engineering, Centre for Wireless Communications - Radio Tehnologies
Subject of study
Radio Engineering
Opponent
Assistant Professor Yanki Aslan, Delft University of Technology, The Netherlands
Custos
Professor Aarno Pärssinen, University of Oulu
Interference Robust RF Beamforming Transceivers for mmWave and Beyond
Phased arrays are used in transceivers at millimeter wave (mmW) and higher frequencies to
account for path losses and produce extremely directional beamforming gains. Spatial signal
leakage, however, may lower the signal-to-interference-plus-noise ratios (SINRs) of other users
in different directions, hence reducing their throughputs. The challenge of error-free signal
detection in the presence of spatial interference frequently calls for complicated, power-hungry
radio frequency (RF) components with a high dynamic range to deliver the required SINRs.
Most interference reduction techniques, both in theory and in practice, require one to control the
amplitude of the antenna paths, which results in inefficient use of available power by the power
amplifiers, reducing effective isotropic radiated power (EIRP) and, as a result, coverage.
This thesis explores several dynamic beamforming scenarios and strategies for decreasing
interference in phased array systems at mmW and higher frequencies. In systems that have
multiple beams, it explores the possibility of using crosscoupled signals to eliminate inter-beam
interference (IBI) that affects both transmit and receive beamformers. This assumes that a radio
system like 5GNR is aware of interferers in both uplink and downlink (i.e., transmit and receive
directions). As the relative bandwidth increases, beam squint, or frequency dependent
directivity, limits the wideband IBI cancellation by changing the level and direction of the
spatial null towards the interferer. To address the wideband issue the crosscoupled signal
approach is further refined, and an analysis of wideband IBI cancellation is also provided.
This thesis also provides a method of stacking uniform linear arrays (ULAs) of various sizes
to eliminate sidelobes and produce nulls in the radiated beam pattern. The stacking subarrays
approach is designed with predetermined performance constraints to guarantee that the
implementation is viable and to enhance sidelobe reduction and null out any known
interference. Moreover, this thesis includes a study on improving the quantization of analog
beamformers to take advantage of interference cancellation in multibeam phased arrays. In this
thesis, the approaches examined for spatial interference reduction are validated through
theoretical analysis, simulations, and some practical assessments utilizing over-the-air (OTA)
measurements.
account for path losses and produce extremely directional beamforming gains. Spatial signal
leakage, however, may lower the signal-to-interference-plus-noise ratios (SINRs) of other users
in different directions, hence reducing their throughputs. The challenge of error-free signal
detection in the presence of spatial interference frequently calls for complicated, power-hungry
radio frequency (RF) components with a high dynamic range to deliver the required SINRs.
Most interference reduction techniques, both in theory and in practice, require one to control the
amplitude of the antenna paths, which results in inefficient use of available power by the power
amplifiers, reducing effective isotropic radiated power (EIRP) and, as a result, coverage.
This thesis explores several dynamic beamforming scenarios and strategies for decreasing
interference in phased array systems at mmW and higher frequencies. In systems that have
multiple beams, it explores the possibility of using crosscoupled signals to eliminate inter-beam
interference (IBI) that affects both transmit and receive beamformers. This assumes that a radio
system like 5GNR is aware of interferers in both uplink and downlink (i.e., transmit and receive
directions). As the relative bandwidth increases, beam squint, or frequency dependent
directivity, limits the wideband IBI cancellation by changing the level and direction of the
spatial null towards the interferer. To address the wideband issue the crosscoupled signal
approach is further refined, and an analysis of wideband IBI cancellation is also provided.
This thesis also provides a method of stacking uniform linear arrays (ULAs) of various sizes
to eliminate sidelobes and produce nulls in the radiated beam pattern. The stacking subarrays
approach is designed with predetermined performance constraints to guarantee that the
implementation is viable and to enhance sidelobe reduction and null out any known
interference. Moreover, this thesis includes a study on improving the quantization of analog
beamformers to take advantage of interference cancellation in multibeam phased arrays. In this
thesis, the approaches examined for spatial interference reduction are validated through
theoretical analysis, simulations, and some practical assessments utilizing over-the-air (OTA)
measurements.
Last updated: 26.9.2024