Faisal Darbari

UHF white space network for rural smart grid communications

We present a white space communications test bed running in the Scottish Highlands and Islands, and discuss its feasibility for smart grid communications. The network aims to serve communities that have great potential for distributed generation of electricity, by means of wind, water, and tidal power. However, smart grid applications such as remote meter reading and load balancing are impaired by the scarcety or lack of communications infrastructure in remote rural areas such as the Scottish Highlands and Islands. We argue that the proposed system is based on a network of energy self-sufficient radio relay nodes that make it a robust and independent medium to support smart grid communications in rural settings.

Practical aspects of broadband access for rural communities using a cost and power efficient multi-hop/relay network

Wireless radio links present one option for rural broadband where population is sparse and many of the existing technologies such as optical fiber or broadband via DSL are not economical due to rugged/mountainous terrain. In this paper, we present a broadband test bed running in the Scottish Highlands and Islands, and discuss its feasibility for broadband access. In addition to a 5GHz network, the test-bed also provides an overlay UHF white space network sharing the same infrastructure. We argue that the proposed system is based on a network of energy self-sufficient radio relay nodes that makes it a robust and independent medium to support broadband communication in rural settings.

Enabling rural broadband via TV “white space”

The use of multiple frequency bands within a wireless network allows the advantages of each band to be exploited. In this paper we discuss how “HopScotch”, a rural wireless broadband access test bed running in the Scottish Highlands and Islands, uses both 5 GHz and ultra high frequency “white space” bands to offer large data rates and expansive coverage whilst reducing the number of base stations or required transmission power. This reduction in energy consumption allows HopScotch to provide a low-cost and green solution for rural broadband delivery.

Channel and Interference Analysis for Wireless Sensor Networks

This paper presents preliminary investigations of the short range (~10 cm) narrowband wireless channel appropriate to specks operating in the 2.4 GHz ISM band. Path loss measurements have been made in the laboratory using rectaxial antennas at 2.45 GHz. The transmitted signal is an unmodulated carrier and the receiver is a spectrum analyzer. Characterization of signal power variations are important for system design and so path loss and fading models have been derived. The paper presents a comprehensive narrowband channel model (including interference due to neighboring nodes) for application to asynchronous short-range wireless networks. Medium access is assumed to be CSMA based and SIR will therefore depend on inhibition distance and antenna characteristics. Aggregated interference due to neighboring nodes has been calculated. Finally, cumulative SIR values have been used to construct link budgets and bit error rates.

Some preliminary short-range transmission loss measurements for wireless sensors deployed on indoor walls

Antenna characteristics and propagation are of fundamental importance to the coverage, capacity and service quality of all wireless communication systems. This paper presents short-range narrowband propagation measurements at 2.445 GHz for sensor network applications in an indoor environment. The effect of sensor node location on a wall has been determined for a pair of linearly polarised rectaxial antennas and a pair of ceramic patch antennas. Propagation loss has been measured as a function of (i) node separation (i.e. link length), (ii) node drop (i.e. vertical displacement of nodes below the ceiling) and (iii) node height (i.e. the perpendicular displacement of the nodes from the wall surface). It is observed that there is no significant effect of wall offset. In addition, the path loss exponent n generally increases with decreasing node drop.

Different Feeding Geometries for Planar Elliptical UWB Dipoles, and the Excitation of Leakage Current

This paper presents an assessment of the impact of feeding geometry and leakage current on the performance of several types of printed elliptical UWB dipoles. Using simulation and experimental verification this paper investigates the impact via field analysis, S-parameters, and pulse transmission. The UWB dipoles investigated are; a microstrip-fed UWB dipole, that had unpredictable behaviour due to the feed, which excited leakage current down the feed cable and, as a result, distorted the pulse. To minimise the leakage current, three other UWB dipoles were investigated. These were a CPW-fed UWB dipole with slots, a hybrid-feed UWB dipole, and a tapered-feed UWB dipole.

Partially reconfigurable TVWS transceiver for use in UK and US markets

With more and more countries opening up sections of unlicensed spectrum for use by TV White Space (TVWS) devices, the prospect of building a device capable of operating in more than one world region is appealing. The difficulty is that the locations of TVWS bands within the radio spectrum are not globally harmonised. With this problem in mind, the purpose of this paper is to present a TVWS transceiver design which is capable of being reconfigured to operate in both the UK and US spectrum. We present three different configurations: one covering the UK TVWS spectrum and the remaining two covering the various locations of the US TVWS bands.

TVWS filter bank transceiver on OMAP-L137 evaluation module

Communications devices operating in the TV white space (TVWS) spectrum will be strictly regulated, requiring compliance with spectral masks to protect incumbent users and sufficient frequency agility to allow access to numerous frequency bands at different times and locations. Therefore, future designs sampling directly at radio frequency (RF) have been proposed. The purpose of this paper is to demonstrate an implementation of such a transceiver at a scaled-down frequency implemented on the OMAP-L137 evaluation module, whereby the RF link can be replaced by the devices audio I/O, thus enabling easier observation and algorithm testing for students.

A low cost and power efficient TV white space technology solution for future rural broadband access networks

Wireless radio links present one option for rural broadband where population is sparse and many of the existing technologies such as optical fiber or broadband via DSL are not economical due to rugged/mountainous terrain. In this paper, we present a broadband test bed running in the Scottish Highlands and Islands, which is based on a relay network of low-power and cost efficient base stations. In addition to a 5GHz network, the test-bed also provides an overlay UHF white space network sharing the same infrastructure. The low-power base stations forming the relay nodes are supplied by wind and solar energy, establishing a green technology with low requirements on planning permission. Overall, the system offers a robust and independent medium to support broadband communication in rural settings.