A receiver in an OFDM based communication system is adapted to perform channel estimation using a received reference signal transmitted from at least one antenna The reference signal is substantially located into at least two OFDM symbols of a transmission time interval comprising of more than two OFDM symbols. A power level of said reference signal is divided into said non-consecutive OFDM symbols in said transmission time interval and adapted to use the reference signal located in a first OFDM symbol in succeeding transmission time intervals in addition to the reference symbols in a current transmission time interval and a preceding transmission time interval.