Time synchronization in the uplink of an OFDM system

The use of orthogonal frequency division multiplex in a cellular system requires that the base station and the mobile station are time and frequency synchronized in order to preserve the orthogonality between the subcarriers. For the downlink a number of methods has been proposed for time and frequency synchronisation. For the uplink the problem is more difficult since each mobile has a unique radio transmission path to the base station. This article proposes and analyses the performance for a new scheme for initial time synchronisation. It is shown that a random access protocol based on the proposed scheme will have a good performance in a mobile radio environment.