In this paper a reconfigurable ultra-wideband (UWB) impulse radio (IR) transmitter is presented. The IR signal is synthesized at an intermediate frequency (IF) by employing a multi-Nyquist digital-to-analog converter (DAC) with 12 bit resolution and an update rate of 2.3 GHz. Digital generation of signals in a field programmable gate array (FPGA) guarantees very high flexibility of the reconfig...

Recent research shows that more than 70% of the available spectrum is not utilized efficiently. The bandwidth becomes expensive due to a shortage of frequencies. Therefore for efficient utilization of spectrum, we need to sniff the spectrum to determine whether it is being used by primary user or not. The term cognitive radio refers to the adoption of radio parameters using the sensed informati...

We propose a method to track a periodic RF transmitter using a mobile receiver. By estimating the difference in time-of-arrival (TOA) of the periodic messages at different locations along its trajectory, the receiver is able to estimate the transmitter location. A major challenge lies in separating the time offset due to receiver movement from the time offset due to local oscillator (LO) drift....

Cable service providers are upgrading their distribution systems to stay ahead of the increased consumer demand for data. The nature of the transmission systems is evolving from a multi-cast system, where all subscribers are sent the same signal, to a combined multi-cast and narrowcast system, where some content is shared by all subscribers, and some content is directed to a particular subscrib...

This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals...

The OFDM based terrestrial digital video broadcasting system (DVB-T) can be utilized for asymmetric Internet access with a downlink peak bit rate of 10-20Mbps. A narrow-band cellular communications system can be used as uplink. This paper is a comparison of centralized dynamic radio resource management schemes for this downlink packet radio system. Spectrum efficiency in bit/s/Hz/transmitter, a...

Large-scale radio systems for multiple users, such as those used in mobile phone networks, are often based on a cellular structure (Hale 1980; Macario 1997; MacDonald 1979). The service area is divided into cells and each cell is serviced by one transmitter, which communicates with users within the cell using a particular radio channel or set of channels. In any particular application the avail...

Radio telemetry has been widely used to study the space use and movement behaviour of vertebrates, but transmitter sizes have only recently become small enough to allow tracking of insects under natural field conditions. Here, we review the available literature on insect telemetry using active (battery-powered) radio transmitters and compare this technology to harmonic radar and radio frequency...

This chapter presents a study on the interference caused by Secondary Users (SUs) due to miss-detection errors and its effects on the capacity-outage performance of the Primary User (PU) in a cognitive radio network assuming Rayleigh and Nakagami fading channels. The effect of beacon transmitter placement on aggregate interference distribution and capacity-outage performance is studied consider...

This paper presents an ultra-low-standby-power radio transmitter that was designed for applications with extreme energy storage and/or energy harvesting constraints. By utilizing aggressive power gating techniques within a low-complexity architecture featuring only a single RF stage, the transmitter achieved a standby power consumption of 39.7 pW. The architecture employed a direct-RF power osc...