223 research outputs found
Visualisation Tool for Ad Hoc Networks - ViTAN v1.0
No full textthis document. We hope that others find ViTAN helpful and welcome your feedback. Also, we welcome additions and refinements to the tool. 2 Installation After having downloaded the ViTAN tool (see Section A for details), the file has to be untared and unzipped: tar zxvf ViTANv10.tar.gz This process generated a subdirectory called ViTAN. Be sure that you have the following files in the subdirectory (dates and user names are di#erent, file names are the same): 1 fitzek users 429 Nov 26 13:32 ViTAN.bib 1 fitzek users 13838 Nov 26 13:34 bridge.fig 1 fitzek users 422 Nov 13 17:40 bridge.input 1 fitzek users 46133 Nov 26 13:34 bridge.jpg 1 fitzek users 6554 Nov 26 13:34 bridge.pdf 1 fitzek users 15138 Nov 26 13:34 bridge.png 1 fitzek users 10135 Nov 26 13:34 chain.fig 1 fitzek users 206 Nov 13 17:03 chain.input 1 fitzek users 43910 Nov 26 13:34 chain.jpg 1 fitzek users 1371 Nov 26 13:34 chain.output 1 fitzek users 4517 Nov 26 13:33 chain.pdf 1 fitzek users 13999 Nov 26 13:33 chain.png 1 fitzek users 11144 Nov 26 13:34 chain2.fig 1 fitzek users 216 Nov 26 13:28 chain2.input 1 fitzek users 44096 Nov 26 13:34 chain2.jpg 1 fitzek users 4528 Nov 26 13:34 chain2.pdf 1 fitzek users 14170 Nov 26 13:34 chain2.png 1 fitzek users 13852 Nov 26 13:34 circle . fig 1 fitzek users 361 Nov 18 10:52 circle . input 1 fitzek users 49817 Nov 26 13:34 circle . jpg Copyright at acticom. All Rights reserved. 1 fitzek users 6539 Nov 26 13:34 circle . pdf 1 fitzek users 16326 Nov 26 13:34 circle . png 1 fitzek users 0 Nov 26 13:34 directory 1 fitzek users 1173 Nov 26 13:33 export 1 fitzek users 36897 Nov 26 13:34 manhattan.fig 1 fitzek users 1692 Nov 13 17:41 manhattan.input 1 fitzek users 93420 Nov 26 13:34 manhattan.jpg 1 fitzek users 17199 Nov 2..
Stretchable and Skin-Conformable Conductors Based on Polyurethane/Laser-Induced Graphene
No full textThe 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
Error Control Techniques for Efficient Multicast Streaming in UMTS Networks
No full textIn this paper we introduce techniques for efficient multicast video streaming in UMTS networks. Multicast streaming is based on the fact that the same video content is conveyed to multiple users in the same cell. Efficient multicast data delivery in UMTS is still an open issue. In particular, suitable solutions have to be found to cope with wireless channel errors, while maintaining both an acceptable channel utilization and a controlled delivery delay over the wireless link between the serving base station and the mobile terminals. We first highlight that standard solutions such as unequal error protection of the video flow are ineffective in the UMTS systems due to the large feedback delay. Then, we propose a local approach to solve errors directly at the UMTS link layer while keeping a reasonably high channel efficiency and saving, as much as possible system resources. The solution we propose in this paper is based on the usage of the common channel to serve all the interested users in a cell. In this way, we can save resources with respect to the case where multiple dedicated channels are allocated. Moreover, we present a hybrid ARQ proactive protocol that, at the cost of some redundancy (added on the link layer flow), is able to greatly improve channel efficiency with respect to the simple ARQ case by making the use of a single common channel for multicast data delivery feasible. Furthermore, we envision the usage of suitably encoded video streams
Visualization Tool for Ad Hoc Networks - ViTAN v1.1
No full textthis document. We hope that others find ViTAN helpful and welcome your feedback. Also, we welcome additions and refinements to the tool. 2. Installation After having downloaded the ViTAN tool (see Section A for details), the file has to be untared and unzipped: tar zxvf ViTANv11.tar.gz This process generated a subdirectory called ViTAN. Be sure that you have the following files in the subdirectory (dates and user names are di#erent, file names are the same): 1 p s e e l i ng p s e e l i ng 178653 Feb 19 18 : 14 100- . f i g 1 p s e e l i ng p s e e l i ng 177427 Feb 1 9 1 8 : 1 4 1 0 0 . f i g 1 p s e e l i ng p s e e l i ng 22142 Feb 17 08 : 57 100- . i nput 1 p s e e l i ng p s e e l i ng 22542 Feb 1 7 0 8 : 5 7 1 0 0 . i nput 1 p s e e l i ng p s e e l i ng 22948 Feb 17 08 : 57 100+ . i nput 1 p s e e l i ng p s e e l i ng 188527 Feb 19 18 : 14 100- . j pg 1 p s e e l i ng p s e e l i n g 149096 Feb 1 9 1 8 : 1 4 1 0 0 . j pg 1 p s e e l i ng p s e e l i n g 144617 Feb 19 18 : 14 100- . pd f 1 p s e e l i ng p s e e l i n g 144113 Feb 1 9 1 8 : 1 4 1 0 0 . pd f 1 p s e e l i ng p s e e l i n g 102705 Feb 19 18 : 14 100- . png 1 p s e e l i n g p s e e l i n g 79881 Feb 1 9 1 8 : 1 4 1 0 0 . png 1 p s e e l i n g p s e e l i n g 39428 Feb 1 7 1 8 : 0 2 1 . f i g 1 p s e e l i n g p s e e l i n g 187242 Feb 1 7 0 8 : 5 7 3 0 0 . i nput 1 p s e e l i n g p s e e l i n g 114376 Feb 1 9 1 8 : 1 4 3 0 . f i g 1 p s e e l i n g p s e e l i n g 35007 Feb 19 18 : 14 30+ . f i g 1 p s e e l i n g p s e e l i n g 2675 Feb 1 7 0 8 : 5 9 3 0 . i nput 1 p s e e l i n g p s e e l i n g 2498 Feb 17 08 : 59 30+ . i nput 1 p s e e l i n g p s e e l i n g 172180 Feb 1 9 1 8 : 1 4 3 0 . j pg 1 p s e e l i n g p s e e l i n g 100066 Feb 19 18 : 14 ..
A symbiotic perspective on low-cost cellular and multihop WLAN interworking solutions
No full textInterworking between wireless local area networks (WLANs) and cellular networks (such as 2G and 3G) is expected to break new ground for sophisticated business models. Omnipresent cellular networks have a well-defined infrastructure, but lack capability to provide broadband and/or real-time services (e.g., streaming video and gaming). Conversely, WLANs supports high data rates, while the infrastructure for service provision is vague. Therefore, the combination of the cellular core network infrastructure with its service centers and accounting capabilities with the achievable data rate of WLANs can provide the possibility of offering new services to the customer. This interworking is being considered in different standardization and operational activities. WLAN hotspots are already on the way, but the high installation costs of WLANs, especially for larger hotspots, are repressing a faster evolution. The installation costs are mainly driven by the cabling infrastructure. To reduce these costs and to gain flexibility, we advocate exploiting multihop capability for WLAN coverage extension by introducing the concept of virtual access points. However, the high data rates of WLAN solutions are hindered by the standard IEEE 802.11 MAC protocol, which has been shown to be inappropriate for multihop operation. In this article we consider an improved version of the IEEE 802.11 MAC that involves only minor changes to the existing standard, which allows for a faster deployment and the usability of the approach in existing interworking scenarios. The specific contribution of this article is a thorough exploration, by means of simulation, of the performance of such an approach. In particular, we demonstrate that the enhanced MAC is capable of offering high data rates in multihop WLAN extensions to the cellular network. Besides the networking structure, a pertinent issue in the WLAN cellular symbiosis is security. In this respect we discuss multihop operation in light of current interworking (security) activities
Link layer algorithms for efficient multicast services in 3G multicellular systems
No full textWe introduce error control algorithms for multicast delivery in 3G cellular networks. For efficiency reasons, the delivery of multicast flows is usually achieved by allocating a common channel in the forward direction. This enables multiple users to be served by a single physical resource. However, different users are affected by independent channel error processes and new techniques, different from plain ARQ, have to be found to perform error recovery. These new algorithms are needed to deliver the multicast flow in an efficient manner and to enable a reliable, performant and network operator inexpensive, multicast service. Different hybrid ARQ algorithms for the error recovery of multicast flows over common channels are proposed and their performance is evaluated both analytically and by simulation. The proposed solutions have been found to be effective and advantageous over plain ARQ techniques. Results on the achievable video quality are reported for the multicast video streaming case by considering the H.263 video coding format
Complementing 3G Cellular Networks by Multi Hop Capabilities of an Enhanced MAC Protocol for Wireless LAN
No full textInterworking between wireless LANs and 3G networks is expected to break new ground for sophisticated business models. The combination of the 3G core network infrastructure (with service centers and accounting capabilities) and the achievable data rate of WLANs give the possibility to offer new services. WLAN hotspots are on the way, but the high installation costs of WLAN, especially for larger hotspots, repress a faster evolution. The installation costs are mainly driven by the cabling infrastructure. In the past we have already introduced an enhanced MAC protocol for multi hop networks without any infrastructure. In this paper we investigate the MAC performance for a multi hop scenario, enabling low costs WLAN networks with infrastructure that are coupled with 3G networks. This approach should allow network providers to have a fast return on their investments. As video services are expected to be one of the future key--services, we present a detailed performance evaluation of different network topologies transmitting high quality video traffic
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