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Carlos Viteri - Dissertation.pdf (3.99 MB)

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Beamforming Techniques for Frequency-Selective and Millimeter-Wave Indoor Broadcast Channels

Viteri Mera, Carlos Andres
http://orcid.org/0000-0001-5583-2590
http://rave.ohiolink.edu/etdc/view?acc_num=osu152344603415358

Abstract Details

2018, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
Wireless communication networks have become ubiquitous in recent years. Current wireless applications are possible thanks to small WiFi cells that provide high-speed indoor coverage and outdoor macro-cells that support user mobility. Next generation wireless networks will use similar architectures to enable new applications such as augmented and virtual reality, the internet of things, ultra-high definition video streaming, and massive data transmission and storage. However, these applications require unprecedented high-speed data transfer capabilities enabled by large frequency bandwidths. Motivated by spectrum scarcity in bands below 6 GHz, previously unused millimeter-wave (mmWave) bands, where large bandwidths are available, are now considered for future wireless networks. The necessity for efficient communication techniques for such large bandwidths and mmWave frequencies is the main motivation for this dissertation, with a focus on the complex radiowave propagation conditions found in indoor environments. Propagation mechanisms such as multiple reflections, diffractions, and transmissions through walls are commonly found in indoor wireless communications, which cause variations in the received signal along its bandwidth (wideband or frequency-selective channels). Traditionally, antenna arrays have been used together with beamforming (linear processing) techniques to improve the system's performance. However, those techniques were designed for narrowband systems (e.g., zero-forcing or matched filtering) and their application to wideband systems requires additional processing that increases system's complexity. In the first part of this dissertation, we tackle the problem of beamforming in frequency-selective channels with two approaches: \emph{i}) we use the electromagnetic time-reversal (TR) effect to directly design novel wideband beamformers, and \emph{ii}) we generalize the block-diagonalization (BD) procedure used in narrowband channels to the frequency-selective case. For both approaches, we derive theoretical performance bounds under different propagation conditions and provide numerical simulations for various operation parameters. We found that these frequency-selective beamforming solutions require low-complexity receivers and can efficiently address problems such as inter-symbol interference and inter-user interference. In the second part of this dissertation, we focus on the design of beamforming procedures for wideband mmWave systems considering their specific hardware constraints and propagation characteristics. In this case, antenna arrays with tens of elements are commonly used to compensate for large propagation losses. Hybrid analog/digital beamforming, that combines phase-shifters in the RF domain with digital baseband processing, has been proposed to reduce hardware complexity. Thus, we introduce a novel hybrid beamforming algorithm for multiuser wideband mmWave systems. The algorithm accounts for hardware constraints and realistic antenna array effects such as beam squint, antenna coupling, and individual element radiation patterns. We provide numerical evaluations of the algorithm with both statistical and ray-tracing channel models. Results show that the algorithm enables multi-Gbps connectivity to multiple users in real-life scenarios with only a 3 dB performance loss with respect to ideal fully-digital beamforming with much simpler hardware.
Fernando Teixeira (Advisor)
192 p.
Electrical Engineering
Beamforming, antenna arrays, millimeter-wave communications, wireless local area networks, wireless communications

Recommended Citations

Citations

  • Viteri Mera, C. A. (2018). Beamforming Techniques for Frequency-Selective and Millimeter-Wave Indoor Broadcast Channels [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu152344603415358

    APA Style (7th edition)

  • Viteri Mera, Carlos. Beamforming Techniques for Frequency-Selective and Millimeter-Wave Indoor Broadcast Channels. 2018. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu152344603415358.

    MLA Style (8th edition)

  • Viteri Mera, Carlos. "Beamforming Techniques for Frequency-Selective and Millimeter-Wave Indoor Broadcast Channels." Doctoral dissertation, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu152344603415358

    Chicago Manual of Style (17th edition)

osu152344603415358
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This open access ETD is published by The Ohio State University and OhioLINK.