CA-CFAR Detection Based on an AWG Interference Model in a Low-Complexity WCP-OFDM Receiver

In this paper, we consider a previously described low-complexity WCP-OFDM radar receiver and focus on the self-interference component induced by targets throughout this processing. Particularly, we assume and verify by simulation that this self-interference can be modeled in the range-Doppler map as an additive white Gaussian process independent from the internal noise. To that end, we propose an expression for the signal-to-interference-plus-noise ratio and verify by simulation that the expected performance of the well-known CA-CFAR detector are recovered and thus predictable

Comparison of Correlation-Based OFDM Radar Receivers

Various correlation-based receivers have been proposed in passive bistatic and active monostatic radar exploiting information-bearing orthogonal frequency-division multiplexing (OFDM) transmissions, but too little has been dedicated to establishing their relations and advantages over each other. Accordingly, this paper provides an analytical comparison of the most commonly encountered filters, along with a performance analysis regarding three criteria: computational complexity, signal-to-interference-plus-noise-ratio and resilience to ground clutter. The last two especially assess the possible detrimental effects of the random sidelobes (or pedestal) induced by the data symbols in the range-Doppler map. Although simulations show that none of the filters performs unanimously better, the ones employing circular correlations globally evidence attractive results

The effects of room design on computer-supported collaborative learning in a multi-touch classroom.

While research indicates that technology can be useful for supporting learning and collaboration, there is still relatively little uptake or widespread implementation of these technologies in classrooms. In this paper, we explore one aspect of the development of a multi-touch classroom, looking at two different designs of the classroom environment to explore how classroom layout may influence group interaction and learning. Three classes of students working in groups of four were taught in the traditional forward-facing room condition, while three classes worked in a centered room condition. Our results indicate that while the outcomes on tasks were similar across conditions, groups engaged in more talk (but not more off-task talk) in a centered room layout, than in a traditional forward-facing room. These results suggest that the use of technology in the classroom may be influenced by the location of the technology, both in terms of the learning outcomes and the interaction behaviors of students. The findings highlight the importance of considering the learning environment when designing technology to support learning, and ensuring that integration of technology into formal learning environments is done with attention to how the technology may disrupt, or contribute to, the classroom interaction practices

The Four Ts of the Collaborative Classroom

Abstract: Drawing on a multi-year study of using multi-touch tables in a classroom setting, this paper lays out a framework to use when designing and studying collaborative classrooms. The framework identified the overlapping aspects of teachers, tasks, technology and teams, as being essential features of the use of computer-supported collaborative learning in classrooms. We argue that the design of collaborative classrooms should take this model into account during design and evaluation phases. This paper contributes to the Methods and Techniques strand of the Orchestrated Collaborative Classrooms Workshop

Successive Self-Interference Cancellation in a Low-Complexity WCP-OFDM Radar Receiver

In this paper, we consider a multicarrier waveform to perform simultaneously data transmission and radar sensing. On the radar receiver side, a state-of-the-art symbol-based algorithm generates a range-Doppler map affected by a self-interference phenomenon, potentially leading to target masking issues. Herein, we propose a successive interference cancellation procedure to enhance the radar performance while keeping a low-complexity implementation. We show that a very low reconstruction error is obtained in various scenarios. We also investigate the robustness of the proposed algorithm since it is subject to error propagation

Study of the Target Self-Interference in a Low-Complexity OFDM-Based Radar Receiver

This paper investigates a radar-communications waveform sharing scenario. Particularly, it addresses the selfinterference phenomenon induced by independent single-point scatterers throughout a low-complexity monostatic OFDM-based radar receiver from a statistical viewpoint. Accordingly, an analytical expression of the post-processing signal-to-interferenceplus-noise-ratio is derived and detection performance is quantified in simulated scenarios for rectangular and non-rectangular pulses. Both metrics suggest that this phenomenon must be further handled

Target Sidelobes Removal via Sparse Recovery in the Subband Domain of an OFDM RadCom System

In this paper, the problem of target masking induced by sidelobes arising in an OFDM RadCom System is considered. To fully exploit the waveform structure and address practical scenarios, we propose to deal with the sidelobes in the subband domain via sparse recovery. Accordingly, we design a sparsifying dictionary modeling at the same time the target's peak and pedestal. Results on synthetic data show that our approach allows one to remove not only the target random sidelobes but also range ambiguities arising when all subbands are not active

Clairvoyant Clutter Mitigation in a Symbol-Based OFDM Radar Receiver

This paper investigates clutter rejection techniques in an OFDM symbol-based radar receiver. Two rejection filters that assume known the clutter covariance matrix are proposed. These aim at mitigating not only the clutter main peak but also its noise-like pedestal that leads to target masking issues. Performance is assessed with synthetic data on filters outputs and in terms of signal-to-clutter-plus-noise-ratio. Results show that the proposed methods succeed, to some extent, in uncovering exo-clutter targets. Rejecting clutter within the symbol-based architecture (instead of prior to) is advantageous for slowly-moving targets

Correlation-Based Radar Receivers with Pulse-Shaped OFDM Signals

In waveform sharing scenarios, various radar receivers have been developed for orthogonal frequency-division multiplexing (OFDM) signals. More general waveforms, such as pulse-shaped multicarrier modulations received little attention so far, despite their increased robustness to high-Doppler scatterers. In this paper, we compare the performance of two correlation-based radar receivers, namely the matched filter and the symbol-based technique, when used with different pulse-shaped multicarrier waveforms. We express the signal-to-interference-plus-noise-ratio in the range-Doppler map, taking into account the pedestal (or random sidelobes) induced by the symbols. Benefits of pulse shaping is further illustrated in a realistic vehicular scenario, in presence of multiple targets and ground clutter. In this context, the symbol-based approach outperforms the matched filter while enjoying a low-computational complexity. More generally, our results reveal the multicarrier pulse shape as a relevant degree of freedom in waveform co-design approaches (e.g., cognitive radar/communication systems)

A filtered database search algorithm for endogenous serum protein carbonyl modifications in a mouse model of inflammation

During inflammation, the resulting oxidative stress can damage surrounding host tissue, forming protein-carbonyls. The SJL mouse is an experimental animal model used to assess in vivo toxicological responses to reactive oxygen and nitrogen species from inflammation. The goals of this study were to identify the major serum proteins modified with a carbonyl functionality and to identify the types of carbonyl adducts. To select for carbonyl-modified proteins, serum proteins were reacted with an aldehyde reactive probe that biotinylated the carbonyl modification. Modified proteins were enriched by avidin affinity and identified by two-dimensional liquid chromatography tandem MS. To identify the carbonyl modification, tryptic peptides from serum proteins were subjected to avidin affinity and the enriched modified peptides were analyzed by liquid chromatography tandem MS. It was noted that the aldehyde reactive probe tag created tag-specific fragment ions and neutral losses, and these extra features in the mass spectra inhibited identification of the modified peptides by database searching. To enhance the identification of carbonyl-modified peptides, a program was written that used the tag-specific fragment ions as a fingerprint (in silico filter program) and filtered the mass spectrometry data to highlight only modified peptides. A de novo-like database search algorithm was written (biotin peptide identification program) to identify the carbonyl-modified peptides. Although written specifically for our experiments, this software can be adapted to other modification and enrichment systems. Using these routines, a number of lipid peroxidation-derived protein carbonyls and direct side-chain oxidation proteins carbonyls were identified in SJL mouse serum.National Institutes of Health (U.S.) (NCI Program Project Grant CA26731)Massachusetts Institute of Technology. Center for Environmental Health Sciences (NIEHS grant P30 ES002109