Optimum designs of high mobility wireless systems with channel estimation errors

This research studies the optimum system designs of high mobility wireless communication systems with imperfect channel state information. In high mobility systems, the channel estimation error is usually inevitable and might have significant impacts on system performance. The impacts of channel estimation errors on system performance are quantified through the development of a spectral efficiency lower bound. With the help of the asymptotic analysis of the channel estimation mean squared error, the spectral efficiency lower bound is expressed as explicit functions of a number of system parameters, such as the maximum Doppler frequency, the percentage of pilots in the transmitted symbols, and the ratio of energy allocated between data symbols and pilot symbols. The optimum pilot percentage and energy allocation factor that jointly maximise the spectral efficiency lower bound are identified through analytical studies. It is discovered that, in term of maximising spectral efficiency, the optimum performance can be achieved by optimising the energy allocation factor when the pilots sample the fast time-varying fading at its Nyquist rate.