RHU is greatly proud of alumna Asmaa Abdallah who has successfully defended her PhD dissertation titled “Interference Mitigation in 5G Network Densification Technologies: Algorithms and Performance limits” on April 22, 2020 at the American University of Beirut. The presentation was done virtually amid the COVID 19 closures.
Dr. Asmaa Abdallah received her B.S. (with High Distinction) and M.S. degrees in computer and communications engineering from RHU in 2013 and 2015, respectively. In September 2015, she joined the accelerated Ph.D. program in the Electrical and Computer Engineering department at AUB.
She has been a research and teaching assistant at AUB since 2015. She was a research intern at Nokia Bell Labs in France from July 2019 till December 2019, where she worked on new hybrid automatic request (HARQ) mechanisms for long-delay channel in non-terrestrial networks (NTN). She is a current member of the executive committee of IEEE Young Professionals Lebanon’s Section.
Dr. Abdallah has authored more than 10 publications in international peer-reviewed journals and conferences. She also serves as a TPC member and a reviewer for many journals and conferences. Dr. Abdallah was the recipient of RHU’s Nazek Rafik Hariri Graduate Studies Award for 2013 having ranked first in her graduating class. She also received the Doctoral Research Student Lebanese National Council for Scientific Research (CNRS-L) award in September 2018.
Below is the detailed abstract of her thesis:
The advent of fifth generation (5G) wireless technology is expected to unleash an unprecedented boost in network capacity, spectral and energy efficiencies, and peak data rates, accompanied by a significant increase in the number of connected devices via ultra-low latency connections. To achieve these aggressive goals, network densification has emerged as a mainstream technology in 5G in various manifestations to improve the capacity and spectral efficiency: increasing the number of base stations, increasing the number of antennas per site (a.k.a. massive multiple-input multiple-output (MIMO)), deploying distributed cell-free massive MIMO, employing distributed device-to-device (D2D) communications, and applying non-orthogonal multiple access (NOMA) communications, among many others. However, interference, whether in the form of inter-user or inter-cell, remains the major bottleneck as we densify the networks and reuse the spectral resources, and cannot be eliminated if we rely on network-centric topologies. While the spatial dimensions available at the centralized and distributed massive MIMO base stations (BSs) can be leveraged to suppress interference at the user equipment (UE), new approaches for interference mitigation that take into consideration the underlying hardware constraints and impairments, as well as signaling overhead are needed. In addition, by exploiting the physical proximity of communicating devices, offloading traffic from network-centric entities to distributed D2D networks and increasing resource utilization via NOMA communications, adequate user pairing criteria and power allocation policies become attractive efficient interference mitigation schemes with affordable complexity and signaling overhead.
In this dissertation, we investigate the problem of efficient interference mitigation schemes for emerging network densification technologies in 5G communications from four different perspectives. First, we propose and analyze channel allocation (CA) and power control (PC) schemes to mitigate interference in a D2D underlaid cellular system modeled as a random network using stochastic geometry. Second, we extend the proposed interference mitigation techniques to consider NOMA MIMO systems. Third, in the context of massive MIMO systems, we propose and analyze the performance of various baseband processing schemes under low resolution analog-to-digital converters (ADCs). We analyze the uplink achievable rate by a massive MIMO system when the base station is equipped with a large number of low-resolution ADCs. We propose new techniques that account for the severe non-linearity effects of the coarse quantization and incorporate a pilot-based channel estimation error. Fourth, in the context of distributed massive MIMO systems, we study angle-domain processing techniques targeted for suppressing interference in frequency-division duplexing (FDD) based cell-free massive MIMO systems. Most prior work on cell-free (distributed) massive MIMO systems assume time-division duplexing mode, although FDD systems dominate current wireless standards. Efficient power control schemes are investigated for cell-free massive MIMO systems while considering the effect of backhaul power consumption.
