Transmit power control is a central technique for resource allocation and interference management in spread-spectrum wireless networks. With increasing popularity of spread-spectrum as a multiple access technique, there has been signiicant research in the area in recent years. While power control has been considered traditionally as a means to counteract the harmful eeect of channel fading, the...

Markets for spectrum were first proposed by Ronald Coase [1] as a way to efficiently allocate this resource. It took another forty years for primary markets to be developed (in the form of spectrum auctions) as the mechanism for assigning spectrum licenses to users. It is not a secret that secondary markets would be necessary to fully realize the benefits of economic allocation of spectrum. But...

This paper investigates the capacity of multiple relay channels in different fading and shadowing environments under spectrum-sharing constraints. We consider that a secondary user (SU) is allowed to share the spectrum band with a primary user (PU) provided that the SU’s transmit power remains below an interference power threshold set by the PU. Considering a scenario where the SU’s transmitter...

We implement an interferometric method to measure the orbital angular momentum (OAM) spectrum of photon pairs generated by spontaneous parametric down-conversion. In contrast to previous experiments, which were all limited by the modal capacity of the detection system, our method operates on the entire down-conversion cone and reveals the complete distribution of the generated OAM. In this geom...