Intelligent Reflecting Surface-assisted MU-MISO Systems with Imperfect Hardware: Channel Estimation and Beamforming Design

Poster (2021)

Intelligent reflecting surface (IRS), consisting of lowcost passive elements, is a promising technology for improving the spectral and energy efficiency of the fifth-generation (5G) and beyond networks ... [more ▼]

Intelligent reflecting surface (IRS), consisting of lowcost passive elements, is a promising technology for improving the spectral and energy efficiency of the fifth-generation (5G) and beyond networks. It is also noteworthy that an IRS can shape the reflected signal propagation. Most works in IRSassisted systems have ignored the impact of the inevitable residual hardware impairments (HWIs) at both the transceiver hardware and the IRS while any relevant works have addressed only simple scenarios, e.g., with single-antenna network nodes and/or without taking the randomness of phase noise at the IRS into account. In this work, we aim at filling up this gap by considering a general IRS-assisted multi-user (MU) multiple-input single-output (MISO) system with imperfect channel state information (CSI) and correlated Rayleigh fading. In parallel, we present a general computationally efficient methodology for IRS reflect beamforming (RB) optimization. Specifically, we introduce an advantageous channel estimation (CE) method for such systems accounting for the HWIs. Moreover, we derive the uplink achievable spectral efficiency (SE) with maximal-ratio combining (MRC) receiver, displaying three significant advantages being: 1) its closed-form expression, 2) its dependence only on large-scale statistics, and 3) its low training overhead. Notably, by exploiting the first two benefits, we achieve to perform optimization with respect to the that can take place only at every several coherence intervals, and thus, reduces significantly the computational cost compared to other methods which require frequent phase optimization. Among the insightful observations, we highlight that uncorrelated Rayleigh fading does not allow optimization of the SE, which makes the application of an IRS ineffective. Also, in the case that the phase drifts, describing the distortion of the phases in the RBM, are uniformly distributed, the presence of an IRS provides no advantage. The analytical results outperform previous works and are verified by Monte-Carlo (MC) simulations. [less ▲]

Linear response in large deviations theory: a method to compute non-equilibrium distributions

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Mixed Courts of the Colonial Era

in Ruiz Fabri, Helene (Ed.) Max Planck Encyclopedia of International Procedural Law (2021)

This entry provides a detailed and systematic account of mixed courts of the colonial era, which were a form of domestic courts with international participation established between the first half of the ... [more ▼]

This entry provides a detailed and systematic account of mixed courts of the colonial era, which were a form of domestic courts with international participation established between the first half of the nineteenth century and the first half of the twentieth century in non-Western polities. Serving as an alternative to consular jurisdiction in countries where Western states were unwilling to accept the jurisdiction of ordinary local courts over their nationals or their nationals’ interests, these courts blended domestic and international features. [less ▲]

Mixed Courts of Egypt

in Ruiz Fabri, Helene (Ed.) Max Planck Encyclopedia of International Procedural Law (2021)

This entry provides a detailed description and assessment of the Mixed Courts of Egypt (1875-1949), the most famous of the mixed courts of the colonial era. Established as an alternative to consular ... [more ▼]

This entry provides a detailed description and assessment of the Mixed Courts of Egypt (1875-1949), the most famous of the mixed courts of the colonial era. Established as an alternative to consular courts, the Mixed Courts of Egypt were formally Egyptian domestic courts, but had a foreign-majority bench and the mission to guarantee the treaty-based rights of foreigners against any possible infringements from the Egyptian State. [less ▲]

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The minimal length product over homology bases of manifolds

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