Broadband transmission using OFDM: system performance and receiver complexity

This paper investigates the system performance of coherent OFDM transmission over frequency selective fading channels taking into account the constraints imposed by the receiver complexity. The effects of synchronization errors in the receiver are analyzed. In a properly designed inner receiver, these errors lead to extra noise. Specifying the limits for this additional noise allows one to derive the requirements for each component and thus to design and optimize the inner receiver independently from the outer receiver. The resulting receiver structure and the synchronization algorithms applied are introduced. Particular attention is paid to the channel estimation unit since its accuracy is most essential for system performance. A short analysis of the complexity of the algorithms allows one to determine the limits of the single components. System simulations including inner and outer receiver are used to evaluate the ideal vs. the realizable performance of the receiver and thus show how it is bounded by receiver complexity.