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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 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)
—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)
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)
—Vehicle-to-vehicle (VTV) wireless communications have many envisioned applications in traffic safety and congestion avoidance, but the development of suitable communications systems and standards requires accurate models for the VTV propagation channel. In this paper, we present a new wideband multiple-input-multiple-output (MIMO) model for VTV channels(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)
We propose a new scheme for increasing the throughput of video files in cellular communications systems. This scheme exploits (i) the redundancy of user requests as well as (ii) the considerable storage capacity of smartphones and tablets. Users cache popular video files and-after receiving requests from other users-serve these requests via device-to-device(More)
— A wideband space-time channel model is defined, which captures the multiple dependencies and variability in multi-cell, system-wide operating environments. The model provides a unified treatment of spatial and temporal parameters, giving their statistical description and dependencies across a large geographical area for three outdoor environments(More)