Maximum-rate Transmission with Improved Diversity Gain for Interference Networks

Interference alignment (IA) was shown effective for interference management to improve transmission rate in terms of the degree of freedom (DoF) gain. On the other hand, orthogonal space-time block codes (STBCs) were widely used in point-to-point multi-antenna channels to enhance transmission reliability in terms of the diversity gain. In this paper, we connect these two ideas, i.e., IA and space-time block coding, to improve the designs of alignment precoders for multi-user networks. Specifically, we consider the use of Alamouti codes for IA because of its rate-one transmission and achievability of full diversity in point-to-point systems. The Alamouti codes protect the desired link by introducing orthogonality between the two symbols in one Alamouti codeword, and create alignment at the interfering receiver. We show that the proposed alignment methods can maintain the maximum DoF gain and improve the ergodic mutual information in the long-term regime, while increasing the diversity gain to 2 in the short-term regime. The presented examples of interference networks have two antennas at each node and include the two-user X channel, the interferring multi-access channel (IMAC), and the interferring broadcast channel (IBC).Comment: submitted to IEEE Transactions on Information Theor

Frequency diversity wideband digital receiver and signal processor for solid-state dual-polarimetric weather radars

2012 Summer.Includes bibliographical references.The recent spate in the use of solid-state transmitters for weather radar systems has unexceptionably revolutionized the research in meteorology. The solid-state transmitters allow transmission of low peak powers without losing the radar range resolution by allowing the use of pulse compression waveforms. In this research, a novel frequency-diversity wideband waveform is proposed and realized to extenuate the low sensitivity of solid-state radars and mitigate the blind range problem tied with the longer pulse compression waveforms. The latest developments in the computing landscape have permitted the design of wideband digital receivers which can process this novel waveform on Field Programmable Gate Array (FPGA) chips. In terms of signal processing, wideband systems are generally characterized by the fact that the bandwidth of the signal of interest is comparable to the sampled bandwidth; that is, a band of frequencies must be selected and filtered out from a comparable spectral window in which the signal might occur. The development of such a wideband digital receiver opens a window for exciting research opportunities for improved estimation of precipitation measurements for higher frequency systems such as X, Ku and Ka bands, satellite-borne radars and other solid-state ground-based radars. This research describes various unique challenges associated with the design of a multi-channel wideband receiver. The receiver consists of twelve channels which simultaneously downconvert and filter the digitized intermediate-frequency (IF) signal for radar data processing. The product processing for the multi-channel digital receiver mandates a software and network architecture which provides for generating and archiving a single meteorological product profile culled from multi-pulse profiles at an increased data date. The multi-channel digital receiver also continuously samples the transmit pulse for calibration of radar receiver gain and transmit power. The multi-channel digital receiver has been successfully deployed as a key component in the recently developed National Aeronautical and Space Administration (NASA) Global Precipitation Measurement (GPM) Dual-Frequency Dual-Polarization Doppler Radar (D3R). The D3R is the principal ground validation instrument for the precipitation measurements of the Dual Precipitation Radar (DPR) onboard the GPM Core Observatory satellite scheduled for launch in 2014. The D3R system employs two broadly separated frequencies at Ku- and Ka-bands that together make measurements for precipitation types which need higher sensitivity such as light rain, drizzle and snow. This research describes unique design space to configure the digital receiver for D3R at several processing levels. At length, this research presents analysis and results obtained by employing the multi-carrier waveforms for D3R during the 2012 GPM Cold-Season Precipitation Experiment (GCPEx) campaign in Canada

New Aspects of Progress in the Modernization of the Maritime Radio Direction Finders (RDF)

This paper as an author contribution introduces the implementation of the new aspects in the modernization of the ships Radio Direction Finders (RDF) and their modern principles and applications for shipborne and coastal navigation surveillance systems. The origin RDF receivers with the antenna installed onboard ships or aircraft were designed to identify radio sources that provide bearing the Direction Finding (DF) signals. The radio DF system or sometimes simply known as the DF technique is de facto a basic principle of measuring the direction of signals for determination of the ship\u27s position. The position of a particular ship in coastal navigation can be obtained by two or more measurements of certain radio sources received from different unspecified locations of transmitters on the coast. In the past, the RDF devices were widely used as a radio navigation system for aircraft, vehicles, and ships in particular. However, the newly developed RDF devices can be used today as an alternative to the Radio – Automatic Identification System (R-AIS), Satellite – Automatic Identification System (S-AIS), Long Range Identification and Tracking (LRIT), radars, GNSS receivers, and another current tracking and positioning systems of ships. The development of a modern shipborne RDF for new positioning and surveillance applications, such as Search and Rescue (SAR), Man over board (MOB), ships navigation and collision avoidance, offshore applications, detection of research buoys and for costal vessels traffic control and management is described in this paper

New Aspects of Progress in the Modernization of the Maritime Radio Direction Finders (RDF)

This paper as an author contribution introduces the implementation of the new aspects in the modernization of the ships Radio Direction Finders (RDF) and their modern principles and applications for shipborne and coastal navigation surveillance systems. The origin RDF receivers with the antenna installed onboard ships or aircraft were designed to identify radio sources that provide bearing the Direction Finding (DF) signals. The radio DF system or sometimes simply known as the DF technique is de facto a basic principle of measuring the direction of signals for determination of the ship\u27s position. The position of a particular ship in coastal navigation can be obtained by two or more measurements of certain radio sources received from different unspecified locations of transmitters on the coast. In the past, the RDF devices were widely used as a radio navigation system for aircraft, vehicles, and ships in particular. However, the newly developed RDF devices can be used today as an alternative to the Radio – Automatic Identification System (R-AIS), Satellite – Automatic Identification System (S-AIS), Long Range Identification and Tracking (LRIT), radars, GNSS receivers, and another current tracking and positioning systems of ships. The development of a modern shipborne RDF for new positioning and surveillance applications, such as Search and Rescue (SAR), Man over board (MOB), ships navigation and collision avoidance, offshore applications, detection of research buoys and for costal vessels traffic control and management is described in this paper

Wireless-Powered Communication Assisted by Two-Way Relay with Interference Alignment Underlaying Cognitive Radio Network

This study investigates the outage performance of an under-laying wireless-powered secondary system that reuses the primary users (PU) spectrum in a multiple-input multiple-output (MIMO) cognitive radio (CR) network. Each secondary user (SU) harvests energy and receives information simultaneously by applying power splitting (PS) protocol. The communication between SUs is aided by a two-way (TW) decode and forward (DF) relay. We formulate a problem to design the PS ratios at SUs, the power control factor at the secondary relay, and beamforming matrices at all nodes to minimize the secondary network's outage probability. To address this problem, we propose a two-step solution. The first step establishes closedform expressions for the PS ratios at each SU and secondary relay's power control factor. Furthermore, in the second step, interference alignment (IA) is used to design proper precoding and decoding matrices for managing the interference between secondary and primary networks. We choose IA matrices based on the minimum mean square error (MMSE) iterative algorithm. The simulation results demonstrate a significant decrease in the outage probability for the proposed scheme compared to the benchmark schemes, with an average reduction of more than two orders of magnitude achieved

The Goldstone solar system radar: A science instrument for planetary research

The Goldstone Solar System Radar (GSSR) station at NASA's Deep Space Communications Complex in California's Mojave Desert is described. A short chronological account of the GSSR's technical development and scientific discoveries is given. This is followed by a basic discussion of how information is derived from the radar echo and how the raw information can be used to increase understanding of the solar system. A moderately detailed description of the radar system is given, and the engineering performance of the radar is discussed. The operating characteristics of the Arcibo Observatory in Puerto Rico are briefly described and compared with those of the GSSR. Planned and in-process improvements to the existing radar, as well as the performance of a hypothetical 128-m diameter antenna radar station, are described. A comprehensive bibliography of referred scientific and engineering articles presenting results that depended on data gathered by the instrument is provided

The Search for Extraterrestrial Intelligence (SETI)

A bibliography of reports concerning the Search for Extraterrestrial Intelligence is presented. Cosmic evolution, space communication, and technological advances are discussed along with search strategies and search systems