Real-Time Object Detection with Automatic Switching between Single-Board Computers and the Cloud

We present a wireless real-time object detection system utilizing single-board devices, cloud computing platforms and web-streaming. Currently, most inference applications stat- ically perform tasks either on local machines or remote cloud servers. However, devices connected through cellular technolo- gies face volatile network conditions, compromising detection performance. Furthermore, while the limited computing power of single-board computers degrade detection correctness, exces- sive power consumption of machine learning models used for inference reduces operation time. In this paper, we propose a dynamic system that monitors embedded device’s wireless link quality and battery level to decide on detecting objects locally or remotely. The experimental results show that our dynamic offloading approach could reduce devices’ energy usage while achieving high accuracy, real-time object detection. Index Terms—Machine learning, WebRTC, object detection

Code correcteurs d'effacements et accès opportuniste au spectre (OSA)

The emergence of new devices especially the smartphones and tablets having a lot of new applications have rocketed the wireless traffic in recent years and this is the cause of main surge in the demand of radio spectrum. There is a need of either more spectrum or to use existing spectrum more efficiently due to dramatic increase in the demand of limited spectrum. Among the new dynamic access schemes designed to use the spectrum more efficiently opportunistic spectrum access (OSA) is currently addressed when one or more secondary users (SU) are allowed to access the channel when the PU is not transmitting. The erasure correcting codes are therefore envisioned to recover the lost data due to sensing impairments. We define the parameter efficiency of SU and optimize it in-terms of spectrum utilization keeping into account sensing impairments, code parameters and the activity of PU. Finally, the spectrum access for multiple secondary users is addressed when there is no primary and each user has equal right to access the channel. The interesting scenarios are Cognitive radio networks and WiFi where 802.11 protocol gives the specification for MAC layer. The throughput curvesachieved by retransmission and using various erasure correcting codes are compared. This modification in MAC layer will reduce the long waiting time to access the channel, as the number of users are increased.Les années récentes ont vu l’explosion du trafic sur les réseaux mobiles depuis l’apparition de nouveaux terminaux (smartphones, tablettes) et des usages qu’ils permettent, en particulier les données multimédia, le trafic voix restant sensiblement constant. Une conséquence est le besoin de plus de spectre, ou la nécessité de mieux utiliser le spectre déjà alloué. Comme il n’y a pas de coordination entre les utilisateurs secondaire(s) et primaire, avant toute transmission les premiers doivent mettre en œuvre des traitements pour détecter les périodes dans lesquelles l’utilisateur primaire transmet, ce qui est le scénario considéré dans cette thèse. Nous considérons donc une autre approche, reposant sur l’utilisation de codes correcteurs d’effacements en mode paquet. La dernière partie de la thèse aborde un scénario dans lequel il n’y a plus d’utilisateur primaire, tous les utilisateurs ayant le même droit à transmettre dans le canal. Nous décrivons une modification de la couche MAC du 802.11 consistant à réduire les différents temps consacrés à attendre (SIFS, DIFS, backoff, . . .) afin d’accéder plus souvent au canal, au prix de quelques collisions supplémentaires qu’il est possible de récupérer en mettant en œuvre des codes correcteurs d’effacements

Improving the erasure recovery performance of short codes for opportunistic spectrum access

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Exploiting Short Block and Concatenated Codes for Reliable Communications within the Coexistence of 5G-NR-U and WiFi

Unlicensed spectrum offers opportunities for cellular mobile network operators, where traffic can be offloaded from licensed to unlicensed bands. Modern heterogeneous technologies such as 5G New Radio (NR) and WiFi can simultaneously operate on ISM and UNII bands under strict coexistence rules. While satisfying harmonious coexistence has largely been studied in LTE/4G, an emerging issue for future deployment is to reduce latency and to guarantee reliable communications, in the direction of achieving URLLC. This work mainly focuses on the critical issues arising in the coexistence of Listen Before Talk (LBT) systems, sharing common infrastructure of 5G NRU and WiFi when operating under imperfect energy detection sensing. We consider the application of short, concatenated and product erasure correcting codes to recover missing data in LBT-based systems due to collisions. The goal is to enhance spectrum utilization with reduced delay and to achieve reliable communications under LBT and various sensing impairments, with code parameters such as block length, rate and minimum distance. By means of concatenation, we construct a series of sophisticated erasure block codes with less decoding complexity using Tanner Graph based decoding. Furthermore, we develop an analytical model to derive a closed-form expression using Gaussian approximation of spectrum utilization efficiency. The efficiency achieved using short, concatenated and product block codes is compared with the various low-density parity-check (LDPC) correcting ensembles under various levels of user activities, built by two state Gilbert-Elliott model. We provide detailed comparisons in respect of global throughput and failure probability of codes under varied number of coexisting users. Our results show that the proposed codes can achieve at least 20% higher efficiency at 0.1 false alarm probability and 30% less failure probability under high contention scenarios

On the Interplay of Sensing and Erasure Correction in Opportunistic Spectrum Access

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Single parity check product codes for erasure recovery in opportunistic spectrum access

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Error recovery technique for coarse-grained reconfigurable architectures

International audienceThis paper presents the implementation of the error recovery scheme from temporary faults, applicable for datapaths of coarse-grained reconfigurable architectures. We have chosen the DART architecture as a vehicle to study various aspects related to implementation of the instruction retry in a complex highly parallel reconfigurable system. Synthesis results have confirmed the time, hardware, and power consumption efficiency of the proposed approach, which can be applied independently on the concurrent error detection scheme actually used

Novel architectural space exploration environment for multi-FPGA based prototyping systems

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