Abstract
The growth of available broadband access technologies has brought an enormous challenge for operators wanting to ensure seamless mobility to its customers in heterogeneous environments. In this paper we present an enhanced Mobility Management entity focused on a real heterogeneous environments and based on IEEE802.21 standard. This entity is capable to perform terminal and handover management regardless the access technology used. This entity was deployed in a real heterogeneous environment with Wi-Fi, WiMAX and HSPA using an Android smartphone. In order to provide Layer 3 mobility support it was integrated with a modified version of MIPv6. The results show not only the impact of a centralized entity to manage vertical handovers, but also the performance of IEEE802.21 protocol in a real scenario with a real implementation. ©2011 IEEE © 2011 IEEE.© 2011 IEEE.

Abstract
Explicit congestion control (XCC) is emerging as one potential solution for overcoming limitations inherent to the current TCP algorithm, characterized by unstable throughput, high queuing delay, RTT-limited fairness, and a static dynamic range that does not scale well to high bandwidth delay product networks. In XCC, routers provide multibit feedback to sources, which, in turn, adapt throughput more accurately to the path bandwidth with potentially faster convergence times. Such systems, however, require precise knowledge of link capacity for efficient operation. In the presence of variable-capacity media, e.g., 802.11, such information is not entirely obvious or may be difficult to extract. We explore three possible algorithms for XCC which retain efficiency under such conditions by inferring available bandwidth from queue dynamics and test them through simulations with two relevant XCC protocols: XCP and RCP. Additionally, preliminary results from an experimental implementation based on XCP are presented. Finally, we compare our proposals with TCP and show how such algorithms outperform it in terms of efficiency, stability, queuing delay, and flow-rate fairness.

Abstract
Wireless Sensor Networks (WSNs) for medical purposes enables real-time (RT) acquisition of vital signals. In this context the network reliability, data integrity and RT delivery have extreme importance. The network should guarantee an appropriate level of Quality of Service (QoS). This paper presents the QoS parameters and metrics of standard telemedicine and WSNs based Medical Applications (MA), and a strategy, based on QoS monitoring, to prevent QoS degradation in WSNs for MA.

Abstract

Abstract
The evaluation of elementary functions can be performed by approximations using minimax polynomials requiring simple hardware resources. The general method to calculate an elementary function is composed by three steps: range reduction, computation of the polynomial in the reduced argument and range reconstruction. This approach allows a low-degree polynomial approximation but range reduction and reconstruction introduce a computation overhead. This work proposes an evaluation methodology without range reduction and range reconstruction steps. Applications that need to compute elementary functions may benefit from avoiding these steps if the argument belongs to a sub-domain of the function. Particularly in the context of embedded systems, applications related to digital signal processing most of the times require function evaluation within a specific interval. As a consequence of not doing range reduction, the degree of the approximant polynomials increases to maintain the required precision. Interval segmentation is an effective way to overcome this issue because the approximations are computed in smaller intervals. The proposed methodology uses non-uniform segmentation as a way to mitigate the problem arising from not carrying out range reduction. The benefits that come from applying interval segmentation to the general evaluation technique are limited by the range reduction and reconstruction steps because the segmentation only applies to the approximation step. However, when used in the proposed methodology it reveals more effective. Some elementary functions were implemented using the proposed methodology in a FPGA device. The metric used to characterize the proposed technique are the area occupation and the corresponding latency. The results of each implementation without range reduction were compared with the corresponding ones of the general method using range reduction. The results show that latency can be significantly reduced while the area is approximately the same.

Abstract
Different built-in self testing schemes for RF circuits have been developed resorting to peak voltage detectors. These are simple to implement but provide a conditional RF power measurement accuracy as impedance is assumed to be known. A true power detector is presented which allows obtaining more accurate measurements, namely as far as output load variations are concerned. The theoretical fundaments underlining the power detector operating principle are presented and simulation and experimental results obtained with a prototype chip are described which confirm the benefits of measuring true power, comparing to output peak voltage, when observing output load matching deviations and complex waveforms.