The present invention relates to a method, apparatus, system and computer program product, wherein a time division multiplex signal is received with a periodic first time period allocated to a downlink transmissions and a periodic second time period allocated to uplink transmissions. A decision time metric is obtained by correlating the received signal with a replica signal in order to detect a synchronization pattern provided in the first time period. Then, a slide window based normalization with a time window long enough to accommodate said second time period is applied to the decision time metric.