Carrier-recovery for multicarrier-transmission over mobile radio channels

The problems of digital transmission over mobile radio channels are investigated under the particular viewpoint of bandwidth efficiency and simple system design. It is shown that a multicarrier system with non-frequency selective and non-time-selective subchannels is a suitable design, which, however, requires an accurate carrier recovery. For this reason a decision feedback loop for tracking a carrier frequency offset is described, which applies to multicarrier systems with coherent or incoherent detection. By using the information of all subsystems at one time instant, the mentioned control loop is not sensitive to incorrect decisions and error propagation, even in the presence of fading channels. The performance of this control loop is investigated under certain mobile radio conditions; some simulation results show that an almost perfect carrier recovery is possible