There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

http://www.eecs.ucf.edu/~dcm/Teaching/COT4810-Spring2011/Literature/SensorNetworksSurvey.pdf

Wireless sensor networks: a survey

We develop and analyze low-complexity cooperative diversity protocols that combat fading induced by multipath propagation in wireless networks. The underlying techniques exploit space diversity available through cooperating terminals' relaying signals for one another. We outline several strategies employed by the cooperating radios, including fixed relaying schemes such as amplify-and-forward and decode-and-forward, selection relaying schemes that adapt based upon channel measurements between the cooperating terminals, and incremental relaying schemes that adapt based upon limited feedback from the destination terminal. We develop performance characterizations in terms of outage events and associated outage probabilities, which measure robustness of the transmissions to fading, focusing on the high signal-to-noise ratio (SNR) regime. Except for fixed decode-and-forward, all of our cooperative diversity protocols are efficient in the sense that they achieve full diversity (i.e., second-order diversity in the case of two terminals), and, moreover, are close to optimum (within 1.5 dB) in certain regimes. Thus, using distributed antennas, we can provide the powerful benefits of space diversity without need for physical arrays, though at a loss of spectral efficiency due to half-duplex operation and possibly at the cost of additional receive hardware. Applicable to any wireless setting, including cellular or ad hoc networks-wherever space constraints preclude the use of physical arrays-the performance characterizations reveal that large power or energy savings result from the use of these protocols.

Cooperative diversity in wireless networks: Efficient protocols and outage behavior

Cognitive radio is viewed as a novel approach for improving the utilization of a precious natural resource: the radio electromagnetic spectrum. The cognitive radio, built on a software-defined radio, is defined as an intelligent wireless communication system that is aware of its environment and uses the methodology of understanding-by-building to learn from the environment and adapt to statistical variations in the input stimuli, with two primary objectives in mind: /spl middot/ highly reliable communication whenever and wherever needed; /spl middot/ efficient utilization of the radio spectrum. Following the discussion of interference temperature as a new metric for the quantification and management of interference, the paper addresses three fundamental cognitive tasks. 1) Radio-scene analysis. 2) Channel-state estimation and predictive modeling. 3) Transmit-power control and dynamic spectrum management. This work also discusses the emergent behavior of cognitive radio.

/pdf/cognitive-radio-brain-empowered-wireless-communications-9m6gu0vz1z.pdf

Cognitive radio: brain-empowered wireless communications

Networking together hundreds or thousands of cheap microsensor nodes allows users to accurately monitor a remote environment by intelligently combining the data from the individual nodes. These networks require robust wireless communication protocols that are energy efficient and provide low latency. We develop and analyze low-energy adaptive clustering hierarchy (LEACH), a protocol architecture for microsensor networks that combines the ideas of energy-efficient cluster-based routing and media access together with application-specific data aggregation to achieve good performance in terms of system lifetime, latency, and application-perceived quality. LEACH includes a new, distributed cluster formation technique that enables self-organization of large numbers of nodes, algorithms for adapting clusters and rotating cluster head positions to evenly distribute the energy load among all the nodes, and techniques to enable distributed signal processing to save communication resources. Our results show that LEACH can improve system lifetime by an order of magnitude compared with general-purpose multihop approaches.

/pdf/an-application-specific-protocol-architecture-for-wireless-1s7y9fiv40.pdf

An application-specific protocol architecture for wireless microsensor networks

Adopting the entrepreneurial model

System
zum Orten der Position von einer oder mehreren drahtlosen Vorrichtungen
(100) in einer physischen Umgebung, mit: einem ortspezifischen
Umgebungsmodell der physischen Umgebung, das Darstellungen einer
Mehrzahl von drahtlosen oder optischen Kommunikationskomponenten,
die in der physischen Umgebung aufgestellt sind, aufweist; einer
Mehrzahl von Tabellen (107; 802; 1502, 1503), wobei jede derselben
einem spezifischen Punkt (804; 1504) in der physischen Umgebung,
die durch das ortspezifische Umgebungsmodell modelliert ist, zugeordnet
ist, und jede eine oder mehrere HF-Kanalcharakteristika oder Leistungsmetriken
von mindestens einer drahtlosen oder optischen Vorrichtung (100)
aufweist; einer oder mehreren Messvorrichtungen (101; 808;
1508), die bei einem oder mehreren Orten in der physischen Umgebung
positioniert oder positionierbar sind, wobei die eine oder mehreren
Messvorrichtungen HF-Kanalcharakteristika oder Leistungsmetriken
messen; einer Computersteuerung (104), die gemessene HF-Kanalcharakteristika
oder Leistungsmetriken mit HF-Kanalcharakteristika oder Leistungsmetriken
in der Mehrzahl von Tabellen (107; 802; 1502, 1503) vergleicht (1002)
und einen oder mehrere Orte von...

System, Verfahren und Vorrichtung zum Bestimmen und Verwenden einer Position von drahtlosen Vorrichtungen oder einer Infrastruktur zur Verbesserung eines drahtlosen Netzes

Wireless communication in millimeter wave spectrum is poised to provide the latency and bandwidth needed for advanced use cases unfeasible at lower frequencies. Despite the market potential of vehicular communication networks, investigations into the millimeter wave vehicular channel are lacking. In this paper, we present a detailed overview of a novel 1 GHz wide, multi-antenna vehicle to vehicle directional channel sounding and measurement platform operating at 28 GHz. The channel sounder uses two 256-element phased arrays at the transmitter vehicle and four 64-element arrays at the receiver vehicle, with the receiver measuring 116 different directional beams in less than 1 millisecond. By measuring the full multi-beam channel impulse response at large bandwidths, our system provides unprecedented insight in instantaneous mobile vehicle to vehicle channels. The system also uses centimeter-level global position tracking and 360 degree video capture to provide additional contextual information for joint communication and sensing applications. An initial measurement campaign was conducted on highway and surface streets in Austin, Texas. We show example data that highlights the sensing capability of the system. Preliminary results from the measurement campaign show that bumper mounted mmWave arrays provide rich scattering in traffic as well a provide significant directional diversity aiding towards high reliability vehicular communication. Additionally, potential waveguide effects from high traffic in lanes can also extend the range of mmWave signals significantly.

A Real-Time Millimeter Wave V2V Channel Sounder

Summary form only given. This paper explores an emerging frontier for wireless communications: campus and indoor wireless coverage. Proper design of an indoor wireless solution involves RF performance, cost, specific customer requests, ease of installation and ease of maintenance. Tradeoffs exist in the selection of an indoor wireless system from the various types available, based on cost versus performance. Optimum placement for system components depends on objectives such as coverage with minimal use of antennas or cables, and disguise for minimum visual impact. Currently available service types for in-building wireless include indoor public voice and data service, wireless office service (WOS) and wireless LAN. Customization and archival issues based on user adoption and growth expectations impact the selection and design decisions for in-building systems. Finally, the paper highlights the involvement and support of IT staff in installation and deployment strategies for successful and efficient design of any indoor wireless solution.

Design efficiencies for indoor wireless

Small-cell cellular base stations are going to be used for mmWave and sub-THz communication systems to provide multi-Gbps data rates and reliable coverage to mobile users. This paper analyzes the base station coverage of sub-THz communication systems and the system performance in terms of spectral efficiency through Monte Carlo simulations for both single-cell and multi-cell cases. The simulations are based on realistic channel models derived from outdoor field measurements at 142 GHz in urban microcell (UMi) environments conducted in downtown Brooklyn, New York. The single-cell base station can provide a downlink coverage area with a radius of 200 m and the 7-cell system can provide a downlink coverage area with a radius of 400 m at 142 GHz. Using a 1 GHz downlink bandwidth and 100 MHz uplink bandwidth, the 7-cell system can provide about 4.5 Gbps downlink average data rate and 410 Mbps uplink average data rate at 142 GHz.

Theodore S. Rappaport

Papers

Adopting the entrepreneurial model

System, Verfahren und Vorrichtung zum Bestimmen und Verwenden einer Position von drahtlosen Vorrichtungen oder einer Infrastruktur zur Verbesserung eines drahtlosen Netzes

A Real-Time Millimeter Wave V2V Channel Sounder

Design efficiencies for indoor wireless

Sub-Terahertz Wireless Coverage Analysis at 142 GHz in Urban Microcell