This paper investigates the possibility of using pre-equalizationon the up-link of a time division duplex (TDD) OFDM system. Theapplication of this principle is suggested to enhance the spectralefficiency by omitting the usage of training sequences on the up-link.This is desired in order to enable the efficient transmission of veryshort data packets, like single ATM cells. The principle proposed alsokeeps the complexity of synchronization low at the base station, whichis accessed by many users. We describe a simple scheme to limit thetransmission power on the up-link. The power is kept constant bydeleting subcarriers that are severely attenuated due to fading.Parameter estimation steps for retrieving the data at the base-stationare explained and evaluated. Those include the estimation of thetiming-offset, the carrier phase offset, and the received magnitude.Coherent demodulation is considered
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