Distributed Hybrid Two-Stage Multi-Sensor Fusion for Cooperative Modulation Classification in Large-Scale Wireless Sensor Networks.

Recent studies showed that the performance of the modulation classification (MC) is considerably improved by using multiple sensors deployed in a cooperative manner. Such cooperative MC solutions are based on the centralized fusion of independent features or decisions made at sensors. Essentially, the cooperative MC employs multiple uncorrelated observations of the unknown signal to gather more complete information, compared to the single sensor reception, which is used in the fusion process to refine the MC decision. However, the non-cooperative nature of MC inherently induces large loss in cooperative MC performance due to the unreliable measure of quality for the MC results obtained at individual sensors (which causes the partial information loss while performing centralized fusion). In this paper, the distributed two-stage fusion concept for the cooperative MC using multiple sensors is proposed. It is shown that the proposed distributed fusion, which combines feature (cumulant) fusion and decision fusion, facilitate preservation of information during the fusion process and thus considerably improve the MC performance. The clustered architecture is employed, with the influence of mismatched references restricted to the intra-cluster data fusion in the first stage. The adopted distributed concept represents a flexible and scalable solution that is suitable for implementation of large-scale networks.

Spectral analysis of intraocular pressure pulse wave in ocular hypertensive and primary open angle glaucoma patients.

CONTEXT: In attempt to find an alternative way to determine conversion from ocular hypertension to primary open angle glaucoma (POAG) (besides visual field and optic disc changes), we analyzed intraocular pressure (IOP) pulse wave in spectral domain. AIMS: The aim of this study was to test the potential differences in spectral content of IOP pulse wave between ocular hypertension and POAG patients, which could indicate conversion. SETTINGS AND DESIGN: Cross-sectional study designed to test the differences in the spectral content of pressure pulse wave between nontreated ocular hypertensive and nontreated, freshly diagnosed POAG patients. METHODS: The total of 40 eyes of 40 subjects was included: 20 previously untreated ocular hypertensive patients, and 20 previously untreated POAG patients. Continuous IOP measuring gained by dynamic contour tonometry was submitted to fast Fourier transform signal analysis and further statistical data processing. Statistics Analysis Used: Ocular and systemic characteristics of the tested subjects were compared by analysis of variance appropriate for this study design. A P < 0.05 was considered to be statistically significant. RESULTS: Higher spectral components of the IOP pulse wave was discerned up to the fifth harmonic in both of the tested groups. No statistically significant differences were found in any of the tested harmonic amplitudes. CONCLUSIONS: There are no differences in the spectral content of IOP pulse wave between ocular hypertensive and primary open angle glaucoma patients which could be indicative for conversion.

Spectral analysis of intraocular pressure pulse wave in open angle glaucomas and healthy eyes.

PURPOSE: To investigate the spectral content of intraocular pressure (IOP) pulse wave by advanced spectral signal processing of continuous IOP readings obtained by dynamic contour tonometry. PATIENTS AND METHODS: A non-interventional case-control study included 20 healthy subjects, 20 previously untreated primary open angle glaucoma patients, and 20 previously untreated normal tension glaucoma patients. The continuous IOP reading obtained by dynamic contour tonometry was submitted to Fast Fourier Transform signal analysis and further statistical data processing. RESULTS: The spectral components of the IOP pulse wave were discerned up to the fifth harmonic. Highly statistically significant difference was found between the control group and the primary open angle group, and between the primary open angle glaucoma group and the normal tension glaucoma group in the first, second and the third harmonic amplitude (p < 0.01). Glaucoma patients had significantly higher ocular pulse volume values. CONCLUSIONS: It is possible to determine spectral components of the IOP pulse wave up to the fifth harmonic by a spectral analysis of dynamic contour tonometry continuous readings. We found that high Ocular Pulse Amplitude values in primary open angle glaucoma group was associated with high harmonics amplitude, which indicates low rigidity of blood vessels.