Learn More
This article describes the modeling of ultra-wideband wireless propagation channels, especailly for the simulation of personal area networks. The IEEE 802.15.3a standards task group has established a standard channel model to be used for the evaluation of PAN physical layer proposals. We discuss the standard model, the measurements that form its basis, and(More)
—We suggest a novel approach to handle the ongoing explosive increase in the demand for video content in wireless/mobile devices. We envision femtocell-like base stations, which we call helpers, with weak backhaul links but large storage capacity. These helpers form a wireless distributed caching network that assists the macro base station by handling(More)
—We establish a statistical model for the ultra-wide bandwidth (UWB) indoor channel based on an extensive measurement campaign in a typical modern office building with 2-ns delay resolution. The approach is based on the investigation of the statistical properties of the multipath profiles measured in different rooms over a finely spaced measurement grid.(More)
A look at positioning aspects of future sensor networks. This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such(More)
This paper presents an overview of UWB propagation channels. It first demonstrates how the frequency selec-tivity of propagation processes causes fundamental differences between UWB channels and "conventional" (narrow-band) channels. The concept of pathloss has to be modified, and the well-known WSSUS model is not applicable anymore. Next, describe(More)
—We present a new architecture to handle the ongoing explosive increase in the demand for video content in wireless networks. It is based on distributed caching of the content in femto-basestations with small or non-existing backhaul capacity but with considerable storage space, called helper nodes. We also consider using the mobile terminals themselves as(More)
U ltra-wideband (UWB) radios have relative bandwidths larger than 20% or absolute bandwidths of more than 500 MHz. Such wide bandwidths offer a wealth of advantages for both communications and radar applications. In both cases, a large band-width improves reliability, as the signal contains different frequency components, which increases the probability(More)
—Video on-demand streaming from Internet-based servers is becoming one of the most important services offered by wireless networks today. In order to improve the area spectral efficiency of video transmission in cellular systems, small cells heterogeneous architectures (e.g., femtocells, WiFi off-loading) are being proposed, such that video traffic to(More)
| To make transportation safer, more efficient, and less harmful to the environment, traffic telematics services are currently being intensely investigated and developed. Such services require dependable wireless vehicle-to-infrastructure and vehicle-to-vehicle communications providing robust con-nectivity at moderate data rates. The development of such(More)