The Stochastic Shortest Path Problem : A polyhedral combinatorics perspective

In this paper, we give a new framework for the stochastic shortest path problem in finite state and action spaces. Our framework generalizes both the frameworks proposed by Bertsekas and Tsitsikli and by Bertsekas and Yu. We prove that the problem is well-defined and (weakly) polynomial when (i) there is a way to reach the target state from any initial state and (ii) there is no transition cycle of negative costs (a generalization of negative cost cycles). These assumptions generalize the standard assumptions for the deterministic shortest path problem and our framework encapsulates the latter problem (in contrast with prior works). In this new setting, we can show that (a) one can restrict to deterministic and stationary policies, (b) the problem is still (weakly) polynomial through linear programming, (c) Value Iteration and Policy Iteration converge, and (d) we can extend Dijkstra's algorithm

Enhancing PGA Tour Performance: Leveraging ShotlinkTM Data for Optimization and Prediction

In this study, we demonstrate how data from the PGA Tour, combined with stochastic shortest path models (MDPs), can be employed to refine the strategies of professional golfers and predict future performances. We present a comprehensive methodology for this objective, proving its computational feasibility. This sets the stage for more in-depth exploration into leveraging data available to professional and amateurs for strategic optimization and forecasting performance in golf. For the replicability of our results, and to adapt and extend the methodology and prototype solution, we provide access to all our codes and analyses (R and C++)

Wideband frequency domain detection using Teager-Kaiser energy operator

International audienceThis paper addresses wireless microphone sensing in the TV white space and efficient detection of narrowband FM modulation signals. To this end, a wideband frequency domain analysis is proposed. The required Fast Fourier Transform for this operation may be shared between sensing analysis and modulation functions. A particular decision metric is then studied for the analysis of wireless microphone signals based on the Teager-Kaiser energy operator. Simulation results show that 6 dB of detection gain could be achieved when using a frequency domain analysis compared to time domain methods. The Teager-Kaiser detection leads to further improvement of 1.5 dB. This performance could be reached at no extra cost in term of complexity

GRAPMAN: Gradual Power Manager for Consistent Throughput of Energy Harvesting Wireless Sensor Nodes

International audienceIn this work, Wireless Sensor Network (WSN) applications that require long-term sustainability are considered. Energy harvesting forms a promising technology to address this challenge, by allowing each node to be entirely powered by energy harvested from its environment. To be sustainable, each node must dynamically adapt its Quality of Service (QoS), regarding the harvested energy using a power management strategy. This strategy is implemented on each node by the Power Manager (PM). In this paper, GRAPMAN (GRAdual Power MANager) is proposed, a novel PM for Energy-Harvesting WSN (EH-WSN) powered by pseudo-periodic energy sources. Unlike most state of the art PMs, GRAPMAN aims to achieve high average throughput while maintaining consistent QoS, i.e. with low fluctuations with respect to time, by looking for the highest throughput that can be supplied by the node over a finite time horizon while remaining sustainable. We show through extensive trace-driven network simulations that GRAPMAN outperforms state of the art PMs in both average throughput and throughput consistency

Low complexity antenna diversity front-end: Use of code multiplexing

International audienceIn this paper, we address the architecture of an antenna diversity receiver and we aim to reduce the complexity of the analog front-end. To this end, an innovative architecture is introduced based on code multiplexing. This architecture uses the direct sequence spread spectrum technique in order to multiplex the different antennas contributions through a single demodulator. Simulation and measurement results show that, in a Gaussian case, the bit error rate does not increase so much with the multiplexing. The complexity evaluation shows that the proposed architecture significantly reduces the power consumption of the front-end

An FPGA Software Defined Radio Platform with a High-Level Synthesis Design Flow

International audienceSoftware defined radio (SDR) opens a new door to future Internet of Things with higher degree of designing flexibility in context of wireless system development. Prototyping a remote implementation of wireless protocols on a hardware over the web requires a highly versatile software radio platform along with laid-back designing tools. To this aim, an FPGA-based SDR scheme has been proposed combining Virtex-6 Perseus 6010 platform capabilities and a design flow based on High-Level Synthesis (HLS) tools. A full IEEE 802.15.4 (ZigBee) physical layer has been implemented on the proposed platform from a C-language dataflow specification. All the results have been analyzed to lead to a fair comparison between different design flows. Although the proposed SDR has some designing issues, it shows a noticeable designing potentiality to flexible prototyping of future wireless systems

Energy-Aware Computing via Adaptive Precision under Performance Constraints in OFDM Wireless Receivers

International audienceTo cope with rapid variations of channel parameters , wireless receivers are designed with a significant performance margin to reach a given Bit Error Rate (BER), even for the worst-case channel conditions. Indeed, one of the steps during the design phase is the choice of the architecture bit-width, and the smallest wordlength that ensures the correct behaviour of the receiver is usually chosen. In this paper, an adaptive precision OFDM receiver is proposed. Significant energy savings come from varying at run time processing bit-width, based on estimation of channel conditions, without compromising the BER constraints. To validate the energy savings, the energy consumption of basic operators has been obtained from real measurements for different bit-widths on a FPGA and a processor using soft SIMD. Results show that up to 63% of the dynamic energy consumption can be saved using this adaptive technique

Channel-Aware Energy Optimization of OFDM Receivers Using Dynamic Precision Scaling in FPGAs

International audienceTo reduce the energy consumption of Orthogonal Frequency-Division Multiplexing (OFDM) systems, a new variable word-length method is presented in this paper. A simulation based approach is used: the optimized fixed-point implementation of an OFDM receiver is found for different simulated channel conditions, depending on the Signal-to-Noise Ratio (SNR) and the channel type. During the execution, the receiver estimates the channel conditions and chooses the optimum word-length to decode the received information. A realistic energy consumption of the receiver is estimated with a library that contains the energy consumption of Field-Programmable Gate Array (FPGA) basic operators depending on the bit-width, obtained from experimental data. Up to 57% of the dynamic energy can be saved using this method

Nouvelles formes d'ondes par paquets d'ondelettes pour les modulations multiporteuses

La qualité d'une transmission multiporteuses dépend directement des formes d'onde modulantes utilisées. Dans cet article, la Wavelet Packet Modulation (WPM) est appliquée aux communications sans fil et une nouvelle modulation est proposée qui utilise les ondelettes complexes. Nous montrons que, pour une transmission à travers un canal multi-trajets, l'utilisation des ondelettes complexes permet d'améliorer l'utilisation des ondelettes réelles. Nous montrons également que l'utilisation des ondelettes permet de réduire considérablement les fluctuations d'enveloppe du signal transmis. Les performances de la WPM sont comparées à celle de la modulation OFDM

IQ imbalance reduction in a SMI multi-antenna receiver by using a code multiplexing front-end

International audienceIn this paper, we address the IQ imbalance sensibility of the code multiplexing front-end architecture. This innovative architecture has been recently proposed in order to reduce the analog complexity of an antenna diversity receiver front-end. An interesting characteristic of this structure is that the resulting IQ imbalance is equal for each received baseband signal. Associated with Single Matrix Inversion algorithm, this property ensures a high IQ imbalance robustness. A global antenna diversity system including analog front-end and digital processing has been implemented in order to perform simulation validation. Results show that the bit error rate does not increase significantly with the multiplexing and this increase is compensated for a high IQ imbalance