Model-based pilot and data power adaptation in psam with periodic delayed feedback

We consider the optimum design of pilot-symbol-assisted modulation (PSAM) schemes with feedback. The received signal is periodically fed back to the transmitter through a noiseless delayed link and the time-varying channel is modeled as a Gauss-Markov process. We optimize a lower bound on the channel capacity which incorporates the PSAM parameters and Kalman-based channel estimation and prediction. The parameters available for the capacity optimization are the data power adaptation strategy, pilot spacing and pilot power ratio, subject to an average power constraint. Compared to the optimized open-loop PSAM (i.e., the case where no feedback is provided from the receiver), our results show that even in the presence of feedback delay, the optimized power adaptation provides higher information rates at low signal-to-noise ratios (SNR) in medium-rate fading channels. However, in fast fading channels, even the presence of modest feedback delay dissipates the advantages of power adaptation.

The financial crisis and nuclear power

An assessment of the impact of the financial crisis on the prospects for new nuclear power plant orders worldwide.

The future of energy: are competitive markets and nuclear power the answer?

The inaugural lecture of Professor Stephen Thomas at the University of Greenwich, 4th February 2010. It examines whether further pursuit of competition in energy markets and expansion in the role of nuclear power can be the main elements in a policy to meet goals of security, sustainability and affordability.