Abstract
This paper focuses on improved error control schemes for highspeed wireless digital communications. The main objective is a better quality support for real-time services, such as video, when using wireless mobile digital networks. In view of that, and besides the schemes already standardized, a novel error control mechanism is proposed. This new mechanism relies mainly in the use of Hybrid Automatic Repeat reQuest (HARQ) error control schemes and differentiated error robustness transmission modes. In this sense, when implementing this new technique, some of the capabilities offered by modem Wireless Local Area Networks (WLANs) are significantly better utilized. To make the performance analysis of the proposed error control mechanism, and corresponding comparison with existing systems, it was developed a system simulation environment, together with other computational tools. Analysis for diverse radio channel conditions, from AWGN modeling to Gilbert-Elliot modeling, has been done and some examples are subsequently presented. The simulation results show that this new strategy greatly improves the performance of real-time services, fulfilling the requirement of limited delays and enabling higher data rates.

Abstract

Abstract
We have studied the effect of gamma radiation on Long Period Fiber Grating (LPFG) temperature sensors fabricated in a pure-silica fiber, using the arc discharge technique. The temperature sensitivity of the LPFGs remains unchanged by the irradiation.

Abstract
Type S thermocouples were assembled in situ by applying high intensity electric are discharges to the contact junction of two platinum (Pt) and Pt-10% rhodium (Pt-10% Rh) wires, inserted on a silica capillary. The electrically insulated thermocouples built in this way were afterwards employed to estimate the temperature of an optical fiber subjected to arc discharges. For typical values of the arc discharge parameters used to arc-induce long-period fiber gratings (electric current I = 9 mA and arc duration t = 1 s), a capillary peak temperature value of 1420 degreesC +/- 400 degreesC was obtained by extrapolation of the experimental data for the limit situation of having a thermocouple with negligible diameter. The temperature profiles in the capillary and in an optical fiber were calculated based on a heat transfer model implemented by a finite element algorithm and fitted to the experimental temperature distribution in the Pt and Pt-10% Rh wires. The correspondent peak temperatures computed for the capillary and for the fiber were 1450 degreesC and 1320 degreesC, respectively. A good agreement between the capillary temperature values determined graphically and numerically was obtained.

Abstract
A dynamic dispersion compensation device using a chirped fibre Bragg grating with a ring geometry embedded in a composite laminated is proposed. A numerical model is presented and compared with the experimental setup. It is shown that the theoretical and experimental results are in good agreement. The tunability of the device is obtained by applying different radius of curvature to the ring structure, and thus producing non-linear variations in the spatial period of the chirped fibre Bragg grating, without changing the usable bandwidth.

Abstract
An intensity-referenced temperature-independent curvature measurement technique using a smart composite comprising two chirped fiber Bragg gratings is demonstrated. The two gratings are embedded on opposite sides of a composite laminate and act simultaneously as curvature sensors and as wavelength discriminators, enabling an unambiguous measurement of the composite radius of curvature.