Information and System Group

May 2013

No Date Title Speaker Presentation Discussion
1 2013-05-09  Turbo Reconstruction of Structured Sparse Signal Hyeongho   pdf  
This paper considers the reconstruction of structured-sparse signals from noisy linear observations. In particular, the support of the signal coefficients is parameterized by hidden binary pattern, and a structured probabilistic prior (e.g., Markov random chain/field/tree) is assumed on the pattern. Exact inference is discussed and an approximate inference scheme, based on loopy belief propagation (BP), is proposed. The proposed scheme iterates between exploitation of the observation-structure and exploitation of the pattern-structure, and is closely related to noncoherent turbo equalization, as used in digital communication receivers. An algorithm that exploits the observation structure is then detailed based on approximate message passing ideas.
2 2013-05-16 Compressive fluorescence microscopy for biological hyperspectral imaging Eunseok PDF
 The mathematical theory of compressed sensing (CS) asserts that one can acquire signals from measurements whose rate is much lower than the total bandwidth. Whereas the CS theory is now well developed, challenges concerning hardware implementations of CS-based acquisition devices—especially in optics—have only started being addressed. This paper presents an implementation of compressive sensing in fluorescence microscopy and its applications to biomedical imaging. Our CS microscope combines a dynamic structured wide-field illumination and a fast and sensitive single-point fluorescence detection to enable reconstructions of images of fluorescent beads, cells, and tissues with undersampling ratios (between the number of pixels and number of measurements) up to 32. We further demonstrate a hyperspectral mode and record images with 128 spectral channels and undersampling ratios up to 64, illustrating the potential benefits of CS acquisition for higher-dimensional signals, which typically exhibits extreme redundancy. Altogether, our results emphasize the interest of CS schemes for acquisition at a significantly reduced rate and point to some remaining challenges for CS fluorescence microscopy.
3 2013-05-30  Simplified Relay Selection and Power Allocation in Cooperative Cognitive Radio Systems Muhammad Asif  PDF
 In this paper authors propose solution of a combined problem; relay selection and power allocation to secondary users under the constraint of limited interference to primary users in cognitive radio (CR) system. Objective of the joint problem was to maximize system throughput. A high complexity optimal solution and a low complexity suboptimal solution are proposed. The presented solutions show over 50% improvement in system throughput.