A comparison of DFT and SVD based channel estimation in MIMO OFDM systems

In this paper two simplified transform based estimators for MIMO OFDM systems using the DFT and an SVD based transform are compared over a tapped delay line channel model. In the resulting symbol error rate plots, it is seen that the DFT based estimator experiences an error floor caused by the mismatch between the discrete time model and a continuous time reality. This error floor becomes a problem at high SNR levels where high data-rate systems can be expected to operate. When using an SVD based estimator it is seen that this error floor is reduced at the cost of a somewhat increased estimator complexit

Strong, Bold, and Kind: Self-Control and Cooperation in Social Dilemmas

We develop a model relating self-control, risk preferences and conflict identification to cooperation patterns in social dilemmas. We subject our model to data from an experimental public goods game and a risk experiment, and we measure conflict identification and self-control. As predicted, we find a robust association between self-control and higher levels of cooperation, and the association is weaker for more risk-averse individuals. Free riders differ from other contributor types only in their tendency not to have identified a self-control conflict in the first place. Our model accounts for the data at least as well as do other models

Optimum data rate in cellular systems

The spectrum efficiency in a cellular radio system is affected by the data rates used in the system. High data rates may result in low spectrum efficiency if the frequency reuse is low. The spectrum efficiency may be enhanced by using adaptive modulation with carefully chosen data rates. We present an analytical method, based on a lower bound on the BER, for finding the best data rates. The method results in the best code rates to be used with QPSK, 8-PSK, and 16-QAM in an adaptive fashion. The general conclusion is that a large number of carefully chosen data rates enhances the spectrum efficienc