FUTURE TRENDS OF MOBILE AND PERSONAL COMMUNICATIONS (Invited Paper) Theodore S. Rappaport Mobile & Portable Radio Research Group Bradley Department of Electrical Engineering Virginia Tech Blacksburg, VA 24061-0350 email: [email protected] This tutorial paper provides an overview of the fundamental concepts used in cellular radio communications, and illustrates the likely evolution and growth of t...

Although most people think of Text Messaging as a recent phenomenon, they do not realize that amateur radio has had text messaging for over a century. This was recently well demonstrated on the Tonight Show with Jay Leno when two old hams using CW beat the socks off of two hip teenagers using text messaging on their cell phones. [0] Even though CW has yielded some turf to newer digital modes, a...

Radio communications via channels already occupied by traditional telecommunication systems can be achieved by using ultrawideband (UWB) radio where extremely wideband wavelets are used in order to reduce the power spectral density (psd) of transmitted signal. Since the recovery of these UWB carriers is not feasible, noncoherent demodulation techniques have to be used. The letter evaluates and ...

Spectrum sensing is an essential concept in cognitive radio. It exploits the inefficient utilization of radio frequency spectrum without causing destructive interference to the licensed users. In this paper we considered spectrum sensing of Digital Video Broadcast Terrestrial (DVB-T) signal in different scenario. We compared various spectrum sensing algorithms that make use of the second order ...

Theodore S. Rappaport Mobile and Portable Radio Research Group Bradley Department of Electrical Engineering Virginia Polytechnic Institute and State University Blacksburg, VA 24061-0111 The Mobile and Portable Radio Research Group (MPRG) is a relatively new research group at Virginia Tech. Founded in the Spring of 1990, it is conducting basic and applied research in the areas of radio propagati...

The proposed Low Frequency Array will be a powerful new radio telescope operating in the 15 to 240 MHz range. LOFAR will be a fully digital instrument with tens of thousands of antennas and receivers. In the currently proposed configuration LOFAR will also be capable of operating as a high performance passive radar system using FM radio stations as signals of opportunity. In this mode of operat...

Digital data collected from each element of a L-shaped wide-aperture HF radar aperture can be examined offline with various beamforming and direction finding algorithms to assess statistical characteristics of received signals. This paper examines data on radio sources propagating to the HF radar via refraction off the ionosphere. The variations of the spatial properties of radio sources are ex...

Abstract. We describe an hierarchical, frequency-domain beamforming architecture for synthesising a sky beam from the wideband antenna feeds of digital aperture arrays. The development of densely-packed, all-digital aperture arrays is an important area of research required for the Square Kilometre Array (SKA) radio telescope. The design of real-time signal processing systems for digital apertur...

Wireless technology is creating a revolution in communications. While systems such as broadcast radio and television have been around for many years, many new types of wireless communication systems are emerging such as digital cellular, personal communications services (PCS), and packet radio. Two powerful techniques are usually employed to make communication over wireless mobile fading channe...

Abstract This project deals with design of analog to digital converters for software radio applications. Among various ADC architectures, continuous time bandpass (CTBP) sigma-delta ADC was found to be the best architecture for software radio applications. A new CTBP sigma-delta architecture with NRZ DAC is proposed for improved jitter performance. A complete on-chip solution with integrated PL...