Error Rate Analysis for Coded Multicarrier Systems over Quasi-Static Fading Channels

This paper presents two methods for approximating the performance of coded multicarrier systems operating over frequency-selective, quasi-static fading channels with non-ideal interleaving. The first method is based on approximating the performance of the system over each realization of the channel, and is suitable for obtaining the outage performance of this type of system. The second method is based on knowledge of the correlation matrix of the frequency-domain channel gains and can be used to directly obtain the average performance. Both of the methods are applicable for convolutionally-coded interleaved systems employing Quadrature Amplitude Modulation (QAM). As examples, both methods are used to study the performance of the Multiband Orthogonal Frequency Division Multiplexing (OFDM) proposal for high data-rate Ultra-Wideband (UWB) communication.Comment: 5 pages, 3 figures, 2 tables. Submitted to Globecom 200

Performance Analysis and Enhancement of Multiband OFDM for UWB Communications

In this paper, we analyze the frequency-hopping orthogonal frequency-division multiplexing (OFDM) system known as Multiband OFDM for high-rate wireless personal area networks (WPANs) based on ultra-wideband (UWB) transmission. Besides considering the standard, we also propose and study system performance enhancements through the application of Turbo and Repeat-Accumulate (RA) codes, as well as OFDM bit-loading. Our methodology consists of (a) a study of the channel model developed under IEEE 802.15 for UWB from a frequency-domain perspective suited for OFDM transmission, (b) development and quantification of appropriate information-theoretic performance measures, (c) comparison of these measures with simulation results for the Multiband OFDM standard proposal as well as our proposed extensions, and (d) the consideration of the influence of practical, imperfect channel estimation on the performance. We find that the current Multiband OFDM standard sufficiently exploits the frequency selectivity of the UWB channel, and that the system performs in the vicinity of the channel cutoff rate. Turbo codes and a reduced-complexity clustered bit-loading algorithm improve the system power efficiency by over 6 dB at a data rate of 480 Mbps.Comment: 32 pages, 10 figures, 1 table. Submitted to the IEEE Transactions on Wireless Communications (Sep. 28, 2005). Minor revisions based on reviewers' comments (June 23, 2006

Spanish housing markets during the first phase of the rural-urban transition process

This paper discusses how Spain’s housing markets reacted to the far-reaching changes that affected the demand for dwellings during the first phase of the rural-urban transition process. To this end, we construct a new hedonic index of real housing prices and assemble a cross-regional panel dataset of price fundamentals. The results of our econometric analysis suggest that housing markets did not face supply constraints, responded swiftly to the growing demand for accommodation and were efficient. In light of this new evidence, we conclude that housing markets were not a burden for Spanish economic development and that Spain’s institutional and regulatory frameworks were suitable for the housing needs at the time.Hedonic prices, Demand and supply of housing, Regulation in housing markets

Cosmological Implications of the Tetron Model of Elementary Particles

Based on a possible solution to the tetron spin problem, a modification of the standard Big Bang scenario is suggested, where the advent of a spacetime manifold is connected to the appearance of tetronic bound states. The metric tensor is constructed from tetron constituents and the reason for cosmic inflation is elucidated. Furthermore, there are natural dark matter candidates in the tetron model. The ratio of ordinary to dark matter in the universe is calculated to be 1:5.Comment: 23 page

A Victimless Sex Crime: The Case for Decriminalizing Consensual Teen Sexting

As teenagers\u27 access to cellular phones and the internet has increased over the past two decades, so has their ability to harm themselves and others through misuse of new technology. One risky behavior that has become common among teenagers is sexting --the digital sharing of sexually suggestive images. To combat the dangers of teen sexting, many states have criminalized the act. Criminalization does not resolve the issue of teen sexting, however, and in many cases it may cause additional harm. This Note reviews existing state laws related to teen sexting, and critiques these laws on constitutional and policy grounds. It then proposes a model statute to decriminalize consensual teen sexting

Investigation of charge coupled device correlation techniques

Analog Charge Transfer Devices (CTD's) offer unique advantages to signal processing systems, which often have large development costs, making it desirable to define those devices which can be developed for general system's use. Such devices are best identified and developed early to give system's designers some interchangeable subsystem blocks, not requiring additional individual development for each new signal processing system. The objective of this work is to describe a discrete analog signal processing device with a reasonably broad system use and to implement its design, fabrication, and testing

Resolving Small Business Disputes Through Mediation

A revolution is taking place  in the way Americans resolve their disputes. The so-called alternative methods of dispute resolution such as mediation and arbitration are increasingly becoming a primary choice for settling  conflict. A growing number of large American companies have begun to embrace mediation as an alternative to litigation. The article describes  the  mediation  process  in  the  small  business  context.  The  advantages   and disadvantages of mediation versus the judicial process are considered. Recommendations concerning the appropriate circumstances in which small business should use mediation to resolve conflict are provided. Also reported are the results of a survey of small business executives that measured their attitudes toward mediation and other forms of dispute resolution. The results suggest that most executives preferred mediation to other forms of dispute resolution. They believe mediation to be a cost-effective and efficient method of resolving conflicts with customers, employees, and suppliers