Variable pulse position modulation (VPPM) is a new modulation scheme that supports simultaneously illumination with dimming control and communication. In this paper, the transmitter, optical wireless channel, and receiver structure of VPPM were modeled mathematically, and their error performance for examining the communication performance according to dimming level and data rate was analyzed. T...

Ultra-wideband radio (UWB) is a rapidly developing wireless technology that promises unprecedented data rates for short-range commercial radios, combined with precise locationing and high energy efficiency. These benefits stem from the use of wide bandwidths and impulse signaling, implying high channel capacity and precise time resolution. UWB has been used for military radar and imaging since ...

Besides advanced telecommunications techniques, the most prominent evolution of wireless networks is the densification of network deployment. In particular, the increasing access points/users density and reduced cell size significantly enhance spatial reuse, thereby improving network capacity. Nevertheless, does network ultra-densification and over-deployment always boost the performance of wir...

A simple technique to estimate the position of a given mobile source inside a building is based on the received signal strength. For this methodology to have a reasonable accuracy, radio visibility of the mobile by at least three access points is required. To reduce the number of the required access points and therefore simplify the underlying coverage design problem, we propose a novel scheme ...

This article presents a closed-loop transmitter for wireless power transfer with automatic resonance frequency tracking to maintain high efficiency in the over-coupled region. The consists of source oscillator, amplifier (PA), PA driver, matching network, and feedback circuitry. By injecting resonant output coupled antenna coils into oscillator form positive loop, is injection-locked functions ...

Many rate adaptation algorithms have been proposed for IEEE 802.11 Wireless LAN devices and most of them operate in an open-loop manner, i.e., the transmitter adapts its transmission rate without using the feedback from the receiver. A key problem with such transmitter-based rate adaptation schemes is that they do not consider the collision effect. Accordingly, they often result in severe throu...

Using antenna arrays at both sides of the wireless communication link (MIMO systems) can result in high channel capacity provided that the channel is ideal, i.e., propagation medium is rich scattering or Rayleigh fading, the antenna arrays at both sides are uncorrelated. Also, the availability of channel side information (CSI) at the transmitter further enhances the capacity of ideal channels. ...