This paper presents a new theory, called the consumption factor theory, to analyze and compare energy efficient design choices for wireless communication networks. The approach presented here provides new methods for analyzing and comparing the power efficiency of communication systems, thus enabling a quantitative analysis and design approach for "green engineering" of communication systems. The consumption factor (CF) theory includes the ability to analyze and compare cascaded circuits, as well as the impact of propagation path loss on the total energy used for a wireless link. In this paper, we show several examples how the consumption factor theory allows engineers to compare and determine the most energy efficient architectures or designs of communication systems. One of the key concepts of the consumption factor theory is the power efficiency factor, which has implications for selecting network architectures or particular cascaded components. For example, the question of whether a relay should be used between a source and sink depends critically on the ratio of the source transmitter power-efficiency factor to the relay transmitter power-efficiency factor. The consumption factor theory presented here has implications for the minimum energy consumption per bit required to achieve error-free communication, and may be used to extend Shannon's fundamental limit theory in a general way. This work includes compact, extensible expressions for energy and power consumption per bit of a general communication system, and many practical examples and applications of this theory.

The growing demand for bandwidth intensive wireless applications and devices portend a future where millimeter-wave and sub-THz carrier frequencies will be used to provide massively broadband® bandwidths and many Giga-bits-per-second (Gbps) data rates in mobile environments [1]. Concurrently, the importance of energy efficiency for communication systems incentivizes discovery of new routing and access techniques that work in conjunction with power saving protocols to maximize battery life and improve power consumption. Wireless channels, as well as the wireless devices themselves, play a major role in determining both achievable data rates and power requirements. In this paper, we use the consumption factor [2] framework to quantify the impact of channel characteristics on both data rate performance and power consumption in a wireless link. Based on recent 38 GHz cellular propagation measurements [3], we demonstrate how future (5G) millimeter-wave cellular channels will impact the data rates and power requirements for future millimeter-wave cellular systems having cell radii less than a km. Analysis results presented here show how to include frequency-domain representations of the channel for use in the consumption factor analysis. A key result from the analysis is that, as massively broadband systems become more prevalent, it will be important to assess the ideal cell size to achieve the lowest energy consumption per pit. Higher bandwidth systems generally benefit form shorter transmission distances. As futuristic cellular standards contemplate the use of millimeter-wave frequencies for greater bandwidths, the work here may offer insight into how to analyze energy efficiency and performance.

As the cost of massively broadband® semiconductors continue to be driven down at millimeter wave (mm-wave) frequencies, there is great potential to use LMDS spectrum (in the 28-38 GHz bands) and the 60 GHz band for cellular/mobile and peer-to-peer wireless networks. This work presents urban cellular and peer-to-peer RF wideband channel measurements using a broadband sliding correlator channel sounder and steerable antennas at carrier frequencies of 38 GHz and 60 GHz, and presents measurements showing the propagation time delay spread and path loss as a function of separation distance and antenna pointing angles for many types of real-world environments. The data presented here show that at 38 GHz, unobstructed Line of Site (LOS) channels obey free space propagation path loss while non-LOS (NLOS) channels have large multipath delay spreads and can exploit many different pointing angles to provide propagation links. At 60 GHz, there is notably more path loss, smaller delay spreads, and fewer unique antenna angles for creating a link. For both 38 GHz and 60 GHz, we demonstrate empirical relationships between the RMS delay spread and antenna pointing angles, and observe that excess path loss (above free space) has an inverse relationship with transmitter-to-receiver separation distance.

Wireless systems require increasingly large system bandwidths that are only available at millimeter-wave frequencies. Such spectrum bands offer the potential for multi-gigabit-per-second data rates to low-cost massively broadband® devices. To enable mobile outdoor millimeter-wave cellular-type applications, it is necessary to determine the coverage potential of base stations in real-world environments. This paper presents the results of a measurement campaign of 38 GHz outdoor urban cellular channels using directional antennas at both the mobile and the base station, and assesses outage probabilities at two separate transmitter locations on the campus of The University of Texas at Austin. Our measurements demonstrate the viability of directional antennas and site-specific planning for future mm-wave cellular, and show that cell radii of ~200 M will provide a very high probability of coverage in an urban environment. As production costs for millimeter-wave technologies continue to fall [1], we envision millimeter-wave cellular systems with dense base station deployments as a cost effective means of delivering multi-Gbps data rates to mobile cell phone and internet users.

In this paper, we present an Open-Source web-based archiving system to organize and share wireless RF propagation measurement data, models, and simulation software in a centralized, standardized archive. This archiving system is based on Semantic Web ideas that will enable the wireless research community to easily share and access measured data and simulators provided by researchers across the globe. To begin development of the web-based archiving environment, we use a previously developed RF propagation simulator, SIRCIM, to represent the range of values, types of measurements, and file format types that would be needed to properly archive measurements from the research community at large. This paper also explores development issues and considerations required to build a Semantic Web on-line propagation channel measurement and modeling archiving system for global use.

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.

This paper reviews recent developments in vehicular radar at 60 GHz and above, with a focus on low cost integrated antennas. We investigate a number of radar and communication antenna systems that can be made inexpensively and in large volumes using standard CMOS semiconductor fabrication methods. As shown here, the electromagnetic characteristics of low cost CMOS processes are often not well understood when applied to mmWave and THz RF applications. Here, we describe several methodologies and measured results to understand electromagnetic behavior of integrated circuits and on-chip antenna performance in a 180 nm CMOS process up to 67 GHz. By gaining understanding of the electrical characteristics of older, lower cost semiconductor CMOS processes, it becomes possible to design mmWave on-chip antennas and other passive devices at extremely low cost and with great reliability.