On the design and performance analysis of mmWave-enabled next generation of wireless networks

Abstract

The hush of expectancy of a millimeter-wave enabled next generation (i.e., 5G) of communication systems are upon us. As with every new technology, there are inevitable teething issues and obstacles to overcome before finding its true commercial value. Millimeter-wave technology has had its fair share of cynics in the past few years, with questions arising about its efficacy for transmission over long distances, how well it can penetrate through walls, and even if rain or a user’s hand might block the signal. These issues are valid, but most of them have been tackled with innovative solutions in recent years. In addition, millimeter-wave and 5G are often used synonymously, but there are critical differences between the two. The millimeter-wave spectrum is just one part of the frequency band available to future 5G networks. The typical microwave frequencies or sub-6GHz spectrum will also be part of the standard. Among other benefits, the coexistence of these two spectra will offer better coverage and data speeds to customers. Since the millimeter-wave technology is almost ready to make its public debut on the stage of the commercial tech-world, the main theme of our research project revolves around design and performance analysis of the key enablers of 5G, such as millimeter-wave communications, massive multiple-input multiple-output systems, and heterogeneous networks. More specifically, this thesis focuses on (i) the coexistence of millimeter wave, and sub-6GHz frequencies in a heterogeneous network and (ii) millimeter-wave enabled wideband and ultra wideband communication systems. In this context, the second chapter of this thesis presents a detailed analysis and simulation model of a half-duplex two-tier heterogeneous network employing different frequency bands (i.e., sub-6GHz and millimeter wave). Tools from stochastic geometry are used to model an environment, where users’ equipment have the liberty to choose different base stations for uplink and downlink transmissions, called decoupled wireless access. The key performance metrics, such as the probability of users’ equipment association, the distribution of the distances between the users’ equipment and their tagged base stations, and spectral efficiency are analyzed and evaluated for various pragmatic deployment scenarios. The third chapter of this thesis presents a performance analysis of a full-duplex two-tier heterogeneous network with decoupled access employing different frequency bands (i.e., sub-6GHz and millimeter wave). The novelty of the derived analytical model is that it accommodates variable transmit powers and different path loss exponents for different tiers, and accounts for the interference in millimeter-wave networks. To the best of our knowledge, it is the first analytical model that comprehensively encapsulates the characteristics of dense to ultra-dense networks. Hence, the comprehensive nature of the proposed analytical model can help us understand the performance limits of a network for diverse deployment scenarios. The fourth and fifth chapters of this thesis focus on an issue in wideband and ultra-wideband massive multiple input multiple-output communication systems, i.e., beam squinting. The main attraction in the millimeter-wave band is its large available bandwidth. Therefore wideband and ultra-wideband communication systems will become an unavoidable reality soon. Though wideband and ultra wideband communication systems have the potential to increase the achievable capacity significantly, such communication also raises a new issue called beamsquinting, limiting the achievable capacity. The beam-squinting did not get enough prominence to become the blue-eyed problem of the research community of mobile communications until recently. The reason for this deliberate neglect is the fact that, so far, almost all mobile communication systems work on narrowband signals, which by their very nature, make the beamsquinting issue negligible. In chapter four, a novel transceiver architecture for ultra-wideband massive multiple-input multiple-output communication is proposed to mitigate beam-squinting effects. The advantage of the proposed design is that it does not rely on any compensation in the digital domain. Therefore it is suitable for computational power-constrained or delay-sensitive applications that do not have the liberty to calculate large compensation matrices in the digital domain. Moreover, the fifth chapter of this thesis highlights the potential use of hypersurfaces that can be exploited to mitigate the beam-squinting issue in a millimeter-wave enabled ultra-wideband communication systems.

Date	29 Oct 2020
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Georges Kaddoum (Supervisor) & Naïm Batani (Co-supervisor)