It has been shown that cross-layer mechanisms (i.e. policies) potentially provide significant performance gains for various systems. This paper from Telecommunication Networks Group review several aspects of cross-layer system optimization regarding wireless OFDM (Orthogonal Frequency Division Multiplexing) systems. The paper discusses basic optimization models and present selected heuristic approaches realizing cross-layer policies by the means of dynamic resource allocation. Two specific areas are treated separately: Models and dynamic approaches for single transmitter/receiver pairs - i.e. a point-to-point communication scenario - as well as models and approaches for point-to-multi-point communication scenarios - such as the down-link of a wireless cell.