We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Random graphs

This tutorial presents an overview of the technological advances in millimeter-wave (mm-wave) circuit components, antennas, and propagation that will soon allow 60-GHz transceivers to provide multigigabit per second (multi-Gb/s) wireless communication data transfers in the consumer marketplace. Our goal is to help engineers understand the convergence of communications, circuits, and antennas, as the emerging world of subterahertz and terahertz wireless communications will require understanding at the intersections of these areas. This paper covers trends and recent accomplishments in a wide range of circuits and systems topics that must be understood to create massively broadband wireless communication systems of the future. In this paper, we present some evolving applications of massively broadband wireless communications, and use tables and graphs to show research progress from the literature on various radio system components, including on-chip and in-package antennas, radio-frequency (RF) power amplifiers (PAs), low-noise amplifiers (LNAs), voltage-controlled oscillators (VCOs), mixers, and analog-to-digital converters (ADCs). We focus primarily on silicon-based technologies, as these provide the best means of implementing very low-cost, highly integrated 60-GHz mm-wave circuits. In addition, the paper illuminates characterization techniques that are required to competently design and fabricate mm-wave devices in silicon, and illustrates effects of the 60-GHz RF propagation channel for both in-building and outdoor use. The paper concludes with an overview of the standardization and commercialization efforts for 60-GHz multi-Gb/s devices, and presents a novel way to compare the data rate versus power efficiency for future broadband devices.

http://faculty.poly.edu/~tsr/wp-content/uploads/publications/abstract17.pdf

State of the Art in 60-GHz Integrated Circuits and Systems for Wireless Communications

Conventional evolutionary game theory predicts that natural selection favours the selfish and strong even though cooperative interactions thrive at all levels of organization in living systems. Recent investigations demonstrated that a limiting factor for the evolution of cooperative interactions is the way in which they are organized, cooperators becoming evolutionarily competitive whenever individuals are constrained to interact with few others along the edges of networks with low average connectivity. Despite this insight, the conundrum of cooperation remains since recent empirical data shows that real networks exhibit typically high average connectivity and associated single-to-broad–scale heterogeneity. Here, a computational model is constructed in which individuals are able to self-organize both their strategy and their social ties throughout evolution, based exclusively on their self-interest. We show that the entangled evolution of individual strategy and network structure constitutes a key mechanism for the sustainability of cooperation in social networks. For a given average connectivity of the population, there is a critical value for the ratio W between the time scales associated with the evolution of strategy and of structure above which cooperators wipe out defectors. Moreover, the emerging social networks exhibit an overall heterogeneity that accounts very well for the diversity of patterns recently found in acquired data on social networks. Finally, heterogeneity is found to become maximal when W reaches its critical value. These results show that simple topological dynamics reflecting the individual capacity for self-organization of social ties can produce realistic networks of high average connectivity with associated single-to-broad–scale heterogeneity. On the other hand, they show that cooperation cannot evolve as a result of “social viscosity” alone in heterogeneous networks with high average connectivity, requiring the additional mechanism of topological co-evolution to ensure the survival of cooperative behaviour.

Cooperation prevails when individuals adjust their social ties

The goal of this piece is to survey the developing and rapidly growing literature on the economic consequences of COVID-19 and the governmental responses, and to synthetize the insights emerging from a very large number of studies. This survey: (i) provides an overview of the data sets and the techniques employed to measure social distancing and COVID-19 cases and deaths; (ii) reviews the literature on the determinants of compliance with and the effectiveness of social distancing; (iii) mentions the macroeconomic and financial impacts including the modelling of plausible mechanisms; (iv) summarizes the literature on the socioeconomic consequences of COVID-19, focusing on those aspects related to labor, health, gender, discrimination, and the environment; and (v) summarizes the literature on public policy responses.

https://www.econstor.eu/bitstream/10419/222316/1/GLO-DP-0601.pdf

A literature review of the economics of COVID-19

A fully-integrated FMCW radar system for automotive applications operating at 77 GHz has been proposed. Utilizing a fractional- synthesizer as the FMCW generator, the transmitter linearly modulates the carrier frequency across a range of 700 MHz. The receiver together with an external baseband processor detects the distance and relative speed by conducting an FFT-based algorithm. Millimeter-wave PA and LNA are incorporated on chip, providing sufficient gain, bandwidth, and sensitivity. Fabricated in 65-nm CMOS technology, this prototype provides a maximum detectable distance of 106 meters for a mid-size car while consuming 243 mW from a 1.2-V supply.

A Fully-Integrated 77-GHz FMCW Radar Transceiver in 65-nm CMOS Technology

A systematic methodology for layout optimization of active devices for millimeter-wave (mm-wave) application is proposed. A hybrid mm-wave modeling technique was developed to extend the validity of the device compact models up to 100 GHz. These methods resulted in the design of a customized 90 nm device layout which yields an extrapolated of 300 GHz from an intrinsic device . The device is incorporated into a low-power 60 GHz amplifier consuming 10.5 mW, providing 12.2 dB of gain, and an output of 4 dBm. An experimental three-stage 104 GHz tuned amplifier has a measured peak gain of 9.3 dB. Finally, a Colpitts oscillator operating at 104 GHz delivers up to 5 dBm of output power while consuming 6.5 mW.

Millimeter-Wave Devices and Circuit Blocks up to 104 GHz in 90 nm CMOS

ObjectiveAlthough anecdotal evidence indicates the effectiveness of coronavirus disease 2019 (COVID-19) social-distancing policies, their effectiveness in relation to what is driven by public aware...

https://journals.sagepub.com/doi/pdf/10.1177/0033354920976575

The Immediate Effect of COVID-19 Policies on Social-Distancing Behavior in the United States.

A customized 90nm device layout yields an extrapolated fmax of 300GHz. The device is incorporated into a low-power 60GHz amplifier consuming 10.5mW, providing 12dB of gain, and an output P1dB of 4dBm. An experimental 3-stage 104GHz amplifier has a measured peak gain of 9.3dB. Finally, a Colpitts oscillator at 104GHz delivers up to -5dBm of output power while consuming 6mW.

Low-Power mm-Wave Components up to 104GHz in 90nm CMOS

Anecdotal evidence points to the effectiveness of COVID-19 social distancing policies, however, their effectiveness vis-a-vis what is driven by public awareness and voluntary actions have not been studied. Policy variations across US states create a natural experiment to study the causal impact of each policy. Using a difference-in-differences methodology, location-based mobility, and daily state-level data on COVID-19 tests and confirmed cases, we rank policies based on their effectiveness. We show that statewide stay-at-home orders had the strongest causal impact on reducing social interactions. In contrast, most of the expected impact of more lenient policies were already reaped from non-policy mechanisms. Moreover, stay-at-home policy results in a steady decline in confirmed cases, starting from ten days after implementation and reaching a 37% decrease after fifteen days, consistent with the testing practices and incubation period of the disease.

/pdf/the-immediate-effect-of-covid-19-policies-on-social-1ktfj80xkl.pdf

The Immediate Effect of COVID-19 Policies on Social Distancing Behavior in the United States

30 GHz low noise amplifier was designed and fabricated in a 90 nm digital CMOS process. The mm-wave amplifier has a peak gain of 20 dB at 28.5 GHz and a 3 dB bandwidth of 2.6 GHz with the input and output matching better than 12 dB and 17 dB over the entire band respectively. The NF is 2.9 dB at 28 GHz and less than 4.2 dB across the band and it can deliver 2 dBm of power to a matched load at its 1 dB compression point. The amplifier has a measured linearity of IIIP3=-7.5 dBm. It consumes 16.25 mW of power using a low supply voltage of 1 V and occupies an area (excluding the pads) of 1600 mum x 420 mum.

Babak Heydari

Papers

Millimeter-Wave Devices and Circuit Blocks up to 104 GHz in 90 nm CMOS

The Immediate Effect of COVID-19 Policies on Social-Distancing Behavior in the United States.

Low-Power mm-Wave Components up to 104GHz in 90nm CMOS

The Immediate Effect of COVID-19 Policies on Social Distancing Behavior in the United States

30 GHz CMOS Low Noise Amplifier