Efficient Rate-Power Allocation for OFDM in a Realistic Fading Environment

The implementation of practical adaptive resource allocation scheme remains a key criterion to be satisfied for realising spectrally efficient multitone wireless communications. The ever-increasing demand for spectrally efficient broadband wireless transmission technologies has spurred intensive research leading towards the implementation of adaptive OFDM and adaptive MIMO systems. Efforts in this direction have been frustrated however by the lack of a clear and accurate description of the fading behaviour typically encountered in the broadband wireless transmission environment. This has been partially been overcome by the use of mathematical modelling which captures certain large-scale characteristics of the channel and facilitates theoretical research. The "average" channel parameters gleaned from these processes is typically then used to inform the design and configuration of wireless networking equipment after the broad application of generous safety margins. The resulting solution is therefore quite robust to certain transient channel quality degradation yet the generous safety tolerances render it unable to exploit other transient transmission quality improvements We seek to overcome the problems associated with this approach by applying a theoretically sound novel adaptive resource allocation framework to actual broadband wireless channel development data. The allocation framework is derived from the optimal OFDM allocation scheme for a known channel: the channel development data is obtained from actual measurement of a broadband wireless mobile environment, Prediction techniques are employed to overcome the time lag between channel assessment and symbol transmission. We present the details of the predictive resource allocation scheme used and include a broad characterisation of the transmission environment in terms of the time-varying fading processes observed. We provide some results of the application of this scheme as typical performance levels that may be achieved in an actual transmission environment.