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Recently, the millimeter wave (mmWave) bands have been investigated as a means to support the foreseen extreme data rate demands of next-generation cellular networks (5G). However, in order to overcome the severe isotropic path loss and the harsh propagation experienced at such high frequencies, a dense base station deployment is required, which may be infeasible because of the unavailability of fiber drops to provide wired backhauling. To address this challenge, the 3GPP is investigating the concept of Integrated Access and Backhaul (IAB), i.e., the possibility of providing wireless backhaul to the mobile terminals. In this paper, we (i) extend the capabilities of the existing mmWave module for ns-3 to support advanced IAB functionalities, and (ii) evaluate the end-to-end performance of the IAB architecture through system-level full-stack simulations in terms of experienced throughput and communication latency. We finally provide guidelines on how to design optimal wireless backhaul solutions in the presence of resource-constrained and traffic-congested mmWave scenarios., Comment: 8 pages, 5 figures, 1 table. Accepted at IEEE CAMAD, September 2018, Barcelona, Spain

The communication at mmWave frequencies is a promising enabler for ultra high data rates in the next generation of mobile cellular networks (5G). The harsh propagation environment at such high frequencies, however, demands a dense base station deployment, which may be infeasible because of the unavailability of fiber drops to provide wired backhauling. To address this issue, 3GPP has recently proposed a Study Item on Integrated Access and Backhaul (IAB), i.e., on the possibility of providing the wireless backhaul together with the radio access to the mobile terminals. The design of IAB base stations and networks introduces new research challenges, especially when considering the demanding conditions at mmWave frequencies. In this paper we study different path selection techniques, using a distributed approach, and investigate their performance in terms of hop count and bottleneck Signal-to-Noise-Ratio (SNR) using a channel model based on real measurements. We show that there exist solutions that decrease the number of hops without affecting the bottleneck SNR and provide guidelines on the design of IAB path selection policies., Comment: 7 pages, 4 figures, 3 tables. Please cite it as M. Polese, M. Giordani, A. Roy, D. Castor and M. Zorzi, "Distributed Path Selection Strategies for Integrated Access and Backhaul at mmWaves," 2018 IEEE Global Communications Conference (GLOBECOM), Abu Dhabi, United Arab Emirates, 2018

The next generation of cellular networks will exploit mmWave frequencies to dramatically increase the network capacity. The communication at such high frequencies, however, requires directionality to compensate the increase in propagation loss. Users and base stations need to align their beams during both initial access and data transmissions, to ensure the maximum gain is reached. The accuracy of the beam selection, and the delay in updating the beam pair or performing initial access, impact the end-to-end performance and the quality of service. In this paper we will present the beam management procedures that 3GPP has included in the NR specifications, focusing on the different operations that can be performed in Standalone (SA) and in Non-Standalone (NSA) deployments. We will also provide a performance comparison among different schemes, along with design insights on the most important parameters related to beam management frameworks., Comment: 7 pages, 5 figures, 1 table. Please cite it as M. Giordani, M. Polese, A. Roy, D. Castor and M. Zorzi, "Standalone and Non-Standalone Beam Management for 3GPP NR at mmWaves," in IEEE Communications Magazine, vol. 57, no. 4, pp. 123-129, April 2019

The use of millimeter wave (mmWave) frequencies for communication will be one of the innovations of the next generation of cellular mobile networks (5G). It will provide unprecedented data rates, but is highly susceptible to rapid channel variations and suffers from severe isotropic pathloss. Highly directional antennas at the transmitter and the receiver will be used to compensate for these shortcomings and achieve sufficient link budget in wide area networks. However, directionality demands precise alignment of the transmitter and the receiver beams, an operation which has important implications for control plane procedures, such as initial access, and may increase the delay of the data transmission. This paper provides a comparison of measurement frameworks for initial access in mmWave cellular networks in terms of detection accuracy, reactiveness and overhead, using parameters recently standardized by the 3GPP and a channel model based on real-world measurements. We show that the best strategy depends on the specific environment in which the nodes are deployed, and provide guidelines to characterize the optimal choice as a function of the system parameters., Comment: 8 pages, 7 figures, 3 tables, accepted to the IEEE 17th Annual Mediterranean Ad Hoc Networking Workshop (Med-Hoc-Net). arXiv admin note: substantial text overlap with arXiv:1804.01908

The millimeter wave (mmWave) frequencies offer the availability of huge bandwidths to provide unprecedented data rates to next-generation cellular mobile terminals. However, mmWave links are highly susceptible to rapid channel variations and suffer from severe free-space pathloss and atmospheric absorption. To address these challenges, the base stations and the mobile terminals will use highly directional antennas to achieve sufficient link budget in wide area networks. The consequence is the need for precise alignment of the transmitter and the receiver beams, an operation which may increase the latency of establishing a link, and has important implications for control layer procedures, such as initial access, handover and beam tracking. This tutorial provides an overview of recently proposed measurement techniques for beam and mobility management in mmWave cellular networks, and gives insights into the design of accurate, reactive and robust control schemes suitable for a 3GPP NR cellular network. We will illustrate that the best strategy depends on the specific environment in which the nodes are deployed, and give guidelines to inform the optimal choice as a function of the system parameters., Comment: 22 pages, 19 figures, 10 tables, published in IEEE Communications Surveys and Tutorials. Please cite it as M. Giordani, M. Polese, A. Roy, D. Castor and M. Zorzi, "A Tutorial on Beam Management for 3GPP NR at mmWave Frequencies," in IEEE Communications Surveys & Tutorials, vol. 21, no. 1, pp. 173-196, First quarter 2019

The superconductor-insulator transition (SIT) is an excellent example for a quantum phase transition at zero temperature, dominated by quantum fluctuations. These are expected to be very prominent close to the quantum critical point. So far most of the experimental study of the SIT has concentrated on transport properties and tunneling experiments which provide indirect information on criticality close to the transition. Here we present an experiment uniquely designed to study the evolution of quantum fluctuations through the quantum critical point. We utilize the Nernst effect, which has been shown to be effective in probing superconducting fluctuation. We measure the Nernst coefficient in amorphous indium oxide films tuned through the SIT and find a large signal on both the superconducting and the insulating sides which peaks close to the critical point. The transverse Peltier coefficient, $\alpha_{xy}$ which is the thermodynamic quantity extracted from these measurements, follows quantum critical scaling with critical exponents $\nu \sim 0.7$ and $z \sim 1$ which is consistent with a clean XY model in 2+1 dimensions., Comment: 6 pages, 3 figures

We present a formal logic for quantitative reasoning about security properties of network protocols. The system allows us to derive concrete security bounds that can be used to choose key lengths and other security parameters. We provide axioms for reasoning about digital signatures and random nonces, with security properties based on the concrete security of signature schemes and pseudorandom number generators (PRG). The formal logic supports first-order reasoning and reasoning about protocol invariants, taking concrete security bounds into account. Proofs constructed in our logic also provide conventional asymptotic security guarantees because of the way that concrete bounds accumulate in proofs. As an illustrative example, we use the formal logic to prove an authentication property with concrete bounds of a signature-based challenge-response protocol.