Catálogo de publicaciones - libros

This paper presents the design and implementation of an indoor surveillance Wireless Sensor Network (WSN) using tools for hastening and facilitating the different phases in the WSN development. First, the application case is described in WISENES (WIreless SEnsor NEtwork Simulator) framework by four models, which define application, communication, node, and environment. WISENES enables a graphical design of the models combined with accurate simulations for performance evaluation. Next, surveillance application tasks and communication protocols are implemented on node platforms on top of SensorOS Operating System (OS). A congruent programming model of SensorOS allows a straightforward mapping of WISENES models to the final implementation. The evaluation of the indoor surveillance WSN implemented with Tampere University of Technology WSN (TUTWSN) protocols and platforms reaches a lifetime in order of years while still ensuring reactive operation. Further, the results show only 9.5 % and 6.6 % differences in simulated and measured networking delay and power consumption, respectively. Our results indicate that accurate early design phase simulations can relieve the burden of prototyping and low level implementation by a realistic configuration evaluation during design time.

This paper presents a method for system architecture modeling of an IR-UWB (Impulse Radio Ultra WideBand) receiver for sensors networks applications. We expose the way for designing an FPGA (Field Programmable Gate Array) receiver starting from a previous study based on system modeling on Matlab. The proposed receiver architecture is first designed and validated on Matlab, before being implemented, thanks to VHDL language, on a FPGA. Our study shows the interest and the advantages of co-design Matlab-VHDL. We will propose here different IR-UWB receiver architecture depending on the modulation used. We will also introduce in this paper a data-rate and TH-code reconfigurable receiver. Using co-simulation Matlab-VHDL, we have compared three kind of IR-UWB receiver: TH-PPM, TH-OOK, TH-BPAM, with respect to BER/SNR criteria and in the specific context of wireless sensors networks, at high level (Matlab) and hardware level (FPGA-Xilinx).

Wireless sensor nodes are increasingly being tasked with computation and communication intensive functions while still subject to constraints related to energy availability. On these embedded platforms, once all low power design techniques have been explored, duty-cycling the various subsystems remains the primary option to meet the energy and power constraints. This requires the ability to provide spurts of high MIPS and high bandwidth connections. However, due to the large overheads associated with duty-cycling the computation and communication subsystems, existing high performance sensor platforms are not efficient in supporting such an option. In this paper, we present the design and optimizations taken in a wireless gateway node (WGN) that bridges data from wireless sensor networks to Wi-Fi networks in an on-demand basis. We discuss our strategies to reduce duty-cycling related costs by partitioning the system and by reducing the amount of time required to activate or deactivate the high-powered components. We compare the design choices and performance parameters with those made in the Intel platform to show the effectiveness of duty-cycling on our platform. We have built a working prototype, and the experimental results with two different power management schemes show significant reductions in latency and average power consumption compared to the .

This paper presents design and implementation of a multi-threading Operating System (OS), SensorOS, for resource constrained Wireless Sensor Network (WSN) nodes. Compared to event-handler kernels, such as TinyOS, SensorOS enables coexistence of multiple time critical application tasks. SensorOS supports preemptive priority-based scheduling, very fine-granularity timing, and message passing inter-process communication. SensorOS has been implemented for resource constrained Tampere University of Technology WSN (TUTWSN) nodes. In TUTWSN node platform with 2 MIPS PIC micro-controller unit, SensorOS kernel uses 6964 B code and 115 B data memory. The context swap time is 92 s and the variance of timing accuracy for a high priority thread less than 5 s. The results show that the realtime coordination of WSN applications and protocols can be managed by a versatile OS even on resource constrained nodes.

Wireless Sensor Networks (WSN) are seen as attractive solutions for various monitoring and controlling applications, a large part of which require cryptographic protection. Due to the strict cost and power consumption requirements, their cryptographic implementations should be compact and energy-efficient. In this paper, we survey hardware architectures proposed for Advanced Encryption Standard (AES) implementations in low-cost and low-power devices. The survey considers both dedicated hardware and specialized processor designs. According to our review, currently 8-bit dedicated hardware designs seem to be the most feasible solutions for embedded, low-power WSN nodes. Alternatively, compact special functional units can be used for extending the instruction sets of WSN node processors for efficient AES execution.

For most applications in wireless sensor networks (WSNs), it is often assumed that the deployment of sensor nodes is unmanaged and random, so the density of local node may vary throughout the network. In high density areas, nodes consume more energy due to frequent packet collisions and retransmissions. One of the ways to alleviate this problem is to adjust the transmission power of each sensor node by means of efficient topology control mechanisms. In this paper, we propose an efficient topology control for energy conservation, named “k+ Neigh.” In our scheme, each sensor node reduces its transmission power so that it has minimum number of k neighbor nodes. Later, we will show that the preferred value of the k is 2 by simulation. In the performance evaluation, the proposed scheme can make significant energy saving with such a topology structure, while the network connectivity is guaranteed.