Performance Analysis of Dynamic OFDM-FDMA Systems with Inband Signaling

In this study we investigate the performance of dynamic OFDM-FDMA systems including the cost of signaling. As dynamic OFDM-FDMA systems assign system resources (= sub-carriers, modulation types, power) periodically to different terminals, changing these assignments for the down-link data transmission require the access point to inform terminals about their new resource assignments. Hence, in order to characterize the performance achieved by such a dynamic approach realistically, the signaling cost has to be included in the system model. We introduce two forms of representing the signaling information. In the first case, a fixed scheme is used which does not adapt to the signaling overhead by reducing the number of reassignments, for example. The second approach is more flexible in this sense and is able to reduce the signaling overhead significantly in some cases. However, it exploits the correlation in time of sub-carrier attenuations. We find that in general dynamic OFDM-FDMA systems still outperform static schemes significantly if the signaling overhead is taken into consideration. However, the performance difference between the dynamic and static schemes is now more sensible to the specific parameter set of the considered transmission scenario such as system bandwidth, sub-carrier number, length of the down-link frames etc. Especially as the system bandwidth increases, the gap between the potential performance achieved by dynamic schemes without considering the signaling cost and the realistic performance of such schemes becomes rather small, such that especially for future wireless communication systems a dynamic OFDM-FDMA approach is a recommended option in order to enhance the system performance.