Rate Optimal design of a Wireless Backhaul Network using TV White Space

The penetration of wireless broadband services in remote areas has primarily been limited due to the lack of economic incentives that service providers encounter in sparsely populated areas. Besides, wireless backhaul links like satellite and microwave are either expensive or require strict line of sight communication making them unattractive. TV white space channels with their desirable radio propagation characteristics can provide an excellent alternative for engineering backhaul networks in areas that lack abundant infrastructure. Specifically, TV white space channels can provide "free wireless backhaul pipes" to transport aggregated traffic from broadband sources to fiber access points. In this paper, we investigate the feasibility of multi-hop wireless backhaul in the available white space channels by using noncontiguous Orthogonal Frequency Division Multiple Access (NC-OFDMA) transmissions between fixed backhaul towers. Specifically, we consider joint power control, scheduling and routing strategies to maximize the minimum rate across broadband towers in the network. Depending on the population density and traffic demands of the location under consideration, we discuss the suitable choice of cell size for the backhaul network. Using the example of available TV white space channels in Wichita, Kansas (a small city located in central USA), we provide illustrative numerical examples for designing such wireless backhaul network

Traveling wave packets of total electron content disturbances as deduced from global GPS network data

We identified a new class of mid-latitude medium-scale traveling ionospheric disturbances (MS TIDs), viz. traveling wave packets (TWPs) of total electron content (TEC) disturbances. For the first time, the morphology of TWPs is presented for 105 days. Using the technique of GPS interferometry of TIDs we carried out a detailed analysis of the spatial-temporal properties of TWPs by considering an example of the most conspicuous manifestation of TWPs on October 18, 2001 over California, USA. The velocity and direction of TWPs correspond to those of mid-latitude MS TIDs obtained previously from analyzing the phase characteristics of HF radio signals as well as signals from geostationary satellites and discrete cosmic radio sources.Comment: LaTeX2.09, 28 pages, 9 figure

Wirelessly Powered Backscatter Communication Networks: Modeling, Coverage and Capacity

Future Internet-of-Things (IoT) will connect billions of small computing devices embedded in the environment and support their device-to-device (D2D) communication. Powering this massive number of embedded devices is a key challenge of designing IoT since batteries increase the devices' form factors and battery recharging/replacement is difficult. To tackle this challenge, we propose a novel network architecture that enables D2D communication between passive nodes by integrating wireless power transfer and backscatter communication, which is called a wirelessly powered backscatter communication (WP-BackCom) network. In the network, standalone power beacons (PBs) are deployed for wirelessly powering nodes by beaming unmodulated carrier signals to targeted nodes. Provisioned with a backscatter antenna, a node transmits data to an intended receiver by modulating and reflecting a fraction of a carrier signal. Such transmission by backscatter consumes orders-of-magnitude less power than a traditional radio. Thereby, the dense deployment of low-complexity PBs with high transmission power can power a large-scale IoT. In this paper, a WP-BackCom network is modeled as a random Poisson cluster process in the horizontal plane where PBs are Poisson distributed and active ad-hoc pairs of backscatter communication nodes with fixed separation distances form random clusters centered at PBs. The backscatter nodes can harvest energy from and backscatter carrier signals transmitted by PBs. Furthermore, the transmission power of each node depends on the distance from the associated PB. Applying stochastic geometry, the network coverage probability and transmission capacity are derived and optimized as functions of backscatter parameters, including backscatter duty cycle and reflection coefficient, as well as the PB density. The effects of the parameters on network performance are characterized.Comment: 28 pages, 11 figures, has been submitted to IEEE Trans. on Wireless Communicatio

ARIANNA: A radio detector array for cosmic neutrinos on the Ross Ice Shelf

ARIANNA (The Antarctic Ross Ice Shelf Antenna Neutrino Array) is a proposed 100 km^3 detector for ultra-high energy (above 10^17 eV) astrophysical neutrinos. It will study the origins of ultra-high energy cosmic rays by searching for the neutrinos produced when these cosmic rays interact with the cosmic microwave background. Over 900 independently operating stations will detect the coherent radio Cherenkov emission produced when astrophysical neutrinos with energy above 10^17 eV interact in the Antarctic Ross Ice Shelf. Each station will use 8 log periodic dipole antennas to look for short RF pulses, with the most important frequencies between 80 MHz and 1 GHz. By measuring the pulse polarization and frequency spectrum, the neutrino arrival direction can be determined. In one year of operation, the full array should observe a clear GZK neutrino signal, with different models predicting between 3 and 51 events, depending on the nuclear composition of the cosmic-rays and on the cosmic evolution of their sources.Comment: 8 pages, presented at SORMA12. Many small improvements, per referee comment

Fog Computing: A Taxonomy, Survey and Future Directions

In recent years, the number of Internet of Things (IoT) devices/sensors has increased to a great extent. To support the computational demand of real-time latency-sensitive applications of largely geo-distributed IoT devices/sensors, a new computing paradigm named "Fog computing" has been introduced. Generally, Fog computing resides closer to the IoT devices/sensors and extends the Cloud-based computing, storage and networking facilities. In this chapter, we comprehensively analyse the challenges in Fogs acting as an intermediate layer between IoT devices/ sensors and Cloud datacentres and review the current developments in this field. We present a taxonomy of Fog computing according to the identified challenges and its key features.We also map the existing works to the taxonomy in order to identify current research gaps in the area of Fog computing. Moreover, based on the observations, we propose future directions for research