222 research outputs found
S-PRAC: Fast Partial Packet Recovery with Network Coding in Very Noisy Wireless Channels
Well-known error detection and correction solutions in wireless
communications are slow or incur high transmission overhead. Recently, notable
solutions like PRAC and DAPRAC, implementing partial packet recovery with
network coding, could address these problems. However, they perform slowly when
there are many errors. We propose S-PRAC, a fast scheme for partial packet
recovery, particularly designed for very noisy wireless channels. S-PRAC
improves on DAPRAC. It divides each packet into segments consisting of a fixed
number of small RLNC encoded symbols and then attaches a CRC code to each
segment and one to each coded packet. Extensive simulations show that S-PRAC
can detect and correct errors quickly. It also outperforms DAPRAC significantly
when the number of errors is high
Stretchable and Skin-Conformable Conductors Based on Polyurethane/Laser-Induced Graphene
The conversion of various polymer substrates into laser-induced graphene (LIG) with a CO2 laser in ambient condition is recently emerging as a simple method for obtaining patterned porous graphene conductors, with a myriad of applications in sensing, actuation, and energy. In this paper, a method is presented for embedding porous LIG (LIG-P) or LIG fibers (LIG-F) into a thin (about 50 μm) and soft medical grade polyurethane (MPU) providing excellent conformal adhesion on skin, stretchability, and maximum breathability to boost the development of various unperceivable monitoring systems on skin. The effect of varying laser fluence and geometry of the laser scribing on the LIG micro-nanostructure morphology and on the electrical and electromechanical properties of LIG/MPU composites is investigated. A peculiar and distinct behavior is observed for either LIG-P or LIG-F. Excellent stretchability without permanent impairment of conductive properties is revealed up to 100% strain and retained after hundreds of cycles of stretching tests. A distinct piezoresistive behavior, with an average gauge factor of 40, opens the way to various potential strain/pressure sensing applications. A novel method based on laser scribing is then introduced for providing vertical interconnect access (VIA) into LIG/MPU conformable epidermal sensors. Such VIA enables stable connections to an external measurement device, as this represents a typical weakness of many epidermal devices so far. Three examples of minimally invasive LIG/MPU epidermal sensing proof of concepts are presented: as electrodes for electromyographic recording on limb and as piezoresistive sensors for touch and respiration detection on skin. Long-term wearability and functioning up to several days and under repeated stretching tests is demonstrated
Pedestrian recognition using automotive radar sensors
The application of modern series production automotive radar sensors to
pedestrian recognition is an important topic in research on future driver
assistance systems. The aim of this paper is to understand the potential and
limits of such sensors in pedestrian recognition. This knowledge could be
used to develop next generation radar sensors with improved pedestrian
recognition capabilities. A new raw radar data signal processing algorithm is
proposed that allows deep insights into the object classification process.
The impact of raw radar data properties can be directly observed in every
layer of the classification system by avoiding machine learning and tracking.
This gives information on the limiting factors of raw radar data in terms of
classification decision making. To accomplish the very challenging
distinction between pedestrians and static objects, five significant and
stable object features from the spatial distribution and Doppler information
are found. Experimental results with data from a 77 GHz automotive radar
sensor show that over 95% of pedestrians can be classified correctly under
optimal conditions, which is compareable to modern machine learning systems.
The impact of the pedestrian's direction of movement, occlusion, antenna beam
elevation angle, linear vehicle movement, and other factors are investigated
and discussed. The results show that under real life conditions, radar only
based pedestrian recognition is limited due to insufficient Doppler frequency
and spatial resolution as well as antenna side lobe effects
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Author Correction: Persistent and reversible solid iodine electrodeposition in nanoporous carbons
Correction to: Nature Communications https://doi.org/10.1038/s41467-020-18610-6, published online 24 September 2020
Theory that Matters! Problem-based learning towards 5G Communication System and Standards
Theory that Matters! Problem-based learning towards 5G Communication System and Standard
Easy as Pi:A Network Coding Raspberry Pi Testbed
In the near future, upcoming communications and storage networks are expected to tolerate major difficulties produced by huge amounts of data being generated from the Internet of Things (IoT). For these types of networks, strategies and mechanisms based on network coding have appeared as an alternative to overcome these difficulties in a holistic manner, e.g., without sacrificing the benefit of a given network metric when improving another. There has been recurrent issues on: (i) making large-scale deployments akin to the Internet of Things; (ii) assessing and (iii) replicating the obtained results in preliminary studies. Therefore, finding testbeds that can deal with large-scale deployments and not lose historic data in order to evaluate these mechanisms are greatly needed and desirable from a research perspective. However, this can be hard to manage, not only due to the inherent costs of the hardware, but also due to maintenance challenges. In this paper, we present the required key steps to design, setup and maintain an inexpensive testbed using Raspberry Pi devices for communications and storage networks with network coding capabilities. This testbed can be utilized for any applications requiring results replicability
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