Efficient channel description in time-frequency domain with application to flexible radio

The handling of dispersive channels poses one major challenge in the design of reconfigurable multi-standard radios, since very different techniques are established in this area for conventional single carrier, OFDM, and CDMA receivers. We discuss an approximate, efficient description of doubly dispersive discrete-time channels which is adaptable to different signal types and channel conditions. The proposed model maps the channel input onto the output via time-frequency signal representations. Optimized prototype functions for the encompassing Gabor transform and signal expansion are aimed at which minimize the model error for the case of WSSUS channels. We formulate an adequate objective function and employ numerical methods to obtain optimized prototypes on the basis of the long-term channel statistics. The paper concludes with the discussion of a possible flexible receiver architecture incorporating the channel model.