OF THE DISSERTATION Cross-Layer Design for Wireless Networks Using Antenna Arrays by Ece Gelal Doctor of Philosophy, Graduate Program in Computer Science University of California, Riverside, August 2009 Professor Srikanth V. Krishnamurthy, Chairperson One of the major problems experienced by wireless multi-hop networks is the intermittent network connectivity, which is a consequence of fluctuat...

In this paper, we present a RF directional modulation technique using a switched antenna array for physical layer secure communication. The main idea is that a switching scheme of the switched antenna array is designed according to a spreading sequence for the purpose of spreading spectrum of the transmit signal. The transmit signal is associated with the spreading sequence and the direction of...

A novel 2-D composite right/left-handed transmission line (CRLH-TL) metamaterial in polar coordinates is proposed for the first time, and applied to a multistandard antenna. The prototype antenna with triband operation colocated pattern polarization diversity specifically designed eliminate need multiple antennas processing center side significantly reduce area cost. Radial CRLH-TL waves of mod...

Provision of energy to wireless sensor networks is crucial for their sustainable operation. Sensor nodes are typically equipped with batteries as their operating energy sources. However, when the sensor nodes are sited in almost inaccessible locations, replacing their batteries incurs high maintenance cost. Under such conditions, wireless charging of sensor nodes by a mobile charger with an ant...

Use of directional antenna in the context of ad hoc wireless networks can largely reduce radio interference, thereby improving the utilization of wireless medium. To achieve this, we have proposed an adaptive MAC protocol, where each node keeps certain neighborhood information dynamically so that each node can avoid interference by keeping track of other communicating nodes at that instant of t...

Modern day systems often require reconfigurability in the operating parameters of the transmit and receive antennas, such as the resonant frequency, radiation pattern, impedance, or polarization. In this work a novel approach to antenna reconfigurability is presented by integrating antennas with the ancient art of origami. The proposed antenna consists of an inkjet printed center-fed spiral ant...

Directional antennas have the potential to provide a fundamental breakthrough in ad hoc network capacity. Omni-directional nature of transmission restricts the network capacity, where distribution of energy in all directions other than the intended direction of the destination node not only generated unnecessary interference to other neighboring nodes but also decreases the potential range of t...

Ultra wideband (UWB) propagation is antenna-dependent, and multipath components experiencing specular diffraction or arriving at different angles have different shapes. To utilise the diversity of the multipath components, this study proposes a statistical model which incorporates directional parameters, such as elevation and azimuth angles by extending the IEEE802.15.3a model. Based on this mo...

As the demand for wireless networks grows, the research community continues to seek methods for improving network performance. On method for improving network throughput involves using directional antennas to increase signal gain and/or decrease interference. The physical-layer models used in current networking simulators only minimally address the interaction of directional antennas and radio ...