Interference Aspects of Adaptive Modems over Slow Rayleigh Fading Channels

Adaptive modulation can achieve channel capacity gains by adapting the number of bits per transmission symbol on a burst-by-burst basis, in harmony with channel quality fluctuations. This is demonstrated in the paper for target bit error rates of 1 and 0.01%, respectively, in comparison to conventional fixed modems. However, the achievable gains depend strongly on the prevalent interference levels and hence interference cancellation is invoked on the basis of adjusting the demodulation decision boundaries after estimating the interfering channel’s magnitude and phase. Using the modem-mode switching levels of Table X and with the aid of interference cancellation, target BERs of 1 and 0.01% can be maintained over slow-fading channels for a wide range of channel Signal-to-noise ratios (SNR) and Signal-to-interference ratios (SIR), as seen in Figs. 20 and 21, respectively. Index Terms—Burst-by-burst adaptive modulation (modems), cochannel interference, interference cancellation

Hard Scattering Based Luminosity Measurement at Hadron Colliders

A strategy to determine the luminosity at Hadron Colliders is discussed using the simultaneous W-boson and Z-boson event counts. The emphasis of the study will be on the uncertainty induced by the parton density functions. Understanding this source of uncertainties is crucial for a reliable luminosity determination using the W-boson and Z-boson events. As an example we will use the D0 run 1 results to extract the luminosity using the vector boson events and compare the result with the traditional method. Subsequently we will look at the implications for the top cross section uncertainties using the extracted luminosity.Comment: 15 pages, 2 (colored) figure

W Plus Heavy Quark Production at the Tevatron

We summarize the motivations for and the status of the calculation of the $W +$ heavy quark production process in $p \bar p$ colliders to Next-to-Leading Order in QCD. This process can be used to constrain the strange quark distribution function at high $Q^2$ at the Tevatron, and also to study the bottom content of $W+1$~jet events. In addition, when crossed, the calculation essentially describes the single top quark production process to Next-to-Leading Order in QCD.Comment: Presented by S. Keller at DPF94 Meeting, Albuquerque, New Mexico, August 1-6,1994. 4 pages, no macros, no figures. Fermilab-Conf-94/260-T, FSU--HEP--940817. A postscript file is available via anonymous ftp at hepsg1.physics.fsu.edu, file is /pub/keller/fsu-hep-940817.p