Amdocs (Israel)

Solid-state NMR have been long used to probe atomic distances between nearby nuclear spins by virtue of the dipolar interaction. New technological advances have enabled simultaneous tuning of the radio-frequency resonance circuits to nuclei with close Larmor frequencies, bringing a great promise also to distance measurements between such nuclei, in particular for nuclei with a spin larger than one-half. However, this new possibility has also required modifications of those experiments since the two nuclei cannot be irradiated simultaneously. When measuring distances between a spin S=1/2 and a quadrupolar spin (S > 1/2), this drawback can be overcome by splitting the continuous-wave recoupling pulse applied to the quadrupolar nucleus. We show here that a similar adjustment to a highly-efficient phase-modulated (PM) recoupling pulse enables distance measurements between nuclei with close Larmor frequencies, where the coupled spin experiences a very large coupling. Such an experiment, split phase-modulated RESPDOR, is demonstrated on a 13C-81Br system, where the difference in Larmor frequencies is only 7%, or 11.2 MHz on a 14.1T magnet. The inter-nuclear distances are extracted using an unscaled analytical formula. Since bromine usually experiences particularly high quadrupolar couplings, as in the current case, we suggest that the split-PM-RESPDOR experiment can be highly beneficial for the research of bromo-compounds, including many pharmaceuticals, where carbon-bromine bonds are prevalent, and organo-catalysts utilizing the high reactivity of bromides. We show that for butyl triphenylphosphonium bromide, distances are in agreement with a low-hydration compound rather than a semi-clathrate form. The split-PM-RESPDOR experiment is suitable for distance measurement between any quadrupolar/spin-1/2 pairs, in particular when the quadrupolar spin experiences a significantly large coupling.

Cell selection is the process of determining the cell(s) that provide service to each mobile station. Optimizing these processes is an important step toward maximizing the utilization of current and future cellular networks. We study the potential benefit of global cell selection versus the current local mobile SNR-based decision protocol. In particular, we study the new possibility available in OFDMA-based systems, such as IEEE 802.16m and LTE-Advanced, of satisfying the minimal demand of a mobile station simultaneously by more than one base station. We formalize the problem as an optimization problem, and show that in the general case this problem is not only NP-hard but also cannot be approximated within any reasonable factor. In contrast, under the very practical assumption that the maximum required bandwidth of a single mobile station is at most an r-fraction of the capacity of a base station, we present two different algorithms for cell selection. The first algorithm produces a (1-r)-approximate solution, where a mobile station can be covered simultaneously by more than one base station. The second algorithm produces a 1-r/2-r-approximate solution, while every mobile station is covered by at most one base station. We complete our study by an extensive simulation study demonstrating the benefits of using our algorithms in high-loaded capacity-constrained future 4G networks, compared to currently used methods. Specifically, our algorithms obtain up to 20 percent better usage of the network's capacity, in comparison with the current cell selection algorithms.

We present and discuss the important business problem of estimating the effect of marketing activities on the Lifetime Value of a customer in the Telecommunications industry. We discuss the compone...