Abstract
Narrow band parametric speech coding and wideband audio coding represent opposite coding paradigms involving audible information, namely in terms of the specificity of the audio material, target bit rates, audio quality and application scenarios. In this paper we explore a new avenue addressing parametric coding of wideband speech, using the potential and accuracy provided by frequency-domain signal analysis and modeling techniques that typically belong to the realm of high-quality audio coding. A first analysis-synthesis validation framework is described that illustrates the decomposition, parametric representation and synthesis of perceptually and linguistically relevant speech components while preserving naturalness and speaker specific information.

Abstract
Real-time monitoring applications may generate delay sensitive traffic that is expected to be delivered within a firm delay boundary in order to be useful. In this context, a previous work proposed an End-to-End Delay (EED) estimation mechanism for Wireless Sensor Networks (WSNs) to preview potential useless packets, and to early discard them in order to save processing and energy resources. Such estimation mechanism accounts delays using timers that make use of an Exponentially Weighted Moving Average (EWMA) function where the smoothing factor is a constant defined prior to the WSN deployment. Later experiments showed that, in order to enhance the estimation results, such smoothing factor should be defined as a function of the network load. The current work proposes an optimization of the previous estimation mechanism that works by evaluating the network load and by adapting the smoothing factor of the EWMA function accordingly. Results show that this optimization leads to a more accurate EED estimation for different network loads.

Abstract
Radio Frequency (RF) communications su.er high attenuation underwater, limiting the range of standard IEEE 802.11 networks to a few centimeters underwater. The usage of custom RF solutions at lower frequencies to increase range entails high development costs, and proprietary hardware. This paper evaluates the performance of cost-e.ective, mass-market IEEE 802.11 networks underwater at di.erent frequencies in the sub-GHz bands using Software Defined Radio platforms. Optimizations to the gr-ieee802.11 implementation, together with custom designed antennas, allowed the testing of frequencies in the 70-700 MHz range, in a large-scale freshwater tank, and in real-world, seawater conditions in Tagus river estuary. Results show a frequency-dependent communications range up to 5 m in freshwater and 1.8 m in seawater, with bitrates up to 550 kbit/s and delay under 45 ms. This proves the feasibility of IEEE 802.11 networks in the sub-GHz bands for applications such as video streaming from an autonomous underwater vehicle and underwater sensors. Copyright 2015 ACM.

Abstract
The demand for broadband underwater communications is being pushed by the increasing use of Autonomous Underwater Vehicles (AUV) in underwater missions. IEEE 802.11, already used in AUV for above water communications, can also be employed underwater to enable cost-effective, high bandwidth, short range communications. However, the high RF attenuation underwater induces high variations of received power, which may affect the performance of existing rate adaptation algorithms designed for over-the-air networks. This paper evaluates the most relevant state-of-the-art IEEE 802.11 rate adaptation algorithms in underwater environment. Simulation results show the AARF algorithm outperforms the widely used Minstrel algorithm, as well as the CARA, RRAA and ONOE algorithms. Copyright 2015 ACM.

Abstract
Wireless Underground Networks (WUNs) have applications such as agriculture, border surveillance, maintenance of playing fields, and infrastructure monitoring. When designing a sensor network for one of these applications some of the sensors (communication nodes) will be buried underground, which means the propagation medium will be the soil or hybrid (air plus soil) in case of one of the nodes is aboveground. Thus, new models have to be implemented in existing simulators, in order to enable the proper simulation of these communications scenarios. This paper presents a new model, named underground model, and discusses its integration into the NS-3 simulator. The underground model enables the simulation of WUNs, including network topologies with underground and aboveground nodes. The accuracy of the underground model is shown for two frequency bands by comparing simulations results with experimental results. © 2015 ACM.

Abstract
Wireless Sensor Networks (WSNs) can be deployed using available hardware and software. The Contiki is an operative system compatible with a wide range of WSN hardware. A Contiki development environment named InstantContiki is also available and includes the Cooja simulator, useful to test WSN simulation scenarios prior to their deployment. Cooja can provide realistic results since it uses the full Contiki's source code and some motes can be emulated at the hardware level. However this implies extending the simulation runtime, which is heightened since the Cooja is single threaded, i.e, it makes use of a single core per instant of time, not taking advantage of the current multi-core processors. This chapter presents a framework to automate the configuration and execution of Cooja simulations. When a multi-core processor is available, this framework runs multiple simultaneous Cooja instances to reduce simulations runtime in exchange of higher CPU load and RAM usage.